← The Saudi aviation reference, in one place.
Aeronautical Information Manual (AIM)
Reproduced for study. Always verify against the official GACAR at gaca.gov.sa.
October 12, 2017
AdministrationU.S. Department
of Transportation
Federal Aviation
Aeronautical
Information
Manual Official Guide to
Basic Flight Information and ATC Procedures
An electronic version of this publication is on the internet at
http://www.faa.gov/atpubs
AIM
Record of Changes
Change Number Change Filed Comments
AIM 10/12/17
Explanation of Changes E of Chg−1Aeronautical Information Manual
Explanation of Changes
Effective: October 12, 2017
a. 1−1−9. Instrument Landing System (ILS)
5−4−20. Appr oach and Landing Minimums
This change updates guidance to improve clarity and
to be consistent with information contained in FAA
Order JO 7110. 65, Air Traffic Control, Paragraph
3−7−5, Precision Approach Critical Area.
b. 2−3−5. Holding Position Markings
This change, created in response to the Runway
Safety Council #34 Call to Action, emphasizes the
need for pilots to stop at holding position markings
and updates the language throughout the paragraph.
As such, several instances of “should” and “supposed
to” are replaced by the word “must” with regard to the
requirement for aircraft to stop at holding positionmarkings.
c. 3−5−7. Special Air Traffic Rules (SATR) and
Special Flight Rules Area (SFRA)
Appendix 3. Abbreviations
This change introduces SATR, makes reference to 14
CFR 93, and explains SFRAs. It provides information
needed to help pilots better understand their
responsibilities regarding SATR and SFRA.
d. 3−5−8. Weather Reconnaissance Area
(WRA)
Appendix 3. Abbreviations
This change introduces, defines, and explains WRAs
to better inform air traf fic control and pilots of WRAs
in general and weather reconnaissance/research
aircraft operations.
e. 4−1−21. Airport Reservation Operations and
Special Traffic Management Programs
This change updates guidance to be consistent with
FAA Order JO 7210.3, Paragraph 17 −13−4, Airport
Reservation Office. This change states that standby
lists are not maintained; and that flights with declared
emergencies do not require reservations. It also
updates contact information.f. 5−4−5. Instrument Appr oach Procedure
(IAP) Charts
This change clarifies the use of stepdown fixes on
approaches. This change also aligns our guidancewith that issued by the International Civil Aviation
Organization (ICAO).
g. 5−4−22. Use of Enhanced Flight Vision
Systems (EFVS) on Instrument Approaches
This change reflects the expansion of EFVS
operations explained in the December 2016 EFVS
Rule. It also adds figures that depict the two types of
EFVS operations.
h. 7−1
−4. Graphical Forecasts for Aviation
(GFA)
This change introduces new GFA products which
replace outdated textual area forecasts. These
products are expected to maximize operational
benefits to users and enhance the safety of theNational Airspace System.
i. 7−1−11. Weather Observing Programs
7−1−30. International Civil Aviation Orga-
nization (ICAO) Weather Formats
Appendix 3. Abbreviations
This change informs pilots of Automated Lightning
Detection and Reporting System (ALDARS) report-
ing capabilities so they are able to properly interpret
the weather observations, that include thunderstorms
(TS) and cloud −to−ground lightning, detected by
ALDARS. Specifically, the following codes should
be used: “TS” when cloud −to−ground lightning is
detected within 5 NM of the Airport Reference Point
(ARP), “VCTS” when cloud −to−ground lightning is
between 5 −10 NM of the ARP, and “LTG DSNT” in
Remarks when cloud −to−ground lightning is detect-
ed between 10 −30 NM of the ARP.
j. 7−1−13. ATC Inflight Weather Avoidance
Assistance
This change deletes the reference to composite
airspace, and specifically to North Pacific (NOPAC)
and Central East Pacific (CEPAC) routes. Weather
AIM 10/12/17
Explanation of Changes E of Chg−2deviations on those routes will be flown the same way
as all other operations in oceanic airspace. The AIM
will now be in congruence with the Aeronautical
Information Publication, ICAO Doc 4444, and the
Alaska and Pacific Chart Supplements.k. Entire publication.
Editorial/format changes were made where neces-
sary. Revision bars were not used when changes are
insignificant in nature.
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Comments/Corr 10/12/17
Basic Flight Info 10/12/17
Publication Policy 10/12/17
Reg & Advis Cir 10/12/17
Table of Contents
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Chapter 1. Air Navigation
Section 1. Navigation Aids
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Section 2. Performance −Based
Navigation (PBN) and Area
Navigation (RNA V)
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Chapter 2. Aeronautical
Lighting and Other Airport
Visual Aids
Section 1. Airport Lighting
Aids
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Section 2. Air Navigation and
Obstruction Lighting
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Section 3. Airport Marking
Aids and Signs
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Chapter 3. Airspace
Section 1. General
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Section 2. Controlled Airspace
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Section 3. Class G Airspace
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Section 4. Special Use
Airspace
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Section 5. Other Airspace
Areas
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Chapter 4. Air Traffic Control
Section 1. Services Available
to Pilots
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Section 2. Radio
Communications Phraseology
and Techniques
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Section 3. Airport Operations
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Section 4. ATC Clearances
and Aircraft Separation
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Section 5. Surveillance
Systems
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Section 6. Operational Policy/
Procedures for Reduced Vertical
Separation Minimum (RVSM) in
the Domestic U.S., Alaska,
Offshore Airspace and the
San Juan FIR
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Section 7. Operational Policy/
Procedures for the Gulf of Mexico
50 NM Lateral Separation
Initiative
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Chapter 5. Air Traffic
Procedures
Section 1. Preflight
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Section 2. Departure
Procedures
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Section 3. En Route
Procedures
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Section 4. Arrival Procedures
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Section 5. Pilot/Controller
Roles and Responsibilities
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Section 6. National Security
and Interception Procedures
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Chapter 6. Emergency
Procedures
Section 1. General
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Section 2. Emergency Services
Available to Pilots
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Section 3. Distress and
Urgency Procedures
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Section 4. Two −way Radio
Communications Failure
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Section 5. Aircraft Rescue
and Fire Fighting
Communications
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Chapter 7. Safety of Flight
Section 1. Meteorology
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Section 2. Altimeter Setting
Procedures
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Section 3. Wake Turbulence
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Section 4. Bird Hazards and
Flight Over National Refuges,
Parks, and Forests
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Section 5. Potential Flight
Hazards
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Section 6. Safety, Accident,
and Hazard Reports
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Chapter 8. Medical Facts
for Pilots
Section 1. Fitness for Flight
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8−1−8 10/12/17
8−1−9 10/12/17
Chapter 9. Aeronautical
Charts and Related
Publications
Section 1. Types of Charts
Available
9−1−1 10/12/17
9−1−2 10/12/17PAGE DATE
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9−1−9 10/12/17
9−1−10 10/12/17
9−1−11 10/12/17
9−1−12 10/12/17
9−1−13 10/12/17
Chapter 10. Helicopter
Operations
Section 1. Helicopter IFR
Operations
10−1−1 10/12/17
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10−1−7 10/12/17
Section 2. Special Operations
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Appendices
Appendix 1 −1 10/12/17
Env N/A
Appendix 2 −1 10/12/17
Appendix 3 −1 10/12/17
10/12/17 AIM
Checklist of Pages
Checklist of Pages CK−6PAGE DATE
Appendix 3 −2 10/12/17
Appendix 3 −3 10/12/17
Appendix 3 −4 10/12/17
Appendix 3 −5 10/12/17
Pilot/Controller Glossary
PCG−1 10/12/17
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Index
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Back Cover N/A
AIM
Subscription InformationSubscription Information
This and other selected Air Traffic publications are available online:
www.faa.gov/air_traffic/publications
To Obtain Copies of this Publication
General Public * Government Organizations*
Write:
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P.O. Box 979050St. Louis, MO 63197 −9000
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https://bookstore.gpo.govThis manual will be available on the FAA website by its effective date.
All Government organizations are responsible for viewing, download-
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Electronic subscription information can be obtained by visiting
http://www.faa.gov/air_traffic/publications.
*For those desiring printed copies, current pricing is available
on the GPO website at http://bookstore.gpo.gov.
AIM 10/12/17
Comments/CorrectionsComments/Corrections
The office of primary responsibility (OPR) for this manual is:
FAA Headquarters, Mission Support ServicesAir Traffic Procedures (AJV −8)
600 Independence Avenue, SW.
Washington, DC 20597
Proposed changes must be submitted electronically, using the following format, to the Air Traffic Procedures
Correspondence Mailbox at 9-AJV-8-HQ-Correspondence@faa.gov
Notice to Editor
The following comments/corrections are submitted concerning the information contained in:
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AIM 10/12/17
Comments/CorrectionsComments/Corrections
The office of primary responsibility (OPR) for this manual is:
FAA Headquarters, Mission Support ServicesAir Traffic Procedures (AJV −8)
600 Independence Avenue, SW.
Washington, DC 20597
Proposed changes must be submitted electronically, using the following format, to the Air Traffic Procedures
Correspondence Mailbox at 9-AJV-8-HQ-Correspondence@faa.gov
Notice to Editor
The following comments/corrections are submitted concerning the information contained in:
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AIM 10/12/17
Basic Flight Information and ATC ProceduresFederal Aviation Administration (FAA)
The Federal Aviation Administration is responsible
for ensuring the safe, efficient, and secure use of the
Nation’s airspace, by military as well as civil
aviation, for promoting safety in air commerce, for
encouraging and developing civil aeronautics,including new aviation technology, and for support-
ing the requirements of national defense.
The activities required to carry out these responsibili-
ties include: safety regulations; airspace managementand the establishment, operation, and maintenance of
a civil−military common system of air traffic control
(ATC) and navigation facilities; research and
development in support of the fostering of a national
system of airports, promulgation of standards andspecifications for civil airports, and administration of
Federal grants−in−aid for developing public airports;
various joint and cooperative activities with theDepartment of Defense; and technical assistance
(under State Department auspices) to other countries.
Aeronautical Information Manual (AIM)
Basic Flight Information and ATC Procedures
This manual is designed to provide the aviation
community with basic flight information and ATC
procedures for use in the National Airspace System
(NAS) of the United States. An international version
called the Aeronautical Information Publicationcontains parallel information, as well as specific
information on the international airports for use by
the international community.
This manual contains the fundamentals required in
order to fly in the United States NAS. It also contains
items of interest to pilots concerning health andmedical facts, factors affecting flight safety, a
pilot/controller glossary of terms used in the ATC
System, and information on safety, accident, andhazard reporting.
This manual is complemented by other operational
publications which are available via separatesubscriptions. These publications are:
Notices to Airmen publication - A publication
containing current Notices to Airmen (NOTAMs)which are considered essential to the safety of flight
as well as supplemental data affecting the otheroperational publications listed here. It also includes
current Flight Data Center NOTAMs, which are
regulatory in nature, issued to establish restrictions to
flight or to amend charts or published Instrument
Approach Procedures. This publication is issuedevery four weeks and is available through subscrip-
tion from the Superintendent of Documents.
The Chart Supplement U.S., the Chart
Supplement Alaska, and the Chart Supplement
Pacific − These publications contain information on
airports, communications, navigation aids, instru-
ment landing systems, VOR receiver check points,
preferred routes, Flight Service Station/Weather
Service telephone numbers, Air Route Traffic
Control Center (ARTCC) frequencies, part −time
surface areas, and various other pertinent special
notices essential to air navigation. These publications
are available through a network of FAA approvedprint providers. A listing of products, dates of latest
editions, and print providers is available on the
Aeronautical Information Services (AIS) website at:http://www.faa.gov/air_traffic/flight_info/aeronav/
print_providers/.
Publication Schedule
Basic or ChangeCutoff Date
for SubmissionEffective Date
of Publication
Basic Manual 4/27/17 10/12/17
Change 1 10/12/17 3/29/18
Change 2 3/29/18 9/13/18
Change 3 9/13/18 2/28/19
Basic Manual 2/28/19 8/15/19
AIM 10/12/17
Flight Information Publication PolicyFlight Information Publication Policy
The following is in essence, the statement issued by
the FAA Administrator and published in the
December 10, 1964, issue of the Federal Register,
concerning the FAA policy as pertaining to the type
of information that will be published as NOTAMsand in the Aeronautical Information Manual.
a. It is a pilot’s inherent responsibility to be alert
at all times for and in anticipation of all circum-
stances, situations, and conditions affecting the safe
operation of the aircraft. For example, a pilot should
expect to find air traffic at any time or place. At or
near both civil and military airports and in the vicin-
ity of known training areas, a pilot should expect
concentrated air traffic and realize concentrations
of air traffic are not limited to these places.
b. It is the general practice of the agency to adver-
tise by NOTAM or other flight information publica-
tions such information it may deem appropriate; in-
formation which the agency may from time to time
make available to pilots is solely for the purpose of
assisting them in executing their regulatory respon-
sibilities. Such information serves the aviation
community as a whole and not pilots individually.c. The fact that the agency under one particular
situation or another may or may not furnish in-
formation does not serve as a precedent of the
agency’s responsibility to the aviation community;
neither does it give assurance that other information
of the same or similar nature will be advertised, nor,
does it guarantee that any and all information
known to the agency will be advertised.
d. This publication, while not regulatory, pro-
vides informati on which reflects examples of oper-
ating techniques and procedures which may be re-
quirements in other federal publications or
regulations. It is made available solely to assist pi-lots in executing their responsibilities required by
other publications.
Consistent with the foregoing, it is the policy of the
Federal Aviation Administration to furnish in-formation only when, in the opinion of the agency,
a unique situation should be advertised and not to
furnish routine information such as concentrationsof air traffic, either civil or military. The
Aeronautical Information Manual will not contain
informative items concerning everyday circum-stances that pilots should, either by good practices
or regulation, expect to encounter or avoid.
AIM 10/12/17
Code of Federal Regulations and Advisory CircularsAeronautical Information Manual (AIM)
Code of Federal Regulations and Advisory Circulars
Code of Federal Regulations - The FAA publishes the
Code of Federal Regulations (CFR) to make readilyavailable to the aviation community the regulatory
requirements placed upon them. These regulations
are sold as individual parts by the Superintendent of
Documents.
The more frequently amended parts are sold on
subscription service with subscribers receiving
changes automatically as issued. Less active parts are
sold on a single −sale basis. Changes to single-sale
parts will be sold separately as issued. Information
concerning these changes will be furnished by theFAA through its Status of Federal Aviation
Regulations, AC 00 −44.
Advisory Circulars - The FAA issues Advisory
Circulars (AC) to inform the aviation public in a
systematic way of nonregulatory material. Unlessincorporated into a regulation by reference, the
contents of an advisory circular are not binding on the
public. Advisory Circulars are issued in a numbered
subject system corresponding to the subject areas of
the Code of Federal Regulations (CFR) (Title 14,Chapter 1, FAA).
AC 00−2, Advisory Circular Checklist and Status of
Other FAA Publications, contains advisory circulars
that are for sale as well as those distributed
free−of−charge by the FAA.NOTE−
The above information relating to CFRs and ACs isextracted from AC 00 −2. Many of the CFRs and ACs listed
in AC 00 −2 are cross −referenced in the AIM. These
regulatory and nonregulatory references cover a wide
range of subjects and are a source of detailed information
of value to the aviation community. AC 00 −2 is issued
annually and can be obtained free −of−charge from:
U.S. Department of Transportation
Subsequent Distribution OfficeArdmore East Business Center3341 Q 75th AvenueLandover, MD 20785
Telephone: 301 −322−4961
AC 00−2 may also be found at: http://www.faa.gov under
Advisory Circulars.
External References - All references to Advisory
Circulars and other FAA publications in the
Aeronautical Information Manual include the FAA
Advisory Circular or Order identification numbers(when available). However, due to varied publication
dates, the basic publication letter is not included.
EXAMPLE −
FAA Order JO 7110.65X, Air Traffic Contr ol, is r eferenced
as F AA Order JO 7110.65.
AIM 10/12/17
i Table of ContentsTable of Contents
Chapter 1. Air Navigation
Section 1. Navigation Aids
Paragraph Page
1-1-1. General 1-1-1 ............................................................
1-1-2. Nondirectional Radio Beacon (NDB) 1-1-1 ..................................
1-1-3. VHF Omni-directional Range (VOR) 1-1-1 .................................
1-1-4. VOR Receiver Check 1-1-3 ................................................
1-1-5. Tactical Air Navigation (TACAN) 1-1-4 ......................................
1-1-6. VHF Omni-directional Range/Tactical Air Navigation (VORTAC) 1-1-4 .........
1-1-7. Distance Measuring Equipment (DME) 1-1-5 ................................
1-1-8. Navigational Aid (NAVAID) Service Volumes 1-1-5 ...........................
1-1-9. Instrument Landing System (ILS) 1-1-8 ......................................
1-1-10. Simplified Directional Facility (SDF) 1-1-14 ..................................
1-1-11. NAVAID Identifier Removal During Maintenance 1-1-16 ......................
1-1-12. NAVAIDs with Voice 1-1-16 ...............................................
1-1-13. User Reports Requested on NAVAID or Global Navigation Satellite
System (GNSS) Performance or Interference 1-1-16 .........................
1-1-14. LORAN 1-1-17 ..........................................................
1-1-15. Inertial Reference Unit (IRU), Inertial Navigation System (INS), and
Attitude Heading Reference System (AHRS) 1-1-17 ........................
1-1-16. Doppler Radar 1-1-17 .....................................................
1-1-17. Global Positioning System (GPS) 1-1-17 .....................................
1-1-18. Wide Area Augmentation System (WAAS) 1-1-30 .............................
1-1-19. Ground Based Augmentation System (GBAS) Landing System (GLS) 1-1-35 ......
1-1-20. Precision Approach Systems other than ILS and GLS 1-1-35 ....................
Section 2. Performance-Based Navigation (PBN) and Area Navigation
(RNAV)
1-2-1. General 1-2-1 ............................................................
1-2-2. Required Navigation Performance (RNP) 1-2-4 ...............................
1-2-3. Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures
and Routes 1-2-6 .....................................................
1-2-4. Pilots and Air Traffic Controllers Recognizing Interference or Spoofing 1-2-8 ......
Chapter 2. Aeronautical Lighting and
Other Airport Visual Aids
Section 1. Airport Lighting Aids
2-1-1. Approach Light Systems (ALS) 2-1-1 ........................................
2-1-2. Visual Glideslope Indicators 2-1-1 ..........................................
2-1-3. Runway End Identifier Lights (REIL) 2-1-6 ..................................
2-1-4. Runway Edge Light Systems 2-1-6 ..........................................
2-1-5. In-runway Lighting 2-1-6 .................................................
2-1-6. Runway Status Light (RWSL) System 2-1-7 ...................................
2-1-7. StandAlone Final Approach Runway Occupancy Signal (FAROS) 2-1-10 ..........
2-1-8. Control of Lighting Systems 2-1-11 ...........................................
AIM 10/12/17
ii Table of ContentsParagraph Page
2-1-9. Pilot Control of Airport Lighting 2-1-11 ......................................
2-1-10. Airport/Heliport Beacons 2-1-14 ............................................
2-1-11. Taxiway Lights 2-1-15 .....................................................
Section 2. Air Navigation and Obstruction Lighting
2-2-1. Aeronautical Light Beacons 2-2-1 ...........................................
2-2-2. Code Beacons and Course Lights 2-2-1 ......................................
2-2-3. Obstruction Lights 2-2-1 ..................................................
Section 3. Airport Marking Aids and Signs
2-3-1. General 2-3-1 ............................................................
2-3-2. Airport Pavement Markings 2-3-1 ...........................................
2-3-3. Runway Markings 2-3-1 ...................................................
2-3-4. Taxiway Markings 2-3-7 ...................................................
2-3-5. Holding Position Markings 2-3-12 ............................................
2-3-6. Other Markings 2-3-16 .....................................................
2-3-7. Airport Signs 2-3-19 .......................................................
2-3-8. Mandatory Instruction Signs 2-3-20 ..........................................
2-3-9. Location Signs 2-3-23 ......................................................
2-3-10. Direction Signs 2-3-25 ....................................................
2-3-11. Destination Signs 2-3-28 ..................................................
2-3-12. Information Signs 2-3-29 ..................................................
2-3-13. Runway Distance Remaining Signs 2-3-29 ....................................
2-3-14. Aircraft Arresting Systems 2-3-30 ...........................................
2-3-15. Security Identifications Display Area (Airport Ramp Area) 2-3-31 ...............
Chapter 3. Airspace
Section 1. General
3-1-1. General 3-1-1 ............................................................
3-1-2. General Dimensions of Airspace Segments 3-1-1 ..............................
3-1-3. Hierarchy of Overlapping Airspace Designations 3-1-1 .........................
3-1-4. Basic VFR Weather Minimums 3-1-1 ........................................
3-1-5. VFR Cruising Altitudes and Flight Levels 3-1-2 ...............................
Section 2. Controlled Airspace
3-2-1. General 3-2-1 ............................................................
3-2-2. Class A Airspace 3-2-2 ....................................................
3-2-3. Class B Airspace 3-2-2 ....................................................
3-2-4. Class C Airspace 3-2-4 ....................................................
3-2-5. Class D Airspace 3-2-8 ....................................................
3-2-6. Class E Airspace 3-2-9 ....................................................
Section 3. Class G Airspace
3-3-1. General 3-3-1 ............................................................
3-3-2. VFR Requirements 3-3-1 ..................................................
3-3-3. IFR Requirements 3-3-1 ..................................................
AIM 10/12/17
iii Table of ContentsSection 4. Special Use Airspace
Paragraph Page
3-4-1. General 3-4-1 ............................................................
3-4-2. Prohibited Areas 3-4-1 ....................................................
3-4-3. Restricted Areas 3-4-1 ....................................................
3-4-4. Warning Areas 3-4-1 ......................................................
3-4-5. Military Operations Areas 3-4-2 ............................................
3-4-6. Alert Areas 3-4-2 .........................................................
3-4-7. Controlled Firing Areas 3-4-2 ..............................................
3-4-8. National Security Areas 3-4-2 ..............................................
Section 5. Other Airspace Areas
3-5-1. Airport Advisory/Information Services 3-5-1 ..................................
3-5-2. Military Training Routes 3-5-1 .............................................
3-5-3. Temporary Flight Restrictions 3-5-2 .........................................
3-5-4. Parachute Jump Aircraft Operations 3-5-5 ...................................
3-5-5. Published VFR Routes 3-5-5 ...............................................
3-5-6. Terminal Radar Service Area (TRSA) 3-5-9 ..................................
3-5-7. Special Air Traffic Rules (SATR) and Special Flight Rules Area (SFRA) 3-5-9 .....
3-5-8. Weather Reconnaissance Area (WRA) 3-5-9 .................................
Chapter 4. Air Traffic Control
Section 1. Services Available to Pilots
4-1-1. Air Route Traffic Control Centers 4-1-1 .....................................
4-1-2. Control T owers 4-1-1 .....................................................
4-1-3. Flight Service Stations 4-1-1 ...............................................
4-1-4. Recording and Monitoring 4-1-1 ............................................
4-1-5. Communications Release of IFR Aircraft Landing at an Airport Without an
Operating Control T ower 4-1-1 .........................................
4-1-6. Pilot Visits to Air Traffic Facilities 4-1-1 .....................................
4-1-7. Operation Rain Check 4-1-2 ...............................................
4-1-8. Approach Control Service for VFR Arriving Aircraft 4-1-2 .....................
4-1-9. Traffic Advisory Practices at Airports Without Operating Control T owers 4-1-2 ....
4-1-10. IFR Approaches/Ground Vehicle Operations 4-1-6 ...........................
4-1-11. Designated UNICOM/MULTICOM Frequencies 4-1-6 .......................
4-1-12. Use of UNICOM for ATC Purposes 4-1-7 ...................................
4-1-13. Automatic T erminal Information Service (ATIS) 4-1-7 ........................
4-1-14. Automatic Flight Information Service (AFIS) - Alaska FSSs Only 4-1-8 .........
4-1-15. Radar Traffic Information Service 4-1-9 ....................................
4-1-16. Safety Alert 4-1-10 .......................................................
4-1-17. Radar Assistance to VFR Aircraft 4-1-11 ....................................
4-1-18. Terminal Radar Services for VFR Aircraft 4-1-12 .............................
4-1-19. Tower En Route Control (TEC) 4-1-14 ......................................
4-1-20. Transponder Operation 4-1-15 .............................................
4-1-21. Airport Reservation Operations and Special Traffic Management Programs 4-1-18 .
4-1-22. Requests for Waivers and Authorizations from Title 14, Code of Federal
Regulations (14 CFR) 4-1-20 ............................................
4-1-23. Weather System Processor 4-1-20 ...........................................
AIM 10/12/17
iv Table of ContentsSection 2. Radio Communications Phraseology
and Techniques
Paragraph Page
4-2-1. General 4-2-1 ............................................................
4-2-2. Radio T echnique 4-2-1 ....................................................
4-2-3. Contact Procedures 4-2-1 ..................................................
4-2-4. Aircraft Call Signs 4-2-3 ...................................................
4-2-5. Description of Interchange or Leased Aircraft 4-2-4 ...........................
4-2-6. Ground Station Call Signs 4-2-4 ............................................
4-2-7. Phonetic Alphabet 4-2-5 ...................................................
4-2-8. Figures 4-2-6 ............................................................
4-2-9. Altitudes and Flight Levels 4-2-6 ...........................................
4-2-10. Directions 4-2-6 .........................................................
4-2-11. Speeds 4-2-6 ............................................................
4-2-12. Time 4-2-6 .............................................................
4-2-13. Communications with T ower when Aircraft Transmitter or Receiver or Both
are Inoperative 4-2-7 ..................................................
4-2-14. Communications for VFR Flights 4-2-8 .....................................
Section 3. Airport Operations
4-3-1. General 4-3-1 ............................................................
4-3-2. Airports with an Operating Control T ower 4-3-1 ..............................
4-3-3. Traffic Patterns 4-3-2 .....................................................
4-3-4. Visual Indicators at Airports Without an Operating Control T ower 4-3-6 ..........
4-3-5. Unexpected Maneuvers in the Airport Traffic Pattern 4-3-6 .....................
4-3-6. Use of Runways/Declared Distances 4-3-7 ....................................
4-3-7. Low Level Wind Shear/Microburst Detection Systems 4-3-12 ....................
4-3-8. Braking Action Reports and Advisories 4-3-12 .................................
4-3-9. Runway Condition Reports 4-3-13 ...........................................
4-3-10. Intersection T akeoffs 4-3-15 ...............................................
4-3-11. Pilot Responsibilities When Conducting Land and Hold Short
Operations (LAHSO) 4-3-15 ............................................
4-3-12. Low Approach 4-3-18 .....................................................
4-3-13. Traffic Control Light Signals 4-3-18 .........................................
4-3-14. Communications 4-3-19 ...................................................
4-3-15. Gate Holding Due to Departure Delays 4-3-20 ...............................
4-3-16. VFR Flights in T erminal Areas 4-3-20 .......................................
4-3-17. VFR Helicopter Operations at Controlled Airports 4-3-20 ......................
4-3-18. Taxiing 4-3-22 ...........................................................
4-3-19. Taxi During Low Visibility 4-3-23 ...........................................
4-3-20. Exiting the Runway After Landing 4-3-24 ....................................
4-3-21. Practice Instrument Approaches 4-3-24 ......................................
4-3-22. Option Approach 4-3-25 ..................................................
4-3-23. Use of Aircraft Lights 4-3-26 ...............................................
4-3-24. Flight Inspection/`Flight Check' Aircraft in T erminal Areas 4-3-26 ...............
4-3-25. Hand Signals 4-3-27 ......................................................
4-3-26. Operations at Uncontrolled Airports With Automated Surface Observing
System (ASOS)/Automated Weather Sensor System(AWSS)/Automated
Weather Observing System (AWOS) 4-3-31 ................................
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v Table of ContentsSection 4. ATC Clearances and Aircraft Separation
Paragraph Page
4-4-1. Clearance 4-4-1 ..........................................................
4-4-2. Clearance Prefix 4-4-1 ....................................................
4-4-3. Clearance Items 4-4-1 .....................................................
4-4-4. Amended Clearances 4-4-2 ................................................
4-4-5. Coded Departure Route (CDR) 4-4-3 .......................................
4-4-6. Special VFR Clearances 4-4-3 ..............................................
4-4-7. Pilot Responsibility upon Clearance Issuance 4-4-4 ............................
4-4-8. IFR Clearance VFR-on-top 4-4-4 .........................................
4-4-9. VFR/IFR Flights 4-4-5 ....................................................
4-4-10. Adherence to Clearance 4-4-5 .............................................
4-4-11. IFR Separation Standards 4-4-7 ...........................................
4-4-12. Speed Adjustments 4-4-7 .................................................
4-4-13. Runway Separation 4-4-10 .................................................
4-4-14. Visual Separation 4-4-10 ..................................................
4-4-15. Use of Visual Clearing Procedures 4-4-11 ....................................
4-4-16. Traffic Alert and Collision Avoidance System (TCAS I & II) 4-4-11 ..............
4-4-17. Traffic Information Service (TIS) 4-4-12 .....................................
Section 5. Surveillance Systems
4-5-1. Radar 4-5-1 .............................................................
4-5-2. Air Traffic Control Radar Beacon System (ATCRBS) 4-5-2 .....................
4-5-3. Surveillance Radar 4-5-7 ..................................................
4-5-4. Precision Approach Radar (PAR) 4-5-7 ......................................
4-5-5. Airport Surface Detection Equipment (ASDE-X)/Airport Surface Surveillance
Capability (ASSC) 4-5-7 ...............................................
4-5-6. Traffic Information Service (TIS) 4-5-8 ......................................
4-5-7. Automatic Dependent Surveillance-Broadcast (ADS-B) Services 4-5-14 .........
4-5-8. Traffic Information Service- Broadcast (TIS-B) 4-5-18 ........................
4-5-9. Flight Information Service- Broadcast (FIS-B) 4-5-19 .........................
4-5-10. Automatic Dependent Surveillance-Rebroadcast (ADS-R) 4-5-21 ..............
Section 6. Operational Policy/Procedures for Reduced Vertical
Separation Minimum (RVSM) in the Domestic U.S., Alaska, Offshore
Airspace and the San Juan FIR
4-6-1. Applicability and RVSM Mandate (Date/Time and Area) 4-6-1 .................
4-6-2. Flight Level Orientation Scheme 4-6-1 ......................................
4-6-3. Aircraft and Operator Approval Policy/Procedures, RVSM Monitoring and
Databases for Aircraft and Operator Approval 4-6-2 .......................
4-6-4. Flight Planning into RVSM Airspace 4-6-2 ...................................
4-6-5. Pilot RVSM Operating Practices and Procedures 4-6-3 .........................
4-6-6. Guidance on Severe Turbulence and Mountain Wave Activity (MWA) 4-6-3 .......
4-6-7. Guidance on Wake Turbulence 4-6-5 ........................................
4-6-8. Pilot/Controller Phraseology 4-6-5 ..........................................
4-6-9. Contingency Actions: Weather Encounters and Aircraft System Failures that
Occur After Entry into RVSM Airspace 4-6-7 .............................
4-6-10. Procedures for Accommodation of Non-RVSM Aircraft 4-6-9 .................
4-6-11. Non-RVSM Aircraft Requesting Climb to and Descent from Flight Levels
Above RVSM Airspace Without Intermediate Level Off 4-6-10 ...............
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vi Table of ContentsSection 7. Operational Policy/Procedures for the Gulf of Mexico 50 NM
Lateral Separation Initiative
Paragraph Page
4-7-1. Introduction and Background 4-7-1 .........................................
4-7-2. Lateral Separation Minima Applied 4-7-1 ....................................
4-7-3. Operation on Routes on the Periphery of the Gulf of Mexico CTAs 4-7-1 .........
4-7-4. Provisions for Non-RNP 10 Aircraft (Not Authorized RNP 10 or RNP 4) 4-7-1 ...
4-7-5. Operator Action 4-7-2 ....................................................
4-7-6. RNP 10 or RNP 4 Authorization: Policy and Procedures for Aircraft and
Operators 4-7-2 ......................................................
4-7-7. Flight Planning Requirements 4-7-3 .........................................
4-7-8. Pilot and Dispatcher Procedures: Basic and Inflight Contingency Procedures 4-7-3 .
Chapter 5. Air Traffic Procedures
Section 1. Preflight
5-1-1. Preflight Preparation 5-1-1 ................................................
5-1-2. Follow IFR Procedures Even When Operating VFR 5-1-2 ......................
5-1-3. Notice to Airmen (NOTAM) System 5-1-2 ...................................
5-1-4. Flight Plan - VFR Flights 5-1-7 ............................................
5-1-5. Operational Information System (OIS) 5-1-10 .................................
5-1-6. Flight Plan- Defense VFR (DVFR) Flights 5-1-10 .............................
5-1-7. Composite Flight Plan (VFR/IFR Flights) 5-1-11 ...............................
5-1-8. Flight Plan (FAA Form 7233-1)- Domestic IFR Flights 5-1-11 ..................
5-1-9. International Flight Plan (FAA Form 7233-4)- IFR Flights (For Domestic or
International Flights) 5-1-17 .............................................
5-1-10. IFR Operations to High Altitude Destinations 5-1-27 ..........................
5-1-11. Flights Outside the U.S. and U.S. T erritories 5-1-28 ...........................
5-1-12. Change in Flight Plan 5-1-30 ...............................................
5-1-13. Change in Proposed Departure Time 5-1-30 ..................................
5-1-14. Closing VFR/DVFR Flight Plans 5-1-30 .....................................
5-1-15. Canceling IFR Flight Plan 5-1-30 ...........................................
5-1-16. RNAV and RNP Operations 5-1-31 .........................................
5-1-17. Cold T emperature Operations 5-1-31 ........................................
Section 2. Departure Procedures
5-2-1. Pre‐taxi Clearance Procedures 5-2-1 .........................................
5-2-2. Automated Pre-Departure Clearance Procedures 5-2-1 ........................
5-2-3. Taxi Clearance 5-2-2 ......................................................
5-2-4. Line Up and Wait (LUAW) 5-2-2 ...........................................
5-2-5. Abbreviated IFR Departure Clearance (Cleared. . .as Filed) Procedures 5-2-3 .....
5-2-6. Departure Restrictions, Clearance Void Times, Hold for Release, and Release
Times 5-2-4 ..........................................................
5-2-7. Departure Control 5-2-5 ..................................................
5-2-8. Instrument Departure Procedures (DP) - Obstacle Departure Procedures
(ODP) and Standard Instrument Departures (SID) 5-2-6 ...................
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vii Table of ContentsSection 3. En Route Procedures
Paragraph Page
5-3-1. ARTCC Communications 5-3-1 ............................................
5-3-2. Position Reporting 5-3-3 ..................................................
5-3-3. Additional Reports 5-3-4 ..................................................
5-3-4. Airways and Route Systems 5-3-5 ...........................................
5-3-5. Airway or Route Course Changes 5-3-7 ......................................
5-3-6. Changeover Points (COPs) 5-3-8 ...........................................
5-3-7. Minimum Turning Altitude (MTA) 5-3-8 .....................................
5-3-8. Holding 5-3-8 ............................................................
Section 4. Arrival Procedures
5-4-1. Standard T erminal Arrival (STAR) Procedures 5-4-1 ...........................
5-4-2. Local Flow Traffic Management Program 5-4-3 ...............................
5-4-3. Approach Control 5-4-3 ...................................................
5-4-4. Advance Information on Instrument Approach 5-4-4 ..........................
5-4-5. Instrument Approach Procedure (IAP) Charts 5-4-5 ...........................
5-4-6. Approach Clearance 5-4-25 .................................................
5-4-7. Instrument Approach Procedures 5-4-27 ......................................
5-4-8. Special Instrument Approach Procedures 5-4-28 ...............................
5-4-9. Procedure Turn and Hold-in-lieu of Procedure Turn 5-4-29 ....................
5-4-10. Timed Approaches from a Holding Fix 5-4-32 ................................
5-4-11. Radar Approaches 5-4-35 .................................................
5-4-12. Radar Monitoring of Instrument Approaches 5-4-36 ...........................
5-4-13. ILS Approaches to Parallel Runways 5-4-36 ..................................
5-4-14. Parallel ILS Approaches (Dependent) (See FIG 5-4-21.) 5-4-39 ...............
5-4-15. Simultaneous (Parallel) Independent ILS/RNAV/GLS Approaches
(See FIG 5-4-22.) 5-4-41 ..............................................
5-4-16. Simultaneous Close Parallel ILS PRM/RNAV PRM/GLS PRM Approaches
and Simultaneous Offset Instrument Approaches (SOIA)
(See FIG 5-4-23.) 5-4-43 ..............................................
5-4-17. Simultaneous Converging Instrument Approaches 5-4-50 .......................
5-4-18. RNP AR Instrument Approach Procedures 5-4-51 .............................
5-4-19. Side-step Maneuver 5-4-53 ...............................................
5-4-20. Approach and Landing Minimums 5-4-53 ....................................
5-4-21. Missed Approach 5-4-56 ..................................................
5-4-22. Use of Enhanced Flight Vision Systems (EFVS) on Instrument Approaches 5-4-58 .
5-4-23. Visual Approach 5-4-62 ...................................................
5-4-24. Charted Visual Flight Procedure (CVFP) 5-4-63 ..............................
5-4-25. Contact Approach 5-4-63 ..................................................
5-4-26. Landing Priority 5-4-64 ...................................................
5-4-27. Overhead Approach Maneuver 5-4-64 .......................................
Section 5. Pilot/Controller Roles and Responsibilities
5-5-1. General 5-5-1 ............................................................
5-5-2. Air Traffic Clearance 5-5-1 ................................................
5-5-3. Contact Approach 5-5-2 ...................................................
5-5-4. Instrument Approach 5-5-2 ................................................
5-5-5. Missed Approach 5-5-3 ...................................................
5-5-6. Radar Vectors 5-5-3 ......................................................
5-5-7. Safety Alert 5-5-3 ........................................................
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viii Table of ContentsParagraph Page
5-5-8. See and Avoid 5-5-4 ......................................................
5-5-9. Speed Adjustments 5-5-4 ..................................................
5-5-10. Traffic Advisories (Traffic Information) 5-5-5 ................................
5-5-11. Visual Approach 5-5-5 ...................................................
5-5-12. Visual Separation 5-5-6 ..................................................
5-5-13. VFR‐on‐top 5-5-6 .......................................................
5-5-14. Instrument Departures 5-5-7 ..............................................
5-5-15. Minimum Fuel Advisory 5-5-7 .............................................
5-5-16. RNAV and RNP Operations 5-5-7 .........................................
Section 6. National Security and Interception Procedures
5-6-1. National Security 5-6-1 ....................................................
5-6-2. National Security Requirements 5-6-1 .......................................
5-6-3. Definitions 5-6-1 .........................................................
5-6-4. ADIZ Requirements 5-6-2 .................................................
5-6-5. Civil Aircraft Operations T o or From U.S. T erritorial Airspace 5-6-3 .............
5-6-6. Civil Aircraft Operations Within U.S. T erritorial Airspace 5-6-4 .................
5-6-7. Civil Aircraft Operations Transiting U.S. T erritorial Airspace 5-6-5 ..............
5-6-8. Foreign State Aircraft Operations 5-6-6 .....................................
5-6-9. FAA/TSA Airspace Waivers 5-6-7 ...........................................
5-6-10. TSA Aviation Security Programs 5-6-7 ......................................
5-6-11. FAA Flight Routing Authorizations 5-6-7 ...................................
5-6-12. Emergency Security Control of Air Traffic (ESCAT) 5-6-7 .....................
5-6-13. Interception Procedures 5-6-8 .............................................
5-6-14. Law Enforcement Operations by Civil and Military Organizations 5-6-10 .........
5-6-15. Interception Signals 5-6-11 ................................................
5-6-16. ADIZ Boundaries and Designated Mountainous Areas (See FIG 5-6-3.) 5-6-13 ..
5-6-17. Visual Warning System (VWS) 5-6-14 .......................................
Chapter 6. Emergency Procedures
Section 1. Genera
6-1-1. Pilot Responsibility and Authority 6-1-1 .....................................
6-1-2. Emergency Condition- Request Assistance Immediately 6-1-1 ..................
Section 2. Emergency Services Available to Pilots
6-2-1. Radar Service for VFR Aircraft in Difficulty 6-2-1 ............................
6-2-2. Transponder Emergency Operation 6-2-1 ....................................
6-2-3. Intercept and Escort 6-2-1 .................................................
6-2-4. Emergency Locator Transmitter (ELT) 6-2-2 .................................
6-2-5. FAA K-9 Explosives Detection T eam Program 6-2-3 ..........................
6-2-6. Search and Rescue 6-2-4 ..................................................
Section 3. Distress and Urgency Procedures
6-3-1. Distress and Urgency Communications 6-3-1 .................................
6-3-2. Obtaining Emergency Assistance 6-3-1 ......................................
6-3-3. Ditching Procedures 6-3-3 .................................................
6-3-4. Special Emergency (Air Piracy) 6-3-6 ........................................
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ix Table of ContentsParagraph Page
6-3-5. Fuel Dumping 6-3-7 ......................................................
Section 4. Two‐way Radio Communications Failure
6-4-1. Two‐way Radio Communications Failure 6-4-1 ................................
6-4-2. Transponder Operation During Two‐way Communications Failure 6-4-2 ..........
6-4-3. Reestablishing Radio Contact 6-4-2 .........................................
Section 5. Aircraft Rescue and Fire Fighting Communications
6-5-1. Discrete Emergency Frequency 6-5-1 ........................................
6-5-2. Radio Call Signs 6-5-1 ....................................................
6-5-3. ARFF Emergency Hand Signals 6-5-1 .......................................
Chapter 7. Safety of Flight
Section 1. Meteorology
7-1-1. National Weather Service Aviation Weather Service Program 7-1-1 ..............
7-1-2. FAA Weather Services 7-1-2 ...............................................
7-1-3. Use of Aviation Weather Products 7-1-2 .....................................
7-1-4. Graphical Forecasts for Aviation (GFA) 7-1-5 ................................
7-1-5. Preflight Briefing 7-1-7 ....................................................
7-1-6. Inflight Aviation Weather Advisories 7-1-9 ...................................
7-1-7. Categorical Outlooks 7-1-16 ................................................
7-1-8. Telephone Information Briefing Service (TIBS) 7-1-17 ..........................
7-1-9. Transcribed Weather Broadcast (TWEB) (Alaska Only) 7-1-17 ...................
7-1-10. Inflight Weather Broadcasts 7-1-17 .........................................
7-1-11. Flight Information Services (FIS) 7-1-20 .....................................
7-1-12. Weather Observing Programs 7-1-24 ........................................
7-1-13. Weather Radar Services 7-1-32 .............................................
7-1-14. ATC Inflight Weather Avoidance Assistance 7-1-36 ............................
7-1-15. Runway Visual Range (RVR) 7-1-38 ........................................
7-1-16. Reporting of Cloud Heights 7-1-40 ..........................................
7-1-17. Reporting Prevailing Visibility 7-1-40 ........................................
7-1-18. Estimating Intensity of Rain and Ice Pellets 7-1-40 ............................
7-1-19. Estimating Intensity of Snow or Drizzle (Based on Visibility) 7-1-41 ..............
7-1-20. Pilot Weather Reports (PIREPs) 7-1-41 ......................................
7-1-21. PIREPs Relating to Airframe Icing 7-1-42 ....................................
7-1-22. Definitions of Inflight Icing T erms 7-1-43 ....................................
7-1-23. PIREPs Relating to Turbulence 7-1-45 .......................................
7-1-24. Wind Shear PIREPs 7-1-46 ................................................
7-1-25. Clear Air Turbulence (CAT) PIREPs 7-1-46 ..................................
7-1-26. Microbursts 7-1-46 .......................................................
7-1-27. PIREPs Relating to Volcanic Ash Activity 7-1-57 ..............................
7-1-28. Thunderstorms 7-1-57 ....................................................
7-1-29. Thunderstorm Flying 7-1-58 ...............................................
7-1-30. Key to Aerodrome Forecast (TAF) and Aviation Routine Weather
Report (METAR) 7-1-60 ................................................
7-1-31. International Civil Aviation Organization (ICAO) Weather Formats 7-1-62 .......
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x Table of ContentsSection 2. Altimeter Setting Procedures
Paragraph Page
7-2-1. General 7-2-1 ............................................................
7-2-2. Procedures 7-2-1 .........................................................
7-2-3. Altimeter Errors 7-2-3 ....................................................
7-2-4. High Barometric Pressure 7-2-4 ............................................
7-2-5. Low Barometric Pressure 7-2-4 .............................................
Section 3. Wake Turbulence
7-3-1. General 7-3-1 ............................................................
7-3-2. Vortex Generation 7-3-1 ..................................................
7-3-3. Vortex Strength 7-3-1 .....................................................
7-3-4. Vortex Behavior 7-3-2 .....................................................
7-3-5. Operations Problem Areas 7-3-5 ............................................
7-3-6. Vortex Avoidance Procedures 7-3-5 .........................................
7-3-7. Helicopters 7-3-6 .........................................................
7-3-8. Pilot Responsibility 7-3-6 ..................................................
7-3-9. Air Traffic Wake Turbulence Separations 7-3-7 ................................
Section 4. Bird Hazards and Flight Over National Refuges, Parks, and
Forests
7-4-1. Migratory Bird Activity 7-4-1 ..............................................
7-4-2. Reducing Bird Strike Risks 7-4-1 ...........................................
7-4-3. Reporting Bird Strikes 7-4-1 ...............................................
7-4-4. Reporting Bird and Other Wildlife Activities 7-4-1 ............................
7-4-5. Pilot Advisories on Bird and Other Wildlife Hazards 7-4-2 ......................
7-4-6. Flights Over Charted U.S. Wildlife Refuges, Parks, and Forest Service Areas 7-4-2 .
Section 5. Potential Flight Hazards
7-5-1. Accident Cause Factors 7-5-1 ..............................................
7-5-2. VFR in Congested Areas 7-5-1 .............................................
7-5-3. Obstructions T o Flight 7-5-1 ...............................................
7-5-4. Avoid Flight Beneath Unmanned Balloons 7-5-2 ..............................
7-5-5. Unmanned Aircraft Systems 7-5-2 ..........................................
7-5-6. Mountain Flying 7-5-3 ....................................................
7-5-7. Use of Runway Half-way Signs at Unimproved Airports 7-5-5 ..................
7-5-8. Seaplane Safety 7-5-6 .....................................................
7-5-9. Flight Operations in Volcanic Ash 7-5-7 .....................................
7-5-10. Emergency Airborne Inspection of Other Aircraft 7-5-8 .......................
7-5-11. Precipitation Static 7-5-9 .................................................
7-5-12. Light Amplification by Stimulated Emission of Radiation (Laser) Operations
and Reporting Illumination of Aircraft 7-5-10 ..............................
7-5-13. Flying in Flat Light and White Out Conditions 7-5-11 ..........................
7-5-14. Operations in Ground Icing Conditions 7-5-12 ................................
7-5-15. Avoid Flight in the Vicinity of Exhaust Plumes (Smoke Stacks and
Cooling T owers) 7-5-13 .................................................
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xi Table of ContentsSection 6. Safety, Accident, and Hazard Reports
Paragraph Page
7-6-1. Aviation Safety Reporting Program 7-6-1 ....................................
7-6-2. Aircraft Accident and Incident Reporting 7-6-1 ...............................
7-6-3. Near Midair Collision Reporting 7-6-2 ......................................
7-6-4. Unidentified Flying Object (UFO) Reports 7-6-3 ..............................
7-6-5. Safety Alerts For Operators (SAFO) and Information For Operators (InFO) 7-6-3 .
Chapter 8. Medical Facts for Pilots
Section 1. Fitness for Flight
8-1-1. Fitness For Flight 8-1-1 ...................................................
8-1-2. Effects of Altitude 8-1-3 ...................................................
8-1-3. Hyperventilation in Flight 8-1-5 ............................................
8-1-4. Carbon Monoxide Poisoning in Flight 8-1-5 ..................................
8-1-5. Illusions in Flight 8-1-5 ....................................................
8-1-6. Vision in Flight 8-1-6 .....................................................
8-1-7. Aerobatic Flight 8-1-8 .....................................................
8-1-8. Judgment Aspects of Collision Avoidance 8-1-8 ...............................
Chapter 9. Aeronautical Charts and
Related Publications
Section 1. Types of Charts Available
9-1-1. General 9-1-1 ............................................................
9-1-2. Obtaining Aeronautical Charts 9-1-1 ........................................
9-1-3. Selected Charts and Products Available 9-1-1 .................................
9-1-4. General Description of Each Chart Series 9-1-1 ...............................
9-1-5. Where and How to Get Charts of Foreign Areas 9-1-13 .........................
Chapter 10. Helicopter Operations
Section 1. Helicopter IFR Operations
10-1-1. Helicopter Flight Control Systems 10-1-1 ....................................
10-1-2. Helicopter Instrument Approaches 10-1-3 ....................................
10-1-3. Helicopter Approach Procedures to VFR Heliports 10-1-5 ......................
10-1-4. The Gulf of Mexico Grid System 10-1-6 .....................................
Section 2. Special Operations
10-2-1. Offshore Helicopter Operations 10-2-1 ......................................
10-2-2. Helicopter Night VFR Operations 10-2-7 ....................................
10-2-3. Landing Zone Safety 10-2-10 ...............................................
10-2-4. Emergency Medical Service (EMS) Multiple Helicopter Operations 10-2-16 ........
AIM 10/12/17
xii Table of ContentsAppendices
Paragraph Page
Appendix 1. Bird/Other Wildlife Strike Report Appendix 1-1 ..................................
Appendix 2. Volcanic Activity Reporting Form (VAR) Appendix 2-1 ............................
Appendix 3. Abbreviations/Acronyms Appendix 3-1 ..........................................
PILOT/CONTROLLER GLOSSARY PCG-1 ..........................................
INDEX I-1 ....................................................................
AIM 10/12/17
1−1−1 Navigation AidsChapter 1. Air Navigation
Section 1. Navigation Aids
1−1−1. General
a.Various types of air navigation aids are in use
today, each serving a special purpose. These aids have
varied owners and operators, namely: the Federal
Aviation Administration (FAA), the military ser-
vices, private organizations, individual states andforeign governments. The FAA has the statutory
authority to establish, operate, maintain air naviga-
tion facilities and to prescribe standards for theoperation of any of these aids which are used for
instrument flight in federally controlled airspace.
These aids are tabulated in the Chart Supplement U.S.
b.Pilots should be aware of the possibility of
momentary erroneous indications on cockpit displays
when the primary signal generator for a ground −
based navigational transmitter (for example, a
glideslope, VOR, or nondirectional beacon) is
inoperative. Pilots should disregard any navigationindication, regardless of its apparent validity, if the
particular transmitter was identified by NOTAM or
otherwise as unusable or inoperative.
1−1−2. Nondirectional Radio Beacon (NDB)
a.A low or medium frequency radio beacon
transmits nondirectional signals whereby the pilot of
an aircraft properly equipped can determine bearings
and “home” on the station. These facilities normallyoperate in a frequency band of 190 to 535 kilohertz
(kHz), according to ICAO Annex 10 the frequency
range for NDBs is between 190 and 1750 kHz, andtransmit a continuous carrier with either 400 or
1020 hertz (Hz) modulation. All radio beacons
except the compass locators transmit a continuousthree−letter identification in code except during voice
transmissions.
b.When a radio beacon is used in conjunction with
the Instrument Landing System markers, it is called
a Compass Locator.
c.V oice transmissions are made on radio beacons
unless the letter “W” (without voice) is included in
the class designator (HW).d.Radio beacons are subject to disturbances that
may result in erroneous bearing information. Such
disturbances result from such factors as lightning,
precipitation static, etc. At night, radio beacons are
vulnerable to interference from distant stations.Nearly all disturbances which affect the Automatic
Direction Finder (ADF) bearing also affect the
facility’s identification. Noisy identification usuallyoccurs when the ADF needle is erratic. V oice, music
or erroneous identification may be heard when a
steady false bearing is being displayed. Since ADFreceivers do not have a “flag” to warn the pilot when
erroneous bearing information is being displayed, the
pilot should continuously monitor the NDB’sidentification.
1−1−3. VHF Omni −directional Range (VOR)
a.VORs operate within the 108.0 to 117.95 MHz
frequency band and have a power output necessary to
provide coverage within their assigned operational
service volume. They are subject to line −of−sight
restrictions, and the range varies proportionally to the
altitude of the receiving equipment.
NOTE−
Normal service ranges for the various classes of VORs are
given in Navigational Aid (NAVAID) Service Volumes,Paragraph 1 −1−8.
b.Most VORs are equipped for voice transmis-
sion on the VOR frequency. VORs without voicecapability are indicated by the letter “W” (without
voice) included in the class designator (VORW).
c.The only positive method of identifying a VOR
is by its Morse Code identification or by the recordedautomatic voice identification which is always
indicated by use of the word “VOR” following the
range’s name. Reliance on determining the identifica-
tion of an omnirange should never be placed on
listening to voice transmissions by the Flight Service
Station (FSS) (or approach control facility) involved.
Many FSSs remotely operate several omniranges
with different names. In some cases, none of the
VORs have the name of the “parent” FSS. Duringperiods of maintenance, the facility may radiate a
T−E−S−T code ( -/C0068 /C0068/C0068/C0068 -) or the code may be
AIM 10/12/17
1−1−2 Navigation Aidsremoved. Some VOR equipment decodes the
identifier and displays it to the pilot for verification
to charts, while other equipment simply displays the
expected identifier from a database to aid in
verification to the audio tones. Y ou should be familiar
with your equipment and use it appropriately. If your
equipment automatically decodes the identifier, it is
not necessary to listen to the audio identification.
d.V oice identification has been added to numer-
ous VORs. The transmission consists of a voiceannouncement, “AIRVILLE VOR” alternating with
the usual Morse Code identification.
e.The effectiveness of the VOR depends upon
proper use and adjustment of both ground and
airborne equipment.
1. Accuracy. The accuracy of course align-
ment of the VOR is excellent, being generally plus or
minus 1 degree.
2. Roughness. On some VORs, minor course
roughness may be observed, evidenced by course
needle or brief flag alarm activity (some receivers are
more susceptible to these irregularities than others).
At a few stations, usually in mountainous terrain, the
pilot may occasionally observe a brief course needleoscillation, similar to the indication of “approaching
station.” Pilots flying over unfamiliar routes are
cautioned to be on the alert for these vagaries, and in
particular, to use the “to/from” indicator to determine
positive station passage.
(a)Certain propeller revolutions per minute
(RPM) settings or helicopter rotor speeds can causethe VOR Course Deviation Indicator to fluctuate as
much as plus or minus six degrees. Slight changes to
the RPM setting will normally smooth out thisroughness. Pilots are urged to check for this
modulation phenomenon prior to reporting a VOR
station or aircraft equipment for unsatisfactoryoperation.
f. The VOR Minimum Operational Network
(MON). As flight procedures and route structure
based on VORs are gradually being replaced with
Performance −Based Navigation (PBN) procedures,
the FAA is removing selected VORs from service.
PBN procedures are primarily enabled by GPS and its
augmentation systems, collectively referred to asGlobal Navigation Satellite System (GNSS). Aircraft
that carry DME/DME equipment can also use RNA V
which provides a backup to continue flying PBNduring a GNSS disruption. For those aircraft that do
not carry DME/DME, the FAA is retaining a limited
network of VORs, called the VOR MON, to provide
a basic conventional navigation service for operators
to use if GNSS becomes unavailable. During a GNSSdisruption, the MON will enable aircraft to navigate
through the affected area or to a safe landing at a
MON airport without reliance on GNSS. Navigationusing the MON will not be as efficient as the new
PBN route structure, but use of the MON will provide
nearly continuous VOR signal coverage at 5,000 feet
AGL across the NAS, outside of the Western U.S.
Mountainous Area (WUSMA).
NOTE−
There is no plan to change the NAVAID and r oute structure
in the WUSMA.
The VOR MON has been retained principally for IFR
aircraft that are not equipped with DME/DMEavionics. However, VFR aircraft may use the MON
as desired. Aircraft equipped with DME/DME
navigation systems would, in most cases, useDME/DME to continue flight using RNA V to their
destination. However, these aircraft may, of course,
use the MON.
1. Distance to a MON airport. The VOR MON
will ensure that regardless of an aircraft’s position in
the contiguous United States (CONUS), a MON
airport (equipped with legacy ILS or VOR
approaches) will be within 100 nautical miles. These
airports are referred to as “MON airports” and will
have an ILS approach or a VOR approach if an ILS
is not available. VORs to support these approacheswill be retained in the VOR MON. MON airports are
charted on low −altitude en route charts and are
contained in the Chart Supplement U.S. and other
appropriate publications.
NOTE−
Any suitable airport can be used to land in the event of aVOR outage. For example, an airport with a DME −re-
quired ILS approach may be available and could be usedby aircraft that are equipped with DME. The intent of the
MON airport is to provide an approach that can be used by
aircraft without ADF or DME when radar may not be
available.
2. Navigating to an airport. The VOR MON
will retain sufficient VORs and increase VOR service
volume to ensure that pilots will have nearlycontinuous signal reception of a VOR when flying at
5,000 feet AGL. A key concept of the MON is to
ensure that an aircraft will always be within 100 NM
AIM 10/12/17
1−1−3 Navigation Aidsof an airport with an instrument approach that is not
dependent on GPS. (See paragraph 1 −1−8.) If the
pilot encounters a GPS outage, the pilot will be able
to proceed via VOR −to−VOR navigation at
5,000 feet AGL through the GPS outage area or to asafe landing at a MON airport or another suitable
airport, as appropriate. Nearly all VORs inside of the
WUSMA and outside the CONUS are being retained.
In these areas, pilots use the existing (Victor and Jet)
route structure and VORs to proceed through a GPS
outage or to a landing.
3. Using the VOR MON.
(a)In the case of a planned GPS outage (for
example, one that is in a published NOTAM), pilots
may plan to fly through the outage using the MON asappropriate and as cleared by A TC. Similarly, aircraft
not equipped with GPS may plan to fly and land using
the MON, as appropriate and as cleared by ATC.
NOTE−
In many cases, flying using the MON may involve a more
circuitous r oute than flying GPS −enabled RNAV.
(b)In the case of an unscheduled GPS outage,
pilots and ATC will need to coordinate the best
outcome for all aircraft. It is possible that a GPSoutage could be disruptive, causing high workload
and demand for ATC service. Generally, the VOR
MON concept will enable pilots to navigate through
the GPS outage or land at a MON airport or at another
airport that may have an appropriate approach or maybe in visual conditions.
(1)The VOR MON is a reversionary
service provided by the FAA for use by aircraft that
are unable to continue RNA V during a GPSdisruption. The FAA has not mandated that preflight
or inflight planning include provisions for GPS − or
WAAS−equipped aircraft to carry sufficient fuel to
proceed to a MON airport in case of an unforeseen
GPS outage. Specifically, flying to a MON airport as
a filed alternate will not be explicitly required. Of
course, consideration for the possibility of a GPS
outage is prudent during flight planning as ismaintaining proficiency with VOR navigation.
(2)Also, in case of a GPS outage, pilots
may coordinate with ATC and elect to continue
through the outage or land. The VOR MON isdesigned to ensure that an aircraft is within 100 NM
of an airport, but pilots may decide to proceed to any
appropriate airport where a landing can be made.WAAS users flying under Part 91 are not required to
carry VOR avionics. These users do not have the
ability or requirement to use the VOR MON. Prudent
flight planning, by these WAAS −only aircraft, should
consider the possibility of a GPS outage.
NOTE−
The F AA recognizes that non −GPS−based appr oaches will
be reduced when VORs are eliminated, and that most
airports with an instrument approach may only have GPS −
or WAAS −based approaches. Pilots flying GPS − or
WAAS−equipped air craft that also have VOR/ILS avionics
should be diligent to maintain proficiency in VOR and ILSapproaches in the event of a GPS outage.
1−1−4. VOR Receiver Check
a.The FAA VOR test facility (VOT) transmits a
test signal which provides users a convenient means
to determine the operational status and accuracy of a
VOR receiver while on the ground where a VOT islocated. The airborne use of VOT is permitted;
however, its use is strictly limited to those
areas/altitudes specifically authorized in the ChartSupplement U.S. or appropriate supplement.
b.To use the VOT service, tune in the VOT
frequency on your VOR receiver. With the Course
Deviation Indicator (CDI) centered, the omni −bear-
ing selector should read 0 degrees with the to/from
indication showing “from” or the omni −bearing
selector should read 180 degrees with the to/from
indication showing “to.” Should the VOR receiver
operate an RMI (Radio Magnetic Indicator), it willindicate 180 degrees on any omni −bearing selector
(OBS) setting. Two means of identification are used.
One is a series of dots and the other is a continuoustone. Information concerning an individual test signal
can be obtained from the local FSS.
c.Periodic VOR receiver calibration is most
important. If a receiver’s Automatic Gain Control or
modulation circuit deteriorates, it is possible for it to
display acceptable accuracy and sensitivity close into
the VOR or VOT and display out −of−tolerance
readings when located at greater distances where
weaker signal areas exist. The likelihood of this
deterioration varies between receivers, and isgenerally considered a function of time. The best
assurance of having an accurate receiver is periodic
calibration. Yearly intervals are recommended atwhich time an authorized repair facility should
recalibrate the receiver to the manufacturer’s
specifications.
AIM 10/12/17
1−1−4 Navigation Aidsd.Federal Aviation Regulations (14 CFR Sec-
tion 91.171) provides for certain VOR equipment
accuracy checks prior to flight under instrument
flight rules. To comply with this requirement and to
ensure satisfactory operation of the airborne system,the FAA has provided pilots with the following means
of checking VOR receiver accuracy:
1.VOT or a radiated test signal from an
appropriately rated radio repair station.
2.Certified airborne check points.
3.Certified check points on the airport surface.
e.A radiated VOT from an appropriately rated
radio repair station serves the same purpose as an
FAA VOR signal and the check is made in much the
same manner as a VOT with the followingdifferences:
1.The frequency normally approved by the
Federal Communications Commission is
108.0 MHz.
2.Repair stations are not permitted to radiate the
VOR test signal continuously; consequently, the
owner or operator must make arrangements with the
repair station to have the test signal transmitted. This
service is not provided by all radio repair stations.
The aircraft owner or operator must determine which
repair station in the local area provides this service.A representative of the repair station must make an
entry into the aircraft logbook or other permanent
record certifying to the radial accuracy and the dateof transmission. The owner, operator or representat-
ive of the repair station may accomplish the necessary
checks in the aircraft and make a logbook entrystating the results. It is necessary to verify which test
radial is being transmitted and whether you should
get a “to” or “from” indication.
f.Airborne and ground check points consist of
certified radials that should be received at specific
points on the airport surface or over specific
landmarks while airborne in the immediate vicinity of
the airport.
1.Should an error in excess of plus or minus
4 degrees be indicated through use of a ground check,
or plus or minus 6 degrees using the airborne check,Instrument Flight Rules (IFR) flight must not be
attempted without first correcting the source of the
error.CAUTION −
No correction other than the correction card figuressupplied by the manufacturer should be applied in
making these VOR receiver checks.
2.Locations of airborne check points, ground
check points and VOTs are published in the ChartSupplement U.S.
3.If a dual system VOR (units independent of
each other except for the antenna) is installed in theaircraft, one system may be checked against the other.
Turn both systems to the same VOR ground facility
and note the indicated bearing to that station. The
maximum permissible variations between the two
indicated bearings is 4 degrees.
1−1−5. Tactical Air Navigation (TACAN)
a.For reasons peculiar to military or naval
operations (unusual siting conditions, the pitchingand rolling of a naval vessel, etc.) the civil
VOR/Distance Measuring Equipment (DME) system
of air navigation was considered unsuitable formilitary or naval use. A new navigational system,
TACAN, was therefore developed by the military and
naval forces to more readily lend itself to military and
naval requirements. As a result, the FAA has
integrated TACAN facilities with the civil VOR/
DME program. Although the theoretical, or technicalprinciples of operation of TACAN equipment are
quite dif ferent from those of VOR/DME facilities, the
end result, as far as the navigating pilot is concerned,
is the same. These integrated facilities are called
VORTACs.
b.TACAN ground equipment consists of either a
fixed or mobile transmitting unit. The airborne unit in
conjunction with the ground unit reduces thetransmitted signal to a visual presentation of both
azimuth and distance information. T ACAN is a pulse
system and operates in the Ultrahigh Frequency(UHF) band of frequencies. Its use requires TACAN
airborne equipment and does not operate through
conventional VOR equipment.
1−1−6. VHF Omni −directional
Range/Tactical Air Navigation (VORTAC)
a.A VORTAC is a facility consisting of two
components, VOR and TACAN, which providesthree individual services: VOR azimuth, TACAN
azimuth and TACAN distance (DME) at one site.
Although consisting of more than one component,
AIM 10/12/17
1−1−5 Navigation Aidsincorporating more than one operating frequency,
and using more than one antenna system, a VORTAC
is considered to be a unified navigational aid. Both
components of a VORTAC are envisioned as
operating simultaneously and providing the threeservices at all times.
b.Transmitted signals of VOR and TACAN are
each identified by three −letter code transmission and
are interlocked so that pilots using VOR azimuth with
TACAN distance can be assured that both signals
being received are definitely from the same groundstation. The frequency channels of the VOR and the
TACAN at each VORTAC facility are “paired” in
accordance with a national plan to simplify airborneoperation.
1−1−7. Distance Measuring Equipment
(DME)
a.In the operation of DME, paired pulses at a
specific spacing are sent out from the aircraft (this is
the interrogation) and are received at the groundstation. The ground station (transponder) then
transmits paired pulses back to the aircraft at the same
pulse spacing but on a different frequency. The timerequired for the round trip of this signal exchange is
measured in the airborne DME unit and is translated
into distance (nautical miles) from the aircraft to theground station.
b.Operating on the line −of−sight principle, DME
furnishes distance information with a very highdegree of accuracy. Reliable signals may be received
at distances up to 199 NM at line −of−sight altitude
with an accuracy of better than
1/2 mile or 3 percent
of the distance, whichever is greater. Distance
information received from DME equipment is
SLANT RANGE distance and not actual horizontaldistance.
c.Operating frequency range of a DME according
to ICAO Annex 10 is from 960 MHz to 1215 MHz.Aircraft equipped with TACAN equipment will
receive distance information from a VORTAC
automatically, while aircraft equipped with VORmust have a separate DME airborne unit.
d.VOR/DME, VORTAC, Instrument Landing
System (ILS)/DME, and localizer (LOC)/DMEnavigation facilities established by the FAA provide
course and distance information from collocated
components under a frequency pairing plan. Aircraftreceiving equipment which provides for automatic
DME selection assures reception of azimuth and
distance information from a common source when
designated VOR/DME, VORTAC, ILS/DME, and
LOC/DME are selected.
e.Due to the limited number of available
frequencies, assignment of paired frequencies isrequired for certain military noncollocated VOR and
TACAN facilities which serve the same area but
which may be separated by distances up to a fewmiles.
f.VOR/DME, VORTAC, ILS/DME, and LOC/
DME facilities are identified by synchronized
identifications which are transmitted on a time share
basis. The VOR or localizer portion of the facility isidentified by a coded tone modulated at 1020 Hz or
a combination of code and voice. The TACAN or
DME is identified by a coded tone modulated at1350 Hz. The DME or TACAN coded identification
is transmitted one time for each three or four times
that the VOR or localizer coded identification is
transmitted. When either the VOR or the DME is
inoperative, it is important to recognize whichidentifier is retained for the operative facility. A
single coded identification with a repetition interval
of approximately 30 seconds indicates that the DMEis operative.
g.Aircraft equipment which provides for auto-
matic DME selection assures reception of azimuth
and distance information from a common source
when designated VOR/DME, VORTAC and ILS/DME navigation facilities are selected. Pilots are
cautioned to disregard any distance displays from
automatically selected DME equipment when VORor ILS facilities, which do not have the DME feature
installed, are being used for position determination.
1−1−8. Navigational Aid (NAVAID) Service
Volumes
a.Most air navigation radio aids which provide
positive course guidance have a designated standardservice volume (SSV). The SSV defines the reception
limits of unrestricted NA VAIDs which are usable for
random/unpublished route navigation.
b.A NA V AID will be classified as restricted if it
does not conform to flight inspection signal strengthand course quality standards throughout the
published SSV . However, the NA VAID should not be
considered usable at altitudes below that which could
AIM 10/12/17
1−1−6 Navigation Aidsbe flown while operating under random route IFR
conditions (14 CFR Section 91.177), even though
these altitudes may lie within the designated SSV .
Service volume restrictions are first published in
Notices to Airmen (NOTAMs) and then with thealphabetical listing of the NA V AIDs in the Chart
Supplement U.S.
c.Standard Service V olume limitations do not
apply to published IFR routes or procedures.
d.VOR/DME/TACAN Standard Service V ol-
umes (SSV).
1.Standard service volumes (SSVs) are graphi-
cally shown in FIG 1−1−1, FIG 1−1−2, FIG 1−1−3,
FIG 1−1−4, and FIG 1−1−5. The SSV of a station is
indicated by using the class designator as a prefix tothe station type designation.
EXAMPLE −
TVOR, LDME, and HVORTAC.
FIG 1−1−1
Standard High Altitude Service Volume
(See FIG 1−1−5 for altitudes below 1,000 feet).
60,000 ft.100 NM
130 NM
45,000 ft.
18,000 ft.
14,500 ft.
1,000 ft. 40 NMFIG 1−1−2
Standard Low Altitude Service Volume
(See FIG 1−1−5 for altitudes below 1,000 feet).
NOTE: All elevations shown are with respect
to the station’s site elevation (AGL).Coverage is not available in a cone ofairspace directly above the facility.40 NM
18,000 ft.
1,000 ft.
2.Within 25 NM, the bottom of the T service
volume is defined by the curve in FIG 1 −1−4. Within
40 NM, the bottoms of the L and H service volumes
are defined by the curve in FIG 1 −1−5. (See
TBL 1−1−1.)
e.Nondirectional Radio Beacon (NDB)
1.NDBs are classified according to their
intended use.
2.The ranges of NDB service volumes are
shown in TBL 1 −1−2. The distances (radius) are the
same at all altitudes.
AIM 10/12/17
1−1−7 Navigation AidsTBL 1−1−1
VOR/DME/TACAN Standard Service Volumes
SSV Class Designator Altitude and Range Boundaries
T (Terminal) ........ From 1,000 feet above ground level (AGL) up to and including 12,000 feet AGL at radial distances out
to 25 NM.
L (Low Altitude) .... From 1,000 feet AGL up to and including 18,000 feet AGL at radial distances out to 40 NM.
H (High Altitude) .... From 1,000 feet AGL up to and including 14,500 feet AGL at radial distances out to 40 NM. From
14,500 AGL up to and inc luding 60,000 feet at radial distances out to 100 NM. From 18,000 feet AGL
up to and including 45,000 feet AGL at radial distances out to 130 NM.
TBL 1−1−2
NDB Service Volumes
Class Distance (Radius)
Compass Locator 15 NM
MH 25 NM
H 50 NM*
HH 75 NM
*Service ranges of individual facilities may be less than 50 nautical miles (NM). Restrictions to service
volumes are first published as a Notice to Airmen and then with the alphabetical listing of the NAVAID in
the Chart Supplement U.S.
FIG 1−1−3
Standard Terminal Service Volume
(See FIG 1−1−4 for altitudes below 1,000 feet).
25 NM
12,000 ft.
1,000 ft.
AIM 10/12/17
1−1−8 Navigation AidsFIG 1−1−4
Service Volume Lower Edge Terminal
0 5 10 15 20 25
DISTANCE TO THE STATION IN NMALTITUDE IN FEET
FIG 1−1−5
Service Volume Lower Edge
Standard High and Low
0 1 02 03 04 0
DISTANCE TO THE STATION IN NMALTITUDE IN FEET
1−1−9. Instrument Landing System (ILS)
a. General
1.The ILS is designed to provide an approach
path for exact alignment and descent of an aircraft on
final approach to a runway.
2.The ground equipment consists of two highly
directional transmitting systems and, along the
approach, three (or fewer) marker beacons. The
directional transmitters are known as the localizerand glide slope transmitters.3.The system may be divided functionally into
three parts:
(a) Guidance information: localizer, glide
slope;
(b) Range information: marker beacon,
DME; and
(c) Visual information: approach lights,
touchdown and centerline lights, runway lights.
4.Precision radar, or compass locators located
at the Outer Marker (OM) or Middle Marker (MM),may be substituted for marker beacons. DME, when
AIM 10/12/17
1−1−9 Navigation Aidsspecified in the procedure, may be substituted for the
OM.
5.Where a complete ILS system is installed on
each end of a runway; (i.e., the approach end of
Runway 4 and the approach end of Runway 22) the
ILS systems are not in service simultaneously.
b. Localizer
1.The localizer transmitter operates on one of
40 ILS channels within the frequency range of
108.10 to 11 1.95 MHz. Signals provide the pilot with
course guidance to the runway centerline.
2.The approach course of the localizer is called
the front course and is used with other functional
parts, e.g., glide slope, marker beacons, etc. Thelocalizer signal is transmitted at the far end of the
runway. It is adjusted for a course width of (full scale
fly−left to a full scale fly −right) of 700 feet at the
runway threshold.
3.The course line along the extended centerline
of a runway, in the opposite direction to the front
course is called the back course.
CAUTION −
Unless the aircraft’s ILS equipment includes reverse
sensing capability, when flying inbound on the back
course it is necessary to steer the aircraft in the direction
opposite the needle deflection when making corrections
from off−course to on −course. This “flying away from the
needle” is also required when flying outbound on thefront course of the localizer. Do not use back course
signals for approach unless a back course approach
procedure is published for that particular runway and the
approach is authorized by ATC.
4.Identification is in International Morse Code
and consists of a three −letter identifier preceded by
the letter I ( /C0068/C0068) transmitted on the localizer
frequency.
EXAMPLE −
I−DIA
5.The localizer provides course guidance
throughout the descent path to the runway thresholdfrom a distance of 18 NM from the antenna between
an altitude of 1,000 feet above the highest terrain
along the course line and 4,500 feet above theelevation of the antenna site. Proper off −course
indications are provided throughout the following
angular areas of the operational service volume:(a)To 10 degrees either side of the course
along a radius of 18 NM from the antenna; and
(b)From 10 to 35 degrees either side of the
course along a radius of 10 NM. (See FIG 1−1−6.)
FIG 1−1−6
Limits of Localizer Coverage
RUNWAYRUNWAY
LOCALIZER
ANTENNALOCALIZER
ANTENNA10 NM10 N M 18 NM18 N M
NORMAL LIMITS OF LOCALIZER
COVERAGE: THE SAME AREAAPPLIES TO A BACK COURSEWHEN PROVIDED.NORMAL LIMITS OF LOCALIZER
COVERAGE: THE SAME AREA
APPLIES TO A BACK COURSE
WHEN PROVIDED.10°10°
35°35°
6.Unreliable signals may be received outside
these areas.
c. Localizer Type Directional Aid (LDA)
1.The LDA is of comparable use and accuracy
to a localizer but is not part of a complete ILS. TheLDA course usually provides a more precise
approach course than the similar Simplified
Directional Facility (SDF) installation, which mayhave a course width of 6 or 12 degrees.
2.The LDA is not aligned with the runway.
Straight−in minimums may be published where
alignment does not exceed 30 degrees between thecourse and runway. Circling minimums only are
published where this alignment exceeds 30 degrees.
3.A very limited number of LDA approaches
also incorporate a glideslope. These are annotated in
the plan view of the instrument approach chart witha note, “LDA/Glideslope.” These procedures fall
under a newly defined category of approaches called
Approach with V ertical Guidance (APV) described in
paragraph 5 −4−5, Instrument Approach Procedure
Charts, subparagraph a7(b), Approach with Vertical
Guidance (APV). LDA minima for with and without
glideslope is provided and annotated on the minima
lines of the approach chart as S −LDA/GS and
S−LDA. Because the final approach course is not
aligned with the runway centerline, additional
maneuvering will be required compared to an ILS
approach.
AIM 10/12/17
1−1−10 Navigation Aidsd. Glide Slope/Glide Path
1.The UHF glide slope transmitter, operating
on one of the 40 ILS channels within the frequencyrange 329.15 MHz, to 335.00 MHz radiates its signals
in the direction of the localizer front course. The term
“glide path” means that portion of the glide slope that
intersects the localizer.
CAUTION −
False glide slope signals may exist in the area of the
localizer back course approach which can cause the glide
slope flag alarm to disappear and present unreliable glide
slope information. Disregard all glide slope signal
indications when making a localizer back course
approach unless a glide slope is specified on the approach
and landing chart.
2.The glide slope transmitter is located between
750 feet and 1,250 feet from the approach end of the
runway (down the runway) and of fset 250 to 650 feet
from the runway centerline. It transmits a glide path
beam 1.4 degrees wide (vertically). The signal
provides descent information for navigation down to
the lowest authorized decision height (DH) specified
in the approved ILS approach procedure. The
glidepath may not be suitable for navigation belowthe lowest authorized DH and any reference to
glidepath indications below that height must be
supplemented by visual reference to the runway
environment. Glidepaths with no published DH are
usable to runway threshold.
3.The glide path projection angle is normally
adjusted to 3 degrees above horizontal so that it
intersects the MM at about 200 feet and the OM atabout 1,400 feet above the runway elevation. The
glide slope is normally usable to the distance of
10 NM. However, at some locations, the glide slopehas been certified for an extended service volume
which exceeds 10 NM.
4.Pilots must be alert when approaching the
glidepath interception. False courses and reverse
sensing will occur at angles considerably greater than
the published path.
5.Make every effort to remain on the indicated
glide path.
CAUTION −
Avoid flying below the glide path to assure
obstacle/terrain clearance is maintained.
6.The published glide slope threshold crossing
height (TCH) DOES NOT represent the height of theactual glide path on −course indication above the
runway threshold. It is used as a reference for
planning purposes which represents the height above
the runway threshold that an aircraft’s glide slope
antenna should be, if that aircraft remains on atrajectory formed by the four −mile−to−middle
marker glidepath segment.
7.Pilots must be aware of the vertical height
between the aircraft’s glide slope antenna and the
main gear in the landing configuration and, at the DH,
plan to adjust the descent angle accordingly if the
published TCH indicates the wheel crossing height
over the runway threshold may not be satisfactory.Tests indicate a comfortable wheel crossing height is
approximately 20 to 30 feet, depending on the type of
aircraft.
NOTE−
The TCH for a runway is established based on several
factors including the largest aircraft category that
normally uses the runway, how airport layout affects theglide slope antenna placement, and terrain. A higher than
optimum TCH, with the same glide path angle, may cause
the aircraft to touch down further from the threshold if the
trajectory of the approach is maintained until the flare.
Pilots should consider the effect of a high TCH on therunway available for stopping the aircraft.
e. Distance Measuring Equipment (DME)
1.When installed with the ILS and specified in
the approach procedure, DME may be used:
(a)In lieu of the OM;
(b)As a back course (BC) final approach fix
(FAF); and
(c)To establish other fixes on the localizer
course.
2.In some cases, DME from a separate facility
may be used within Terminal Instrument Procedures(TERPS) limitations:
(a)To provide ARC initial approach seg-
ments;
(b)As a FAF for BC approaches; and
(c)As a substitute for the OM.
f. Marker Beacon
1.ILS marker beacons have a rated power
output of 3 watts or less and an antenna arraydesigned to produce an elliptical pattern with
dimensions, at 1,000 feet above the antenna, of
approximately 2,400 feet in width and 4,200 feet in
AIM 10/12/17
1−1−11 Navigation Aidslength. Airborne marker beacon receivers with a
selective sensitivity feature should always be
operated in the “low” sensitivity position for proper
reception of ILS marker beacons.
2.Ordinarily, there are two marker beacons
associated with an ILS, the OM and MM. Locations
with a Category II ILS also have an Inner
Marker (IM). When an aircraft passes over a marker,
the pilot will receive the indications shown inTBL 1−1−3.
(a)The OM normally indicates a position at
which an aircraft at the appropriate altitude on the
localizer course will intercept the ILS glide path.
(b)The MM indicates a position approxi-
mately 3,500 feet from the landing threshold. This is
also the position where an aircraft on the glide path
will be at an altitude of approximately 200 feet above
the elevation of the touchdown zone.
(c)The IM will indicate a point at which an
aircraft is at a designated decision height (DH) on the
glide path between the MM and landing threshold.
TBL 1−1−3
Marker Passage Indications
Marker Code Light
OM /C0042 /C0042 /C0042 BLUE
MM /C0068 /C0042 /C0068 /C0042 AMBER
IM /C0068 /C0068 /C0068 /C0068 WHITE
BC /C0068 /C0068 /C0068 /C0068 WHITE
3.A back course marker normally indicates the
ILS back course final approach fix where approach
descent is commenced.
g. Compass Locator
1.Compass locator transmitters are often
situated at the MM and OM sites. The transmittershave a power of less than 25 watts, a range of at least
15 miles and operate between 190 and 535 kHz. At
some locations, higher powered radio beacons, up to400 watts, are used as OM compass locators. These
generally carry Transcribed Weather Broadcast
(TWEB) information.
2.Compass locators transmit two letter identi-
fication groups. The outer locator transmits the first
two letters of the localizer identification group, andthe middle locator transmits the last two letters of the
localizer identification group.
h. ILS Frequency (See TBL 1 −1−4.)
TBL 1−1−4
Frequency Pairs Allocated for ILS
Localizer MHz Glide Slope
108.10 334.70
108.15 334.55
108.35 333.95
108.55 329.75
108.75 330.35
108.95 329.15
109.15 331.25
109.35 331.85
109.50 332.60
109.55 332.45
109.70 333.20
109.75 333.05
109.90 333.80
109.95 333.65
110.15 334.25
110.35 334.85
110.55 329.45
Localizer MHz Glide Slope
110.70 330.20
110.75 330.05
110.90 330.80
110.95 330.65
111.10 331.70
111.15 331.55
111.30 332.30
111.35 332.15
111.55 332.75
111.75 333.35
111.95 330.95
AIM 10/12/17
1−1−12 Navigation Aidsi. ILS Minimums
1.The lowest authorized ILS minimums, with
all required ground and airborne systems components
operative, are:
(a) Category I. Decision Height (DH)
200 feet and Runway Visual Range (RVR) 2,400 feet
(with touchdown zone and centerline lighting, RVR1,800 feet), or (with Autopilot or FD or HUD, RVR
1,800 feet);
(b) Special Authorization Category I.
DH 150 feet and Runway Visual Range (RVR) 1,400feet, HUD to DH;
(c) Category II. DH 100 feet and RVR 1,200
feet (with autoland or HUD to touchdown and noted
on authorization, RVR 1,000 feet);
(d) Special Authorization Category II with
Reduced Lighting. DH 100 feet and RVR 1,200 feet
with autoland or HUD to touchdown and noted on
authorization (touchdown zone, centerline lighting,
and ALSF −2 are not required);
(e) Category IIIa. No DH or DH below 100
feet and RVR not less than 700 feet;
(f) Category IIIb. No DH or DH below 50
feet and RVR less than 700 feet but not less than 150
feet; and
(g) Category IIIc. No DH and no RVR
limitation.
NOTE−
Special authorization and equipment required for
Categories II and III.
j. Inoperative ILS Components
1. Inoperative localizer. When the localizer
fails, an ILS approach is not authorized.
2. Inoperative glide slope. When the glide
slope fails, the ILS reverts to a non −precision
localizer approach.
REFERENCE−
See the inoperative component table in the U.S. Government Terminal
Procedures Publication (TPP), for adjustments to minimums due to
inoperative airborne or ground system equipment.
k. ILS Course Distortion
1.All pilots should be aware that disturbances to
ILS localizer and glide slope courses may occur when
surface vehicles or aircraft are operated near the
localizer or glide slope antennas. Most ILSinstallations are subject to signal interference by
either surface vehicles, aircraft or both. ILS
CRITICAL AREAS are established near each
localizer and glide slope antenna.
2.ATC issues control instructions to avoid
interfering operations within ILS critical areas atcontrolled airports during the hours the Airport
Traffic Control Tower (ATCT) is in operation as
follows:
(a) Weather Conditions. Official weather
observation is a ceiling of less than 800 feet and/or
visibility 2 miles.
(1) Localizer Critical Area. Except for
aircraft that land, exit a runway, depart, or execute a
missed approach, vehicles and aircraft are not
authorized in or over the critical area when an arriving
aircraft is inside the outer marker (OM) or the fix
used in lieu of the OM. Additionally, whenever the
official weather observation is a ceiling of less than
200 feet or R VR less than 2,000 feet, do not authorize
vehicles or aircraft operations in or over the area
when an arriving aircraft is inside the MM, or in the
absence of a MM, ½ mile final.
(2) Glide Slope Critical Area. Do not
authorize vehicles or aircraft operations in or over the
area when an arriving aircraft is inside the ILS outer
marker (OM), or the fix used in lieu of the OM, unless
the arriving aircraft has reported the runway in sight
and is circling or side −stepping to land on another
runway.
(b) Weather Conditions. At or above ceil-
ing 800 feet and/or visibility 2 miles.
(1)No critical area protective action is
provided under these conditions.
(2)A flight crew, under these conditions,
should advise the tower that it will conduct anAUTOLAND or COUPLED approach.
EXAMPLE−
Denver Tower, United 1153, Request Autoland/CoupledApproach (runway)ATC replies with:United 1153, Denver Tower, Roger, Critical Areas not
protected.
3.Aircraft holding below 5,000 feet between
the outer marker and the airport may cause localizer
signal variations for aircraft conducting the ILS
approach. Accordingly, such holding is not autho-
AIM 10/12/17
1−1−13 Navigation Aidsrized when weather or visibility conditions are less
than ceiling 800 feet and/or visibility 2 miles.
4.Pilots are cautioned that vehicular traffic not
subject to ATC may cause momentary deviation toILS course or glide slope signals. Also, critical areas
are not protected at uncontrolled airports or at airports
with an operating control tower when weather or
visibility conditions are above those requiring
protective measures. Aircraft conducting coupled orautoland operations should be especially alert in
monitoring automatic flight control systems.
(See FIG 1−1−7.)
NOTE−
Unless otherwise coordinated through Flight Standards,
ILS signals to Category I runways are not flight inspected
below the point that is 100 feet less than the decisionaltitude (DA). Guidance signal anomalies may beencountered below this altitude.
1−1−10. Simplified Directional Facility
(SDF)
a.The SDF provides a final approach course
similar to that of the ILS localizer. It does not provide
glide slope information. A clear understanding of the
ILS localizer and the additional factors listed below
completely describe the operational characteristicsand use of the SDF.
b.The SDF transmits signals within the range of
108.10 to 111.95 MHz.c.The approach techniques and procedures used
in an SDF instrument approach are essentially the
same as those employed in executing a standard
localizer approach except the SDF course may not be
aligned with the runway and the course may be wider,
resulting in less precision.
d.Usable off −course indications are limited to
35 degrees either side of the course centerline.Instrument indications received beyond 35 degrees
should be disregarded.
e.The SDF antenna may be of fset from the runway
centerline. Because of this, the angle of convergence
between the final approach course and the runway
bearing should be determined by reference to theinstrument approach procedure chart. This angle is
generally not more than 3 degrees. However, it should
be noted that inasmuch as the approach courseoriginates at the antenna site, an approach which is
continued beyond the runway threshold will lead the
aircraft to the SDF offset position rather than alongthe runway centerline.
f.The SDF signal is fixed at either 6 degrees or
12 degrees as necessary to provide maximumflyability and optimum course quality.
g.Identification consists of a three −letter identifi-
er transmitted in Morse Code on the SDF frequency.The appropriate instrument approach chart will
indicate the identifier used at a particular airport.
AIM 10/12/17
1−1−14 Navigation AidsFIG 1−1−7
FAA Instrument Landing Systems
AIM 10/12/17
1−1−15 Navigation Aids1−1−11. NAVAID Identifier Removal During
Maintenance
During periods of routine or emer gency maintenance,
coded identification (or code and voice, whereapplicable) is removed from certain F AA NA V AIDs.
Removal of identification serves as a warning to
pilots that the facility is officially off the air fortune−up or repair and may be unreliable even though
intermittent or constant signals are received.
NOTE−
During periods of maintenance VHF ranges may radiate
a T−E−S−T code ( -/C0068 /C0068/C0068/C0068 -).
NOTE−
DO NOT attempt to fly a procedure that is NOTAMed out
of service even if the identification is present. In certaincases, the identification may be transmitted for shortperiods as part of the testing.
1−1−12. NAVAIDs with Voice
a.V oice equipped en route radio navigational aids
are under the operational control of either a Flight
Service Station (FSS) or an approach control facility.
The voice communication is available on some
facilities. Hazardous Inflight Weather Advisory
Service (HIWAS) broadcast capability is available on
selected VOR sites throughout the conterminous U.S.
and does not provide two-way voice communication.
The availability of two-way voice communicationand HIWAS is indicated in the Chart Supplement
U.S. and aeronautical charts.
b.Unless otherwise noted on the chart, all radio
navigation aids operate continuously except during
shutdowns for maintenance. Hours of operation of
facilities not operating continuously are annotated on
charts and in the Chart Supplement U.S.
1−1−13. User Reports Requested on
NAVAID or Global Navigation SatelliteSystem (GNSS) Performance or
Interference
a.Users of the National Airspace System (NAS)
can render valuable assistance in the early correctionof NA VAID malfunctions or GNSS problems and are
encouraged to report their observations of undesir-
able avionics performance. Although NA V AIDs aremonitored by electronic detectors, adverse effects of
electronic interference, new obstructions, or changes
in terrain near the NA V AID can exist withoutdetection by the ground monitors. Some of the
characteristics of malfunction or deteriorating
performance which should be reported are: erratic
course or bearing indications; intermittent, or full,
flag alarm; garbled, missing or obviously impropercoded identification; poor quality communications
reception; or, in the case of frequency interference, an
audible hum or tone accompanying radio communi-cations or NA V AID identification. GNSS problems
are often characterized by navigation degradation or
service loss indications. For instance, pilots conduct-
ing operations in areas where there is GNSS
interference may be unable to use GPS for navigation,
and ADS −B may be unavailable for surveillance.
Radio frequency interference may affect both
navigation for the pilot and surveillance by the air
traffic controller. Depending on the equipment andintegration, either an advisory light or message may
alert the pilot. Air traffic controllers monitoring
ADS−B reports may stop receiving ADS −B position
messages and associated aircraft tracks.
In addition, malfunctioning, faulty, inappropriately
installed, operated, or modified GPS re −radiator
systems, intended to be used for aircraft maintenance
activities, have resulted in unintentional disruption
of aviation GNSS receivers. This type of disruption
could result in un −flagged, erroneous position
information output to primary flight displays/indica-
tors and to other aircraft and air traffic control
systems. Since receiver autonomous integrity
monitoring (RAIM) is only partially effective against
this type of disruption (effectively a “signal
spoofing”), the pilot may not be aware of any
erroneous navigation indications; ATC may be theonly means available for identification of these
disruptions and detect unexpected aircraft position
while monitoring aircraft for IFR separation.
b.Pilots reporting potential interference should
identify the NA V AID (for example, VOR) malfunc-
tion or GNSS problem, location of the aircraft (that is,
latitude, longitude or bearing/distance from a
reference NA VAID), magnetic heading, altitude, date
and time of the observation, type of aircraft(make/model/call sign), and description of the
condition observed, and the type of receivers in use
(that is, make/model/software revision). Reports can
be made in any of the following ways:
1.Immediately, by voice radio communication
to the controlling ATC facility or FSS.
AIM 10/12/17
1−1−16 Navigation Aids2.By telephone to the nearest ATC facility
controlling the airspace where the disruption was
experienced.
3.Additionally, GNSS problems may be
reported by Internet via the GPS Anomaly Reporting
Form at http://www.faa.gov/air_traffic/nas/
gps_reports/ .
c.In aircraft equipped with more than one avionics
receiver, there are many combinations of potential
interference between units that could causeerroneous navigation indications, or complete or
partial blanking out of the display.
NOTE−
GPS interference or outages associated with known
testing NOTAMs should not be reported to ATC.
1−1−14. LORAN
NOTE−
In accordance with the 2010 DHS Appropriations Act, the
U.S. Coast Guard (USCG) terminated the transmission of
all U.S. LORAN −C signals on 08 Feb 2010. The USCG also
terminated the transmission of the Russian Americansignals on 01 Aug 2010, and the Canadian LORAN −C
signals on 03 Aug 2010. For more information, visit
http://www.navcen.uscg.gov. Operators should also note
that TSO −C60b, AIRBORNE AREA NAVIGATION
EQUIPMENT USING LORAN −C INPUTS, has been
canceled by the F AA.
1−1−15. Inertial Reference Unit (IRU),
Inertial Navigation System (INS), and
Attitude Heading Reference System (AHRS)
a.IRUs are self −contained systems comprised of
gyros and accelerometers that provide aircraft
attitude (pitch, roll, and heading), position, and
velocity information in response to signals resultingfrom inertial effects on system components. Once
aligned with a known position, IRUs continuously
calculate position and velocity. IRU positionaccuracy decays with time. This degradation is
known as “drift.”
b.INSs combine the components of an IRU with
an internal navigation computer. By programming a
series of waypoints, these systems will navigate along
a predetermined track.
c.AHRSs are electronic devices that provide
attitude information to aircraft systems such asweather radar and autopilot, but do not directly
compute position information.
d.Aircraft equipped with slaved compass systems
may be susceptible to heading errors caused by
exposure to magnetic field disturbances (flux fields)
found in materials that are commonly located on thesurface or buried under taxiways and ramps. These
materials generate a magnetic flux field that can be
sensed by the aircraft’s compass system flux detector
or “gate”, which can cause the aircraft’s system to
align with the material’s magnetic field rather than
the earth’s natural magnetic field. The system’serroneous heading may not self-correct. Prior to take
off pilots should be aware that a heading
misalignment may have occurred during taxi. Pilotsare encouraged to follow the manufacturer’s or other
appropriate procedures to correct possible heading
misalignment before take off is commenced.
1−1−16. Doppler Radar
Doppler Radar is a semiautomatic self −contained
dead reckoning navigation system (radar sensor plus
computer) which is not continuously dependent oninformation derived from ground based or external
aids. The system employs radar signals to detect and
measure ground speed and drift angle, using the
aircraft compass system as its directional reference.
Doppler is less accurate than INS, however, and theuse of an external reference is required for periodic
updates if acceptable position accuracy is to be
achieved on long range flights.
1−1−17. Global Positioning System (GPS)
a. System Overview
1.System Description. The Global Positioning
System is a space-based radio navigation system
used to determine precise position anywhere in theworld. The 24 satellite constellation is designed to
ensure at least five satellites are always visible to a
user worldwide. A minimum of four satellites isnecessary for receivers to establish an accurate
three−dimensional position. The receiver uses data
from satellites above the mask angle (the lowestangle above the horizon at which a receiver can use
a satellite). The Department of Defense (DOD) is
responsible for operating the GPS satellite constella-
tion and monitors the GPS satellites to ensure proper
operation. Each satellite’s orbital parameters (eph-
emeris data) are sent to each satellite for broadcast as
AIM 10/12/17
1−1−17 Navigation Aidspart of the data message embedded in the GPS signal.
The GPS coordinate system is the Cartesian
earth−centered, earth −fixed coordinates as specified
in the World Geodetic System 1984 (WGS −84).
2.System Availability and Reliability.
(a)The status of GPS satellites is broadcast as
part of the data message transmitted by the GPS
satellites. GPS status information is also available by
means of the U.S. Coast Guard navigation
information service: (703) 313 −5907, Internet:
http://www.navcen.uscg.gov/ . Additionally, satel-
lite status is available through the Notice to Airmen
(NOTAM) system.
(b)GNSS operational status depends on the
type of equipment being used. For GPS −only
equipment TSO −C129 or TSO-C196(), the opera-
tional status of non −precision approach capability for
flight planning purposes is provided through a
prediction program that is embedded in the receiveror provided separately.
3.Receiver Autonomous Integrity Monitoring
(RAIM). RAIM is the capability of a GPS receiver to
perform integrity monitoring on itself by ensuringavailable satellite signals meet the integrity require-
ments for a given phase of flight. W ithout RAIM, the
pilot has no assurance of the GPS position integrity.RAIM provides immediate feedback to the pilot. This
fault detection is critical for performance-based
navigation (PBN)(see Paragraph 1 −2−1, Perform-
ance−Based Navigation (PBN) and Area Navigation
(RNA V), for an introduction to PBN), because delays
of up to two hours can occur before an erroneoussatellite transmission is detected and corrected by the
satellite control segment.
(a)In order for RAIM to determine if a
satellite is providing corrupted information, at leastone satellite, in addition to those required for
navigation, must be in view for the receiver to
perform the RAIM function. RAIM requires aminimum of 5 satellites, or 4 satellites and barometric
altimeter input (baro −aiding), to detect an integrity
anomaly. Baro−aiding is a method of augmenting the
GPS integrity solution by using a non-satellite input
source in lieu of the fifth satellite. Some GPS
receivers also have a RAIM capability, called faultdetection and exclusion (FDE), that excludes a failed
satellite from the position solution; GPS receivers
capable of FDE require 6 satellites or 5 satellites withbaro−aiding. This allows the GPS receiver to isolate
the corrupt satellite signal, remove it from the
position solution, and still provide an integrity-as-
sured position. To ensure that baro −aiding is
available, enter the current altimeter setting into thereceiver as described in the operating manual. Do not
use the GPS derived altitude due to the large GPS
vertical errors that will make the integrity monitoring
function invalid.
(b)There are generally two types of RAIM
fault messages. The first type of message indicates
that there are not enough satellites available toprovide RAIM integrity monitoring. The GPS
navigation solution may be acceptable, but the
integrity of the solution cannot be determined. Thesecond type indicates that the RAIM integrity
monitor has detected a potential error and that there
is an inconsistency in the navigation solution for thegiven phase of flight. Without RAIM capability, the
pilot has no assurance of the accuracy of the GPS
position.
4.Selective Availability. Selective Availability
(SA) is a method by which the accuracy of GPS is
intentionally degraded. This feature was designed to
deny hostile use of precise GPS positioning data. SA
was discontinued on May 1, 2000, but many GPS
receivers are designed to assume that SA is still
active. New receivers may take advantage of thediscontinuance of SA based on the performance
values in ICAO Annex 10.
b. Operational Use of GPS. U.S. civil operators
may use approved GPS equipment in oceanicairspace, certain remote areas, the National Airspace
System and other States as authorized (please consult
the applicable Aeronautical Information Publica-tion). Equipage other than GPS may be required for
the desired operation. GPS navigation is used for both
Visual Flight Rules (VFR) and Instrument FlightRules (IFR) operations.
1. VFR Operations
(a)GPS navigation has become an asset to
VFR pilots by providing increased navigational
capabilities and enhanced situational awareness.Although GPS has provided many benefits to the
VFR pilot, care must be exercised to ensure that
system capabilities are not exceeded. VFR pilotsshould integrate GPS navigation with electronic
navigation (when possible), as well as pilotage and
dead reckoning.
AIM 10/12/17
1−1−18 Navigation Aids(b)GPS receivers used for VFR navigation
vary from fully integrated IFR/VFR installation used
to support VFR operations to hand −held devices.
Pilots must understand the limitations of the receivers
prior to using in flight to avoid misusing navigationinformation. (See TBL 1 −1−6.) Most receivers are
not intuitive. The pilot must learn the various
keystrokes, knob functions, and displays that areused in the operation of the receiver. Some
manufacturers provide computer −based tutorials or
simulations of their receivers that pilots can use tobecome familiar with operating the equipment.
(c)When using GPS for VFR operations,
RAIM capability, database currency, and antennalocation are critical areas of concern.
(1)RAIM Capability. VFR GPS panel
mount receivers and hand −held units have no RAIM
alerting capability. This prevents the pilot from being
alerted to the loss of the required number of satellites
in view, or the detection of a position error. Pilotsshould use a systematic cross −check with other
navigation techniques to verify position. Be
suspicious of the GPS position if a disagreementexists between the two positions.
(2)Database Currency. Check the curren-
cy of the database. Databases must be updated for
IFR operations and should be updated for all other
operations. However, there is no requirement fordatabases to be updated for VFR navigation. It is not
recommended to use a moving map with an outdated
database in and around critical airspace. Pilots using
an outdated database should verify waypoints using
current aeronautical products; for example, Chart
Supplement U.S., Sectional Chart, or En RouteChart.
(3)Antenna Location. The antenna loca-
tion for GPS receivers used for IFR and VFRoperations may differ. VFR antennae are typically
placed for convenience more than performance,
while IFR installations ensure a clear view isprovided with the satellites. Antennae not providing
a clear view have a greater opportunity to lose the
satellite navigational signal. This is especially truein the case of hand −held GPS receivers. Typically,
suction cups are used to place the GPS antennas on
the inside of cockpit windows. While this method hasgreat utility, the antenna location is limited to the
cockpit or cabin which rarely provides a clear view
of all available satellites. Consequently, signal lossesmay occur due to aircraft structure blocking satellite
signals, causing a loss of navigation capability. These
losses, coupled with a lack of RAIM capability, could
present erroneous position and navigation informa-
tion with no warning to the pilot. While the use of ahand−held GPS for VFR operations is not limited by
regulation, modification of the aircraft, such as
installing a panel − or yoke−mounted holder, is
governed by 14 CFR Part 43. Consult with your
mechanic to ensure compliance with the regulation
and safe installation.
(d)Do not solely rely on GPS for VFR
navigation. No design standard of accuracy or
integrity is used for a VFR GPS receiver. VFR GPSreceivers should be used in conjunction with other
forms of navigation during VFR operations to ensure
a correct route of flight is maintained. Minimizehead−down time in the aircraft by being familiar with
your GPS receiver’s operation and by keeping eyes
outside scanning for traffic, terrain, and obstacles.
(e) VFR Waypoints
(1)VFR waypoints provide VFR pilots
with a supplementary tool to assist with positionawareness while navigating visually in aircraft
equipped with area navigation receivers. VFR
waypoints should be used as a tool to supplement
current navigation procedures. The uses of VFR
waypoints include providing navigational aids for
pilots unfamiliar with an area, waypoint definition of
existing reporting points, enhanced navigation in and
around Class B and Class C airspace, and enhanced
navigation around Special Use Airspace. VFR pilots
should rely on appropriate and current aeronautical
charts published specifically for visual navigation. If
operating in a terminal area, pilots should takeadvantage of the Terminal Area Chart available for
that area, if published. The use of VFR waypoints
does not relieve the pilot of any responsibility tocomply with the operational requirements of 14 CFR
Part 91.
(2)VFR waypoint names (for computer −
entry and flight plans) consist of five letters
beginning with the letters “VP” and are retrievable
from navigation databases. The VFR waypointnames are not intended to be pronounceable, and they
are not for use in ATC communications. On VFR
charts, stand−alone VFR waypoint s will be portrayed
using the same four −point star symbol used for IFR
waypoints. VFR waypoints collocated with visual
check points on the chart will be identified by small
AIM 10/12/17
1−1−19 Navigation Aidsmagenta flag symbols. VFR waypoints collocated
with visual check points will be pronounceable based
on the name of the visual check point and may be used
for A TC communications. Each VFR waypoint name
will appear in parentheses adjacent to the geographic
location on the chart. Latitude/longitude data for all
established VFR waypoints may be found in the
appropriate regional Chart Supplement U.S.
(3)VFR waypoints may not be used on IFR
flight plans. VFR waypoints are not recognized by the
IFR system and will be rejected for IFR routingpurposes.
(4)Pilots may use the five −letter identifier
as a waypoint in the route of flight section on a VFRflight plan. Pilots may use the VFR waypoints only
when operating under VFR conditions. The point
may represent an intended course change or describethe planned route of flight. This VFR filing would be
similar to how a VOR would be used in a route of
flight.
(5)VFR waypoints intended for use during
flight should be loaded into the receiver while on the
ground. Once airborne, pilots should avoid program-
ming routes or VFR waypoint chains into their
receivers.
(6)Pilots should be vigilant to see and
avoid other traffic when near VFR waypoints. With
the increased use of GPS navigation and accuracy,
expect increased traffic near VFR waypoints.Regardless of the class of airspace, monitor the
available ATC frequency for traffic information on
other aircraft operating in the vicinity . See Paragraph
7−5−2, VFR in Congested Areas, for more
information.
2. IFR Use of GPS
(a) General Requirements. Authorization
to conduct any GPS operation under IFR requires:
(1)GPS navigation equipment used for IFR
operations must be approved in accordance with the
requirements specified in Technical Standard Order
(TSO) TSO −C129(), TSO −C196(), TSO −C145(), or
TSO−C146(), and the installation must be done in
accordance with Advisory Circular AC 20 −138,
Airworthiness Approval of Positioning and Naviga-tion Systems. Equipment approved in accordance
with TSO −C115a does not meet the requirements of
TSO−C129. V isual flight rules (VFR) and hand −heldGPS systems are not authorized for IFR navigation,
instrument approaches, or as a principal instrument
flight reference.
(2)Aircraft using un-augmented GPS
(TSO-C129() or TSO-C196()) for navigation under
IFR must be equipped with an alternate approved and
operational means of navigation suitable fornavigating the proposed route of flight. (Examples of
alternate navigation equipment include VOR or
DME/DME/IRU capability). Active monitoring ofalternative navigation equipment is not required
when RAIM is available for integrity monitoring.
Active monitoring of an alternate means ofnavigation is required when the GPS RAIM
capability is lost.
(3)Procedures must be established for use
in the event that the loss of RAIM capability ispredicted to occur. In situations where RAIM is
predicted to be unavailable, the flight must rely on
other approved navigation equipment, re-route towhere RAIM is available, delay departure, or cancel
the flight.
(4)
The GPS operation must be conducted
in accordance with the FAA −approved aircraft flight
manual (AFM) or flight manual supplement. Flight
crew members must be thoroughly familiar with the
particular GPS equipment installed in the aircraft, the
receiver operation manual, and the AFM or flight
manual supplement. Operation, receiver presenta-
tion and capabilities of GPS equipment vary. Due tothese differences, operation of GPS receivers of
different brands, or even models of the same brand,
under IFR should not be attempted without thorough
operational knowledge. Most receivers have a
built−in simulator mode, which allows the pilot to
become familiar with operation prior to attemptingoperation in the aircraft.
(5)Aircraft navigating by IFR −approved
GPS are considered to be performance −based
navigation (PBN) aircraft and have special equip-ment suffixes. File the appropriate equipment suffix
in accordance with TBL 5 −1−3 on the ATC flight
plan. If GPS avionics become inoperative, the pilotshould advise ATC and amend the equipment suf fix.
(6)Prior to any GPS IFR operation, the
pilot must review appropriate NOTAMs and
aeronautical information. (See GPS NOT AMs/Aero-
nautical Information).
AIM 10/12/17
1−1−20 Navigation Aids(b) Database Requirements. The onboard
navigation data must be current and appropriate for
the region of intended operation and should include
the navigation aids, waypoints, and relevant coded
terminal airspace procedures for the departure,arrival, and alternate airfields.
(1)Further database guidance for terminal
and en route requirements may be found in AC90-100, U.S. Terminal and En Route Area
Navigation (RNA V) Operations.
(2)Further database guidance on Required
Navigation Performance (RNP) instrument approach
operations, RNP terminal, and RNP en routerequirements may be found in AC 90-105, Approval
Guidance for RNP Operations and Barometric
Vertical Navigation in the U.S. National AirspaceSystem.
(3)All approach procedures to be flown
must be retrievable from the current airbornenavigation database supplied by the equipment
manufacturer or other FAA −approved source. The
system must be able to retrieve the procedure by name
from the aircraft navigation database, not just as a
manually entered series of waypoints. Manual entry
of waypoints using latitude/longitude or place/bear-ing is not permitted for approach procedures.
(4)Prior to using a procedure or waypoint
retrieved from the airborne navigation database, the
pilot should verify the validity of the database. This
verification should include the following preflightand inflight steps:
[a] Preflight:
[1] Determine the date of database
issuance, and verify that the date/time of proposed
use is before the expiration date/time.
[2] V erify that the database provider
has not published a notice limiting the use of the
specific waypoint or procedure.
[b] Inflight:
[1] Determine that the waypoints
and transition names coincide with names found on
the procedure chart. Do not use waypoints which do
not exactly match the spelling shown on publishedprocedure charts.
[2] Determine that the waypoints are
logical in location, in the correct order, and theirorientation to each other is as found on the procedure
chart, both laterally and vertically.
NOTE−
There is no specific requirement to check each waypointlatitude and longitude, type of waypoint and/or altitude
constraint, only the general relationship of waypoints in
the procedure, or the logic of an individual waypoint’ slocation.
[3] If the cursory check of procedure
logic or individual waypoint location, specified in [b]
above, indicates a potential error, do not use theretrieved procedure or waypoint until a verification of
latitude and longitude, waypoint type, and altitude
constraints indicate full conformity with the
published data.
(5)Air carrier and commercial operators
must meet the appropriate provisions of theirapproved operations specifications.
[a]During domestic operations for com-
merce or for hire, operators must have a secondnavigation system capable of reversion or contin-
gency operations.
[b]Operators must have two independ-
ent navigation systems appropriate to the route to beflown, or one system that is suitable and a second,
independent backup capability that allows the
operator to proceed safely and land at a different
airport, and the aircraft must have sufficient fuel
(reference 14 CFR 121.349, 125.203, 129.17, and135.165). These rules ensure the safety of the
operation by preventing a single point of failure.
NOTE−
An aircraft approved for multi-sensor navigation andequipped with a single navigation system must maintain an
ability to navigate or proceed safely in the event that any
one component of the navigation system fails, including the
flight management system (FMS). Retaining a FMS-inde-pendent VOR capability would satisfy this requirement.
[c]The requirements for a second
system apply to the ent ire set of equipment needed to
achieve the navigation capability, not just theindividual components of the system such as the radio
navigation receiver. For example, to use two RNA V
systems (e.g., GPS and DME/DME/IRU) to complywith the requirements, the aircraft must be equipped
with two independent radio navigation receivers and
two independent navigation computers (e.g., flightmanagement systems (FMS)). Alternatively, to
comply with the requirements using a single RNA V
system with an installed and operable VOR
AIM 10/12/17
1−1−21 Navigation Aidscapability, the VOR capability must be independent
of the FMS.
[d]To satisfy the requirement for two
independent navigation systems, if the primarynavigation system is GPS −based, the second system
must be independent of GPS (for example, VOR or
DME/DME/IRU). This allows continued navigationin case of failure of the GPS or WAAS services.
Recognizing that GPS interference and test events
resulting in the loss of GPS services have becomemore common, the FAA requires operators conduct-
ing IFR operations under 14 CFR 121.349, 125.203,
129.17 and 135.65 to retain a non-GPS navigationcapability consisting of either DME/DME, IRU, or
VOR for en route and terminal operations, and VOR
and ILS for final app roach. Since this system is to be
used as a reversionary capability, single equipage is
sufficient.
3. Oceanic, Domestic, En Route, and
Terminal Area Operations
(a)Conduct GPS IFR operations in oceanic
areas only when approved avionics systems are
installed. TSO −C196() users and TSO −C129() GPS
users authorized for Class A1, A2, B1, B2, C1, or C2
operations may use GPS in place of another approved
means of long −range navigation, such as dual INS.
(See TBL 1 −1−5 and TBL 1 −1−6.) Aircraft with a
single installation GPS, meeting the above specifica-
tions, are authorized to operate on short oceanic
routes requiring one means of long −range navigation
(reference AC 20-138, Appendix 1).
(b)Conduct GPS domestic, en route, and
terminal IFR operations only when approved
avionics systems are installed. Pilots may use GPS
via TSO−C129() authorized for Class A1, B1, B3,
C1, or C3 operations GPS via TSO-C196(); or
GPS/WAAS with either TSO-C145() orTSO-C146(). When using TSO-C129() or
TSO-C196() receivers, the avionics n ecessary to
receive all of the ground −based facilities appropriate
for the route to the destination airport and any
required alternate airport must be installed and
operational. Ground −based facilities necessary for
these routes must be operational.
(1)GPS en route IFR operations may be
conducted in Alaska outside the operational service
volume of ground −based navigation aids when a
TSO−C145() or TSO −C146() GPS/wide area aug-mentation system (WAAS) system is installed and
operating. WAAS is the U.S. version of a
satellite-based augmentation system (SBAS).
[a]In Alaska, aircraft may operate on
GNSS Q-routes with GPS (TSO-C129 () or
TSO-C196 ()) equipment while the aircraft remains
in Air Traffic Control (ATC) radar surveillance orwith GPS/WAAS (TSO-C145 () or TSO-C146 ())
which does not require ATC radar surveillance.
[b]In Alaska, aircraft may only operate
on GNSS T -routes with GPS/WAAS (TSO-C145 () or
TSO-C146 ()) equipment.
(2)Ground−based navigation equipment
is not required to be installed and operating for en
route IFR operations when using GPS/W AAS
navigation systems. All operators should ensure that
an alternate means of navigation is available in the
unlikely event the GPS/W AAS navigation system
becomes inoperative.
(3)Q-routes and T-routes outside Alaska.
Q-routes require system performance currently met
by GPS, GPS/WAAS, or DME/DME/IRU RNA V
systems that satisfy the criteria discussed in AC90−100, U.S. Terminal and En Route Area
Navigation (RNA V) Operations. T-routes require
GPS or GPS/WAAS equipment.
REFERENCE −
AIM, Paragraph 5 −3−4 , Airways and Route Systems
(c)GPS IFR approach/departure operations
can be conducted when approved avionics systems
are installed and the following requirements are met:
(1)The aircraft is TSO −C145() or TSO −
C146() or TSO −C196() or TSO −C129() in Class A1,
B1, B3, C1, or C3; and
(2)The approach/departure must be re-
trievable from the current airborne navigation
database in the navigation computer. The system
must be able to retrieve the procedure by name fromthe aircraft navigation database. Manual entry of
waypoints using latitude/longitude or place/bearing
is not permitted for approach procedures.
(3)The authorization to fly instrument
approaches/departures with GPS is limited to U.S.
airspace.
(4)The use of GPS in any other airspace
must be expressly authorized by the FAA Adminis-
trator.
AIM 10/12/17
1−1−22 Navigation Aids(5)GPS instrument approach/departure
operations outside the U.S. must be authorized by
the appropriate sovereign authority.
4. Departures and Instrument Departure
Procedures (DPs)
The GPS receiver must be set to terminal ( ±1 NM)
CDI sensitivity and the navigation routes contained in
the database in order to fly published IFR charteddepartures and DPs. Terminal RAIM should be
automatically provided by the receiver. (Terminal
RAIM for departure may not be available unless thewaypoints are part of the active flight plan rather than
proceeding direct to the fi rst destination.) Certain
segments of a DP may require some manualintervention by the pilot, especially when radar
vectored to a course or required to intercept a specific
course to a waypoint. The database may not containall of the transitions or departures from all runways
and some GPS receivers do not contain DPs in the
database. It is necessary that helicopter procedures be
flown at 70 knots or less since helicopter departure
procedures and missed approaches use a 20:1
obstacle clearance surface (OCS), which is doublethe fixed−wing OCS, and turning areas are based on
this speed as well.
5. GPS Instrument Approach Procedures
(a)GPS overlay approaches are designated
non−precision instrument approach procedures that
pilots are authorized to fly using GPS avionics.Localizer (LOC), localizer type directional aid
(LDA), and simplified directional fac ility (SDF)
procedures are not authorized. Overlay proceduresare identified by the “name of the procedure” and “or
GPS” (e.g., VOR/DME or GPS RWY 15) in the title.
Authorized procedures must be retrievable from a
current onboard navigation databa se. The naviga-
tion database may also enhance pos ition orientation
by displaying a map containing information on
conventional NA V AID approaches. This approach
information should not be confused with a GPS
overlay approach (see the receiver operating
manual, AFM, or AFM Supplement for details on
how to identify these approaches in the navigationdatabase).
NOTE−
Overlay approaches do not adhere to the design criteria
described in Paragraph 5 −4−5m, Area Navigation (RNAV)
Instrument Approach Charts, for stand −alone GPSapproaches. Overlay approach criteria is based on the
design criteria used for ground −based NAVAID ap-
proaches.
(b)Stand−alone approach procedures spe-
cifically designed for GP S systems have replaced
many of the original overlay approaches. All
approaches that contain “GPS” in the title (e.g.,
“VOR or GPS RWY 24,” “GPS RWY 24,” or“RNA V (GPS) RWY 24”) can be flown using GPS.
GPS−equipped aircraft do not need underlying
ground−based NA V AIDs or associated aircraft
avionics to fly the approach. Monitoring the
underlying approach with ground −based NA VAIDs is
suggested when able. Existing overlay approachesmay be requested using the GPS title; for example,
the VOR or GPS RWY 24 may be requested as “GPS
RWY 24.” Some GPS procedures have a TerminalArrival Area (TAA) with an underlining RNA V
approach.
(c)For flight planning purposes,
TSO-C129() and TSO-C196() −equipped users
(GPS users) whose navigation systems have faultdetection and exclusion (FDE) capability, who
perform a preflight RAIM prediction for the
approach integrity at the airport where the RNA V(GPS) approach will be flown, and have proper
knowledge and any required training and/or
approval to conduct a GPS-based IAP, may filebased on a GPS −based IAP at either the destination
or the alternate airport, but not at both locations. At
the alternate airport, pilots may plan for:
(1)Lateral navigation (LNA V) or circling
minimum descent altitude (MDA);
(2)LNA V/vertical navigation (LNA V/
VNA V) DA, if equipped with and using approved
barometric vertical navigation (baro-VNA V) equip-ment;
(3)RNP 0.3 DA on an RNA V (RNP) IAP,
if they are specifically authorized users usingapproved baro-VNA V equipment and the pilot has
verified required navigation performance (RNP)
availability through an approved prediction program.
(d)If the above conditions cannot be met, any
required alternate airport must have an approved
instrument approach procedure other than GPS −
based that is anticipated to be operational and
available at the estimated time of arrival, and which
the aircraft is equipped to fly.
AIM 10/12/17
1−1−23 Navigation Aids(e) Procedures for Accomplishing GPS
Approaches
(1)An RNA V (GPS) procedure may be
associated with a Terminal Arrival Area (TAA). The
basic design of the RNA V procedure is the “T” design
or a modification of the “T” (See Paragraph 5-4-5d,
Terminal Arrival Area (TAA), for complete informa-
tion).
(2)Pilots cleared by ATC for an RNA V
(GPS) approach should fly the full approach from an
Initial Approach Waypoint (IAWP) or feeder fix.
Randomly joining an approach at an intermediate fixdoes not assure terrain clearance.
(3)When an approach has been loaded in
the navigation system, GPS receivers will give an
“arm” annunciation 30 NM straight line distance
from the airport/heliport reference point. Pilotsshould arm the approach mode at this time if not
already armed (some receivers arm automatically).
Without arming, the receiver will not change from
en route CDI and RAIM sensitivity of ±5 NM either
side of centerline to ±1 NM terminal sensitivity.
Where the IAWP is inside this 30 mile point, a CDIsensitivity change will occur once the approach mode
is armed and the aircraft is inside 30 NM. Where the
IAWP is beyond 30 NM from the airport/heliportreference point and the appr oach is armed, the CDI
sensitivity will not change until the aircraft is within
30 miles of the airport/heliport reference point.Feeder route obstacle clearance is predicated on the
receiver being in terminal ( ±1 NM) CDI sensitivity
and RAIM within 30 NM of the airport/heliportreference point; therefore, the receiver should always
be armed (if required) not later than the 30 NM
annunciation.
(4)The pilot must be aware of what bank
angle/turn rate the particular receiver uses to compute
turn anticipation, and whether wind and airspeed are
included in the receiver’s calculations. This informa-
tion should be in the receiver operating manual. Over
or under banking the turn onto the final approach
course may significantly delay getting on course and
may result in high descent rates to achieve the next
segment altitude.
(5)When within 2 NM of the Final
Approach Waypoint (FAWP) with the approach
mode armed, the approach mode will switch to
active, which results in RAIM and CDI changing toapproach sensitivity. Beginning 2 NM prior to the
FAWP, the full scale CDI sensitivity will smoothly
change from ±1 NM to ±0.3 NM at the FAWP. As
sensitivity changes from ±1 NM to ±0.3 NM
approaching the FAWP, with the CDI not centered,the corresponding increase in CDI displ acement
may give the impression that the aircraft is moving
further away from the intended course even though it
is on an acceptable intercept heading. Referencing the
digital track displacement information (cross track
error), if it is available in the approach mode, mayhelp the pilot remain position oriented in this
situation. Being established on the final approach
course prior to the beginning of the sensitivity change
at 2 NM will help prevent problems in interpreting the
CDI display during ramp down. Therefore, request-
ing or accepting vectors which will cause the aircraftto intercept the final approach course within 2 NM of
the FAWP is not recommended.
(6)When receiving vectors to final, most
receiver operating manuals suggest placing the
receiver in the non −sequencing mode on the FAWP
and manually setting the course. This provides an
extended final approach course in cases where the
aircraft is vectored onto the final approach course
outside of any existing segment which is aligned with
the runway. Assigned altitudes must be maintained
until established on a published segment of the
approach. Required altitudes at waypoints outside the
FAWP or stepdown fixes must be considered.
Calculating the distance to the FAWP may be
required in order to descend at the proper location.
(7)Overriding an automatically selected
sensitivity during an approach will cancel the
approach mode a nnunciation. If the approach mode
is not armed by 2 NM prior to the FAWP, the approach
mode will not become active at 2 NM prior to the
FAWP, and the equipment will flag. In theseconditions, the RAIM and CDI sensitivity will not
ramp down, and the pilot should not descend to MDA,
but fly to the MA WP and execute a missed approach.
The approach active annunciator and/or the receiver
should be checked to ensure the approach mode isactive prior to the FAWP.
(8)Do not attempt to fly an approach unless
the procedure in the onboard database is current and
identified as “GPS” on the approach chart. Thenavigation database may contain information about
non−overlay approach procedures that enhances
position orientation generally by providing a map,
AIM 10/12/17
1−1−24 Navigation Aidswhile flying these approaches using conventional
NA V AIDs. This approach information should not be
confused with a GPS overlay approach (see the
receiver operating manual, AFM, or AFM S upple-
ment for details on how to identify these proceduresin the navigation database). Flying point to point on
the approach does not assure compliance with the
published approach procedure. The proper RAIMsensitivity will not be available and the CDI
sensitivity will not automatically change to ±0.3
NM. Manually setting CDI sensitivity does notautomatically change the RAIM sensitivity on some
receivers. Some existing non −precision approach
procedures cannot be coded for use with GPS and willnot be available as overlays.
(9)Pilots should pay particular attention
to the exact operation of their GPS receivers for
performing holding patterns and in the case of
overlay approaches, operations such as procedureturns. These procedures may require manual
intervention by the pilot to stop the sequencing of
waypoints by the receiver and to resume automaticGPS navigation sequencing once the maneuver is
complete. The same waypoint may appear in the route
of flight more than once consecutively (for example,IAWP, FAWP, MAHWP on a procedure turn). Care
must be exercised to ensure that the receiver is
sequenced to the appropriate wa ypoint for the
segment of the procedure being flown, especially if
one or more fly −overs are skipped (for example,
FAWP rather than IAWP if the procedure turn is notflown). The pilot may have to sequence past one or
more fly−overs of the same waypoint in order to start
GPS automatic sequencing at the proper place in thesequence of waypoints.
(10) Incorrect inputs into the GPS receiver
are especially critical du ring approaches. In some
cases, an incorrect entry can cause the receiver to
leave the approach mode.
(11) A fix on an overlay approach identi-
fied by a DME fix will not be in the waypoint
sequence on the GPS receiver unless there is apublished name assigned to it. When a name is
assigned, the along track distance (ATD) to the
waypoint may be zero rather than the DME stated on
the approach chart. The pilot should be alert for this
on any overlay procedure where the original
approach used DME.(12) If a visual descent point (VDP) is
published, it will not be included in the sequence of
waypoints. Pilots are expected to use normal piloting
techniques for beginning the visual descent, such as
ATD.
(13) Unnamed stepdown fixes in the final
approach segment may or may not be coded in the
waypoint sequence of the aircraft’s navigation
database and must be identified using ATD.Stepdown fixes in the final approach segment of
RNA V (GPS) approaches are being named, in
addition to being identified by ATD. However, GPSavionics may or may not accommodate waypoints
between the FAF and MAP. Pilots must know the
capabilities of their GPS equipment and continue toidentify stepdown fixes using ATD when necessary.
(f) Missed Approach
(1)A GPS missed approach requires pilot
action to sequence the receiver past the MAWP to the
missed approach portion of the procedure. The pilotmust be thoroughly familiar with the activation
procedure for the particular GPS receiver installed in
the aircraft and must initiate appropriate action afterthe MAWP. Activating the missed approach prior to
the MAWP will cause CDI sensitivity to immediately
change to terminal ( ±1NM) sensitivity and the
receiver will continue to navigate to the MAWP . The
receiver will not sequence past the MAWP . T urns
should not begin prior to the MAWP. If the missed
approach is not activated, the GPS receiver will
display an extension of the inbound final approachcourse and the ATD will increase from the MAWP
until it is manually sequenced after crossing the
MAWP.
(2)Missed approach routings in which the
first track is via a course rather than direct to the next
waypoint require additional action by the pilot to set
the course. Being familiar with all of the inputs
required is especially critical during this phase of
flight.
(g) GPS NOTAMs/Aeronautical Informa-
tion
(1)GPS satellite outages are issued as
GPS NOTAMs both domestically and internation-
ally. However, the effect of an outage on the intended
operation cannot be determined unless the pilot has a
RAIM availability prediction program which allows
excluding a satellite which is predicted to be out of
service based on the NOTAM information.
AIM 10/12/17
1−1−25 Navigation Aids(2)The terms UNRELIABLE and MAY
NOT BE A V AILABLE are used in conjunction with
GPS NOTAMs. Both UNRELIABLE and MAY NOT
BE A V AILABLE are advisories to pilots indicating
the expected level of service may not be available.UNRELIABLE does not mean there is a problem
with GPS signal integrity. If GPS service is available,
pilots may continue operations. If the LNA V orLNA V/VNA V service is available, pilots may use the
displayed level of service to fly the approach. GPS
operation may be NOTAMed UNRELIABLE orMAY NOT BE AVAILABLE due to testing or
anomalies. (Pilots are encouraged to report GPS
anomalies, including degraded operation and/or lossof service, as soon as possible, reference paragraph
1−1−13.) When GPS testing NOTAMS are published
and testing is actually occurring, Air Traffic Controlwill advise pilots requesting or cleared for a GPS or
RNA V (GPS) approach that GPS may not be
available and request intentions. If pilots havereported GPS anomalies, Air Traffic Control will
request the pilot’s intentions and/or clear the pilot for
an alternate approach, if available and operational.
EXAMPLE −
The following is an example of a GPS testing NOTAM:
!GPS 06/001 ZAB NAV GPS (INCLUDING WAAS, GBAS,
AND ADS-B) MAY NOT BE AVAILABLE WITHIN A468NM RADIUS CENTERED AT 330702N1062540W(TCS 093044) FL400-UNL DECREASING IN AREAWITH A DECREASE IN ALTITUDE DEFINED AS:
425NM RADIUS AT FL250, 360NM RADIUS AT
10000FT, 354NM RADIUS AT 4000FT AGL, 327NMRADIUS AT 50FT AGL. 1406070300-1406071200.
(3)Civilian pilots may obtain GPS RAIM
availability information for non −precision approach
procedures by using a manufacturer-supplied RAIMprediction tool, or using the Service Availability
Prediction Tool (SAPT) on the FAA en route and
terminal RAIM prediction website. Pilots can alsorequest GPS RAIM aeronautical information from a
flight service station during preflight briefings. GPS
RAIM aeronautical information can be obtained fora period of 3 hours (for example, if you are scheduled
to arrive at 1215 hours, then the GPS RAIM
information is available from 1100 to 1400 hours) or
a 24−hour timeframe at a particular airport. FAA
briefers will provide RAIM information for a period
of 1 hour before to 1 hour after the ETA hour, unlessa specific timeframe is requested by the pilot. If flying
a published GPS departure, a RAIM prediction
should also be requested for the departure airport.(4)The military provides airfield specific
GPS RAIM NOTAMs for non −precision approach
procedures at military airfields. The RAIM outages
are issued as M −series NOTAMs and may be obtained
for up to 24 hours from the time of request.
(5)Receiver manufacturers and/or data-
base suppliers may supply “NOTAM” typeinformation concerning database errors. Pilots
should check these sources, when available, to ensure
that they have the most current informationconcerning their electronic database.
(h) Receiver Autonomous Integrity Moni-
toring (RAIM)
(1)RAIM outages may occur due to an
insufficient number of satellites or due to unsuitable
satellite geometry which causes the error in theposition solution to become too large. Loss of satellite
reception and RAIM warnings may occur due to
aircraft dynamics (changes in pitch or bank angle).Antenna location on the aircraft, satellite position
relative to the horizon, and aircraft attitude may af fect
reception of one or more satellites. Since the relative
positions of the satellites are constantly changing,
prior experience with the airport does not guaranteereception at all times, and RAIM availability should
always be checked.
(2)If RAIM is not available, use another
type of navigation and approach system, select
another route or destination, or delay the trip untilRAIM is predicted to be available on arrival. On
longer flights, pilots should consider rechecking the
RAIM prediction for the destination during the flight.
This may provide an early indication that an
unscheduled satellite outage has occurred since
takeoff.
(3)If a RAIM failure/status annunciation
occurs prior to the final approach waypoint
(FAWP), the approach should not be completed since
GPS no longer provides the required integrity. Thereceiver performs a RAIM prediction by 2 NM prior
to the FAWP to ensure that RAIM is available as a
condition for entering the approach mode. The pilotshould ensure the receiver has sequenced from
“Armed” to “Approach” prior to the FAWP (normally
occurs 2 NM prior). Failure to sequence may be anindication of the detection of a satellite anomaly,
failure to arm the receiver (if required), or other
problems which preclude flying the approach.
AIM 10/12/17
1−1−26 Navigation Aids(4)If the receiver does not sequence into
the approach mode or a RAIM failure/status
annunciation occurs prior to the FAWP, the pilot must
not initiate the approach or descend, but instead
proceed to the missed approach waypoint ( MAWP)via the FAWP, perform a missed approach, and
contact ATC as soon as practical. The GPS receiver
may continue to operate after a RAIM flag/statusannunciation appears, but the navigation information
should be considered advisory only. Refer to the
receiver operating manual for specific indications
and instructions associated with loss of RAIM prior
to the FAF.
(5)If the RAIM flag/status annunciation
appears after the FAWP, the pilot should initiate aclimb and execute the missed approach. The GPS
receiver may continue to operate after a RAIM
flag/status annunciation appears, but the navigationinformation should be considered advisory only.
Refer to the receiver operating manual for operating
mode information during a RAIM annunciation.
(i) Waypoints
(1)GPS receivers navigate from one
defined point to another retrieved from the aircraft’s
onboard navigational database. These points are
waypoints (5-letter pronounceable name), existingVHF intersections, DME fixes with 5 −letter
pronounceable names and 3-letter NA V AID IDs.
Each waypoint is a geographical location defined bya latitude/longitude geographic coordinate. These
5−letter waypoints, VHF intersections, 5 −letter
pronounceable DME fixes and 3 −letter NA VAID IDs
are published on various FAA aeronautical naviga-
tion products (IFR Enroute Charts, VFR Charts,
Terminal Procedures Publications, etc.).
(2)A Computer Navigation Fix (CNF) is
also a point defined by a latitude/longitude coordinate
and is required to support Performance −Based
Navigation (PBN) operations. The GPS receiver uses
CNFs in conjunction with waypoints to navigate from
point to point. However, CNFs are not recognized by
ATC. ATC does not maintain CNFs in their databaseand they do not use CNFs for any air traffic control
purpose. CNFs may or may not be charted on FAA
aeronautical navigation products, are listed in thechart legends, and are for advisory purposes only.Pilots are not to use CNFs for point to point
navigation (proceed direct), filing a flight plan, or in
aircraft/ATC communications. CNFs that do appear
on aeronautical charts allow pilots increased
situational awareness by identifying points in theaircraft database route of flight with points on the
aeronautical chart. CNFs are random five-letter
identifiers, not pronounceable like waypoints andplaced in parenthesis. Eventually, all CNFs will begin
with the letters “CF” followed by three consonants
(for example, CFWBG). This five-letter identifierwill be found next to an “x” on enroute charts and
possibly on an approach chart. On instrument
approach procedures (charts) in the terminalprocedures publication, CNFs may represent un-
named DME fixes, beginning and ending points of
DME arcs, and sensor (ground-based signal i.e.,VOR, NDB, ILS) final approach fixes on GPS
overlay approaches. These CNFs provide the GPS
with points on the procedure that allow the overlayapproach to mirror the ground-based sensor
approach. These points should only be used by the
GPS system for navigation and should not be used bypilots for any other purpose on the approach. The
CNF concept has not been adopted or recognized by
the International Civil Aviation Organization
(ICAO).
(3)GPS approaches use fly −over and
fly−by waypoints to join route segments on an
approach. Fly −by waypoints connect the two
segments by allowing the aircraft to turn prior to the
current waypoint in order to roll out on course to thenext waypoint. This is known as turn anticipation and
is compensated for in the airspace and terrain
clearances. The MAWP and the missed approachholding waypoint (MAHWP) are normally the only
two waypoints on the approach that are not fly −by
waypoints. Fly −over waypoints are used when the
aircraft must overfly the waypoint prior to starting a
turn to the new course. The symbol for a fly-over
waypoint is a circled waypoint. Some waypoints may
have dual use; for example, as a fly −by waypoint
when used as an IF for a NoPT route and as a fly-over
waypoint when the same waypoint is also used as an
IAF/IF hold-in-lieu of PT. When this occurs, the less
restrictive (fly-by) symbology will be charted.
Overlay approach charts and some early stand −alone
GPS approach charts may not reflect this convention.
AIM 10/12/17
1−1−27 Navigation Aids(4)Unnamed waypoints for each airport
will be uniquely identified in the database. Although
the identifier may be used at different airports (for
example, RW36 will be the identifier at each airport
with a runway 36), the actual point, at each airport, is
defined by a specific latitude/longitude coordinate.
(5)The runway threshold waypoint, nor-
mally the MAWP, may have a five −letter identifier
(for example, SNEEZ) or be coded as RW## (for
example, RW36, RW36L). MAWPs located at the
runway threshold are being changed to the RW##identifier, while MAWPs not located at the threshold
will have a five −letter identifier. This may cause the
approach chart to differ from the aircraft databaseuntil all changes are complete. The runway threshold
waypoint is also used as the center of the Minimum
Safe Altitude (MSA) on most GPS approaches.
(j) Position Orientation.
Pilots should pay particular attention to position
orientation while using GPS. Distance and track
information are provided to the next active
waypoint, not to a fixed navigation aid. Receiversmay sequence when the pilot is not flying along an
active route, such as when being vectored or
deviating for weather, due to the proximity to another
waypoint in the route. This can be prevented by
placing the receiver in the non-sequencing mode.
When the receiver is in the non-sequencing mode,bearing and distance are provided to the selected
waypoint and the receiver will not sequence to the
next waypoint in the route until placed back in theauto sequence mode or the pilot selects a different
waypoint. The pilot may have to compute the A TD
to stepdown fixes and other points on overlayapproaches, due to the receiver showing A TD to the
next waypoint rather than DME to the VOR or ILS
ground station.
(k) Impact of Magnetic Variation on PBN
Systems
(1)Differences may exist between PBN
systems and the charted magnetic courses on
ground−based NA VAID instrument flight procedures
(IFP), enroute charts, approach charts, and Standard
Instrument Departure/Standard Terminal Arrival
(SID/STAR) charts. These differences are due to themagnetic variance used to calculate the magneticcourse. Every leg of an instrument procedure is first
computed along a desired ground track with reference
to true north. A magnetic variation correction is then
applied to the true course in order to calculate a
magnetic course for publication. The type ofprocedure will determine what magnetic variation
value is added to the true course. A ground −based
NA V AID IFP applies the facility magnetic variationof record to the true course to get the charted magnetic
course. Magnetic courses on PBN procedures are
calculated two dif ferent ways. SID/STAR procedures
use the airport magnetic variation of record, while
IFR enroute charts use magnetic reference bearing.
PBN systems make a correction to true north byadding a magnetic variation calculated with an
algorithm based on aircraft position, or by adding the
magnetic variation coded in their navigationaldatabase. This may result in the PBN system and the
procedure designer using a different magnetic
variation, which causes the magnetic coursedisplayed by the PBN system and the magnetic course
charted on the IFP plate to be different. It is important
to understand, however, that PBN systems, (with theexception of VOR/DME RNA V equipment) navigate
by reference to true north and display magnetic
course only for pilot reference. As such, a properly
functioning PBN system, containing a current and
accurate navigational database , should fly the
correct ground track for any loaded instrument
procedure, despite differences in displayed magnetic
course that may be attributed to magnetic variation
application. Should significant differences between
the approach chart and the PBN system avionics’
application of the navigation database arise, thepublished approach chart, supplemented by NOT-
AMs, holds precedence.
(2)The course into a waypoint may not
always be 180 degrees different from the courseleaving the previous waypoint, due to the PBN
system avionics’ computation of geodesic paths,
distance between waypoints, and differences inmagnetic variation application. Variations in
distances may also occur since PBN system
distance−to−waypoint values are ATDs computed to
the next waypoint and the DME values published on
underlying procedures are slant −range distances
measured to the station. This difference increases
with aircraft altitude and proximity to the NA V AID.
AIM 10/12/17
1−1−28 Navigation Aids(l) GPS Familiarization
Pilots should practice GPS approaches in visual
meteorological conditions (VMC) until thoroughly
proficient with all aspects of their equipment
(receiver and installation) prior to attempting flightin instrument meteorological conditions (IMC).
Pilots should be proficient in the following areas:
(1)Using the receiver autonomous integ-
rity monitoring (RAIM) prediction function;
(2)Inserting a DP into the flight plan,
including setting terminal CDI sensitivity, if required,
and the conditions under which terminal RAIM is
available for departure;
(3)Programming the destination airport;
(4)Programming and flying the ap-
proaches (especially procedure turns and arcs);(5)Changing to another approach after
selecting an approach;
(6)Programming and flying “direct”
missed approaches;
(7)Programming and flying “routed”
missed approaches;
(8)Entering, flying, and exiting holding
patterns, particularly on approaches with a second
waypoint in the holding pattern;
(9)Programming and flying a “route” from
a holding pattern;
(10) Programming and flying an approach
with radar vectors to the intermediate segment;
(11) Indication of the actions required for
RAIM failure both before and after the FAWP; and
(12) Programming a radial and distance
from a VOR (often used in departure instructions).
TBL 1−1−5
GPS IFR Equipment Classes/Categories
TSO−C129
Equipment
ClassRAIMInt. Nav. Sys. to
Prov. RAIM
Equiv.Oceanic En Route TerminalNon−precision
Approach
Capable
Class A − GPS sensor and navigation capability.
A1 yes yes yes yes yes
A2 yes yes yes yes no
Class B − GPS sensor data to an integrated navigation system (i.e., FMS, multi −sensor navigation system, etc.).
B1 yes yes yes yes yes
B2 yes yes yes yes no
B3 yes yes yes yes yes
B4 yes yes yes yes no
Class C − GPS sensor data to an integrated navigation system (as in Class B) which provides enhanced guidance to an autopilot, or
flight director, to reduce flight tech. errors. Limited to 14 CFR Part 121 or equivalent criteria.
C1 yes yes yes yes yes
C2 yes yes yes yes no
C3 yes yes yes yes yes
C4 yes yes yes yes no
AIM 10/12/17
1−1−29 Navigation AidsTBL 1−1−6
GPS Approval Required/Authorized Use
Equipment
Type1Installation
Approval
RequiredOperational
Approval
RequiredIFR
En Route2IFR
Terminal2IFR
Approach3Oceanic
RemoteIn Lieu of
ADF and/or
DME3
Hand held4X5
VFR Panel Mount4 X
IFR En Route
and TerminalX X X X X
IFR Oceanic/
RemoteX X X X X X
IFR En Route,
Terminal, and
ApproachX X X X X X
NOTE−
1To determine equipment approvals and limitations, refer to the AFM, AFM supplements, or pilot guides.
2Requires verification of data for correctness if database is expired.
3Requires current database or verification that the procedure has not been amended since the expiration of the database.
4VFR and hand −held GPS systems are not authorized for IFR navigation, instrument approaches, or as a primary instrument
flight reference. During IFR operations they may be considered only an aid to situational awareness.
5Hand−held receivers require no approval. However, any aircraft modification to support the hand −held receiver;
i.e., installation of an external antenna or a permanent mounting bracket, does require approval.
1−1−18. Wide Area Augmentation System
(WAAS)
a. General
1.The FAA developed the WAAS to improve
the accuracy, integrity and availability of GPS
signals. WAAS will allow GPS to be used, as theaviation navigation system, from takeoff through
approach when it is complete. WAAS is a critical
component of the FAA’s strategic objective for aseamless satellite navigation system for civil
aviation, improving capacity and safety.
2.The International Civil Aviation Organiza-
tion (ICAO) has defined Standards and
Recommended Practices (SARPs) for satellite −based
augmentation systems (SBAS) such as WAAS.Japan, India, and Europe are building similar
systems: EGNOS, the European Geostationary
Navigation Overlay System; India’s GPS andGeo-Augmented Navigation (GAGAN) system; and
Japan’s Multi-functional Transport Satellite (MT-
SAT)-based Satellite Augmentation System(MSAS). The merging of these systems will create an
expansive navigation capability similar to GPS, but
with greater accuracy, availability, and integrity.3.Unlike traditional ground −based navigation
aids, W AAS will cover a more extensive service area.
Precisely surveyed wide −area reference stations
(WRS) are linked to form the U.S. WAAS network.
Signals from the GPS satellites are monitored bythese WRSs to determine satellite clock and
ephemeris corrections and to model the propagation
effects of the ionosphere. Each station in the network
relays the data to a wide−area master station (WMS)
where the correction information is computed. A
correction message is prepared and uplinked to ageostationary earth orbit satellite (GEO) via a GEO
uplink subsystem (GUS) which is located at the
ground earth station (GES). The message is thenbroadcast on the same frequency as GPS (L1,
1575.42 MHz) to WAAS receivers within the
broadcast coverage area of the WAAS GEO.
4.In addition to providing the correction signal,
the W AAS GEO provides an additional pseudorangemeasurement to the aircraft receiver, improving the
availability of GPS by providing, in effect, an
additional GPS satellite in view. The integrity of GPS
is improved through real −time monitoring, and the
accuracy is improved by providing differential
corrections to reduce errors. The performance
AIM 10/12/17
1−1−30 Navigation Aidsimprovement is sufficient to enable approach
procedures with GPS/WAAS glide paths (vertical
guidance).
5.The FAA has completed installation of 3
GEO satellite links, 38 WRSs, 3 WMSs, 6 GES, and
the required terrestrial communications to support
the WAAS network including 2 operational controlcenters. Prior to the commissioning of the WAAS for
public use, the FAA conducted a series of test and
validation activities. Future dual frequency opera-tions are planned.
6.GNSS navigation, including GPS and
WAAS, is referenced to the WGS −84 coordinate
system. It should only be used where the A eronautical
Information Publications (including electronic dataand aeronautical charts) conform to WGS −84 or
equivalent. Other countries’ civil aviation authorities
may impose additional limitations on the use of theirSBAS systems.
b. Instrument Approach Capabilities
1.A class of approach procedures which
provide vertical guidance, but which do not meet the
ICAO Annex 10 requirements for precision ap-
proaches has been developed to support satellite
navigation use for aviation applications worldwide.
These procedures are not precision and are referred to
as Approach with Vertical Guidance (APV), aredefined in ICAO Annex 6, and include approaches
such as the LNA V/VNA V and localizer performance
with vertical guidance (LPV). These approachesprovide vertical guidance, but do not meet the more
stringent standards of a precision approach. Properly
certified WAAS receivers will be able to fly to LPVminima and LNA V/VNA V minima, using a WAAS
electronic glide path, which eliminates the errors that
can be introduced by using Barometric altimetry.
2.LPV minima takes advantage of the high
accuracy guidance and increased integrity providedby WAAS. This WAAS generated angular guidance
allows the use of the same TERPS approach criteria
used for ILS approaches. LPV minima may have adecision altitude as low as 200 feet height above
touchdown with visibility minimums as low as
1/2
mile, when the terrain and airport infrastructure
support the lowest minima. LPV minima is published
on the RNA V (GPS) approach charts (see Paragraph
5−4−5, Instrument Approach Procedure Charts).3.A different WAAS-based line of minima,
called Localizer Performance (LP) is being added in
locations where the terrain or obstructions do not
allow publication of vertically guided LPV minima.
LP takes advantage of the angular lateral guidanceand smaller position errors provided by WAAS to
provide a lateral only procedure similar to an ILS
Localizer. LP procedures may provide lower minima
than a LNA V procedure due to the narrower obstacle
clearance surface.
NOTE−
WAAS receivers certified prior to TSO −C145b and
TSO−C146b, even if they have LPV capability, do not
contain LP capability unless the receiver has been
upgraded. Receivers capable of flying LP pr ocedures must
contain a statement in the Aircraft Flight Manual (AFM),AFM Supplement, or Approved Supplemental FlightManual stating that the receiver has LP capability, as well
as the capability for the other WAAS and GPS approach
procedure types.
4.WAAS provides a level of service that
supports all phases of flight, including RNA V (GPS)
approaches to LNA V , LP, LNA V/VNA V , and LPV
lines of minima, within system coverage. Somelocations close to the edge of the coverage may have
a lower availability of vertical guidance.
c. General Requirements
1.WAAS avionics must be certified in
accordance with Technical Standard Order (TSO)
TSO−C145(), Airborne Navigation Sensors Using
the (GPS) Augmented by the Wide Area Augmenta-
tion System (WAAS); or TSO −C146(), Stand −Alone
Airborne Navigation Equipment Using the GlobalPositioning System (GPS) Augmented by the Wide
Area Augmentation System (WAAS), and installed in
accordance with AC 20 −138, Airworthiness Ap-
proval of Positioning and Navigation Systems.
2.GPS/WAAS operation must be conducted in
accordance with the FAA −approved aircraft flight
manual (AFM) and flight manual supplements. Flight
manual supplements will state the level of approach
procedure that the receiver supports. IFR approved
WAAS receivers support all GPS only operations as
long as lateral capability at the appropriate level is
functional. WAAS monitors both GPS and WAASsatellites and provides integrity.
3.GPS/WAAS equipment is inherently capable
of supporting oceanic and remote operations if the
operator obtains a fault detection and exclusion
(FDE) prediction program.
AIM 10/12/17
1−1−31 Navigation Aids4.Air carrier and commercial operators must
meet the appropriate provisions of their approved
operations specifications.
5.Prior to GPS/WAAS IFR operation, the pilot
must review appropriate Notices to Airmen (NOT-
AMs) and aeronautical information. This
information is available on request from a FlightService Station. The FAA will provide NOTAMs to
advise pilots of the status of the WAAS and level of
service available.
(a)The term MAY NOT BE A VBL is used in
conjunction with W AAS NOTAMs and indicates that
due to ionospheric conditions, lateral guidance may
still be available when vertical guidance isunavailable. Under certain conditions, both lateral
and vertical guidance may be unavailable. This
NOTAM language is an advisory to pilots indicatingthe expected level of WAAS service (LNA V/VNA V ,
LPV , LP) may not be available.
EXAMPLE −
!FDC FDC NAV WAAS VNAV/LPV/LP MINIMA MAY
NOT BE AVBL 1306111330-1306141930EST
or !FDC FDC NAV WAAS VNAV/LPV MINIMA NOT AVBL,WAAS LP MINIMA MAY NOT BE AVBL1306021200-1306031200EST
WAAS MAY NOT BE A VBL NOTAMs are
predictive in nature and published for flight planning
purposes. Upon commencing an approach at
locations NOTAMed WAAS MAY NOT BE A VBL,if the W AAS avionics indicate LNA V/VNA V or LPV
service is available, then vertical guidance may be
used to complete the approach using the displayedlevel of service. Should an outage occur during the
approach, reversion to LNA V minima or an alternate
instrument approach procedure may be required.When GPS testing NOTAMS are published and
testing is actually occurring, Air Traffic Control will
advise pilots requesting or cleared for a GPS or
RNA V (GPS) approach that GPS may not be
available and request intentions. If pilots havereported GPS anomalies, Air Traffic Control will
request the pilot’s intentions and/or clear the pilot for
an alternate approach, if available and operational.
(b)WAAS area-wide NOTAMs are origin-
ated when WAAS assets are out of service and impact
the service area. Area −wide WAAS NOT A V AIL-
ABLE (A VBL) NOTAMs indicate loss or
malfunction of the WAAS system. In flight, AirTraffic Control will advise pilots requesting a GPS or
RNA V (GPS) approach of WAAS NOT A VBL
NOTAMs if not contained in the ATIS broadcast.
EXAMPLE −
For unscheduled loss of signal or service, an example
NOTAM is: !FDC FDC NAV WAAS NOT AVBL
1311160600 − 1311191200EST.
For scheduled loss of signal or service, an exampleNOTAM is: !FDC FDC NAV WAAS NOT AVBL1312041015- 1312082000EST.
(c)Site−specific WAAS MAY NOT BE
A VBL NOTAMs indicate an expected level of
service; for example, LNA V/VNA V , LP , or LPV may
not be available. Pilots must request site −specific
WAAS NOTAMs during flight planning. In flight,
Air Traffic Control will not advise pilots of WAASMAY NOT BE A VBL NOTAMs.
NOTE−
Though currently unavailable, the F AA is updating itsprediction tool software to provide this site-service in the
future.
(d)Most of North America has redundant
coverage by two or more geostationary satellites. One
exception is the northern slope of Alaska. If there is
a problem with the satellite providing coverage to this
area, a NOTAM similar to the following example will
be issued:
EXAMPLE −
!FDC 4/3406 (P AZA A0173/14) ZAN NAV WAAS SIGNAL
MAY NOT BE AVBL NORTH OF LINE FROM
7000N150000W TO 6400N16400W. RMK WAAS USERS
SHOULD CONFIRM RAIM AVAILABILITY FOR IFROPERATIONS IN THIS AREA. T-ROUTES IN THISSECTOR NOT AVBL. ANY REQUIRED ALTERNATEAIRPORT IN THIS AREA MUST HAVE AN APPROVED
INSTRUMENT APPROACH PROCEDURE OTHER
THAN GPS THAT IS ANTICIP ATED TO BE OPERA-TIONAL AND AVAILABLE AT THE ESTIMATED TIMEOF ARRIVAL AND WHICH THE AIRCRAFT ISEQUIPPED TO FLY. 1406030812-1406050812EST .
6.When GPS −testing NOTAMS are published
and testing is actually occurring, Air Traffic Control
will advise pilots requesting or cleared for a GPS or
RNA V (GPS) approach that GPS may not be
available and request intentions. If pilots havereported GPS anomalies, Air Traffic Control will
request the pilot’s intentions and/or clear the pilot for
an alternate approach, if available and operational.
EXAMPLE −
Here is an example of a GPS testing NOTAM: !GPS 06/001 ZAB NAV GPS (INCLUDING WAAS, GBAS,
AIM 10/12/17
1−1−32 Navigation AidsAND ADS-B) MAY NOT BE AVAILABLE WITHIN A
468NM RADIUS CENTERED AT 330702N1062540W(TCS 093044) FL400-UNL DECREASING IN AREAWITH A DECREASE IN ALTITUDE DEFINED AS:
425NM RADIUS AT FL250, 360NM RADIUS AT
10000FT, 354NM RADIUS AT 4000FT AGL, 327NMRADIUS AT 50FT AGL. 1406070300-1406071200.
7.When the approach chart is annotated with
the
symbol, site −specific WAAS MAY NOT BE
A VBL NOTAMs or Air Traffic advisories are not
provided for outages in WAAS LNA V/VNA V and
LPV vertical service. Vertical outages may occur
daily at these locations due to being close to the edge
of WAAS system coverage. Use LNA V or circling
minima for flight planning at these locations, whether
as a destination or alternate. For flight operations atthese locations, when the WAAS avionics indicate
that LNA V/VNA V or LPV service is available, then
the vertical guidance may be used to complete theapproach using the displayed level of service. Should
an outage occur during the procedure, reversion to
LNA V minima may be required.
NOTE−
Area−wide WAAS NOT AVBL NOTAMs apply to all
airports in the WAAS NOT AVBL area designated in theNOTAM, including approaches at airports where an
approach chart is annotated with the
symbol.
8.GPS/WAAS was developed to be used within
GEO coverage over North America without the need
for other radio navigation equipment appropriate to
the route of flight to be flown. Outside the WAAScoverage or in the event of a WAAS failure,
GPS/WAAS equipment reverts to GPS −only opera-
tion and satisfies the requirements for basic GPSequipment. (See paragraph 1 −1−17 for these
requirements).
9.Unlike TSO −C129 avionics, which were
certified as a supplement to other means of
navigation, WAAS avionics are evaluated without
reliance on other navigation systems. As such,installation of WAAS avionics does not require the
aircraft to have other equipment appropriate to the
route to be flown. (See paragraph 1 −1−17 d for more
information on equipment requirements.)
(a)Pilots with WAAS receivers may flight
plan to use any instrument approach procedureauthorized for use with their WAAS avionics as
the planned approach at a required alternate, with
the following restrictions. When using WAAS atan alternate airport, flight planning must be based
on flying the RNA V (GPS) LNA V or circling minima
line, or minima on a GPS approach procedure, or
conventional approach procedure with “or GPS” in
the title. Code of Federal Regulation (CFR) Part 91non−precision weather requirements must be used for
planning. Upon arrival at an alternate, when the
WAAS navigation system indicates that LNA V/VNA V or LPV service is available, then vertical
guidance may be used to complete the approach using
the displayed level of service. The FAA has begun
removing the
NA (Alternate Minimums Not
Authorized) symbol from select RNA V (GPS) andGPS approach procedures so they may be used by
approach approved WAAS receivers at alternate
airports. Some approach procedures will still require
the
NA for other reasons, such as no weather
reporting, so it cannot be removed from allprocedures. Since every procedure must be individu-
ally evaluated, removal of the
NA from RNA V
(GPS) and GPS procedures will take some time.
NOTE−
Properly trained and approved, as required, TSO-C145()
and TSO-C146() equipped users (WAAS users) with andusing approved baro-VNAV equipment may plan forLNAV/VNAV DA at an alternate airport. Specificallyauthorized WAAS users with and using approved
baro-VNAV equipment may also plan for RNP 0.3 DA at the
alternate airport as long as the pilot has verified RNPavailability through an approved prediction program.
d. Flying Procedures with WAAS
1.WAAS receivers support all basic GPS
approach functions and provide additional capabilit-
ies. One of the major improvements is the ability to
generate glide path guidance, independent of ground
equipment or barometric aiding. This eliminates
several problems such as hot and cold temperature
effects, incorrect altimeter setting, or lack of a localaltimeter source. It also allows approach procedures
to be built without the cost of installing ground
stations at each airport or runway. Some approachcertified receivers may only generate a glide path
with performance similar to Baro −VNA V and are
only approved to fly the LNA V/VNA V line of minima
on the RNA V (GPS) approach charts. Receivers with
additional capability (including faster update rates
and smaller integrity limits) are approved to fly theLPV line of minima. The lateral integrity changes
dramatically from the 0.3 NM (556 meter) limit for
GPS, LNA V , and LNA V/VNA V approach mode, to
AIM 10/12/17
1−1−33 Navigation Aids40 meters for LPV . It also provides vertical integrity
monitoring, which bounds the vertical error to 50
meters for LNA V/VNA V and LPVs with minima of
250’ or above, and bounds the vertical error to 35
meters for LPVs with minima below 250’.
2.When an approach procedure is selected and
active, the receiver will notify the pilot of the most
accurate level of service supported by the combina-
tion of the WAAS signal, the receiver, and the
selected approach, using the naming conventions on
the minima lines of the selected approach procedure.For example, if an approach is published with LPV
minima and the receiver is only certified for
LNA V/VNA V , the equipment would indicate“LNA V/VNA V available,” even though the WAAS
signal would support LPV . If flying an existing
LNA V/VNA V procedure with no LPV minima, thereceiver will notify the pilot “LNA V/VNA V
available,” even if the receiver is certified for LPV
and the signal supports LPV . If the signal does notsupport vertical guidance on procedures with LPV
and/or LNA V/VNA V minima, the receiver annunci-
ation will read “LNA V available.” On lateral onlyprocedures with LP and LNA V minima the receiver
will indicate “LP available” or “LNA V available”
based on the level of lateral service available. Oncethe level of service notification has been given, the
receiver will operate in this mode for the duration of
the approach procedure, unless that level of servicebecomes unavailable. The receiver cannot change
back to a more accurate level of service until the next
time an approach is activated.
NOTE−
Receivers do not “fail down” to lower levels of serviceonce the approach has been activated. If only the
vertical off flag appears, the pilot may elect to use the
LNAV minima if the rules under which the flight isoperating allow changing the type of approach being flown
after commencing the procedure. If the lateral integritylimit is exceeded on an LP approach, a missed approach
will be necessary since there is no way to reset the lateral
alarm limit while the approach is active.
3.Another additional feature of WAAS receiv-
ers is the ability to exclude a bad GPS signal andcontinue operating normally. This is normally
accomplished by the WAAS correction information.
Outside WAAS coverage or when WAAS is notavailable, it is accomplished through a receiver
algorithm called FDE. In most cases this operation
will be invisible to the pilot since the receiver willcontinue to operate with other available satellites
after excluding the “bad” signal. This capability
increases the reliability of navigation.
4.Both lateral and vertical scaling for the
LNA V/VNA V and LPV approach procedures are
different than the linear scaling of basic GPS. When
the complete published procedure is flown, ±1 NM
linear scaling is provided until two (2) NM prior to the
FAF, where the sensitivity increases to be similar tothe angular scaling of an ILS. There are two differ-
ences in the W AAS scaling and ILS: 1) on long final
approach segments, the initial scaling will be
±0.3 NM to achieve equivalent performance to GPS
(and better than ILS, which is less sensitive far fromthe runway); 2) close to the runway threshold, the
scaling changes to linear instead of continuing to
become more sensitive. The width of the finalapproach course is tailored so that the total width is
usually 700 feet at the runway threshold. Since the
origin point of the lateral splay for the angular portion
of the final is not fixed due to antenna placement like
localizer, the splay angle can remain fixed, making a
consistent width of final for aircraft being vectoredonto the final approach course on different length
runways. When the complete published procedure is
not flown, and instead the aircraft needs to capture theextended final approach course similar to ILS, the
vector to final (VTF) mode is used. Under VTF, the
scaling is linear at ±1 NM until the point where the
ILS angular splay reaches a width of ±1 NM
regardless of the distance from the FAWP.
5.The W AAS scaling is also different than GPS
TSO−C129() in the initial portion of the missed
approach. Two differences occur here. First, the
scaling abruptly changes from the approach scaling to
the missed approach scaling, at approximately the
departure end of the runway or when the pilot selects
missed approach guidance rather than ramping asGPS does. Second, when the first leg of the missed
approach is a Track to Fix (TF) leg aligned within 3
degrees of the inbound course, the receiver will
change to 0.3 NM linear sensitivity until the turn
initiation point for the first waypoint in the missedapproach procedure, at which time it will abruptly
change to terminal ( ±1 NM) sensitivity. This allows
the elimination of close in obstacles in the early partof the missed approach that may otherwise cause the
DA to be raised.
6.There are two ways to select the final
approach segment of an instrument approach. Most
AIM 10/12/17
1−1−34 Navigation Aidsreceivers use menus where the pilot selects the
airport, the runway, the specific approach procedure
and finally the IAF, there is also a channel number
selection method. The pilot enters a unique 5 −digit
number provided on the approach chart, and thereceiver recalls the matching final approach segment
from the aircraft database. A list of information
including the available IAFs is displayed and the pilot
selects the appropriate IAF. The pilot should confirm
that the correct final approach segment was loaded by
cross checking the Approach ID, which is alsoprovided on the approach chart.
7.The Along −Track Distance (ATD) during the
final approach segment of an LNA V procedure (with
a minimum descent altitude) will be to the MAWP. OnLNA V/VNA V and LPV approaches to a decision
altitude, there is no missed approach waypoint so the
along−track distance is displayed to a point normally
located at the runway threshold. In most cases, the
MAWP for the LNA V approach is located on the
runway threshold at the centerline, so these distances
will be the same. This distance will always vary
slightly from any ILS DME that may be present, since
the ILS DME is located further down the runway.Initiation of the missed approach on the LNA V/
VNAV and LPV approaches is still based on reaching
the decision altitude without any of the items listed in
14 CFR Section 91.175 being visible, and must not be
delayed while waiting for the ATD to reach zero. The
WAAS receiver, unlike a GPS receiver, will
automatically sequence past the MAWP if the missed
approach procedure has been designed for RNA V .The pilot may also select missed approach prior to the
MAWP; however, navigation will continue to the
MAWP prior to waypoint sequencing taking place.
1−1−19. Ground Based Augmentation
System (GBAS) Landing System (GLS)
a. General
1.The GLS provides precision navigation
guidance for exact alignment and descent of aircraft
on approach to a runway. It provides differential
augmentation to the Global Navigation SatelliteSystem (GNSS).
NOTE−
GBAS is the ICAO term for Local Area AugmentationSystem (LAAS).2.LAAS was developed as an “ILS look −alike”
system from the pilot perspective. LAAS is based on
GPS signals augmented by ground equipment and has
been developed to provide GLS precision approaches
similar to ILS at airfields.
3.GLS provides guidance similar to ILS
approaches for the final approach segment; portionsof the GLS approach prior to and after the final
approach segment will be based on Area Navigation
(RNA V) or Required Navigation Performance(RNP).
4.The equipment consists of a GBAS Ground
Facility (GGF), four reference stations, a VHF Data
Broadcast (VDB) uplink antenna, and an aircraft
GBAS receiver.
b. Procedure
1.Pilots will select the five digit GBAS channel
number of the associated approach within the FlightManagement System (FMS) menu or manually select
the five digits (system dependent). Selection of the
GBAS channel number also tunes the VDB.
2.Following procedure selection, confirmation
that the correct LAAS procedure is loaded can beaccomplished by cross checking the charted
Reference Path Indicator (RPI) or approach ID with
the cockpit displayed RPI or audio identification ofthe RPI with Morse Code (for some systems).
3.The pilot will fly the GLS approach using the
same techniques as an ILS, once selected and
identified.
1−1−20. Precision Approach Systems other
than ILS and GLS
a. General
Approval and use of precision approach systems
other than ILS and GLS require the issuance ofspecial instrument approach procedures.
b. Special Instrument Approach Procedure
1.Special instrument approach procedures
must be issued to the aircraft operator if pilot training,
aircraft equipment, and/or aircraft performance is
different than published procedures. Special instru-
ment approach procedures are not distributed forgeneral public use. These procedures are issued to an
aircraft operator when the conditions for operations
approval are satisfied.
AIM 10/12/17
1−1−35 Navigation Aids2.General aviation operators requesting ap-
proval for special procedures should contact the local
Flight Standards District Office to obtain a letter of
authorization. Air carrier operators requesting
approval for use of special procedures should contact
their Certificate Holding District Office for authoriz-
ation through their Operations Specification.
c. Transponder Landing System (TLS)
1.The TLS is designed to provide approach
guidance utilizing existing airborne ILS localizer,
glide slope, and transponder equipment.
2.Ground equipment consists of a transponder
interrogator, sensor arrays to detect lateral and
vertical position, and ILS frequency transmitters. The
TLS detects the aircraft’s position by interrogating its
transponder. It then broadcasts ILS frequency signals
to guide the aircraft along the desired approach path.
3.TLS instrument approach procedures are
designated Special Instrument Approach Procedures.
Special aircrew training is required. TLS ground
equipment provides approach guidance for only one
aircraft at a time. Even though the TLS signal is
received using the ILS receiver, no fixed course or
glidepath is generated. The concept of operation isvery similar to an air traf fic controller providing radar
vectors, and just as with radar vectors, the guidance
is valid only for the intended aircraft. The TLSground equipment tracks one aircraft, based on its
transponder code, and provides correction signals tocourse and glidepath based on the position of the
tracked aircraft. Flying the TLS corrections com-
puted for another aircraft will not provide guidance
relative to the approach; therefore, aircrews must not
use the TLS signal for navigation unless they havereceived approach clearance and completed the
required coordination with the TLS ground equip-
ment operator. Navigation fixes based onconventional NA V AIDs or GPS are provided in the
special instrument approach procedure to allow
aircrews to verify the TLS guidance.
d. Special Categ ory I Differential GPS (SCAT −
I DGPS)
1.The SCAT −I DGPS is designed to provide
approach guidance by broadcasting differential
correction to GPS.
2.SCAT−I DGPS procedures require aircraft
equipment and pilot training.
3.Ground equipment consists of GPS receivers
and a VHF digital radio transmitter. The SCAT −I
DGPS detects the position of GPS satellites relativeto GPS receiver equipment and broadcasts differen-
tial corrections over the VHF digital radio.
4.Category I Ground Based Augmentation
System (GBAS) will displace SCAT −I DGPS as the
public use service.
REFERENCE −
AIM, Paragraph 5 −4−7 f, Instrument Approach Procedures
AIM 10/12/17
1−2−1 Performance −Based Navigation (PBN) and Area Navigation (RNA V)Section 2. Performance −Based Navigation (PBN) and
Area Navigation (RNAV)
1−2−1. General
a. Introduction to PBN. As air travel has
evolved, methods of navigation have improved to
give operators more flexibility. Under the umbrella of
area navigation, there are legacy and performance −
based navigation (PBN) methods, see FIG 1−2−1.
The legacy methods include operations incorporating
systems approved under AC 90-45, Approval of Area
Navigation Systems for Use in the U.S. National
Airspace System, which allows two-dimensionalarea navigation (2D RNA V) within the U.S. National
Airspace System (NAS). AC 90-45 describes 2D
RNA V in terms of both VOR/DME dependentsystems and self-contained systems such as Inertial
Navigation Systems (INS). Many operators have
upgraded their systems to obtain the benefits of PBN.
Within PBN there are two main categories of
navigation methods: area navigation (RNA V) and
required navigation performance (RNP). For anaircraft to meet the requirements of RNA V , a
specified RNA V accuracy must be met 95 percent of
the flight time. RNP is an RNA V system that includes
onboard performance monitoring and alerting
capability (for example, Receiver Autonomous
Integrity Monitoring (RAIM)). PBN also introduces
the concept of navigation specifications (Nav Specs)
which are a set of aircraft and aircrew requirementsneeded to support a navigation application within a
defined airspace concept. For both RNP and RNA V
designations, the numerical designation refers to thelateral navigation accuracy in nautical miles which is
expected to be achieved at least 95 percent of the
flight time by the population of aircraft operatingwithin the airspace, route, or procedure. This
information is introduced in International Civil
Aviation Organization’s (ICAO) Doc 9613, Perform-
ance-based Navigation (PBN) Manual (Fourth
Edition, 2013) and the FAA AC 90-105A, Approval
Guidance for RNP Operations and BarometricVertical Navigation in the U.S. National Airspace
System and in Remote and Oceanic Airspace
(expected publication date in late 2014) furtherdevelops this story.FIG 1−2−1
b. Area Navigation (RNA V)
1. General. RNA V is a method of navigation
that permits aircraft operation on any desired flight
path within the coverage of ground − or space−based
navigation aids or within the limits of the capabilityof self−contained aids, or a combination of these. In
the future, there will be an increased dependence on
the use of RNA V in lieu of routes defined byground−based navigation aids. RNA V routes and
terminal procedures, including departure procedures
(DPs) and standard terminal arrivals (STARs), are
designed with RNA V systems in mind. There are
several potential advantages of RNA V routes andprocedures:
(a)Time and fuel savings;
(b)Reduced dependence on radar vectoring,
altitude, and speed assignments allowing a reduction
in required ATC radio transmissions; and
(c)More efficient use of airspace.
In addition to information found in this manual,
guidance for domestic RNA V DPs, STARs, and
routes may also be found in AC 90 −100, U.S.
Terminal and En Route Area Navigation (RNA V)
Operations.
2. RNAV Operations. RNA V procedures, such
as DPs and ST ARs, demand strict pilot awareness and
maintenance of the procedure centerline. Pilots
AIM 10/12/17
1−2−2 Performance −Based Navigation (PBN) and Area Navigation (RNA V)should possess a working knowledge of their aircraft
navigation system to ensure RNA V procedures are
flown in an appropriate manner. In addition, pilots
should have an understanding of the various
waypoint and leg types used in RNA V procedures;these are discussed in more detail below.
(a) Waypoints. A waypoint is a predeter-
mined geographical position that is defined in terms
of latitude/longitude coordinates. Waypoints may bea simple named point in space or associated with
existing navaids, intersections, or fixes. A waypoint
is most often used to indicate a change in direction,speed, or altitude along the desired path. RNA V
procedures make use of both fly −over and fly −by
waypoints.
(1) Fly−by waypoints. Fly−by waypoints
are used when an aircraft should begin a turn to the
next course prior to reaching the waypoint separating
the two route segments. This is known as turnanticipation.
(2) Fly−over waypoints. Fly−over way-
points are used when the aircraft must fly over the
point prior to starting a turn.
NOTE−
FIG 1−2−2 illustrates several differ ences between a fly −by
and a fly−over waypoint.
FIG 1−2−2
Fly−by and Fly −over W aypoints
(b) RNA V Leg Types. A leg type describes
the desired path proceeding, following, or between
waypoints on an RNA V procedure. Leg types are
identified by a two −letter code that describes the path
(e.g., heading, course, track, etc.) and the termination
point (e.g., the path terminates at an altitude, distance,
fix, etc.). Leg types used for procedure design are
included in the aircraft navigation database, but notnormally provided on the procedure chart. The
narrative depiction of the RNA V chart describes how
a procedure is flown. The “path and terminatorconcept” defines that every leg of a procedure has a
termination point and some kind of path into that
termination point. Some of the available leg types are
described below.
(1) Track to Fix. A Track to Fix (TF) leg
is intercepted and acquired as the flight track to the
following waypoint. Track to a Fix legs aresometimes called point −to−point legs for this reason.
Narrative: “direct ALPHA, then on course to
BRAVO WP .” See FIG 1−2−3.
(2) Direct to Fix. A Direct to Fix (DF) leg
is a path described by an aircraft’s track from an initialarea direct to the next waypoint. Narrative: “turn
right direct BRAVO WP .” See FIG 1−2−4.
FIG 1−2−3
Track to Fix Leg Type
AIM 10/12/17
1−2−3 Performance −Based Navigation (PBN) and Area Navigation (RNA V)FIG 1−2−4
Direct to Fix Leg Type
(3) Course to Fix. A Course to Fix (CF)
leg is a path that terminates at a fix with a specifiedcourse at that fix. Narrative: “on course 150 to
ALPHA WP .” See FIG 1−2−5.
FIG 1−2−5
Course to Fix Leg Type
(4) Radius to Fix. A Radius to Fix (RF)
leg is defined as a constant radius circular path around
a defined turn center that terminates at a fix. See
FIG 1−2−6.FIG 1−2−6
Radius to Fix Leg Type
(5) Heading. A Heading leg may be
defined as, but not limited to, a Heading to Altitude
(V A), Heading to DME range (VD), and Heading to
Manual Termination, i.e., Vector (VM). Narra-
tive: “climb heading 350 to 1500”, “heading 265, at
9 DME west of PXR VORTAC, right turn heading
360”, “fly heading 090, expect radar vectors toDRYHT INT.”
(c) Navigation Issues. Pilots should be
aware of their navigation system inputs, alerts, andannunciations in order to make better −informed
decisions. In addition, the availability and suitability
of particular sensors/systems should be considered.
(1) GPS/WAAS. Operators using TSO −
C129(), TSO −C196(), TSO −C145() or TSO −C146()
systems should ensure departure and arrival airports
are entered to ensure proper RAIM availability and
CDI sensitivity.
(2) DME/DME. Operators should be
aware that DME/DME position updating is depen-
dent on navigation system logic and DME facilityproximity, availability, geometry, and signal mask-
ing.
(3) VOR/DME. Unique VOR character-
istics may result in less accurate values from
VOR/DME position updating than from GPS orDME/DME position updating.
(4) Inertial Navigation. Inertial reference
units and inertial navigation systems are oftencoupled with other types of navigation inputs,
e.g., DME/DME or GPS, to improve overall
navigation system performance.
AIM 10/12/17
1−2−4 Performance −Based Navigation (PBN) and Area Navigation (RNA V)NOTE−
Specific inertial position updating requirements mayapply.
(d) Flight Management System
(FMS). An FMS is an integrated suite of sensors,
receivers, and computers, coupled with a navigation
database. These systems generally provide perfor-
mance and RNA V guidance to displays and automatic
flight control systems.
Inputs can be accepted from multiple sources such as
GPS, DME, VOR, LOC and IRU. These inputs may
be applied to a navigation solution one at a time or in
combination. Some FMSs provide for the detectionand isolation of faulty navigation information.
When appropriate navigation signals are available,
FMSs will normally rely on GPS and/or DME/DME(that is, the use of distance information from two or
more DME stations) for position updates. Other
inputs may also be incorporated based on FMS
system architecture and navigation source geometry.
NOTE−
DME/DME inputs coupled with one or more IRU(s) areoften abbreviated as DME/DME/IRU or D/D/I.
(e) RNA V Navigation Specifications (Nav
Specs)
Nav Specs are a set of aircraft and aircrew
requirements needed to support a navigationapplication within a defined airspace concept. For
both RNP and RNA V designations, the numerical
designation refers to the lateral navigation accuracyin nautical miles which is expected to be achieved at
least 95 percent of the flight time by the population of
aircraft operating within the airspace, route, orprocedure. (See FIG 1−2−1.)
(1) RNA V 1. Typically RNA V 1 is used for
DPs and STARs and appears on the charts. Aircraft
must maintain a total system error of not more than
1 NM for 95 percent of the total flight time.
(2) RNA V 2. Typically RNA V 2 is used for
en route operations unless otherwise specified.
T-routes and Q-routes are examples of this Nav Spec.
Aircraft must maintain a total system error of not
more than 2 NM for 95 percent of the total flight time.
(3) RNA V 10. Typically RNA V 10 is used
in oceanic operations. See paragraph 4 −7−1 for
specifics and explanation of the relationship between
RNP 10 and RNA V 10 terminology.1−2−2. Required Navigation Performance
(RNP)
a. General. RNP is RNA V with onboard naviga-
tion monitoring and alerting. RNP is also a statement
of navigation performance necessary for operationwithin a defined airspace. A critical component of
RNP is the ability of the aircraft navigation system to
monitor its achieved navigation performance, and to
identify for the pilot whether the operational
requirement is, or is not, being met during an
operation . This onboard performance monitoring
and alerting capability therefore allows a lessened
reliance on air traffic control intervention (via radar
monitoring, automatic dependent surveillance(ADS), multilateration, communications), and/or
route separation to achieve the overall safety of the
operation. RNP capability of the aircraft is a majorcomponent in determining the separation criteria to
ensure that the overall containment of the operation
is met.
The RNP capability of an aircraft will vary depending
upon the aircraft equipment and the navigation
infrastructure. For example, an aircraft may be
equipped and certified for RNP 1.0, but may not becapable of RNP 1.0 operations due to limited
NA V AID coverage.
b. RNP Operations.
1. Lateral Accuracy Values. Lateral Accuracy
values are applicable to a selected airspace, route, orprocedure. The lateral accuracy value is a value
typically expressed as a distance in nautical miles
from the intended centerline of a procedure, route, or
path. RNP applications also account for potential
errors at some multiple of lateral accuracy value (for
example, twice the RNP lateral accuracy values).
(a) Nav Specs and Standard Lateral
Accuracy Values. U.S. standard values supporting
typical RNP airspace are as specified below. Other
lateral accuracy values as identified by ICAO, otherstates, and the FAA may also be used. (See
FIG 1−2−1.)
(1) RNP Approach (APCH). RNP APCH
procedures are titled RNA V (GPS) and offer severallines of minima to accommodate varying levels of
aircraft equipage: either lateral navigation (LNA V),
LNA V/vertical navigation (LNA V/VNA V), and
Localizer Performance with Vertical Guidance
(LPV), or LNA V , and Localizer Performance (LP).
GPS or WAAS can provide the lateral information to
AIM 10/12/17
1−2−5 Performance −Based Navigation (PBN) and Area Navigation (RNA V)support LNA V minima. LNA V/VNA V incorporates
LNAV lateral with vertical path guidance for systems
and operators capable of either barometric or WAAS
vertical. Pilots are required to use WAAS to fly to the
LPV or LP minima. RNP APCH has a lateralaccuracy value of 1 in the terminal and missed
approach segments and essentially scales to RNP 0.3
in the final approach. (See paragraph 1 −1−18.)
(2) RNP AR APCH. RNP AR APCH
procedures are titled RNA V (RNP). RNP AR APCH
vertical navigation performance is based upon
barometric VNA V or W AAS. RNP AR is intended to
provide specific benefits at specific locations. It is not
intended for every operator or aircraft. RNP AR
capability requires specific aircraft performance,design, operational processes, training, and specific
procedure design criteria to achieve the required
target level of safety. RNP AR APCH has lateralaccuracy values that can range below 1 in the terminal
and missed approach segments and essentially scale
to RNP 0.3 or lower in the final approach. Operatorsconducting these approaches should refer to AC
90-101A, Approval Guidance for RNP Procedures
with AR . (See paragraph 5 −4−18.)
(3) Advanced RNP (A-RNP). Advanced
RNP includes a lateral accuracy value of 2 for oceanic
and remote operations but not planned for U.S.implementation and may have a 2 or 1 lateral
accuracy value for domestic enroute segments.
Except for the final approach, A-RNP allows forscalable RNP lateral navigation accuracies. Its
applications in the U.S. are still in progress.
(4) RNP 1 . RNP 1 requires a lateral
accuracy value of 1 for arrival and departure in theterminal area and the initial and intermediate
approach phase.
(5) RNP 2 . RNP 2 will apply to both
domestic and oceanic/remote operations with alateral accuracy value of 2.(6) RNP 4. RNP 4 will apply to oceanic and
remote operations only with a lateral accuracy value
of 4.
(7) RNP 0.3 . RNP 0.3 will apply to
rotorcraft only. This Nav Spec requires a lateral
accuracy value of 0.3 for all phases of flight except for
oceanic and remote and the final approach segment.
(b) Application of Standard Lateral Ac-
curacy Values. U.S. standard lateral accuracy values
typically used for various routes and procedures
supporting RNA V operations may be based on use of
a specific navigational system or sensor such as GPS,
or on multi −sensor RNA V systems having suitable
performance.
(c) Depiction of Lateral Accuracy Values.
The applicable lateral accuracy values will be
depicted on affected charts and procedures.
c. Other RNP Applications Outside the U.S.
The FAA and ICAO member states have ledinitiatives in implementing the RNP concept to
oceanic operations. For example, RNP −10 routes
have been established in the northern Pacific
(NOPAC) which has increased capacity and
efficiency by reducing the distance between tracksto 50 NM. (See paragraph 4 −7−1.)
d. Aircraft and Airborne Equipment Eligibility
for RNP Operations. Aircraft meeting RNP criteria
will have an appropriate entry including specialconditions and limitations in its Aircraft Flight
Manual (AFM), or supplement. Operators of aircraft
not having specific AFM −
RNP certification may be
issued operational approval including special condi-
tions and limitations for specific RNP lateral
accuracy values.
NOTE−
Some airborne systems use Estimated Position Uncer-
tainty (EPU) as a measure of the current estimated
navigational performance. EPU may also be r eferred to as
Actual Navigation Performance (ANP) or EstimatedPosition Error (EPE).
AIM 10/12/17
1−2−6 Performance −Based Navigation (PBN) and Area Navigation (RNA V)TBL 1−2−1
U.S. Standard RNP Levels
RNP Level Typical Application Primary Route
Width (NM) −
Centerline to
Boundary
0.1 to 1.0 RNP AR Approach Segments 0.1 to 1.0
0.3 to 1.0 RNP Approach Segments 0.3 to 1.0
1 Terminal and En Route 1.0
2 En Route 2.0
4 Projected for oceanic/remote areas where 30 NM horizontal
separation is applied.4.0
10 Oceanic/remote areas where 50 NM lateral separation is
applied.10.0
1−2−3. Use of Suitable Area Navigation
(RNAV) Systems on ConventionalProcedures and Routes
a. Discussion. This paragraph sets forth policy,
while providing operational and airworthiness
guidance regarding the suitability and use of RNA V
systems when operating on, or transitioning to,conventional, non −RNA V routes and procedures
within the U.S. National Airspace System (NAS):
1.Use of a suitable RNA V system as a
Substitute Means of Navigation when a Very −High
Frequency (VHF) Omni −directional Range (VOR),
Distance Measuring Equipment (DME), Tactical Air
Navigation (TACAN), VOR/TACAN (VORTAC),
VOR/DME, Non −directional Beacon (NDB), or
compass locator facility including locator outer
marker and locator middle marker is out −of−service
(that is, the navigation aid (NA V AID) information isnot available); an aircraft is not equipped with an
Automatic Direction Finder (ADF) or DME; or the
installed ADF or DME on an aircraft is notoperational. For example, if equipped with a suitable
RNA V system, a pilot may hold over an out −of−
service NDB.
2.Use of a suitable RNA V system as an
Alternate Means of Navigation when a VOR, DME,
VORTAC, VOR/DME, TACAN, NDB, or compass
locator facility including locator outer marker and
locator middle marker is operational and therespective aircraft is equipped with operational
navigation equipment that is compatible with
conventional navaids. For example, if equipped with
a suitable RNA V system, a pilot may fly a procedureor route based on operational VOR using that RNA V
system without monitoring the VOR.
NOTE−
1.Additional information and associated requirements
are available in Advisory Circular 90-108 titled “Use ofSuitable RNAV Systems on Conventional Routes andProcedures.”
2.Good planning and knowledge of your RNAV system are
critical for safe and successful operations.
3.Pilots planning to use their RNAV system as a substitute
means of navigation guidance in lieu of an out −of−service
NAVAID may need to advise ATC of this intent and
capability.
4.The navigation database should be current for the
duration of the flight. If the AIRAC cycle will change
during flight, operators and pilots should establish
procedures to ensure the accuracy of navigation data,including suitability of navigation facilities used to define
the routes and pr ocedures for flight. To facilitate validating
database currency, the F AA has developed procedures forpublishing the amendment date that instrument approach
procedures were last r evised. The amendment date follows
the amendment number, e.g., Amdt 4 14Jan10. Currency of
graphic departure procedures and STARs may be
ascertained by the numerical designation in the pr ocedure
title. If an amended chart is published for the pr ocedure, or
the procedure amendment date shown on the chart is on or
after the expiration date of the database, the operator must
not use the database to conduct the operation.
b. Types of RNA V Systems that Qualify as a
Suitable RNA V System. When installed in accord-
ance with appropriate airworthiness installation
requirements and operated in accordance with
applicable operational guidance (for example,aircraft flight manual and Advisory Circular
AIM 10/12/17
1−2−7 Performance −Based Navigation (PBN) and Area Navigation (RNA V)material), the following systems qualify as a suitable
RNA V system:
1.An RNA V system with TSO −C129/
−C145/−C146 equipment, installed in accordance
with AC 20 −138, Airworthiness Approval of Global
Positioning System (GPS) Navigation Equipment for
Use as a VFR and IFR Supplemental NavigationSystem, or AC 20 −130A, Airworthiness Approval of
Navigation or Flight Management Systems Integrat-
ing Multiple Navigation Sensors, and authorized forinstrument flight rules (IFR) en route and terminal
operations (including those systems previously
qualified for “GPS in lieu of ADF or DME”operations), or
2.An RNA V system with DME/DME/IRU
inputs that is compliant with the equipment
provisions of AC 90 −100A, U.S. Terminal and
En Route Area Navigation (RNA V) Operations, for
RNA V routes. A table of compliant equipment is
available at the following website:http://www.faa.gov/about/office_org/
headquarters_offices/avs/offices/afs/afs400/afs47
0/policy_guidance/
NOTE−
Approved RNAV systems using DME/DME/IRU, withoutGPS/WAAS position input, may only be used as a substitute
means of navigation when specifically authorized by aNotice to Airmen (NOTAM) or other F AA guidance for a
specific procedure. The NOTAM or other F AA guidance
authorizing the use of DME/DME/IRU systems will alsoidentify any required DME facilities based on an F AAassessment of the DME navigation infrastructure.
c. Uses of Suitable RNA V Systems. Subject to
the operating requirements, operators may use asuitable RNA V system in the following ways.
1.Determine aircraft position relative to, or
distance from a VOR (see NOTE 6 below), T ACAN,
NDB, compass locator, DME fix; or a named fixdefined by a VOR radial, TACAN course, NDB
bearing, or compass locator bearing intersecting a
VOR or localizer course.
2.Navigate to or from a VOR, TACAN, NDB,
or compass locator.
3.Hold over a VOR, TACAN, NDB, compass
locator, or DME fix.
4.Fly an arc based upon DME.NOTE−
1.The allowances described in this section apply even
when a facility is identified as r equired on a procedure (for
example, “Note ADF required”).
2.These operations do not include lateral navigation on
localizer−based courses (including localizer back −course
guidance) without reference to raw localizer data.
3.Unless otherwise specified, a suitable RNAV system
cannot be used for navigation on procedures that areidentified as not authorized (“NA”) without exception by
a NOTAM. For example, an operator may not use a RNAV
system to navigate on a pr ocedure affected by an expired or
unsatisfactory flight inspection, or a procedure that is
based upon a recently decommissioned NAVAID.
4.Pilots may not substitute for the NAVAID (for example,
a VOR or NDB) providing lateral guidance for the finalapproach segment. This restriction does not refer to
instrument approach pr ocedures with “or GPS” in the title
when using GPS or WAAS. These allowances do not apply
to procedures that are identified as not authorized (NA)without exception by a NOTAM, as other conditions may
still exist and result in a pr ocedure not being available. For
example, these allowances do not apply to a procedureassociated with an expired or unsatisfactory flight
inspection, or is based upon a recently decommissioned
NAVAID.
5.Use of a suitable RNAV system as a means to navigate
on the final approach segment of an instrument approach
procedure based on a VOR, TACAN or NDB signal, is
allowable. The underlying NAVAID must be operationaland the NAVAID monitored for final segment course
alignment.
6.For the purpose of paragraph c, “VOR” includes VOR,
VOR/DME, and VORTAC facilities and “compass
locator” includes locator outer marker and locator middle
marker .
d. Alternate Airport Considerations. For the
purposes of flight planning, any required alternateairport must have an available instrument approach
procedure that does not require the use of GPS. This
restriction includes conducting a conventionalapproach at the alternate airport using a substitute
means of navigation that is based upon the use of
GPS. For example, these restrictions would applywhen planning to use GPS equipment as a substitute
means of navigation for an out −of−service VOR that
supports an ILS missed approach procedure at analternate airport. In this case, some other approach
not reliant upon the use of GPS must be available.
This restriction does not apply to RNA V systems
AIM 10/12/17
1−2−8 Performance −Based Navigation (PBN) and Area Navigation (RNA V)using TSO −C145/−C146 WAAS equipment. For
further WAAS guidance, see paragraph 1 −1−18.
1.For flight planning purposes, TSO-C129()
and TSO-C196() equipped users (GPS users) whosenavigation systems have fault detection and
exclusion (FDE) capability, who perform a preflight
RAIM prediction at the airport where the RNA V(GPS) approach will be flown, and have proper
knowledge and any required training and/or approval
to conduct a GPS-based IAP, may file based on aGPS-based IAP at either the destination or the
alternate airport, but not at both locations. At the
alternate airport, pilots may plan for applicablealternate airport weather minimums using:
(a)Lateral navigation (LNA V) or circling
minimum descent altitude (MDA);
(b)LNA V/vertical navigation (LNA V/
VNA V) DA, if equipped with and using approved
barometric vertical navigation (baro-VNA V) equip-ment;
(c)RNP 0.3 DA on an RNA V (RNP) IAP, if
they are specifically authorized users using approved
baro-VNA V equipment and the pilot has verifiedrequired navigation performance (RNP) availability
through an approved prediction program.
2.If the above conditions cannot be met, any
required alternate airport must have an approved
instrument approach procedure other than GPS that is
anticipated to be operational and available at the
estimated time of arrival, and which the aircraft is
equipped to fly.
3.This restriction does not apply to
TSO-C145() and TSO-C146() equipped users
(WAAS users). For further WAAS guidance, see
paragraph 1 −1−18.
1−2−4. Pilots and Air Traffic Controllers
Recognizing Interference or Spoofing
a.Pilots need to maintain position awareness
while navigating. This awareness may be facilitated
by keeping relevant ground −based, legacy naviga-
tional aids tuned and available. By utilizing this
practice, situational awareness is promoted and
guards against significant pilot delay in recognizingthe onset of GPS interference. Pilots may find
cross−checks of other airborne systems (for example,
DME/DME/IRU or VOR) useful to mitigate this
otherwise undetected hazard.
REFERENCE −
AIM Paragraph 1 −1−17, Global Positioning System (GPS)
AIM Paragraph 1 −1−18, Wide Area Augmentation System (WAAS)
b.During preflight planning, pilots should be
particularly alert for NOTAMs which could affect
navigation (GPS or WAAS) along their route offlight, such as Department of Defense electronic
signal tests with GPS.
REFERENCE −
AIM Paragraph 1 −1−17, Global Positioning System (GPS)
AIM Paragraph 1 −1−18, Wide Area Augmentation System (WAAS)
c.If the pilot experiences interruptions while
navigating with GPS, the pilot and ATC may both
incur a higher workload. In the aircraft, the pilot may
need to change to ground −based NAVAIDs (for
example, DME/DME/IRU or VOR). If the pilot’s
aircraft is under ATC radar or multilateration
surveillance, ATC may be able to provide radar
vectors out of the interference affected area or to analternate destination upon pilot request. An ADS −B
Out aircraft’s broadcast information may be incorrect
and should not be relied upon for surveillance wheninterference or spoofing is suspected unless its
accuracy can be verified by independent means.
During the approach phas e, a pilot might elect to
continue in visual conditions or may need to execute
the published missed approach. If the published
missed approach procedure is GPS −based, the pilot
will need alternate instructions. If the pilot were to
choose to continue in visual conditions, the pilot
could aid the controller by cancelling his/her IFRflight plan and proceeding to the airport to land. A TC
would cancel the pilot’s IFR clearance and issue a
VFR squawk; freeing up the controller to handleother aircraft.
d.The FAA requests that pilots notify ATC if they
experience interruptions to their GPS navigation or
surveillance. GPS interference or outages associated
with a known testing NOTAM should not be reported
to ATC unless the interference/outage affects the
pilot’s ability to navigate his/her aircraft.
REFERENCE −
AIM Paragraph 1 −1−13, User Reports Requested on NAVAID or Global
Navigation Satellite System (GNSS) Performance or Interference.
AIM 10/12/17
2−1−1 Airport Lighting AidsChapter 2. Aeronautical Lighting and
Other Airport Visual Aids
Section 1. Airport Lighting Aids
2−1−1. Approach Light Systems (ALS)
a.ALS provide the basic means to transition from
instrument flight to visual flight for landing.Operational requirements dictate the sophistication
and configuration of the approach light system for a
particular runway.
b.ALS are a configuration of signal lights starting
at the landing threshold and extending into the
approach area a distance of 2400 −3000 feet for
precision instrument runways and 1400 −1500 feet for
nonprecision instrument runways. Some systems
include sequenced flashing lights which appear to the
pilot as a ball of light traveling towards the runway at
high speed (twice a second). (See FIG 2−1−1.)
2−1−2. Visual Glideslope Indicators
a. Visual Approach Slope Indicator (V ASI)
1.V ASI installations may consist of either 2, 4,
6, 12, or 16 light units arranged in bars referred to as
near, middle, and far bars. Most V ASI installationsconsist of 2 bars, near and far, and may consist of 2,
4, or 12 light units. Some V ASIs consist of three bars,
near, middle, and far, which provide an additionalvisual glide path to accommodate high cockpit
aircraft. This installation may consist of either 6 or
16 light units. V ASI installations consisting of 2, 4, or
6 light units are located on one side of the runway,
usually the left. Where the installation consists of
12 or 16 light units, the units are located on both sidesof the runway.
2.Two−bar V ASI installations provide one
visual glide path which is normally set at 3 degrees.
Three−bar V ASI installations provide two visual
glide paths. The lower glide path is provided by the
near and middle bars and is normally set at 3 degreeswhile the upper glide path, provided by the middle
and far bars, is normally
1/4 degree higher. This
higher glide path is intended for use only by high
cockpit aircraft to provide a sufficient threshold
crossing height. Although normal glide path anglesare three degrees, angles at some locations may be as
high as 4.5 degrees to give proper obstacle clearance.
Pilots of high performance aircraft are cautioned that
use of V ASI angles in excess of 3.5 degrees may cause
an increase in runway length required for landing and
rollout.
3.The basic principle of the V ASI is that of color
differentiation between red and white. Each light unit
projects a beam of light having a white segment in the
upper part of the beam and red segment in the lower
part of the beam. The light units are arranged so that
the pilot using the V ASIs during an approach will seethe combination of lights shown below.
4.The V ASI is a system of lights so arranged to
provide visual descent guidance information during
the approach to a runway. These lights are visible
from 3−5 miles during the day and up to 20 miles or
more at night. The visual glide path of the V ASI
provides safe obstruction clearance within plus or
minus 10 degrees of the extended runway centerlineand to 4 NM from the runway threshold. Descent,
using the V ASI, should not be initiated until the
aircraft is visually aligned with the runway. Lateralcourse guidance is provided by the runway or runway
lights. In certain circumstances, the safe obstruction
clearance area may be reduced by narrowing thebeam width or shortening the usable distance due to
local limitations, or the V ASI may be offset from the
extended runway centerline. This will be noted in the
Chart Supplement U.S. and/or applicable notices to
airmen (NOTAM).
AIM 10/12/17
2−1−2 Airport Lighting AidsFIG 2−1−1
Precision & Nonprecision Configurations
NOTE−
Civil ALSF −2 may be operated as SSALR during favorable weather conditions.
AIM 10/12/17
2−1−3 Airport Lighting Aids5.For 2−bar V ASI (4 light units) see FIG 2−1−2.
FIG 2−1−2
2−Bar VASI
Far Bar
= Red
= WhiteNear Bar
Below Glide Path On Glide Path Above Glide Path
6.For 3−bar V ASI (6 light units) see FIG 2−1−3.
FIG 2−1−3
3−Bar VASI
Far Bar
Middle Bar
Near Bar
Below Both
Glide PathsOn Lower
Glide PathOn Upper
Glide PathAbove Both
Glide Paths
7.For other V ASI configurations see FIG 2−1−4.
FIG 2−1−4
V ASI Variations
2 Bar
2 Light Units
On Glide Path2 Bar
12 Light Units
On Glide Path3 Bar
16 Light Units
on Lower Glide Path
AIM 10/12/17
2−1−4 Airport Lighting Aidsb. Precision Approach Path Indicator (PAPI).
The precision approach path indicator (PAPI) uses
light units similar to the V ASI but are installed in a
single row of either two or four light units. These
lights are visible from about 5 miles during the dayand up to 20 miles at night. The visual glide path of
the PAPI typically provides safe obstruction
clearance within plus or minus 10 degrees of theextended runway centerline and to 3.4 NM from the
runway threshold. Descent, using the PAPI, should
not be initiated until the aircraft is visually alignedwith the runway. The row of light units is normally
installed on the left side of the runway and the glide
path indications are as depicted. Lateral course
guidance is provided by the runway or runway lights.
In certain circumstances, the safe obstructionclearance area may be reduced by narrowing the
beam width or shortening the usable distance due to
local limitations, or the PAPI may be offset from theextended runway centerline. This will be noted in the
Chart Supplement U.S. and/or applicable NOTAMs.
(See FIG 2−1−5.)
FIG 2−1−5
Precision Approach Path Indicator (PAPI)
Slightly High
(3.2 Degrees)
White
RedHigh
(More Than
3,5 Degrees)On Glide Path
(3 Degrees)Slightly Low
(2.8 Degrees)Low
(Less Than
2.5 Degrees)
c. Tri−color Systems. Tri−color visual approach
slope indicators normally consist of a single light unit
projecting a three−color visual approach path into the
final approach area of the runway upon which the
indicator is installed. The below glide path indication
is red, the above glide path indication is amber, andthe on glide path indication is green. These types of
indicators have a useful range of approximately
one−half to one mile during the day and up to
five miles at night depending upon the visibility
conditions. (See FIG 2−1−6.)
FIG 2−1−6
Tri−Color V isual Approach Slope Indicator
Amber
Above Glide PathOn Glide Path
Below Glide PathAmberGreen
Red
NOTE−
1.Since the tri−color V ASI consists of a single light source which could possibly be confused with other light sources, pilots
should exercise care to properly locate and identify the light signal.
AIM 10/12/17
2−1−5 Airport Lighting Aids2.When the aircraft descends from green to red, the pilot may see a dark amber color during the transition from green to
red.
FIG 2−1−7
Pulsating Visual Approach Slope Indicator
Above Glide Path
On Glide Path
Below Glide PathSlightly Below Glide Path
ThresholdPULSATING WHITE
PULSATING REDSTEADY WHITE
STEADY RED
NOTE−
Since the PVASI consists of a single light source which could possibly be confused with other light sources, pilots should
exercise care to properly locate and identify the light signal.
FIG 2−1−8
Alignment of Elements
Below Glide Path On Glide Path Above Glide Path
d. Pulsating Systems. Pulsating visual ap-
proach slope indicators normally consist of a single
light unit projecting a two −color visual approach
path into the final approach area of the runway upon
which the indicator is installed. The on glide pathindication is a steady white light. The slightly below
glide path indication is a steady red light. If the
aircraft descends further below the glide path, the red
light starts to pulsate. The above glide path indication
is a pulsating white light. The pulsating rate increases
as the aircraft gets further above or below the desiredglide slope. The useful range of the system is about
four miles during the day and up to ten miles at night.
(See FIG 2−1−7.)
e. Alignment of Elements Systems. Alignment
of elements systems are installed on some small
general aviation airports and are a low −cost system
consisting of painted plywood panels, normally black
and white or fluorescent orange. Some of these
systems are lighted for night use. The useful range of
these systems is approximately three −quarter miles.
AIM 10/12/17
2−1−6 Airport Lighting AidsTo use the system the pilot positions the aircraft so the
elements are in alignment. The glide path indications
are shown in FIG 2−1−8.
2−1−3. Runway End Identifier Lights (REIL)
REILs are installe d at many airfields to provide rapid
and positive identification of the approach end of a
particular runway. The system consists of a pair of
synchronized flashing lights located laterally on each
side of the runway threshold. REILs may be eitheromnidirectional or unidirectional facing the approach
area. They are effective for:
a.Identification of a runway surrounded by a
preponderance of other lighting.
b.Identification of a runway which lacks contrast
with surrounding terrain.
c.Identification of a runway during reduced
visibility.
2−1−4. Runway Edge Light Systems
a.Runway edge lights are used to outline the
edges of runways during periods of darkness or
restricted visibility conditions. These light systems
are classified according to the intensity or brightnessthey are capable of producing: they are the High
Intensity Runway Lights (HIRL), Medium Intensity
Runway Lights (MIRL), and the Low IntensityRunway Lights (LIRL). The HIRL and MIRL
systems ha ve variable intensity controls, whereas the
LIRLs normally have one intensity setting.
b.The runway edge lights are white, except on
instrument runways yellow replaces white on the last
2,000 feet or half the runway length, whichever is
less, to form a caution zone for landings.
c.The lights marking the ends of the runway emit
red light toward the runway to indicate the end of
runway to a departing aircraft and emit green outward
from the runway end to indicate the threshold to
landing aircraft.
2−1−5. In−runway Lighting
a. Runway Centerline Lighting System
(RCLS). Runway centerline lights are installed on
some precision approach runways to facilitatelanding under adverse visibility conditions. They are
located along the runway centerline and are spaced at
50−foot intervals. When viewed from the landingthreshold, the runway centerline lights are white until
the last 3,000 feet of the runway. The white lights
begin to alternate with red for the next 2,000 feet, and
for the last 1,000 feet of the runway, all centerline
lights are red.
b. Touchdown Zone Lights (TDZL). Touch-
down zone lights are installed on some precision
approach runways to indicate the touchdown zonewhen landing under adverse visibility conditions.
They consist of two rows of transverse light bars
disposed symmetrically about the runway centerline.
The system consists of steady −burning white lights
which
start 100 feet beyond the landing threshold and
extend to 3,000 feet beyond the landing threshold orto the midpoint of the runway, whichever is less.
c. Taxiway Centerline Lead −Off Lights. Taxi-
way centerline lead −off lights provide visual
guidance to persons exiting the runway. They are
color−coded to warn pilots and vehicle drivers that
they are within the runway environment orinstrument landing system (ILS) critical area,
whichever is more restrictive. Alternate green and
yellow lights are installed, beginning with green,from the runway centerline to one centerline light
position beyond the runway holding position or ILS
critical area holding position.
d. Taxiway Centerline Lead −On Lights. Taxi-
way centerline lead −on lights provide visual
guidance to persons entering the runway. These
“lead−on” lights are also color −coded with the same
color pattern as lead −off lights to warn pilots and
vehicle drivers that they are within the runway
environment or instrument landing system (ILS)
critical area, whichever is more conservative. Thefixtures used for lead −on lights are bidirectional, i.e.,
one side emits light for the lead −on function while the
other side emits light for the lead −off function. Any
fixture that emits yellow light for the lead −off
function must also emit yellow light for the lead −on
function. (See FIG 2−1−14.)
e. Land and Hold Short Lights. Land and hold
short lights are used to indicate the hold short point on
certain runways which are approved for Land andHold Short Operations (LAHSO). Land and hold
short lights consist of a row of pulsing white lights
installed across the runway at the hold short point.Where installed, the lights will be on anytime
LAHSO is in effect. These lights will be off when
LAHSO is not in effect.
AIM 10/12/17
2−1−7 Airport Lighting AidsREFERENCE −
AIM, Paragraph 4 −3−11 , Pilot Responsibilities When Conducting Land
and Hold Short Operations (LAHSO)
2−1−6. Runway Status Light (RWSL)
System
a.Introduction.
RWSL is a fully automated system that provides
runway status information to pilots and surface
vehicle operators to clearly indicate when it is unsafe
to enter, cross, takeoff from, or land on a runway. The
RWSL system processes information from surveil-
lance systems and activates Runway Entrance Lights
(REL), Takeoff Hold Lights (THL), Runway
Intersection Lights (RIL), and Final Approach
Runway Occupancy Signal (FAROS) in accordancewith the position and velocity of the detected surface
traffic and approach traffic. REL, THL, and RIL are
in-pavement light fixtures that are directly visible topilots and surface vehicle operators. FAROS alerts
arriving pilots that the approaching runway is
occupied by flashing the Precision Approach PathIndicator (PAPI). FAROS may be implemented as an
add-on to the RWSL system or implemented as a
stand-alone system at airports without a RWSLsystem. RWSL is an independent safety enhancement
that does not substitute for or convey an ATC
clearance. Clearance to enter, cross, takeoff from,land on, or operate on a runway must still be received
from ATC. Although ATC has limited control over
the system, personnel do not directly use and may not
be able to view light fixture activations and
deactivations during the conduct of daily ATC
operations.
b.Runway Entrance Lights (REL): The REL
system is composed of flush mounted, in-pavement,
unidirectional light fixtures that are parallel to and
focused along the taxiway centerline and directedtoward the pilot at the hold line. An array of REL
lights include the first light at the hold line followed
by a series of evenly spaced lights to the runway edge;
one additional light at the runway centerline is in line
with the last two lights before the runway edge (see
FIG 2−1−9 and FIG 2 −1−12). When activated, the
red lights indicate that there is high speed traffic on
the runway or there is an aircraft on final approach
within the activation area.
1.REL Operating Characteristics − Departing
Aircraft:When a departing aircraft reaches a site adaptable
speed of approximately 30 knots, all taxiway
intersections with REL arrays along the runway
ahead of the aircraft will illuminate (see FIG 2 −1−9).
As the aircraft approaches an REL equipped taxiwayintersection, the lights at that intersection extinguish
approximately 3 to 4 seconds before the aircraft
reaches it. This allows controllers to apply“anticipated separation” to permit ATC to move
traffic more expeditiously without compromising
safety. After the aircraft is declared “airborne” by the
system, all REL lights associated with this runway
will extinguish.
2.REL Operating Characteristics − Arriving
Aircraft:
When an aircraft on final approach is approximately
1 mile from the runway threshold, all sets of taxiway
REL light arrays that intersect the runway illuminate.
The distance is adjustable and can be configured forspecific operations at particular airports. Lights
extinguish at each equipped taxiway intersection
approximately 3 to 4 seconds before the aircraftreaches it to apply anticipated separation until the
aircraft has slowed to approximately 80 knots (site
adjustable parameter). Below 80 knots, all arrays that
are not within 30 seconds of the aircraft’s forward
path are extinguished. Once the arriving aircraft
slows to approximately 34 knots (site adjustable
parameter), it is declared to be in a taxi state, and all
lights extinguish.
3.What a pilot would observe: A pilot at or
approaching the hold line to a runway will observe
RELs illuminate and extinguish in reaction to anaircraft or vehicle operating on the runway, or an
arriving aircraft operating less than 1 mile from the
runway threshold.
4.When a pilot observes the red lights of the
REL, that pilot will stop at the hold line or remain
stopped. The pilot will then contact ATC forresolution if the clearance is in conflict with the
lights. Should pilots note illuminated lights under
circumstances when remaining clear of the runway is
impractical for safety reasons (for example, aircraft
is already on the runway), the crew should proceed
according to their best judgment while understanding
the illuminated lights indicate the runway is unsafe to
enter or cross. Contact ATC at the earliest possible
opportunity.
AIM 10/12/17
2−1−8 Airport Lighting AidsFIG 2−1−9
Runway Status Light System
c.Takeoff Hold Lights (THL) : The THL system
is composed of flush mounted, in-pavement,
unidirectional light fixtures in a double longitudinal
row aligned either side of the runway centerline
lighting. Fixtures are focused toward the arrival endof the runway at the “line up and wait” point. THLs
extend for 1,500 feet in front of the holding aircraft
starting at a point 375 feet from the departurethreshold (see FIG 2−1−13). Illuminated red lights
provide a signal, to an aircraft in position for takeoff
or rolling, that it is unsafe to takeoff because the
runway is occupied or about to be occupied by
another aircraft or ground vehicle. Two aircraft, or a
surface vehicle and an aircraft, are required for thelights to illuminate. The departing aircraft must be in
position for takeoff or beginning takeoff roll. Another
aircraft or a surface vehicle must be on or about tocross the runway.
1.THL Operating Characteristics − Departing
Aircraft:
THLs will illuminate for an aircraft in position for
departure or departing when there is another aircraft
or vehicle on the runway or about to enter the runway
(see FIG 2−1−9.) Once that aircraft or vehicle exits
the runway, the THLs extinguish. A pilot may noticelights extinguish prior to the downfield aircraft or
vehicle being completely clear of the runway but still
moving. Like RELs, THLs have an “anticipated
separation” feature.
NOTE−
When the THLs extinguish, this is not clearance to begin a
takeoff roll. All takeoff clearances will be issued by ATC.
2.What a pilot would observe: A pilot in
position to depart from a runway, or has begun takeoff
roll, will observe THLs illuminate in reaction to an
aircraft or vehicle on the runway or entering orcrossing it. Lights will extinguish when the runway is
clear. A pilot may observe several cycles of
illumination and extinguishing depending on the
amount of crossing traffic.
3.When a pilot observes the red light of the
THLs, the pilot should safely stop if it’s feasible or
remain stopped. The pilot must contact ATC forresolution if any clearance is in conflict with the
lights. Should pilots note illuminated lights while in
takeoff roll and under circumstances when stopping
is impractical for safety reasons, the crew should
proceed according to their best judgment whileunderstanding the illuminated lights indicate that
AIM 10/12/17
2−1−9 Airport Lighting Aidscontinuing the takeoff is unsafe. Contact ATC at the
earliest possible opportunity.
d.Runway Intersection Lights (RIL): The RIL
system is composed of flush mounted, in −pavement,
unidirectional light fixtures in a double longitudinalrow aligned either side of the runway centerline
lighting in the same manner as THLs. Their
appearance to a pilot is similar to that of THLs.Fixtures are focused toward the arrival end of the
runway, and they extend for 3,000 feet in front of an
aircraft that is approaching an intersecting runway.They end at the Land and Hold Short Operation
(LASHO) light bar or the hold short line for the
intersecting runway.
1.RIL Operating Characteristics − Departing
Aircraft:
RILs will illuminate for an aircraft departing or in
position to depart when there is high speed traffic
operating on the intersecting runway (seeFIG 2−1−9). Note that there must be an aircraft or
vehicle in a position to observe the RILs for them to
illuminate. Once the conflicting traffic passesthrough the intersection, the RILs extinguish.
2.RIL Operating Characteristics − Arriving
Aircraft:
RILs will illuminate for an aircraft that has landed and
is rolling out when there is high speed traffic on the
intersecting runway that is /C00365 seconds of meeting at
the intersection. Once the conflicting traffic passes
through the intersection, the RILs extinguish.
3.What a pilot would observe: A pilot departing
or arriving will observe RILs illuminate in reaction to
the high speed traffic operation on the intersectingrunway. The lights will extinguish when that traffic
has passed through the runway intersection.
4.Whenever a pilot observes the red light of the
RIL array, the pilot will stop before the LAHSO stop
bar or the hold line for the intersecting runway. If a
departing aircraft is already at high speed in thetakeoff roll when the RILs illuminate, it may be
impractical to stop for safety reasons. The crew
should safely operate according to their bestjudgment while understanding the illuminated lights
indicate that continuing the takeoff is unsafe. Contact
ATC at the earliest possible opportunity.e.The Final Approach Runway Occupancy Signal
(FAROS) is communicated by flashing of the
Precision Approach Path Indicator (PAPI) (see FIG
2-1-9). When activated, the light fixtures of the PAPI
flash or pulse to indicate to the pilot on an approachthat the runway is occupied and that it may be unsafe
to land.
NOTE−
F AROS is an independent automatic alerting system that
does not rely on ATC control or input.
1.FAROS Operating Characteristics:
If an aircraft or surface vehicle occupies a FAROS
equipped runway, the PAPI(s) on that runway willflash. The glide path indication will not be affected,
and the allotment of red and white PAPI lights
observed by the pilot on approach will not change.The FAROS system will flash the PAPI when traffic
enters the runway and there is an aircraft on approach
and within 1.5 nautical miles of the landing threshold.
2.What a pilot would observe: A pilot on
approach to the runway will observe the PAPI flash if
there is traffic on the runway and will notice the PAPI
ceases to flash when the traffic moves outside thehold short lines for the runway.
3.When a pi lot observes a flashing PAPI at 500
feet above ground level (AGL), the contact height,
the pilot must look for and acquire the traffic on therunway. At 300 feet AGL, the pilot must contact ATC
for resolution if the FAROS indication is in conflict
with the clearance. If the PAPI continues to flash, the
pilot must execute an immediate “go around” and
contact ATC at the earliest possible opportunity.
f.Pilot Actions:
1.When operating at airports with RWSL, pilots
will operate with the transponder “On” when
departing the gate or parking area until it is shutdown
upon arrival at the gate or parking area. This ensures
interaction with the FAA surveillance systems such
as ASDE-X/Airport Surface Surveillance Capability(ASSC) which provide information to the RWSL
system.
2.Pilots must always inform the ATCT when
they have either stopped, are verifying a landing
clearance, or are executing a go-around due to RWSL
or FAROS indication that are in conflict with ATC
instructions. Pilots must request clarification of the
taxi, takeoff, or landing clearance.
AIM 10/12/17
2−1−10 Airport Lighting Aids3.Never cross over illuminated red lights.
Under normal circumstances, RWSL will confirm the
pilot’s taxi or takeoff clearance previously issued by
ATC. If RWSL indicates that it is unsafe to takeoff
from, land on, cross, or enter a runway, immediatelynotify ATC of the conflict and re-confirm the
clearance.
4.Do not proceed when lights have extin-
guished without an A TC clearance. RWSL verifies an
ATC clearance; it does not substitute for an ATCclearance.
5.Never land if PAPI continues to flash.
Execute a go around and notify ATC.
g.ATC Control of RWSL System:
1.Controllers can set in−pavement lights to one
of five (5) brightness levels to assure maximumconspicuity under all visibility and lighting condi-
tions. REL, THL, and RIL subsystems may be
independently set.
2.System lights can be disabled should RWSL
operations impact the efficient movement of airtraffic or contribute, in the opinion of the assigned
ATC Manager, to unsafe operations. REL, THL, RIL,
and FAROS light fixtures may be disabled separately.Disabling of the FAROS subsystem does not
extinguish PAPI lights or impact its glide path
function. Whenever the system or a component is
disabled, a NOTAM must be issued, and theAutomatic Terminal Information System (ATIS)
must be updated.
2−1−7. Stand-Alone Final Approach
Runway Occupancy Signal (FAROS)
a.Introduction:
The stand-alone FAROS system is a fully automated
system that provides runway occupancy status to
pilots on final approach to indicate whether it may be
unsafe to land. When an aircraft or vehicle is detected
on the runway, the Precision Approach Path Indicator
(PAPI) light fixtures flash as a signal to indicate that
the runway is occupied and that it may be unsafe to
land. The stand-alone FAROS system is activated by
localized or comprehensive sensors detecting aircraft
or ground vehicles occupying activation zones.
The stand-alone FAROS system monitors specific
areas of the runway, called activation zones, to
determine the presence of aircraft or ground vehicles
in the zone (see FIG 2 −1−10). These activation zones
are defined as areas on the runway that are frequently
occupied by ground traffic during normal airportoperations and could present a hazard to landing
aircraft. Activation zones may include the full-length
departure position, the midfield departure position, a
frequently crossed intersection, or the entire runway.
Pilots can refer to the airport specific FAROS pilot
information sheet for activation zone configuration.
FIG 2−1−10
FAROS Activation Zones
Clearance to land on a runway must be issued by Air
Traffic Control (ATC). ATC personnel have limitedcontrol over the system and may not be able to view
the FAROS signal.
AIM 10/12/17
2−1−11 Airport Lighting Aidsb.Operating Characteristics:
If an aircraft or ground vehicle occupies an activation
zone on the runway, the PAPI light fixtures on that
runway will flash. The glide path indication is notaffected, i.e. the configuration of red and white PAPI
lights observed by the pilot on approach does not
change. The stand-alone FAROS system flashes thePAPI lights when traffic occupies an activation zone
whether or not there is an aircraft on approach.
c.Pilot Observations:
A pilot on approach to the runway observes the PAPI
lights flashing if there is traffic on the runway
activation zones and notices the PAPI lights cease to
flash when the traffic moves outside the activation
zones.A pilot on departure from the runway should
disregard any observations of flashing PAPI lights.
d.Pilot Actions:
When a pilot observes a flashing PAPI at 500 feet
above ground level (AGL), the pilot must look for and
attempt to acquire the traffic on the runway. At 300
feet AGL, the pilot must contact ATC for resolutionif the FAROS indication is in conflict with the
clearance (see FIG 2 −1−11). If the PAPI lights
continue to flash and the pilot cannot visuallydetermine that it is safe to land, the pilot must execute
an immediate “go around”. As with operations at
non-FAROS airports, it is always the pilot’sresponsibility to determine whether or not it is safe to
continue w ith the approach an d to land on the runway.
FIG 2−1−11
FAROS Glide Slope Action Points
Pilots should inform the ATCT when they have
executed a go around due to a F AROS indication that
is in conflict with ATC instructions.
NOTE−
At this time, the stand-alone F AROS system is not widely
implemented and is used for evaluation purposes.
2−1−8. Control of Lighting Systems
a.Operation of approach light systems and
runway lighting is controlled by the control tower(ATCT). At some locations the FSS may control the
lights where there is no control tower in operation.
b.Pilots may request that lights be turned on or off.
Runway edge lights, in −pavement lights and
approach lights also have intensity controls which
may be varied to meet the pilots request. Sequencedflashing lights (SFL) may be turned on and off. Some
sequenced flashing light systems also have intensity
control.
2−1−9. Pilot Control of Airport Lighting
Radio control of lighting is available at selected
airports to provide airborne control of lights by
keying the aircraft’s microphone. Control of lighting
systems is often available at locations without
specified hours for lighting and where there is no
control tower or FSS or when the tower or FSS isclosed (locations with a part −time tower or FSS) or
specified hours. All lighting systems which are radio
controlled at an airport, whether on a single runwayor multiple runways, operate on the same radio
frequency. (See TBL 2 −1−1 and TBL 2 −1−2.)
AIM 10/12/17
2−1−12 Airport Lighting AidsFIG 2−1−12
Runway Entrance Lights
FIG 2−1−13
Takeoff Hold Lights
AIM 10/12/17
2−1−13 Airport Lighting AidsFIG 2−1−14
Taxiway Lead −On Light Configuration
TBL 2−1−1
Runways With Approach Lights
Lighting SystemNo. of Int.
StepsStatus During
Nonuse PeriodIntensity Step Selected Per No. of Mike Clicks
3 Clicks 5 Clicks 7 Clicks
Approach Lights (Med. Int.) 2 Off Low Low High
Approach Lights (Med. Int.) 3 Off Low Med High
MIRL 3 Off or Low /C0117 /C0117 /C0117
HIRL 5 Off or Low /C0117 /C0117 /C0117
V ASI 2 Off /C0076 /C0076 /C0076
NOTES :/C0117Predetermined intensity step.
/C0076Low intensity for night use. High intensity for day use as determined by photocell control.
TBL 2−1−2
Runways Without Approach Lights
Lighting SystemNo. of Int.
StepsStatus During
Nonuse PeriodIntensity Step Selected Per No. of Mike Clicks
3 Clicks 5 Clicks 7 Clicks
MIRL 3 Off or Low Low Med. High
HIRL 5 Off or Low Step 1 or 2 Step 3 Step 5
LIRL 1 Off On On On
V ASI/C0076 2 Off /C0117 /C0117 /C0117
REIL/C0076 1 Off Off On/Off On
REIL/C0076 3 Off Low Med. High
NOTES :/C0117 Low intensity for night use. High intensity for day use as determined by photocell control.
/C0076 The control of V ASI and/or REIL may be independent of other lighting systems.
AIM 10/12/17
2−1−14 Airport Lighting Aidsa.With FAA approved systems, various combina-
tions of medium intensity approach lights, runway
lights, taxiway lights, V ASI and/or REIL may be
activated by radio control. On runways with both
approach lighting and runway lighting (runway edge
lights, taxiway lights, etc.) systems, the approach
lighting system takes precedence for air −to−ground
radio control over the runway lighting system whichis set at a predetermined intensity step, based on
expected visibility conditions. Runways without
approach lighting may provide radio controlledintensity adjustments of runway edge lights. Other
lighting systems, including V ASI, REIL, and taxiway
lights may be either controlled with the runway edge
lights or controlled independently of the runway edge
lights.
b.The control system consists of a 3 −step control
responsive to 7, 5, and/or 3 microphone clicks. This
3−step control will turn on lighting facilities capable
of either 3 −step, 2−step or 1 −step operation. The
3−step and 2 −step lighting facilities can be altered in
intensity, while the 1 −step cannot. All lighting is
illuminated for a period of 15 minutes from the most
recent time of activation and may not be extinguished
prior to end of the 15 minute period (except for 1 −step
and 2−step REILs which may be turned off when
desired by keying the mike 5 or 3 times respectively).
c.Suggested use is to always initially key the mike
7 times; this assures that all controlled lights are
turned on to the maximum available intensity. If
desired, adjustment can then be made, where the
capability is provided, to a lower intensity (or theREIL turned off) by keying 5 and/or 3 times. Due to
the close proximity of airports using the same
frequency, radio controlled lighting receivers may be
set at a low sensitivity requiring the aircraft to be
relatively close to activate the system. Consequently,
even when lights are on, always key mike as directedwhen overflying an airport of intended landing or just
prior to entering the final segment of an approach.
This will assure the aircraft is close enough to activate
the system and a full 15 minutes lighting duration is
available. Approved lighting systems may be
activated by keying the mike (within 5 seconds) asindicated in TBL 2 −1−3.TBL 2−1−3
Radio Control System
Key Mike Function
7 times within 5 seconds Highest intensity available
5 times within 5 seconds Medium or lower intensity
(Lower REIL or REIL −off)
3 times within 5 seconds Lowest intensity available
(Lower REIL or REIL −off)
d.For all public use airports with FAA standard
systems the Chart Supplement U.S. contains the types
of lighting, runway and the frequency that is used to
activate the system. Airports with IAPs include data
on the approach chart identifying the light system, the
runway on which they are installed, and the frequency
that is used to activate the system.
NOTE−
Although the CTAF is used to activate the lights at many
airports, other frequencies may also be used. Theappropriate frequency for activating the lights on theairport is provided in the Chart Supplement U.S. and thestandard instrument approach procedures publications. It
is not identified on the sectional charts.
e.Where the airport is not served by an IAP, it may
have either the standard FAA approved control
system or an independent type system of different
specification installed by the airport sponsor. TheChart Supplement U.S. contains descriptions of pilot
controlled lighting systems for each airport having
other than FAA approved systems, and explains thetype lights, method of control, and operating
frequency in clear text.
2−1−10. Airport/Heliport Beacons
a.Airport and heliport beacons have a vertical
light distribution to make them most effective from
one to ten degrees above the horizon; however, they
can be seen well above and below this peak spread.The beacon may be an omnidirectional capacitor −dis-
charge device, or it may rotate at a constant speed
which produces the visual ef fect of flashes at regular
intervals. Flashes may be one or two colors
alternately. The total number of flashes are:
1.24 to 30 per minute for beacons marking
airports, landmarks, and points on Federal airways.
2.30 to 45 per minute for beacons marking
heliports.
AIM 10/12/17
2−1−15 Airport Lighting Aidsb.The colors and color combinations of beacons
are:
1.White and Green − Lighted land airport.
2.*Green alone − Lighted land airport.
3.White and Yellow − Lighted water airport.
4.*Yellow alone − Lighted water airport.
5.Green, Yellow, and White − Lighted heliport.
NOTE−
*Green alone or yellow alone is used only in connectionwith a white −and−green or white −and−yellow beacon
display, respectively.
c.Military airport beacons flash alternately white
and green, but are differentiated from civil beaconsby dualpeaked (two quick) white flashes between the
green flashes.
d.In Class B, Class C, Class D and Class E surface
areas, operation of the airport beacon during the hours
of daylight often indicates that the ground visibility
is less than 3 miles and/or the ceiling is less than1,000 feet. ATC clearance in accordance with
14 CFR Part 91 is required for landing, takeoff and
flight in the traffic pattern. Pilots should not relysolely on the operation of the airport beacon to
indicate if weather conditions are IFR or VFR. At
some locations with operating control towers, ATCpersonnel turn the beacon on or off when controls are
in the tower. At many airports the airport beacon is
turned on by a photoelectric cell or time clocks andATC personnel cannot control them. There is no
regulatory requirement for daylight operation and it
is the pilot’s responsibility to comply with properpreflight planning as required by 14 CFR
Section 91.103.
2−1−11. Taxiway Lights
a. Taxiway Edge Lights. Taxiway edge lights are
used to outline the edges of taxiways during periods
of darkness or restricted visibility conditions. Thesefixtures emit blue light.
NOTE−
At most major airports these lights have variable intensity
settings and may be adjusted at pilot request or when
deemed necessary by the controller.
b. Taxiway Centerline Lights. Taxiway center-
line lights are used to facilitate ground traffic under
low visibility conditions. They are located along the
taxiway centerline in a straight line on straightportions, on the centerline of curved portions, and
along designated taxiing paths in portions of
runways, ramp, and apron areas. Taxiway centerline
lights are steady burning and emit green light.
c. Clearance Bar Lights. Clearance bar lights
are installed at holding positions on taxiways in order
to increase the conspicuity of the holding position in
low visibility conditions. They may also be installed
to indicate the location of an intersecting taxiway
during periods of darkness. Clearance bars consist of
three in−pavement steady −burning yellow lights.
d. Runway Guard Lights. Runway guard lights
are installed at taxiway/runway intersections. They
are primarily used to enhance the conspicuity of
taxiway/runway intersections during low visibilityconditions, but may be used in all weather conditions.
Runway guard lights consist of either a pair of
elevated flashing yellow lights installed on either side
of the taxiway, or a row of in −pavement yellow lights
installed across the entire taxiway, at the runway
holding position marking.
NOTE−
Some airports may have a row of three or five in −pavement
yellow lights installed at taxiway/runway intersections.They should not be confused with clearance bar lights
described in paragraph 2 −1−1 1 c, Clearance Bar Lights.
e. Stop Bar Lights. Stop bar lights, when
installed, are used to confirm the ATC clearance toenter or cross the active runway in low visibility
conditions (below 1,200 ft Runway Visual Range). A
stop bar consists of a row of red, unidirectional,
steady−burning in −pavement lights installed across
the entire taxiway at the runway holding position, andelevated steady −burning red lights on each side. A
controlled stop bar is operated in conjunction with the
taxiway centerline lead −on lights which extend from
the stop bar toward the runway. Following the ATC
clearance to proceed, the stop bar is turned off and the
lead−on lights are turned on. The stop bar and lead −on
lights are automatically reset by a sensor or backup
timer.
CAUTION −
Pilots should never cross a red illuminated stop bar, even
if an ATC clearance has been given to proceed onto or
across the runway.
NOTE−
If after crossing a stop bar, the taxiway centerline lead −on
lights inadvertently extinguish, pilots should hold theirposition and contact ATC for further instructions.
AIM 10/12/17
2−2−1 Air Navigation and Obstruction LightingSection 2. Air Navigation and Obstruction Lighting
2−2−1. Aeronautical Light Beacons
a.An aeronautical light beacon is a visual
NA V AID displaying flashes of white and/or colored
light to indicate the location of an airport, a heliport,
a landmark, a certain point of a Federal airway inmountainous terrain, or an obstruction. The light used
may be a rotating beacon or one or more flashing
lights. The flashing lights may be supplemented bysteady burning lights of lesser intensity.
b.The color or color combination displayed by a
particular beacon and/or its auxiliary lights tell
whether the beacon is indicating a landing place,landmark, point of the Federal airways, or an
obstruction. Coded flashes of the auxiliary lights, if
employed, further identify the beacon site.
2−2−2. Code Beacons and Course Lights
a. Code Beacons. The code beacon, which can be
seen from all directions, is used to identify airports
and landmarks. The code beacon flashes the three or
four character airport identifier in InternationalMorse Code six to eight times per minute. Green
flashes are displayed for land airports while yellow
flashes indicate water airports.
b. Course Lights. The course light, which can be
seen clearly from only one direction, is used only with
rotating beacons of the Federal Airway System:
two course lights, back to back, direct coded flashing
beams of light in either direction along the course of
airway.
NOTE−
Airway beacons are remnants of the “lighted” airwayswhich antedated the present electronically equipped
federal airways system. Only a few of these beacons exist
today to mark airway segments in r emote mountain areas.
Flashes in Morse code identify the beacon site.
2−2−3. Obstruction Lights
a.Obstructions are marked/lighted to warn airmen
of their presence during daytime and nighttime
conditions. They may be marked/lighted in any of the
following combinations:1. Aviation Red Obstruction Lights. Flash-
ing aviation red beacons (20 to 40 flashes per minute)
and steady burning aviation red lights during
nighttime operation. A viation orange and white paint
is used for daytime marking.
2. Medium Intensity Flashing White
Obstruction Lights. Medium intensity flashing
white obstruction lights may be used during daytimeand twilight with automatically selected reduced
intensity for nighttime operation. When this system
is used on structures 500 feet (153m) AGL or less inheight, other methods of marking and lighting the
structure may be omitted. Aviation orange and white
paint is always required for daytime marking onstructures exceeding 500 feet (153m) AGL. This
system is not normally installed on structures less
than 200 feet (61m) AGL.
3. High Intensity White Obstruction Lights.
Flashing high intensity white lights during daytime
with reduced intensity for twilight and nighttimeoperation. When this type system is used, the marking
of structures with red obstruction lights and aviation
orange and white paint may be omitted.
4. Dual Lighting. A combination of flashing
aviation red beacons and steady burning aviation red
lights for nighttime operation and flashing high
intensity white lights for daytime operation. A viation
orange and white paint may be omitted.
5. Catenary Lighting. Lighted markers are
available for increased night conspicuity of high −
voltage (69KV or higher) transmission line catenarywires. Lighted markers provide conspicuity both day
and night.
b.Medium intensity omnidirectional flashing
white lighting system provides conspicuity both day
and night on catenary support structures. The unique
sequential/simultaneous flashing light system alertspilots of the associated catenary wires.
c.High intensity flashing white lights are being
used to identify some supporting structures ofoverhead transmission lines located across rivers,
chasms, gorges, etc. These lights flash in a middle,
top, lower light sequence at approximately 60 flashes
per minute. The top light is normally installed near
the top of the supporting structure, while the lowerlight indicates the approximate lower portion of the
AIM 10/12/17
2−2−2 Air Navigation and Obstruction Lightingwire span. The lights are beamed towards the
companion structure and identify the area of the wire
span.
d.High intensity flashing white lights are also
employed to identify tall structures, such as chimneysand towers, as obstructions to air navigation. The
lights provide a 360 degree coverage about the
structure at 40 flashes per minute and consist of from
one to seven levels of lights depending upon the
height of the structure. Where more than one level is
used the vertical banks flash simultaneously.
AIM 10/12/17
2−3−1 Airport Marking Aids and SignsSection 3. Airport Marking Aids and Signs
2−3−1. General
a.Airport pavement markings and signs provide
information that is useful to a pilot during takeoff,
landing, and taxiing.
b.Uniformity in airport markings and signs from
one airport to another enhances safety and improves
efficiency. Pilots are encouraged to work with the
operators of the airports they use to achieve the
marking and sign standards described in this section.
c.Pilots who encounter ineffective, incorrect, or
confusing markings or signs on an airport shouldmake the operator of the airport aware of the problem.
These situations may also be reported under the
Aviation Safety Reporting Program as described in
Paragraph 7 −6−1, Aviation Safety Reporting Pro-
gram. Pilots may also report these situations to the
FAA regional airports division.
d.The markings and signs described in this
section of the AIM reflect the current FAArecommended standards.
REFERENCE−
AC 150/5340 −1, Standards for Airport Markings.
AC 150/5340− 18, Standards for Airport Sign Systems.2−3−2. Airport Pavement Markings
a. General. For the purpose of this section, the
airport pavement markings have been grouped into
four areas:
1. Runway Markings.
2. Taxiway Markings.3. Holding Position Markings.4. Other Markings.
b. Marking Colors. Markings for runways are
white. Markings defining the landing area on a
heliport are also white except for hospital heliports
which use a red “H” on a white cross. Markings fortaxiways, areas not intended for use by aircraft
(closed and hazardous areas), and holding positions
(even if they are on a runway) are yellow.
2−3−3. Runway Markings
a. General. There are three types of markings for
runways: visual, nonprecision instrument, and
precision instrument. TBL 2 −3−1 identifies the
marking elements for each type of runway andTBL 2−3−2 identifies runway threshold markings.
TBL 2−3−1
Runway Marking Elements
Marking Element Visual RunwayNonprecision
Instrument
RunwayPrecision
Instrument
Runway
Designation X X X
Centerline X X X
Threshold X1X X
Aiming Point X2X X
Touchdown Zone X
Side Stripes X
1On runways used, or intended to be used, by international commercial transports.
2On runways 4,000 feet (1200 m) or longer used by jet aircraft.
AIM 10/12/17
2−3−2 Airport Marking Aids and SignsFIG 2− 3−1
Precision Instrument Runway Markings
b. Runway Designators. Runway numbers and
letters are determined from the approach direction.
The runway number is th e whole number nearest
one-tenth the magnetic azimuth of the centerline ofthe runway, measured clockwise from the magneticnorth. The letters, differentiate between left (L),
right (R), or center (C) parallel runways, as
applicable:
1.For two parallel runways “L” “R.”
2.For three parallel runways “L” “C” “R.”
c. Runway Centerline Marking. The runway
centerline identifies the center of the runway andprovides alignment guidance during takeoff and
landings. The centerline consists of a line of
uniformly spaced stripes and gaps.d. Runway Aiming Point Marking. The aiming
point marking serves as a visual aiming point for alanding aircraft. These two rectangular markings
consist of a broad white stripe located on each side of
the runway centerline and approximately 1,000 feetfrom the landing threshold, as shown in FIG 2− 3−1,
Precision Instrument Runway Markings.
e. Runway Touchdown Zone Markers. The
touchdown zone markings identify the touchdownzone for landing operations and are coded to provide
distance information in 500 feet (150m) increments.
These markings consist of groups of one, two, andthree rectangular bars symmetrically arranged in
pairs about the runway centerline, as shown in
FIG 2− 3−1. For runways having touchdown zone
markings on both ends, those pairs of markings which
extend to within 900 feet (270 m) of the midpoint
between the thresholds are eliminated.
AIM 10/12/17
2−3−3 Airport Marking Aids and SignsFIG 2− 3−2
Nonprecision Instrument Runway and Visual Runway Markings
20AIMING POINT
MARKING
THRESHOLD THRESHOLD
MARKINGSDESIGNATIONMARKINGPAVEMENT EDGE
AIMING POINTMARKING
PAVEMENT EDGEDESIGNATION MARKING
THRESHOLDNONPRECISION INSTRUMENT RUNWAY MARKINGS
VISUAL RUNWAY MARKINGS
f. Runway Side Stripe Marking. Runway side
stripes delineate the edges of the runway. They
provide a visual contrast between runway and the
abutting terrain or shoulders. Side stripes consist of
continuous white stripes located on each side of therunway as shown in FIG 2− 3−4.
g. Runway Shoulder Markings. Runway shoul-
der stripes may be used to supplement runway side
stripes to identify pavement areas contiguous to the
runway sides that are not intended for use by aircraft.
Runway shoulder stripes are yellow.
(See FIG 2− 3−5.)
h. Runway Threshold Markings. Runway
threshold markings come in two configurations. They
either consist of eight longitudinal stripes of uniformdimensions disposed symmetrically about therunway centerline (as shown in FIG 2− 3−1) or the
number of stripes is related to the runway width asindicated in TBL 2 −3−2. A threshold marking helps
identify the beginning of the runway that is available
for landing. In some instances, the landing thresholdmay be relocated or displaced.
TBL 2−3−2
Number of Runway Threshold Stripes
Runway Width Number of Stripes
60 feet (18 m) 4
75 feet (23 m) 6
100 feet (30 m) 8
150 feet (45 m) 12
200 feet (60 m) 16
AIM 10/12/17
2−3−4 Airport Marking Aids and Signs1. Relocation of a Threshold. Sometimes
construction, maintenance, or other activities require
the threshold to be relocated towards the rollout end
of the runway. (See FIG 2 −3−3.) When a threshold is
relocated, it closes not only a set portion of the
approach end of a runway, but also shortens the length
of the opposite direction runway. In these cases, aNOTAM should be issued by the airport operatoridentifying the portion of the runway that is closed
(for example, 10/28 W 900 CLSD). Because the
duration of the relocation can vary from a few hoursto several months, methods identifying the new
threshold may vary. One common practice is to use a
ten feet wide white threshold bar across the width of
the runway. Although the runway lights in the area
between the old threshold and new threshold will not
be illuminated, the runway markings in this area may
or may not be obliterated, removed, or covered.
2. Displaced Threshold. A displaced thresh-
old is a threshold located at a point on the runwayother than the designated beginning of the runway.
Displacement of a threshold reduces the length of
runway available for landings. The portion of runway
behind a displaced threshold is available for takeoffs
in either direction and landings from the oppositedirection. A ten feet wide white threshold bar islocated across the width of the runway at the
displaced threshold. White arrows are located along
the centerline in the area between the beginning of the
runway and displaced threshold. White arrow heads
are located across the width of the runway just priorto the threshold bar, as shown in FIG 2− 3−4.
NOTE−
Airport operator. When reporting the relocation ordisplacement of a threshold, the airport operator shouldavoid language which confuses the two.
i. Demarcation Bar. A demarcation bar delin-
eates a runway with a displaced threshold from a blast
pad, stopway, or taxiway that precedes the runway. A
demarcation bar is 3 feet (1m) wide and yellow, since
it is not located on the runway, as shown inFIG 2− 3−6.
1. Chevrons. These markings are used to show
pavement areas aligned with the runway that areunusable for landing, takeoff, and taxiing. Chevronsare yellow. (See FIG 2− 3−7.)
j. Runway Threshold Bar. A threshold bar
delineates the beginning of the runway that isavailable for landing when the threshold has beenrelocated or displaced. A threshold bar is 10 feet (3m)
in width and extends across the width of the runway,
as shown in FIG 2− 3−4.
AIM 10/12/17
2−3−5 Airport Marking Aids and SignsFIG 2− 3−3
Relocation of a Threshold with Markings for Taxiway Aligned with Runway
AIM 10/12/17
2−3−6 Airport Marking Aids and SignsFIG 2− 3−4
Displaced Threshold Markings
AIM 10/12/17
2−3−7 Airport Marking Aids and SignsFIG 2− 3−5
Runway Shoulder Markings
RUNWAY THRESHOLDMIDPOINT OF
RUNWAYSHOULDER SHOULDER RUNWAY
45° 45°
45°45°
2−3−4. Taxiway Markings
a. General. All taxiways should have centerline
markings and runway holding position markings
whenever they intersect a runway. Taxiway edgemarkings are present whenever there is a need to
separate the taxiway from a pavement that is not
intended for aircraft use or to delineate the edge of the
taxiway. Taxiways may also have shoulder markings
and holding position markings for InstrumentLanding System (ILS) critical areas and taxiway/taxiway intersection markings.
REFERENCE−
AIM Paragraph 2 −3−5 , Holding Position Markings
b. Taxiway Centerline.
1. Normal Centerline. The taxiway centerline
is a single continuous yellow line, 6 inches (15 cm) to
12 inches (30 cm) in width. This provides a visual cue
to permit taxiing along a designated path. Ideally, the
aircraft should be kept centered over this line duringtaxi. However, being centered on the taxiway
centerline does not guarantee wingtip clearance with
other aircraft or other objects.2. Enhanced Centerline. At some airports,
mostly the larger commercial service airports, an
enhanced taxiway centerline will be used. The
enhanced taxiway centerline marking consists of a
parallel line of yellow dashes on either side of thenormal taxiway centerline. The taxiway centerlines
are enhanced for a maximum of 150 feet prior to a
runway holding position marking. The purpose ofthis enhancement is to warn the pilot that he/she is
approaching a runway holding position marking and
should prepare to stop unless he/she has been cleared
onto or across the runway by ATC. (See FIG 2 −3−8.)
c. Taxiway Edge Markings. Taxiway edge
markings are used to define the edge of the taxiway.They are primarily used when the taxiway edge does
not correspond with the edge of the pavement. There
are two types of markings depending upon whether
the aircraft is supposed to cross the taxiway edge:
1. Continuous Markings. These consist of a
continuous double yellow line, with each line beingat least 6 inches (15 cm) in width spaced 6 inches
(15 cm) apart. They are used to define the taxiwayedge from the shoulder or some other abutting paved
surface not intended for use by aircraft.
2. Dashed Markings. These markings are
used when there is an operational need to define theedge of a taxiway or taxilane on a paved surfacewhere the adjoining pavement to the taxiway edge is
intended for use by aircraft (for example, an apron).
Dashed taxiway edge markings consist of a brokendouble yellow line, with each line being at least 6
inches (15 cm) in width, spaced 6 inches (15 cm)
apart (edge to edge). These lines are 15 feet (4.5 m)in length with 25 foot (7.5 m) gaps. (See FIG 2 −3−9.)
d. Taxi Shoulder Markings. Taxiways, holding
bays, and aprons are sometimes provided with paved
shoulders to prevent blast and water erosion.Although shoulders may have the appearance of fullstrength pavement, they are not intended for use by
aircraft and may be unable to support an aircraft.
Usually the taxiway edge marking will define thisarea. Where conditions exist such as islands or
taxiway curves that may cause confusion as to which
side of the edge stripe is for use by aircraft, taxiway
shoulder markings may be used to indicate the
pavement is unusable. Taxiway shoulder markings
are yellow. (See FIG 2− 3−10.)
AIM 10/12/17
2−3−8 Airport Marking Aids and SignsFIG 2− 3−6
Markings for Blast Pad or Stopway or Taxiway Preceding a Displaced Threshold
AIM 10/12/17
2−3−9 Airport Marking Aids and SignsFIG 2− 3−7
Markings for Blast Pads and Stopways
AIM 10/12/17
2−3−10 Airport Marking Aids and SignsFIG 2− 3−8
Enhanced Taxiway Centerline
FIG 2− 3−9
Dashed Markings
DOUBLE
YELLOWLINES
TAXIWAY EDGEMARKINGSCONTINUOUSTAXIWAY EDGEMARKINGSDASHED
e. Surface Painted Taxiway Direction
Signs. Surface painted taxiway direction signs have
a yellow background with a black inscription, and are
provided when it is not possible to provide taxiway
direction signs at intersections, or when necessary to
supplement such signs. These markings are located
adjacent to the centerline with signs indicating turns
to the left being on the left side of the taxiwaycenterline, and signs indicating turns to the right
being on the right side of the centerline. (See
FIG 2− 3−11.)
FIG 2− 3−10
Taxi Shoulder Markings
YELLOW STRIPESPAVEMENT EDGE
TAXIWAY EDGE
MARKINGSRUNWAY
f. Surface Painted Location Signs. Surface
painted location signs have a black background with
a yellow inscription. When necessary, these markings
are used to supplement location signs located along
side the taxiway and assist the pilot in confirming the
designation of the taxiway on which the aircraft is
located. These markings are located on the right side
of the centerline. (See FIG 2− 3−11.)
g. Geographic Position Markings. These mark-
ings are located at points along low visibility taxiroutes designated in the airport’s Surface Movement
Guidance Control System (SMGCS) plan. They areused to identify the location of taxiing aircraft during
low visibility operations. Low visibility operationsare those that occur when the runway visiblerange (RVR) is below 1200 feet (360m). They are
positioned to the left of the taxiway centerline in the
direction of taxiing. (See FIG 2 −3−12.) The
geographic position marking is a circle comprised of
an outer black ring contiguous to a white ring with a
pink circle in the middle. When installed on asphaltor other dark-colored pavements, the white ring and
the black ring are reversed (i.e., the white ring
becomes the outer ring and the black ring becomes the
inner ring). It is designated with either a number or a
number and letter. The number corresponds to theconsecutive position of the marking on the route.
AIM 10/12/17
2−3−11 Airport Marking Aids and SignsFIG 2− 3−11
Surface Painted Signs
AIM 10/12/17
2−3−12 Airport Marking Aids and Signs2−3−5. Holding Position Markings
a. Runway Holding Position Markings. For
runways, these markings indicate where aircraft
MUST STOP when approaching a runway. They
consist of four yellow lines, two solid and two dashed,
spaced six or twelve inches apart, and extending
across the width of the taxiway or runway. The solidlines are always on the side where the aircraft must
hold. There are three locations where runway holding
position markings are encountered.
1. Runway Holding Position Markings on
Taxiways. These markings identify the locations on
a taxiway where aircraft MUST STOP when a
clearance has not been issued to proceed onto the
runway. Generally, runway holding position mark-ings also identify the boundary of the runway safetyarea (RSA) for aircraft exiting the runway. Runway
holding position markings are shown in FIG 2− 3−13
and FIG 2− 3−16. When instructed by ATC, “ Hold
short of Runway XX ,” the pilot MUST STOP so that
no part of the aircraft extends beyond the runwayholding position marking. When approaching
runways at airports with an operating control tower,
pilots must not cross the runway holding position
marking without ATC clearance. Pilots approaching
runways at airports without an operating control
tower must ensure adequate separation from other
aircraft, vehicles, and pedestrians prior to crossing
the holding position markings. An aircraft exiting a
runway is not clear of the runway until all parts of the
aircraft have crossed the applicable holding position
marking.
NOTE−
Runway holding position markings identify the beginning
of an RSA, and a pilot MUST STOP to get clearance before
crossing (at airports with operating control towers).
REFERENCE−
AIM, Paragraph 4 −3−20 , Exiting the Runway After Landing
2. Runway Holding Position Markings on
Runways. These markings identify the locations on
runways where aircraft MUST STOP. These
markings are located on runways used by ATC for
Land And Hold Short Operations (for example, see
FIG 4− 3−8) and Taxiing operations. For taxiing
operations, the pilot MUST STOP prior to the holding
position markings unless explicitly authorized to
cross by A TC. A sign with a white inscription on a red
background is located adjacent to these holding
position markings. (See FIG 2− 3−14.) The holding
position markings are placed on runways prior to the
intersection with another runway, or some designatedpoint. Pilots receiving and accepting instructions
“Cleared to land Runway XX, hold short of Runway
YY” from ATC must either exit Runway XX prior to
the holding position markings, or stop at the holding
position markings prior to Runway YY . Otherwise,
pilots are authorized to use the entire landing lengthof the runway and disregard the holding position
markings.
3. Holding Position Markings on Taxiways
Located in Runway Approach Areas. These
markings are used at some airports where it isnecessary to hold an aircraft on a taxiway located in
the approach or departure area of a runway so that the
aircraft does not interfere with the operations on that
runway. This marking is collocated with the runwayapproach area holding position sign. When specifi-
cally instructed by ATC, “ Hold short of Runway XX
approach area, ” the pilot MUST STOP so that no part
of the aircraft extends beyond the holding positionmarking. (See Subparagraph 2 −3−8b2, Runway
Approach Area Holding Position Sign, and
FIG 2− 3−15.)
b. Holding Position Markings for Instrument
Landing System (ILS). Holding position markings
for ILS critical areas consist of two yellow solid lines
spaced two feet apart connected by pairs of solid lines
spaced ten feet apart extending across the width of the
taxiway as shown. (See FIG 2 −3−16.) A sign with an
inscription in white on a red background is located
adjacent to these hold position markings. When
instructed by ATC to hold short of the ILS critical
area, pilots MUST STOP so that no part of the aircraft
extends beyond the holding position marking. Whenapproaching the holding position marking, pilotsmust not cross the marking without ATC clearance.
The ILS critical area is not clear until all parts of the
aircraft have crossed the applicable holding positionmarking.
REFERENCE−
AIM, Paragraph 1 −1−9 , Instrument Landing System (ILS)
c. Holding Position Markings for Intersecting
Taxiways Holding position markings for intersect-
ing taxiways consist of a single dashed line extending
across the width of the taxiway as shown. (See
FIG 2− 3−17.) They are located on taxiways where
ATC holds aircraft short of a taxiway intersection.
When instructed by ATC, “Hold short of Taxiway
XX,” the pilot MUST STOP so that no part of the
aircraft extends beyond the holding position marking.
When the marking is not present, the pilot MUST
AIM 10/12/17
2−3−13 Airport Marking Aids and SignsSTOP the aircraft at a point which provides adequate
clearance from an aircraft on the intersecting taxiway.
d. Surface Painted Holding Position Signs.
Surface painted holding position signs have a red
background with a white inscription and supplementthe signs located at the holding position. This type of
marking is normally used where the width of the
holding position on the taxiway is greater than
200 feet (60 m). It is located to the left side of the
taxiway centerline on the holding side and prior to the
holding position marking. (See FIG 2− 3−11.)
FIG 2− 3−12
Geographic Position Markings
FIG 2− 3−13
Runway Holding Position Markings on Taxiway
RUNWAY
TAXIWAY
EXAMPLE OF HOLDING POSITION MARKINGS
EXTENDED ACROSS HOLDING BAYHOLDING
BAY15
TAXIWAY/RUNWAYHOLDING POSITIONMARKINGS
AIM 10/12/17
2−3−14 Airport Marking Aids and SignsFIG 2− 3−14
Runway Holding Position Markings on Runways
AIM 10/12/17
2−3−15 Airport Marking Aids and SignsFIG 2− 3−15
Taxiways Located in Runway Approach Area
AIM 10/12/17
2−3−16 Airport Marking Aids and SignsFIG 2− 3−16
Holding Position Markings: ILS Critical Area
DETAIL 2DETAIL 1RUNWAY HOLDING
POSITION MARKINGS,YELLOW, SEEDETAIL 1
ILS HOLDINGPOSITION MARKINGS,YELLOW, SEEDETAIL 2
ILS CRITICALAREA
2−3−6. Other Markings
a. Vehicle Roadway Markings. The vehicle
roadway markings are used when necessary to define
a pathway for vehicle operations on or crossing areas
that are also intended for aircraft. These markings
consist of a white solid line to delineate each edge of
the roadway and a dashed line to separate lanes within
the edges of the roadway. In lieu of the solid lines,
zipper markings may be used to delineate the edgesof the vehicle roadway . (See FIG 2− 3−18.) Details of
the zipper markings are shown in FIG 2− 3−19.
b. VOR Receiver Checkpoint Markings. The
VOR receiver checkpoint marking allows the pilot to
check aircraft instruments with navigational aid
signals. It consists of a painted circle with an arrow inthe middle; the arrow is aligned in the direction of the
checkpoint azimuth. This marking, and an associated
sign, is located on the airport apron or taxiway at apoint selected for easy access by aircraft but where
other airport traffic is not to be unduly obstructed.(See FIG 2− 3−20.)
NOTE−
The associated sign contains the VOR station identification
letter and course selected (published) for the check, thewords “VOR check course,” and DME data (when
applicable). The color of the letters and numerals are black
on a yellow background.
EXAMPLE−
DCA 176− 356
VOR check courseDME XXX
AIM 10/12/17
2−3−17 Airport Marking Aids and SignsFIG 2− 3−17
Holding Position Markings: Taxiway/Taxiway Intersections
TAXIWAY HOLDING
POSITION MARKINGS,YELLOW, SEEDETAIL 1
DETAIL 1
FIG 2− 3−18
Vehicle Roadway Markings
AIM 10/12/17
2−3−18 Airport Marking Aids and SignsFIG 2− 3−19
Roadway Edge Stripes, White, Zipper Style
c. Nonmovement Area Boundary Markings.
These markings delineate the movement area
(i.e., area under ATC). These markings are yellow
and located on the boundary between the movement
and nonmovement area. The nonmovement areaboundary markings consist of two yellow lines (one
solid and one dashed) 6 inches (15cm) in width. The
solid line is located on the nonmovement area side,while the dashed yellow line is located on the
movement area side. The nonmovement boundary
marking area is shown in FIG 2− 3−21.FIG 2− 3−20
Ground Receiver Checkpoint Markings
1. WHITE
2. YELLOW3. YELLOW ARROW ALIGNED TOWARD THE FACILITY4. INTERIOR OF CIRCLE BLACK (CONCRETE SURFACE ONLY)5. CIRCLE MAY BE BORDERED ON INSIDE AND OUTSIDE WITH
6" BLACK BAND IF NECESSARY FOR CONTRAST5
FIG 2− 3−21
Nonmovement Area Boundary Markings
BOTH LINES
ARE YELLOW
SOLID LINE ONNONMOVEMENTSIDEDASHED LINE ONMOVEMENT SIDE
FIG 2− 3−22
Closed or Temporarily Closed Runway
and Taxiway Markings
2X
d. Marking and Lighting of Permanently
Closed Runways and Taxiways. For runways and
taxiways which are permanently closed, the lighting
circuits will be disconnected. The runway threshold,
runway designation, and touchdown markings areobliterated and yellow crosses are placed at each end
of the runway and at 1,000 foot intervals. (See FIG 2− 3−22.)
AIM 10/12/17
2−3−19 Airport Marking Aids and SignsFIG 2− 3−23
Helicopter Landing Areas
e. Temporarily Closed R unways and T axiways.
To provide a visual indication to pilots that a runway
is temporarily closed, crosses are placed on the
runway only at each end of the runway. The crosses
are yellow in color. (See FIG 2− 3−22.)
1.A raised lighted yellow cross may be placed
on each runway end in lieu of the markings described
in Subparagraph e,Temporarily Closed Runways and
Taxiways, to indicate the runway is closed.
2.A visual indication may not be present
depending on the reason for the closure, duration of
the closure, airfield configuration, and the existence
and the hours of operation of an airport traffic control
tower. Pilots should check NOTAMs and the
Automated Terminal Information System (ATIS) for
local runway and taxiway closure information.
3.Temporarily closed taxiways are usually
treated as hazardous areas, in which no part of anaircraft may enter, and are blocked with barricades.
However, as an alternative, a yellow cross may beinstalled at each entrance to the taxiway.f. Helicopter Landing Areas. The markings
illustrated in FIG 2− 3−23 are used to identify the
landing and takeoff area at a public use heliport and
hospital heliport. The letter “H” in the markings is
oriented to align with the intended direction ofapproach. FIG 2− 3−23 also depicts the markings for
a closed airport.
2−3−7. Airport Signs
There are six types of signs installed on airfields:
mandatory instruction signs, location signs, direction
signs, destination signs, information signs, and
runway distance remaining signs. The characteristics
and use of these signs are discussed in Para-graph 2−3−8, Mandatory Instruction Signs, through
Paragraph 2 −3−13, Runway Distance Remaining
Signs.
REFERENCE−
AC150/5340 −18, Standards for Airport Sign Systems for Detailed
Information on Airport Signs.
AIM 10/12/17
2−3−20 Airport Marking Aids and SignsFIG 2− 3−24
Runway Holding Position Sign
FIG 2− 3−25
Holding Position Sign at Beginning of Takeoff Runway
2−3−8. Mandatory Instruction Signs
a.These signs have a red background with a white
inscription and are used to denote:
1.An entrance to a runway or critical area; and
2.Areas where an aircraft is prohibited from
entering.
b. Typical mandatory signs and applications
are:
1. Runway Holding Position Sign. This sign
is located at the holding position on taxiways that
intersect a runway or on runways that intersect otherrunways. The inscription on the sign contains thedesignation of the intersecting runway, as shown in
FIG 2− 3−24. The runway numbers on the sign are
arranged to correspond to the respective runwaythreshold. For example, “15 −33” indicates that the
threshold for Runway 15 is to the left and the
threshold for Runway 33 is to the right.
(a)On taxiways that intersect the beginning
of the takeoff runway, only the designation of the
takeoff runway may appear on the sign (as shown inFIG 2− 3−25), while all other signs will have the
designation of both runway directions.
AIM 10/12/17
2−3−21 Airport Marking Aids and SignsFIG 2− 3−26
Holding Position Sign for a Taxiway that Intersects the Intersection of Two Runways
FIG 2− 3−27
Holding Position Sign for a Runway Approach Area
(b)If the sign is located on a taxiway that
intersects the intersection of two runways, the
designations for both runways will be shown on the
sign along with arrows showing the approximate
alignment of each runway , as shown in FIG 2− 3−26.
In addition to showing the approximate runway
alignment, the arrow indicates the direction to the
threshold of the runway whose designation isimmediately next to the arrow.
(c)A runway holding position sign on a
taxiway will be installed adjacent to holding positionmarkings on the taxiway pavement. On runways,
holding position markings will be located only on the
runway pavement adjacent to the sign, if the runway
is normally used by ATC for “Land, Hold Short”
operations or as a taxiway. The holding positionmarkings are described in Paragraph 2 −3−5, Holding
Position Markings.
2. Runway Approach Area Holding Position
Sign. At some airports, it is necessary to hold an
aircraft on a taxiway located in the approach or
departure area for a runway so that the aircraft does
not interfere with operations on that runway. In these
situations, a sign with the designation of the approach
end of the runway followed by a “dash” ( −) and letters
“APCH” will be located at the holding position on the
taxiway. Holding position markings in accordancewith Paragraph 2 −3−5, Holding Position Markings,
will be located on the taxiway pavement. An example
of this sign is shown in FIG 2 −3−27. In this example,
the sign may protect the approach to Runway 15
and/or the departure for Runway 33.
AIM 10/12/17
2−3−22 Airport Marking Aids and SignsFIG 2− 3−28
Holding Position Sign for ILS Critical Area
FIG 2− 3−29
Sign Prohibiting Aircraft Entry into an Area
3. ILS Critical Area Holding Position
Sign. At some airports, when the instrument landing
system is being used, it is necessary to hold an aircraft
on a taxiway at a location other than the holding
position described in Paragraph 2 −3−5, Holding
Position Markings. In these situations, the holding
position sign for these operations will have the
inscription “ILS” and be located adjacent to theholding position marking on the taxiway described in
paragraph 2 −3−5. An example of this sign is shown
in FIG 2− 3−28.4. No Entry Sign. This sign, shown in
FIG 2− 3−29, prohibits an aircraft from entering an
area. Typically, this sign would be located on a
taxiway intended to be used in only one direction or
at the intersection of vehicle roadways with runways,taxiways, or aprons where the roadway may be
mistaken as a taxiway or other aircraft movement
surface.
NOTE−
Holding position signs provide the pilot with a visual cueas to the location of the holding position marking.
REFERENCE−
AIM Paragraph 2 −3−5, Holding Position Markings
AIM 10/12/17
2−3−23 Airport Marking Aids and SignsFIG 2− 3−30
Taxiway Location Sign
FIG 2− 3−31
Taxiway Location Sign Collocated with Runway Holding Position Sign
2−3−9. Location Signs
a.Location signs are used to identify either a
taxiway or runway on which the aircraft is located.
Other location signs provide a visual cue to pilots to
assist them in determining when they have exited an
area. The various location signs are described below.1. Taxiway Location Sign. This sign has a
black background with a yellow inscription andyellow border, as shown in FIG 2− 3−30. The
inscription is the designation of the taxiway on whichthe aircraft is located. These signs are installed alongtaxiways either by themselves or in conjunction with
direction signs or runway holding position signs.
(See FIG 2− 3−35 and FIG 2− 3−31.)
AIM 10/12/17
2−3−24 Airport Marking Aids and SignsFIG 2− 3−32
Runway Location Sign
FIG 2− 3−33
Runway Boundary Sign
2. Runway Location Sign. This sign has a
black background with a yellow inscription and
yellow border, as shown in FIG 2− 3−32. The
inscription is the designation of the runway on whichthe aircraft is located. These signs are intended tocomplement the information available to pilots
through their magnetic compass and typically are
installed where the proximity of two or more runways
to one another could cause pilots to be confused as to
which runway they are on.3. Runway Boundary Sign. This sign has a
yellow background with a black inscription with a
graphic depicting the pavement holding position
marking, as shown in FIG 2− 3−33. This sign, which
faces the runway and is visible to the pilot exiting the
runway, is located adjacent to the holding positionmarking on the pavement. The sign is intended to
provide pilots with another visual cue which they can
use as a guide in deciding when they are “clear of the
runway.”
AIM 10/12/17
2−3−25 Airport Marking Aids and SignsFIG 2− 3−34
ILS Critical Area Boundary Sign
4. ILS Critical Area Boundary Sign. This
sign has a yellow background with a black inscription
with a graphic depicting the ILS pavement holding
position marking as shown in FIG 2− 3−34. This sign
is located adjacent to the ILS holding position
marking on the pavement and can be seen by pilots
leaving the critical area. The sign is intended to
provide pilots with another visual cue which they can
use as a guide in deciding when they are “clear of the
ILS critical area.”
2−3−10. Direction Signs
a.Direction signs have a yellow background with
a black inscription. The inscription identifies the
designation(s) of the intersecting taxiway(s) leading
out of the intersection that a pilot would normally be
expected to turn onto or hold short of. Eachdesignation is accompanied by an arrow indicating
the direction of the turn.
b.Except as noted in subparagraph e, each
taxiway designation shown on the sign is accompa-
nied by only one arrow. When more than one taxiway
designation is shown on the sign, each designation
and its associated arrow is separated from the othertaxiway designations by either a vertical message
divider or a taxiway location sign as shown in
FIG 2− 3−35.
c.Direction signs are normally located on the left
prior to the intersection. When used on a runway toindicate an exit, the sign is located on the same side
of the runway as the exit. FIG 2− 3−36 shows a
direction sign used to indicate a runway exit.
d.The taxiway designations and their associated
arrows on the sign are arranged clockwise starting
from the first taxiway on the pilot’s left. (See FIG 2− 3−35.)
e.If a location sign is located with the direction
signs, it is placed so that the designations for all turnsto the left will be to the left of the location sign; the
designations for continuing straight ahead or for all
turns to the right would be located to the right of thelocation sign. (See FIG 2− 3−35.)
f.When the intersection is comprised of only one
crossing taxiway, it is permissible to have two arrows
associated with the crossing taxiway, as shown in
FIG 2− 3−37. In this case, the location sign is located
to the left of the direction sign.
AIM 10/12/17
2−3−26 Airport Marking Aids and SignsFIG 2− 3−35
Direction Sign Array with Location Sign on Far Side of Intersection
FIG 2− 3−36
Direction Sign for Runway Exit
AIM 10/12/17
2−3−27 Airport Marking Aids and SignsFIG 2− 3−37
Direction Sign Array for Simple Intersection
AIM 10/12/17
2−3−28 Airport Marking Aids and SignsFIG 2− 3−38
Destination Sign for Military Area
FIG 2− 3−39
Destination Sign for Common Taxiing Route to Two Runways
2−3−11. Destination Signs
a.Destination signs also have a yellow back-
ground with a black inscription indicating a
destination on the airport. These signs always have an
arrow showing the direction of the taxiing route tothat destination. FIG 2 −3−38 is an example of a
typical destination sign. When the arrow on the
destination sign indicates a turn, the sign is located
prior to the intersection.
b.Destinations commonly shown on these types
of signs include runways, aprons, terminals, military
areas, civil aviation areas, cargo areas, internationalareas, and fixed base operators. An abbreviation may
be used as the inscription on the sign for some of these
destinations.
c.When the inscription for two or more
destinations having a common taxiing route areplaced on a sign, the destinations are separated by a
“dot” ( /C0068) and one arrow would be used, as shown in
FIG 2− 3−39. When the inscription on a sign contains
two or more destinations having different taxiing
routes, each destination will be accompanied by an
arrow and will be separated from the otherdestinations on the sign with a vertical black message
divider, as shown in FIG 2− 3−40.
AIM 10/12/17
2−3−29 Airport Marking Aids and SignsFIG 2− 3−40
Destination Sign for Different Taxiing Routes to Two Runways
2−3−12. Information Signs
Information signs have a yellow background with a
black inscription. They are used to provide the pilot
with information on such things as areas that cannotbe seen from the control tower, applicable radio
frequencies, and noise abatement procedures. The
airport operator determines the need, size, and
location for these signs.
2−3−13. Runway Distance Remaining Signs
Runway distance remaining signs have a black
background with a white numeral inscription and
may be installed along one or both side(s) of therunway. The number on the signs indicates the
distance (in thousands of feet) of landing runway
remaining. The last sign (i.e., the sign with thenumeral “1”) will be located at least 950 feet from the
runway end. FIG 2 −3−41 shows an example of a
runway distance remaining sign.FIG 2− 3−41
Runway Distance Remaining Sign Indicating
3,000 feet of Runway Remaining
AIM 10/12/17
2−3−30 Airport Marking Aids and Signs2−3−14. Aircraft Arresting Systems
a.Certain airports are equipped with a means of
rapidly stopping military aircraft on a runway. This
equipment, normally referred to as EMERGENCY
ARRESTING GEAR, generally consists of pendant
cables supported over the runway surface by rubber
“donuts.” Although most devices are located in the
overrun areas, a few of these arresting systems havecables stretched over the operational areas near the
ends of a runway.
b.Arresting cables which cross over a runway
require special markings on the runway to identify
the cable location. These markings consist of 10 feetdiameter solid circles painted “identification yel-
low,” 30 feet on center, perpendicular to the runway
centerline across the entire runway width. Additional
details are contained in AC 150/5220 −9, Aircraft
Arresting Systems for Joint Civil/Military Airports.NOTE−
Aircraft operations on the runway are not restricted by the
installation of aircraft arresting devices.
c. Engineered Materials Arresting Systems
(EMAS) . EMAS, which is constructed of high
energy−absorbing materials of selected strength, is
located in the safety area beyond the end of the
runway. EMAS will be marked with yellow chevrons.
EMAS is designed to crush under the weight of
commercial aircraft and will exert deceleration forces
on the landing gear. These systems do not affect thenormal landing and takeoff of airplanes. More
information concerning EMAS is in AC150/5220−22, Engineered Materials Arresting Sys-
tems (EMAS) for Aircraft Overruns.
NOTE−
EMAS may be located as close as 35 feet beyond the end of
the runway. Aircraft and ground vehicles should never taxior drive across the EMAS or beyond the end of the runway
if EMAS is present.
FIG 2− 3−42
Engineered Materials Arresting System (EMAS)
AIM 10/12/17
2−3−31 Airport Marking Aids and Signs2−3−15. Security Identifications Display
Area (Airport Ramp Area)
a.Security Identification Display Areas (SIDA)
are limited access areas that require a badge issued in
accordance with procedures in CFR 49 Part 1542.Movement through or into these areas is prohibited
without proper identification being displayed. If you
are unsure of the location of a SIDA, contact theairport authority for additional information. Airports
that have a SIDA must have the followinginformation available:
1.A description and map detailing boundaries
and pertinent features;2.Measures used to perform the access control
functions required under CFR 49 Part1542.201(b)(1);
3.Procedures to control movement within the
secured area, including identification media required
under CFR 49 Part 1542.201(b)(3); and
4.A description of the notification signs
required under CFR 49 Part 1542.201(b)(6).
b.Pilots or passengers without proper identifica-
tion that are observed entering a SIDA (ramp area)
may be reported to TSA or airport security. Pilots areadvised to brief passengers accordingly.
AIM 10/12/17
3−1−1 GeneralChapter 3. Airspace
Section 1. General
3−1−1. General
a.There are two categories of airspace or airspace
areas:
1.Regulatory (Class A, B, C, D and E airspace
areas, restricted and prohibited areas); and
2.Nonregulatory (military operations areas
(MOAs), warning areas, alert areas, and controlled
firing areas).
NOTE−
Additional information on special use airspace (pr ohibited
areas, restricted areas, warning areas, MOAs, alert areasand controlled firing areas) may be found in Chapter 3,
Airspace, Section 4, Special Use Airspace, para-
graphs 3−4−1 through 3 −4−7.
b.Within these two categories, there are four
types:
1.Controlled,
2.Uncontrolled,
3.Special use, and
4.Other airspace.
c.The categories and types of airspace are dictated
by:
1.The complexity or density of aircraft
movements,
2.The nature of the operations conducted
within the airspace,
3.The level of safety required, and
4.The national and public interest.
d.It is important that pilots be familiar with the
operational requirements for each of the various types
or classes of airspace. Subsequent sections will cover
each class in sufficient detail to facilitateunderstanding.3−1−2. General Dimensions of Airspace
Segments
Refer to Code of Federal Regulations (CFRs) for
specific dimensions, exceptions, geographical areas
covered, exclusions, specific transponder or equip-
ment requirements, and flight operations.
3−1−3. Hierarchy of Overlapping Airspace
Designations
a.When overlapping airspace designations apply
to the same airspace, the operating rules associated
with the more restrictive airspace designation apply.
b.For the purpose of clarification:
1.Class A airspace is more restrictive than
Class B, Class C, Class D, Class E, or Class Gairspace;
2.Class B airspace is more restrictive than
Class C, Class D, Class E, or Class G airspace;
3.Class C airspace is more restrictive than
Class D, Class E, or Class G airspace;
4.Class D airspace is more restrictive than
Class E or Class G airspace; and
5.Class E is more restrictive than Class G
airspace.
3−1−4. Basic VFR Weather Minimums
a.No person may operate an aircraft under basic
VFR when the flight visibility is less, or at a distancefrom clouds that is less, than that prescribed for the
corresponding altitude and class of airspace.
(See TBL 3 −1−1.)
NOTE−
Student pilots must comply with 14 CFR Section 61.89(a)(6) and (7).
b.Except as provided in 14 CFR Section 91.157,
Special VFR Weather Minimums, no person may
operate an aircraft beneath the ceiling under VFRwithin the lateral boundaries of controlled airspace
designated to the surface for an airport when the
ceiling is less than 1,000 feet. (See 14 CFRSection 91.155(c).)
AIM 10/12/17
3−1−2 GeneralTBL 3−1−1
Basic VFR Weather Minimums
Airspace Flight Visibility Distance from Clouds
Class A ........................................ Not Applicable Not Applicable
Class B ........................................ 3 statute miles Clear of Clouds
Class C ........................................ 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
Class D ........................................ 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
Class E
Less than 10,000 feet MSL ........................ 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
At or above 10,000 feet MSL ...................... 5 statute miles 1,000 feet below
1,000 feet above
1 statute mile horizontal
Class G
1,200 feet or less above the surface (regardless of MSL
altitude).
Day, except as provided in section 91.155(b) .......... 1 statute mile Clear of clouds
Night, except as provided in section 91.155(b) ......... 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
More than 1,200 feet above the surface but less than
10,000 feet MSL.
D a y........................................... 1 statute mile 500 feet below1,000 feet above
2,000 feet horizontal
Night ......................................... 3 statute miles 500 feet below
1,000 feet above
2,000 feet horizontal
More than 1,200 feet above the surface and at or above
10,000 feet MSL. ................................5 statute miles 1,000 feet below
1,000 feet above
1 statute mile horizontal
3−1−5. VFR Cruising Altitudes and Flight Levels
(See TBL 3 −1−2.)
TBL 3−1−2
VFR Cruising Altitudes and Flight Levels
If your magnetic course
(ground track) is:And you are more than 3,000 feet above the
surface but below 18,000 feet MSL, fly:And you are above 18,000 feet
MSL to FL 290, fly:
0/C0005 to 179/C0005................ Odd thousands MSL, plus 500 feet
(3,500; 5,500; 7,500, etc.)Odd Flight Levels plus 500 feet(FL 195; FL 215; FL 235, etc.)
180/C0005 to 359/C0005.............. Even thousands MSL, plus 500 feet (4,500; 6,500; 8,500, etc.) Even Flight Levels plus 500 feet(FL 185; FL 205; FL 225, etc.)
AIM 10/12/17
3−2−1 Controlled AirspaceSection 2. Controlled Airspace
3−2−1. General
a. Controlled Airspace. A generic term that
covers the different classification of airspace
(Class A, Class B, Class C, Class D, and Class Eairspace) and defined dimensions within which air
traffic control service is provided to IFR flights and
to VFR flights in accordance with the airspaceclassification. (See FIG 3−2−1.)
b. IFR Requirements. IFR operations in any
class of controlled airspace requires that a pilot must
file an IFR flight plan and receive an appropriate ATC
clearance.
c. IFR Separation. Standard IFR separation is
provided to all aircraft operating under IFR in
controlled airspace.
d. VFR Requirements. It is the responsibility of
the pilot to ensure that ATC clearance or radio
communication requirements are met prior to entryinto Class B, Class C, or Class D airspace. The pilot
retains this responsibility when receiving ATC radar
advisories. (See 14 CFR Part 91.)
e. Traffic Advisories. Traffic advisories will be
provided to all aircraft as the controller’s work
situation permits.
f. Safety Alerts. Safety Alerts are mandatory
services and are provided to ALL aircraft. There are
two types of Safety Alerts:
1. Terrain/Obstruction Alert. A Terrain/
Obstruction Alert is issued when, in the controller’s
judgment, an aircraft’s altitude places it in unsafe
proximity to terrain and/or obstructions; and
2. Aircraft Conflict/Mode C Intruder Alert.
An Aircraft Conflict/Mode C Intruder Alert is issued
if the controller observes another aircraft which
places it in an unsafe proximity. When feasible, thecontroller will offer the pilot an alternative course of
action.
FIG 3−2−1
Airspace Classes
MSL - mean sea level
AGL - above ground levelFL - flight levelCLASS BCLASS B
CLASS CCLASS CCLASS ECLASS E
CLASS DCLASS D
CLASS GCLASS G CLASS GCLASS G CLASS GCLASS GNontowered
AirportNontowered
AirportFL 600
18,000 MSLFL 600
18,000 MSL
14,500 MSL14,500 MSL
1,200 AGL 700 AGLCLASS ACLASS A
AIM 10/12/17
3−2−2 Controlled Airspaceg. Ultralight V ehicles. No person may operate an
ultralight vehicle within Class A, Class B, Class C, or
Class D airspace or within the lateral boundaries of
the surface area of Class E airspace designated for an
airport unless that person has prior authorization from
the ATC facility having jurisdiction over that
airspace. (See 14 CFR Part 103.)
h. Unmanned Free Balloons. Unless otherwise
authorized by ATC, no person may operate an
unmanned free balloon below 2,000 feet above the
surface within the lateral boundaries of Class B,Class C, Class D, or Class E airspace designated for
an airport. (See 14 CFR Part 101.)
i. Parachute Jumps. No person may make a
parachute jump, and no pilot −in−command may
allow a parachute jump to be made from that aircraft,
in or into Class A, Class B, Class C, or Class Dairspace without, or in violation of, the terms of an
ATC authorization issued by the ATC facility having
jurisdiction over the airspace. (See 14 CFR Part 105.)
3−2−2. Class A Airspace
a. Definition. Generally, that airspace from
18,000 feet MSL up to and including FL 600,including the airspace overlying the waters within
12 nautical miles off the coast of the 48 contiguous
States and Alaska; and designated internationalairspace beyond 12 nautical miles off the coast of the
48 contiguous States and Alaska within areas of
domestic radio navigational signal or ATC radarcoverage, and within which domestic procedures are
applied.
b. Operating Rules and Pilot/Equipment
Requirements. Unless otherwise authorized, all
persons must operate their aircraft under IFR. (See14 CFR Section 71.33 and 14 CFR Section 91.167
through 14 CFR Section 91.193.)
c. Charts. Class A airspace is not specifically
charted.
3−2−3. Class B Airspace
a. Definition. Generally, that airspace from the
surface to 10,000 feet MSL surrounding the nation’sbusiest airports in terms of IFR operations or
passenger enplanements. The configuration of each
Class B airspace area is individually tailored andconsists of a surface area and two or more layers
(some Class B airspace areas resemble upside-down
wedding cakes), and is designed to contain all
published instrument procedures once an aircraft
enters the airspace. An ATC clearance is required for
all aircraft to operate in the area, and all aircraft that
are so cleared receive separation services within the
airspace. The cloud clearance requirement for VFRoperations is “clear of clouds.”
b. Operating Rules and Pilot/Equipment
Requirements for VFR Operations. Regardless of
weather conditions, an ATC clearance is requiredprior to operating within Class B airspace. Pilots
should not request a clearance to operate within
Class B airspace unless the requirements of 14 CFRSection 91.215 and 14 CFR Section 91.131 are met.
Included among these requirements are:
1.Unless otherwise authorized by ATC, aircraft
must be equipped with an operable two-way radio
capable of communicating with ATC on appropriate
frequencies for that Class B airspace.
2.No person may take off or land a civil aircraft
at the following primary airports within Class B
airspace unless the pilot −in−command holds at least
a private pilot certificate:
(a)Andrews Air Force Base, MD
(b)Atlanta Hartsfield Airport, GA
(c)Boston Logan Airport, MA
(d)Chicago O’Hare Intl. Airport, IL
(e)Dallas/Fort Worth Intl. Airport, TX
(f)Los Angeles Intl. Airport, CA
(g)Miami Intl. Airport, FL
(h)Newark Intl. Airport, NJ
(i)New York Kennedy Airport, NY
(j)New York La Guardia Airport, NY
(k)Ronald Reagan Washington National
Airport, DC
(l)San Francisco Intl. Airport, CA
3.No person may take off or land a civil aircraft
at an airport within Class B airspace or operate a civil
aircraft within Class B airspace unless:
(a)The pilot −in−command holds at least a
private pilot certificate; or
AIM 10/12/17
3−2−3 Controlled Airspace(b)The aircraft is operated by a student pilot
or recreational pilot who seeks private pilot
certification and has met the requirements of 14 CFR
Section 61.95.
4.Unless otherwise authorized by ATC, each
person operating a large turbine engine-powered
airplane to or from a primary airport must operate ator above the designated floors while within the lateral
limits of Class B airspace.
5.Unless otherwise authorized by ATC, each
aircraft must be equipped as follows:
(a)For IFR operations, an operable VOR or
TACAN receiver or an operable and suitable RNA V
system; and
(b)For all operations, a two-way radio
capable of communications with ATC on appropriate
frequencies for that area; and
(c)Unless otherwise authorized by ATC, an
operable radar beacon transponder with automatic
altitude reporting equipment.
NOTE−
ATC may, upon notification, immediately authorize adeviation from the altitude reporting equipment require-
ment; however, a request for a deviation from the 4096
transponder equipment requirement must be submitted tothe controlling ATC facility at least one hour before theproposed operation.
REFERENCE −
AIM, Paragraph 4 −1−20 , Transponder Operation
6. Mode C Veil. The airspace within 30 nauti-
cal miles of an airport listed in Appendix D, Section 1
of 14 CFR Part 91 (generally primary airports within
Class B airspace areas), from the surface upward to10,000 feet MSL. Unless otherwise authorized by
ATC, aircraft operating within this airspace must be
equipped with automatic pressure altitude reportingequipment having Mode C capability.
However, an aircraft that was not originally
certificated with an engine −driven electrical system
or which has not subsequently been certified with asystem installed may conduct operations within a
Mode C veil provided the aircraft remains outside
Class A, B or C air space; and below the altitude of the
ceiling of a Class B or Class C airspace area
designated for an airport or 10,000 feet MSL,
whichever is lower.c. Charts. Class B airspace is charted on
Sectional Charts, IFR En Route Low Altitude, and
Terminal Area Charts.
d. Flight Procedures.
1. Flights. Aircraft within Class B airspace are
required to operate in accordance with current IFR
procedures. A clearance for a visual approach to aprimary airport is not authorization for turbine −
powered airplanes to operate below the designated
floors of the Class B airspace.
2. VFR Flights.
(a)Arriving aircraft must obtain an ATC
clearance prior to entering Class B airspace and must
contact ATC on the appropriate frequency, and inrelation to geographical fixes shown on local charts.
Although a pilot may be operating beneath the floor
of the Class B airspace on initial contact,communications with ATC should be established in
relation to the points indicated for spacing and
sequencing purposes.
(b)Departing aircraft require a clearance to
depart Class B airspace and should advise the
clearance delivery position of their intended altitudeand route of flight. ATC will normally advise VFR
aircraft when leaving the geographical limits of the
Class B airspace. Radar service is not automaticallyterminated with this advisory unless specifically
stated by the controller.
(c)Aircraft not landing or departing the
primary airport may obtain an ATC clearance totransit the Class B airspace when traffic conditions
permit and provided the requirements of 14 CFR
Section 91.131 are met. Such VFR aircraft are
encouraged, to the extent possible, to operate at
altitudes above or below the Class B airspace ortransit through established VFR corridors. Pilots
operating in VFR corridors are urged to use frequency
122.750 MHz for the exchange of aircraft positioninformation.
e. ATC Clearances and Separation. An ATC
clearance is required to enter and operate within
Class B airspace. VFR pilots are provided sequenc-ing and separation from other aircraft while operating
within Class B airspace.
REFERENCE −
AIM, Paragraph 4 −1−18 , Terminal Radar Services for VFR Aircraft
AIM 10/12/17
3−2−4 Controlled AirspaceNOTE−
1.Separation and sequencing of VFR aircraft will be
suspended in the event of a radar outage as this service is
dependent on radar. The pilot will be advised that the
service is not available and issued wind, runway
information and the time or place to contact the tower.
2.Separation of VFR aircraft will be suspended during
CENRAP operations. Traffic advisories and sequencing to
the primary airport will be provided on a workload
permitting basis. The pilot will be advised when centerradar presentation (CENRAP) is in use.
1.VFR aircraft are separated from all VFR/IFR
aircraft which weigh 19,000 pounds or less by a
minimum of:
(a)Target resolution, or
(b)500 feet vertical separation, or
(c)Visual separation.
2.VFR aircraft are separated from all VFR/IFR
aircraft which weigh more than 19,000 and turbojets
by no less than:
(a)1 1/2 miles lateral separation, or
(b)500 feet vertical separation, or
(c)Visual separation.
3.This program is not to be interpreted as
relieving pilots of their responsibilities to see andavoid other traffic operating in basic VFR weather
conditions, to adjust their operations and flight path
as necessary to preclude serious wake encounters, tomaintain appropriate terrain and obstruction clear-
ance or to remain in weather conditions equal to or
better than the minimums required by 14 CFR
Section 91.155. Approach control should be advised
and a revised clearance or instruction obtained whencompliance with an assigned route, heading and/or
altitude is likely to compromise pilot responsibility
with respect to terrain and obstruction clearance,vortex exposure, and weather minimums.
4.ATC may assign altitudes to VFR aircraft that
do not conform to 14 CFR Section 91.159.
“RESUME APPROPRIATE VFR ALTITUDES”
will be broadcast when the altitude assignment is nolonger needed for separation or when leaving Class B
airspace. Pilots must return to an altitude that
conforms to 14 CFR Section 91.159.
f. Proximity operations. VFR aircraft operating
in proximity to Class B airspace are cautioned againstoperating too closely to the boundaries, especially
where the floor of the Class B airspace is 3,000 feet
or less above the surface or where VFR cruise
altitudes are at or near the floor of higher levels.
Observance of this precaution will reduce thepotential for encountering an aircraft operating at the
altitudes of Class B floors. Additionally, VFR aircraft
are encouraged to utilize the VFR Planning Chart asa tool for planning flight in proximity to Class B
airspace. Charted VFR Flyway Planning Charts are
published on the back of the existing VFR TerminalArea Charts.
3−2−4. Class C Airspace
a. Definition. Generally, that airspace from the
surface to 4,000 feet above the airport elevation
(charted in MSL) surrounding those airports that have
an operational control tower, are serviced by a radarapproach control, and that have a certain number of
IFR operations or passenger enplanements. Although
the configuration of each Class C airspace area isindividually tailored, the airspace usually consists of
a 5 NM radius core surface area that extends from the
surface up to 4,000 feet above the airport elevation,and a 10 NM radius shelf area that extends no lower
than 1,200 feet up to 4,000 feet above the airport
elevation.
b. Charts. Class C airspace is charted on
Sectional Charts, IFR En Route Low Altitude, and
Terminal Area Charts where appropriate.
c. Operating Rules and Pilot/Equipment
Requirements:
1. Pilot Certification. No specific certifica-
tion required.
2. Equipment.
(a)Two-way radio; and
(b)Unless otherwise authorized by ATC, an
operable radar beacon transponder with automaticaltitude reporting equipment.
NOTE−
See paragraph 4 −1−20, Transponder Operation, subpara-
graph f2(c) for Mode C transponder requirements for
operating above Class C airspace.
3. Arrival or Through Flight Entry Require-
ments. Two-way radio communication must be
established with the ATC facility providing ATC
services prior to entry and thereafter maintain those
communications while in Class C airspace. Pilots of
AIM 10/12/17
3−2−5 Controlled Airspacearriving aircraft should contact the Class C airspace
ATC facility on the publicized frequency and give
their position, altitude, radar beacon code, destina-
tion, and request Class C service. Radio contact
should be initiated far enough from the Class Cairspace boundary to preclude entering Class C
airspace before two-way radio communications are
established.
NOTE−
1.If the controller responds to a radio call with, “(air craft
callsign) standby,” radio communications have been
established and the pilot can enter the Class C airspace.
2.If workload or traffic conditions prevent immediate
provision of Class C services, the contr oller will inform the
pilot to remain outside the Class C airspace until
conditions permit the services to be provided.
3.It is important to understand that if the controller
responds to the initial radio call without using the aircraft
identification, radio communications have not beenestablished and the pilot may not enter the Class C
airspace.
4.Though not requiring regulatory action, Class C
airspace areas have a procedural Outer Area. Normally
this area is 20 NM from the primary Class C airspace
airport. Its vertical limit extends from the lower limits ofradio/radar coverage up to the ceiling of the approach
control’ s delegated airspace, excluding the Class C
airspace itself, and other airspace as appropriate. (Thisouter area is not charted.)
5.Pilots approaching an air port with Class C service
should be aware that if they descend below the base altitude
of the 5 to 10 mile shelf during an instrument or visual
approach, they may encounter nontransponder, VFRaircraft.
EXAMPLE −
1.[Aircraft callsign] “remain outside the Class Charlie
airspace and standby.”
2.“Aircraft calling Dulles approach control, standby.”
4. Departures from:
(a)A primary or satellite airport with an
operating control tower. Two-way radio communica-
tions must be established and maintained with thecontrol tower, and thereafter as instructed by ATC
while operating in Class C airspace.
(b)A satellite airport without an operating
control tower. Two-way radio communications mustbe established as soon as practicable after departing
with the ATC facility having jurisdiction over the
Class C airspace.5. Aircraft Speed. Unless otherwise autho-
rized or required by ATC, no person may operate an
aircraft at or below 2,500 feet above the surface
within 4 nautical miles of the primary airport of a
Class C airspace area at an indicated airspeed of more
than 200 knots (230 mph).
d. Air Traffic Services. When two-way radio
communications and radar contact are established, all
VFR aircraft are:
1.Sequenced to the primary airport.
2.Provided Class C services within the Class C
airspace and the outer area.
3.Provided basic radar services beyond the
outer area on a workload permitting basis. This can be
terminated by the controller if workload dictates.
e. Aircraft Separation. Separation is provided
within the Class C airspace and the outer area after
two-way radio communications and radar contact are
established. VFR aircraft are separated from IFRaircraft within the Class C airspace by any of the
following:
1.Visual separation.
2.500 feet vertical separation.
3.Target resolution.
4.Wake turbulence separation will be provided
to all aircraft operating:
(a)Behind and less than 1,000 feet below
super or heavy aircraft,
(b)To small aircraft operating behind and less
than 500 feet below B757 aircraft, and
(c)To small aircraft following a large aircraft
on final approach.
NOTE−
1.Separation and sequencing of VFR aircraft will be
suspended in the event of a radar outage as this service is
dependent on radar. The pilot will be advised that the
service is not available and issued wind, runwayinformation and the time or place to contact the tower.
2.Separation of VFR aircraft will be suspended during
CENRAP operations. Traffic advisories and sequencing to
the primary airport will be provided on a workload
permitting basis. The pilot will be advised when CENRAP
is in use.
3.Pilot participation is voluntary within the outer area
and can be discontinued, within the outer area, at the pilot’ s
request. Class C services will be provided in the outer area
unless the pilot requests termination of the service.
AIM 10/12/17
3−2−6 Controlled Airspace4.Some facilities provide Class C services only during
published hours. At other times, terminal IFR radar service
will be provided. It is important to note that the
communications and transponder requirements are
dependent of the class of airspace established outside of the
published hours.
f. Secondary Airports
1.In some locations Class C airspace may
overlie the Class D surface area of a secondaryairport. In order to allow that control tower to provide
service to aircraft, portions of the overlapping
Class C airspace may be procedurally excluded when
the secondary airport tower is in operation. Aircraft
operating in these procedurally excluded areas will
only be provided airport traffic control services when
in communication with the secondary airport tower.
2.Aircraft proceeding inbound to a satellite
airport will be terminated at a sufficient distance to
allow time to change to the appropriate tower oradvisory frequency . Class C services to these aircraft
will be discontinued when the aircraft is instructed to
contact the tower or change to advisory frequency.
3.Aircraft departing secondary controlled
airports will not receive Class C services until they
have been radar identified and two-way communica-
tions have been established with the Class C airspace
facility.
4.This program is not to be interpreted as
relieving pilots of their responsibilities to see and
avoid other traffic operating in basic VFR weatherconditions, to adjust their operations and flight path
as necessary to preclude serious wake encounters, to
maintain appropriate terrain and obstruction clear-ance or to remain in weather conditions equal to or
better than the minimums required by 14 CFR
Section 91.155. Approach control should be advised
and a revised clearance or instruction obtained when
compliance with an assigned route, heading and/oraltitude is likely to compromise pilot responsibility
with respect to terrain and obstruction clearance,
vortex exposure, and weather minimums.
g. Class C Airspace Areas by State
These states currently have designated Class C
airspace areas that are depicted on sectional charts.Pilots should consult current sectional charts and
NOTAMs for the latest information on services
available. Pilots should be aware that some Class Cairspace underlies or is adjacent to Class B airspace.
(See TBL 3 −2−1.)
TBL 3−2−1
Class C Airspace Areas by State
State/City Airport
ALABAMA
Birmingham ......... Birmingham −Shuttlesworth
International
Huntsville ........... International −Carl T Jones Fld
Mobile .............. Regional
ALASKA
Anchorage ........... Ted Stevens International
ARIZONA
Davis−Monthan ....... AFB
Tucson .............. International
ARKANSAS
Fayetteville (Springdale) Northwest Arkansas Regional
Little Rock .......... Adams Field
CALIFORNIA
Beale ............... AFB
Burbank ............ Bob Hope
Fresno .............. Yosemite International
Monterey ............ Peninsula
Oakland ............. Metropolitan Oakland
International
Ontario ............. International
Riverside ............ March AFB
Sacramento .......... International
San Jose ............ Norman Y . Mineta International
Santa Ana ........... John Wayne/Orange County
Santa Barbara ........ Municipal
COLORADO
Colorado Springs ..... Municipal
CONNECTICUT
Windsor Locks ....... Bradley International
FLORIDA
Daytona Beach ....... International
Fort Lauderdale ....... Hollywood International
Fort Myers .......... SW Florida Regional
Jacksonville .......... International
Orlando ............. Sanford International
Palm Beach .......... International
Pensacola ........... NAS
Pensacola ........... Regional
Sarasota ............. Bradenton International
Tallahassee .......... Regional
Whiting ............. NAS
GEORGIA
Savannah ............ Hilton Head International
HAWAII
Kahului ............. Kahului
IDAHO
Boise ............... Air Terminal
ILLINOIS
Champaign .......... Urbana U of Illinois −Willard
AIM 10/12/17
3−2−7 Controlled AirspaceState/City Airport
Chicago ............. Midway International
Moline .............. Quad City International
Peoria .............. Greater Peoria Regional
Springfield .......... Abraham Lincoln Capital
INDIANA
Evansville ........... Regional
Fort Wayne .......... International
Indianapolis .......... International
South Bend .......... Regional
IOWA
Cedar Rapids ......... The Eastern Iowa
Des Moines .......... International
KANSAS
Wichita ............. Mid−Continent
KENTUCKY
Lexington ........... Blue Grass
Louisville ........... International −Standiford Field
LOUISIANA
Baton Rouge ......... Metropolitan, Ryan Field
Lafayette ............ Regional
Shreveport ........... Barksdale AFB
Shreveport ........... Regional
MAINE
Bangor ............. International
Portland ............. International Jetport
MICHIGAN
Flint ................ Bishop International
Grand Rapids ........ Gerald R. Ford International
Lansing ............. Capital City
MISSISSIPPI
Columbus ........... AFB
Jackson ............. Jackson−Evers International
MISSOURI
Springfield .......... Springfield −Branson National
MONTANA
Billings ............. Logan International
NEBRASKA
Lincoln ............. Lincoln
Omaha .............. Eppley Airfield
Offutt ............... AFB
NEV ADA
Reno ............... Reno/Tahoe International
NEW HAMPSHIRE
Manchester .......... Manchester
NEW JERSEY
Atlantic City ......... International
NEW MEXICO
Albuquerque ......... International Sunport
NEW YORK
Albany ............. International
Buffalo ............. Niagara International
Islip ................ Long Island MacArthur
Rochester ........... Greater Rochester International
Syracuse ............ Hancock InternationalState/City Airport
NORTH CAROLINA
Asheville ........... Regional
Fayetteville .......... Regional/Grannis Field
Greensboro .......... Piedmont Triad International
Pope ............... AFB
Raleigh ............. Raleigh−Durham International
OHIO
Akron .............. Akron−Canton Regional
Columbus ........... Port Columbus International
Dayton ............. James M. Cox International
Toledo .............. Express
OKLAHOMA
Oklahoma City ....... Will Rogers World
Tinker .............. AFB
Tulsa ............... International
OREGON
Portland ............. International
PENNSYLV ANIA
Allentown ........... Lehigh Valley International
PUERTO RICO
San Juan ............ Luis Munoz Marin International
RHODE ISLAND
Providence .......... Theodore Francis Green State
SOUTH CAROLINA
Charleston ........... AFB/International
Columbia ............ Metropolitan
Greer ............... Greenville −Spartanburg
International
Myrtle Beach ........ Myrtle Beach International
Shaw ............... AFB
TENNESSEE
Chattanooga ......... Lovell Field
Knoxville ........... McGhee Tyson
Nashville ............ International
TEXAS
Abilene ............. Regional
Amarillo ............ Rick Husband International
Austin .............. Austin−Bergstrom International
Corpus Christi ........ International
Dyess .............. AFB
El Paso ............. International
Harlingen ........... Valley International
Laughlin ............ AFB
Lubbock ............ Preston Smith International
Midland ............. International
San Antonio ......... International
VERMONT
Burlington ........... International
VIRGIN ISLANDS
St. Thomas .......... Charlotte Amalie Cyril E. King
VIRGINIA
Richmond ........... International
Norfolk ............. International
AIM 10/12/17
3−2−8 Controlled AirspaceState/City Airport
Roanoke ............ Regional/Woodrum Field
WASHINGTON
Point Roberts ........ Vancouver International
Spokane ............ Fairchild AFB
Spokane ............ International
Whidbey Island ....... NAS, Ault Field
WEST VIRGINIA
Charleston ........... Yeager
WISCONSIN
Green Bay ........... Austin Straubel International
Madison ............ Dane County Regional −Traux
Field
Milwaukee .......... General Mitchell International
3−2−5. Class D Airspace
a. Definition. Generally, Class D airspace ex-
tends upward from the surface to 2,500 feet above the
airport elevation (charted in MSL) surrounding those
airports that have an operational control tower. Theconfiguration of each Class D airspace area is
individually tailored and when instrument proce-
dures are published, the airspace will normally be
designed to contain the procedures.
1.Class D surface areas may be designated as
full-time (24 hour tower operations) or part-time.Part-time Class D ef fective times are published in the
Chart Supplement U.S.
2.Where a Class D surface area is part-time, the
airspace may revert to either a Class E surface area(see paragraph 3 −2−6e1) or Class G airspace. When
a part–time Class D surface area changes to Class G,
the surface area becomes Class G airspace up to, but
not including, the overlying controlled airspace.
NOTE−
1.The airport listing in the Chart Supplement U.S. will
state the part–time surface area status (for example, “other
times CLASS E” or “other times CLASS G”).
2.Normally, the overlying controlled airspace is the Class
E transition area airspace that begins at either 700 feetAGL (charted as magenta vignette) or 1200 feet AGL
(charted as blue vignette). This may be determined by
consulting the applicable VFR Sectional or Terminal Area
Charts.
b. Operating Rules and Pilot/Equipment
Requirements:
1. Pilot Certification. No specific certifica-
tion required.2. Equipment. Unless otherwise authorized
by ATC, an operable two −way radio is required.
3. Arrival or Through Flight Entry
Requirements. Two−way radio communication
must be established with the ATC facility providing
ATC services prior to entry and thereafter maintain
those communications while in t he Class D airspace.
Pilots of arriving aircraft should contact the control
tower on the publicized frequency and give their
position, altitude, destination, and any request(s).Radio contact should be initiated far enough from the
Class D airspace boundary to preclude entering the
Class D airspace before two −way radio communica-
tions are established.
NOTE−
1.If the controller responds to a radio call with, “[air craft
callsign] standby,” radio communications have beenestablished and the pilot can enter the Class D airspace.
2.If workload or traffic conditions prevent immediate
entry into Class D airspace, the controller will inform thepilot to remain outside the Class D airspace until
conditions permit entry.
EXAMPLE −
1.“[Aircraft callsign] remain outside the Class Delta
airspace and standby.”
It is important to understand that if the contr oller responds
to the initial radio call without using the aircraft callsign,radio communications have not been established and the
pilot may not enter the Class D airspace.
2.“Aircraft calling Manassas tower standby.”
At those airports where the control tower does not operate
24 hours a day, the operating hours of the tower will be
listed on the appropriate charts and in the Chart
Supplement U.S. During the hours the tower is not inoperation, the Class E surface ar ea rules or a combination
of Class E rules to 700 feet above ground level and Class
G rules to the surface will become applicable. Check theChart Supplement U.S. for specifics.
4. Departures from:
(a)A primary or satellite airport with an
operating control tower. Two-way radio communica-
tions must be established and maintained with thecontrol tower, and thereafter as instructed by ATC
while operating in the Class D airspace.
(b)A satellite airport without an operating
control tower. Two-way radio communications must
be established as soon as practicable after departingwith the ATC facility having jurisdiction over the
Class D airspace as soon as practicable after
departing.
AIM 10/12/17
3−2−9 Controlled Airspace5. Aircraft Speed. Unless otherwise autho-
rized or required by ATC, no person may operate an
aircraft at or below 2,500 feet above the surface
within 4 nautical miles of the primary airport of a
Class D airspace area at an indicated airspeed of more
than 200 knots (230 mph).
c.Class D airspace areas are depicted on Sectional
and Terminal charts with blue segmented lines, andon IFR En Route Lows with a boxed [D].
d.Surface area arrival extensions:
1.Class D surface area arrival extensions for
instrument approach procedures may be Class D or
Class E airspace. As a general rule, if all extensionsare 2 miles or less, they remain part of the Class D
surface area. However, if any one extension is greater
than 2 miles, then all extensions will be Class Eairspace.
2. Surface area arrival extensions are effective
during the published times of the surface area. For
part–time Class D surface areas that revert to Class E
airspace, the arrival extensions will remain in effectas Class E airspace. For part–time Class D surface
areas that change to Clas s G airspace, the arrival
extensions will become Class G at the same time.
e. Separation for VFR Aircraft. No separation
services are provided to VFR aircraft.
3−2−6. Class E Airspace
a. Definition. Class E airspace is controlled
airspace that is designated to serve a variety of
terminal or en route purposes as described in this
paragraph.
b. Operating Rules and Pilot/Equipment
Requirements:
1. Pilot Certification. No specific certifica-
tion required.
2. Equipment. No specific equipment
required by the airspace.
3. Arrival or Through Flight Entry Require-
ments. No specific requirements.
c. Charts. Class E airspace below 14,500 feet
MSL is charted on Sectional, Terminal, and IFREnroute Low Altitude charts.
d. Vertical limits. Except where designated at a
lower altitude (see paragraph 3 −2−6e, below, forspecifics), Class E airspace in the United States
consists of:
1.The airspace extending upward from 14,500
feet MSL to, but not including, 18,000 feet MSL
overlying the 48 contiguous states, the District ofColumbia and Alaska, including the waters within
nautical 12 miles from the coast of the 48 contiguous
states and Alaska; excluding:
(a)The Alaska peninsula west of longit-
ude 160
/C009500'00''W.; and
(b) The airspace below 1,500 feet above the
surface of the earth unless specifically designated
lower (for example, in mountainous terrain higher
than 13,000 feet MSL).
2.The airspace above FL 600 is Class E
airspace.
e. Functions of Class E Airspace. Class E
airspace may be designated for the following
purposes:
1. Surface area designated for an airport
where a control tower is not in operation. Class E
surface areas extend upward from the surface to adesignated altitude, or to the adjacent or overlying
controlled airspace. The airspace will be configured
to contain all instrument procedures.
(a)To qualify for a Class E surface area, the
airport must have weather observation and reporting
capability, and communications capability must exist
with aircraft down to the runway surface.
(b)A Class E surface area may also be
designated to accommodate part-time operations at a
Class C or Class D airspace location (for example,
those periods when the control tower is not inoperation).
(c)Pilots should refer to the airport page in
the applicable Chart Supplement U.S. for surface areastatus information.
2. Extension to a surface area. Class E
airspace may be designated as extensions to Class B,
Class C, Class D, and Class E surface areas. Class E
airspace extensions begin at the surface and extend up
to the overlying controlled airspace. The extensionsprovide controlled airspace to contain standard
instrument approach procedures without imposing a
communications requirement on pilots operatingunder VFR. Surface area arrival extensions become
part of the surface area and are in effect during the
same times as the surface area.
AIM 10/12/17
3−2−10 Controlled AirspaceNOTE−
When a Class C or Class D surface area is not in effectcontinuously (for example, where a control tower onlyoperates part-time), the surface area airspace will change
to either a Class E surface area or Class G airspace. In
such cases, the “Airspace” entry for the airport in theChart Supplement U.S. will state “other times Class E” or
“other times Class G.” When a part-time surface areachanges to Class E airspace, the Class E arrival extensions
will remain in effect as Class E airspace. If a part–time
Class C, Class D, or Class E surface area becomes ClassG airspace, the arrival extensions will change to Class Gat the same time.
3. Airspace used for transition. Class E
airspace areas may be designated for transitioning
aircraft to/from the terminal or en route environment.
(a)Class E transition areas extend upward
from either 700 feet AGL (shown as magenta vignette
on sectional charts) or 1,200 feet AGL (blue vignette)
and are designated for airports with an approved
instrument procedure.
(b)The 700-foot/1200-foot AGL Class E
airspace transition areas remain in effect continu-
ously, regardless of airport operating hours or surface
area status.
NOTE−
Do not confuse the 700-foot and 1200-foot Class E
transition areas with surface areas or surface areaextensions.
4. En Route Domestic Areas. There are
Class E airspace areas th at extend upward from a
specified altitude and are en route domestic airspaceareas that provide controlled airspace in those areas
where there is a requirement to provide IFR en routeATC services but the Federal airway system is
inadequate.
5. Federal Airways and Low-Altitude RNA V
Routes. Federal airways and low-altitude RNA V
routes are Class E airspace areas and, unless
otherwise specified, extend upward from 1,200 feet
AGL to, but not including,18,000 feet MSL.
(a)Federal airways consist of Low/Medium
Frequency (L/MF) airways (colored Federal airways)
and VOR Federal airways.
(1)L/MF airways are based on non −direc-
tional beacons (NDB) and are identified as green, red,
amber, or blue.
(2)VOR Federal airways are based on
VOR/VORTAC facilities and are identified by a “V”
prefix.
(b)Low-altitude RNA V routes consist of
T-routes and helicopter RNA V routes (TK-routes).
NOTE−
See AIM Paragraph 5-3-4, Airways and Route Systems, formore details and charting information.
6. Offshore Airspace Areas. There are
Class E airspace areas that extend upward from aspecified altitude to, but not including, 18,000 feet
MSL and are designated as offshore airspace areas.
These areas provide controlled airspace beyond12 miles from the coast of the U.S. in those areas
where there is a requirement to provide IFR en route
ATC services and within which the U.S. is applyingdomestic procedures.
f. Separation for VFR Aircraft. No separation
services are provided to VFR aircraft.
AIM 10/12/17
3−3−1 Class G AirspaceSection 3. Class G Airspace
3−3−1. General
Class G airspace (uncontrolled) is that portion of
airspace that has not been designated as Class A,Class B, Class C, Class D, or Class E airspace.
3−3−2. VFR Requirements
Rules governing VFR flight have been adopted to
assist the pilot in meeting the responsibility to see and
avoid other aircraft. Minimum flight visibility anddistance from clouds required for VFR flight are
contained in 14 CFR Section 91.155.
(See TBL 3 −1−1.)3−3−3. IFR Requirements
a.Title 14 CFR specifies the pilot and aircraft
equipment requirements for IFR flight. Pilots are
reminded that in addition to altitude or flight levelrequirements, 14 CFR Section 91.177 includes a
requirement to remain at least 1,000 feet (2,000 feet
in designated mountainous terrain) above the highest
obstacle within a horizontal distance of 4 nautical
miles from the course to be flown.
b.IFR Altitudes.
(See TBL 3 −3−1.)
TBL 3−3−1
IFR Altitudes
Class G Airspace
If your magnetic course
(ground track) is:And you are below
18,000 feet MSL, fly:
0/C0095 to 179 /C0095 Odd thousands MSL, (3,000; 5,000; 7,000, etc.)
180/C0095 to 359 /C0095 Even thousands MSL, (2,000; 4,000; 6,000, etc.)
AIM 10/12/17
3−4−1 Special Use AirspaceSection 4. Special Use Airspace
3−4−1. General
a.Special use airspace consists of that airspace
wherein activities must be confined because of their
nature, or wherein limitations are imposed uponaircraft operations that are not a part of those
activities, or both. Except for controlled firing areas,
special use airspace areas are depicted on aeronauti-cal charts.
b.Prohibited and restricted areas are regulatory
special use airspace and are established in 14 CFR
Part 73 through the rulemaking process.
c.Warning areas, military operations areas
(MOAs), alert areas, and controlled firing areas
(CFAs) are nonregulatory special use airspace.
d.Special use airspace descriptions (except CFAs)
are contained in FAA Order JO 7400.8, Special Use
Airspace.
e.Special use airspace (except CFAs) are charted
on IFR or visual charts and include the hours of
operation, altitudes, and the controlling agency.
3−4−2. Prohibited Areas
Prohibited areas contain airspace of defined
dimensions identified by an area on the surface of the
earth within which the flight of aircraft is prohibited.
Such areas are established for security or other
reasons associated with the national welfare. Theseareas are published in the Federal Register and are
depicted on aeronautical charts.
3−4−3. Restricted Areas
a.Restricted areas contain airspace identified by
an area on the surface of the earth within which theflight of aircraft, while not wholly prohibited, is
subject to restrictions. Activities within these areas
must be confined because of their nature orlimitations imposed upon aircraft operations that are
not a part of those activities or both. Restricted areas
denote the existence of unusual, often invisible,hazards to aircraft such as artillery firing, aerial
gunnery, or guided missiles. Penetration of restricted
areas without authorization from the using orcontrolling agency may be extremely hazardous to
the aircraft and its occupants. Restricted areas are
published in the Federal Register and constitute
14 CFR Part 73.
b.ATC facilities apply the following procedures
when aircraft are operating on an IFR clearance
(including those cleared by ATC to maintain
VFR-on-top) via a route which lies within joint-use
restricted airspace.
1.If the restricted area is not active and has been
released to the controlling agency (FAA), the ATC
facility will allow the aircraft to operate in the
restricted airspace without issuing specific clearance
for it to do so.
2.If the restricted area is active and has not been
released to the controlling agency (FAA), the ATC
facility will issue a clearance which will ensure theaircraft avoids the restricted airspace unless it is on an
approved altitude reservation mission or has obtained
its own permission to operate in the airspace and soinforms the controlling facility.
NOTE−
The above apply only to joint-use restricted airspace and
not to prohibited and nonjoint-use airspace. For the lattercategories, the ATC facility will issue a clearance so theaircraft will avoid the r estricted airspace unless it is on an
approved altitude reservation mission or has obtained its
own permission to operate in the airspace and so informs
the controlling facility.
c.Restricted airspace is depicted on the en route
chart appropriate for use at the altitude or flight level
being flown. For joint-use restricted areas, the name
of the controlling agency is shown on these charts.For all prohibited areas and nonjoint-use restricted
areas, unless otherwise requested by the using
agency, the phrase “NO A/G” is shown.
3−4−4. Warning Areas
A warning area is airspace of defined dimensions,
extending from three nautical miles outward from the
coast of the U.S., that contains activity that may be
hazardous to nonparticipating aircraft. The purposeof such warning areas is to warn nonparticipating
pilots of the potential danger. A warning area may be
located over domestic or international waters or both.
AIM 10/12/17
3−4−2 Special Use Airspace3−4−5. Military Operations Areas
a.MOAs consist of airspace of defined vertical
and lateral limits established for the purpose of
separating certain military training activities fromIFR traffic. Whenever a MOA is being used,
nonparticipating IFR traffic may be cleared through
a MOA if IFR separation can be provided by ATC.Otherwise, A TC will reroute or restrict nonparticipat-
ing IFR traffic.
b.Examples of activities conducted in MOAs
include, but are not limited to: air combat tactics, airintercepts, aerobatics, formation training, and
low−altitude tactics. Military pilots flying in an active
MOA are exempted from the provisions of 14 CFRSection 91.303(c) and (d) which prohibits aerobatic
flight within Class D and Class E surface areas, and
within Federal airways. Additionally, the Department
of Defense has been issued an authorization to
operate aircraft at indicated airspeeds in excess of250 knots below 10,000 feet MSL within active
MOAs.
c.Pilots operating under VFR should exercise
extreme caution while flying within a MOA whenmilitary activity is being conducted. The activity
status (active/inactive) of MOAs may change
frequently. Therefore, pilots should contact any FSSwithin 100 miles of the area to obtain accurate
real-time information concerning the MOA hours of
operation. Prior to entering an active MOA, pilots
should contact the controlling agency for traffic
advisories.
d.MOAs are depicted on sectional, VFR T erminal
Area, and Enroute Low Altitude charts.3−4−6. Alert Areas
Alert areas are depicted on aeronautical charts to
inform nonparticipating pilots of areas that maycontain a high volume of pilot training or an unusual
type of aerial activity. Pilots should be particularly
alert when flying in these areas. All activity within an
alert area must be conducted in accordance with
CFRs, without waiver, and pilots of participating
aircraft as well as pilots transiting the area must beequally responsible for collision avoidance.
3−4−7. Controlled Firing Areas
CFAs contain activities which, if not conducted in a
controlled environment, could be hazardous tononparticipating aircraft. The distinguishing feature
of the CFA, as compared to other special use airspace,
is that its activities are suspended immediately whenspotter aircraft, radar, or ground lookout positions
indicate an aircraft might be approaching the area.
There is no need to chart CFAs since they do not cause
a nonparticipating aircraft to change its flight path.
3−4−8. National Security Areas
National Security Areas consist of airspace of defined
vertical and lateral dimensions established at
locations where there is a requirement for increased
security and safety of ground facilities. Pilots arerequested to voluntarily avoid flying through the
depicted NSA. When it is necessary to provide a
greater level of security and safety, flight in NSAsmay be temporarily prohibited by regulation under
the provisions of 14 CFR Section 99.7. Regulatory
prohibitions will be issued by System Operations,System Operations Airspace and AIM Office,
Airspace and Rules, and disseminated via NOTAM.
Inquiries about NSAs should be directed to Airspace
and Rules.
AIM 10/12/17
3−5−1 Other Airspace AreasSection 5. Other Airspace Areas
3−5−1. Airport Advisory/Information
Services
a.There are two advisory type services available
at selected airports.
1.Local Airport Advisory (LAA) service is
available only in Alaska and is operated within 10
statute miles of an airport where a control tower is not
operating but where a FSS is located on the airport. At
such locations, the FSS provides a complete local
airport advisory service to arriving and departingaircraft. During periods of fast changing weather the
FSS will automatically provide Final Guard as part of
the service from the time the aircraft reports“on−final” or “taking−the−active−runway” until the
aircraft reports “on −the−ground” or “airborne.”
NOTE−
Current policy, when requesting remote ATC services,requires that a pilot monitor the automated weatherbroadcast at the landing airport prior to requesting ATCservices. The FSS automatically provides Final Guard,
when appropriate, during LAA/Remote Airport Advisory
(RAA) operations. Final Guard is a value addedwind/altimeter monitoring service, which provides anautomatic wind and altimeter check during active weather
situations when the pilot reports on −final or taking the
active runway. During the landing or take −off operation
when the winds or altimeter are actively changing the FSS
will blind broadcast significant changes when thespecialist believes the change might affect the operation.Pilots should acknowledge the first wind/altimeter check
but due to cockpit activity no acknowledgement is expected
for the blind broadcasts. It is prudent for a pilot to reporton−the−ground or airborne to end the service.
2.Remote Airport Information Service (RAIS)
is provided in support of short term special events like
small to medium fly −ins. The service is advertised by
NOTAM D only. The FSS will not have access to a
continuous readout of the current winds and
altimeter; therefore, RAIS does not include weatherand/or Final Guard service. However, known traffic,
special event instructions, and all other services are
provided.
NOTE−
The airport authority and/or manager should r equest RAIS
support on official letterhead directly with the manager of
the FSS that will provide the service at least 60 days inadvance. Approval authority rests with the FSS managerand is based on workload and resource availability.REFERENCE −
AIM, Paragraph 4 −1−9 , Traffic Advisory Practices at Airports Without
Operating Control Towers
b.It is not mandatory that pilots participate in the
Airport Advisory programs. Participation enhancessafety for everyone operating around busy GA
airports; therefore, everyone is encouraged to
participate and provide feedback that will helpimprove the program.
3−5−2. Military Training Routes
a.National security depends largely on the
deterrent effect of our airborne military forces. To be
proficient, the military services must train in a wide
range of airborne tactics. One phase of this training
involves “low level” combat tactics. The requiredmaneuvers and high speeds are such that they may
occasionally make the see-and-avoid aspect of VFR
flight more difficult without increased vigilance in
areas containing such operations. In an effort to
ensure the greatest practical level of safety for allflight operations, the Military Training Route (MTR)
program was conceived.
b.The MTR program is a joint venture by the FAA
and the Department of Defense (DOD). MTRs are
mutually developed for use by the military for the
purpose of conducting low-altitude, high-speedtraining. The routes above 1,500 feet AGL are
developed to be flown, to the maximum extent
possible, under IFR. The routes at 1,500 feet AGLand below are generally developed to be flown under
VFR.
c.Generally, MTRs are established below
10,000 feet MSL for operations at speeds in excess of
250 knots. However, route segments may be defined
at higher altitudes for purposes of route continuity.For example, route segments may be defined for
descent, climbout, and mountainous terrain. There
are IFR and VFR routes as follows:
1. IFR Military Training Routes −(IR).
Operations on these routes are conducted in
accordance with IFR regardless of weatherconditions.
2. VFR Military Training Routes −(VR).
Operations on these routes are conducted inaccordance with VFR except flight visibility must be
AIM 10/12/17
3−5−2 Other Airspace Areas5 miles or more; and flights must not be conducted
below a ceiling of less than 3,000 feet AGL.
d.Military training routes will be identified and
charted as follows:
1. Route identification.
(a)MTRs with no segment above 1,500 feet
AGL must be identified by four number characters;
e.g., IR1206, VR1207.
(b)MTRs that include one or more segments
above 1,500 feet AGL must be identified by three
number characters; e.g., IR206, VR207.
(c)Alternate IR/VR routes or route segments
are identified by using the basic/principal routedesignation followed by a letter suffix, e.g., IR008A,
VR1007B, etc.
2. Route charting.
(a) IFR Enroute Low Altitude Chart. This
chart will depict all IR routes and all VR routes that
accommodate operations above 1,500 feet AGL.
(b) VFR Sectional Aeronautical
Charts. These charts will depict military training
activities such as IR, VR, MOA, Restricted Area,Warning Area, and Alert Area information.
(c) Area Planning (AP/1B) Chart (DOD
Flight Information Publication −FLIP). This chart
is published by the National Geospatial −Intelligence
Agency (NGA) primarily for military users and
contains detailed information on both IR and VR
routes.
REFERENCE −
AIM, Paragraph 9 −1−5 , Subparagraph a, National
Geospatial −Intelligence Agency (NGA) Products
e.The FLIP contains charts and narrative
descriptions of these routes. To obtain this
publication contact:
Defense Logistics Agency for Aviation
Mapping Customer Operations (DLA A VN/QAM)
8000 Jefferson Davis Highway
Richmond, V A 23297 −5339
Toll free phone: 1 −800−826−0342
Commercial: 804 −279−6500
This NGA FLIP is available for pilot briefings at FSS
and many airports.
f.Nonparticipating aircraft are not prohibited
from flying within an MTR; however, extremevigilance should be exercised when conducting flight
through or near these routes. Pilots should contact
FSSs within 100 NM of a particular MTR to obtain
current information or route usage in their vicinity.
Information available includes times of scheduledactivity, altitudes in use on each route segment, and
actual route width. Route width varies for each MTR
and can extend several miles on either side of thecharted MTR centerline. Route width information for
IR and VR MTRs is also available in the FLIP AP/1B
along with additional MTR (slow routes/air refuelingroutes) information. When requesting MTR informa-
tion, pilots should give the FSS their position, route
of flight, and destination in order to reduce frequency
congestion and permit the FSS specialist to identify
the MTR which could be a factor.
3−5−3. Temporary Flight Restrictions
a. General. This paragraph describes the types of
conditions under which the FAA may imposetemporary flight restrictions. It also explains which
FAA elements have been delegated authority to issue
a temporary flight restrictions NOTAM and lists thetypes of responsible agencies/offices from which the
FAA will accept requests to establish temporary
flight restrictions. The 14 CFR is explicit as to whatoperations are prohibited, restricted, or allowed in a
temporary flight restrictions area. Pilots are responsi-
ble to comply with 14 CFR Sections 91.137, 91.138,91.141 and 91.143 when conducting flight in an area
where a temporary flight restrictions area is in effect,
and should check appropriate NOTAMs during flightplanning.
b. The purpose for establishing a temporary
flight restrictions area is to:
1.Protect persons and property in the air or on
the surface from an existing or imminent hazard
associated with an incident on the surface when thepresence of low flying aircraft would magnify, alter,
spread, or compound that hazard (14 CFR
Section 91.137(a)(1));
2.Provide a safe environment for the operation
of disaster relief aircraft (14 CFR Sec-
tion 91.137(a)(2)); or
3.Prevent an unsafe congestion of sightseeing
aircraft above an incident or event which may
generate a high degree of public interest (14 CFR
Section 91.137(a)(3)).
AIM 10/12/17
3−5−3 Other Airspace Areas4.Protect declared national disasters for
humanitarian reasons in the State of Hawaii (14 CFR
Section 91.138).
5.Protect the President, Vice President, or other
public figures (14 CFR Section 91.141).
6.Provide a safe environment for space agency
operations (14 CFR Section 91.143).
c.Except for hijacking situations, when the
provisions of 14 CFR Section 91.137(a)(1) or (a)(2)
are necessary, a temporary flight restrictions area willonly be established by or through the area manager at
the Air Route Traffic Control Center (ARTCC)
having jurisdiction over the area concerned. Atemporary flight restrictions NOTAM involving the
conditions of 14 CFR Section 91.137(a)(3) will be
issued at the direction of the service area officedirector having oversight of the airspace concerned.
When hijacking situations are involved, a temporary
flight restrictions area will be implemented throughthe TSA A viation Command Center. The appropriate
FAA air traffic element, upon receipt of such a
request, will establish a temporary flight restrictions
area under 14 CFR Section 91.137(a)(1).
d.The FAA accepts recommendations for the
establishment of a temporary flight restrictions area
under 14 CFR Section 91.137(a)(1) from militarymajor command headquarters, regional directors of
the Office of Emergency Planning, Civil Defense
State Directors, State Governors, or other similarauthority. For the situations involving 14 CFR
Section 91.137(a)(2), the FAA accepts recommenda-
tions from military commanders serving as regional,subregional, or Search and Rescue (SAR) coordina-
tors; by military commanders directing or
coordinating air operations associated with disaster
relief; or by civil authorities directing or coordinating
organized relief air operations (includes representa-tives of the Office of Emergency Planning, U.S.
Forest Service, and State aeronautical agencies).
Appropriate authorities for a temporary flightrestrictions establishment under 14 CFR
Section 91.137(a)(3) are any of those listed above or
by State, county, or city government entities.
e.The type of restrictions issued will be kept to a
minimum by the FAA consistent with achievement of
the necessary objective. Situations which warrant the
extreme restrictions of 14 CFR Section 91.137(a)(1)
include, but are not limited to: toxic gas leaks orspills, flammable agents, or fumes which if fanned by
rotor or propeller wash could endanger persons or
property on the surface, or if entered by an aircraft
could endanger persons or property in the air;
imminent volcano eruptions which could endangerairborne aircraft and occupants; nuclear accident or
incident; and hijackings. Situations which warrant
the restrictions associated with 14 CFR Sec-tion 91.137(a)(2) include: forest fires which are
being fought by releasing fire retardants from
aircraft; and aircraft relief activities following adisaster (earthquake, tidal wave, flood, etc.). 14 CFR
Section 91.137(a)(3) restrictions are established for
events and incidents that would attract an unsafecongestion of sightseeing aircraft.
f.The amount of airspace needed to protect
persons and property or provide a safe environment
for rescue/relief aircraft operations is normally
limited to within 2,000 feet above the surface andwithin a 3 −nautical−mile radius. Incidents occurring
within Class B, Class C, or Class D airspace will
normally be handled through existing procedures and
should not require the issuance of a temporary flight
restrictions NOTAM. Temporary flight restrictions
affecting airspace outside of the U.S. and itsterritories and possessions are issued with verbiage
excluding that airspace outside of the 12 −mile coastal
limits.
g.The FSS nearest the incident site is normally the
“coordination facility.” When FAA communicationsassistance is required, the designated FSS will
function as the primary communications facility for
coordination between emergency control authoritiesand affected aircraft. The ARTCC may act as liaison
for the emergency control authorities if adequate
communications cannot be established between the
designated FSS and the relief organization. For
example, the coordination facility may relay
authorizations from the on-scene emergency re-sponse official in cases where news media aircraft
operations are approved at the altitudes used by relief
aircraft.
h.ATC may authorize operations in a temporary
flight restrictions area under its own authority onlywhen flight restrictions are established under 14 CFR
Section 91.137(a)(2) and (a)(3). The appropriate
ARTCC/airport traffic control tower manager will,however, ensure that such authorized flights do not
hamper activities or interfere with the event for which
restrictions were implemented. However, ATC will
AIM 10/12/17
3−5−4 Other Airspace Areasnot authorize local IFR flights into the temporary
flight restrictions area.
i.To preclude misunderstanding, the implement-
ing NOTAM will contain specific and formattedinformation. The facility establishing a temporary
flight restrictions area will format a NOTAM
beginning with the phrase “FLIGHT RESTRIC-
TIONS” followed by: the location of the temporary
flight restrictions area; the effective period; the areadefined in statute miles; the altitudes affected; the
FAA coordination facility and commercial telephone
number; the reason for the temporary flightrestrictions; the agency directing any relief activities
and its commercial telephone number; and other
information considered appropriate by the issuingauthority.
EXAMPLE −
1.14 CFR Section 91.137(a)(1):
The following NOTAM prohibits all aircraft operations
except those specified in the NOTAM.
Flight restrictions Matthews, Virginia, effective immedi-ately until 9610211200. Pursuant to 14 CFR
Section 91.137(a)(1) temporary flight restrictions are in
effect. Rescue operations in progress. Only relief aircraftoperations under the direction of the Department ofDefense are authorized in the airspace at and below
5,000 feet MSL within a 2 −nautical−mile radius of Laser
AFB, Matthews, Virginia. Commander, Laser AFB, incharge (897) 946 −5543 (122.4). Steenson FSS
(792) 555 −6141 (123.1) is the F AA coordination facility.
2.14 CFR Section 91.137(a)(2):
The following NOTAM permits flight operations inaccordance with 14 CFR Section 91.137(a)(2). The on-site
emergency response official to authorize media aircraft
operations below the altitudes used by the relief aircraft.Flight restrictions 25 miles east of Bransome, Idaho,
effective immediately until 9601202359 UTC. Pursuant to
14 CFR Section 91.137(a)(2) temporary flight restrictions
are in effect within a 4 −nautical−mile radius of the
intersection of county roads 564 and 315 at and below
3,500 feet MSL to provide a safe environment for firefighting aircraft operations. Davis County sheriff’ s
department (792) 555 −8122 (122.9) is in charge of
on-scene emergency response activities. Glivings FSS(792) 555 −1618 (122.2) is the F AA coordination facility.
3.14 CFR Section 91.137(a)(3):
The following NOTAM prohibits sightseeing aircraft
operations.Flight restrictions Brown, Tennessee, due to olympic
activity. Effective 9606181100 UTC until 9607190200UTC . Pursuant to 14 CFR Section 91.137(a)(3) temporary
flight restrictions are in effect within a 3 −nautical−mile
radius of N355783/W835242 and Volunteer VORTAC 019
degree radial 3.7 DME fix at and below 2,500 feet MSL.
Norton FSS (423) 555 −6742 (126.6) is the F AA
coordination facility.
4.14 CFR Section 91.138:
The following NOTAM prohibits all aircraft except those
operating under the authorization of the official in charge
of associated emergency or disaster relief responseactivities, aircraft carrying law enforcement officials,
aircraft carrying personnel involved in an emergency or
legitimate scientific purposes, carrying properly accred-ited news media, and air craft operating in accordance with
an ATC clearance or instruction.
Flight r estrictions Kapalua, Hawaii, effective 9605101200
UTC until 9605151500 UTC. Pursuant to 14 CFR
Section 91.138 temporary flight restrictions are in effect
within a 3 −nautical−mile radius of N205778/W1564038
and Maui/OGG/VORTAC 275 degree radial at 14.1nautical miles. John Doe 808 −757−4469 or 122.4 is in
charge of the operation. Honolulu/HNL 808 −757−
(123.6) FSS is the F AA coordination facility.
5.14 CFR Section 91.141:
The following NOTAM prohibits all aircraft.Flight restrictions Stillwater, Oklahoma, June 21, 1996.
Pursuant to 14 CFR Section 91.141 aircraft flight
operations are pr ohibited within a 3 −nautical−mile radius,
below 2000 feet AGL of N360962/W970515 and the
Stillwater/SWO/VOR/DME 176 degree radial 3.8 −nauti-
cal−mile fix from 1400 local time to 1700 local time
June 21, 1996, unless otherwise authorized by ATC.
6.14 CFR Section 91.143:
The following NOTAM prohibits any aircraft of U.S.registry, or pilot any aircraft under the authority of an
airman certificate issued by the F AA.
Kennedy space center space operations area effectiveimmediately until 9610152100 UTC. Pursuant to 14 CFR
Section 91.143, flight operations conducted by F AA
certificated pilots or conducted in air craft of U.S. registry
are prohibited at any altitude from surface to unlimited,
within the following area 30 −nautical−mile radius of the
Melbourne/MLB/VORTAC 010 degree radial 21 −nauti-
cal−mile fix. St. Petersburg, Florida/PIE/FSS
813−545−1645 (122.2) is the F AA coordination facility and
should be contacted for the current status of any airspaceassociated with the space shuttle operations. This airspace
encompasses R2933, R2932, R2931, R2934, R2935,
W497A and W158A. Additional warning and restrictedareas will be active in conjunction with the operations.
Pilots must consult all NOTAMs regarding this operation.
AIM 10/12/17
3−5−5 Other Airspace Areas3−5−4. Parachute Jump Aircraft Operations
a.Procedures relating to parachute jump areas are
contained in 14 CFR Part 105. Tabulations of
parachute jump areas in the U.S. are contained in the
Chart Supplement U.S.
b.Pilots of aircraft engaged in parachute jump
operations are reminded that all reported altitudes
must be with reference to mean sea level, or flight
level, as appropriate, to enable ATC to providemeaningful traffic information.
c.Parachute operations in the vicinity of an airport
without an operating control tower − there is no
substitute for alertness while in the vicinity of an
airport. It is essential that pilots conducting parachute
operations be alert, look for other traffic, and
exchange traffic information as recommended inParagraph 4 −1−9, Traffic Advisory Practices at
Airports Without Operating Control Towers. In
addition, pilots should avoid releasing parachuteswhile in an airport traffic pattern when there are other
aircraft in that pattern. Pilots should make
appropriate broadcasts on the designated CommonTraffic Advisory Frequency (CTAF), and monitor
that CTAF until all parachute activity has terminated
or the aircraft has left the area. Prior to commencinga jump operation, the pilot should broadcast theaircraft’s altitude and position in relation to the
airport, the approximate relative time when the jump
will commence and terminate, and listen to the
position reports of other aircraft in the area.
3−5−5. Published VFR Routes
Published VFR routes for transitioning around, under
and through complex airspace such as Class Bairspace were developed through a number of FAA
and industry initiatives. All of the following terms,
i.e., “VFR Flyway” “VFR Corridor” and “Class BAirspace VFR Transition Route” have been used
when referring to the same or different types of routes
or airspace. The following paragraphs identify andclarify the functionality of each type of route, and
specify where and when an ATC clearance is
required.
a. VFR Flyways.
1.VFR Flyways and their associated Flyway
Planning Charts were developed from the recommen-
dations of a National Airspace Review Task Group.
A VFR Flyway is defined as a general flight path notdefined as a specific course, for use by pilots in
planning flights into, out of, through or near complex
terminal airspace to avoid Class B airspace. An ATC
clearance is NOT required to fly these routes.
AIM 10/12/17
3−5−6 Other Airspace AreasFIG 3−5−1
VFR Flyway Planning Chart
AIM 10/12/17
3−5−7 Other Airspace Areas2.VFR Flyways are depicted on the reverse side
of some of the VFR Terminal Area Charts (TAC),
commonly referred to as Class B airspace charts. (See
FIG 3−5−1.) Eventually all TACs will include a VFR
Flyway Planning Chart. These charts identify VFRflyways designed to help VFR pilots avoid major
controlled traffic flows. They may further depict
multiple VFR routings throughout the area whichmay be used as an alternative to flight within Class B
airspace. The ground references provide a guide for
improved visual navigation. These routes are notintended to discourage requests for VFR operations
within Class B airspace but are designed solely to
assist pilots in planning for flights under and aroundbusy Class B airspace without actually entering
Class B airspace.
3.It is very important to remember that these
suggested routes are not sterile of other traffic. Theentire Class B airspace, and the airspace underneath
it, may be heavily congested with many different
types of aircraft. Pilot adherence to VFR rules mustbe exercised at all times. Further, when operating
beneath Class B airspace, communications must be
established and maintained between your aircraft and
any control tower while transiting the Class B,
Class C, and Class D surface areas of those airports
under Class B airspace.
b. VFR Corridors.
1.The design of a few of the first Class B
airspace areas provided a corridor for the passage ofuncontrolled traffic. A VFR corridor is defined as
airspace through Class B airspace, with defined
vertical and lateral boundaries, in which aircraft may
operate without an ATC clearance or communication
with air traffic control.
2.These corridors are, in effect, a “hole”
through Class B airspace. (See FIG 3 −5−2.) A classic
example would be the corridor through the Los
Angeles Class B airspace, which has been subse-
quently changed to Special Flight Rules airspace(SFR). A corridor is surrounded on all sides by
Class B airspace and does not extend down to the
surface like a VFR Flyway. Because of their finitelateral and vertical limits, and the volume of VFRtraffic using a corridor, extreme caution and vigilance
must be exercised.
FIG 3−5−2
Class B Airspace
3.Because of the heavy traffic volume and the
procedures necessary to efficiently manage the flow
of traffic, it has not been possible to incorporate VFR
corridors in the development or modifications ofClass B airspace in recent years.
c. Class B Airspace VFR Transition Routes.
1.To accommodate VFR traffic through certain
Class B airspace, such as Seattle, Phoenix and
Los Angeles, Class B Airspace VFR TransitionRoutes were developed. A Class B Airspace VFR
Transition Route is defined as a specific flight course
depicted on a TAC for transiting a specific Class Bairspace. These routes include specific AT C-assigned
altitudes, and pilots must obtain an ATC clearance
prior to entering Class B airspace on the route.
2.These routes, as depicted in FIG 3−5−3, are
designed to show the pilot where to position the
aircraft outside of, or clear of, the Class B airspace
where an ATC clearance can normally be expectedwith minimal or no delay. Until ATC authorization is
received, pilots must remain clear of Class B
airspace. On initial contact, pilots should advise ATC
of their position, altitude, route name desired, and
direction of flight. After a clearance is received, pilots
must fly the route as depicted and, most importantly,adhere to ATC instructions.
AIM 10/12/17
3−5−8 Other Airspace AreasFIG 3−5−3
VFR Transition Route
AIM 10/12/17
3−5−9 Other Airspace Areas3−5−6. Terminal Radar Service Area (TRSA)
a. Background. TRSAs were originally estab-
lished as part of the Terminal Radar Program at
selected airports. TRSAs were never controlledairspace from a regulatory standpoint because the
establishment of TRSAs was never subject to the
rulemaking process; consequently, TRSAs are not
contained in 14 CFR Part 71 nor are there any TRSA
operating rules in 14 CFR Part 91. Part of the Airport
Radar Service Area (ARSA) program was to
eventually replace all TRSAs. However, the ARSA
requirements became relatively stringent and it wassubsequently decided that TRSAs would have to
meet ARSA criteria before they would be converted.
TRSAs do not fit into any of the U.S. airspace classes;
therefore, they will continue to be non −Part 71
airspace areas where participating pilots can receive
additional radar services which have been redefinedas TRSA Service.
b. TRSAs. The primary airport(s) within the
TRSA become(s) Class D airspace. The remaining
portion of the TRSA overlies other controlled
airspace which is normally Class E airspacebeginning at 700 or 1,200 feet and established to
transition to/from the en route/terminal environment.
c. Participation. Pilots operating under VFR are
encouraged to contact the radar approach control and
avail themselves of the TRSA Services. However,
participation is voluntary on the part of the pilot. See
Chapter 4, Air Traffic Control, for details and
procedures.
d. Charts. TRSAs are depicted on VFR sectional
and terminal area charts with a solid black line and
altitudes for each segment. The Class D portion is
charted with a blue segmented line.
3−5−7. Special Air Traffic Rules (SATR) and
Special Flight Rules Area (SFRA)
a. Background. The Code of Federal Regulations
(CFR) prescribes special air traffic rules for aircraft
operating within the boundaries of certain designated
airspace. These areas are listed in 14 CFR Part 93 and
can be found throughout the NAS. Procedures, nature
of operations, configuration, size, and density of
traffic vary among the identified areas.
b. SFRAs. Airspace of defined dimensions, above
land areas or territorial waters, within which the flight
of aircraft is subject to the rules set forth in 14 CFRPart 93, unless otherwise authorized by air traffic
control. Not all areas listed in 14 CFR Part 93 are
designated SFRA, but special air traffic rules apply to
all areas described in 14 CFR Part 93.
REFERENCE −
14 CFR Part 93, Special Air Traffic Rules
F AA Order JO 7110.65, Para 9 −2−10, Special Air T raffic Rules (SATR)
and Special Flight Rules Area (SFRA)
PCG − Special Air T raffic Rules (SATR)
c. Participation. Each person operating an
aircraft to, from, or within airspace designated as a
SATR area or SFRA must adhere to the special air
traffic rules set forth in 14 CFR Part 93, as applicable,
unless otherwise authorized or required by ATC.
d. Charts. SFRAs are depicted on VFR sectional,
terminal area, and helicopter route charts. (See
FIG 3−5−4.)
FIG 3−5−4
SFRA Boundary
e.Additional information and resources regarding
SFRA, including procedures for flight in individual
areas, may be found on the FAA Safety website at
www.faasafety.gov.
3−5−8. Weather Reconnaissance Area
(WRA)
a. General. Hurricane Hunters from the United
States Air Force Reserve 53rd Weather
Reconnaissance Squadron (WRS) and the National
Oceanic and Atmospheric Administration (NOAA)
Aircraft Operations Center (AOC) operate weather
reconnaissance/research aircraft missions, in support
of the National Hurricane Operations Plan (NHOP),
to gather meteorological data on hurricanes and
tropical cyclones. 53rd WRS and NOAA AOC
aircraft normally conduct these missions in airspace
AIM 10/12/17
3−5−10 Other Airspace Areasidentified in a published WRA Notice to Airmen
(NOTAM).
b. WRAs. Airspace with defined dimensions and
published by a NOTAM, which is established to
support weather reconnaissance/research flights.
ATC services are not provided within WRAs. Only
participating weather reconnaissance/research
aircraft from the 53rd WRS and NOAA AOC are
permitted to operate within a WRA. A WRA may
only be established in airspace within U. S. FlightInformation Regions (FIR) outside of U. S. territorial
airspace.
c.A published WRA NOTAM describes the
airspace dimensions of the WRA and the expected
activities within the WRA. WRAs may border
adjacent foreign FIRs, but are wholly contained
within U.S. FIRs. As ATC services are not provided
within a WRA, non −participating aircraft should
avoid WRAs, and IFR aircraft should expect to be
rerouted to avoid WRAs.
AIM 10/12/17
4−1−1 Services Available to PilotsChapter 4. Air Traffic Control
Section 1. Services Available to Pilots
4−1−1. Air Route Traffic Control Centers
Centers are established primarily to provide air traffic
service to aircraft operating on IFR flight plans within
controlled airspace, and principally during the
en route phase of flight.
4−1−2. Control Towers
Towers have been established to provide for a safe,
orderly and expeditious flow of traffic on and in the
vicinity of an airport. When the responsibility hasbeen so delegated, towers also provide for the
separation of IFR aircraft in the terminal areas.
REFERENCE −
AIM, Paragraph 5 −4−3 , Approach Control
4−1−3. Flight Service Stations
Flight Service Stations (FSSs) are air traffic
facilities which provide pilot briefings, flight plan
processing, en route flight advisories, search andrescue services, and assistance to lost aircraft and
aircraft in emer gency situations. FSSs also relay ATC
clearances, process Notices to Airmen, broadcast
aviation weather and aeronautical information, and
advise Customs and Border Protection of transborder
flights. In Alaska, designated FSSs also provide
TWEB recordings, take weather observations, and
provide Airport Advisory Services (AAS).
4−1−4. Recording and Monitoring
a.Calls to air traffic control (ATC) facilities
(ARTCCs, Towers, FSSs, Central Flow, and
Operations Centers) over radio and ATC operationaltelephone lines (lines used for operational purposes
such as controller instructions, briefings, opening and
closing flight plans, issuance of IFR clearances andamendments, counter hijacking activities, etc.) may
be monitored and recorded for operational uses such
as accident investigations, accident prevention,search and rescue purposes, specialist training andevaluation, and technical evaluation and repair of
control and communications systems.
b.Where the public access telephone is recorded,
a beeper tone is not required. In place of the “beep”tone the FCC has substituted a mandatory require-
ment that persons to be recorded be given notice they
are to be recorded and give consent. Notice is given
by this entry, consent to record is assumed by the
individual placing a call to the operational facility.
4−1−5. Communications Release of IFR
Aircraft Landing at an Airport Without an
Operating Control Tower
Aircraft operating on an IFR flight plan, landing at an
airport without an operating control tower will be
advised to change to the airport advisory frequency
when direct communications with ATC are no longer
required. Towers and centers do not have nontowerairport traffic and runway in use information. The
instrument approach may not be aligned with the
runway in use; therefore, if the information has notalready been obtained, pilots should make an
expeditious change to the airport advisory frequency
when authorized.
REFERENCE −
AIM, Paragraph 5 −4−4 , Advance Information on Instrument Approach
4−1−6. Pilot Visits to Air Traffic Facilities
Pilots are encouraged to participate in local pilot/air
traffic control outreach activities. However, due to
security and workload concerns, requests for airtraffic facility visits may not always be approved.
Therefore, visit requests should be submitted through
the air traffic facility as early as possible. Pilotsshould contact the facility and advise them of the
number of persons in the group, the time and date of
the proposed visit, and the primary interest of thegroup. The air traffic facility will provide further
instructions if a request can be approved.
REFERENCE −
F AA Order 1600.69, F AA Facility Security Management Program
AIM 10/12/17
4−1−2 Services Available to Pilots4−1−7. Operation Rain Check
Operation Rain Check is a program designed and
managed by local air traffic control facility
management. Its purpose is to familiarize pilots and
aspiring pilots with the ATC system, its functions,
responsibilities and benefits.
REFERENCE −
FAA Order JO 7210.3, Paragraph 4 −2−2, Pilot Education
F AA Order 1600.69, F AA Facility Security Management Program
4−1−8. Approach Control Service for VFR
Arriving Aircraft
a.Numerous approach control facilities have
established programs for arriving VFR aircraft tocontact approach control for landing information.
This information includes: wind, runway, and
altimeter setting at the airport of intended landing.This information may be omitted if contained in the
Automatic Terminal Information Service (ATIS)
broadcast and the pilot states the appropriate ATIScode.
NOTE−
Pilot use of “have numbers” does not indicate receipt of the
ATIS broadcast. In addition, the controller will providetraffic advisories on a workload permitting basis.
b.Such information will be furnished upon initial
contact with concerned approach control facility. The
pilot will be requested to change to the tower
frequency at a predetermined time or point, to receive
further landing information.
c.Where available, use of this procedure will not
hinder the operation of VFR flights by requiringexcessive spacing between aircraft or devious
routing.
d.Compliance with this procedure is not
mandatory but pilot participation is encouraged.
REFERENCE −
AIM, Paragraph 4 −1−18 , Terminal Radar Services for VFR Aircraft
NOTE−
Approach control services for VFR aircraft are normally
dependent on ATC radar . These services are not available
during periods of a radar outage. Approach controlservices for VFR aircraft are limited when CENRAP is inuse.
4−1−9. Traffic Advisory Practices at
Airports Without Operating Control Towers
(See TBL 4 −1−1.)a. Airport Operations Without Operating
Control Tower
1.There is no substitute for alertness while in
the vicinity of an airport. It is essential that pilots be
alert and look for other traffic and exchange trafficinformation when approaching or departing an
airport without an operating control tower. This is of
particular importance since other aircraft may nothave communication capability or, in some cases,
pilots may not communicate their presence or
intentions when operating into or out of such airports.
To achieve the greatest degree of safety, it is essential
that all radio-equipped aircraft transmit/receive on a
common frequency identified for the purpose ofairport advisories.
2.An airport may have a full or part-time tower
or FSS located on the airport, a full or part-timeUNICOM station or no aeronautical station at all.
There are three ways for pilots to communicate their
intention and obtain airport/traffic information when
operating at an airport that does not have an operating
tower: by communicating with an FSS, a UNICOMoperator, or by making a self-announce broadcast.
NOTE−
FSS airport advisories are available only in Alaska.
3.Many airports are now providing completely
automated weather, radio check capability and airport
advisory information on an automated UNICOM
system. These systems offer a variety of features,typically selectable by microphone clicks, on the
UNICOM frequency. Availability of the automated
UNICOM will be published in the Chart Supplement
U.S. and approach charts.
b. Communicating on a Common Frequency
1.The key to communicating at an airport
without an operating control tower is selection of the
correct common frequency. The acronym CTAFwhich stands for Common Traffic Advisory
Frequency, is synonymous with this program. A
CTAF is a frequency designated for the purpose ofcarrying out airport advisory practices while
operating to or from an airport without an operating
control tower. The CTAF may be a UNICOM,MULTICOM, FSS, or tower frequency and is
identified in appropriate aeronautical publications.
NOTE−
FSS frequencies are available only in Alaska.
AIM 10/12/17
4−1−3 Services Available to PilotsTBL 4−1−1
Summary of Recommended Communication Procedures
Communication/Broadcast Procedures
Facility at Airport Frequency Use Outbound InboundPractice
Instrument
Approach
1.UNICOM (No Tower or
FSS)Communicate with UNICOMstation on published CTAF
frequency (122.7; 122.8; 122.725;122.975; or 123.0). If unable tocontact UNICOM station, useself-announce procedures onCTAF.Before taxiing and
before taxiing on
the runway fordeparture.10 miles out.
Entering
downwind, base,and final. Leavingthe runway.
2.No Tower, FSS, or
UNICOMSelf-announce on MULTICOMfrequency 122.9. Before taxiing andbefore taxiing on
the runway fordeparture.10 miles out.
Entering
downwind, base,and final. Leavingthe runway.Departing final
approach fix
(name) or on finalapproach segmentinbound.
3.No Tower in operation,
FSS open (Alaska only)Communicate with FSS on CTAFfrequency. Before taxiing andbefore taxiing on
the runway fordeparture.10 miles out.
Entering
downwind, base,and final. Leavingthe runway.Approach com-
pleted/terminated.
4.FSS Closed (No Tower) Self-announce on CTAF. Before taxiing andbefore taxiing on
the runway fordeparture.10 miles out.
Entering
downwind, base,and final. Leavingthe runway.
5.Tower or FSS not in
operationSelf-announce on CTAF. Before taxiing andbefore taxiing on
the runway fordeparture.10 miles out.
Entering
downwind, base,and final. Leavingthe runway.
6.Designated CTAF Area
(Alaska Only)Self-announce on CTAFdesignated on chart or Chart
Supplement Alaska.Before taxiing and
before taxiing on
the runway fordeparture untilleaving designatedarea.When entering
designated CTAF
area.
2. CTAF (Alaska Only) . In Alaska, a CTAF
may also be designated for the purpose of carrying out
advisory practices while operating in designated
areas with a high volume of VFR traffic.
3.The CTAF frequency for a particular airport
or area is contained in the Chart Supplement U.S.,
Chart Supplement Alaska, Alaska Terminal Publica-
tion, Instrument Approach Procedure Charts, andInstrument Departure Procedure (DP) Charts. Also,
the CTAF frequency can be obtained by contacting
any FSS. Use of the appropriate CTAF, combinedwith a visual alertness and application of the
following recommended good operating practices,
will enhance safety of flight into and out of all
uncontrolled airports.c. Recommended Traffic Advisory Practices
1.Pilots of inbound traffic should monitor and
communicate as appropriate on the designated CTAF
from 10 miles to landing. Pilots of departing aircraft
should monitor/communicate on the appropriatefrequency from start-up, during taxi, and until
10 miles from the airport unless the CFRs or local
procedures require otherwise.
2.Pilots of aircraft conducting other than
arriving or departing operations at altitudes normally
used by arriving and departing aircraft should
monitor/communicate on the appropriate frequency
while within 10 miles of the airport unless required to
do otherwise by the CFRs or local procedures. Such
AIM 10/12/17
4−1−4 Services Available to Pilotsoperations include parachute jumping/dropping, en
route, practicing maneuvers, etc.
3.In Alaska, pilots of aircraft conducting other
than arriving or departing operations in designatedCTAF areas should monitor/communicate on the
appropriate frequency while within the designated
area, unless required to do otherwise by CFRs or local
procedures. Such operations include parachute
jumping/dropping, en route, practicing maneuvers,
etc.
REFERENCE −
AIM, Paragraph 3 −5−4 , Parachute Jump Aircraft Operations
d. Airport Advisory/Information Services
Provided by a FSS
1.There are two advisory type services
provided at selected airports.
(a)Local Airport Advisory (LAA) is avail-
able only in Alaska and provided at airports that have
a FSS physically located on the airport, which doesnot have a control tower or where the tower is
operated on a part −time basis. The CTAF for LAA
airports is disseminated in the appropriate aeronauti-
cal publications.
(b)Remote Airport Information Ser-
vice (RAIS) is provided in support of special events
at nontowered airports by request from the airportauthority.
2.In communicating with a CTAF FSS, check
the airport’s automated weather and establish
two−way communications before transmitting out-
bound/inbound intentions or information. Aninbound aircraft should initiate contact approximate-
ly 10 miles from the airport, reporting aircraft
identification and type, altitude, location relative to
the airport, intentions (landing or over flight),
possession of the automated weather, and requestairport advisory or airport information service. A
departing aircraft should initiate contact before
taxiing, reporting aircraft identification and type,VFR or IFR, location on the airport, intentions,
direction of take −off, possession of the automated
weather, and request airport advisory or informationservice. Also, report intentions before taxiing onto
the active runway for departure. If you must change
frequencies for other service after initial report toFSS, return to FSS frequency for traffic update.
(a)InboundEXAMPLE −
Vero Beach radio, Centurion Six Niner Delta Delta isten miles south, two thousand, landing Vero Beach. I have
the automated weather, request airport advisory.
(b)Outbound
EXAMPLE −
Vero Beach radio, Centurion Six Niner Delta Delta, ready
to taxi to runway 22, VFR, departing to the southwest. I
have the automated weather, request airport advisory.
3.Airport advisory service includes wind
direction and velocity, favored or designated runway,
altimeter setting, known airborne and ground traffic,
NOTAMs, airport taxi routes, airport traffic patterninformation, and instrument approach procedures.
These elements are varied so as to best serve the
current traffic situation. Some airport managers have
specified that under certain wind or other conditions
designated runways be used. Pilots should advise the
FSS of the runway they intend to use.
CAUTION −
All aircraft in the vicinity of an airport may not be in
communication with the FSS.
e. Information Provided by Aeronautical
Advisory Stations (UNICOM)
1.UNICOM is a nongovernment air/ground
radio communication station which may provide
airport information at public use airports where there
is no tower or FSS.
2.On pilot request, UNICOM stations may
provide pilots with weather information, wind
direction, the recommended runway, or othernecessary information. If the UNICOM frequency is
designated as the CTAF, it will be identified in
appropriate aeronautical publications.
f. Unavailability of Information from FSS or
UNICOM
Should LAA by an FSS or Aeronautical Advisory
Station UNICOM be unavailable, wind and weatherinformation may be obtainable from nearby
controlled airports via Automatic Terminal Informa-
tion Service (ATIS) or Automated WeatherObserving System (AWOS) frequency.
g. Self-Announce Position and/or Intentions
1. General. Self-announce is a procedure
whereby pilots broadcast their position or intendedflight activity or ground operation on the designated
CTAF. This procedure is used primarily at airports
which do not have an FSS on the airport. The
AIM 10/12/17
4−1−5 Services Available to Pilotsself-announce procedure should also be used if a pilot
is unable to communicate with the FSS on the
designated CTAF . Pilots stating, “Traffic in the area,
please advise” is not a recognized Self −Announce
Position and/or Intention phrase and should not beused under any condition.
2.If an airport has a tower and it is temporarily
closed, or operated on a part-time basis and there is no
FSS on the airport or the FSS is closed, use the CTAF
to self-announce your position or intentions.
3.Where there is no tower, FSS, or UNICOM
station on the airport, use MULTICOM frequency
122.9 for self-announce procedures. Such airports
will be identified in appropriate aeronauticalinformation publications.
4. Practice Approaches. Pilots conducting
practice instrument approaches should be particular-
ly alert for other aircraft that may be departing in theopposite direction. When conducting any practice
approach, regardless of its direction relative to other
airport operations, pilots should make announce-ments on the CTAF as follows:
(a)Departing the final approach fix, inbound
(nonprecision approach) or departing the outer
marker or fix used in lieu of the outer marker, inbound
(precision approach);
(b)Established on the final approach segment
or immediately upon being released by ATC;
(c)Upon completion or termination of the
approach; and
(d)Upon executing the missed approach
procedure.
5.Departing aircraft should always be alert for
arrival aircraft coming from the opposite direction.
6.Recommended self-announce phraseologies:
It should be noted that aircraft operating to or from
another nearby airport may be making self-announce
broadcasts on the same UNICOM or MULTICOMfrequency. To help identify one airport from another,
the airport name should be spoken at the beginning
and end of each self-announce transmission.
(a)Inbound
EXAMPLE −
Strawn traffic, Apache Two Two Five Zulu, (position),
(altitude), (descending) or entering downwind/base/final(as appropriate) runway one seven full stop, touch−and−go, Strawn.
Strawn traffic Apache Two T wo Five Zulu clear of runway
one seven Strawn.
(b)Outbound
EXAMPLE −
Strawn traffic, Queen Air Seven One Five Five Bravo(location on airport) taxiing to runway two six Strawn.Strawn traffic, Queen Air Seven One Five Five Bravodeparting runway two six. Departing the pattern to the
(direction), climbing to (altitude) Strawn.
(c)Practice Instrument Approach
EXAMPLE −
Strawn traffic, Cessna Two One Four Three Quebec(position from airport) inbound descending through(altitude) practice (name of approach) approach runway
three five Strawn.
Strawn traffic, Cessna Two One Four Three Quebecpractice (type) approach completed or terminated runway
three five Strawn.
h. UNICOM Communications Procedures
1.In communicating with a UNICOM station,
the following practices will help reduce frequency
congestion, facilitate a better understanding of pilot
intentions, help identify the location of aircraft in the
traffic pattern, and enhance safety of flight:
(a)Select the correct UNICOM frequency.
(b)State the identification of the UNICOM
station you are calling in each transmission.
(c)Speak slowly and distinctly.
(d)Report approximately 10 miles from the
airport, reporting altitude, and state your aircraft type,
aircraft identification, location relative to the airport,
state whether landing or overflight, and request wind
information and runway in use.
(e)Report on downwind, base, and final
approach.
(f)Report leaving the runway.
2.Recommended UNICOM phraseologies:
(a)Inbound
PHRASEOLOGY −
FREDERICK UNICOM CESSNA EIGHT ZERO ONETANGO FOXTROT 10 MILES SOUTHEASTDESCENDING THROUGH (altitude) LANDINGFREDERICK, REQUEST WIND AND RUNWAY
INFORMATION FREDERICK.
FREDERICK TRAFFIC CESSNA EIGHT ZERO ONETANGO FOXTROT ENTERING DOWNWIND/BASE/
AIM 10/12/17
4−1−6 Services Available to PilotsFINAL (as appropriate) FOR RUNWAY ONE NINER (full
stop/touch −and−go) FREDERICK.
FREDERICK TRAFFIC CESSNA EIGHT ZERO ONETANGO FOXTROT CLEAR OF RUNWAY ONE NINER
FREDERICK.
(b)Outbound
PHRASEOLOGY −
FREDERICK UNICOM CESSNA EIGHT ZERO ONE
TANGO FOXTROT (location on airport) TAXIING TO
RUNWAY ONE NINER, REQUEST WIND AND TRAFFIC
INFORMATION FREDERICK. FREDERICK TRAFFIC CESSNA EIGHT ZERO ONETANGO FOXTROT DEP ARTING RUNWAY ONE NINER.
“REMAINING IN THE P ATTERN” OR “DEP ARTING
THE P ATTERN TO THE (direction) (as appropriate)”FREDERICK.
4−1−10. IFR Approaches/Ground Vehicle
Operations
a. IFR Approaches. When operating in accor-
dance with an IFR clearance and ATC approves a
change to the advisory frequency, make anexpeditious change to the CTAF and employ the
recommended traffic advisory procedures.
b. Ground Vehicle Operation. Airport ground
vehicles equipped with radios should monitor theCTAF frequency when operating on the airport
movement area and remain clear of runways/taxi-
ways being used by aircraft. Radio transmissions
from ground vehicles should be confined to
safety-related matters.
c. Radio Control of Airport Lighting Systems.
Whenever possible, the CTAF will be used to control
airport lighting systems at airports without operating
control towers. This eliminates the need for pilots tochange frequencies to turn the lights on and allows a
continuous listening watch on a single frequency. The
CTAF is published on the instrument approach chartand in other appropriate aeronautical information
publications. For further details concerning radio
controlled lights, see AC 150/5340 −27, Air−to−
Ground Radio Control of Airport Lighting Systems.4−1−11. Designated UNICOM/MULTICOM
Frequencies
Frequency use
a.The following listing depicts UNICOM and
MULTICOM frequency uses as designated by the
Federal Communications Commission (FCC). (See TBL 4 −1−2.)
TBL 4−1−2
Unicom/Multicom Frequency Usage
Use Frequency
Airports without an operating
control tower.122.700122.725
122.975123.000123.050
(MULTICOM FREQUENCY)
Activities of a temporary, seasonal,
emergency nature or search and
rescue, as well as, airports with notower, FSS, or UNICOM.122.900
(MULTICOM FREQUENCY)Forestry management and fire
suppression, fish and game
management and protection, andenvironmental monitoring andprotection.122.925
Airports with a control tower orFSS on airport. 122.950
NOTE−
1.In some areas of the country, frequency interference
may be encountered from nearby airports using the same
UNICOM frequency. Where there is a problem, UNICOM
operators are encouraged to develop a “least interfer-
ence” frequency assignment plan for airports concernedusing the frequencies designated for airports withoutoperating control towers. UNICOM licensees are
encouraged to apply for UNICOM 25 kHz spaced channel
frequencies. Due to the extremely limited number offrequencies with 50 kHz channel spacing, 25 kHz channel
spacing should be implemented. UNICOM licensees maythen r equest FCC to assign frequencies in accor dance with
the plan, which FCC will r eview and consider for appr oval.
2.Wind direction and runway information may not be
available on UNICOM frequency 122.950.
b.The following listing depicts other frequency
uses as designated by the Federal CommunicationsCommission (FCC). (See TBL 4 −1−3.)
AIM 10/12/17
4−1−7 Services Available to PilotsTBL 4−1−3
Other Frequency Usage Designated by FCC
Use Frequency
Air-to-air communication
(private fixed wing aircraft).122.750
Air-to-air communications(general aviation helicopters). 123.025
Aviation instruction, Glider, Hot Air
Balloon (not to be used for
advisory service) .123.300
4−1−12. Use of UNICOM for ATC Purposes
UNICOM service may be used for ATC purposes,
only under the following circumstances:
a.Revision to proposed departure time.
b.Takeoff, arrival, or flight plan cancellation
time.
c.ATC clearance, provided arrangements are
made between the ATC facility and the UNICOMlicensee to handle such messages.
4−1−13. Automatic Terminal Information
Service (ATIS)
a.ATIS is the continuous broadcast of recorded
noncontrol information in selected high activityterminal areas. Its purpose is to improve controller
effectiveness and to relieve frequency congestion by
automating the repetitive transmission of essentialbut routine information. The information is continu-
ously broadcast over a discrete VHF radio frequency
or the voice portion of a local NA VAID. Arrival ATIS
transmissions on a discrete VHF radio frequency are
engineered according to the individual facility
requirements, which would normally be a protectedservice volume of 20 NM to 60 NM from the ATIS
site and a maximum altitude of 25,000 feet AGL. In
the case of a departure ATIS, the protected servicevolume cannot exceed 5 NM and 100 feet AGL. At
most locations, ATIS signals may be received on the
surface of the airport, but local conditions may limitthe maximum ATIS reception distance and/or
altitude. Pilots are urged to cooperate in the ATIS
program as it relieves frequency congestion onapproach control, ground control, and local control
frequencies. The Chart Supplement U.S. indicates
airports for which ATIS is provided.b.ATIS information includes:
1.Airport/facility name
2.Phonetic letter code
3.Time of the latest weather sequence (UTC)
4.Weather information consisting of:
(a)Wind direction and velocity
(b)Visibility
(c)Obstructions to vision
(d)Present weather consisting of: sky condi-
tion, temperature, dew point, altimeter, a density
altitude advisory when appropriate, and otherpertinent remarks included in the official weather
observation
5.Instrument approach and runway in use.
The ceiling/sky condition, visibility, and obstructions
to vision may be omitted from the ATIS broadcast ifthe ceiling is above 5,000 feet and the visibility is
more than 5 miles. The departure runway will only be
given if different from the landing runway except atlocations having a separate ATIS for departure. The
broadcast may include the appropriate frequency and
instructions for VFR arrivals to make initial contactwith approach control. Pilots of aircraft arriving or
departing the terminal area can receive the
continuous ATIS broadcast at times when cockpitduties are least pressing and listen to as many repeats
as desired. ATIS broadcast must be updated upon the
receipt of any official hourly and special weather. Anew recording will also be made when there is a
change in other pertinent data such as runway change,
instrument approach in use, etc.
EXAMPLE −
Dulles International information Sierra. One four zero
zero zulu. Wind three five zero at eight. Visibility one zero.
Ceiling four thousand five hundred broken. Temperaturethree four. Dew point two eight. Altimeter three zero onezero. ILS runway one right approach in use. Departingrunway three zero. Advise on initial contact you have
information sierra.
c.Pilots should listen to ATIS broadcasts
whenever ATIS is in operation.
d.Pilots should notify controllers on initial
contact that they have received the ATIS broadcast by
repeating the alphabetical code word appended to the
broadcast.
AIM 10/12/17
4−1−8 Services Available to PilotsEXAMPLE −
“Information Sierra received.”
e.When a pilot acknowledges receipt of the ATIS
broadcast, controllers may omit those items con-
tained in the broadcast if they are current. Rapidlychanging conditions will be issued by ATC and the
ATIS will contain words as follows:
EXAMPLE −
“Latest ceiling/visibility/altimeter/wind/(other condi-tions) will be issued by approach control/tower.”
NOTE−
The absence of a sky condition or ceiling and/or visibility
on ATIS indicates a sky condition or ceiling of 5,000 feet or
above and visibility of 5 miles or more. A remark may bemade on the broadcast, “the weather is better than5000 and 5,” or the existing weather may be broadcast.
f.Controllers will issue pertinent information to
pilots who do not acknowledge receipt of a broadcast
or who acknowledge receipt of a broadcast which is
not current.
g.To serve frequency limited aircraft, FSSs are
equipped to transmit on the omnirange frequency at
most en route VORs used as A TIS voice outlets. Such
communication interrupts the ATIS broadcast. Pilots
of aircraft equipped to receive on other FSS
frequencies are encouraged to do so in order that these
override transmissions may be kept to an absolute
minimum.
h.While it is a good operating practice for pilots
to make use of the ATIS broadcast where it isavailable, some pilots use the phrase “have numbers”
in communications with the control tower. Use of this
phrase means that the pilot has received wind,runway, and altimeter information ONLY and the
tower does not have to repeat this information. It does
not indicate receipt of the ATIS broadcast and shouldnever be used for this purpose.
4−1−14. Automatic Flight Information
Service (AFIS) − Alaska FSSs Only
a.AFIS is the continuous broadcast of recorded
non−control information at airports in Alaska where
an FSS provides local airport advisory service. Its
purpose is to improve FSS specialist efficiency byreducing frequency congestion on the local airport
advisory frequency.
1.The AFIS broadcast will automate the
repetitive transmission of essential but routine
information (for example, weather, favored runway,braking action, airport NOT AMs, etc.). The informa-
tion is continuously broadcast over a discrete VHF
radio frequency (usually the ASOS frequency).
2.Use of AFIS is not mandatory, but pilots who
choose to utilize two −way radio communications
with the FSS are urged to listen to AFIS, as it relieves
frequency congestion on the local airport advisory
frequency. AFIS broadcasts are updated upon receipt
of any official hourly and special weather, andchanges in other pertinent data.
3.When a pilot acknowledges receipt of the
AFIS broadcast, FSS specialists may omit those
items contained in the broadcast if they are current.When rapidly changing conditions exist, the latest
ceiling, visibility, altimeter , wind or other conditions
may be omitted from the AFIS and will be issued bythe FSS specialist on the appro priate radio frequency.
EXAMPLE −
“Kotzebue information ALPHA. One six five five zulu.
Wind, two one zero at five; visibility two, fog; ceiling one
hundred overcast; temperature minus one two, dew pointminus one four; altimeter three one zero five. Altimeter inexcess of three one zero zero, high pressure altimetersetting procedures are in effect. Favored runway two six.
Weather in Kotzebue surface area is below V −F−R
minima− an ATC clearance is required. Contact
Kotzebue Radio on 123.6 for traffic advisories and advise
intentions. Notice to Airmen, Hotham NDB out of service.Transcribed Weather Broadcast out of service. Advise on
initial contact you have ALPHA.”
NOTE−
The absence of a sky condition or ceiling and/or visibilityon Alaska FSS AFIS indicates a sky condition or ceiling of5,000 feet or above and visibility of 5 miles or more. Aremark may be made on the broadcast, “the weather is
better than 5000 and 5.”
b.Pilots should listen to Alaska FSSs AFIS
broadcasts whenever Alaska FSSs AFIS is inoperation.
NOTE−
Some Alaska FSSs are open part time and/or seasonally.
c.Pilots should notify controllers on initial
contact that they have received the Alaska FSSs
AFIS broadcast by repeating the phonetic alphabeticletter appended to the broadcast.
EXAMPLE −
“Information Alpha received.”
d.While it is a good operating practice for pilots
to make use of the Alaska FSS AFIS broadcast where
it is available, some pilots use the phrase “have
AIM 10/12/17
4−1−9 Services Available to Pilotsnumbers” in communications with the FSS. Use of
this phrase means that the pilot has received wind,
runway, and altimeter information ONLY and the
Alaska FSS does not have to repeat this information.
It does not indicate receipt of the AFIS broadcast andshould never be used for this purpose.
4−1−15. Radar Traffic Information Service
This is a service provided by radar ATC facilities.
Pilots receiving this service are advised of any radar
target observed on the radar display which may be insuch proximity to the position of their aircraft or its
intended route of flight that it warrants their attention.
This service is not intended to relieve the pilot of theresponsibility for continual vigilance to see and avoid
other aircraft.
a. Purpose of the Service
1.The issuance of traffic information as
observed on a radar display is based on the principleof assisting and advising a pilot that a particular radar
target’s position and track indicates it may intersect or
pass in such proximity to that pilot’s intended flightpath that it warrants attention. This is to alert the pilot
to the traffic, to be on the lookout for it, and thereby
be in a better position to take appropriate actionshould the need arise.
2.Pilots are reminded that the surveillance radar
used by ATC does not provide altitude informationunless the aircraft is equipped with Mode C and the
radar facility is capable of displaying altitude
information.
b. Provisions of the Service
1.Many factors, such as limitations of the radar,
volume of traffic, controller workload and commu-
nications frequency congestion, could prevent the
controller from providing this service. Controllerspossess complete discretion for determining whether
they are able to provide or continue to provide this
service in a specific case. The controller’s reasonagainst providing or continuing to provide the service
in a particular case is not subject to question nor need
it be communicated to the pilot. In other words, theprovision of this service is entirely dependent upon
whether controllers believe they are in a position to
provide it. Traffic information is routinely providedto all aircraft operating on IFR flight plans except
when the pilot declines the service, or the pilot is
operating within Class A airspace. Traffic informa-tion may be provided to flights not operating on IFR
flight plans when requested by pilots of such flights.
NOTE−
Radar ATC facilities normally display and monitor bothprimary and secondary radar when it is available, exceptthat secondary radar may be used as the sole displaysource in Class A airspace, and under some cir cumstances
outside of Class A airspace (beyond primary coverage and
in en route areas where only secondary is available).Secondary radar may also be used outside Class Aairspace as the sole display source when the primary radar
is temporarily unusable or out of service. Pilots in contact
with the affected ATC facility are normally advised when
a temporary outage occurs; i.e., “primary radar out ofservice; traffic advisories available on transponderaircraft only.” This means simply that only the aircraftwhich have transponders installed and in use will be
depicted on A TC radar indicators when the primary radar
is temporarily out of service.
2.When receiving VFR radar advisory service,
pilots should monitor the assigned frequency at all
times. This is to preclude controllers’ concern for
radio failure or emer gency assistance to aircraft under
the controller’s jurisdiction. VFR radar advisory
service does not include vectors away from
conflicting traffic unless requested by the pilot. When
advisory service is no longer desired, advise the
controller before changing frequencies and then
change your transponder code to 1200, if applicable.
Pilots should also inform the controller when
changing VFR cruising altitude. Except in programs
where radar service is automatically terminated, thecontroller will advise the aircraft when radar is
terminated.
NOTE−
Participation by VFR pilots in formal programsimplemented at certain terminal locations constitutes pilot
request. This also applies to participating pilots at thoselocations where arriving VFR flights are encouraged to
make their first contact with the tower on the approach
control frequency.
c. Issuance of Traffic Information. Traffic
information will include the following concerning a
target which may constitute traffic for an aircraft that
is:
1. Radar identified
(a)Azimuth from the aircraft in terms of the
12 hour clock, or
(b)When rapidly maneuvering civil test or
military aircraft prevent accurate issuance of traffic
as in (a) above, specify the direction from an aircraft’s
AIM 10/12/17
4−1−10 Services Available to Pilotsposition in terms of the eight cardinal compass points
(N, NE, E, SE, S, SW, W, NW). This method must be
terminated at the pilot’s request.
(c)Distance from the aircraft in nautical
miles;
(d)Direction in which the target is proceed-
ing; and
(e)Type of aircraft and altitude if known.
EXAMPLE −
Traffic 10 o’clock, 3 miles, west-bound (type aircraft andaltitude, if known, of the observed traffic). The altitude may
be known, by means of Mode C, but not verified with the
pilot for accuracy. (To be valid for separation purposes by
ATC, the accuracy of Mode C readouts must be verified.This is usually accomplished upon initial entry into theradar system by a comparison of the readout to pilot stated
altitude, or the field elevation in the case of continuous
readout being received from an aircraft on the airport.)
When necessary to issue traffic advisories containingunverified altitude information, the controller will issue the
advisory in the same manner as if it were verified due to the
accuracy of these readouts. The pilot may upon receipt of
traffic information, request a vector (heading) to avoid
such traffic. The vector will be provided to the extentpossible as determined by the controller provided theaircraft to be vectored is within the airspace under thejurisdiction of the controller.
2. Not radar identified
(a)Distance and direction with respect to a
fix;
(b)Direction in which the target is proceed-
ing; and
(c)Type of aircraft and altitude if known.
EXAMPLE −
Traffic 8 miles south of the airport northeastbound, (typeaircraft and altitude if known).
d.The examples depicted in the following figures
point out the possible error in the position of this
traffic when it is necessary for a pilot to apply driftcorrection to maintain this track. This error could also
occur in the event a change in course is made at the
time radar traffic information is issued.FIG 4−1−1
Induced Error in Position of Traffic
TRACK
(A) (B)WIND
TRACK
EXAMPLE −
In FIG 4−1−1 traffic information would be issued to the
pilot of aircraft “A” as 12 o’clock. The actual position ofthe traffic as seen by the pilot of aircraft “A” would be2 o’clock. T raffic information issued to aircraft “B” would
also be given as 12 o’clock, but in this case, the pilot of “B”
would see the traffic at 10 o’clock.
FIG 4−1−2
Induced Error in Position of Traffic
TRACK(C)(D)WINDTRACK
EXAMPLE −
In FIG 4−1−2 traffic information would be issued to the
pilot of air craft “C” as 2 o’clock. The actual position of the
traffic as seen by the pilot of aircraft “C” would be3 o’clock. T raffic information issued to aircraft “D” would
be at an 11 o’clock position. Since it is not necessary for the
pilot of aircraft “D” to apply wind correction (crab) to
remain on track, the actual position of the traffic issued
would be correct. Since the radar controller can onlyobserve air craft track (course) on the radar display, traffic
advisories are issued accordingly, and pilots should givedue consideration to this fact when looking for reported
traffic.
4−1−16. Safety Alert
A safety alert will be issued to pilots of aircraft being
controlled by ATC if the controller is aware the
aircraft is at an altitude which, in the controller’s
judgment, places the aircraft in unsafe proximity toterrain, obstructions or other aircraft. The provision
of this service is contingent upon the capability of the
controller to have an awareness of a situationinvolving unsafe proximity to terrain, obstructions
and uncontrolled aircraft. The issuance of a safety
alert cannot be mandated, but it can be expected on a
AIM 10/12/17
4−1−11 Services Available to Pilotsreasonable, though intermittent basis. Once the alert
is issued, it is solely the pilot’s prerogative to
determine what course of action, if any, to take. This
procedure is intended for use in time critical
situations where aircraft safety is in question.Noncritical situations should be handled via the
normal traffic alert procedures.
a. Terrain or Obstruction Alert
1.Controllers will immediately issue an alert to
the pilot of an aircraft under their control when theyrecognize that the aircraft is at an altitude which, in
their judgment, may be in an unsafe proximity to
terrain/obstructions. The primary method of detect-
ing unsafe proximity is through Mode C automatic
altitude reports.
EXAMPLE −
Low altitude alert Cessna Three Four Juliet, check youraltitude immediately. And if the aircraft is not yet on finalapproach, the MVA (MEA/MIA/MOCA) in your area is six
thousand.
2.Terminal Automated Radar T erminal System
(ARTS) IIIA, Common ARTS (to include ARTS IIIEand ARTS IIE) (CARTS), Micro En Route
Automated Radar Tracking System (MEARTS), and
Standard Terminal Automation Replacement System
(STARS) facilities have an automated function
which, if operating, alerts controllers when a tracked
Mode C equipped aircraft under their control is below
or is predicted to be below a predetermined minimum
safe altitude. This function, called Minimum Safe
Altitude Warning (MSAW), is designed solely as acontroller aid in detecting potentially unsafe aircraft
proximity to terrain/obstructions. The ARTS IIIA,
CARTS, MEARTS, and STARS facility will, when
MSAW is operating, provide MSAW monitoring for
all aircraft with an operating Mode C altitudeencoding transponder that are tracked by the system
and are:
(a)Operating on an IFR flight plan; or
(b)Operating VFR and have requested
MSAW monitoring.
3.Terminal AN/TPX −42A (number beacon
decoder system) facilities have an automatedfunction called Low Altitude Alert System (LAAS).
Although not as sophisticated as MSAW, LAAS
alerts the controller when a Mode C transponderequipped aircraft operating on an IFR flight plan is
below a predetermined minimum safe altitude.
NOTE−
Pilots operating VFR may request MSAW or LAAS
monitoring if their aircraft are equipped with Mode C
transponders.
EXAMPLE −
Apache Three Three Papa request MSAW/LAAS.
b. Aircraft Conflict Alert.
1.Controllers will immediately issue an alert to
the pilot of an aircraft under their control if they are
aware of another aircraft which is not under their
control, at an altitude which, in the controller’s
judgment, places both aircraft in unsafe proximity to
each other. With the alert, when feasible, the
controller will offer the pilot the position of the traffic
if time permits and an alternate course(s) of action.Any alternate course(s) of action the controller may
recommend to the pilot will be predicated only on
other traffic being worked by the controller.
EXAMPLE −
American Three, traffic alert, (position of traffic, if timepermits), advise you turn right/left heading (degrees)and/or climb/descend to (altitude) immediately.
4−1−17. Radar Assistance to VFR Aircraft
a.Radar equipped FAA ATC facilities provide
radar assistance and navigation service (vectors) to
VFR aircraft provided the aircraft can communicatewith the facility, are within radar coverage, and can be
radar identified.
b.Pilots should clearly understand that authoriza-
tion to proceed in accordance with such radar
navigational assistance does not constitute authoriza-
tion for the pilot to violate CFRs. In ef fect, assistance
provided is on the basis that navigational guidance
information issued is advisory in nature and the job of
flying the aircraft safely, remains with the pilot.
c.In many cases, controllers will be unable to
determine if flight into instrument conditions will
result from their instructions. To avoid possible
hazards resulting from being vectored into IFRconditions, pilots should keep controllers advised of
the weather conditions in which they are operating
and along the course ahead.
d.Radar navigation assistance (vectors) may be
initiated by the controller when one of the following
conditions exist:
AIM 10/12/17
4−1−12 Services Available to Pilots1.The controller suggests the vector and the
pilot concurs.
2.A special program has been established and
vectoring service has been advertised.
3.In the controller’s judgment the vector is
necessary for air safety.
e.Radar navigation assistance (vectors) and other
radar derived information may be provided in
response to pilot requests. Many factors, such as
limitations of radar, volume of traffic, communica-tions frequency, congestion, and controller workload
could prevent the controller from providing it.
Controllers have complete discretion for determining
if they are able to provide the service in a particular
case. Their decision not to provide the service in a
particular case is not subject to question.
4−1−18. Terminal Radar Services for VFR
Aircraft
a. Basic Radar Service:
1.In addition to the use of radar for the control
of IFR aircraft, all commissioned radar facilities
provide the following basic radar services for VFRaircraft:
(a)Safety alerts.
(b)Traffic advisories.
(c)Limited radar vectoring (on a workload
permitting basis).
(d)Sequencing at locations where proce-
dures have been established for this purpose and/or
when covered by a Letter of Agreement.
NOTE−
When the stage services were developed, two basic radar
services (traffic advisories and limited vectoring) wereidentified as “Stage I.” This definition became unneces-sary and the term “Stage I” was eliminated from use. Theterm “Stage II” has been eliminated in conjunction with
the airspace reclassification, and sequencing services to
locations with local pr ocedures and/or letters of agr eement
to provide this service have been included in basic servicesto VFR aircraft. These basic services will still be provided
by all terminal radar facilities whether they include
Class B, Class C, Class D or Class E airspace. “Stage III”
services have been replaced with “Class B” and “TRSA”service where applicable.2.Vectoring service may be provided when
requested by the pilot or with pilot concurrence when
suggested by ATC.
3.Pilots of arriving aircraft should contact
approach control on the publicized frequency and
give their position, altitude, aircraft call sign, typeaircraft, radar beacon code (if transponder equipped),
destination, and request traffic information.
4.Approach control will issue wind and
runway, except when the pilot states “have numbers”
or this information is contained in the A TIS broadcast
and the pilot states that the current A TIS information
has been received. Traffic informat ion is provided on
a workload permitting basis. Approach control will
specify the time or place at which the pilot is to
contact the tower on local control frequency for
further landing information. Radar service isautomatically terminated and the aircraft need not be
advised of termination when an arriving VFR aircraft
receiving radar services to a tower −controlled airport
where basic radar service is provided has landed, or
to all other airports, is instructed to change to tower
or advisory frequency. (See FAA Order JO 7110.65,
Air Traffic Control, Paragraph 5 −1−13, Radar
Service Termination.)
5.Sequencing for VFR aircraft is available at
certain terminal locations (see locations listed in the
Chart Supplement U.S.). The purpose of the service
is to adjust the flow of arriving VFR and IFR aircraftinto the traffic pattern in a safe and orderly manner
and to provide radar traffic information to departing
VFR aircraft. Pilot participation is urged but is notmandatory. Traffic information is provided on a
workload permitting basis. Standard radar separation
between VFR or between VFR and IFR aircraft is not
provided.
(a)Pilots of arriving VFR aircraft should
initiate radio contact on the publicized frequencywith approach control when approximately 25 miles
from the airport at which sequencing services are
being provided. On initial contact by VFR aircraft,approach control will assume that sequencing service
is requested. After radar contact is established, the
pilot may use pilot navigation to enter the trafficpattern or, depending on traffic conditions, approach
control may provide the pilot with routings or vectors
necessary for proper sequencing with other partici-pating VFR and IFR traffic en route to the airport.
When a flight is positioned behind a preceding
aircraft and the pilot reports having that aircraft in
AIM 10/12/17
4−1−13 Services Available to Pilotssight, the pilot will be instructed to follow the
preceding aircraft. THE ATC INSTRUCTION TO
FOLLOW THE PRECEDING AIRCRAFT DOES
NOT AUTHORIZE THE PILOT TO COMPLY
WITH ANY ATC CLEARANCE OR INSTRUC-TION ISSUED TO THE PRECEDING AIRCRAFT.
If other “nonparticipating” or “local” aircraft are in
the traffic pattern, the tower will issue a landingsequence. If an arriving aircraft does not want radar
service, the pilot should state “NEGATIVE RADAR
SERVICE” or make a similar comment, on initialcontact with approach control.
(b)Pilots of departing VFR aircraft are
encouraged to request radar traffic information by
notifying ground control on initial contact with their
request and proposed direction of flight.
EXAMPLE −
Xray gr ound control, November One Eight Six, Cessna One
Seventy T wo, ready to taxi, VFR southbound at 2,500, have
information bravo and request radar traffic information.
NOTE−
Following takeoff, the tower will advise when to contact
departure control.
(c)Pilots of aircraft transiting the area and in
radar contact/communication with approach control
will receive traffic information on a controllerworkload permitting basis. Pilots of such aircraft
should give their position, altitude, aircraft call sign,
aircraft type, radar beacon code (if transponderequipped), destination, and/or route of flight.
b. TRSA Service (Radar Sequencing and
Separation Service for VFR Aircraft in a TRSA).
1.This service has been implemented at certain
terminal locations. The service is advertised in the
Chart Supplement U.S. The purpose of this service is
to provide separation between all participating VFRaircraft and all IFR aircraft operating within the
airspace defined as the Terminal Radar Service Area
(TRSA). Pilot participation is urged but is notmandatory.
2.If any aircraft does not want the service, the
pilot should state “NEGATIVE TRSA SERVICE” or
make a similar comment, on initial contact with
approach control or ground control, as appropriate.
3.TRSAs are depicted on sectional aeronautical
charts and listed in the Chart Supplement U.S.4.While operating within a TRSA, pilots are
provided TRSA service and separation as prescribed
in this paragraph. In the event of a radar outage,
separation and sequencing of VFR aircraft will be
suspended as this service is dependent on radar. Thepilot will be advised that the service is not available
and issued wind, runway information, and the time or
place to contact the tower. Traf fic information will be
provided on a workload permitting basis.
5.Visual separation is used when prevailing
conditions permit and it will be applied as follows:
(a)When a VFR flight is positioned behind a
preceding aircraft and the pilot reports having thataircraft in sight, the pilot will be instructed by ATC to
follow the preceding aircraft. Radar service will be
continued to the runway. THE ATC INSTRUCTION
TO FOLLOW THE PRECEDING AIRCRAFT
DOES NOT AUTHORIZE THE PILOT TO
COMPLY WITH ANY ATC CLEARANCE ORINSTRUCTION ISSUED TO THE PRECEDING
AIRCRAFT.
(b)If other “nonparticipating” or “local”
aircraft are in the traffic pattern, the tower will issuea landing sequence.
(c)Departing VFR aircraft may be asked if
they can visually follow a preceding departure out of
the TRSA. The pilot will be instructed to follow the
other aircraft provided that the pilot can maintain
visual contact with that aircraft.
6.VFR aircraft will be separated from VFR/IFR
aircraft by one of the following:
(a)500 feet vertical separation.
(b)Visual separation.
(c)Target resolution (a process to ensure that
correlated radar targets do not touch).
7.Participating pilots operating VFR in a
TRSA:
(a)Must maintain an altitude when assigned
by ATC unless the altitude assignment is to maintain
at or below a specified altitude. ATC may assign
altitudes for separation that do not conform to14 CFR Section 91.159. When the altitude assign-
ment is no longer needed for separation or when
leaving the TRSA, the instruction will be broadcast,“RESUME APPROPRIATE VFR ALTITUDES.”
Pilots must then return to an altitude that conforms to
14 CFR Section 91.159 as soon as practicable.
AIM 10/12/17
4−1−14 Services Available to Pilots(b)When not assigned an altitude, the pilot
should coordinate with ATC prior to any altitude
change.
8.Within the TRSA, traffic information on
observed but unidentified targets will, to the extent
possible, be provided to all IFR and participatingVFR aircraft. The pilot will be vectored upon request
to avoid the observed traffic, provided the aircraft to
be vectored is within the airspace under thejurisdiction of the controller.
9.Departing aircraft should inform ATC of their
intended destination and/or route of flight andproposed cruising altitude.
10.ATC will normally advise participating
VFR aircraft when leaving the geographical limits of
the TRSA. Radar service is not automaticallyterminated with this advisory unless specifically
stated by the controller.
c. Class C Service. This service provides, in
addition to basic radar service, approved separation
between IFR and VFR aircraft, and sequencing of
VFR arrivals to the primary airport.
d. Class B Service. This service provides, in
addition to basic radar service, approved separation
of aircraft based on IFR, VFR, and/or weight, and
sequencing of VFR arrivals to the primary airport(s)
e. PILOT RESPONSIBILITY. THESE SER-
VICES ARE NOT TO BE INTERPRETED AS
RELIEVING PILOTS OF THEIR RESPONSIBILI-
TIES TO SEE AND A VOID OTHER TRAFFIC
OPERATING IN BASIC VFR WEATHER CONDI-
TIONS, TO ADJUST THEIR OPERATIONS ANDFLIGHT PATH AS NECESSARY TO PRECLUDE
SERIOUS W AKE ENCOUNTERS, TO MAINTAIN
APPROPRIATE TERRAIN AND OBSTRUCTIONCLEARANCE, OR TO REMAIN IN WEATHER
CONDITIONS EQUAL TO OR BETTER THAN
THE MINIMUMS REQUIRED BY 14 CFRSECTION 91.155. WHENEVER COMPLIANCE
WITH AN ASSIGNED ROUTE, HEADING
AND/OR ALTITUDE IS LIKELY TO COMPRO-MISE PILOT RESPONSIBILITY RESPECTING
TERRAIN AND OBSTRUCTION CLEARANCE,
VORTEX EXPOSURE, AND WEATHER MINI-MUMS, APPROACH CONTROL SHOULD BE SO
ADVISED AND A REVISED CLEARANCE OR
INSTRUCTION OBTAINED
.f.ATC services for VFR aircraft participating in
terminal radar services are dependent on ATC radar.
Services for VFR aircraft are not available during
periods of a radar outage and are limited during
CENRAP operations. The pilot will be advised when
VFR services are limited or not available.
NOTE−
Class B and Class C airspace are areas of regulatedairspace. The absence of ATC radar does not negate the
requirement of an ATC clearance to enter Class B airspace
or two way radio contact with ATC to enter Class Cairspace.
4−1−19. Tower En Route Control (TEC)
a.TEC is an ATC program to provide a service to
aircraft proceeding to and from metropolitan areas. It
links designated Approach Control Areas by a
network of identified routes made up of the existing
airway structure of the National Airspace System.The FAA initiated an expanded TEC program to
include as many facilities as possible. The program’s
intent is to provide an overflow resource in the lowaltitude system which would enhance ATC services.
A few facilities have historically allowed turbojets to
proceed between certain city pairs, such asMilwaukee and Chicago, via tower en route and these
locations may continue this service. However, the
expanded TEC program will be applied, generally,for nonturbojet aircraft operating at and below
10,000 feet. The program is entirely within the
approach control airspace of multiple terminalfacilities. Essentially, it is for relatively short flights.
Participating pilots are encouraged to use TEC for
flights of two hours duration or less. If longer flights
are planned, extensive coordination may be required
within the multiple complex which could result in
unanticipated delays.
b.Pilots requesting TEC are subject to the same
delay factor at the destination airport as other aircraft
in the A TC system. In addition, departure and en routedelays may occur depending upon individual facility
workload. When a major metropolitan airport is
incurring significant delays, pilots in the TEC
program may want to consider an alternative airport
experiencing no delay.
c.There are no unique requirements upon pilots to
use the TEC program. Normal flight plan filing
procedures will ensure proper flight plan processing.
Pilots should include the acronym “TEC” in the
AIM 10/12/17
4−1−15 Services Available to Pilotsremarks section of the flight plan when requesting
tower en route control.
d.All approach controls in the system may not
operate up to the maximum TEC altitude of
10,000 feet. IFR flight may be planned to any
satellite airport in proximity to the major primaryairport via the same routing.
4−1−20. Transponder Operation
a. General
1.Pilots should be aware that proper application
of transponder operating procedures will provide
both VFR and IFR aircraft with a higher degree ofsafety while operating on the ground and airborne.
Transponders with altitude reporting mode turned
ON (Mode C or S) substantially increase thecapability of surveillance systems to see an aircraft,
thus providing the Air Traffic Controller increased
situational awareness and the ability to identifypotential traffic conflicts. Even VFR pilots who are
not in contact with ATC will be afforded greater
protection from IFR aircraft and VFR aircraft whichare receiving traffic advisories. Nevertheless, pilots
should never relax their visual scanning for other
aircraft.
2.Air Traffic Control Radar Beacon System
(ATCRBS) is similar to and compatible with military
coded radar beacon equipment. Civil Mode A isidentical to military Mode 3.
3. Transponder and ADS-B operations on the
ground . Civil and military aircraft should operate
with the transponder in the altitude reporting mode(consult the aircraft’s flight manual to determine the
specific transponder position to enable altitude
reporting) and ADS-B Out transmissions enabled (if
equipped) at all airports, any time the aircraft is
positioned on any portion of an airport movement
area. This includes all defined taxiways and runways.
Pilots must pay particular attention to ATIS and
airport diagram notations, General Notes (included
on airport charts), and comply with directionspertaining to transponder and ADS-B usage.
Generally, these directions are:
(a)Departures. Select the transponder mode
which allows altitude reporting and enable ADS-B (if
equipped) during pushback or taxi-out from parking
spot. Select TA or TA/RA (if equipped with TCAS)
when taking the active runway.(b)Arrivals. Maintain transponder to the
altitude reporting mode or if TCAS-equipped (TA or
TA/RA), select the transponder to altitude reporting
mode. Maintain ADS-B Out transmissions (if
equipped) after clearing the active runway. SelectSTBY or OFF for transponder and ADS-B (if
equipped) upon arriving at the aircraft’s parking spot
or gate.
4. Transponder and ADS-B Operations in
the Air. EACH PILOT OPERATING AN AIR-
CRAFT EQUIPPED WITH AN OPERABLE ATC
TRANSPONDER, MAINTAINED IN ACCORD-
ANCE WITH 14 CFR SECTION 91.413 OR ADS-B
TRANSMITTER, MUST OPERATE THE
TRANSPONDER/TRANSMITTER, INCLUDING
MODE C/S IF INSTALLED, ON THE APPROPRI-ATE MODE 3/A CODE OR AS ASSIGNED BY
ATC. EACH PERSON OPERATING AN AIR-
CRAFT EQUIPPED WITH ADS-B OUT MUSTOPERATE THIS EQUIPMENT IN THE TRANS-
MIT MODE AT ALL TIMES WHILE AIRBORNE
UNLESS OTHERWISE REQUESTED BY ATC.
5.A pilot on an IFR flight who elects to cancel
the IFR flight plan prior to reaching destination,should adjust the transponder according to VFR
operations.
6.If entering a U.S. OFFSHORE AIRSPACE
AREA from outside the U.S., the pilot should advise
on first radio contact with a U.S. radar ATC facility
that such equipment is available by adding
“transponder” to the aircraft identification.
7.It should be noted by all users of ATC
transponders and ADS −B Out systems that the
surveillance coverage they can expect is limited to
“line of sight” with ground radar and ADS −B radio
sites. Low altitude or aircraft antenna shielding by the
aircraft itself may result in reduced range or loss of
aircraft contact. Surveillance coverage can be
improved by climbing to a higher altitude.
NOTE−
Pilots of aircraft equipped with ADS −B should refer to
AIM, Automatic Dependent Surveillance − Broadcast
Services, Paragraph 4 −5−7 , for a complete description of
operating limitations and procedures.
b. Transponder Code Designation
1.For A TC to utilize one or a combination of the
4096 discrete codes FOUR DIGIT CODE DES-
IGNATION will be used; for example, code 2100 will
be expressed as TWO ONE ZERO ZERO. Due to the
AIM 10/12/17
4−1−16 Services Available to Pilotsoperational characteristics of the rapidly expanding
automated ATC system, THE LAST TWO DIGITS
OF THE SELECTED TRANSPONDER CODE
SHOULD ALWAYS READ “00” UNLESS SPECIF-
ICALLY REQUESTED BY ATC TO BEOTHERWISE.
c. Automatic Altitude Reporting (Mode C)
1.Some transponders are equipped with a
Mode C automatic altitude reporting capability. Thissystem converts aircraft altitude in 100 foot
increments to coded digital information which is
transmitted together with Mode C framing pulses tothe interrogating radar facility. The manner in which
transponder panels are designed differs, therefore, a
pilot should be thoroughly familiar with the operation
of the transponder so that ATC may realize its full
capabilities.
2.Adjust transponder to reply on the Mode A/3
code specified by ATC and, if equipped, to reply on
Mode C with altitude reporting capability activatedunless deactivation is directed by ATC or unless the
installed aircraft equipment has not been tested and
calibrated as required by 14 CFR Section 91.217. Ifdeactivation is required by ATC, turn off the altitude
reporting feature of your transponder. An instruction
by ATC to “STOP ALTITUDE SQUAWK, ALTI-
TUDE DIFFERS (number of feet) FEET,” may be an
indication that your transponder is transmittingincorrect altitude information or that you have an
incorrect altimeter setting. While an incorrect
altimeter setting has no effect on the Mode C altitude
information transmitted by your transponder (trans-
ponders are preset at 29.92), it would cause you to fly
at an actual altitude different from your assignedaltitude. When a controller indicates that an altitude
readout is invalid, the pilot should initiate a check to
verify that the aircraft altimeter is set correctly.
3.Pilots of aircraft with operating Mode C
altitude reporting transponders should report exactaltitude or flight level to the nearest hundred foot
increment when establishing initial contact with an
ATC facility. Exact altitude or flight level reports oninitial contact provide ATC with information that is
required prior to using Mode C altitude information
for separation purposes. This will significantlyreduce altitude verification requests.
d. Transponder IDENT Feature1.The transponder must be operated only as
specified by A TC. Activate the “IDENT” feature only
upon request of the ATC controller.
e. Code Changes
1.When making routine code changes, pilots
should avoid inadvertent selection of Codes 7500,7600 or 7700 thereby causing momentary false
alarms at automated ground facilities. For example,
when switching from Code 2700 to Code 7200,switch first to 2200 then to 7200, NOT to 7700 and
then 7200. This procedure applies to nondiscrete
Code 7500 and all discrete codes in the 7600 and 7700
series (i.e., 7600 −7677, 7700 −7777) which will
trigger special indicators in automated facilities.
Only nondiscrete Code 7500 will be decoded as thehijack code.
2.Under no circumstances should a pilot of a
civil aircraft operate the transponder on Code 7777.
This code is reserved for military interceptor
operations.
3.Military pilots operating VFR or IFR within
restricted/warning areas should adjust their trans-ponders to Code 4000 unless another code has been
assigned by ATC.
f. Mode C Transponder Requirements
1.Specific details concerning requirements to
carry and operate Mode C transponders, as well as
exceptions and ATC authorized deviations from therequirements are found in 14 CFR Section 91.215 and
14 CFR Section 99.12.
2.In general, the CFRs require aircraft to be
equipped with Mode C transponders when operating:
(a)At or above 10,000 feet MSL over the
48 contiguous states or the District of Columbia,
excluding that airspace below 2,500 feet AGL;
(b)Within 30 miles of a Class B airspace
primary airport, below 10,000 feet MSL. Balloons,gliders, and aircraft not equipped with an engine
driven electrical system are excepted from the above
requirements when operating below the floor of
Class A airspace and/or; outside of a Class B airspace
and below the ceiling of the Class B airspace (or
10,000 feet MSL, whichever is lower);
(c)Within and above all Class C airspace, up
to 10,000 feet MSL;
(d)Within 10 miles of certain designated
airports, excluding that airspace which is both outside
AIM 10/12/17
4−1−17 Services Available to Pilotsthe Class D surface area and below 1,200 feet AGL.
Balloons, gliders and aircraft not equipped with an
engine driven electrical system are excepted from this
requirement.
3.14 CFR Section 99.13 requires all aircraft
flying into, within, or across the contiguous U.S.
ADIZ be equipped with a Mode C or Mode S
transponder. Balloons, gliders and aircraft notequipped with an engine driven electrical system are
excepted from this requirement.
4.Pilots must ensure that their aircraft trans-
ponder is operating on an appropriate ATC assigned
VFR/IFR code and Mode C when operating in such
airspace. If in doubt about the operational status ofeither feature of your transponder while airborne,
contact the nearest ATC facility or FSS and they will
advise you what facility you should contact fordetermining the status of your equipment.
5.In-flight requests for “immediate” deviation
from the transponder requirement may be approved
by controllers only when the flight will continue IFR
or when weather conditions prevent VFR descent andcontinued VFR flight in airspace not affected by the
CFRs. All other requests for deviation should be
made by contacting the nearest Flight Service orAir Traffic facility in person or by telephone. The
nearest ARTCC will normally be the controlling
agency and is responsible for coordinating requestsinvolving deviations in other ARTCC areas.
g. Transponder Operation Under Visual Flight
Rules (VFR)
1.Unless otherwise instructed by an ATC
facility, adjust transponder to reply on Mode 3/ACode 1200 regardless of altitude.
NOTE−
1.Aircraft not in contact with an ATC facility may squawk
1255 in lieu of 1200 while en route to, from, or within the
designated fire fighting area(s).
2.VFR aircraft which fly authorized SAR missions for the
USAF or USCG may be advised to squawk 1277 in lieu of1200 while en route to, from , or within the designated
search area.
3.Gliders not in contact with an ATC facility should
squawk 1202 in lieu of 1200.
REFERENCE −
F AA Order JO 7110.66, National Beacon Code Allocation Plan .
2.Adjust transponder to reply on Mode C, with
altitude reporting capability activated if the aircraft isso equipped, unless deactivation is directed by ATC
or unless the installed equipment has not been tested
and calibrated as required by 14 CFR Section 91.217.
If deactivation is required and your transponder is so
designed, turn off the altitude reporting switch andcontinue to transmit Mode C framing pulses. If this
capability does not exist, turn off Mode C.
h. Radar Beacon Phraseology
Air traffic controllers, both civil and military, will use
the following phraseology when referring to
operation of the Air Traffic Control Radar Beacon
System (A TCRBS). Instructions by ATC refer only to
Mode A/3 or Mode C operation and do not affect the
operation of the transponder on other Modes.
1. SQUAWK (number). Operate radar beacon
transponder on designated code in Mode A/3.
2. IDENT. Engage the “IDENT” feature (mili-
tary I/P) of the transponder.
3. SQUAWK (number) and IDENT. Operate
transponder on specified code in Mode A/3 andengage the “IDENT” (military I/P) feature.
4. SQUAWK STANDBY. Switch transponder
to standby position.
5. SQUAWK LOW/NORMAL. Operate
transponder on low or normal sensitivity as specified.
Transponder is operated in “NORMAL” position
unless ATC specifies “LOW” (“ON” is used insteadof “NORMAL” as a master control label on some
types of transponders.)
6. SQUAWK ALTITUDE. Activate Mode C
with automatic altitude reporting.
7. STOP ALTITUDE SQUAWK. Turn off
altitude reporting switch and continue transmitting
Mode C framing pulses. If your equipment does nothave this capability, turn off Mode C.
8. STOP SQUAWK (mode in use). Switch off
specified mode. (Used for military aircraft when the
controller is unaware of military service require-
ments for the aircraft to continue operation on another
Mode.)
9. STOP SQUAWK. Switch off transponder.
10. SQUAWK MAYDAY. Operate transpond-
er in the emergency position (Mode A Code 7700 for
civil transponder. Mode 3 Code 7700 and emer gency
feature for military transponder.)
AIM 10/12/17
4−1−18 Services Available to Pilots11. SQUAWK VFR. Operate radar beacon
transponder on Code 1200 in the Mode A/3, or other
appropriate VFR code.
4−1−21. Airport Reservation Operations
and Special Traffic Management Programs
This section describes procedures for obtaining
required airport reservations at airports designated by
the FAA and for airports operating under SpecialTraffic Management Programs.
a. Slot Controlled Airports.
1.The FAA may adopt rules to require advance
operations for unscheduled operations at certain
airports. In addition to the information in the rules
adopted by the FAA, a listing of the airports andrelevant information will be maintained on the FAA
website listed below.
2.The FAA has established an Airport
Reservation Office (ARO) to receive and process
reservations for unscheduled flights at the slot
controlled airports. The ARO uses the Enhanced
Computer V oice Reservation System (e −CVRS) to
allocate reservations. Reservations will be available
beginning 72 hours in advance of the operation at the
slot controlled airport. Standby lists are not
maintained. Flights with declared emergencies do not
require reservations. Refer to the website or
touch− tone phone interface for the current listing of
slot controlled airports, limitations, and reservationprocedures.
NOTE−
The web interface/telephone numbers to obtain a
reservation for unscheduled operations at a slot contr olled
airport are:
1. http://www.fly.faa.gov/ecvrs.2. Touch− tone: 1− 800− 875− 9694
3. Trouble number: 540− 422− 4246.
3.For more detailed information on operations
and reservation procedures at a Slot Controlled
Airport, please see 14 CFR Part 93, Subpart K – High
Density Traffic Airports.b. Special Traffic Management Programs
(STMP).
1.Special procedures may be established when
a location requires special traffic handling toaccommodate above normal traffic demand (for
example, the Indianapolis 500, Super Bowl, etc.) or
reduced airport capacity (for example, airport
runway/taxiway closures for airport construction).
The special procedures may remain in effect until the
problem has been resolved or until local traffic
management procedures can handle the situation and
a need for special handling no longer exists.
2.There will be two methods available for
obtaining slot reservations through theATCSCC: the web interface and the touch −tone
interface. If these methods are used, a NOTAM will
be issued relaying the website address and toll free
telephone number. Be sure to check current
NOTAMs to determine: what airports are included
in the STMP, the dates and times reservations arerequired, the time limits for reservation requests, the
point of contact for reservations, and any otherinstructions.
NOTE−
The telephone numbers/web address to obtain a STMP slot
are:
1.Touch− tone interface: 1 −800− 875− 9755.
2. Web interface: www.fly.faa.gov.
3. Trouble number: 540− 422− 4246.
c.Users may contact the ARO at (540) 422 −4246
if they have a problem making a reservation or havea question concerning the slot controlled airport/
STMP regulations or procedures.
d. Making Reservations.
1. Internet Users. Detailed information and
User Instruction Guides for using the Web interface
to the reservation systems are available on thewebsites for the slot controlled airports (e −CVRS),
http://www.fly.faa.gov/ecvrs; and STMPs(e−STMP), http://www.fly.faa.gov/estmp.
AIM 10/12/17
4−1−19 Services Available to Pilots2. Telephone users. When using the telephone
to make a reservation, you are prompted for input of
information about what you wish to do. All input is
accomplished using the keypad on the telephone. The
only pro blem with a telephone is that most keys have
a letter and number associated with them. When the
system asks for a date or time, it is expecting an input
of numbers. A problem arises when entering anaircraft call sign or tail number. The system does not
detect if you are entering a letter (alpha character) or
a number. Therefore, when entering an aircraft callsign or tail number two keys are used to represent
each letter or number. When entering a number,
precede the number you wish by the number 0 (zero)
i.e., 01, 02, 03, 04, . . .. If you wish to enter a letter, first
press the key on which the letter appears and thenpress 1, 2, or 3, depending upon whether the letter you
desire is the first, second, or third letter on that key.
For example, to enter the letter “N” first press the
“6” key because “N” is on that key, then press the
“2” key because the letter “N” is the second letter onthe “6” key. Since there are no keys for the letters “Q”
and “Z” e −CVRS pretends they are on the number
“1” key. Therefore, to enter the letter “Q”, press 11,and to enter the letter “Z” press 12.
NOTE−
Users are reminded to enter the “N” character with theirtail numbers. (See TBL 4 −1−4.)
3.For additional helpful key entries, see
TBL 4−1−5.
TBL 4−1−4
Codes for Call Sign/Tail Number Input
Codes for Call Sign/Tail Number Input Only
A−21 J−51 S−73 1-01
B−22 K−52 T−81 2−02
C−23 L−53 U−82 3−03
D−31 M−61 V−83 4−04
E−32 N−62 W−91 5−05
F−33 O−63 X−92 6−06
G−41 P−71 Y−93 7−07
H−42 Q−11 Z−12 8−08
I−43 R−72 0−00 9−09
TBL 4−1−5
Helpful Key Entries
# After entering a call sign/tail number, depressing the “pound key” ( #) twice will indicate the end of the
entry.
*2 Will take the user back to the start of the process.
*3 Will repeat the call sign/tail number used in a previous reservation.
*5 Will repeat the previous question.
*8 Tutorial Mode: In the tutorial mode each prompt for input includes a more detailed description of what
is expected as input. *8 is a toggle on/off switch. If you are in tutorial mode and enter *8, you will return
to the normal mode.
*0 Expert Mode: In the expert mode each prompt for input is brief with little or no explanation. Expert
mode is also on/off toggle.
AIM 10/12/17
4−1−20 Services Available to Pilots4−1−22. Requests for Waivers and
Authorizations from Title 14, Code ofFederal Regulations (14 CFR)
a.Requests for a Certificate of Waiver or
Authorization (FAA Form 7711 −2), or requests for
renewal of a waiver or authorization, may be accepted
by any FAA facility and will be forwarded, if
necessary, to the appropriate office having waiver
authority.
b.The grant of a Certificate of Waiver or
Authorization from 14 CFR constitutes relief from
specific regulations, to the degree and for the period
of time specified in the certificate, and does not waiveany state law or local ordinance. Should the proposed
operations conflict with any state law or local
ordinance, or require permission of local authoritiesor property owners, it is the applicant’ s responsibility
to resolve the matter. The holder of a waiver is
responsible for compliance with the terms of thewaiver and its provisions.c.A waiver may be canceled at any time by the
Administrator, the person authorized to grant the
waiver, or the representative designated to monitor a
specific operation. In such case either written notice
of cancellation, or written confirmation of a verbalcancellation will be provided to the holder.
4−1−23. Weather System Processor
The Weather System Processor (WSP) was devel-
oped for use in the National Airspace System to
provide weather processor enhancements to selectedAirport Surveillance Radar (ASR) −9 facilities. The
WSP provides Air Traffic with warnings of
hazardous wind shear and microbursts. The WSP also
provides users with terminal area 6 −level weather,
storm cell locations and movement, as well as the
location and predicted future position and intensity of
wind shifts that may affect airport operations.
AIM 10/12/17
4−2−1 Radio Communications PhraseologySection 2. Radio Communications Phraseology
and Techniques
4−2−1. General
a.Radio communications are a critical link in the
ATC system. The link can be a strong bond between
pilot and controller or it can be broken with surprising
speed and disastrous results. Discussion herein
provides basic procedures for new pilots and also
highlights safe operating concepts for all pilots.
b.The single, most important thought in pilot-
controller communications is understanding. It is
essential, therefore, that pilots acknowledge each
radio communication with ATC by using the
appropriate aircraft call sign. Brevity is important,and contacts should be kept as brief as possible, but
controllers must know what you want to do before
they can properly carry out their control duties. Andyou, the pilot, must know exactly what the controller
wants you to do. Since concise phraseology may not
always be adequate, use whatever words arenecessary to get your message across. Pilots are to
maintain vigilance in monitoring air traffic control
radio communications frequencies for potentialtraffic conflicts with their aircraft especially when
operating on an active runway and/or when
conducting a final approach to landing.
c.All pilots will find the Pilot/Controller Glossary
very helpful in learning what certain words or phrases
mean. Good phraseology enhances safety and is the
mark of a professional pilot. Jargon, chatter, and
“CB” slang have no place in ATC communications.The Pilot/Controller Glossary is the same glossary
used in FAA Order JO 7110.65, Air Traffic Control .
We recommend that it be studied and reviewed fromtime to time to sharpen your communication skills.
4−2−2. Radio Technique
a. Listen before you transmit. Many times you can
get the information you want through ATIS or by
monitoring the frequency. Except for a few situations
where some frequency overlap occurs, if you hear
someone else talking, the keying of your transmitter
will be futile and you will probably jam theirreceivers causing them to repeat their call. If you havejust changed frequencies, pause, listen, and make sure
the frequency is clear.
b. Think before keying your transmitter. Know
what you want to say and if it is lengthy; e.g., a flight
plan or IFR position report, jot it down.
c.The microphone should be very close to your
lips and after pressing the mike button, a slight pause
may be necessary to be sure the first word is
transmitted. Speak in a normal, conversational tone.
d.When you release the button, wait a few
seconds before calling again. The controller or FSS
specialist may be jotting down your number, looking
for your flight plan, transmitting on a differentfrequency, or selecting the transmitter for your
frequency.
e.Be alert to the sounds or the lack of sounds in
your receiver. Check your volume, recheck your
frequency, and make sure that your microphone is not
stuck in the transmit position. Frequency blockage
can, and has, occurred for extended periods of time
due to unintentional transmitter operation. This typeof interference is commonly referred to as a “stuck
mike,” and controllers may refer to it in this manner
when attempting to assign an alternate frequency. Ifthe assigned frequency is completely blocked by this
type of interference, use the procedures described for
en route IFR radio frequency outage to establish orreestablish communications with ATC.
f.Be sure that you are within the performance
range of your radio equipment and the ground station
equipment. Remote radio sites do not always transmit
and receive on all of a facility’s available frequencies,
particularly with regard to VOR sites where you can
hear but not reach a ground station’s receiver.
Remember that higher altitudes increase the range of
VHF “line of sight” communications.
4−2−3. Contact Procedures
a. Initial Contact.
1.The terms initial contact or initial callup
means the first radio call you make to a given facility
or the first call to a different controller or FSSspecialist within a facility. Use the following format:
AIM 10/12/17
4−2−2 Radio Communications Phraseology(a)Name of the facility being called;
(b)Your full aircraft identification as filed in
the flight plan or as discussed in paragraph 4 −2−4,
Aircraft Call Signs;
(c)When operating on an airport surface,
state your position.
(d)The type of message to follow or your
request if it is short; and
(e)The word “Over” if required.
EXAMPLE −
1.“New York Radio, Mooney Three One One Echo.”
2.“Columbia Ground, Cessna Three One Six Zero
Foxtrot, south ramp, I −F−R Memphis.”
3.“Miami Center, Baron Five Six Three Hotel, request
V−F−R traffic advisories.”
2.Many FSSs are equipped with Remote
Communications Outlets (RCOs) and can transmit on
the same frequency at more than one location. The
frequencies available at specific locations areindicated on charts above FSS communications
boxes. To enable the specialist to utilize the correct
transmitter, advise the location and the frequency on
which you expect a reply.
EXAMPLE −
St. Louis FSS can transmit on frequency 122.3 at either
Farmington, Missouri, or Decatur, Illinois, if you are in the
vicinity of Decatur, your callup should be “Saint Louisradio, Piper Six Niner Six Yankee, receiving Decatur OneTwo Two Point Three.”
3.If radio reception is reasonably assured,
inclusion of your request, your position or altitude,
and the phrase “(ATIS) Information Charlie
received” in the initial contact helps decrease radiofrequency congestion. Use discretion; do not
overload the controller with information unneeded or
superfluous. If you do not get a response from theground station, recheck your radios or use another
transmitter, but keep the next contact short.
EXAMPLE −
“Atlanta Center, Duke Four One Romeo, r equest V−F−R
traffic advisories, Twenty Northwest Rome, seven thousand
five hundred, over.”
b. Initial Contact When Your T ransmitting and
Receiving Frequencies are Different.
1.If you are attempting to establish contact with
a ground station and you are receiving on a different
frequency than that transmitted, indicate the VOR
name or the frequency on which you expect a reply.Most FSSs and control facilities can transmit on
several VOR stations in the area. Use the appropriate
FSS call sign as indicated on charts.
EXAMPLE −
New York FSS transmits on the Kennedy, the Hampton, andthe Calverton VORTACs. If you are in the Calverton area,
your callup should be “New Y ork radio, Cessna Three One
Six Zero Foxtrot, r eceiving Calverton V −O−R, over.”
2.If the chart indicates FSS frequencies above
the VORTAC or in the FSS communications boxes,transmit or receive on those frequencies nearest your
location.
3.When unable to establish contact and you
wish to call any ground station, use the phrase “ANY
RADIO (tower) (station), GIVE CESSNA THREEONE SIX ZERO FOXTROT A CALL ON
(frequency) OR (V −O−R).” If an emer gency exists or
you need assistance, so state.
c. Subsequent Contacts and Responses to
Callup from a Ground Facility.
Use the same format as used for the initial contact
except you should state your message or request with
the callup in one transmission. The ground station
name and the word “Over” may be omitted if themessage requires an obvious reply and there is no
possibility for misunderstandings. You should
acknowledge all callups or clearances unless the
controller or FSS specialist advises otherwise. There
are some occasions when controllers must issue
time-critical instructions to other aircraft, and theymay be in a position to observe your response, either
visually or on radar. If the situation demands your
response, take appropriate action or immediatelyadvise the facility of any problem. Acknowledge with
your aircraft identification, either at the beginning or
at the end of your transmission, and one of the words“Wilco,” “Roger,” “Affirmative,” “Negative,” or
other appropriate remarks; e.g., “PIPER TWO ONE
FOUR LIMA, ROGER.” If you have been receivingservices; e.g., VFR traffic advisories and you are
leaving the area or changing frequencies, advise the
ATC facility and terminate contact.
d. Acknowledgement of Frequency Changes.
1.When advised by A TC to change frequencies,
acknowledge the instruction. If you select the new
frequency without an acknowledgement, the control-
ler’s workload is increased because there is no way of
knowing whether you received the instruction or have
had radio communications failure.
AIM 10/12/17
4−2−3 Radio Communications Phraseology2.At times, a controller/specialist may be
working a sector with multiple frequency assign-
ments. In order to eliminate unnecessary verbiage
and to free the controller/specialist for higher priority
transmissions, the controller/specialist may requestthe pilot “(Identification), change to my frequency
123.4.” This phrase should alert the pilot that the
controller/specialist is only changing frequencies, not
controller/specialist, and that initial callup phraseolo-
gy may be abbreviated.
EXAMPLE −
“United Two T wenty−Two on one two three point four” or
“one two three point four, United Two T wenty−Two.”
e. Compliance with Frequency Changes.
When instructed by ATC to change frequencies,
select the new frequency as soon as possible unlessinstructed to make the change at a specific time, fix,
or altitude. A delay in making the change could result
in an untimely receipt of important information. Ifyou are instructed to make the frequency change at a
specific time, fix, or altitude, monitor the frequency
you are on until reaching the specified time, fix, oraltitudes unless instructed otherwise by ATC.
REFERENCE −
AIM, Paragraph 5 −3−1 , ARTCC Communications
4−2−4. Aircraft Call Signs
a. Precautions in the Use of Call Signs.
1.Improper use of call signs can result in pilots
executing a clearance intended for another aircraft.Call signs should never be abbreviated on an initial
contact or at any time when other aircraft call signs
have similar numbers/sounds or identical letters/number; e.g., Cessna 6132F, Cessna 1622F,
Baron 123F, Cherokee 7732F, etc.
EXAMPLE −
Assume that a controller issues an approach clearance to
an aircraft at the bottom of a holding stack and an air craft
with a similar call sign (at the top of the stack)acknowledges the clearance with the last two or threenumbers of the aircraft’ s call sign. If the aircraft at thebottom of the stack did not hear the clearance and
intervene, flight safety would be affected, and there would
be no reason for either the controller or pilot to suspect thatanything is wrong. This kind of “human factors” error can
strike swiftly and is extremely difficult to rectify.
2.Pilots, therefore, must be certain that aircraft
identification is complete and clearly identifiedbefore taking action on an ATC clearance. ATC
specialists will not abbreviate call signs of air carrier
or other civil aircraft having authorized call signs.
ATC specialists may initiate abbreviated call signs of
other aircraft by using the prefix and the last three
digits/letters of the aircraft identification after
communications are established. The pilot may use
the abbreviated call sign in subsequent contacts withthe ATC specialist. When aware of similar/identical
call signs, ATC specialists will take action to
minimize errors by emphasizing certain numbers/let-
ters, by repeating the entire call sign, by repeating the
prefix, or by asking pilots to use a different call sign
temporarily. Pilots should use the phrase “VERIFYCLEARANCE FOR (your complete call sign)” if
doubt exists concerning proper identity.
3.Civil aircraft pilots should state the aircraft
type, model or manufacturer’s name, followed by the
digits/letters of the registration number. When the
aircraft manufacturer’s name or model is stated, the
prefix “N” is dropped; e.g., Aztec Two Four Six Four
Alpha.
EXAMPLE −
1.Bonanza Six Five Five Golf.
2.Breezy Six One Three Romeo Experimental (omit
“Experimental” after initial contact).
4.Air Taxi or other commercial operators not
having FAA authorized call signs should prefix their
normal identification with the phonetic word
“Tango.”
EXAMPLE −
Tango Aztec Two Four Six Four Alpha.
5.Air carriers and commuter air carriers having
FAA authorized call signs should identify themselves
by stating the complete call sign (using group form
for the numbers) and the word “super” or “heavy” ifappropriate.
EXAMPLE −
1.United T wenty−Five Heavy.
2.Midwest Commuter Seven Eleven.
6.Military aircraft use a variety of systems
including serial numbers, word call signs, and
combinations of letters/numbers. Examples includeArmy Copter 48931; Air Force 61782; REACH
31792; Pat 157; Air Evac 17652; Navy Golf Alfa
Kilo 21; Marine 4 Charlie 36, etc.
AIM 10/12/17
4−2−4 Radio Communications Phraseologyb. Air Ambulance Flights.
Because of the priority af forded air ambulance flights
in the ATC system, extreme discretion is necessarywhen using the term “MEDEV AC.” It is only
intended for those missions of an urgent medical
nature and to be utilized only for that portion of theflight requiring expeditious handling. When re-
quested by the pilot, necessary notification to
expedite ground handling of patients, etc., is provided
by ATC; however, when possible, this information
should be passed in advance through non −ATC
communications systems.
1.Civilian air ambulance flights responding to
medical emergencies (first call to an accident scene,
carrying patients, organ donors, organs, or otherurgently needed lifesaving medical material) will be
expedited by ATC when necessary. When expedi-
tious handling is necessary, include the word“MEDEV AC” in the flight plan per paragraphs 5 −1−8
and 5−1−9. In radio communications, use the call
sign“MEDEV AC,” followed by the aircraft registra-tion letters/numbers.
EXAMPLE −
MEDEVAC Two Six Four Six.
2.Similar provisions have been made for the use
of “AIR EV AC” and “HOSP” by air ambulanceflights, except that these flights will receive priority
handling only when specifically requested.
3.Air carrier and air taxi flights responding to
medical emergencies will also be expedited by ATC
when necessary. The nature of these medical
emergency flights usually concerns the transporta-tion of urgently needed lifesaving medical materials
or vital organs. IT IS IMPERATIVE THAT THE
COMPANY/PILOT DETERMINE, BY THENATURE/URGENCY OF THE SPECIFIC
MEDICAL CARGO, IF PRIORITY ATC ASSIST-
ANCE IS REQUIRED. Pilots must include the word
“MEDEV AC” in the flight plan per paragraphs 5 −1−8
and 5−1−9, and use the call sign “MEDEV AC,”
followed by the company name and flight number for
all transmissions when expeditious handling is
required. It is important for ATC to be aware of
“MEDEV AC” status, and it is the pilot’s responsibil-
ity to ensure that this information is provided to ATC.
EXAMPLE −
MEDEVAC Delta Thirty −Seven.c. Student Pilots Radio Identification.
1.The FAA desires to help student pilots in
acquiring sufficient practical experience in the
environment in which they will be required to
operate. To receive additional assistance whileoperating in areas of concentrated air traffic, student
pilots need only identify themselves as a student pilot
during their initial call to an FAA radio facility.
EXAMPLE −
Dayton tower, Fleetwing One Two Three Four, student
pilot.
2.This special identification will alert FAA
ATC personnel and enable them to provide student
pilots with such extra assistance and consideration as
they may need. It is recommended that student pilots
identify themselves as such, on initial contact with
each clearance delivery prior to taxiing, groundcontrol, tower, approach and departure control
frequency, or FSS contact.
4−2−5. Description of Interchange or
Leased Aircraft
a.Controllers issue traffic information based on
familiarity with airline equipment and color/
markings. When an air carrier dispatches a flight
using another company’s equipment and the pilotdoes not advise the terminal AT C facility, the possible
confusion in aircraft identification can compromise
safety.
b.Pilots flying an “interchange” or “leased”
aircraft not bearing the colors/markings of thecompany operating the aircraft should inform the
terminal A TC facility on first contact the name of the
operating company and trip number, followed by the
company name as displayed on the aircraft, and
aircraft type.
EXAMPLE −
Air Cal Three Eleven, United (interchange/lease),
Boeing Seven Two Seven.
4−2−6. Ground Station Call Signs
Pilots, when calling a ground station, should begin
with the name of the facility being called followed by
the type of the facility being called as indicated in
TBL 4−2−1.
AIM 10/12/17
4−2−5 Radio Communications PhraseologyTBL 4−2−1
Calling a Ground Station
Facility Call Sign
Airport UNICOM “Shannon UNICOM”
FAA Flight Service Station “Chicago Radio”
Airport Traffic Control
Tower“Augusta Tower”
Clearance Delivery Position(IFR) “Dallas ClearanceDelivery”
Ground Control Position inTower “Miami Ground”
Radar or NonradarApproach Control Position “Oklahoma CityApproach”
Radar Departure ControlPosition “St. Louis Departure”
FAA Air Route TrafficControl Center “Washington Center”
4−2−7. Phonetic Alphabet
The International Civil Aviation Organization
(ICAO) phonetic alphabet is used by FAA personnel
when communications conditions are such that theinformation cannot be readily received without their
use. ATC facilities may also request pilots to use
phonetic letter equivalents when aircraft with similar
sounding identifications are receiving communica-
tions on the same frequency. Pilots should use the
phonetic alphabet when identifying their aircraftduring initial contact with air traf fic control facilities.
Additionally, use the phonetic equivalents for single
letters and to spell out groups of letters or difficultwords during adverse communications conditions.
(See TBL 4 −2−2.)TBL 4−2−2
Phonetic Alphabet/Morse Code
Character Morse Code TelephonyPhonic
(Pronunciation)
A /C0015 /C0121 Alfa (AL−FAH)
B /C0121 /C0015 /C0015 /C0015 Bravo (BRAH−VOH)
C /C0121 /C0015 /C0121 /C0015 Charlie (CHAR−LEE) or
(SHAR−LEE)
D /C0121 /C0015 /C0015 Delta (DELL−TAH)
E /C0015 Echo (ECK−OH)
F /C0015 /C0015 /C0121 /C0015 Foxtrot (FOKS−TROT)
G /C0121 /C0121 /C0015 Golf (GOLF)
H /C0015 /C0015 /C0015 /C0015 Hotel (HOH−TEL)
I /C0015 /C0015 India (IN−DEE−AH)
J /C0015 /C0121 /C0121 /C0121 Juliett (JEW−LEE−ETT)
K /C0121 /C0015 /C0121 Kilo (KEY−LOH)
L /C0015 /C0121 /C0015 /C0015 Lima (LEE−MAH)
M /C0121 /C0121 Mike (MIKE)
N /C0121 /C0015 November (NO−VEM−BER)
O /C0121 /C0121 /C0121 Oscar (OSS−CAH)
P /C0015 /C0121 /C0121 /C0015 Papa (PAH−PAH)
Q /C0121 /C0121 /C0015 /C0121 Quebec (KEH−BECK)
R /C0015 /C0121 /C0015 Romeo (ROW−ME−OH)
S /C0015 /C0015 /C0015 Sierra (SEE−AIR−RAH)
T /C0121 Tango (TANG−GO)
U /C0015 /C0015 /C0121 Uniform (YOU−NEE−FORM) or
(OO−NEE−FORM)
V /C0015 /C0015 /C0015 /C0121 Victor (VIK−TAH)
W /C0015 /C0121 /C0121 Whiskey (WISS−KEY)
X /C0121 /C0015 /C0015 /C0121 Xray (ECKS−RAY)
Y /C0121 /C0015 /C0121 /C0121 Yankee (YANG−KEY)
Z /C0121 /C0121 /C0015 /C0015 Zulu (ZOO−LOO)
1 /C0015 /C0121 /C0121 /C0121 /C0121 One (WUN)
2 /C0015 /C0015 /C0121 /C0121 /C0121 Two (TOO)
3 /C0015 /C0015 /C0015 /C0121 /C0121 Three (TREE)
4 /C0015 /C0015 /C0015 /C0015 /C0121 Four (FOW−ER)
5 /C0015 /C0015 /C0015 /C0015 /C0015 Five (FIFE)
6 /C0121 /C0015 /C0015 /C0015 /C0015 Six (SIX)
7 /C0121 /C0121 /C0015 /C0015 /C0015 Seven (SEV−EN)
8 /C0121 /C0121 /C0121 /C0015 /C0015 Eight (AIT)
9 /C0121 /C0121 /C0121 /C0121 /C0015 Nine (NIN−ER)
0 /C0121 /C0121 /C0121 /C0121 /C0121 Zero (ZEE−RO)
AIM 10/12/17
4−2−6 Radio Communications Phraseology4−2−8. Figures
a.Figures indicating hundreds and thousands in
round number, as for ceiling heights, and upper wind
levels up to 9,900 must be spoken in accordance with
the following.
EXAMPLE −
1.500 five hundred........
2.4,500 four thousand five hundred ......
b.Numbers above 9,900 must be spoken by
separating the digits preceding the word “thousand.”
EXAMPLE −
1.10,000 one zero thousand .....
2.13,500 one three thousand five hundred .....
c.Transmit airway or jet route numbers as follows.
EXAMPLE −
1.V12 Victor Twelve .......
2.J533 J Five Thirty −Three .......
d.All other numbers must be transmitted by
pronouncing each digit.
EXAMPLE −
10 one zero...........
e.When a radio frequency contains a decimal
point, the decimal point is spoken as “POINT.”
EXAMPLE −
122.1 one two two point one .........
NOTE−
ICAO procedures require the decimal point be spoken as
“DECIMAL.” The F AA will honor such usage by military
aircraft and all other aircraft required to use ICAOprocedures.
4−2−9. Altitudes and Flight Levels
a.Up to but not including 18,000 feet MSL, state
the separate digits of the thousands plus the hundreds
if appropriate.
EXAMPLE −
1.12,000 one two thousand .....
2.12,500 one two thousand five hundred .....
b.At and above 18,000 feet MSL (FL 180), state
the words “flight level” followed by the separate
digits of the flight level.EXAMPLE −
1.190 Flight Level One Niner Zero........
2.275 Flight Level Two Seven Five........
4−2−10. Directions
The three digits of bearing, course, heading, or wind
direction should always be magnetic. The word
“true” must be added when it applies.
EXAMPLE −
1.(Magnetic course) 005 zero zero five ......
2.(True course) 050 zero five zero true ..........
3.(Magnetic bearing) 360 three six zero .....
4.(Magnetic heading) 100 heading one zero .....
zero
5.(Wind direction) 220 wind two two zero ........
4−2−11. Speeds
The separate digits of the speed followed by the word
“KNOTS.” Except, controllers may omit the word
“KNOTS” when using speed adjustment procedures;
e.g., “REDUCE/INCREASE SPEED TO TWO
FIVE ZERO.”
EXAMPLE −
(Speed) 250 two five zero knots .................
(Speed) 190 one niner zero knots .................
The separate digits of the Mach Number preceded by
“Mach.”
EXAMPLE −
(Mach number) 1.5 Mach one point five ............
(Mach number) 0.64 Mach point six four ...........
(Mach number) 0.7 Mach point seven ............
4−2−12. Time
a.FAA uses Coordinated Universal Time (UTC)
for all operations. The word “local” or the time zone
equivalent must be used to denote local when local
time is given during radio and telephone communica-
tions. The term “Zulu” may be used to denote UTC.
EXAMPLE −
0920 UTC zero niner two zero, .....
zero one two zero pacific or local, or one twenty AM
AIM 10/12/17
4−2−7 Radio Communications Phraseologyb.To convert from Standard Time to Coordinated
Universal Time:
TBL 4−2−3
Standard Time to Coordinated Universal Time
Eastern Standard Time .........
Central Standard Time .........
Mountain Standard Time .......
Pacific Standard Time .........
Alaska Standard Time .........
Hawaii Standard Time .........Add 5 hours
Add 6 hours
Add 7 hours
Add 8 hoursAdd 9 hoursAdd 10 hours
NOTE−
For daylight time, subtract 1 hour.
c.A reference may be made to local daylight or
standard time utilizing the 24 −hour clock system. The
hour is indicated by the first two figures and the
minutes by the last two figures.
EXAMPLE −
0000 zero zero zero zero .......................
0920 zero niner two zero .......................
d.Time may be stated in minutes only
(two figures) in radiotelephone communications
when no misunderstanding is likely to occur.
e.Current time in use at a station is stated in the
nearest quarter minute in order that pilots may use this
information for time checks. Fractions of a quarter
minute less than 8 seconds are stated as the preceding
quarter minute; fractions of a quarter minute of
8 seconds or more are stated as the succeeding quarter
minute.
EXAMPLE −
0929:05 time, zero niner two niner ......
0929:10 time, zero niner two niner and ......
one−quarter
4−2−13. Communications with Tower when
Aircraft Transmitter or Receiver or Both are
Inoperative
a. Arriving Aircraft.
1. Receiver inoperative.
(a)If you have reason to believe your receiver
is inoperative, remain outside or above the Class D
surface area until the direction and flow of traffic has
been determined; then, advise the tower of your type
aircraft, position, altitude, intention to land, and
request that you be controlled with light signals.REFERENCE −
AIM, Paragraph 4 −3−13 , Traffic Control Light Signals
(b)When you are approximately 3 to 5 miles
from the airport, advise the tower of your position and
join the airport traffic pattern. From this point on,
watch the tower for light signals. Thereafter, if a
complete pattern is made, transmit your position
downwind and/or turning base leg.
2. Transmitter inoperative. Remain outside
or above the Class D surface area until the direction
and flow of traffic has been determined; then, join the
airport traffic pattern. Monitor the primary local
control frequency as depicted on Sectional Charts for
landing or traffic information, and look for a light
signal which may be addressed to your aircraft.
During hours of daylight, acknowledge towertransmissions or light signals by rocking your wings.
At night, acknowledge by blinking the landing or
navigation lights. To acknowledge tower transmis-sions during daylight hours, hovering helicopters will
turn in the direction of the controlling facility and
flash the landing light. While in flight, helicoptersshould show their acknowledgement of receiving a
transmission by making shallow banks in opposite
directions. At night, helicopters will acknowledgereceipt of transmissions by flashing either the landing
or the search light.
3. Transmitter and receiver inoperative.
Remain outside or above the Class D surface area
until the direction and flow of traffic has beendetermined; then, join the airport traffic pattern and
maintain visual contact with the tower to receive light
signals. Acknowledge light signals as noted above.
b. Departing Aircraft. If you experience radio
failure prior to leaving the parking area, make everyeffort to have the equipment repaired. If you are
unable to have the malfunction repaired, call the
tower by telephone and request authorization to
depart without two-way radio communications. If
tower authorization is granted, you will be givendeparture information and requested to monitor the
tower frequency or watch for light signals as
appropriate. During daylight hours, acknowledgetower transmissions or light signals by moving the
ailerons or rudder. At night, acknowledge by blinking
the landing or navigation lights. If radio malfunction
AIM 10/12/17
4−2−8 Radio Communications Phraseologyoccurs after departing the parking area, watch the
tower for light signals or monitor tower frequency.
REFERENCE −
14 CFR Section 91.125 and 14 CFR Section 91.129.
4−2−14. Communications for VFR Flights
a.FSSs and Supplemental Weather Service
Locations (SWSL) are allocated frequencies for
different functions; for example, in Alaska, certainFSSs provide Local Airport Advisory on 123.6 MHz
or other frequencies which can be found in the Chart
Supplement U.S. If you are in doubt as to whatfrequency to use, 122.2 MHz is assigned to the
majority of FSSs as a common en route simplex
frequency.NOTE−
In order to expedite communications, state the frequencybeing used and the aircraft location during initial callup.
EXAMPLE −
Dayton radio, November One Two Three Four Five on one
two two point two, over Springfield V −O−R, over.
b.Certain VOR voice channels are being utilized
for recorded broadcasts; i.e., ATIS, HIWAS, etc.These services and appropriate frequencies are listed
in the Chart Supplement U.S. On VFR flights, pilots
are urged to monitor these frequencies. When incontact with a control facility, notify the controller if
you plan to leave the frequency to monitor these
broadcasts.
AIM 10/12/17
4−3−1 Airport OperationsSection 3. Airport Operations
4−3−1. General
Increased traffic congestion, aircraft in climb and
descent attitudes, and pilot preoccupation with
cockpit duties are some factors that increase the
hazardous accident potentia l near the airport. The
situation is further compounded when the weather is
marginal, that is, just meeting VFR requirements.
Pilots must be particularly alert whe n operating in the
vicinity of an airport. This section defines some rules,
practices, and procedures that pilots should be
familiar with and adhere to for safe airport operations.
4−3−2. Airports with an Operating Control
Tower
a.When operating at an airport where traffic
control is being exercised by a control tower, pilots
are required to maintain two −way radio contact with
the tower while operating within the Class B, Class C,
and Class D surface area unless the tower authorizes
otherwise. Initial callup should be made about15 miles from the airport. Unless there is a good
reason to leave the tower frequency before exiting the
Class B, Class C, and Class D surface areas, it is agood operating practice to remain on the tower
frequency for the purpose of receiving traffic
information. In the interest of reducing towerfrequency congestion, pilots are reminded that it is
not necessary to request permission to leave the tower
frequency once outside of Class B, Class C, andClass D surface areas. Not all airports with an
operating control tower will have Class D airspace.
These airports do not have weather reporting whichis a requirement for surface based controlled
airspace, previously known as a control zone. The
controlled airspace over these airports will normally
begin at 700 feet or 1,200 feet above ground level and
can be determined from the visual aeronauticalcharts. Pilots are expected to use good operating
practices and communicate with the control tower as
described in this section.
b.When necessary, the tower controller will issue
clearances or other information for aircraft to
generally follow the desired flight path (traffic
patterns) when flying in Class B, Class C, and Class D
surface areas and the proper taxi routes whenoperating on the ground. If not otherwise authorizedor directed by the tower, pilots of fixed −wing aircraft
approaching to land must circle the airport to the left.
Pilots approaching to land in a helicopter must avoid
the flow of fixed −wing traffic. However, in all
instances, an appropriate clearance must be received
from the tower before landing.
FIG 4−3−1
Components of a Traffic Pattern
NOTE−
This diagram is intended only to illustrate terminology
used in identifying various components of a traffic pattern.
It should not be used as a r eference or guide on how to enter
a traffic pattern.
c.The following terminology for the various
components of a traffic pattern has been adopted as
standard for use by control towers and pilots (SeeFIG 4−3−1):
1. Upwind leg. A flight path parallel to the
landing runway in the direction of landing.
2. Crosswind leg. A flight path at right angles
to the landing runway off its takeoff end.
3. Downwind leg. A flight path parallel to the
landing runway in the opposite direction of landing.
4. Base leg. A flight path at right angles to the
landing runway off its approach end and extendingfrom the downwind leg to the intersection of the
extended runway centerline.
5. Final approach. A flight path in the
direction of landing along the extended runway
centerline from the base leg to the runway.
6. Departure leg. The flight path which begins
after takeoff and continues straight ahead along the
extended runway centerline. The departure climbcontinues until reaching a point at least
1/2 mile
AIM 10/12/17
4−3−2 Airport Operationsbeyond the departure end of the runway and within
300 feet of the traffic pattern altitude.
d.Many towers are equipped with a tower radar
display. The radar uses are intended to enhance theeffectiveness and efficiency of the local control, or
tower, position. They are not intended to provide
radar services or benefits to pilots except as they may
accrue through a more efficient t ower operation. The
four basic uses are:
1. To determine an aircraft’s exact location.
This is accomplished by radar identifying the VFR
aircraft through any of the techniques available to aradar position, such as having the aircraft squawk
ident . Once identified, the aircraft’s position and
spatial relationship to other aircraft can be quicklydetermined, and standard instructions regarding VFR
operation in Class B, Class C, and Class D surface
areas will be issued. Once initial radar identification
of a VFR aircraft has been established and the
appropriate instructions have been issued, radarmonitoring may be discontinued; the reason being
that the local controller’s primary means of
surveillance in VFR conditions is visually scanningthe airport and local area.
2. To provide radar traffic advisories. Radar
traffic advisories may be provided to the extent that
the local controller is able to monitor the radar
display. Local control has primary control responsibi-
lities to the aircraft operating on the runways, which
will normally supersede radar monitoring duties.
3. To provide a direction or suggested
heading. The local controller may provide pilots
flying VFR with generalized instructions which will
facilitate operations; e.g., “PROCEED SOUTH-
WESTBOUND, ENTER A RIGHT DOWNWINDRUNWAY THREE ZERO,” or provide a suggested
heading to establish radar identification or as an
advisory aid to navigation; e.g., “SUGGESTEDHEADING TWO TWO ZERO, FOR RADAR
IDENTIFICATION.” In both cases, the instructions
are advisory aids to the pilot flying VFR and are notradar vectors.
NOTE−
Pilots have complete discretion regarding acceptance ofthe suggested headings or directions and have sole
responsibility for seeing and avoiding other aircraft.
4. To provide information and instructions to
aircraft operating within Class B, Class C, andClass D surface areas. In an example of this
situation, the local controller would use the radar to
advise a pilot on an extended downwind when to turn
base leg.
NOTE−
The above tower radar applications are intended toaugment the standard functions of the local controlposition. There is no controller requirement to maintainconstant radar identification. In fact, such a requirement
could compromise the local controller’ s ability to visually
scan the airport and local area to meet F AA r esponsibilities
to the aircraft operating on the runways and within theClass B, Class C, and Class D surface areas. Normally,pilots will not be advised of being in radar contact since
that continued status cannot be guaranteed and since the
purpose of the radar identification is not to establish a link
for the provision of radar services.
e.A few of the radar equipped towers are
authorized to use the radar to ensure separation
between aircraft in specific situations, while stillothers may function as limited radar approach
controls. The various radar uses are strictly a function
of FAA operational need. The facilities may beindistinguishable to pilots since they are all referred
to as tower and no publication lists the degree of radar
use. Therefore, when in communication with a
tower controller who may have radar available, do
not assume that constant radar monitoring and
complete ATC radar services are being provided
4−3−3. Traffic Patterns
a.At most airports and military air bases, traffic
pattern altitudes for propeller −driven aircraft gener-
ally extend from 600 feet to as high as 1,500 feet
above the ground. Also, traffic pattern altitudes formilitary turbojet aircraft sometimes extend up to
2,500 feet above the ground. Therefore, pilots of en
route aircraft should be constantly on the alert forother aircraft in traffic patterns and avoid these areas
whenever possible. Traffic pattern altitudes should be
maintained unless otherwise required by theapplicable distance from cloud criteria (14 CFR
Section 91.155). (See FIG 4−3−2 and FIG 4−3−3.)
Unless otherwise indicated, all turns in the trafficpattern should be made to the left. On Sectional
Aeronautical and VFR Terminal Area Charts, right
traffic patterns are indicated at public-use andjoint-use airports by the abbreviation “RP” (for Right
Pattern), followed by the appropriate runway
number(s), at the bottom of the airport data block.
AIM 10/12/17
4−3−3 Airport OperationsEXAMPLE −
RP 9, 18, 22R
NOTE−
1.RP* indicates special conditions exist and refers pilots
to the Chart Supplement U.S.
2.Right traffic patterns are not shown at airports with
full−time control towers.b.Wind conditions affect all airplanes in varying
degrees. Figure 4-3-4 is an example of a chart used to
determine the headwind, crosswind, and tailwind
components based on wind direction and velocity
relative to the runway. Pilots should refer to similarinformation provided by the aircraft manufacturer
when determining these wind components.
FIG 4−3−2
Traffic Pattern Operations
Single Runway
EXAMPLE −
Key to traffic pattern operations
1.Enter pattern in level flight, abeam the midpoint of the
runway, at pattern altitude. (1,000’ AGL is recommended
pattern altitude unless established otherwise. . .)
2.Maintain pattern altitude until abeam approach end of
the landing runway on downwind leg.
3.Complete turn to final at least 1/4 mile from the runway.4.Continue straight ahead until beyond departure end of
runway.
5.If remaining in the traffic pattern, commence turn to
crosswind leg beyond the de parture end of the runway
within 300 feet of pattern altitude.
6.If departing the traffic pattern, continue straight out, or
exit with a 45 degree turn (to the left when in a left−hand
traffic pattern; to the right when in a right −hand traffic
pattern) beyond the departure end of the runway, afterreaching pattern altitude.
AIM 10/12/17
4−3−4 Airport OperationsFIG 4−3−3
Traffic Pattern Operations
Parallel Runways
EXAMPLE −
Key to traffic pattern operations
1.Enter pattern in level flight, abeam the midpoint of the
runway, at pattern altitude. (1,000’ AGL is recommended
pattern altitude unless established otherwise. . .)
2.Maintain pattern altitude until abeam approach end of
the landing runway on downwind leg.
3.Complete turn to final at least 1/4 mile from the runway.
4.Continue straight ahead until beyond departure end of
runway.5.If remaining in the traffic pattern, commence turn to
crosswind leg beyond the de parture end of the runway
within 300 feet of pattern altitude.
6.If departing the traffic pattern, continue straight out, or
exit with a 45 degree turn (to the left when in a left−hand
traffic pattern; to the right when in a right −hand traffic
pattern) beyond the departure end of the runway, afterreaching pattern altitude.
7.Do not overshoot final or continue on a track which will
penetrate the final approach of the parallel runway.
8.Do not continue on a track which will penetrate the
departure path of the parallel runway.
AIM 10/12/17
4−3−5 Airport OperationsFIG 4−3−4
Headwind/Tailwind/Crosswind Component Calculator
AIM 10/12/17
4−3−6 Airport Operations4−3−4. Visual Indicators at Airports
Without an Operating Control Tower
a.At those airports without an operating control
tower, a segmented circle visual indicator system, if
installed, is designed to provide traffic pattern
information.
REFERENCE −
AIM, Paragraph 4 −1−9 , Traffic Advisory Practices at Airports Without
Operating Control Towers
b.The segmented circle system consists of the
following components:
1. The segmented cir cle. Located in a position
affording maximum visibility to pilots in the air and
on the ground and providing a centralized location for
other elements of the system.
2. The wind dir ection indicator. A wind cone,
wind sock, or wind tee installed near the operational
runway to indicate wind direction. The large end of
the wind cone/wind sock points into the wind as does
the large end (cross bar) of the wind tee. In lieu of a
tetrahedron and where a wind sock or wind cone is
collocated with a wind tee, the wind tee may bemanually aligned with the runway in use to indicate
landing direction. These signaling devices may be
located in the center of the segmented circle and may
be lighted for night use. Pilots are cautioned against
using a tetrahedron to indicate wind direction.
3. The landing direction indicator. A tetrahe-
dron is installed when conditions at the airport
warrant its use. It may be used to indicate the direction
of landings and takeoffs. A tetrahedron may be
located at the center of a segmented circle and may be
lighted for night operations. The small end of thetetrahedron points in the direction of landing. Pilots
are cautioned against using a tetrahedron for any
purpose other than as an indicator of landingdirection. Further, pilots should use extreme caution
when making runway selection by use of a
tetrahedron in very light or calm wind conditions asthe tetrahedron may not be aligned with the
designated calm −wind runway. At airports with
control towers, the tetrahedron should only bereferenced when the control tower is not in operation.
Tower instructions supersede tetrahedron indica-
tions.
4. Landing strip indicators. Installed in pairs
as shown in the segmented circle diagram and used to
show the alignment of landing strips.5. Traffic pattern indicators. Arranged in
pairs in conjunction with landing strip indicators and
used to indicate the direction of turns when there is a
variation from the normal left traf fic pattern. (If there
is no segmented circle installed at the airport, trafficpattern indicators may be installed on or near the end
of the runway.)
c.Preparatory to landing at an airport without a
control tower, or when the control tower is not in
operation, pilots should concern themselves with the
indicator for the approach end of the runway to be
used. When approaching for landing, all turns must
be made to the left unless a traffic pattern indicatorindicates that turns should be made to the right. If the
pilot will mentally enlarge the indicator for the
runway to be used, the base and final approach legsof the traffic pattern to be flown immediately become
apparent. Similar treatment of the indicator at the
departure end of the runway will clearly indicate thedirection of turn after takeoff.
d.When two or more aircraft are approaching an
airport for the purpose of landing, the pilot of the
aircraft at the lower altitude has the right −of−way
over the pilot of the aircraft at the higher altitude.However, the pilot operating at the lower altitude
should not take advantage of another aircraft, which
is on final approach to land, by cutting in front of, orovertaking that aircraft.
4−3−5. Unexpected Maneuvers in the
Airport Traffic Pattern
There have been several incidents in the vicinity of
controlled airports that were caused primarily by
aircraft executing unexpected maneuvers. ATC
service is based upon observed or known traffic andairport conditions. Controllers establish the sequence
of arriving and departing aircraft by requiring them to
adjust flight as necessary to achieve proper spacing.These adjustments can only be based on observed
traffic, accurate pilot reports, and anticipated aircraft
maneuvers. Pilots are expected to cooperate so as topreclude disrupting traffic flows or creating
conflicting patterns. The pilot −in−command of an
aircraft is directly responsible for and is the finalauthority as to the operation of the aircraft. On
occasion it may be necessary for pilots to maneuver
their aircraft to maintain spacing with the traffic they
have been sequenced to follow. The controller can
anticipate minor maneuvering such as shallow “S”
turns. The controller cannot, however, anticipate a
AIM 10/12/17
4−3−7 Airport Operationsmajor maneuver such as a 360 degree turn. If a pilot
makes a 360 degree turn after obtaining a landing
sequence, the result is usually a gap in the landing
interval and, more importantly, it causes a chain
reaction which may result in a conflict with following
traffic and an interruption of the sequence established
by the tower or approach controller. Should a pilot
decide to make maneuvering turns to maintainspacing behind a preceding aircraft, the pilot should
always advise the controller if at all possible. Except
when requested by the controller or in emergencysituations, a 360 degree turn should never be executed
in the traffic pattern or when receiving radar service
without first advising the controller.
4−3−6. Use of Runways/Declared Distances
a.Runways are identified by numbers which
indicate the nearest 10-degree increment of the
azimuth of the runway centerline. For example,
where the magnetic azimuth is 183 degrees, therunway designation would be 18; for a magnetic
azimuth of 87 degrees, the runway designation would
be 9. For a magnetic azimuth ending in the number 5,such as 185, the runway designation could be either
18 or 19. Wind direction issued by the tower is also
magnetic and wind velocity is in knots.
b.Airport proprietors are responsible for taking
the lead in local aviation noise control. Accordingly,
they may propose specific noise abatement plans to
the FAA. If approved, these plans are applied in the
form of Formal or Informal Runway Use Programs
for noise abatement purposes.
REFERENCE −
Pilot/Controller Glossary Term − Runway Use Program
1.At airports where no runway use program is
established, ATC clearances may specify:
(a)The runway most nearly aligned with the
wind when it is 5 knots or more;
(b)The “calm wind” runway when wind is
less than 5 knots; or
(c)Another runway if operationally advanta-
geous.
NOTE−
It is not necessary for a controller to specifically inquire if
the pilot will use a specific runway or to offer a choice of
runways. If a pilot prefers to use a different runway from
that specified, or the one most nearly aligned with the wind,
the pilot is expected to inform ATC accordingly.2.At airports where a runway use program is
established, A TC will assign runways deemed to have
the least noise impact. If in the interest of safety a
runway different from that specified is preferred, the
pilot is expected to advise ATC accordingly. A TC will
honor such requests and advise pilots when the
requested runway is noise sensitive. When use of a
runway other than the one assigned is requested, pilot
cooperation is encouraged to preclude disruption of
traffic flows or the creation of conflicting patterns.
c. Declared Distances.
1.Declared distances for a runway represent
the maximum distances available and suitable formeeting takeoff and landing distance performance
requirements. These distances are determined in
accordance with FAA runway design standards byadding to the physical length of paved runway any
clearway or stopway and subtracting from that sum
any lengths necessary to obtain the standard runwaysafety areas, runway obj ect free areas, or runway
protection zones. As a result of these additions and
subtractions, the declared distances for a runway may
be more or less than the physical length of the runway
as depicted on aeronautical charts and related
publications, or available in electronic navigation
databases provided by either the U.S. Government or
commercial companies.
2.All 14 CFR Part 139 airports report declared
distances for each runway. Other airports may also
report declared distances for a runway if necessaryto meet runway design standards or to indicate the
presence of a clearway or stopway. Where reported,
declared distances for each runway end arepublished in the Chart Supplement U.S. For runways
without published declared distances, the declared
distances may be assumed to be equal to the physical
length of the runway unless there is a displaced
landing threshold, in which case the LandingDistance A vailable (LDA) is shortened by the amount
of the threshold displacement.
NOTE−
A symbol
is shown on U.S. Government charts to
indicate that runway declared distance information isavailable (See appropriate Chart Supplement U.S., ChartSupplement Alaska or Pacific).
(a)The FAA uses the following definitions
for runway declared distances (See FIG 4−3−5):
REFERENCE −
Pilot/Controller Glossary Terms: “Accelerate −Stop Distance
Available,” “Landing Distance Av ailable,” “Takeoff Distance
Available,” “Takeoff Run Available,” ” Stopway,” and “Clearway.”
AIM 10/12/17
4−3−8 Airport Operations(1)Takeoff Run Available (TORA) – The
runway length declared av ailable and suitable for
the ground run of an airplane taking off.
The TORA is typically the physical length of the
runway, but it may be shorter than the runway length
if necessary to satisfy runway design standards. For
example, the TORA may be shorter than the runwaylength if a portion of the runway must be used to
satisfy runway protection zone requirements.
(2)Takeoff Distance Available (TODA) –
The takeoff run available plus the length of any
remaining runway or clearway beyond the far end of
the takeoff run available.
The TODA is the distance declared available for
satisfying takeoff distance requirements for airplanes
where the certification and operating rules andavailable performance data allow for the considera-
tion of a clearway in takeoff performance
computations.
NOTE−
The length of any available clearway will be included in theTODA published in the entry for that runway end within the
Chart Supplement U.S.
(3)Accelerate −Stop Distance Available
(ASDA) – The runway plus stopway length declared
available and suitable for the acceleration and
deceleration of an airplane aborting a takeoff.
The ASDA may be longer than the physical length of
the runway when a stopway has been designatedavailable by the airport operator, or it may be shorter
than the physical length of the runway if necessary to
use a portion of the runway to satisfy runway designstandards; for example, where the airport operator
uses a portion of the runway to achieve the runway
safety area requirement. ASDA is the distance usedto satisfy the airplane accelerate −stop distance
performance requirements where the certification
and operating rules require accelerate −stop distance
computations.
NOTE−
The length of any available stopway will be included in theASDA published in the entry for that runway end within the
Chart Supplement U.S.
(4)Landing Distance Available (LDA) −
The runway length declared available and suitable
for a landing airplane.
The LDA may be less than the physical length of the
runway or the length of the runway remaining beyonda displaced threshold if necessary to satisfy runway
design standards;for example, where the airport
operator uses a portion of the runway to achieve the
runway safety area requirement.
Although some runway elements (such as stopway
length and clearway length) may be available
information, pilots must use the declared distancesdetermined by the airport operator and not attempt to
independently calculate declared distances by
adding those elements to the reported physicallength of the runway.
(b)The airplane operating rules and/or the
airplane operating limitations establish minimum
distance requirements for takeoff and landing and
are based on performance data supplied in the
Airplane Flight Manual or Pilot’s Operating
Handbook. The minimum distances required fortakeoff and landing obtained either in planning
prior to takeoff or in performance assessments
conducted at the time of landing must fall within
the
applicable declared distances before the pilot can
accept that runway for takeoff or landing.
(c)Runway design standards may impose
restrictions on the amount of runway available for
use in takeoff and landing that are not apparentfrom the reported physical length of the runway or
from runway markings and lighting. The runway
elements of Runway Safety Area (RSA), RunwayObject Free Area (ROFA), and Runway Protection
Zone (RPZ) may reduce a runway’s declared
distances to less than the physical length of the
runway at geographically constrained airports (See
FIG 4−3−6). When considering the amount of
runway available for use in takeoff or landing
performance calculations, the declared distances
published for a runway must always be used in lieuof the runway’s physical length.
REFERENCE −
AC 150/5300 −13, Airport Design
(d)While some runway elements associated
with declared distances may be identifiable through
runway markings or lighting (for example, a
displaced threshold or a stopway), the individualdeclared distance limits are not marked or otherwise
identified on the runway. An aircraft is not
prohibited from operating beyond a declared
distance limit during the takeoff, landing, or taxi
operation provided the runway surface is appropri-
ately marked as usable runway (See FIG 4 −3−6). The
AIM 10/12/17
4−3−9 Airport Operationsfollowing examples clarify the intent of this
paragraph.
REFERENCE −
AIM, Paragraph 2 −3−3 , Runway Markings
AC 150/5340 −1, Standards for Airport Markings
EXAMPLE −
1.The declared LDA for runway 9 must be used when
showing compliance with the landing distance require-ments of the applicable airplane operating rules and/or
airplane operating limitations or when making a before
landing performance assessment. The LDA is less than the
physical runway length, not only because of the displaced
threshold, but also because of the subtractions necessaryto meet the RSA beyond the far end of the runway. However,
during the actual landing operation, it is permissible forthe airplane to roll beyond the unmarked end of the LDA.
2.The declared ASDA for runway 9 must be used when
showing compliance with the accelerate −stop distance
requirements of the applicable airplane operating rules
and/or airplane operating limitations. The ASDA is lessthan the physical length of the runway due to subtractions
necessary to ac hieve the full RSA r equir ement. However, in
the event of an aborted takeoff, it is permissible for theairplane to roll beyond the unmarked end of the ASDA asit is brought to a full −stop on the r emaining usable runway.
AIM 10/12/17
4−3−10 Airport OperationsFIG 4−3−5
Declared Distances with Full −Standard Runway Safety Areas, Runway Object Free Areas, and Runway
Protection Zones
AIM 10/12/17
4−3−11 Airport OperationsFIG 4−3−6
Effects of a Geographical Constraint on a Runway’s Declared Distances
NOTE−
A runway’ s RSA begins a set distance prior to the threshold and will extend a set distance beyond the end of the runwaydepending on the runway’ s design criteria. If these required lengths cannot be achieved, the ASDA and/or LDA will bereduced as necessary to obtain the required lengths to the extent practicable.
AIM 10/12/17
4−3−12 Airport Operations4−3−7. Low Level Wind Shear/Microburst
Detection Systems
Low Level Wind Shear Alert System (LLWAS),
Terminal Doppler Weather Radar (TDWR), Weather
System Processor (WSP), and Integrated TerminalWeather System (ITWS) display information on
hazardous wind shear and microburst activity in the
vicinity of an airport to air traffic controllers whorelay this information to pilots.
a.LLWAS provides wind shear alert and gust front
information but does not provide microburst alerts.
The LLWAS is designed to detect low level wind
shear conditions around the periphery of an airport. It
does not detect wind shear beyond that limitation.Controllers will provide this information to pilots by
giving the pilot the airport wind followed by the
boundary wind.
EXAMPLE −
Wind shear alert, airport wind 230 at 8, south boundary
wind 170 at 20.
b.LLWAS “network expansion,” (LLWAS NE)
and LLWAS Relocation/Sustainment (LLWAS −RS)
are systems integrated with TDWR. These systems
provide the capability of detecting microburst alertsand wind shear alerts. Controllers will issue the
appropriate wind shear alerts or microburst alerts. In
some of these systems controllers also have the ability
to issue wind information oriented to the threshold or
departure end of the runway.
EXAMPLE −
Runway 17 arrival microburst alert, 40 knot loss 3 milefinal.
REFERENCE −
AIM, Paragraph 7 −1−26 , Microbursts
c.More advanced systems are in the field or being
developed such as ITWS. ITWS provides alerts for
microbursts, wind shear, and significant thunder-
storm activity. ITWS displays wind informationoriented to the threshold or departure end of the
runway.
d.The WSP provides weather processor enhance-
ments to selected Airport Surveillance Radar(ASR)−9 facilities. The WSP provides Air Traffic
with detection and alerting of hazardous weather such
as wind shear, microbursts, and significant thunder-storm activity. The WSP displays terminal area
6 level weather, storm cell locations and movement,
as well as the location and predicted future positionand intensity of wind shifts that may affect airport
operations. Controllers will receive and issue alerts
based on Areas Noted for Attention (ARENA). An
ARENA extends on the runway center line from a
3 mile final to the runway to a 2 mile departure.
e.An airport equipped with the LLWAS, ITWS, or
WSP is so indicated in the Chart Supplement U.S.
under Weather Data Sources for that particularairport.
4−3−8. Braking Action Reports and
Advisories
a.When available, ATC furnishes pilots the
quality of braking action received from pilots. The
quality of braking action is described by the terms
“good,” “good to medium,” “medium,” “medium topoor,” “poor,” and “nil.” When pilots report the
quality of braking action by using the terms noted
above, they should use descriptive terms that areeasily understood, such as, “braking action poor the
first/last half of the runway,” together with the
particular type of aircraft.
b.FICON NOTAMs will provide contaminant
measurements for paved runways; however, aFICON NOTAM for braking action will only be used
for non−paved runway surfaces, taxiways, and
aprons. These NOTAMs are classified according tothe most critical term (“good to medium,” “medium,”
“medium to poor,” and “poor”).
1.FICON NOTAM reporting of a braking
condition for paved runway surfaces is not
permissible by Federally Obligated Airports or those
airports certificated under 14 CFR Part 139.
2.A “NIL” braking condition at these airports
must be mitigated by closure of the affected surface.
Do not include the type of vehicle in the FICON
NOTAM.
c.When tower controllers receive runway braking
action reports which include the terms medium, poor,
or nil, or whenever weather conditions are conducive
to deteriorating or rapidly changing runway braking
conditions, the tower will include on the ATISbroadcast the statement, “BRAKING ACTION
ADVISORIES ARE IN EFFECT.”
d.During the time that braking action advisories
are in effect, ATC will issue the most recent braking
action report for the runway in use to each arriving
and departing aircraft. Pilots should be prepared for
AIM 10/12/17
4−3−13 Airport Operationsdeteriorating braking conditions and should request
current runway condition information if not issued by
controllers. Pilots should also be prepared to provide
a descriptive runway condition report to controllers
after landing.
4−3−9. Runway Condition Reports
a.Aircraft braking coefficient is dependent upon
the surface friction between the tires on the aircraftwheels and the pavement surface. Less friction means
less aircraft braking coefficient and less aircraft
braking response.
b.Runway condition code (RwyCC) values range
from 1 (poor) to 6 (dry). For frozen contaminants on
runway surfaces, a runway condition code reading of
4 indicates the level when braking deceleration or
directional control is between good and medium.
NOTE−
A RwyCC of “0” is used to delineate a braking action
report of NIL and is prohibited from being reported in a
FICON NOTAM.
c.Airport management should conduct runway
condition assessments on wet runways or runways
covered with compacted snow and/or ice.
1.Numerical readings may be obtained by using
the Runway Condition Assessment Matrix (RCAM).
The RCAM provides the airport operator with data to
complete the report that includes the following:
(a)Runway(s) in use
(b)Time of the assessment
(c)Runway condition codes for each zone
(touchdown, mid −point, roll −out)(d)Pilot−reported braking action report (if
available)
(e)The contaminant (for example, wet snow,
dry snow, slush, ice, etc.)
2.Assessments for each zone (see 4 −3−9c1(c))
will be issued in the direction of takeoff and landing
on the runway, ranging from “1” to “6” to describe
contaminated surfaces.
NOTE−
A RwyCC of “0” is used to delineate a braking action
report of NIL and is prohibited from being reported in aFICON NOTAM.
3.When any 1 or more runway condition codes
are reported as less than 6, airport management mustnotify ATC for dissemination to pilots.
4.Controllers will not issue runway condition
codes when all 3 segments of a runway are reporting
values of 6.
d.When runway condition code reports are
provided by airport management, the ATC facility
providing approach control or local airport advisory
must provide the report to all pilots.
e.Pilots should use runway condition code
information with other knowledge including aircraft
performance characteristics, type, and weight,
previous experience, wind conditions, and aircrafttire type (such as bias ply vs. radial constructed) to
determine runway suitability.
f.The Runway Condition Assessment Matrix
identifies the descriptive terms “good,” “good tomedium,” “medium,” “medium to poor,” “poor,” and
“nil” used in braking action reports.
REFERENCE −
Advisory Circular AC 91 −79A (Revision 1), Mitigating the Risks of a
Runway Overrun Upon Landing, Appendix 1
AIM 10/12/17
4−3−14 Airport OperationsFIG 4−3−7
Runway Condition Assessment Matrix (RCAM)
AIM 10/12/17
4−3−15 Airport Operations4−3−10. Intersection Takeoffs
a.In order to enhance airport capacities, reduce
taxiing distances, minimize departure delays, and
provide for more efficient movement of air traffic,
controllers may initiate intersection takeoffs as well
as approve them when the pilot requests. If for ANY
reason a pilot prefers to use a different intersection or
the full length of the runway or desires to obtain the
distance between the intersection and the runway end,
THE PILOT IS EXPECTED TO INFORM ATC
ACCORDINGLY .
b.Pilots are expected to assess the suitability of an
intersection for use at takeoff during their preflight
planning. They must consider the resultant length
reduction to the published runway length and to thepublished declared distances from the intersection
intended to be used for takeof f. The minimum runway
required for takeoff must fall within the reduced
runway length and the reduced declared distances
before the intersection can be accepted for takeoff.
REFERENCE−
AIM, Paragraph 4 −3−6 , Use of Runways/Declared Distances
c.Controllers will issue the measured distance
from the intersection to the runway end rounded
“down” to the nearest 50 feet to any pilot whorequests and to all military aircraft, unless use of the
intersection is covered in appropriate directives.
Controllers, however, will not be able to inform pilots
of the distance from the intersection to the end of any
of the published declared distances.
REFERENCE−
F AA Order JO 71 10.65, Paragraph 3 −7−1, Ground Traffic Movement
d.An aircraft is expected to taxi to (but not onto)
the end of the assigned runway unless prior approval
for an intersection departure is received from ground
control.
e.Pilots should state their position on the airport
when calling the tower for takeoff from a runway
intersection.
EXAMPLE−
Cleveland Tower, Apache Three Seven Two Two Papa, atthe intersection of taxiway Oscar and runway two three
right, ready for departure.
f.Controllers are required to separate small
aircraft that are departing from an intersection on the
same runway (same or opposite direction) behind a
large nonheavy aircraft (except B757), by ensuring
that at least a 3 −minute interval exists between thetime the preceding large aircraft has taken off and the
succeeding small aircraft begins takeoff roll. The3−minute separation requirement will a lso be applied
to small aircraft with a maximum certificated takeoffweight of 12,500 pounds or less departing behind asmall aircraft with a maximum certificated takeoff
weight of more than 12,500 pounds. To inform the
pilot of the required 3 −minute hold, the controller will
state, “Hold for wake turbulence.” If after consider-
ing wake turbulence hazards, the pilot feels that a
lesser time interval is appropriate, the pilot mayrequest a waiver to the 3 −minute interval. To initiate
such a request, simply say “Request waiver to3−minute interval” or a similar statement. Controllers
may then issue a takeoff clearance if other traffic
permits, since the pilot has accepted the responsibility
for wake turbulence separation.
g.The 3− minute interval is not required when the
intersection is 500 feet or less from the departure
point of the preceding aircraft and both aircraft are
taking off in the same direction. Controllers may
permit the small aircraft to alter course after takeoffto avoid the flight path of the preceding departure.
h.A 4−minute interval is mandatory for small,
large, and heavy aircraft behind a super aircraft. The3−minute interval is mandatory behind a heavy
aircraft in all cases, and for small aircraft behind aB757.
4−3−11. Pilot Responsibilities When
Conducting Land and Hold Short
Operations (LAHSO)
a.LAHSO is an acronym for “Land and Hold
Short Operations.” These operations include landingand holding short of an intersecting runway, anintersecting taxiway, or some other designated point
on a runway other than an intersecting runway or
taxiway. (See FIG 4− 3−8, FIG 4− 3−9, FIG 4−3−10.)
b. Pilot Responsibilities and Basic Procedures.
1.LAHSO is an air traf fic control procedure that
requires pilot participation to balance the needs for
increased airport capacity and system efficiency,
consistent with safety. This procedure can be donesafely provided pilots and controllers are knowledge-
able and understand their responsibilities. Thefollowing paragraphs outline specific pilot/operatorresponsibilities when conducting LAHSO.
2.At controlled airports, air traffic may clear a
pilot to land and hold short. Pilots may accept such a
AIM 10/12/17
4−3−16 Airport Operationsclearance provided that the pilot −in−command
determines that the aircraft can safely land and stop
within the Available Landing Distance (ALD). ALD
data are published in the special notices section of the
Chart Supplement U.S. and in the U.S. Terminal
Procedures Publications. Controllers will also
provide ALD data upon request. Student pilots or
pilots not familiar with LAHSO should notparticipate in the program.
3.The pilot−in−command has the final authori-
ty to accept or decline any land and hold shortclearance. The safety and operation of the aircraftremain the responsibility of the pilot. Pilots are
expected to decline a LAHSO clearance if they
determine it will compromise safety.
4.To conduct LAHSO, pilots should become
familiar with all available information concerning
LAHSO at their destination airport. Pilots should
have, readily available, the published ALD and
runway slope information for all LAHSO runway
combinations at each airport of intended landing.
Additionally, knowledge about landing performancedata permits the pilot to readily determine that the
ALD for the assigned runway is sufficient for safeLAHSO. As part of a pilot’s preflight planningprocess, pilots should determine if their destination
airport has LAHSO. If so, their preflight planning
process should include an assessment of whichLAHSO combinations would work for them given
their aircraft’s required landing distance. Good pilot
decision making is knowing in advance whether one
can accept a LAHSO clearance if offered.FIG 4− 3−8
Land and Hold Short of an Intersecting Runway
EXAMPLE−
FIG 4− 3−10 − holding short at a designated point may be
required to avoid conflicts with the runway safetyarea/flight path of a nearby runway.
NOTE−
Each figure shows the approximate location of LAHSOmarkings, signage, and in −pavement lighting when
installed.
REFERENCE−
AIM, Chapter 2, Aeronautical Lighting and Other Airport Visual Aids.
FIG 4− 3−9
Land and Hold Short of an Intersecting Taxiway
AIM 10/12/17
4−3−17 Airport OperationsFIG 4− 3−10
Land and Hold Short of a Designated Point
on a Runway Other Than an Intersecting
Runway or Taxiway
5.If, for any reason, such as difficulty in
discerning the location of a LAHSO intersection,
wind conditions, aircraft condition, etc., the pilot
elects to request to land on the full length of the
runway, to land on another runway, or to decline
LAHSO, a pilot is expected to promptly inform air
traffic, ideally even before the clearance is issued. ALAHSO clearance, once accepted, must be adhered
to, just as any other ATC clearance, unless an
amended clearance is obtained or an emergencyoccurs. A LAHSO clearance does not preclude a
rejected landing.
6.A pilot who accepts a LAHSO clearance
should land and exit the runway at the first convenient
taxiway (unless directed otherwise) before reaching
the hold short point. Otherwise, the pilot must stopand hold at the hold short point. If a rejected landing
becomes necessary after accepting a LAHSO
clearance, the pilot should maintain safe separationfrom other aircraft or vehicles, and should promptly
notify the controller.
7.Controllers need a full read back of all
LAHSO clearances. Pilots should read back theirLAHSO clearance and include the words, “HOLD
SHORT OF (RUNWAY/T AXIWAY/OR POINT)” in
their acknowledgment of all LAHSO clearances. In
order to reduce frequency congestion, pilots are
encouraged to read back the LAHSO clearancewithout prompting. Don’t make the controller have to
ask for a read back!
c. LAHSO Situational Awareness
1.Situational awareness is vital to the success of
LAHSO. Situational awareness starts with havingcurrent airport information in the cockpit, readilyaccessible to the pilot. (An airport diagram assists
pilots in identifying their location on the airport, thus
reducing requests for “progressive taxi instructions”
from controllers.)
2.Situational awareness includes effective
pilot− controller radio communication. ATC expects
pilots to specifically acknowledge and read back all
LAHSO clearances as follows:
EXAMPLE−
ATC: “(Air craft ID) cleared to land runway six right, hold
short of taxiway bravo for crossing traffic (type air craft).”
Aircraft: “(Aircraft ID), wilco, cleared to land runway six
right to hold short of taxiway bravo.”
ATC: “(Aircraft ID) cross runway six right at taxiway
bravo, landing aircraft will hold short.”
Aircraft: “(Aircraft ID), wilco, cross runway six right at
bravo, landing traffic (type aircraft) to hold.”
3.For those airplanes flown with two crew-
members, effective intra −cockpit communication
between cockpit crewmembers is also critical. There
have been several instances where the pilot working
the radios accepted a LAHSO clearance but thensimply forgot to tell the pilot flying the aircraft.
4.Situational awareness also includes a thor-
ough understanding of the airport markings, signage,and lighting associated with LAHSO. These visual
aids consist of a three −part system of yellow
hold− short markings, red and white signage and, in
certain cases, in−pavement lighting. Visual aids assist
the pilot in determining where to hold short.
FIG 4− 3−8, FIG 4− 3−9, FIG 4−3−10 depict how
these markings, signage, and lighting combinations
will appear once installed. Pilots are cautioned that
not all airports conducting LAHSO have installed any
or all of the above markings, signage, or lighting.
5.Pilots should only receive a LAHSO
clearance when there is a minimum ceiling of
1,000 feet and 3 statute miles visibility. The intent of
having “basic” VFR weather conditions is to allowpilots to maintain visual contact with other aircraftand ground vehicle operations. Pilots should consider
the effects of prevailing inflight visibility (such as
landing into the sun) and how it may affect overall
AIM 10/12/17
4−3−18 Airport Operationssituational awareness. Additionally, surface vehicles
and aircraft being taxied by maintenance personnel
may also be participating in LAHSO, especially in
those operations that involve crossing an active
runway.
4−3−12. Low Approach
a.A low approach (sometimes referred to as a low
pass) is the go −around maneuver following an
approach. Instead of landing or making a touch −and−
go, a pilot may wish to go around (low approach) inorder to expedite a particular operation (a series of
practice instrument approaches is an example of such
an operation). Unless otherwise authorized by ATC,the low approach should be made straight ahead, with
no turns or climb made until the pilot has made a
thorough visual check for other aircraft in the area.
b.When operating within a Class B, Class C, and
Class D surface area, a pilot intending to make a low
approach should contact the tower for approval. This
request should be made prior to starting the finalapproach.
c.When operating to an airport, not within a
Class B, Class C, and Class D surface area, a pilot
intending to make a low approach should, prior toleaving the final approach fix inbound (nonprecision
approach) or the outer marker or fix used in lieu of the
outer marker inbound (precision approach), so advisethe FSS, UNICOM, or make a broadcast as
appropriate.
REFERENCE −
AIM, Paragraph 4 −1−9 , Traffic Advisory Practices at Airports Without
Operating Control Towers
4−3−13. Traffic Control Light Signals
a.The following procedures are used by ATCTs in
the control of aircraft, ground vehicles, equipment,and personnel not equipped with radio. These same
procedures will be used to control aircraft, ground
vehicles, equipment, and personnel equipped with
radio if radio contact cannot be established. ATC
personnel use a directive traffic control signal which
emits an intense narrow light beam of a selected color
(either red, white, or green) when controlling traffic
by light signals.
b.Although the traffic signal light offers the
advantage that some control may be exercised overnonradio equipped aircraft, pilots should be cog-
nizant of the disadvantages which are:
1.Pilots may not be looking at the control tower
at the time a signal is directed toward their aircraft.
2.The directions transmitted by a light signal
are very limited since only approval or disapproval of
a pilot’s anticipated actions may be transmitted. No
supplement or explanatory information may betransmitted except by the use of the “General
Warning Signal” which advises the pilot to be on the
alert.
c.Between sunset and sunrise, a pilot wishing to
attract the attention of the control tower should turnon a landing light and taxi the aircraft into a position,
clear of the active runway, so that light is visible to the
tower. The landing light should remain on untilappropriate signals are received from the tower.
d.Airport Traffic Control Tower Light Gun
Signals. (See TBL 4 −3−1.)
e.During daylight hours, acknowledge tower
transmissions or light signals by moving the ailerons
or rudder. At night, acknowledge by blinking the
landing or navigation lights. If radio malfunction
occurs after departing the parking area, watch thetower for light signals or monitor tower frequency.
AIM 10/12/17
4−3−19 Airport OperationsTBL 4−3−1
Airport Traffic Control Tower Light Gun Signals
Meaning
Color and Type of SignalMovement of Vehicles,
Equipment and Personnel Aircraft on the Ground Aircraft in Flight
Steady green Cleared to cross, proceed or go Cleared for takeoff Cleared to land
Flashing green Not applicable Cleared for taxi Return for landing (to befollowed by steady green at the
proper time)
Steady red STOP STOP Give way to other aircraft and
continue circling
Flashing red Clear the taxiway/runway Taxi clear of the runway in use Airport unsafe, do not land
Flashing white Return to starting point on airport Return to starting point on airport Not applicable
Alternating red and green Exercise extreme caution Exercise extreme caution Exercise extreme caution
4−3−14. Communications
a.Pilots of departing aircraft should communicate
with the control tower on the appropriate groundcontrol/clearance delivery frequency prior to starting
engines to receive engine start time, taxi and/or
clearance information. Unless otherwise advised bythe tower, remain on that frequency during taxiing
and runup, then change to local control frequency
when ready to request takeoff clearance.
NOTE−
Pilots are encouraged to monitor the local tower fr equency
as soon as practical consistent with other ATCrequirements.
REFERENCE −
AIM, Paragraph 4 −1−13 , Automatic Terminal Information Service
(ATIS)
b.The tower controller will consider that pilots of
turbine−powered aircraft are ready for takeoff when
they reach the runway or warm −up block unless
advised otherwise.
c.The majority of ground control frequencies are
in the 121.6 −121.9 MHz bandwidth. Ground control
frequencies are provided to eliminate frequency
congestion on the tower (local control) frequency and
are limited to communications between the tower andaircraft on the ground and between the tower and
utility vehicles on the airport, provide a clear VHF
channel for arriving and departing aircraft. They areused for issuance of taxi information, clearances, and
other necessary contacts between the tower and
aircraft or other vehicles operated on the airport. Apilot who has just landed should not change from thetower frequency to the ground control frequency until
directed to do so by the controller. Normally , only one
ground control frequency is assigned at an airport;
however, at locations where the amount of traffic so
warrants, a second ground control frequency and/oranother frequency designated as a clearance delivery
frequency, may be assigned.
d.A controller may omit the ground or local
control frequency if the controller believes the pilotknows which frequency is in use. If the ground
control frequency is in the 121 MHz bandwidth the
controller may omit the numbers preceding thedecimal point; e.g., 121.7, “CONTACT GROUND
POINT SEVEN.” However, if any doubt exists as to
what frequency is in use, the pilot should promptlyrequest the controller to provide that information.
e.Controllers will normally avoid issuing a radio
frequency change to helicopters, known to besingle−piloted, which are hovering, air taxiing, or
flying near the ground. At times, it may be necessary
for pilots to alert ATC regarding single pilotoperations to minimize delay of essential ATC
communications. Whenever possible, ATC instruc-
tions will be relayed through the frequency beingmonitored until a frequency change can be
accomplished. Y ou must promptly advise ATC if you
are unable to comply with a frequency change. Also,you should advise ATC if you must land to
accomplish the frequency change unless it is clear the
landing will have no impact on other air traffic;e.g., on a taxiway or in a helicopter operating area.
AIM 10/12/17
4−3−20 Airport Operations4−3−15. Gate Holding Due to Departure
Delays
a.Pilots should contact ground control or
clearance delivery prior to starting engines as gate
hold procedures will be in effect whenever departure
delays exceed or are anticipated to exceed
15 minutes. The sequence for departure will be
maintained in accordance with initial call up unlessmodified by flow control restrictions. Pilots should
monitor the ground control or clearance delivery
frequency for engine startup advisories or newproposed start time if the delay changes.
b.The tower controller will consider that pilots of
turbine−powered aircraft are ready for takeoff when
they reach the runway or warm −up block unless
advised otherwise.
4−3−16. VFR Flights in Terminal Areas
Use reasonable restraint in exercising the prerogative
of VFR flight, especially in terminal areas. The
weather minimums and dist ances from clouds are
minimums. Giving yourself a greater margin in
specific instances is just good judgment.
a. Approach Area. Conducting a VFR operation
in a Class B, Class C, Class D, and Class E surfacearea when the official visibility is 3 or 4 miles is not
prohibited, but good judgment would dictate that you
keep out of the approach area.
b. Reduced Visibility. It has always been recog-
nized that precipitation reduces forward visibility.
Consequently, although again it may be perfectly
legal to cancel your IFR flight plan at any time youcan proceed VFR, it is good practice, when
precipitation is occurring, to continue IFR operation
into a terminal area until you are reasonably close toyour destination.
c. Simulated Instrument Flights. In conducting
simulated instrument flights, be sure that the weatheris good enough to compensate for the restricted
visibility of the safety pilot and your greater
concentration on your flight instruments. Giveyourself a little greater margin when your flight plan
lies in or near a busy airway or close to an airport.
4−3−17. VFR Helicopter Operations at
Controlled Airports
a. General.1.The following ATC procedures and phrase-
ologies recognize the unique capabilities of
helicopters and were developed to improve service to
all users. Helicopter design characteristics and user
needs often require operations from movement areas
and nonmovement areas within the airport boundary.
In order for ATC to properly apply these procedures,
it is essential that pilots familiarize themselves withthe local operations and make it known to controllers
when additional instructions are necessary.
2.Insofar as possible, helicopter operations will
be instructed to avoid the flow of fixed −wing aircraft
to minimize overall delays; however, there will be
many situations where faster/larger helicopters maybe integrated with fixed −wing aircraft for the benefit
of all concerned. Examples would include IFR
flights, avoidance of noise sensitive areas, or use ofrunways/taxiways to minimize the hazardous effects
of rotor downwash in congested areas.
3.Because helicopter pilots are intimately
familiar with the effects of rotor downwash, they are
best qualified to determine if a given operation can be
conducted safely. Accordingly, the pilot has the final
authority with respect to the specific airspeed/altitude
combinations. A TC clearances are in no way intended
to place the helicopter in a hazardous position. It isexpected that pilots will advise ATC if a specific
clearance will cause undue hazards to persons or
property.
b.Controllers normall y limit A TC ground service
and instruction to movement areas; therefore,
operations from nonmovement areas are conducted at
pilot discretion and should be based on local policies,
procedures, or letters of agreement. In order to
maximize the flexibility of helicopter operations, it is
necessary to rely heavily on sound pilot judgment.
For example, hazards such as debris, obstructions,
vehicles, or personnel must be recognized by thepilot, and action should be taken as necessary to avoid
such hazards. Taxi, hover taxi, and air taxi operations
are considered to be ground movements. Helicoptersconducting such operations are expected to adhere to
the same conditions, requirements, and practices as
apply to other ground taxiing and A TC procedures in
the AIM.
1.The phraseology taxi is used when it is
intended or expected that the helicopter will taxi onthe airport surface, either via taxiways or other
prescribed routes. Taxi is used primarily for
helicopters equipped with wheels or in response to a
AIM 10/12/17
4−3−21 Airport Operationspilot request. Preference should be given to this
procedure whenever it is necessary to minimize
effects of rotor downwash.
2.Pilots may request a hover taxi when slow
forward movement is desired or when it may be
appropriate to move very short distances. Pilots
should avoid this procedure if rotor downwash is
likely to cause damage to parked aircraft or if blowing
dust/snow could obscure visibility. If it is necessaryto operate above 25 feet AGL when hover taxiing, the
pilot should initiate a request to ATC.
3.Air taxi is the preferred method for helicopter
ground movements on airports provided groundoperations and conditions permit. Unless otherwise
requested or instructed, pilots are expected to remain
below 100 feet AGL. However, if a higher thannormal airspeed or altitude is desired, the request
should be made prior to lift −off. The pilot is solely
responsible for selecting a safe airspeed for thealtitude/operation being conducted. Use of air taxi
enables the pilot to proceed at an optimum
airspeed/altitude, minimize downwash effect, con-serve fuel, and expedite movement from one point to
another. Helicopters should avoid overflight of other
aircraft, vehicles, and personnel during air −taxi
operations. Caution must be exercised concerning
active runways and pilots must be certain that air taxi
instructions are understood. Special precautions may
be necessary at unfamiliar airports or airports with
multiple/intersecting active runways. The taxi
procedures given in Paragraph 4 −3−18, Taxiing,
Paragraph 4 −3−19, Taxi During Low Visibility, and
Paragraph 4 −3−20, Exiting the Runway After
Landing, also apply.
REFERENCE −
Pilot/Controller Glossary Term − Taxi.
Pilot/Controller Glossary Term − Hover T axi.
Pilot/Controller Glossary Term − Air T axi.
c. Takeoff and Landing Procedures.
1.Helicopter operations may be conducted
from a runway, taxiway, portion of a landing strip, or
any clear area which could be used as a landing site
such as the scene of an accident, a construction site,or the roof of a building. The terms used to describe
designated areas from which helicopters operate are:
movement area, landing/takeoff area, apron/ramp,heliport and helipad (See Pilot/Controller Glossary).These areas may be improved or unimproved and
may be separate from or located on an airport/heli-
port. ATC will issue takeoff clearances from
movement areas other than active runways, or in
diverse directions from active runways, withadditional instructions as necessary. Whenever
possible, takeoff clearance will be issued in lieu of
extended hover/air taxi operations. Phraseology willbe “CLEARED FOR TAKEOFF FROM (taxiway,
helipad, runway number, etc.), MAKE RIGHT/
LEFT TURN FOR (direction, heading, NA V AIDradial) DEPARTURE/DEPARTURE ROUTE (num-
ber, name, etc.).” Unless requested by the pilot,
downwind takeoffs will not be issued if the tailwindexceeds 5 knots.
2.Pilots should be alert to wind information as
well as to wind indications in the vicinity of the
helicopter. ATC should be advised of the intended
method of departing. A pilot request to takeoff in a
given direction indicates that the pilot is willing to
accept the wind condition and controllers will honorthe request if traffic permits. Departure points could
be a significant distance from the control tower and
it may be difficult or impossible for the controller todetermine the helicopter’s relative position to the
wind.
3.If takeoff is requested from nonmovement
areas, an area not authorized for helicopter use, an
area not visible from the tower, an unlighted area atnight, or an area off the airport, the phraseology
“DEPARTURE FROM (requested location) WILL
BE AT YOUR OWN RISK (additional instructions,as necessary). USE CAUTION (if applicable).” The
pilot is responsible for operating in a safe manner and
should exercise due caution.
4.Similar phraseology is used for helicopter
landing operations. Every effort will be made to
permit helicopters to proceed direct and land as near
as possible to their final destination on the airport.Traffic density, the need for detailed taxiing
instructions, frequency congestion, or other factors
may affect the extent to which service can beexpedited. As with ground movement operations, a
high degree of pilot/controller cooperation and
communication is necessary to achieve safe andefficient operations.
AIM 10/12/17
4−3−22 Airport Operations4−3−18. Taxiing
a. General. Approval must be obtained prior to
moving an aircraft or vehicle onto the movement area
during the hours an Airport Traffic Control Tower isin operation.
1.Always state your position on the airport
when calling the tower for taxi instructions.
2.The movement area is normally described in
local bulletins issued by the airport manager or
control tower. These bulletins may be found in FSSs,
fixed base operators offices, air carrier offices, and
operations offices.
3.The control tower also issues bulletins
describing areas where they cannot provide ATC
service due to nonvisibility or other reasons.
4.A clearance must be obtained prior to taxiing
on a runway, taking off, or landing during the hours
an Airport Traffic Control Tower is in operation.
5.A clearance must be obtained prior to
crossing any runway. ATC will issue an explicit
clearance for all runway crossings.
6.When assigned a takeoff runway, ATC will
first specify the runway, issue taxi instructions, and
state any hold short instructions or runway crossing
clearances if the taxi route will cross a runway. This
does not authorize the aircraft to “enter” or “cross”
the assigned departure runway at any point. In orderto preclude misunderstandings in radio communica-
tions, ATC will not use the word “cleared” in
conjunction with authorization for aircraft to taxi.
7.When issuing taxi instructions to any point
other than an assigned takeoff runway, ATC will
specify the point to taxi to, issue taxi instructions, and
state any hold short instructions or runway crossing
clearances if the taxi route will cross a runway.
NOTE−
ATC is required to obtain a readback from the pilot of allrunway hold short instructions.
8.If a pilot is expected to hold short of a runway
approach (“APPCH”) area or ILS holding position
(see FIG 2 −3−15, Taxiways Located in Runway
Approach Area), ATC will issue instructions.
9.When taxi instructions are received from the
controller, pilots should always read back:
(a)The runway assignment.(b)Any clearance to enter a specific runway.
(c)Any instruction to hold short of a specific
runway or line up and wait.
Controllers are required to request a readback of
runway hold short assignment when it is not received
from the pilot/vehicle.
b.ATC clearances or instru ctions pertaining to
taxiing are predicated on known traffic and known
physical airport conditions. Therefore, it is important
that pilots clearly understand the clearance orinstruction. Although an ATC clearance is issued for
taxiing purposes, when operating in accordance with
the CFRs, it is the responsibility of the pilot to avoidcollision with other aircraft. Since “the pilot −in−com-
mand of an aircraft is directly responsible for, and is
the final authority as to, the operation of that aircraft”the pilot should obtain clarification of any clearance
or instruction which is not understood.
REFERENCE −
AIM, Paragraph 7 −3−1 , General
1.Good operating practice dictates that pilots
acknowledge all runway crossing, hold short, ortakeoff clearances unless there is some misunder-
standing, at which time the pilot should query the
controller until the clearance is understood.
NOTE−
Air traffic controllers are required to obtain from the pilot
a readback of all runway hold short instructions.
2.Pilots operating a single pilot aircraft should
monitor only assigned ATC communications after
being cleared onto the active runway for departure.
Single pilot aircraft should not monitor other thanATC communications until flight from Class B,
Class C, or Class D surface area is completed. This
same procedure should be practiced from after receipt
of the clearance for landing until the landing and taxi
activities are complete. Proper effective scanning for
other aircraft, surface vehicles, or other objectsshould be continuously exercised in all cases.
3.If the pilot is unfamiliar with the airport or for
any reason confusion exists as to the correct taxi
routing, a request may be made for progressive taxi
instructions which include step −by−step routing
directions. Progressive instructions may also be
issued if the controller deems it necessary due to
traffic or field conditions (for example, constructionor closed taxiways).
c.At those airports where the U.S. Government
operates the control tower and ATC has authorized
AIM 10/12/17
4−3−23 Airport Operationsnoncompliance with the requirement for two −way
radio communications while operating within the
Class B, Class C, or Class D surface area, or at those
airports where the U.S. Government does not operate
the control tower and radio communications cannotbe established, pilots must obtain a clearance by
visual light signal prior to taxiing on a runway and
prior to takeoff and landing.
d.The following phraseologies and procedures
are used in radiotelephone communications with
aeronautical ground stations.
1. Request for taxi instructions prior to
departure. State your aircraft identification, loca-
tion, type of operation planned (VFR or IFR), and the
point of first intended landing.
EXAMPLE −
Aircraft: “Washington ground, Beechcraft One Three One
Five Niner at hangar eight, ready to taxi, I −F−R to
Chicago.” Tower: “Beechcraft one three one five niner, Washington
ground, runway two seven, taxi via taxiways Charlie and
Delta, hold short of runway three three left.”
Aircraft: “Beechcraft One Three One Five Niner, hold
short of runway three three left.”
2. Receipt of ATC clearance. ARTCC clear-
ances are relayed to pilots by airport trafficcontrollers in the following manner.
EXAMPLE −
Tower: “Beechcraft One Three One Five Niner, cleared to
the Chicago Midway Airport via Victor Eight, maintaineight thousand.”
Aircraft: “Beechcraft One Three One Five Niner, cleared
to the Chicago Midway Airport via Victor Eight, maintaineight thousand.”
NOTE−
Normally, an ATC IFR clearance is relayed to a pilot by the
ground controller. At busy locations, however, pilots may
be instructed by the ground controller to “contactclearance delivery” on a frequency designated for thispurpose. No surveillance or contr ol over the movement of
traffic is exercised by this position of operation.
3. Request for taxi instructions after landing.
State your aircraft identification, location, and that
you request taxi instructions.
EXAMPLE −
Aircraft: “Dulles ground, Beechcraft One Four Two SixOne clearing runway one right on taxiway echo three,
request clearance to Page.”
Tower: “Beechcraft One Four Two Six One, Dulles
ground, taxi to Page via taxiways echo three, echo one, and
echo niner.”
or
Aircraft: “Orlando ground, Beechcraft One Four Two Six
One clearing runway one eight left at taxiway bravo three,request clearance to Page.”
Tower: “Beechcraft One Four Two Six One, Orlando
ground, hold short of runway one eight right.”
Aircraft: “Beechcraft One Four Two Six One, hold short
of runway one eight right.”
4−3−19. Taxi During Low Visibility
a.Pilots and aircraft operators should be constant-
ly aware that during certain low visibility conditions
the movement of aircraft and vehicles on airports may
not be visible to the tower controller. This mayprevent visual confirmation of an aircraft’s adherence
to taxi instructions.
b.Of vital importance is the need for pilots to
notify the controller when difficulties are encoun-
tered or at the first indication of becoming
disoriented. Pilots should proceed with extremecaution when taxiing toward the sun. When vision
difficulties are encountered pilots should immediate-
ly inform the controller.
c.Advisory Circular 120 −57, Low Visibility
Operations Surface Movement Guidance and Control
System, commonly known as LVOSMGCS (pro-nounced “LVO SMIGS”) describes an adequate
example of a low visibility taxi plan for any airport
which has takeoff or landing operations in less than
1,200 feet runway visual range (RVR) visibility
conditions. These plans, which affect aircrew andvehicle operators, may incorporate additional
lighting, markings, and procedures to control airport
surface traffic. They will be addressed at two levels;operations less than 1,200 feet RVR to 500 feet RVR
and operations less than 500 feet RVR.
NOTE−
Specific lighting systems and surface markings may befound in Paragraph 2 −1−11, Taxiway Lights, and
Paragraph 2 −3−4 , Taxiway Markings.
d.When low visibility conditions exist, pilots
should focus their entire attention on the safe
AIM 10/12/17
4−3−24 Airport Operationsoperation of the aircraft while it is moving. Checklists
and nonessential communication should be withheld
until the aircraft is stopped and the brakes set.
4−3−20. Exiting the Runway After Landing
The following procedures must be followed after
landing and reaching taxi speed.
a.Exit the runway without delay at the first
available taxiway or on a taxiway as instructed byATC. Pilots must not exit the landing runway onto
another runway unless authorized by ATC. At
airports with an operating control tower, pilots should
not stop or reverse course on the runway without first
obtaining ATC approval.
b.Taxi clear of the runway unless otherwise
directed by A TC. An aircraft is considered clear of the
runway when all parts of the aircraft are past the
runway edge and there are no restrictions to its
continued movement beyond the runway holdingposition markings. In the absence of ATC instruc-
tions, the pilot is expected to taxi clear of the landing
runway by taxiing beyond the runway holdingposition markings associated with the landing
runway, even if that requires the aircraft to protrude
into or cross another taxiway or ramp area. Once all
parts of the aircraft have crossed the runway holding
position markings, the pilot must hold unless furtherinstructions have been issued by ATC.
NOTE−
1.The tower will issue the pilot instructions which will
permit the aircraft to enter another taxiway, runway, orramp area when required.
2.Guidance contained in subparagraphs a and b above is
considered an integral part of the landing clearance and
satisfies the requirement of 14 CFR Section 91.129.
c.Immediately change to ground control frequen-
cy when advised by the tower and obtain a taxi
clearance.
NOTE−
1.The tower will issue instructions r equired to resolve any
potential conflictions with other ground traffic prior toadvising the pilot to contact ground control.
2.Ground control will issue taxi clearance to parking.
That clearance does not authorize the aircraft to “enter”
or “cross” any runways. Pilots not familiar with the taxi
route should request specific taxi instructions from ATC.4−3−21. Practice Instrument Approaches
a.Various air traffic incidents have indicated the
necessity for adoption of measures to achieve moreorganized and controlled operations where practice
instrument approaches are conducted. Practice
instrument approaches are considered to be instru-ment a pproaches made by either a VFR aircraft not on
an IFR flight plan or an aircraft on an IFR flight plan.
To achieve this and thereby enhance air safety, it isAir Traffic’s policy to provide for separation of such
operations at locations where approach control
facilities are located and, as resources permit, atcertain other locations served by ARTCCs or parent
approach control facilities. Pilot requests to practice
instrument approaches may be approved by ATCsubject to traffic and workload conditions. Pilots
should anticipate that in some instances the controller
may find it necessary to deny approval or withdrawprevious approval when traffic conditions warrant. It
must be clearly understood, however, that even
though the controller may be providing separation,
pilots on VFR flight plans are required to comply with
basic VFR weather minimums (14 CFR Sec-tion 91.155). Application of ATC procedures or any
action taken by the controller to avoid traffic
conflictions does not relieve IFR and VFR pilots oftheir responsibility to see −and−avoid other traffic
while operating in VFR conditions (14 CFR
Section 91.113). In addition to the normal IFRseparation minimu ms (which includes visual separa-
tion) during VFR conditions, 500 feet vertical
separation may be applied between VFR aircraft and
between a VFR aircraft and the IFR aircraft. Pilots not
on IFR flight plans desiring practice instrument
approaches should always state ‘practice’ whenmaking requests to ATC. Controllers will instruct
VFR aircraft requesting an instrument approach to
maintain VFR. This is to preclude misunderstandings
between the pilot and controller as to the status of the
aircraft. If pilots wish to proceed in accordance with
instrument flight rules, they must specifically request
and obtain, an IFR clearance.
b.Before practicing an instrument approach,
pilots should inform the approach control facility orthe tower of the type of practice approach they desire
to make and how they intend to terminate it,
i.e., full−stop landing, touch −and−go, or missed or
low approach maneuver. This information may be
furnished progressively when conducting a series of
approaches. Pilots on an IFR flight plan, who have
AIM 10/12/17
4−3−25 Airport Operationsmade a series of instrument approaches to full stop
landings should inform ATC when they make their
final landing. The controller will control flights
practicing instrument approaches so as to ensure that
they do not disrupt the flow of arriving and departing
itinerant IFR or VFR aircraft. The priority afforded
itinerant aircraft over practice instrument approaches
is not intended to be so rigidly applied that it causesgrossly inefficient application of services. A
minimum delay to itinerant traffic may be appropriate
to allow an aircraft practicing an approach tocomplete that approach.
NOTE−
A clearance to land means that appropriate separation onthe landing runway will be ensured. A landing clearancedoes not relieve the pilot from compliance with anypreviously issued restriction.
c.At airports without a tower, pilots wishing to
make practice instrument approaches should notify
the facility having control jurisdiction of the desired
approach as indicated on the approach chart. Allapproach control facilities and ARTCCs are required
to publish a Letter to Airmen depicting those airports
where they provide standard separation to both VFRand IFR aircraft conducting practice instrument
approaches.
d.The controller will provide approved separation
between both VFR and IFR aircraft when authoriza-
tion is granted to make practice approaches to airports
where an approach control facility is located and tocertain other airports served by approach control or
an ARTCC. Controller responsibility for separation
of VFR aircraft begins at the point where theapproach clearance becomes effective, or when the
aircraft enters Class B or Class C airspace, or a TRSA,
whichever comes first.
e.VFR aircraft practicing instrument approaches
are not automatically authorized to execute the
missed approach procedure. This authorization mustbe specifically requested by the pilot and approved by
the controller. Separation will not be provided unless
the missed approach has been approved by ATC.
f.Except in an emergency, aircraft cleared to
practice instrument approaches must not deviate from
the approved procedure until cleared to do so by the
controller.
g.At radar approach control locations when a full
approach procedure (procedure turn, etc.,) cannot beapproved, pilots should expect to be vectored to a
final approach course for a practice instrument
approach which is compatible with the general
direction of traffic at that airport.
h.When granting approval for a practice
instrument approach, the controller will usually ask
the pilot to report to the tower prior to or over the finalapproach fix inbound (nonprecision approaches) or
over the outer marker or fix used in lieu of the outer
marker inbound (precision approaches).
i.When authorization is granted to conduct
practice instrument approaches to an airport with atower, but where approved standard separation is not
provided to aircraft conducting practice instrument
approaches, the tower will approve the practiceapproach, instruct the aircraft to maintain VFR and
issue traffic information, as required.
j.When an aircraft notifies a FSS providing Local
Airport Advisory to the airport concerned of the
intent to conduct a practice instrument approach andwhether or not separation is to be provided, the pilot
will be instructed to contact the appropriate facility
on a specified frequency prior to initiating theapproach. At airports where separation is not
provided, the FSS will acknowledge the message and
issue known traffic information but will neitherapprove or disapprove the approach.
k.Pilots conducting practice instrument ap-
proaches should be particularly alert for other aircraft
operating in the local traf fic pattern or in proximity to
the airport.
4−3−22. Option Approach
The “Cleared for the Option” procedure will permit
an instructor, flight examiner or pilot the option to
make a touch −and−go, low approach, missed
approach, stop −and−go, or full stop landing. This
procedure can be very beneficial in a training
situation in that neither the student pilot nor examinee
would know what maneuver would be accomplished.
The pilot should make a request for this procedure
passing the final approach fix inbound on an
instrument approach or entering downwind for a VFR
traffic pattern. After ATC approval of the option, the
pilot should inform ATC as soon as possible of any
delay on the runway during their stop-and-go or fullstop landing. The advantages of this procedure as a
training aid are that it enables an instructor or
examiner to obtain the reaction of a trainee or
AIM 10/12/17
4−3−26 Airport Operationsexaminee under changing conditions, the pilot would
not have to discontinue an approach in the middle of
the procedure due to student error or pilot proficiency
requirements, and finally it allows more flexibility
and economy in training programs. This procedurewill only be used at those locations with an
operational control tower and will be subject to ATC
approval.
4−3−23. Use of Aircraft Lights
a.Aircraft position lights
are required to be lighted
on aircraft operated on the surface and in flight from
sunset to sunrise. In addition, aircraft equipped withan anti−collision light
system are required to operate
that light system during all types of operations (day
and night). However, during any adverse meteorolog-ical conditions, the pilot −in−command may
determine that the anti −collision lights should be
turned off when their light output would constitute ahazard to safety (14 CFR Section 91.209).
Supplementary strobe lights should be turned off on
the ground when they adversely affect groundpersonnel or other pilots, and in flight when there are
adverse reflection from clouds.
b.An aircraft anti −collision light system can use
one or more rotating beacons and/or strobe lights, be
colored either red or white, and have dif ferent (higher
than minimum) intensities when compared to other
aircraft. Many aircraft have both a rotating beacon
and a strobe light system.
c.The FAA has a voluntary pilot safety program,
Operation Lights On, to enhance the see−and−avoid
concept. Pilots are encouraged to turn on their landing
lights during takeoff; i.e., either after takeoff
clearance has been received or when beginningtakeoff roll. Pilots are further encouraged to turn on
their landing lights when operating below
10,000 feet, day or night, especially when operatingwithin 10 miles of any airport, or in conditions of
reduced visibility and in areas where flocks of birds
may be expected, i.e., coastal areas, lake areas,around refuse dumps, etc. Although turning on
aircraft lights does enhance the see−and−avoid
concept, pilots should not become complacent aboutkeeping a sharp lookout for other aircraft. Not all
aircraft are equipped with lights and some pilots may
not have their lights turned on. Aircraft manufactur-er’s recommendations for operation of landing lights
and electrical systems should be observed.
d.Prop and jet blast forces generated by large
aircraft have overturned or damaged several smaller
aircraft taxiing behind them. To avoid similar results,
and in the interest of preventing upsets and injuries to
ground personnel from such forces, the FAA
recommends that air carriers and commercialoperators turn on their rotating beacons anytime their
aircraft engines are in operation. General aviation
pilots using rotating beacon equipped aircraft are also
encouraged to participate in this program which is
designed to alert others to the potential hazard. Since
this is a voluntary program, exercise caution and donot rely solely on the rotating beacon as an indication
that aircraft engines are in operation.
e.Prior to commencing taxi, it is recommended to
turn on navigation, position, anti-collision, and logo
lights (if equipped). To signal intent to other pilots,
consider turning on the taxi light when the aircraft is
moving or intending to move on the ground, and
turning it off when stopped or yielding to other
ground traffic. Strobe lights should not be illuminated
during taxi if they will adversely affect the vision of
other pilots or ground personnel.
f.At the discretion of the pilot-in-command, all
exterior lights should be illuminated when taxiing on
or across any runway. This increases the conspicu-
ousness of the aircraft to controllers and other pilotsapproaching to land, taxiing, or crossing the runway.
Pilots should comply with any equipment operating
limitations and consider the effects of landing andstrobe lights on other aircraft in their vicinity.
g.When entering the departure runway for takeoff
or to “line up and wait,” all lights, except for landing
lights, should be illuminated to make the aircraft
conspicuous to ATC and other aircraft on approach.
Landing lights should be turned on when takeoff
clearance is received or when commencing takeoff
roll at an airport without an operating control tower.
4−3−24. Flight Inspection/‘Flight Check’
Aircraft in Terminal Areas
a.Flight check is a call sign used to alert pilots and
air traffic controllers when a FAA aircraft is engagedin flight inspection/certification of NA V AIDs and
flight procedures. Flight check aircraft fly preplanned
high/low altitude flight patterns such as grids, orbits,
AIM 10/12/17
4−3−27 Airport OperationsDME arcs, and tracks, including low passes along the
full length of the runway to verify NA V AID
performance.
b.Pilots should be especially watchful and avoid
the flight paths of any aircraft using the call sign“Flight Check.” These flights will normally receive
special handling from ATC. Pilot patience and
cooperation in allowing uninterrupted recordings can
significantly help expedite flight inspections, mini-
mize costly, repetitive runs, and reduce the burden on
the U.S. taxpayer.
4−3−25. Hand Signals
FIG 4−3−11
Signalman Directs Towing
SIGNALMANSIGNALMANFIG 4−3−12
Signalman’s Position
SIGNALMANSIGNALMAN
FIG 4−3−13
All Clear
(O.K.)
AIM 10/12/17
4−3−28 Airport OperationsFIG 4−3−14
Start Engine
POINT
TOENGINETO BESTARTED
FIG 4−3−15
Pull ChocksFIG 4−3−16
Proceed Straight Ahead
FIG 4−3−17
Left Turn
AIM 10/12/17
4−3−29 Airport OperationsFIG 4−3−18
Right Turn
FIG 4−3−19
Slow DownFIG 4−3−20
Flagman Directs Pilot
FIG 4−3−21
Insert Chocks
AIM 10/12/17
4−3−30 Airport OperationsFIG 4−3−22
Cut Engines
FIG 4−3−23
Night Operation
Use same hand movements
as day operationFIG 4−3−24
Stop
AIM 10/12/17
4−3−31 Airport Operations4−3−26. Operations at Uncontrolled
Airports With Automated SurfaceObserving System (ASOS)/AutomatedWeather Sensor System(AWSS)/AutomatedWeather Observing System (AWOS)
a.Many airports throughout the National
Airspace System are equipped with either ASOS,
AWSS, or A WOS. At most airports with an operating
control tower or human observer, the weather will be
available to you in an Aviation Routine Weather
Report (METAR) hourly or special observation
format on the Automatic Terminal InformationService (ATIS) or directly transmitted from the
controller/observer.
b.At uncontrolled airports that are equipped with
ASOS/AWSS/AWOS with ground −to−air broadcast
capability, the one −minute updated airport weather
should be available to you within approximately 25
NM of the airport below 10,000 feet. The frequencyfor the weather broadcast will be published on
sectional charts and in the Chart Supplement U.S.
Some part −time towered airports may also broadcast
the automated weather on their ATIS frequency
during the hours that the tower is closed.c.Controllers issue SVFR or IFR clearances
based on pilot request, known traffic and reported
weather, i.e., MET AR/Nonroutine (Special) Aviation
Weather Report (SPECI) observations, when they are
available. Pilots have access to more current weather
at uncontrolled ASOS/AWSS/AWOS airports than
do the controllers who may be located several miles
away. Controllers will rely on the pilot to determinethe current airport weather from the ASOS/AWSS/
AWOS. All aircraft arriving or departing an
ASOS/AWSS/AWOS equipped uncontrolled airportshould monitor the airport weather frequency to
ascertain the status of the airspace. Pilots in Class E
airspace must be alert for changing weatherconditions which may af fect the status of the airspace
from IFR/VFR. If ATC service is required for
IFR/SVFR approach/departure or requested for VFR
service, the pilot should advise the controller that
he/she has received the one −minute weather and state
his/her intentions.
EXAMPLE −
“I have the (airport) one −minute weather, request an ILS
Runway 14 approach.”
REFERENCE −
AIM, Paragraph 7 −1−12 , Weather Observing Programs
AIM 10/12/17
4−4−1 ATC Clearances and Aircraft SeparationSection 4. ATC Clearances and Aircraft Separation
4−4−1. Clearance
a.A clearance issued by ATC is predicated on
known traffic and know n physical airport conditions.
An ATC clearance means an authorization by ATC,
for the purpose of preventing collision between
known aircraft, for an aircraft to proceed underspecified conditions within controlled airspace. IT IS
NOT AUTHORIZATION FOR A PILOT TO
DEVIATE FROM ANY RULE, REGULATION, OR
MINIMUM ALTITUDE NOR TO CONDUCT
UNSAFE OPERATION OF THE AIRCRAFT.
b.14 CFR Section 91.3(a) states: “The pilot −in−
command of an aircraft is directly responsible for,and is the final authority as to, the operation of that
aircraft.” If ATC issues a clearance that would cause
a pilot to deviate from a rule or regulation, or in the
pilot’s opinion, would place the aircraft in jeopardy,
IT IS THE PILOT’S RESPONSIBILITY TOREQUEST AN AMENDED CLEARANCE. Simi-
larly, if a pilot prefers to follow a different course of
action, such as make a 360 degree turn for spacing to
follow traffic when established in a landing or
approach sequence, land on a different runway,
takeoff from a different inte rsection, takeoff from the
threshold instead of an intersection, or delay
operation, THE PILOT IS EXPECTED TO
INFORM ATC ACCORDINGLY . When the pilotrequests a different course of action, however, the
pilot is expected to cooperate so as to preclude
disruption of traffic flow or creation of conflictingpatterns. The pilot is also expected to use
the appropriate aircraft call sign to acknowledge all
ATC clearances, frequency changes, or advisoryinformation.
c.Each pilot who deviates from an A TC clearance
in response to a T raffic Alert and Collision A voidance
System resolution advisory must notify ATC of that
deviation as soon as possible.
REFERENCE −
Pilot/Controller Glossary Term − Traffic Alert and Collision Avoidance
System.
d.When weather conditions permit, during the
time an IFR flight is operating, it is the direct
responsibility of the pilot to avoid other aircraft since
VFR flights may be operating in the same areawithout the knowledge of ATC. Traffic clearancesprovide standard separation only between IFR
flights.
4−4−2. Clearance Prefix
A clearance, control information, or a response to a
request for information originated by an ATC facility
and relayed to the pilot through an air −to−ground
communication station will be prefixed by “ATC
clears,” “ATC advises,” or “ATC requests.”
4−4−3. Clearance Items
ATC clearances normally contain the following:
a. Clearance Limit. The traffic clearance issued
prior to departure will normally authorize flight to the
airport of intended landing. Many airports andassociated NA V AIDs are collocated with the same
name and/or identifier, so care should be exercised to
ensure a clear understanding of the clearance limit.When the clearance limit is the airport of intended
landing, the clearance should contain the airport
name followed by the word “airport.” Under certainconditions, a clearance limit may be a NA V AID or
other fix. When the clearance limit is a NA V AID,
intersection, or waypoint and the type is known, theclearance should contain type. Under certain
conditions, at some locations a short −range clearance
procedure is utilized whereby a clearance is issued to
a fix within or just outside of the terminal area and
pilots are advised of the frequency on which they will
receive the long −range clearance direct from the
center controller.
b. Departure Procedure. Headings to fly and
altitude restrictions may be issued to separate a
departure from other air traffic in the terminal area.
Where the volume of traffic warrants, DPs have been
developed.
REFERENCE −
AIM, Paragraph 5 −2−5, Abbreviated IFR Departure Clearance
(Cleared. . .as Filed) Procedures
AIM, Paragraph 5 −2−8 , Instrument Departure Procedures (DP) −
Obstacle Departure Procedures (ODP) and Standard Instrument
Departures (SID)
c. Route of Flight.
1.Clearances are normally issued for the
altitude or flight level and route filed by the pilot.
However, due to traffic conditions, it is frequentlynecessary for ATC to specify an altitude or flight level
AIM 10/12/17
4−4−2 ATC Clearances and Aircraft Separationor route different from that requested by the pilot. In
addition, flow patterns have been established in
certain congested areas or between congested areas
whereby traffic capacity is increased by routing all
traffic on preferred routes. Information on these flow
patterns is available in offices where preflight
briefing is furnished or where flight plans are
accepted.
2.When required, air traffic clearances include
data to assist pilots in identifying radio reportingpoints. It is the responsibility of pilots to notify ATC
immediately if their radio equipment cannot receive
the type of signals they must utilize to comply withtheir clearance.
d. Altitude Data.
1.The altitude or flight level instructions in an
ATC clearance normally require that a pilot
“MAINTAIN” the altitude or flight level at which the
flight will operate when in controlled airspace.Altitude or flight level changes while en route should
be requested prior to the time the change is desired.
2.When possible, if the altitude assigned is
different from the altitude requested by the pilot, ATC
will inform the pilot when to expect climb or descent
clearance or to request altitude change from another
facility. If this has not been received prior to crossing
the boundary of the ATC facility’s area andassignment at a different altitude is still desired, the
pilot should reinitiate the request with the next
facility.
3.The term “cruise” may be used instead of
“MAINTAIN” to assign a block of airspace to a pilot
from the minimum IFR altitude up to and including
the altitude specified in the cruise clearance. The pilotmay level off at any intermediate altitude within this
block of airspace. Climb/descent within the block is
to be made at the discretion of the pilot. However,once the pilot starts descent and verbally reports
leaving an altitude in the block, the pilot may not
return to that altitude without additional ATCclearance.
REFERENCE −
Pilot/Controller Glossary Term − Cruise.
e. Holding Instructions.
1.Whenever an aircraft has been cleared to a fix
other than the destination airport and delay is
expected, it is the responsibility of the ATC controller
to issue complete holding instructions (unless thepattern is charted), an EFC time, and a best estimate
of any additional en route/terminal delay.
2.If the holding pattern is charted and the
controller doesn’t issue complete holding instruc-
tions, the pilot is expected to hold as depicted on the
appropriate chart. When the pattern is charted, the
controller may omit all holding instructions except
the charted holding direction and the statementAS PUBLISHED , e.g., “HOLD EAST AS
PUBLISHED.” Controllers must always issue
complete holding instructions when pilots requestthem.
NOTE−
Only those holding patterns depicted on U.S. governmentor commercially produced charts which meet F AArequirements should be used.
3.If no holding pattern is charted and holding
instructions have not been issued, the pilot should ask
ATC for holding instructions prior to reaching the fix.
This procedure will eliminate the possibility of an
aircraft entering a holding pattern other than thatdesired by ATC. If unable to obtain holding
instructions prior to reaching the fix (due to
frequency congestion, stuck microphone, etc.), holdin a standard pattern on the course on which you
approached the fix and request further clearance as
soon as possible. In this event, the altitude/flight level
of the aircraft at the clearance limit will be protected
so that separation will be provided as required.
4.When an aircraft is 3 minutes or less from a
clearance limit and a clearance beyond the fix has not
been received, the pilot is expected to start a speed
reduction so that the aircraft will cross the fix,
initially, at or below the maximum holding airspeed.
5.When no delay is expected, the controller
should issue a clearance beyond the fix as soon as
possible and, whenever possible, at least 5 minutes
before the aircraft reaches the clearance limit.
6.Pilots should report to ATC the time and
altitude/flight level at which the aircraft reaches the
clearance limit and report leaving the clearance limit.
NOTE−
In the event of two −way communications failure, pilots are
required to comply with 14 CFR Section 91.185.
4−4−4. Amended Clearances
a.Amendments to the initial clearance will be
issued at any time an air traf fic controller deems such
AIM 10/12/17
4−4−3 ATC Clearances and Aircraft Separationaction necessary to avoid possible confliction
between aircraft. Clearances will require that a flight
“hold” or change altitude prior to reaching the point
where standard separation from other IFR traffic
would no longer exist.
NOTE−
Some pilots have questioned this action and requested
“traffic information” and were at a loss when the replyindicated “no traffic report.” In such cases the controllerhas taken action to prevent a traffic confliction whichwould have occurred at a distant point.
b.A pilot may wish an explanation of the handling
of the flight at the time of occurrence; however,
controllers are not able to take time from theirimmediate control duties nor can they afford to
overload the ATC communications channels to
furnish explanations. Pilots may obtain an explana-tion by directing a letter or telephone call to the chief
controller of the facility involved.
c.Pilots have the privilege of requesting a
different clearance from that which has been issued
by A TC if they feel that they have information whichwould make another course of action more
practicable or if aircraft equipment limitations or
company procedures forbid compliance with theclearance issued.
4−4−5. Coded Departure Route (CDR)
a.CDRs provide air traffic control a rapid means
to reroute departing aircraft when the filed route is
constrained by either weather or congestion.
b.CDRs consist of an eight −character designator
that represents a route of flight. The first three
alphanumeric characters represent the departureairport, characters four through six represent the
arrival airport, and the last two characters are chosen
by the overlying ARTCC. For example, PITORDN1is an alternate route from Pittsburgh to Chicago.
Participating aircrews may then be re −cleared by air
traffic control via the CDR abbreviated clearance,PITORDN1.
c.CDRs are updated on the 56 day charting cycle.
Participating aircrews must ensure that their CDR is
current.
d.Traditionally, CDRs have been used by air
transport companies that have signed a Memorandum
of Agreement with the local air traffic control facility.
General aviation customers who wish to participate inthe program may now enter “CDR Capable” in the
remarks section of their flight plan.
e.When “CDR Capable” is entered into the
remarks section of the flight plan the general aviation
customer communicates to A TC the ability to decode
the current CDR into a flight plan route and the
willingness to fly a different route than that which
was filed.
4−4−6. Special VFR Clearances
a.An ATC clearance must be obtained prior to
operating within a Class B, Class C, Class D, orClass E surface area when the weather is less than that
required for VFR flight. A VFR pilot may request and
be given a clearance to enter, leave, or operate withinmost Class D and Class E surface areas and some
Class B and Class C surface areas in special VFR
conditions, traffic permitting, and providing suchflight will not delay IFR operations. All special VFR
flights must remain clear of clouds. The visibility
requirements for special VFR aircraft (other thanhelicopters) are:
1.At least 1 statute mile flight visibility for
operations within Class B, Class C, Class D, and
Class E surface areas.
2.At least 1 statute mile ground visibility if
taking off or landing. If ground visibility is not
reported at that airport, the flight visibility must be at
least 1 statute mile.
3.The restrictions in subparagraphs 1 and 2 do
not apply to helicopters. Helicopters must remainclear of clouds and may operate in Class B, Class C,
Class D, and Class E surface areas with less than
1 statute mile visibility.
b.When a control tower is located within the
Class B, Class C, or Class D surface area, requests for
clearances should be to the tower . In a Class E surface
area, a clearance may be obtained from the nearest
tower, FSS, or center.
c.It is not necessary to file a complete flight plan
with the request for clearance, but pilots should state
their intentions in sufficient detail to permit ATC tofit their flight into the traffic flow. The clearance will
not contain a specific altitude as the pilot must remain
clear of clouds. The controller may require the pilotto fly at or below a certain altitude due to other traf fic,
but the altitude specified will permit flight at or above
the minimum safe altitude. In addition, at radar
AIM 10/12/17
4−4−4 ATC Clearances and Aircraft Separationlocations, flights may be vectored if necessary for
control purposes or on pilot request.
NOTE−
The pilot is responsible for obstacle or terrain clearance.
REFERENCE −
14 CFR Section 91.119, Minimum safe altitudes: General.
d.Special VFR clearances are effective within
Class B, Class C, Class D, and Class E surface areas
only. ATC does not provide separation after anaircraft leaves the Class B, Class C, Class D, or
Class E surface area on a special VFR clearance.
e.Special VFR operations by fixed −wing aircraft
are prohibited in some Class B and Class C surface
areas due to the volume of IFR traffic. A list of these
Class B and Class C surface areas is contained in14 CFR Part 91, Appendix D, Section 3. They are
also depicted on sectional aeronautical charts.
f.ATC provides separation between Special VFR
flights and between these flights and other IFR
flights.
g.Special VFR operations by fixed −wing aircraft
are prohibited between sunset and sunrise unless the
pilot is instrument rated and the aircraft is equippedfor IFR flight.
h.Pilots arriving or departing an uncontrolled
airport that has automated weather broadcastcapability (ASOS/AWSS/AWOS) should monitor
the broadcast frequency, advise the controller that
they have the “one −minute weather” and state
intentions prior to operating within the Class B, Class
C, Class D, or Class E surface areas.
REFERENCE −
Pilot/Controller Glossary Term − One−minute W eather.
4−4−7. Pilot Responsibility upon Clearance
Issuance
a. Record ATC clearance. When conducting an
IFR operation, make a written record of your
clearance. The specified conditions which are a part
of your air traffic clearance may be somewhatdifferent from those included in your flight plan.
Additionally, ATC may find it necessary to ADD
conditions, such as particular departure route. Thevery fact that ATC specifies different or additional
conditions means that other aircraft are involved in
the traffic situation.b. ATC Clearance/Instruction Readback.
Pilots of airborne aircraft should read back
those parts of ATC clearances and instructions
containing altitude assignments, vectors, or runway
assignments as a means of mutual verification. Theread back of the “numbers” serves as a double check
between pilots and controllers and reduces the kinds
of communications errors that occur when a numberis either “misheard” or is incorrect.
1.Include the aircraft identification in all
readbacks and acknowledgments. This aids control-lers in determining that the correct aircraft received
the clearance or instruction. The requirement to
include aircraft identification in all readbacks andacknowledgements becomes more important as
frequency congestion increases and when aircraft
with similar call signs are on the same frequency.
EXAMPLE −
“Climbing to Flight Level three three zero, United T welve”
or “November Five Charlie Tango, roger, cleared to landrunway nine left.”
2.Read back altitudes, altitude restrictions, and
vectors in the same sequence as they are given in the
clearance or instruction.
3.Altitudes contained in charted procedures,
such as DPs, instrument approaches, etc., should not
be read back unless they are specifically stated by thecontroller.
4.Initial read back of a taxi, departure or landing
clearance should include the runway assignment,including left, right, center, etc. if applicable.
c.It is the responsibility of the pilot to accept or
refuse the clearance issued.
4−4−8. IFR Clearance VFR −on−top
a.A pilot on an IFR flight plan operating in VFR
weather conditions, may request VFR −on−top in lieu
of an assigned altitude. This permits a pilot to select
an altitude or flight level of their choice (subject toany ATC restrictions.)
b.Pilots desiring to climb through a cloud, haze,
smoke, or other meteorological formation and theneither cancel their IFR flight plan or operate
VFR-on-top may request a climb to VFR-on-top. The
ATC authorization must contain either a top report ora statement that no top report is available, and a
request to report reaching VFR-on-top. Additionally,
the A TC authorization may contain a clearance limit,
AIM 10/12/17
4−4−5 ATC Clearances and Aircraft Separationrouting and an alternative clearance if VFR −on−top
is not reached by a specified altitude.
c.A pilot on an IFR flight plan, operating in VFR
conditions, may request to climb/descend in VFR
conditions.
d.ATC may not authorize VFR −on−top/VFR
conditions operations unless the pilot requests theVFR operation or a clearance to operate in VFR
conditions will result in noise abatement benefits
where part of the IFR departure route does notconform to an FAA approved noise abatement route
or altitude.
e.When operating in VFR conditions with an ATC
authorization to “maintain VFR −on−top/maintain
VFR conditions” pilots on IFR flight plans must:
1.Fly at the appropriate VFR altitude as
prescribed in 14 CFR Section 91.159.
2.Comply with the VFR visibility and distance
from cloud criteria in 14 CFR Section 91.155 (Basic
VFR Weather Minimums).
3.Comply with instrument flight rules that are
applicable to this flight; i.e., minimum IFR altitudes,
position reporting, radio communications, course to
be flown, adherence to ATC clearance, etc.
NOTE−
Pilots should advise ATC prior to any altitude change to
ensure the exchange of accurate traffic information.
f.ATC authorization to “maintain VFR −on−top”
is not intended to restrict pilots so that they must
operate only above an obscuring meteorological
formation (layer). Instead, it permits operation above,
below, between layers, or in areas where there is no
meteorological obscuration. It is imperative, howev-
er, that pilots understand that clearance to operate“VFR−on−top/VFR conditions” does not imply
cancellation of the IFR flight plan.
g.Pilots operating VFR −on−top/VFR conditions
may receive traffic information from ATC on other
pertinent IFR or VFR aircraft. However, aircraft
operating in Class B airspace/TRSAs must beseparated as required by FAA Order JO 7110.65,
Air Traffic Control.
NOTE−
When operating in VFR weather conditions, it is the pilot’ s
responsibility to be vigilant so as to see −and−avoid other
aircraft.h.ATC will not authorize VFR or VFR −on−top
operations in Class A airspace.
REFERENCE −
AIM, Paragraph 3 −2−2 , Class A Airspace
4−4−9. VFR/IFR Flights
A pilot departing VFR, either intending to or needing
to obtain an IFR clearance en route, must be aware of
the position of the aircraft and the relative
terrain/obstructions. When accepting a clearancebelow the MEA/MIA/MV A/OROCA, pilots are
responsible for their own terrain/obstruction clear-
ance until reaching the MEA/MIA/MV A/OROCA. If
pilots are unable to maintain terrain/obstruction
clearance, the controller should be advised and pilots
should state their intentions.
NOTE−
OROCA is an off −route altitude which provides obstruc-
tion clearance with a 1,000 foot buffer in nonmountainous
terrain areas and a 2,000 foot buffer in designatedmountainous areas within the U.S. This altitude may notprovide signal coverage from ground−based navigational
aids, air traffic control radar, or communications
coverage.
4−4−10. Adherence to Clearance
a.When air traffic clearance has been obtained
under either visual or instrument flight rules, the
pilot−in−command of the aircraft must not deviate
from the provisions thereof unless an amendedclearance is obtained. When ATC issues a clearance
or instruction, pilots are expected to execute its
provisions upon receipt. ATC, in certain situations,will include the word “IMMEDIATELY” in a
clearance or instruction to impress urgency of an
imminent situation and expeditious compliance by
the pilot is expected and necessary for safety. The
addition of a VFR or other restriction; i.e., climb ordescent point or time, crossing altitude, etc., does not
authorize a pilot to deviate from the route of flight or
any other provision of the ATC clearance.
b.When a heading is assigned or a turn is
requested by ATC, pilots are expected to promptly
initiate the turn, to complete the turn, and maintain the
new heading unless issued additional instructions.
c.The term “AT PILOT’S DISCRETION”
included in the altitude information of an ATC
clearance means that ATC has offered the pilot the
option to start climb or descent when the pilot wishes,
AIM 10/12/17
4−4−6 ATC Clearances and Aircraft Separationis authorized to conduct the climb or descent at any
rate, and to temporarily level off at any intermediate
altitude as desired. However, once the aircraft has
vacated an altitude, it may not return to that altitude.
d.When A TC has not used the term “A T PILOT’S
DISCRETION” nor imposed any climb or descentrestrictions, pilots should initiate climb or descent
promptly on acknowledgement of the clearance.
Descend or climb at an optimum rate consistent with
the operating characteristics of the aircraft to
1,000 feet above or below the assigned altitude, and
then attempt to descend or climb at a rate of between
500 and 1,500 fpm until the assigned altitude is
reached. If at anytime the pilot is unable to climb ordescend at a rate of at least 500 feet a minute, advise
ATC. If it is necessary to level off at an intermediate
altitude during climb or descent, advise ATC, except
when leveling off at 10,000 feet MSL on descent, or
2,500 feet above airport elevation (prior to entering a
Class C or Class D surface area), when required forspeed reduction.
REFERENCE −
14 CFR Section 91.117.
NOTE−
Leveling off at 10,000 feet MSL on descent or 2,500 feetabove airport elevation (prior to entering a Class C orClass D surface area) to comply with 14 CFR
Section 91.117 airspeed restrictions is commonplace.
Controllers anticipate this action and plan accordingly.Leveling off at any other time on climb or descent mayseriously affect air traffic handling by ATC. Consequently,
it is imperative that pilots make every effort to fulfill the
above expected actions to aid ATC in safely handling and
expediting traffic.
e.If the altitude information of an ATC
DESCENT clearance includes a provision to
“CROSS (fix) AT” or “AT OR ABOVE/BELOW(altitude),” the manner in which the descent is
executed to comply with the crossing altitude is at the
pilot’s discretion. This authorization to descend at
pilot’s discretion is only applicable to that portion of
the flight to which the crossing altitude restrictionapplies, and the pilot is expected to comply with the
crossing altitude as a provision of the clearance. Any
other clearance in which pilot execution is optionalwill so state “AT PILOT’S DISCRETION.”
EXAMPLE −
1.“United Four Seventeen, descend and maintain
six thousand.”NOTE−
1.The pilot is expected to commence descent upon r eceipt
of the clearance and to descend at the suggested rates untilreaching the assigned altitude of 6,000 feet.
EXAMPLE −
2.“United Four Seventeen, descend at pilot’ s discretion,
maintain six thousand.”
NOTE−
2.The pilot is authorized to conduct descent within the
context of the term at pilot’ s discretion as described above.
EXAMPLE −
3.“United Four Seventeen, cr oss Lakeview V −O−R at or
above Flight Level two zero zero, descend and maintainsix thousand.”
NOTE−
3.The pilot is authorized to conduct descent at pilot’ s
discretion until reaching Lakeview VOR and must comply
with the clearance provision to cross the Lakeview VOR at
or above FL 200. After passing Lakeview VOR, the pilot isexpected to descend at the suggested rates until reachingthe assigned altitude of 6,000 feet.
EXAMPLE −
4.“United Four Seventeen, cross Lakeview V −O−R at
six thousand, maintain six thousand.”
NOTE−
4.The pilot is authorized to conduct descent at pilot’ s
discretion, however, must comply with the clearanceprovision to cross the Lakeview VOR at 6,000 feet.
EXAMPLE −
5.“United Four Seventeen, descend now to Flight
Level two seven zer o, cross Lakeview V −O−R at or below
one zero thousand, descend and maintain six thousand.”
NOTE−
5.The pilot is expected to promptly execute and complete
descent to FL 270 upon receipt of the clearance. Afterreaching FL 270 the pilot is authorized to descend “atpilot’ s discretion” until reaching Lakeview VOR. The pilot
must comply with the clearance provision to cross
Lakeview VOR at or below 10,000 feet. After LakeviewVOR the pilot is expected to descend at the suggested ratesuntil reaching 6,000 feet.
EXAMPLE −
6.“United Three Ten, descend now and maintain Flight
Level two four zero, pilot’ s discretion aft er reaching Flight
Level two eight zero.”
NOTE−
6.The pilot is expected to commence descent upon r eceipt
of the clearance and to descend at the suggested rates untilreaching FL 280. At that point, the pilot is authorized tocontinue descent to FL 240 within the context of the term“at pilot’ s discretion” as described above.
f.In case emergency authority is used to deviate
from provisions of an ATC clearance, the pilot −in−
AIM 10/12/17
4−4−7 ATC Clearances and Aircraft Separationcommand must notify ATC as soon as possible and
obtain an amended clearance. In an emergency
situation which does not result in a deviation from the
rules prescribed in 14 CFR Part 91 but which requires
ATC to give priority to an aircraft, the pilot of suchaircraft must, when requested by ATC, make a report
within 48 hours of such emergency situation to the
manager of that ATC facility.
g.The guiding principle is that the last ATC
clearance has precedence over the previous ATCclearance. When the route or altitude in a previously
issued clearance is amended, the controller will
restate applicable altitude restrictions. If altitude to
maintain is changed or restated, whether prior to
departure or while airborne, and previously issuedaltitude restrictions are omitted, those altitude
restrictions are canceled, including departure proce-
dures and STAR altitude restrictions.
EXAMPLE −
1.A departure flight receives a clearance to destination
airport to maintain FL 290. The clearance incorporates a
DP which has certain altitude crossing r estrictions. Shortly
after takeoff, the flight receives a new clearance changing
the maintaining FL from 290 to 250. If the altituderestrictions are still applicable, the controller restates
them.
2.A departing aircraft is cleared to cross Fluky
Intersection at or above 3,000 feet, Gordonville V OR at or
above 12,000 feet, maintain FL 200. Shortly after
departure, the altitude to be maintained is changed to
FL 240. If the altitude restrictions are still applicable, thecontroller issues an amended clearance as follows: “cross
Fluky Intersection at or above three thousand, cross
Gordonville V −O−R at or above one two thousand,
maintain Flight Level two four zero.”
3.An arriving aircraft is cleared to the destination airport
via V45 Delta VOR direct; the aircraft is cleared to crossDelta VOR at 10,000 feet, and then to maintain 6,000 feet.
Prior to Delta VOR, the controller issues an amended
clearance as follows: “turn right heading one eight zerofor vector to runway three six I−L−S appr oach, maintain
six thousand.”
NOTE−
Because the altitude restriction “cross Delta V −O−R at
10,000 feet” was omitted from the amended clearance, it is
no longer in effect.
h.Pilots of turbojet aircraft equipped with
afterburner engines should advise ATC prior to
takeoff if they intend to use afterburning during their
climb to the en route altitude. Often, the controllermay be able to plan traffic to accommodate a high
performance climb and allow the aircraft to climb to
the planned altitude without restriction.
i.If an “expedite” climb or descent clearance is
issued by ATC, and the altitude to maintain is
subsequently changed or res tated without an expedite
instruction, the expedite instruction is canceled.Expedite climb/descent normally indicates to the
pilot that the approximate best rate of climb/descent
should be used without requiring an exceptionalchange in aircraft handling characteristics. Normally
controllers will inform pilots of the reason for an
instruction to expedite.
4−4−11. IFR Separation Standards
a.ATC effects separation of aircraft vertically by
assigning different altitudes; longitudinally by
providing an interval expressed in time or distancebetween aircraft on the same, converging, or crossing
courses, and laterally by assigning different flight
paths.
b.Separation will be provided between all aircraft
operating on IFR flight plans except during that partof the flight (outside Class B airspace or a TRSA)
being conducted on a VFR −on−top/VFR conditions
clearance. Under these conditions, ATC may issuetraffic advisories, but it is the sole responsibility of the
pilot to be vigilant so as to see and avoid other aircraft.
c.When radar is employed in the separation of
aircraft at the same altitude, a minimum of 3 miles
separation is provided between aircraft operating
within 40 miles of the radar antenna site, and 5 miles
between aircraft operating beyond 40 miles from the
antenna site. These minima may be increased or
decreased in certain specific situations.
NOTE−
Certain separation standards are increased in the terminal
environment when CENRAP is being utilized.
4−4−12. Speed Adjustments
a.ATC will issue speed adjustments to pilots of
radar−controlled aircraft to achieve or maintain
required or desire spacing.
b.ATC will express all speed adjustments in
terms of knots based on indicated airspeed (IAS) in5 or 10 knot increments except that at or above FL
240 speeds may be expressed in terms of Mach
numbers in 0.01 increments. The use of Mach
AIM 10/12/17
4−4−8 ATC Clearances and Aircraft Separationnumbers is restricted to turbojet aircraft with Mach
meters.
c.Pilots complying with speed adjustments are
expected to maintain a speed within plus or minus
10 knots or 0.02 Mach number of the specified speed.
d.When ATC assigns speed adjustments, it will
be in accordance with the following recommendedminimums:
1.To aircraft operating between FL 280 and
10,000 feet, a speed not less than 250 knots or the
equivalent Mach number.
NOTE−
1.On a standard day the Mach numbers equivalent to
250 knots CAS (subject to minor variations) are:FL 240−0.6
FL 250−0.61
FL 260−0.62
FL 270−0.64
FL 280−0.65
FL 290−0.66.
2.When an operational advantage will be realized, speeds
lower than the recommended minima may be applied.
2.To arriving turbojet aircraft operating below
10,000 feet:
(a)A speed not less than 210 knots, except;
(b)Within 20 flying miles of the airport of
intended landing, a speed not less than 170 knots.
3.To arriving reciprocating engine or turboprop
aircraft within 20 flying miles of the runway
threshold of the airport of intended landing, a speed
not less than 150 knots.
4.To departing aircraft:
(a)Turbojet aircraft, a speed not less than
230 knots.
(b)Reciprocating engine aircraft, a speed not
less than 150 knots.
e.When ATC combines a speed adjustment with
a descent clearance, the sequence of delivery, with the
word “then” between, indicates the expected order of
execution.
EXAMPLE −
1.Descend and maintain (altitude); then, reduce speed to
(speed).
2.Reduce speed to (speed); then, descend and maintain
(altitude).NOTE−
The maximum speeds below 10,000 feet as established in14 CFR Section 91.117 still apply. If there is any doubtconcerning the manner in which such a clearance is to be
executed, request clarification from ATC.
f.If ATC determines (before an approach
clearance is issued) that it is no longer necessary to
apply speed adjustment procedures, they will:
1.Advise the pilot to “resume normal speed.”
Normal speed is used to terminate ATC assigned
speed adjustments on segments where no published
speed restrictions apply. It does not cancel publishedrestrictions on upcoming procedures. This does not
relieve the pilot of those speed restrictions which are
applicable to 14 CFR Section 91.117.
EXAMPLE −
(An aircraft is flying a SID with no published speed
restrictions. ATC issues a speed adjustment and instructsthe aircraft where the adjustment ends): “Maintain two two
zero knots until BALTR then resume normal speed.”
NOTE−
The ATC assigned speed assignment of two two zero knots
would apply until BALTR. The air craft would then resume
a normal operating speed while remaining in compliancewith 14 CFR Section 91.117.
2.Instruct pilots to “comply with speed
restrictions” when the aircraft is joining or resuming
a charted procedure or route with published speed
restrictions.
EXAMPLE −
(ATC vectors an aircraft off of a SID to rejoin the pr ocedure
at a subsequent waypoint. When instructing the aircraft toresume the procedure, ATC also wants the aircraft to
comply with the published procedure speed restrictions):
“Resume the SALTY ONE departure. Comply with speedrestrictions.”
CAUTION −
The phraseology “Descend via/Climb via SID” requires
compliance with all altitude and/or speed restrictionsdepicted on the procedure.
3.Instruct the pilot to “resume published
speed.” Resume published speed is issued to
terminate a speed adjustment where speed restric-
tions are published on a charted procedure.
NOTE−
When instructed to “comply with speed restrictions” or to“resume published speed,” ATC anticipates pilots will
begin adjusting speed the minimum distance necessary
prior to a published speed restriction so as to cross thewaypoint/fix at the published speed. Once at the published
AIM 10/12/17
4−4−9 ATC Clearances and Aircraft Separationspeed, ATC expects pilots will maintain the published
speed until additional adjustment is required to complywith further published or A TC assigned speed restrictions
or as required to ensure compliance with 14 CFR
Section 91.117.
EXAMPLE −
(An aircraft is flying a SID/STAR with published speedrestrictions. ATC issues a speed adjustment and instructsthe aircraft where the adjustment ends): “Maintain two two
zero knots until BALTR then resume published speed.”
NOTE−
The ATC assigned speed assignment of two two zero knotswould apply until BALTR. The aircraft would then complywith the published speed restrictions.
4.Advise the pilot to “delete speed restrictions”
when either ATC assigned or published speedrestrictions on a charted procedure are no longer
required.
EXAMPLE −
(An aircraft is flying a SID with published speedrestrictions designed to prevent aircraft overtake on
departure. ATC determines there is no conflicting traffic
and deletes the speed restriction): “Delete speedrestrictions.”
NOTE−
When deleting published restrictions, ATC must ensureobstacle clearance until aircraft ar e established on a r oute
where no published r estrictions apply. This does not r elieve
the pilot of those speed restrictions which are applicable to
14 CFR Section 91.117.
5.Instruct the pilot to “climb via” or “descend
via.” A climb via or descend via clearance cancels any
previously issued speed restrictions and, onceestablished on the depicted departure or arrival, to
climb or descend, and to meet all published or
assigned altitude and/or speed restrictions.
EXAMPLE −
1.(An aircraft is flying a SID with published speed
restrictions. ATC has issued a speed r estriction of 250 knots
for spacing. ATC determines that spacing between air craft
is adequate and desires the aircraft to comply with
published restrictions): “United 436, Climb via SID.”
2.(An aircraft is established on a STAR. ATC must slow an
aircraft for the purposes of spacing and assigns it a speed
of 280 knots. When spacing is adequate, ATC deletes thespeed restriction and desires that the aircraft comply withall published restrictions on the STAR): “Gulfstream two
three papa echo, descend via the TYLER One arrival.”
NOTE−
1.In example 1, when ATC issues a “Climb via SID”
clearance, it deletes any previously issued speed and/oraltitude restrictions. The pilot should then vertically
navigate to comply with all speed and/or altituderestrictions published on the SID.
2.In example 2, when ATC issues a “Descend via <STAR
name> arrival,” ATC has canceled any previously issued
speed and/or altitude restrictions. The pilot should
vertically navigate to comply with all speed and/or altitude
restrictions published on the STAR.
CAUTION −
When descending on a STAR, pilots should not speed upexcessively beyond the pr eviously issued speed. Otherwise,
adequate spacing between aircraft descending on the STAR
that was established by ATC with the previous restrictionmay be lost.
g.Approach clearances supersede any prior speed
adjustment assignments, and pilots are expected to
make their own speed adjustments as necessary to
complete the approach. However, under certaincircumstances, it may be necessary for ATC to issue
further speed adjustments after approach clearance is
issued to maintain separation between successivearrivals. Under such circumstances, previously
issued speed adjustments will be restated if that speed
is to be maintained or additional speed adjustmentsare requested. Speed adjustments should not be
assigned inside the final approach fix on final or a
point 5 miles from the runway, whichever is closer to
the runway.
h.The pilots retain the prerogative of rejecting the
application of speed adjustment by ATC if the
minimum safe airspeed for any particular operation is
greater than the speed adjustment.
NOTE−
In such cases, pilots are expected to advise ATC of thespeed that will be used.
i.Pilots are reminded that they are responsible for
rejecting the application of speed adjustment by ATC
if, in their opinion, it will cause them to exceed the
maximum indicated airspeed prescribed by 14 CFR
Section 91.117(a), (c) and (d). IN SUCH CASES,
THE PILOT IS EXPECTED TO SO INFORM ATC.
Pilots operating at or above 10,000 feet MSL who are
issued speed adjustments which exceed 250 knotsIAS and are subsequently cleared below 10,000 feet
MSL are expected to comply with 14 CFR
Section 91.117(a).
j.Speed restrictions of 250 knots do not apply to
U.S. registered aircraft operating beyond 12 nautical
miles from the coastline within the U.S. Flight
AIM 10/12/17
4−4−10 ATC Clearances and Aircraft SeparationInformation Region, in Class E airspace below
10,000 feet MSL. However, in airspace underlying a
Class B airspace area designated for an airport, or in
a VFR corridor designated through such as a Class B
airspace area, pilots are expected to comply with the200 knot speed limit specified in 14 CFR
Section 91.117(c).
k.For operations in a Class C and Class D surface
area, ATC is authorized to request or approve a speed
greater than the maximum indicated airspeeds
prescribed for operation within that airspace (14 CFR
Section 91.117(b)).
NOTE−
Pilots are expected to comply with the maximum speed of200 knots when operating beneath Class B airspace or ina Class B VFR corridor (14 CFR Section 91.117(c)and (d)).
l.When in communications with the ARTCC or
approach control facility, pilots should, as a good
operating practice, state any ATC assigned speed
restriction on initial radio contact associated with an
ATC communications frequency change.
4−4−13. Runway Separation
Tower controllers establish the sequence of arriving
and departing aircraft by requiring them to adjust
flight or ground operation as necessary to achieveproper spacing. They may “HOLD” an aircraft short
of the runway to achieve spacing between it and an
arriving aircraft; the controller may instruct a pilot to
“EXTEND DOWNWIND” in order to establish
spacing from an arriving or departing aircraft. At
times a clearance may include the word “IMMEDI-ATE.” For example: “CLEARED FOR
IMMEDIATE TAKEOFF.” In such cases “IMMEDI-
ATE” is used for purposes of air traffic separation. It
is up to the pilot to refuse the clearance if, in the pilot’s
opinion, compliance would adversely affect the
operation.
REFERENCE −
AIM, Paragraph 4 −3−15 , Gate Holding due to Departure Delays
4−4−14. Visual Separation
a.Visual separation is a means employed by ATC
to separate aircraft in terminal areas and en route
airspace in the NAS. There are two methods
employed to effect this separation:1.The tower controller sees the aircraft
involved and issues instructions, as necessary, to
ensure that the aircraft avoid each other.
2.A pilot sees the other aircraft involved and
upon instructions from the controller providesseparation by maneuvering the aircraft to avoid it.
When pilots accept responsibility to maintain visual
separation, they must maintain constant visualsurveillance and not pass the other aircraft until it is
no longer a factor.
NOTE−
Traffic is no longer a factor when during approach phase
the other aircraft is in the landing phase of flight or
executes a missed approach; and during departure oren route, when the other aircraft turns away or is on adiverging course.
b.A pilot’s acceptance of instructions to follow
another aircraft or provide visual separation from it is
an acknowledgment that the pilot will maneuver the
aircraft as necessary to avoid the other aircraft or tomaintain in −trail separation. In operations conducted
behind heavy aircraft, or a small aircraft behind a
B757 or other large aircraft, it is also anacknowledgment that the pilot accepts the responsi-
bility for wake turbulence separation. Visual
separation is prohibited behind super aircraft.
NOTE−
When a pilot has been told to follow another aircraft or to
provide visual separation from it, the pilot should pr omptly
notify the controller if visual contact with the other air craft
is lost or cannot be maintained or if the pilot cannot accept
the responsibility for the separation for any reason.
c.Scanning the sky for other aircraft is a key factor
in collision avoidance. Pilots and copilots (or the right
seat passenger) should continuously scan to cover all
areas of the sky visible from the cockpit. Pilots must
develop an effective scanning technique which
maximizes one’s visual capabilities. Spotting apotential collision threat increases directly as more
time is spent looking outside the aircraft. One must
use timesharing techniques to effectively scan thesurrounding airspace while monitoring instruments
as well.
d.Since the eye can focus only on a narrow
viewing area, effective scanning is accomplished
with a series of short, regularly spaced eye
movements that bring successive areas of the sky into
the central visual field. Each movement should not
exceed ten degrees, and each area should be observed
for at least one second to enable collision detection.
AIM 10/12/17
4−4−11 ATC Clearances and Aircraft SeparationAlthough many pilots seem to prefer the method of
horizontal back −and−forth scanning every pilot
should develop a scanning pattern that is not only
comfortable but assures optimum effectiveness.
Pilots should remember, however, that they have aregulatory responsibility (14 CFR Section 91.113(a))
to see and avoid other aircraft when weather
conditions permit.
4−4−15. Use of Visual Clearing Procedures
a. Before T akeoff. Prior to taxiing onto a runway
or landing area in preparation for takeoff, pilotsshould scan the approach areas for possible landing
traffic and execute the appropriate clearing maneu-
vers to provide them a clear view of the approachareas.
b. Climbs and Descents. During climbs and
descents in flight conditions which permit visual
detection of other traf fic, pilots should execute gentle
banks, left and right at a frequency which permitscontinuous visual scanning of the airspace about
them.
c. Straight and Level. Sustained periods of
straight and level flight in conditions which permit
visual detection of other traffic should be broken atintervals with appropriate clearing procedures to
provide effective visual scanning.
d. Traffic Pattern. Entries into traffic patterns
while descending create specific collision hazards
and should be avoided.
e. Traffic at VOR Sites. All operators should
emphasize the need for sustained vigilance in thevicinity of VORs and airway intersections due to the
convergence of traffic.
f. Training Operations. Operators of pilot train-
ing programs are urged to adopt the following
practices:
1.Pilots undergoing flight instruction at all
levels should be requested to verbalize clearingprocedures (call out “clear” left, right, above, or
below) to instill and sustain the habit of vigilance
during maneuvering.
2. High−wing airplane. Momentarily raise the
wing in the direction of the intended turn and look.3. Low−wing airplane. Momentarily lower
the wing in the direction of the intended turn and look.
4.Appropriate clearing procedures should
precede the execution of all turns includingchandelles, lazy eights, stalls, slow flight, climbs,
straight and level, spins, and other combination
maneuvers.
4−4−16. Traffic Alert and Collision
Avoidance System (TCAS I & II)
a. TCAS I provides proximity warning only, to
assist the pilot in the visual acquisition of intruderaircraft. No recommended avoidance maneuvers are
provided nor authorized as a direct result of a TCAS I
warning. It is intended for use by smaller commuteraircraft holding 10 to 30 passenger seats, and general
aviation aircraft.
b. TCAS II provides traffic advisories (TAs) and
resolution advisories (RAs). Resolution advisories
provide recommended maneuvers in a verticaldirection (climb or descend only) to avoid conflicting
traffic. Airline aircraft, and larger commuter and
business aircraft holding 31 passenger seats or more,
use TCAS II equipment.
1.Each pilot who deviates from an ATC
clearance in response to a TCAS II RA must notify
ATC of that deviation as soon as practicable andexpeditiously return to the current ATC clearance
when the traffic conflict is resolved.
2.Deviations from rules, policies, or clearances
should be kept to the minimum necessary to satisfy a
TCAS II RA.
3.The serving IFR air traffic facility is not
responsible to provide approved standard IFRseparation to an aircraft after a TCAS II RA maneuver
until one of the following conditions exists:
(a)The aircraft has returned to its assigned
altitude and course.
(b)Alternate ATC instructions have been
issued.
c.TCAS does not al ter or diminish the pilot’s basic
authority and responsibility to ensure safe flight.
Since TCAS does not respond to aircraft which arenot transponder equipped or aircraft with a
transponder failure, TCAS alone does not ensure safe
separation in every case.
AIM 10/12/17
4−4−12 ATC Clearances and Aircraft Separationd.At this time, no air traffic service nor handling
is predicated on the availability of TCAS equipment
in the aircraft.
4−4−17. Traffic Information Service (TIS)
a.TIS provides proximity warning only, to assist
the pilot in the visual acquisition of intruder aircraft.
No recommended avoidance maneuvers are providednor authorized as a direct result of a TIS intruder
display or TIS alert. It is intended for use by aircraft
in which TCAS is not required.
b.TIS does not alter or diminish the pilot’s basic
authority and responsibility to ensure safe flight.Since TIS does not respond to aircraft which are not
transponder equipped, aircraft with a transponder
failure, or aircraft out of radar coverage, TIS alone
does not ensure safe separation in every case.
c.At this time, no air traffic service nor handling
is predicated on the availability of TIS equipment in
the aircraft.
d.Presently, no air traffic services or handling is
predicated on the availability of an ADS −B cockpit
display. A “traffic −in−sight” reply to ATC must be
based on seeing an aircraft out −the−window, NOT
on
the cockpit display.
AIM 10/12/17
4−5−1 Surveillance SystemsSection 5. Surveillance Systems
4−5−1. Radar
a. Capabilities
1.Radar is a method whereby radio waves are
transmitted into the air and are then received when
they have been reflected by an object in the path of the
beam. Range is determined by measuring the time it
takes (at the speed of light) for the radio wave to go
out to the object and then return to the receivingantenna. The direction of a detected object from a
radar site is determined by the position of the rotating
antenna when the reflected portion of the radio wave
is received.
2.More reliable maintenance and improved
equipment have reduced radar system failures to a
negligible factor. Most facilities actually have some
components duplicated, one operating and anotherwhich immediately takes over when a malfunction
occurs to the primary component.
b. Limitations
1.It is very important for the aviation
community to recognize the fact that there are
limitations to radar service and that ATC controllers
may not always be able to issue traffic advisoriesconcerning aircraft which are not under ATC control
and cannot be seen on radar. (See FIG 4−5−1.)
FIG 4−5−1
Limitations to Radar Service
Precipitation Attenuation
The nearby target absorbs and scatters so much of the out-going and returning
energy that the radar does not detect the distant target.AREA BLACKED OUT
BY ATTENUATION
NOT OBSERVED
OBSERVED
ECHO(a)The characteristics of radio waves are
such that they normally travel in a continuous straight
line unless they are:
(1)“Bent” by abnormal atmospheric phe-
nomena such as temperature inversions;
(2)Reflected or attenuated by dense
objects such as heavy clouds, precipitation, groundobstacles, mountains, etc.; or
(3)Screened by high terrain features.
(b)The bending of radar pulses, often called
anomalous propagation or ducting, may cause manyextraneous blips to appear on the radar operator’s
display if the beam has been bent toward the ground
or may decrease the detection range if the wave isbent upward. It is difficult to solve the effects of
anomalous propagation, but using beacon radar and
electronically eliminating stationary and slow
moving targets by a method called moving target
indicator (MTI) usually negate the problem.
(c)Radar energy that strikes dense objects
will be reflected and displayed on the operator’s
scope thereby blocking out aircraft at the same range
and greatly weakening or completely eliminating the
display of targets at a greater range. Again, radarbeacon and MTI are very effectively used to combat
ground clutter and weather phenomena, and a method
of circularly polarizing the radar beam will eliminatesome weather returns. A negative characteristic of
MTI is that an aircraft flying a speed that coincides
with the canceling signal of the MTI (tangential or“blind” speed) may not be displayed to the radar
controller.
(d)Relatively low altitude aircraft will not be
seen if they are screened by mountains or are below
the radar beam due to earth curvature. The onlysolution to screening is the installation of strategi-
cally placed multiple radars which has been done in
some areas.
(e)There are several other factors which
affect radar control. The amount of reflective surface
of an aircraft will determine the size of the radar
return. Therefore, a small light airplane or a sleek jet
fighter will be more difficult to see on radar than alarge commercial jet or military bomber. Here again,
the use of radar beacon is invaluable if the aircraft is
AIM 10/12/17
4−5−2 Surveillance Systemsequipped with an airborne transponder. All AR TCCs’
radars in the conterminous U.S. and many airport
surveillance radars have the capability to interrogate
Mode C and display altitude information to the
controller from appropriately equipped aircraft.However, there are a number of airport surveillance
radars that don’t have Mode C display capability and;
therefore, altitude information must be obtained from
the pilot.
(f)At some locations within the ATC en route
environment, secondary −radar−only (no primary
radar) gap filler radar systems are used to give lower
altitude radar coverage between two larger radar
systems, each of which provides both primary andsecondary radar coverage. In those geographical
areas served by secondary −radar only, aircraft
without transponders cannot be provided with radar
service. Additionally, transponder equipped aircraft
cannot be provided with radar advisories concerningprimary targets and weather.
REFERENCE −
Pilot/Controller Glossary Term − Radar.
(g)The controller’s ability to advise a pilot
flying on instruments or in visual conditions of the
aircraft’s proximity to another aircraft will be limited
if the unknown aircraft is not observed on radar, if noflight plan information is available, or if the volume
of traffic and workload prevent issuing traffic
information. The controller’s first priority is given to
establishing vertical, lateral, or longitudinal separa-
tion between aircraft flying IFR under the control of
ATC.
c.FAA radar units operate continuously at the
locations shown in the Chart Supplement U.S., and
their services are available to all pilots, both civil and
military. Contact the associated FAA control tower or
ARTCC on any frequency guarded for initial
instructions, or in an emer gency, any FAA facility for
information on the nearest radar service.
4−5−2. Air Traffic Control Radar Beacon
System (ATCRBS)
a.The ATCRBS, sometimes referred to as
secondary surveillance radar, consists of three main
components:
1. Interrogator. Primary radar relies on a
signal being transmitted from the radar antenna site
and for this signal to be reflected or “bounced back”from an object (such as an aircraft). This reflected
signal is then displayed as a “target” on the
controller’s radarscope. In the ATCRBS, the
Interrogator, a ground based radar beacon transmit-
ter−receiver, scans in synchronism with the primary
radar and transmits discrete radio signals which
repetitiously request all transponders, on the mode
being used, to reply. The replies received are thenmixed with the primary returns and both are
displayed on the same radarscope.
2. Transponder. This airborne radar beacon
transmitter −receiver automatically receives the sig-
nals from the interrogator and selectively replies with
a specific pulse group (code) only to thoseinterrogations being received on the mode to which
it is set. These replies are independent of, and much
stronger than a primary radar return.
3. Radarscope. The radarscope used by the
controller displays returns from both the primary
radar system and the A TCRBS. These returns, called
targets, are what the controller refers to in the control
and separation of traffic.
b.The job of identifying and maintaining
identification of primary radar targets is a long and
tedious task for the controller. Some of the
advantages of ATCRBS over primary radar are:
1.Reinforcement of radar targets.
2.Rapid target identification.
3.Unique display of selected codes.
c.A part of the ATCRBS ground equipment is the
decoder. This equipment enables a controller to
assign discrete transponder codes to each aircraftunder his/her control. Normally only one code will be
assigned for the entire flight. Assignments are made
by the ARTCC computer on the basis of the NationalBeacon Code Allocation Plan. The equipment is also
designed to receive Mode C altitude information
from the aircraft.
NOTE−
Refer to figures with explanatory legends for an illustration
of the target symbology depicted on radar scopes in theNAS Stage A (en route), the ARTS III (terminal) Systems,and other nonautomated (broadband) radar systems. (SeeFIG 4−5−2 and FIG 4−5−3.)
d.It should be emphasized that aircraft transpond-
ers greatly improve the effectiveness of radar
systems.
REFERENCE −
AIM, Paragraph 4 −1−20 , Transponder Operation
AIM 10/12/17
4−5−3 Surveillance SystemsFIG 4−5−2
ARTS III Radar Scope With Alphanumeric Data
NOTE−
A number of radar terminals do not have ARTS equipment. Those facilities and certain ARTCCs outside the contiguous U.S.
would have radar displays similar to the lower right hand subset. ARTS facilities and NAS Stage A ARTCCs, when operating
in the nonautomation mode, would also have similar displays and certain services based on automation may not beavailable.
AIM 10/12/17
4−5−4 Surveillance SystemsEXAMPLE −
1.Areas of precipitation (can be reduced by CP)
2.Arrival/departure tabular list
3.Trackball (control) position symbol (A)
4.Airway (lines are sometimes deleted in part)
5.Radar limit line for control
6.Obstruction (video map)
7.Primary radar returns of obstacles or terrain (can be
removed by MTI)
8.Satellite airports
9.Runway centerlines (marks and spaces indicate
miles)
10.Primary airport with parallel runways
11.Approach gates
12.Tracked target (primary and beacon target)
13.Control position symbol
14. Untracked target select code (monitored) with
Mode C readout of 5,000’
15.Untracked target without Mode C
16.Primary target
17.Beacon tar get only (secondary radar) (transponder)
18.Primary and beacon target
19.Leader line
20.Altitude Mode C readout is 6,000’
(Note: readouts may not be displayed because of
nonreceipt of beacon information, garbled beacon
signals, and flight plan data which is displayedalternately with the altitude readout)
21.Ground speed readout is 240 knots
(Note: readouts may not be displayed because of a loss
of beacon signal, a controller alert that a pilot was
squawking emergency, radio failure, etc.)
22.Aircraft ID
23.Asterisk indicates a controller entry in Mode C
block. In this case 5,000’ is entered and “05” would
alternate with Mode C readout.
24.Indicates heavy25.“Low ALT” flashes to indicate when an aircraft’ s
predicted descent places the aircraft in an unsafe
proximity to terrain.
(Note: this feature does not function if the aircraft is not
squawking Mode C. When a helicopter or aircraft is
known to be operating below the lower safe limit, the
“low ALT” can be changed to “inhibit” and flashing
ceases.)
26.NAVAIDs
27.Airways
28.Primary target only
29. Nonmonitored. No Mode C (an asterisk would
indicate nonmonitored with Mode C)
30.Beacon target only (secondary radar based on
aircraft transponder)
31.Tracked target (primary and beacon target) control
position A
32.Aircraft is squawking emergency Code 7700 and is
nonmonitored, untracked, Mode C
Controller assigned runway 36 right alternates with
Mode C readout
(Note: a three letter identifier could also indicate the
arrival is at specific airport)
34.Ident flashes
35.Identing target blossoms
36.Untracked target identing on a selected code
37. Range marks (10 and 15 miles) (can be
changed/offset)
38.Aircraft controlled by center
39.Targets in suspend status
40.Coast/suspend list (air craft holding, temporary loss
of beacon/target, etc.)
41.Radio failure (emergency information)
42.Select beacon codes (being monitored)
43.General information (ATIS, runway, approach in
use)
44.Altimeter setting
45.Time
46.System data area
AIM 10/12/17
4−5−5 Surveillance SystemsFIG 4−5−3
NAS Stage A Controllers View Plan Display
This figure illustrates the controller’s radar scope (PVD) when operating in the full automation (RDP) mode, which is
normally 20 hours per day.
(When not in automation mode, the display is similar to the broadband mode shown in the ARTS III radar scope figure.
Certain ARTCCs outside the contiguous U.S. also operate in “broadband” mode.)
2526X
XXXXXXXX
#
XXXAAL373
280C191H-33AAL373280C191H-33
VIG123
310N095VIG123310N095
NWA258170 143NWA258170 143
AAL353
2734AAL35370 231
R15909170CR15909170C
21032902103N1467F
140 + 143460N1467F140 + 143460UAL33100A296UAL33100A296
7700EMRG7700EMRG7600RDOF7600RDOF12001200
++++ UAL712
310N
228CSTUAL712
310N
228CST12223
H
H
HHHHHHHH
H
H
HRADAR SERVICES AND PROCEDURES
AIM 10/12/17
4−5−6 Surveillance SystemsEXAMPLE −
Target symbols:
1. Uncorrelated primary radar target [/C0100] [+]
2. Correlated primary radar target [/C0002]
/C0058See note below.
3. Uncorrelated beacon target [ / ]
4. Correlated beacon target [ \ ]
5. Identing beacon target [/C0053]
/C0058Note: in Number 2 correlated means the association of
radar data with the computer projected track of anidentified aircraft.
Position symbols:
6. Free track (no flight plan tracking) [/C0110]
7. Flat track (flight plan tracking) [/C0224]
8. Coast (beacon target lost) [#]
9. Present position hold [ /C0002
]
Data block information:
10. Aircraft ident
/C0058See note below.
11. Assigned altitude FL 280, Mode C altitude same or
within /C0006 200’ of assigned altitude.
/C0058See note below.
12. Computer ID #191, handoff is to sector 33
(0−33 would mean handoff accepted)
/C0058See note below.
13. Assigned altitude 17,000’, aircraft is climbing,
Mode C readout was 14,300 when last beacon interroga-tion was received.
14. Leader line connecting target symbol and data block
15. Track velocity and direction vector line (projected
ahead of target)16. Assigned altitude 7,000, aircraft is descending, last
Mode C re adout (or last reported altitude) was 100’ above
FL 230
17. Transponder code shows in full data block only when
different than assigned code
18. Aircraft is 300’ above assigned altitude
19. Reported altitude (no Mode C readout) same as
assigned. (An “n” would indicate no reported altitude.)
20. Transponder set on emergency Code 7700 (EMRG
flashes to attract attention)
21. Transponder Code 1200 (VFR) with no Mode C22. Code 1200 (VFR) with Mode C and last altitude
readout
23. Transponder set on radio failure Code 7600 (RDOF
flashes)
24. Computer ID #228, CST indicates target is in coast
status
25. Assigned altitude FL 290, transponder code (these two
items constitute a “limited data block”)
/C0058Note: numbers 10, 11, and 12 constitute a “full data
block”
Other symbols:
26. Navigational aid
27. Airway or jet route
28. Outline of weather returns based on primary radar.
“H” represents areas of high density precipitation whichmight be thunderstorms. Radial lines indicated lowerdensity precipitation.
29. Obstruction
30. Airports
Major:
Small:
AIM 10/12/17
4−5−7 Surveillance Systems4−5−3. Surveillance Radar
a.Surveillance radars are divided into two general
categories: Airport Surveillance Radar (ASR) andAir Route Surveillance Radar (ARSR).
1.ASR is designed to provide relatively
short−range coverage in the general vicinity of an
airport and to serve as an expeditious means ofhandling termina l area traffic through observation of
precise aircraft locations on a radarscope. The ASR
can also be used as an instrument approach aid.
2.ARSR is a long−range radar system designed
primarily to provide a display of aircraft locations
over large areas.
3.Center Radar Automated Radar Terminal
Systems (ARTS) Processing (CENRAP) was devel-oped to provide an alternative to a nonradar
environment at terminal facilities should an ASR fail
or malfunction. CENRAP sends aircraft radar beacontarget information to the ASR terminal facility
equipped with ARTS. Procedures used for the
separation of aircraft may increase under certainconditions when a facility is utilizing CENRAP
because radar target information updates at a slower
rate than the normal ASR radar. Radar services forVFR aircraft are also limited during CENRAP
operations because of the additional workload
required to provide services to IFR aircraft.
b.Surveillance radars scan through 360 degrees of
azimuth and present target information on a radar
display located in a tower or center. This information
is used independently or in conjunction with othernavigational aids in the control of air traffic.
4−5−4. Precision Approach Radar (PAR)
a.PAR is designed for use as a landing aid rather
than an aid for sequencing and spacing aircraft. PAR
equipment may be used as a primary landing aid (See
Chapter 5, Air Traffic Procedures, for additional
information), or it may be used to monitor other types
of approaches. It is designed to display range,
azimuth, and elevation information.
b.Two antennas are used in the PAR array, one
scanning a vertical plane, and the other scanninghorizontally. Since the range is limited to 10 miles,
azimuth to 20 degrees, and elevation to 7 degrees,
only the final approach area is covered. Each scope is
divided into two parts. The upper half presents
altitude and distance information, and the lower halfpresents azimuth and distance.
4−5−5. Airport Surface Detection
Equipment (ASDE −X)/Airport Surface
Surveillance Capability (ASSC)
a.ASDE−X/ASSC is a multi −sensor surface
surveillance system the FAA is acquiring for airports
in the United States. This system provides highresolution, short −range, clutter free surveillance
information about aircraft and vehicles, both moving
and fixed, located on or near the surface of theairport’s runways and taxiways under all weather and
visibility conditions. The system consists of:
1. A Primary Radar System. ASDE−
X/
ASSC system coverage includes the airport surface
and the airspace up to 200 feet above the surface.
Typically located on the control tower or otherstrategic location on the airport, the Primary Radar
antenna is able to detect and display aircraft that are
not equipped with or have malfunctioning transpond-
ers.
2. Interfaces. ASDE−X/ASSC contains an
automation interface for flight identification via allautomation platforms and interfaces with the
terminal radar for position information.
3. Automation. A Multi−sensor Data Proces-
sor (MSDP) combines all sensor reports into a single
target which is displayed to the air traffic controller.
4. Air Traffic Control Tower Display. A high
resolution, color monitor in the control tower cab
provides controllers with a seamless picture of airport
operations on the airport surface.
b.The combination of data collected from the
multiple sensors ensures that the most accurate
information about aircraft location is received in thetower, thereby increasing surface safety and
efficiency.
AIM 10/12/17
4−5−8 Surveillance Systemsc.The following facilities are operational with
ASDE−X:
TBL 4−5−1
BWI Baltimore Washington International
BOS Boston Logan International
BDL Bradley International
MDW Chicago Midway
ORD Chicago O’Hare International
CLT Charlotte Douglas International
DFW Dallas/Fort Worth International
DEN Denver International
DTW Detroit Metro Wayne County
FLL Fort Lauderdale/Hollywood Intl
MKE General Mitchell International
IAH George Bush International
ATL Hartsfield −Jackson Atlanta Intl
HNL Honolulu International
JFK John F. Kennedy International
SNA John Wayne −Orange County
LGA LaGuardia
STL Lambert St. Louis International
LAS Las Vegas McCarran International
LAX Los Angeles International
SDF Louisville International
MEM Memphis International
MIA Miami International
MSP Minneapolis St. Paul International
EWR Newark International
MCO Orlando International
PHL Philadelphia International
PHX Phoenix Sky Harbor International
DCA Ronald Reagan Washington National
SAN San Diego International
SLC Salt Lake City International
SEA Seattle−Tacoma International
PVD Theodore Francis Green State
IAD Washington Dulles International
HOU William P. Hobby Internationald.The following facilities have been projected to
receive ASSC:
TBL 4−5−2
SFO San Francisco International
CLE Cleveland −Hopkins International
MCI Kansas City International
CVG Cincinnati/Northern Kentucky Intl
PDX Portland International
MSY Louis Armstrong New Orleans Intl
PIT Pittsburgh International
ANC Ted Stevens Anchorage International
ADW Joint Base Andrews AFB
4−5−6. Traffic Information Service (TIS)
a. Introduction.
The Traffic Information Service (TIS) provides
information to the cockpit via data link, that is similar
to VFR radar traffic advisories normally received
over voice radio. Among the first FAA−provided data
services, TIS is intended to improve the safety and
efficiency of “see and avoid” flight through an
automatic display that informs the pilot of nearbytraffic and potential conflict situations. This traffic
display is intended to assist the pilot in visual
acquisition of these aircraft. TIS employs anenhanced capability of the terminal Mode S radar
system, which contains the surveillance data, as well
as the data link required to “uplink” this informationto suitably −equipped aircraft (known as a TIS
“client”). TIS provides estimated position, altitude,
altitude trend, and ground track information for up to
8 intruder aircraft within 7 NM horizontally,
+3,500 and −3,000 feet vertically of the client aircraft
(see FIG 4−5−4, TIS Proximity Coverage V olume).
The range of a target reported at a distance greater
than 7 NM only indicates that this target will be athreat within 34 seconds and does not display an
precise distance. TIS will alert the pilot to aircraft
(under surveillance of the Mode S radar) that areestimated to be within 34 seconds of potential
collision, regardless of distance of altitude. TIS
surveillance data is derived from the same radar used
by ATC; this data is uplinked to the client aircraft on
each radar scan (nominally every 5 seconds).
AIM 10/12/17
4−5−9 Surveillance Systemsb. Requirements.
1.In order to use TIS, the client and any intruder
aircraft must be equipped with the appropriate
cockpit equipment and fly within the radar coverageof a Mode S radar capable of providing TIS.Typically, this will be within 55 NM of the sites
depicted in FIG 4−5−5, Terminal Mode S Radar Sites.
ATC communication is not a requirement to receive
TIS, although it may be required by the particular
airspace or flight operations in which TIS is beingused.
FIG 4−5−4
TIS Proximity Coverage Volume
FIG 4−5−5
Terminal Mode S Radar Sites
AIM 10/12/17
4−5−10 Surveillance SystemsFIG 4−5−6
Traffic Information Service (TIS)
Avionics Block Diagram
AIM 10/12/17
4−5−11 Surveillance Systems2.The cockpit equipment functionality required
by a TIS client aircraft to receive the service consists
of the following (refer to FIG 4−5−6):
(a)Mode S data link transponder with
altitude encoder.
(b)Data link applications processor with TIS
software installed.
(c)Control−display unit.
(d)Optional equipment includes a digital
heading source to correct display errors caused by
“crab angle” and turning maneuvers.
NOTE−
Some of the above functions will likely be combined into
single pieces of avionics, such as (a) and (b).
3.To be visible to the TIS client, the intruder
aircraft must, at a minimum, have an operating
transponder (Mode A, C or S). All altitudeinformation provided by TIS from intruder aircraft is
derived from Mode C reports, if appropriately
equipped.
4.TIS will initially be provided by the terminal
Mode S systems that are paired with ASR −9 digital
primary radars. These systems are in locations with
the greatest traffic densities, thus will provide the
greatest initial benefit. The remaining terminalMode S sensors, which are paired with ASR −7 or
ASR−8 analog primary radars, will provide TIS
pending modification or relocation of these sites. See
FIG 4−5−5, Terminal Mode S Radar Sites, for site
locations. There is no mechanism in place, such as
NOTAMs, to provide status update on individualradar sites since TIS is a nonessential, supplemental
information service.
The FAA also operates en route Mode S radars (not
illustrated) that rotate once every 12 seconds. These
sites will require additional development of TISbefore any possible implementation. There are no
plans to implement TIS in the en route Mode S radars
at the present time.
c. Capabilities.
1.TIS provides ground −based surveillance
information over the Mode S data link to properly
equipped client aircraft to aid in visual acquisition of
proximate air traf fic. The actual avionics capability of
each installation will vary and the supplemental
handbook material must be consulted prior to usingTIS. A maximum of eight (8) intruder aircraft may be
displayed; if more than eight aircraft match intruder
parameters, the eight “most significant” intruders are
uplinked. These “most significant” intruders are
usually the ones in closest proximity and/or thegreatest threat to the TIS client.
2.TIS, through the Mode S ground sensor,
provides the following data on each intruder aircraft:
(a)Relative bearing information in 6 −degree
increments.
(b)Relative range information in 1/8 NM to
1 NM increments (depending on range).
(c)Relative altitude in 100 −foot increments
(within 1,000 feet) or 500 −foot increments (from
1,000−3,500 feet) if the intruder aircraft has operating
altitude reporting capability.
(d)Estimated intruder ground track in
45−degree increments.
(e)Altitude trend data (level within 500 fpm
or climbing/descending >500 fpm) if the intruder
aircraft has operating altitude reporting capability.
(f)Intruder priority as either an “traffic
advisory” or “proximate” intruder.
3.When flying from surveillance coverage of
one Mode S sensor to another, the transfer of TIS is
an automatic function of the avionics system andrequires no action from the pilot.
There are a variety of status messages that are
provided by either the airborne system or groundequipment to alert the pilot of high priority intruders
and data link system status. These messages include
the following:
(a) Alert. Identifies a potential collision
hazard within 34 seconds. This alert may be visual
and/or audible, such as a flashing display symbol or
a headset tone. A target is a threat if the time to the
closest approach in vertical and horizontal coordi-nates is less than 30 seconds and
the closest approach
is expected to be within 500 feet vertically and
0.5 nautical miles laterally.
(b) TIS Traffic. TIS traffic data is displayed.
(c) Coasting. The TIS display is more than
6 seconds old. This indicates a missing uplink fromthe ground system. When the TIS display information
is more than 12 seconds old, the “No Traffic” status
will be indicated.
AIM 10/12/17
4−5−12 Surveillance Systems(d) No Traffic. No intruders meet proximate
or alert criteria. This condition may exist when the
TIS system is fully functional or may indicate
“coasting” between 12 and 59 seconds old (see (c)
above).
(e) TIS Unavailable. The pilot has re-
quested TIS, but no ground system is available. This
condition will also be displayed when TIS uplinks are
missing for 60 seconds or more.
(f) TIS Disabled. The pilot has not requested
TIS or has disconnected from TIS.
(g) Good −bye. The client aircraft has flown
outside of TIS coverage.
NOTE−
Depending on the avionics manufacturer implementation,
it is possible that some of these messages will not be dir ectly
available to the pilot.
5.Depending on avionics system design, TIS
may be presented to the pilot in a variety of different
displays, including text and/or graphics. V oice
annunciation may also be used, either alone or incombination with a visual display. FIG 4 −5−6,
Traffic Information Service (TIS), Avionics Block
Diagram, shows an example of a TIS display using
symbology similar to the Traffic Alert and Collision
Avoidance System (TCAS) installed on most
passenger air carrier/commuter aircraft in the U.S.The small symbol in the center represents the client
aircraft and the display is oriented “track up,” with the
12 o’clock position at the top. The range ringsindicate 2 and 5 NM. Each intruder is depicted by a
symbol positioned at the approximate relative
bearing and range from the client aircraft. The
circular symbol near the center indicates an “alert”
intruder and the diamond symbols indicate “proxi-mate” intruders.
6.The inset in the lower right corner of
FIG 4−5−6, Traffic Information Service (TIS),
Avionics Block Diagram,
shows a possible TIS data
block display. The following information is con-
tained in this data block:
(a)The intruder, located approximately
four o’clock, three miles, is a “proximate” aircraftand currently not a collision threat to the client
aircraft. This is indicated by the diamond symbol
used in this example.(b)The intruder ground track diverges to the
right of the client aircraft, indicated by the small
arrow.
(c)The intruder altitude is 700 feet less than
or below the client aircraft, indicated by the “ −07”
located under the symbol.
(d)The intruder is descending >500 fpm,
indicated by the downward arrow next to the “ −07”
relative altitude information. The absence of thisarrow when an altitude tag is present indicates level
flight or a climb/descent rate less than 500 fpm.
NOTE−
If the intruder did not have an operating altitude encoder
(Mode C), the altitude and altitude trend “tags” would
have been omitted.
d. Limitations.
1.TIS is NOT intended to be used as a collision
avoidance system and does not relieve the pilot
responsibility to “see and avoid” other aircraft (see
paragraph 5 −5−8, See and Avoid). TIS must not be for
avoidance maneuvers during IMC or other times
when there is no visual contact with the intruder
aircraft. TIS is intended only to assist in visualacquisition of other aircraft in VMC. No recom-
mended avoidance maneuvers are provided for,
nor authorized, as a direct result of a TIS intruder
display or TIS alert.
2.While TIS is a useful aid to visual traffic
avoidance, it has some system limitations that mustbe fully understood to ensure proper use. Many of
these limitations are inherent in secondary radar
surveillance. In other words, the informationprovided by TIS will be no better than that provided
to ATC. Other limitations and anomalies are
associated with the TIS predictive algorithm.
(a) Intruder Display Limitations. TIS will
only display aircraft with operating transponders
installed. TIS relies on surveillance of the Mode Sradar, which is a “secondary surveillance” radar
similar to the ATCRBS described in para-
graph 4−5−2.
(b) TIS Client Altitude Reporting Require-
ment. Altitude reporting is required by the TIS client
aircraft in order to receive TIS. If the altitude encoder
is inoperative or disabled, TIS will be unavailable, asTIS requests will not be honored by the ground
system. As such, TIS requires altitude reporting to
determine the Proximity Coverage V olume as
AIM 10/12/17
4−5−13 Surveillance Systemsindicated in FIG 4−5−4. TIS users must be alert to
altitude encoder malfunctions, as TIS has no
mechanism to determine if client altitude reporting is
correct. A failure of this nature will cause erroneous
and possibly unpredictable TIS operation. If thismalfunction is suspected, confirmation of altitude
reporting with ATC is suggested.
(c) Intruder Altitude Reporting. Intruders
without altitude reporting capability will be dis-
played without the accompanying altitude tag.Additionally, nonaltitude reporting intruders are
assumed to be at the same altitude as the TIS client for
alert computations. This helps to ensure that the pilot
will be alerted to all traffic under radar coverage, but
the actual altitude difference may be substantial.
Therefore, visual acquisition may be difficult in this
instance.
(d) Coverage Limitations. Since TIS is
provided by ground −based, secondary surveillance
radar, it is subject to all limitations of that radar. If an
aircraft is not detected by the radar, it cannot be
displayed on TIS. Examples of these limitations are
as follows:
(1)TIS will typically be provided within
55 NM of the radars depicted in FIG 4−5−5, Terminal
Mode S Radar Sites. This maximum range can vary
by radar site and is always subject to “line of sight”limitations; the radar and data link signals will be
blocked by obstructions, terrain, and curvature of the
earth.
(2)TIS will be unavailable at low altitudes
in many areas of the country, particularly inmountainous regions. Also, when flying near the
“floor” of radar coverage in a particular area,
intruders below the client aircraft may not be detected
by TIS.
(3)TIS will be temporarily disrupted when
flying directly over the radar site providing coverage
if no adjacent site assumes the service. Aground−based radar, like a VOR or NDB, has a zenith
cone, sometimes referred to as the cone of confusion
or cone of silence. This is the area of ambiguitydirectly above the station where bearing information
is unreliable. The zenith cone setting for TIS is
34 degrees: Any aircraft above that angle withrespect to the radar horizon will lose TIS coverage
from that radar until it is below this 34 degree angle.
The aircraft may not actually lose service in areas ofmultiple radar coverage since an adjacent radar will
provide TIS. If no other TIS −capable radar is
available, the “Good −bye” message will be received
and TIS terminated until coverage is resumed.
(e) Intermittent Operations. TIS operation
may be intermittent during turns or other maneuver-ing, particularly if the transponder system does not
include antenna diversity (antenna mounted on the
top and bottom of the aircraft). As in (d) above, TISis dependent on two −way, “line of sight” communica-
tions between the aircraft and the Mode S radar.
Whenever the structure of the client aircraft comesbetween the transponder antenna (usually located on
the underside of the aircraft) and the ground −based
radar antenna, the signal may be temporarilyinterrupted.
(f) TIS Predictive Algorithm. TIS informa-
tion is collected one radar scan prior to the scan
during which the uplink occurs. Therefore, thesurveillance information is approximately 5 seconds
old. In order to present the intruders in a “real time”
position, TIS uses a “predictive algorithm” in itstracking software. This algorithm uses track history
data to extrapolate intruders to their expected
positions consistent with the time of display in the
cockpit. Occasionally, aircraft maneuvering will
cause this algorithm to induce errors in the TISdisplay. These errors primarily af fect relative bearing
information; intruder distance and altitude will
remain relatively accurate and may be used to assistin “see and avoid.” Some of the more common
examples of these errors are as follows:
(1)When client or intruder aircraft maneu-
ver excessively or abruptly, the tracking algorithmwill report incorrect horizontal position until the
maneuvering aircraft stabilizes.
(2)When a rapidly closing intruder is on a
course that crosses the client at a shallow angle (either
overtaking or head on) and either aircraft abruptly
changes course within ¼ NM, TIS will display the
intruder on the opposite side of the client than itactually is.
These are relatively rare occurrences and will be
corrected in a few radar scans once the course has
stabilized.
(g) Heading/Course Refer ence. Not all TIS
aircraft installations will have onboard heading
reference information. In these installations, aircraft
course reference to the TIS display is provided by the
AIM 10/12/17
4−5−14 Surveillance SystemsMode S radar. The radar only determines ground
track information and has no indication of the client
aircraft heading. In these installations, all intruder
bearing information is referenced to ground track and
does not account for wind correction. Additionally,since ground −based radar will require several scans
to determine aircraft course following a course
change, a lag in TIS display orientation (intruderaircraft bearing) will occur. As in (f) above, intruder
distance and altitude are still usable.
(h) Closely −Spaced Intruder Errors.
When operating more than 30 NM from the Mode S
sensor, TIS forces any intruder within 3/8 NM of the
TIS client to appear at the same horizontal position asthe client aircraft. Without this feature, TIS could
display intruders in a manner confusing to the pilot in
critical situations (e.g., a closely −spaced intruder that
is actually to the right of the client may appear on the
TIS display to the left). At longer distances from the
radar, TIS cannot accurately determine relative
bearing/distance information on intruder aircraft that
are in close proximity to the client.
Because TIS uses a ground −based, rotating radar for
surveillance information, the accuracy of TIS data is
dependent on the distance from the sensor (radar)providing the service. This is much the same
phenomenon as experienced with ground −based
navigational aids, such as VOR or NDB. As distance
from the radar increases, the accuracy of surveillance
decreases. Since TIS does not inform the pilot of
distance from the Mode S radar, the pilot must assume
that any intruder appearing at the same position as the
client aircraft may actually be up to 3/8 NM away in
any direction. Consistent with the operation of TIS,an alert on the display (regardless of distance from the
radar) should stimulate an outside visual scan,
intruder acquisition, and traffic avoidance based on
outside reference.
e. Reports of TIS Malfunctions.
1.Users of TIS can render valuable assistance in
the early correction of malfunctions by reporting their
observations of undesirable performance. Reportersshould identify the time of observation, location, type
and identity of aircraft, and describe the condition
observed; the type of transponder processor, andsoftware in use can also be useful information. Since
TIS performance is monitored by maintenance
personnel rather than ATC, it is suggested thatmalfunctions be reported by radio or telephone to the
nearest Flight Service Station (FSS) facility.
4−5−7. Automatic Dependent
Surveillance −Broadcast (ADS −B) Services
a. Introduction.
1.Automatic Dependent Surveillance −Broad-
cast (ADS −B) is a surveillance technology deployed
throughout the NAS (see FIG 4−5−7). The ADS −B
system is composed of aircraft avionics and a ground
infrastructure. Onboard avionics determine theposition of the aircraft by using the GNSS and
transmit its position along with additional informa-
tion about the aircraft to ground stations for use by
ATC and other ADS −B services. This information is
transmitted at a rate of approximately once per
second. (See FIG 4−5−8 and FIG 4−5−9.)
2.In the United States, ADS −B equipped
aircraft exchange information is on one of two
frequencies: 978 or 1090 MHz. The 1090 MHz
frequency is associated with Mode A, C, and Stransponder operations. 1090 MHz transponders
with integrated ADS −B functionality extend the
transponder message sets with additional ADS −B
information. This additional information is known
as an “extended squitter” message and referred to as
1090ES. ADS −B equipment operating on 978 MHz
is known as the Universal Access T ransceiver (UAT).
3.ADS B avionics can have the ability to both
transmit and receive information. The transmission
of ADS−B information from an aircraft is known as
ADS−B Out. The receipt of ADS −B information by
an aircraft is known as ADS −B In. On January 1,
2020, all aircraft operating within the airspacedefined in 14 CFR Part 91 § 91.225 will be required
to transmit the information defined in § 91.227
using ADS −B Out avionics.
4.In general, operators flying at 18,000 feet and
above will require equipment which uses 1090 ES.
Those that do not fly above 18,000 may use either
UAT or 1090ES equipment. (Refer to 14 CFR 91.225and 91.227.) While the regulation will not require it,
operators equipped with ADS −B In will realize
additional benefits from ADS −B broadcast services:
Traffic Information Service – Broadcast (TIS −B)
(Paragraph 4 −5−8) and Flight Information Service −
Broadcast (FIS −B) (Paragraph 4 −5−9).
AIM 10/12/17
4−5−15 Surveillance SystemsFIG 4−5−7
ADS−B, TIS−B, and FIS −B:
Broadcast Services Architecture
b. ADS−B Certification and Performance
Requirements.
ADS−B equipment may be certified as a surveillance
source for air traffic separation services using
ADS−B Out. ADS −B equipment may also be
certified for use with ADS −B In advisory services
that enable appropriately equipped aircraft to
display traffic and flight information. Refer to the
aircraft’s flight manual supplement or PilotOperating Handbook for the capabilities of a specific
aircraft installation.c. ADS−B Capabilities and Procedures.
1.ADS−B enables improved surveillance ser-
vices, both air −to−air and air −to−ground, especially
in areas where radar is ineffective due to terrain orwhere it is impractical or cost prohibitive. Initial NAS
applications of air −to−air ADS−B are for “advisory”
use only, enhancing a pilot’s visual acquisition ofother nearby equipped aircraft either when airborne
or on the airport surface. Additionally, ADS −B will
enable ATC and fleet operators to monitor aircraftthroughout the available ground station coverage
area.
AIM 10/12/17
4−5−16 Surveillance SystemsFIG 4−5−8
En Route − ADS−B/ADS−R/TIS−B/FIS−B Service Ceilings/Floors
FIG 4−5−9
Terminal − ADS−B/ADS−R/TIS−B/FIS−B Service Ceilings/Floors
AIM 10/12/17
4−5−17 Surveillance Systems2.An aircraft’s Flight Identification (FLT ID),
also known as registration number or airline flight
number, is transmitted by the ADS-B Out avionics.
The FLT ID is comprised of a maximum of seven
alphanumeric characters and also corresponds to theaircraft identification annotated on the ATC flight
plan. The FLT ID for airline and commuter aircraft is
associated with the company name and flight number
(for example, AAL3342). The FLT ID is typically
entered by the flightcrew during preflight through
either a Flight Management System (FMS) interface(Control Display Unit/CDU) or transponder control
panel. The FLT ID for General A viation (GA) aircraft
is associated with the aircraft’s registration number.The aircraft owner can preset the FLT ID to the
aircraft’s registration number (for example,
N235RA), since it is a fixed value, or the pilot canenter it into the ADS-B Out system prior to flight.
ATC systems use transmitted FLT IDs to uniquely
identify each aircraft within a given airspace andcorrelate them to a filed flight plan for the provision
of surveillance and separation services. If the FLT ID
is not entered correctly, ATC automation systemsmay not associate surveillance tracks for the aircraft
to its filed flight plan. Therefore, Air Traffic services
may be delayed or unavailable until this is corrected.
Consequently, it is imperative that flightcrews and
GA pilots ensure the FLT ID entry correctly matchesthe aircraft identification annotated in the filed ATC
flight plan.
3.Each ADS −B aircraft is assigned a unique
ICAO address (also known as a 24 −bit address) that
is broadcast by the ADS −B transmitter. The ICAO
address is programmable at installation. Shouldmultiple aircraft broadcast the same ICAO address
while transiting the same ADS −B Only Service
V olume, the ADS−B network may be unable to track
the targets correctly. If radar reinforcement is
available, tracking will continue. If radar is
unavailable, the controller may lose target trackingentirely on one or both targets. Consequently, it is
imperative that the ICAO address entry is correct.
Aircraft that is equipped with ADS −B avionics on the
UAT datalink have a feature that allows it to broadcast
an anonymous 24 −bit ICAO address. In this mode,
the UAT system creates a randomized address thatdoes not match the actual ICAO address assigned to
the aircraft. After January 1, 2020, and in the airspace
identified in § 91.225, the UAT anonymous 24 −bitaddress feature may only be used when the operator
has not filed a flight plan and is not requesting ATC
services. In the anonymity mode, the aircraft’s
beacon code must set to 1200, and depending on the
manufacturer’s implementation, the aircraft’s callsign might not be transmitted. Operators should be
aware that in UAT anonymous mode they will not be
eligible to receive ATC separation and flightfollowing services, and will likely not benefit from
enhanced ADS −B search and rescue capabilities.
4.ADS−B systems integrated with the
transponder will automatically set the applicable
emergency status when 7500, 7600, or 7700 are
entered into the transponder. ADS B systems notintegrated with the transponder, or systems with
optional emergency codes, will require that the
appropriate emer gency code is entered through a pilot
interface. ADS−B is intended for in −flight and
airport surface use. ADS −B systems should be
turned “on” −− and remain “on” −− whenever
operating in the air and moving on the airport
surface. Civil and military Mode A/C transpon-ders and ADS−B systems should be adjusted to the
“on” or normal operating position as soon as
practical , unless the change to “standby” has been
accomplished previously at the request of ATC.
d. ATC Surveillance Services using ADS −B −
Procedures and Recommended Phraseology
Radar procedures, with the exceptions found in this
paragraph, are identical to those procedures pre-
scribed for radar in AIM Chapter 4 and Chapter 5.
1.Preflight:
If a request for ATC services is predicated on ADS −B
and such services are anticipated when either a VFR
or IFR flight plan is filed, the aircraft’s FLT ID as
entered in Item 7 of the ICAO flight plan (Block 2 of
FAA domestic flight plan) must be entered in the
ADS−B avionics.
2.Inflight:
When requesting ADS −B services while airborne,
pilots should ensure that their ADS −B equipment is
transmitting their aircraft’s registration number orthe approved FAA/ICAO company or or ganizational
designator, prior to contacting ATC. Aircraft
equipped with a “VFR” or anonymous feature, willnot broadcast the appropriate aircraft identification
information and should disable the anonymous
feature before contacting ATC.
AIM 10/12/17
4−5−18 Surveillance Systems3.Aircraft with an Inoperative/Malfunctioning
ADS−B Transmitter:
(a)ATC will inform the flight crew when the
aircraft’s ADS −B transmitter appears to be inopera-
tive or malfunctioning:
PHRASEOLOGY −
YOUR ADS −B TRANSMITTER APPEARS TO BE
INOPERATIVE/MALFUNCTIONING. STOP ADS −B
TRANSMISSIONS.
(b)ATC will inform the flight crew if it
becomes necessary to turn off the aircraft’s ADS −B
transmitter.
PHRASEOLOGY −
STOP ADS −B TRANSMISSIONS.
(c)Other malfunctions and considerations:
Loss of automatic altitude reporting capabilities
(encoder failure) will result in loss of ATC altitude
advisory services.
e. ADS−B Limitations.
1.The ADS−B cockpit display of traffic is NOT
intended to be used as a collision avoidance system
and does not relieve the pilot’s responsibility to “see
and avoid” other aircraft. (See paragraph 5 −5−8, See
and Avoid). ADS −B must not be used for avoidance
maneuvers during IMC or other times when there is
no visual contact with the intruder aircraft. ADS −B is
intended only to assist in visual acquisition of other
aircraft. No avoidance maneuvers are provided nor
authorized, as a direct result of an ADS −B target
being displayed in the cockpit.
2.Use of ADS −B radar services is limited to the
service volume of the GBT.
NOTE−
The coverage volume of GBT s are limited to line −of−sight.
f. Reports of ADS −B Malfunctions.
Users of ADS −B can provide valuable assistance in
the correction of malfunctions by reporting instances
of undesirable system performance. Since ADS-B
performance is monitored by maintenance personnel
rather than ATC, report malfunctions to the nearest
Flight Service Station (FSS) facility by radio or
telephone. Reporters should identify:
1.Condition observed.
2.Date and time of observation.
3.Altitude and location of observation.4.Type and call sign of the aircraft.
5.Type and software version of avionics
system.
4−5−8. Traffic Information Service −
Broadcast (TIS −B)
a. Introduction
TIS−B is the broadcast of ATC derived traffic
information to ADS −B equipped (1090ES or UAT)
aircraft from ground radio stations. The source of this
traffic information is derived from ground −based air
traffic surveillance sensors. TIS −B service will be
available throughout the NAS where there are both
adequate surveillance coverage from ground sensors
and adequate broadcast coverage from ADS −B
ground radio stations. The quality level of traffic
information provided by TIS −B is dependent upon
the number and type of ground sensors available asTIS−B sources and the timeliness of the reported
data. (See FIG 4−5−8 and FIG 4−5−9.)
b. TIS−B Requir ements.
In order to receive TIS −B service, the following
conditions must exist:
1.Aircraft must be equipped with an ADS −B
transmitter/receiver or transceiver, and a cockpit
display of traffic information (CDTI).
2.Aircraft must fly within the coverage volume
of a compatible ground radio station that is
configured for TIS −B uplinks. (Not all ground radio
stations provide TIS −B due to a lack of radar
coverage or because a radar feed is not available).
3.Aircraft must be within the coverage of and
detected by at least one ATC
radar serving the ground
radio station in use.
c. TIS−B Capabilities.
1.TIS−B is intended to provide ADS −B
equipped a ircraft with a more complete tra ffic picture
in situations where not all nearby aircraft are
equipped with ADS −B Out. This advisory −only
application is intended to enhance a pilot’s visual
acquisition of other traffic.
2.Only transponder −equipped targets
(i.e., Mode A/C or Mode S transponders) aretransmitted through the ATC ground system
architecture. Current radar siting may result in
limited radar surveillance coverage at lower
AIM 10/12/17
4−5−19 Surveillance Systemsaltitudes near some airports, with subsequently
limited TIS −B service volume coverage. If there is
no radar coverage in a given area, then there will be
no TIS−B coverage in that area.
d. TIS−B Limitations.
1.TIS−B is NOT intended to be used as a
collision avoidance system and does not relieve thepilot’s responsibility to “see and avoid” other aircraft,
in accordance with 14CFR §91.113b. TIS −B must
not be used for avoidance maneuvers during timeswhen there is no visual contact with the intruder
aircraft. TIS −B is intended only to assist in the visual
acquisition of other aircraft.
NOTE−
No aircraft avoidance maneuvers are authorized as a
direct result of a TIS −B target being displayed in the
cockpit.
2.While TIS −B is a useful aid to visual traffic
avoidance, its inherent system limitations must be
understood to ensure proper use.
(a)A pilot may receive an intermittent TIS −B
target of themselves, t ypically when maneuvering
(e.g., climbing turns) due to the radar not trackingthe aircraft as quickly as ADS −B.
(b)The ADS −B−to−radar association pro-
cess within the ground system may at times have
difficulty correlating an ADS −B report with
corresponding radar returns from the same aircraft.
When this happens the pilot may see duplicate traffic
symbols (i.e., “TIS −B shadows”) on the cockpit
display.
(c)Updates of TIS −B traffic reports will
occur less often than ADS −B traffic updates. TIS −B
position updates will occur approximately once
every 3−13 seconds depending on the type of radar
system in use within the coverage area. Incomparison, the update rate for ADS −B is nominally
once per second.
(d)The TIS−B system only uplinks data
pertaining to transponder −equipped aircraft. Aircraft
without a transponder will not be displayed as TIS −B
traffic.
(e)There is no indication provided when any
aircraft is operating inside or outside the TIS −Bservice volume, therefore it is difficult to know if one
is receiving uplinked TIS −B traffic information.
3.Pilots and operators are reminded that the
airborne equipment that displays TIS −B targets is for
pilot situational awareness only and is not approved
as a collision avoidance tool. Unless there is an
imminent emergency requiring immediate action,any deviation from an air traffic control clearance in
response to perceived converging traffic appearing
on a TIS −B display must be approved by the
controlling ATC facility before commencing the
maneuver, except as permitted under certain
conditions in 14CFR §91.123. Uncoordinateddeviations may place an aircraft in close proximity to
other aircraft under ATC control not seen on the
airborne equipment and may result in a pilotdeviation or other incident.
e. Reports of TIS −B Malfunctions.
Users of TIS −B can provide valuable assistance in the
correction of malfunctions by reporting instances ofundesirable system performance. Since TIS −B
performance is monitored by maintenance personnel
rather than ATC, report malfunctions to the nearestFlight Service Station (FSS) facility by radio or
telephone. Reporters should identify:
1.Condition observed.
2.Date and time of observation.
3.Altitude and location of observation.
4.Type and call sign of the aircraft.
5.Type and software version of avionics
system.
4−5−9. Flight Information Service −
Broadcast (FIS −B)
a. Introduction.
FIS−B is a ground broadcast service provided
through the ADS −B Services network over the
978 MHz UAT data link. The FAA FIS −B system
provides pilots and flight crews of properly equipped
aircraft with a cockpit display of certain aviation
weather and aeronautical information. FIS −B recep-
tion is line−of−sight within the service volume of the
ground infrastructure. (See FIG 4−5−8 and
FIG 4−5−9.)
AIM 10/12/17
4−5−20 Surveillance Systemsb. Weather Products.
FIS-B does not replace a preflight weather briefing
from a source listed in Paragraph 7 −1−2, FAA
Weather Services, or inflight updates from an FSS or
ATC. FIS-B information may be used by the pilot for
the safe conduct of flight and aircraft movement;
however, the information should not be the only
source of weather or aeronautical information. A
pilot should be particularly alert and understand thelimitations and quality assurance issues associated
with individual products. This includes graphical
representation of next generation weather radar(NEXRAD) imagery and Notices to Airmen
(NOTAM)/temporary flight restrictions (TFR).
REFERENCE −
AIM, Paragraph 7 −1−11 , Flight Information Services
Advisory Circular (AC) 00 −63, “Use of Cockpit Displays of Digital
Weather and Aeronautical Information”c. Reports of FIS −B Malfunctions.
Users of FIS −B can provide valuable assistance in the
correction of malfunctions by reporting instances of
undesirable system performance. Since FIS −B
performance is monitored by maintenance personnel
rather than ATC, report malfunctions to the nearest
Flight Service Station (FSS) facility by radio ortelephone. Reporters should identify:
1.Condition observed.
2.Date and time of observation.
3.Altitude and location of observation.
4.Type and call sign of the aircraft.
5.Type and software version of avionics
system.
TBL 4−5−3
FIS−B Basic Product Update and Transmission Intervals
ProductFIS−B Service
Update Interval1FIS−B Service
Transmission Interval2
AIRMET As available 5 minutes
Convective SIGMET As available 5 minutes
METAR/SPECI Hourly/as available 5 minutes
NEXRAD Reflectivity (CONUS) 5 minutes 15 minutes
NEXRAD Reflectivity (Regional) 5 minutes 2.5 minutes
NOTAM−D/FDC As available 10 minutes
PIREP As available 10 minutes
SIGMET As available 5 minutes
SUA Status As available 10 minutes
TAF/AMEND 8 hours/as available 10 minutes
Temperature Aloft 6 hours 10 minutes
Winds Aloft 6 hours 10 minutes
1 The Update Interval is the rate at which the product data is available from the source.
2 The Transmission Interval is the amount of time within which a new or updated product transmission must be
completed and the rate or repetition interval at which the product is rebroadcast.
NOTE−
Details concerning the content, format, and symbols of the various data link products provided should be obtained fromthe specific avionics manufacturer.
AIM 10/12/17
4−5−21 Surveillance Systems4−5−10. Automatic Dependent
Surveillance −Rebroadcast (ADS −R)
a. Introduction.
ADS−R is a datalink translation function of the
ADS−B ground system required to accommodate the
two separate operating frequencies (978 MHz and1090 ES). The ADS −B system receives the ADS −B
messages transmitted on one frequency and ADS −R
translates and reformats the information forrebroadcast and use on the other frequency. This
allows ADS −B In equipped aircraft to see nearby
ADS−B Out traf fic regardless of the operating link of
the other aircraft. Aircraft operating on the same
ADS−B frequency exchange information directly
and do not require the ADS −R translation function.
(See FIG 4−5−8 and FIG 4−5−9.)b. Reports of ADS −R Malfunctions.
Users of ADS −R can provide valuable assistance in
the correction of malfunctions by reporting instances
of undesirable system performance. Since ADS −R
performance is monitored by maintenance personnel
rather than ATC, report malfunctions to the nearest
Flight Service Station (FSS) facility by radio ortelephone. Reporters should identify:
1.Condition observed.
2.Date and time of observation.
3.Altitude and location of observation.
4.Type and call sign of the aircraft.
5.Type and software version of avionics
system.
AIM 10/12/17
4−6−1 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRSection 6. Operational Policy/Procedures for Reduced
Vertical Separation Minimum (RVSM) in the Domestic
U.S., Alaska, Offshore Airspace and the San Juan FIR
4−6−1. Applicability and RVSM Mandate
(Date/Time and Area)
a. Applicability. The policies, guidance and
direction in this section apply to RVSM operations in
the airspace over the lower 48 states, Alaska, Atlantic
and Gulf of Mexico High Offshore Airspace and
airspace in the San Juan FIR where VHF or UHFvoice direct controller −pilot communication (DCPC)
is normally available. Policies, guidance and
direction for RVSM operations in oceanic airspace
where VHF or UHF voice DCPC is not available and
the airspace of other countries are posted on the FAA“RVSM Documentation” web page described in
Paragraph 4 −6−3, Aircraft and Operator Approval
Policy/Procedures, RVSM Monitoring and Data-bases for Aircraft and Operator Approval.
b. Mandate. At 0901 UTC on January 20, 2005,
the FAA implemented RVSM between flight
level (FL) 290 −410 (inclusive) in the following
airspace: the airspace of the lower 48 states of theUnited States, Alaska, Atlantic and Gulf of Mexico
High Of fshore Airspace and the San Juan FIR. On the
same time and date, RVSM was also introduced intothe adjoining airspace of Canada and Mexico to
provide a seamless environment for aircraft travers-
ing those borders. In addition, RVSM wasimplemented on the same date in the Caribbean and
South American regions.
c. RVSM Authorization. In accordance with
14 CFR Section 91.180, with only limited excep-
tions, prior to operating in RVSM airspace, operators
and aircraft must have received R VSM authorization
from the responsible civil aviation authority. (See
Paragraph 4 −6−10, Procedures for Accommodation
of Non−RVSM Aircraft.) If the operator or aircraft or
both have not been authorized for RVSM operations,
the aircraft will be referred to as a “non −RVSM”
aircraft. Paragraph 4 −6−10 discusses ATC policies
for accommodation of non −RVSM aircraft flown by
the Department of Defense, Air Ambulance
(MEDEV AC) operators, foreign State governments
and aircraft flown for certification and development.Paragraph 4 −6−11, Non−RVSM Aircraft Requesting
Climb to and Descent from Flight Levels Above
RVSM Airspace Without Intermediate Level Off,
contains policies for non −RVSM aircraft climbing
and descending through RVSM airspace to/fromflight levels above RVSM airspace.
d. Benefits. RVSM enhances ATC flexibility,
mitigates conflict points, enhances sector throughput,
reduces controller workload and enables crossing
traffic. Operators gain fu el savings and operating
efficiency benefits by flying at more fuel efficient
flight levels and on more user preferred routings.
4−6−2. Flight Level Orientation Scheme
Altitude assignments for direction of flight follow a
scheme of odd altitude assignment for magnetic
courses 000 −179 degrees and even altitudes for
magnetic courses 180 −359 degrees for flights up to
and including FL 410, as indicated in FIG 4−6−1.
FIG 4−6−1
Flight Level Orientation Scheme
NOTE−
Odd Flight Levels: Magnetic Course 000 −179 Degrees
Even Flight Levels: Magnetic Course 180 −359 Degrees.
AIM 10/12/17
4−6−2 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR4−6−3. Aircraft and Operator Approval
Policy/Procedures, RVSM Monitoring andDatabases for Aircraft and OperatorApproval
a. RVSM Authority . 14 CFR Section 91.180
applies to RVSM operations within the U.S. 14 CFR
Section 91.706 applies to RVSM operations outside
the U.S. Both sections require that the operator obtain
authorization prior to operating in RVSM airspace.
14 CFR Section 91.180 requires that, prior toconducting RVSM operations within the U.S., the
operator obtain authorization from the FAA or from
the responsible authority, as appropriate. In addition,it requires that the operator and the operator ’s aircraft
comply with the standards of 14 CFR Part 91
Appendix G (Operations in RVSM Airspace).
b. Sources of Information. Advisory Circular
(AC) 91−85, Authorization of Aircraft and Operators
for Flight in Reduced Vertical Separation Minimum
(RVSM) Airspace, and the FAA RVSM website.
c. TCAS Equipage. TCAS equipage require-
ments are contained in 14 CFR Sections 121.356,125.224, 129.18 and 135.189. Part 91 Appendix G
does not contain TCAS equipage requirements
specific to RVSM, however, Appendix G doesrequire that aircraft equipped with TCAS II and flown
in RVSM airspace be modified to incorporate
TCAS II Version 7.0 or a later version.
d. Aircraft Monitoring. Operators are required
to participate in the RVSM aircraft monitoring
program. The “Monitoring Requirements and
Procedures” section of the RVSM Documentationweb page contains policies and procedures for
participation in the monitoring program. Ground −
based and GPS −based monitoring systems are
available for the Domestic RVSM program.
Monitoring is a quality control program that enables
the FAA and other civil aviation authorities to assess
the in−service altitude −keeping performance of
aircraft and operators.
e. Purpose of RVSM Approvals Databases.
ATC does not use RVSM approvals databases todetermine whether or not a clearance can be issued
into RVSM airspace. RVSM program managers do
regularly review the operators and aircraft thatoperate in RVSM airspace to identify and investigate
those aircraft and operators flying in RVSM airspace,
but not listed on the RVSM approvals databases.f. Registration of U.S. Operators. When U.S.
operators and aircraft are granted RVSM authority,
the Separation Standards Group at the FAA T echnical
Center obtains PTRS operator and aircraft informa-
tion to update the FAA maintained U.S.Operator/Aircraft RVSM Approvals database. Basic
database operator and aircraft information can be
viewed on the R VSM Documentation web page in the
“RVSM Approvals” section.
4−6−4. Flight Planning into RVSM Airspace
a.Operators that do not file the correct aircraft
equipment suffix on the FAA or ICAO Flight Plan
may be denied clearance into RVSM airspace.Policies for the FAA Flight Plan are detailed in
subparagraph c below. Policies for the ICAO Flight
Plan are detailed in subparagraph d.
b.The operator will annotate the equipment block
of the FAA or ICAO Flight Plan with an aircraftequipment suffix indicating RVSM capability only
after the responsible civil aviation authority has
determined that both the operator and its aircraft areRVSM−compliant and has issued RVSM authoriza-
tion to the operator.
c.General Policies for FAA Flight Plan Equip-
ment Suffix. TBL 5 −1−3, Aircraft Suffixes, allows
operators to indicate that the aircraft has both RVSM
and Advanced Area Navigation (RNA V) capabilities
or has only RVSM capability.
1.The operator will annotate the equipment
block of the FAA Flight Plan with the appropriate
aircraft equipment suffix from TBL 5 −1−3.
2.Operators can only file one equipment suffix
in block 3 of the FAA Flight Plan. Only thisequipment suffix is displayed directly to the
controller.
3.Aircraft with RNA V Capability. For flight in
RVSM airspace, aircraft with RNA V capability, but
not Advanced RNA V capability, will file “/W”. Filing
“/W” will not preclude such aircraft from filing and
flying direct routes in en route airspace.
d.Policy for ICAO Flight Plan Equipment
Suffixes.
1.Operators/aircraft that are RVSM −compliant
and that file ICAO flight plans will file “/W” in
block 10 (Equipment) to indicate RVSM authoriza-
tion and will also file the appropriate ICAO Flight
AIM 10/12/17
4−6−3 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRPlan suffixes to indicate navigation and communica-
tion capabilities. The equipment suffixes in
TBL 5−1−3 are for use only in an FAA Flight Plan
(FAA Form 7233 −1).
2.Operators/aircraft that file ICAO flight plans
that include flight in Domestic U.S. RVSM airspacemust file “/W” in block 10 to indicate RVSM
authorization.
e.Importance of Flight Plan Equipment Suffixes.
The operator must file the appropriate equipment
suffix in the equipment block of the FAA Flight Plan
(FAA Form 7233 −1) or the ICAO Flight Plan. The
equipment suffix informs ATC:
1.Whether or not the operator and aircraft are
authorized to fly in RVSM airspace.
2.The navigation and/or transponder capability
of the aircraft (e.g., advanced RNA V , transponder
with Mode C).
f.Significant ATC uses of the flight plan
equipment suffix information are:
1.To issue or deny clearance into RVSM
airspace.
2.To apply a 2,000 foot vertical separation
minimum in RVSM airspace to aircraft that are notauthorized for RVSM, but are in one of the limited
categories that the FAA has agreed to accommodate.
(See Paragraphs 4 −6−10, Procedures for Accommo-
dation of Non −RVSM Aircraft, and 4 −6−11,
Non−RVSM Aircraft Requesting Climb to and
Descent from Flight Levels Above RVSM AirspaceWithout Intermediate Level Off, for policy on limited
operation of unapproved aircraft in RVSM airspace).
3.To determine if the aircraft has “Advanced
RNA V” capabilities and can be cleared to fly
procedures for which that capability is required.
g.Improperly changing an aircraft equipment
suffix and/or adding “NON-RVSM” in the NOTES orREMARKS section (Field 18) while not removing
the “W” from Field 10, will not provide air traffic
control with the proper visual indicator necessary todetect Non-RVSM aircraft. To ensure information
processes correctly for Non-RVSM aircraft, the “W”
in Field 10 must be removed. Entry of information inthe NOTES or REMARKS section (Field 18) will not
affect the determination of RVSM capability and
must not be used to indicate a flight is Non-RVSM.4−6−5. Pilot RVSM Operating Practices and
Procedures
a. RVSM Mandate. If either the operator or the
aircraft or both have not received RVSM authoriza-
tion (non −RVSM aircraft), the pilot will neither
request nor accept a clearance into RVSM airspace
unless:
1.The flight is conducted by a non −RVSM
DOD, MEDEV AC, certification/development or
foreign State (government) aircraft in accordance
with Paragraph 4 −6−10, Procedures for Accommo-
dation of Non
−RVSM Aircraft.
2.The pilot intends to climb to or descend from
FL 430 or above in accordance with Para-
graph 4−6−11, Non−RVSM Aircraft Requesting
Climb to and Descent from Flight Levels AboveRVSM Airspace Without Intermediate Level Off.
3.An emergency situation exists.
b. Basic RVSM Operating Practices and
Procedures. Appendix B of AC 91 −85, Authoriza-
tion of Aircraft and Operators for Flight in ReducedVertical Separation Minimum Airspace, contains
pilot practices and procedures for RVSM. Operators
must incorporate Appendix B practices and proce-dures, as supplemented by the applicable paragraphs
of this section, into operator training or pilot
knowledge programs and operator documentscontaining RVSM operational policies.
c.Appendix B contains practices and procedures
for flight planning, preflight procedures at the
aircraft, procedures prior to RVSM airspace entry,
inflight (en route) procedures, contingency proce-dures and post flight.
d.The following paragraphs either clarify or
supplement Appendix B practices and procedures.
4−6−6. Guidance on Severe Turbulence
and Mountain Wave Activity (MWA)
a. Introduction/Explanation
1.The information and practices in this
paragraph are provided to emphasize to pilots andcontrollers the importance of taking appropriate
action in RVSM airspace when aircraft experience
severe turbulence and/or MWA that is of sufficientmagnitude to significantly affect altitude −keeping.
2. Severe Turbulence. Severe turbulence
causes large, abrupt changes in altitude and/or
AIM 10/12/17
4−6−4 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRattitude usually accompanied by large variations in
indicated airspeed. Aircraft may be momentarily out
of control. Encounters with severe turbulence must
be remedied immediately in any phase of flight.
Severe turbulence may be associated with MWA.
3. Mountain Wave Activity (MWA)
(a)Significant MWA occurs both below and
above the floor of RVSM airspace, FL 290. MWA
often occurs in western states in the vicinity ofmountain ranges. It may occur when strong winds
blow perpendicular to mountain ranges resulting in
up and down or wave motions in the atmosphere.Wave action can produce altitude excursions and
airspeed fluctuations accompanied by only light
turbulence. With sufficient amplitude, however,wave action can induce altitude and airspeed
fluctuations accompanied by severe turbulence.
MWA is difficult to forecast and can be highlylocalized and short lived.
(b)Wave activity is not necessarily limited to
the vicinity of mountain ranges. Pilots experiencingwave activity anywhere that significantly affects
altitude−keeping can follow the guidance provided
below.
(c)Inflight MWA Indicators (Including Tur-
bulence). Indicators that the aircraft is being
subjected to MWA are:
(1)Altitude excursions and/or airspeed
fluctuations with or without associated turbulence.
(2)Pitch and trim changes required to
maintain altitude with accompanying airspeedfluctuations.
(3)Light to severe turbulence depending
on the magnitude of the MWA.
4. Priority for Controller Application of
Merging Target Procedures
(a) Explanation of Merging Target Proce-
dures. As described in subparagraph c3 below, ATC
will use “merging target procedures” to mitigate the
effects of both severe turbulence and MWA. The
procedures in subparagraph c3 have been adaptedfrom existing procedures published in FAA Order JO
7110.65, Air Traffic Control, Paragraph 5 −1−8,
Merging Target Procedures. Paragraph 5 −1−8 calls
for en route controllers to advise pilots of potential
traffic that they perceive may fly directly above or
below his/her aircraft at minimum vertical separa-tion. In response, pilots are given the option of
requesting a radar vector to ensure their radar target
will not merge or overlap with the traffic’s radar
target.
(b)The provision of “merging target proce-
dures” to mitigate the effects of severe turbulence
and/or MWA is not optional for the controller, butrather is a priority responsibility. Pilot requests for
vectors for traffic avoidance when encountering
MWA or pilot reports of “Unable RVSM dueturbulence or MWA” are considered first priority
aircraft separation and sequencing responsibilities.
(FAA Order JO 7110.65, Paragraph 2 −1−2, Duty
Priority, states that the controller’s first priority is to
separate aircraft and issue safety alerts).
(c)Explanation of the term “traffic permit-
ting.” The contingency actions for MWA and severe
turbulence detailed in Paragraph 4 −6−9, Contingency
Actions: Weather Encounters and Aircraft System
Failures that Occur After Entry into R VSM Airspace,
state that the controller will “vector aircraft to avoid
merging targets with traffic at adjacent flight levels,
traffic permitting.” The term “traffic permitting” isnot intended to imply that merging target procedures
are not a priority duty. The term is intended to
recognize that, as stated in FAA Order JO 7110.65,Paragraph 2 −
1−2, Duty Priority, there are circum-
stances when the controller is required to perform
more than one action and must “exercise their best
judgment based on the facts and circumstances
known to them” to prioritize their actions. Furtherdirection given is: “That action which is most critical
from a safety standpoint is performed first.”
5. TCAS Sensitivity. For both MWA and
severe turbulence encounters in RVSM airspace, an
additional concern is the sensitivity of collisionavoidance systems when one or both aircraft
operating in close proximity receive TCAS advi-
sories in response to disruptions in altitude holdcapability.
b. Pre−flight tools. Sources of observed and
forecast information that can help the pilot ascertain
the possibility of MWA or severe turbulence are:Forecast Winds and Temperatures Aloft (FD), Area
Forecast (FA), Graphical Turbulence Guidance
(GTG), SIGMETs and PIREPs.
c. Pilot Actions When Encountering Weather
(e.g., Severe Turbulence or MWA)
AIM 10/12/17
4−6−5 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR1. Weather Encounters Inducing Altitude
Deviations of Approximately 200 feet. When the
pilot experiences weather induced altitude deviations
of approximately 200 feet, the pilot will contact ATC
and state “Unable RVSM Due (state reason)”(e.g., turbulence, mountain wave). See contingency
actions in paragraph 4 −6−9.
2. Severe Turbulence (including that associ-
ated with MWA). When pilots encounter severe
turbulence, they should contact ATC and report the
situation. Until the pilot reports clear of severeturbulence, the controller will apply merging target
vectors to one or both passing aircraft to prevent their
targets from merging:
EXAMPLE −
“Yankee 123, FL 310, unable RVSM due severeturbulence.”
“Yankee 123, fly heading 290; traffic twelve o’clock,10 miles, opposite direction; eastbound MD −80 at
FL 320” (or the controller may issue a vector to theMD−80 traffic to avoid Yankee 123).
3. MWA. When pilots encounter MWA, they
should contact ATC and report the magnitude and
location of the wave activity. When a controller
makes a merging targets traffic call, the pilot may
request a vector to avoid flying directly over or under
the traffic. In situations where the pilot is
experiencing altitude deviations of 200 feet or
greater, the pilot will request a vector to avoid traf fic.
Until the pilot reports clear of MWA, the controller
will apply merging target vectors to one or both
passing aircraft to prevent their targets from mer ging:
EXAMPLE −
“Yankee 123, FL 310, unable RVSM due mountain wave.”
“Yankee 123, fly heading 290; traffic twelve o’clock,
10 miles, opposite direction; eastbound MD −80 at
FL 320” (or the controller may issue a vector to theMD−80 traffic to avoid Yankee 123).
4. FL Change or Re −route. To leave airspace
where MWA or severe turbulence is being
encountered, the pilot may request a FL change
and/or re−route, if necessary.
4−6−7. Guidance on Wake Turbulence
a.Pilots should be aware of the potential for wake
turbulence encounters in R VSM airspace. Experiencegained since 1997 has shown that such encounters in
RVSM airspace are generally moderate or less in
magnitude.
b.Prior to DRVSM implementation, the FAA
established provisions for pilots to report wake
turbulence events in R VSM airspace using the NASA
Aviation Safety Reporting System (ASRS). A
“Safety Reporting” section established on the FAA
RVSM Documentation web page provides contacts,forms, and reporting procedures.
c.To date, wake turbulence has not been reported
as a significant factor in DRVSM operations.
European authorities also found that reports of wake
turbulence encounters did not increase significantly
after RVSM implementation (eight versus sevenreports in a ten −month period). In addition, they
found that reported wake turbulence was generally
similar to moderate clear air turbulence.
d.Pilot Action to Mitigate Wake Turbulence
Encounters
1.Pilots should be alert for wake turbulence
when operating:
(a)In the vicinity of aircraft climbing or
descending through their altitude.
(b)Approximately 10 −30 miles after passing
1,000 feet below opposite −direction traffic.
(c)Approximately 10 −30 miles behind and
1,000 feet below same −direction traffic.
2.Pilots encountering or anticipating wake
turbulence in DRVSM airspace have the option of
requesting a vector, FL change, or if capable, a lateral
offset.
NOTE−
1.Offsets of approximately a wing span upwind generally
can move the aircraft out of the immediate vicinity of
another aircraft’ s wake vortex.
2.In domestic U.S. airspace, pilots must r equest clear ance
to fly a lateral offset. Strategic lateral offsets flown in
oceanic airspace do not apply.
4−6−8. Pilot/Controller Phraseology
TBL 4−6−1 shows standard phraseology that pilots
and controllers will use to communicate in DRVSM
operations.
AIM 10/12/17
4−6−6 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRTBL 4−6−1
Pilot/Controller Phraseology
Message Phraseology
For a controller to ascertain the RVSM approval status of
an aircraft:(call sign) confirm RVSM approved
Pilot indication that flight is RVSM approved Affirm RVSM
Pilot report of lack of RVSM approval (non −RVSM status).
Pilot will report non −RVSM status, as follows:Negative RVSM, (supplementary information,
e.g., “Certification flight”).
a. On the initial call on any frequency in the RVSM
airspace and . . ..
b. In all requests for flight level changes pertaining to
flight levels within the RVSM airspace and . . ..c. In all read backs to flight level clearances pertaining
to flight levels within the RVSM airspace and . . ..
d. In read back of flight level clearances involving
climb and descent through RVSM airspace (FL 290 − 410).
Pilot report of one of the following after entry into RVSM
airspace: all primary altimeters, automatic altitude control
systems or altitude alerters have failed.
(See Paragraph 4 −6−9, Contingency Actions: Weather
Encounters and Aircraft System Failures that Occur AfterEntry into RVSM Airspace.)
NOTE−
This phrase is to be used to convey both the initial indication ofRVSM aircraft system failure and on initial contact on allfrequencies in RVSM airspace until the problem ceases to existor the aircraft has exited RVSM airspace.Unable RVSM Due Equipment
ATC denial of clearance into RVSM airspace Unable issue clearance into RVSM airspace, maintain FL
*Pilot reporting inability to maintain cleared flight level
due to weather encounter.
(See Paragraph 4 −6−9, Contingency Actions: Weather
Encounters and Aircraft System Failures that Occur AfterEntry into RVSM Airspace.).*Unable RVSM due (state reason) (e.g., turbulence,mountain wave)
ATC requesting pilot to confirm that an aircraft hasregained RVSM −approved status or a pilot is ready to
resume RVSMConfirm able to resume RVSM
Pilot ready to resume RVSM after aircraft system or
weather contingencyReady to resume RVSM
AIM 10/12/17
4−6−7 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR4−6−9. Contingency Actions: Weather
Encounters and Aircraft System Failuresthat Occur After Entry into RVSM Airspace
TBL 4−6−2 provides pilot guidance on actions to
take under certain conditions of aircraft systemfailure that occur after entry into RVSM airspace
and weather encounters. It also describes the
expected A TC controller actions in these situations. It
is recognized that the pilot and controller will use
judgment to determine the action most appropriate to
any given situation.
TBL 4−6−2
Contingency Actions: Weather Encounters and Aircraft System Failures that Occur After Entry into RVSM
Airspace
Initial Pilot Actions in Contingency Situations
Initial pilot actions when unable to maintain flight level (FL) or unsure of aircraft altitude −keeping
capability:
/C0083Notify ATC and request assistance as detailed below.
/C0083Maintain cleared flight level, to the extent possible, while evaluating the situation.
/C0083Watch for conflicting traffic both visually and by reference to TCAS, if equipped .
/C0083Alert nearby aircraft by illuminating exterior lights (commensurate with aircraft limitations).
Severe Turbulence and/or Mountain Wave Activity (MWA) Induced
Altitude Deviations of Approximately 200 feet
Pilot will: Controller will:
/C0083When experiencing severe turbulence and/or
MWA induced altitude deviations of
approximately 200 feet or greater, pilot will
contact ATC and state “Unable RVSM Due (statereason)” (e.g., turbulence, mountain wave)
/C0083If not issued by the controller, request vector
clear of traffic at adjacent FLs
/C0083If desired, request FL change or re −route
/C0083Report location and magnitude of turbulence or
MWA to ATC/C0083Vector aircraft to avoid merging target with
traffic at adjacent flight levels, traffic permitting
/C0083Advise pilot of conflicting traffic
/C0083Issue FL change or re −route, traffic permitting
/C0083Issue PIREP to other aircraft
See Paragraph 4 −6−6, Guidance on Severe
Turbulence and Mountain Wave Activity (MWA) for
detailed guidance.Paragraph 4 −6−6 explains “traffic permitting.”
AIM 10/12/17
4−6−8 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRMountain Wave Activity (MWA) Encounters − General
Pilot actions: Controller actions:
/C0083Contact ATC and report experiencing MWA
/C0083If so desired, pilot may request a FL change or
re−route
/C0083Report location and magnitude of MWA to ATC/C0083Advise pilot of conflicting traffic at adjacent FL
/C0083If pilot requests, vector aircraft to avoid merging
target with traffic at adjacent RVSM flight levels,traffic permitting
/C0083Issue FL change or re −route, traffic permitting
/C0083Issue PIREP to other aircraft
See paragraph 4 −6−6 for guidance on MWA. Paragraph 4 −6−6 explains “traffic permitting.”
NOTE−
MWA encounters do not necessarily result in altitude deviations on the order of 200 feet. The guidance below is
intended to address less significant MWA encounters.
Wake Turbulence Encounters
Pilot should: Controller should:
/C0083Contact ATC and request vector, FL change or,
if capable, a lateral offset/C0083Issue vector, FL change or lateral offset
clearance, traffic permitting
See Paragraph 4 −6−7, Guidance on Wake
Turbulence.Paragraph 4 −6−6 explains “traffic permitting.”
“Unable RVSM Due Equipment”
Failure of Automatic Altitude Control System, Altitude Alerter or All Primary Altimeters
Pilot will: Controller will:
/C0083Contact ATC and state “Unable RVSM Due
Equipment”
/C0083Request clearance out of RVSM airspace unless
operational situation dictates otherwise/C0083Provide 2,000 feet vertical separation or
appropriate horizontal separation
/C0083Clear aircraft out of RVSM airspace unless
operational situation dictates otherwise
One Primary Altimeter Remains Operational
Pilot will: Controller will:
/C0083Cross check stand −by altimeter
/C0083Notify ATC of operation with single primary
altimeter
/C0083If unable to confirm primary altimeter accuracy,
follow actions for failure of all primary altimeters/C0083Acknowledge operation with single primary
altimeter
AIM 10/12/17
4−6−9 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIRTransponder Failure
Pilot will: Controller will:
/C0083Contact ATC and request authority to continue
to operate at cleared flight level
/C0083Comply with revised ATC clearance, if issued/C0083Consider request to continue to operate at
cleared flight level
/C0083Issue revised clearance, if necessary
NOTE−
14 CFR Section 91.215 (ATC transponder and altitude
reporting equipment and use) regulates operation with the
transponder inoperative.
4−6−10. Procedures for Accommodation of
Non−RVSM Aircraft
a. General Policies for Accommodation of
Non−RVSM Aircraft
1.The RVSM mandate calls for only RVSM
authorized aircraft/operators to fly in designated
RVSM airspace with limited exceptions. The policies
detailed below are intended exclusively for use by
aircraft that the FAA has agreed to accommodate.They are not intended to provide other operators a
means to circumvent the normal RVSM approval
process.
2.If either the operator or aircraft or both have
not been authorized to conduct RVSM operations, the
aircraft will be referred to as a “non −RVSM” aircraft.
14 CFR Section 91.180 and Part 91 Appendix Genable the FAA to authorize a deviation to operate a
non−RVSM aircraft in RVSM airspace.
3.Non−RVSM aircraft flights will be handled
on a workload permitting basis. The vertical
separation standard applied between aircraft not
approved for RVSM and all other aircraft must be2,000 feet.
4. Required Pilot Calls. The pilot of non −
RVSM aircraft will inform the controller of the lack
of RVSM approval in accordance with the direction
provided in Paragraph 4 −6−8, Pilot/Controller
Phraseology.b. Categories of Non −RVSM Aircraft that may
be Accommodated
Subject to FAA approval and clearance, the following
categories of non −RVSM aircraft may operate in
domestic U.S. R VSM airspace provided they have an
operational transponder.
1.Department of Defense (DOD) aircraft.
2.Flights conducted for aircraft certification
and development purposes.
3.Active air ambulance flights utilizing a
“MEDEV AC” call sign.
4.Aircraft climbing/descending through
RVSM flight levels (without intermediate level off)
to/from FLs above R VSM airspace (Policies for these
flights are detailed in Paragraph 4 −6−11, Non−RVSM
Aircraft Requesting Climb to and Descent from
Flight Levels Above RVSM Airspace WithoutIntermediate Level Off.
5.Foreign State (government) aircraft.
c.Methods for operators of non −RVSM aircraft to
request access to RVSM Airspace. Operators may:
1. LOA/MOU. Enter into a Letter of Agree-
ment (LOA)/Memorandum of Understanding
(MOU) with the RVSM facility (the Air Traffic
facility that provides air traffic services in RVSM
airspace). Operators must comply with LOA/MOU.
2. File−and−Fly. File a flight plan to notify the
FAA of their intention to request access to RVSM
airspace.
NOTE−
Priority for access to RVSM airspace will be afforded to
RVSM compliant air craft, then File −and−Fly flights.
AIM 10/12/17
4−6−10 Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the
Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR4−6−11. Non −RVSM Aircraft Requesting
Climb to and Descent from Flight LevelsAbove RVSM Airspace WithoutIntermediate Level Off
a. File−and−Fly. Operators of Non −RVSM air-
craft climbing to and descending from RVSM flight
levels should just file a flight plan.
b.Non−RVSM aircraft climbing to and descend-
ing from flight levels above RVSM airspace will behandled on a workload permitting basis. The vertical
separation standard applied in RVSM airspace
between non −RVSM aircraft and all other aircraft
must be 2,000 feet.c.Non−RVSM aircraft climbing to/descending
from RVSM airspace can only be considered for
accommodation provided:
1.Aircraft is capable of a continuous climb/de-
scent and does not need to level off at an intermediate
altitude for any operational considerations and
2.Aircraft is capable of climb/descent at the
normal rate for the aircraft.
d. Required Pilot Calls. The pilot of non −RVSM
aircraft will inform the controller of the lack of
RVSM approval in accordance with the direction
provided in Paragraph 4 −6−8, Pilot/Controller
Phraseology.
AIM 10/12/17
4−7−1 Operational Policy/Procedures for the Gulf of Mexico 50 NM Lateral Separation InitiativeSection 7. Operational Policy/Procedures for the Gulf of
Mexico 50 NM Lateral Separation Initiative
4−7−1. Introduction and Background
a. Introduction. On 20 October 2011 at 0900
UTC, the Federal Aviation Administration (FAA),Serviciós a la Navegacion en el Espacio AéreoMexicano (SENEAM) and the Direccion General de
Aeronautica Civil (DGAC) Mexico implemented 50Nautical Mile (NM) lateral separation betweenaircraft authorized Required Navigation Perform-ance 10 (RNP 10) or RNP 4 operating in the Gulf ofMexico (GoMex) Oceanic Control Areas (CTA).Existing Air Traffic Services (ATS) routes and routeoperating policies did not change for this implement-
ation.
b. RNP 10 Versus RNA V 10 T erminology. “RNP
10” has the same meaning and application as “RNA V10”. The ICAO Performance-based Navigation(PBN) Manual (ICAO Doc 9613), V olume II, Part B,
Chapter 1 (Implementing RNA V 10, Designated andAuthorized as RNP 10) explains that the term “RNP10” was in use before the publication of the ICAOPBN Manual and the manual has “grandfathered in”its continued use when implementing an “RNA V 10”
navigation specification.
c. Background. 50 NM lateral separation was
first applied between aircraft authorized for RNP 10operations on the North Pacific Route System inApril 1998. Since that time, 50 NM lateral separation
has been expanded throughout the Pacific FlightInformation Regions (FIRs) and is currently appliedin other airspaces, including, starting in June 2008,the West Atlantic Route System. GoMex 50 NMlateral separation implementation will apply theexperience gained in those operations.
d. Control Ar eas (CTA) Affected. 50 NM lateral
separation is implemented in the following CTAs/FIRs/Upper Control Areas (UTA).
1The Houston Oceanic CTA/FIR and the
Gulf of Mexico portion of the Miami OceanicCTA/FIR.
(a)The Monterrey CTA and Merida High
CTA within the Mexico FIR/UTAe. Reference Material. Information useful for
flight planning and operations within the Gulf ofMexico under this 50 NM lateral separation initiative
can be found in the West Atlantic Route System, Gulf
of Mexico, and Caribbean Resource Guide for U.S.Operators located at www .faa.gov/about/office_org/
headquarters_offices/avs/offices/afs/afs400/afs470/media/WATRS.pdf. The Guide can also be foundthrough a web search for “WATRS, GOMEX,Caribbean Resource Guide.”
4−7−2. Lateral Separation Minima Applied
a.50 NM lateral separation is applied in the
GoMex CTA’s between aircraft authorized RNP 10 or
RNP 4 at all altitudes above the floor of controlledairspace.
b.The current lateral separation minima of 100
NM in the Houston, Monterrey and Merida CTAs,and 90 NM in the Miami Oceanic CTA will continues
to be applied between aircraft not authorized RNP 10or RNP 4.
4−7−3. Operation on Routes on the
Periphery of the Gulf of Mexico CTAs
Operations on certain routes that fall within the
boundaries of affected CTAs are not affected by theintroduction of 50 NM lateral separation. Operationon the following routes is not affected:
a.Routes that are flown by reference to ICAO
standard ground-based navigation aids (VOR,VOR/DME, NDB).
b.Special Area Navigation (RNA V) routes Q100,
Q102 and Q105 in the Houston, Jacksonville andMiami CTAs.
4−7−4. Provisions for Non −RNP 10 Aircraft
(Not Authorized RNP 10 or RNP 4)
a.Operators of aircraft not authorized RNP 10 (or
RNP 4) must annotate their ICAO flight plan for Gulf
of Mexico operations as follows:
Item 18: “STS/NON −RNP10” (no space between
letters and numbers).
AIM 10/12/17
4−7−2 Operational Policy/Procedures for the Gulf of Mexico 50 NM Lateral Separation Initiativeb.Pilots of Non −RNP 10 aircraft that operate in
GoMex CTA’s must report the lack of authorizationby stating “Negative RNP 10”:
1.On initial call to ATC in a GoMex CTA:
2.In read back of a clearance to climb to or
descend from cruise altitude. (See paragraph4−7−4 e); and
3.When approval status is requested by the
controller. (See paragraph 4 −7−8e . )
c.Use of flight plan item 18 codes
“PBN/A1” or
“PBN/L1” are restricted to operators and aircraft
specifically authorized for RNP 10 or RNP 4, asapplicable.
d.Non−RNP 10 operators/aircraft may file any
route at any altitude in a GoMex CTA. They will becleared to operate on their preferred routes andaltitudes as traffic permits. 50 NM lateral separationwill not be applied to Non −RNP 10 aircraft.
e.Non−RNP 10 aircraft are encouraged to operate
at altitudes above those where traffic is most dense(i.e., at/above FL 380), if possible. Non −RNP 10
aircraft should plan on completing their climb to ordescent from higher FLs within radar coverage, ifpossible.
4−7−5. Operator Action
In order to maximize operational flexibility provided
by 50 NM lateral separation, operators capable ofmeeting RNP 10 or RNP 4 that operate on oceanicroutes or areas in the GoMex CTA’s should obtainauthorization for RNP 10 or RNP 4 and annotate the
ICAO flight plan accordingly.
NOTE−
1.RNP 10 is the minimum “Navigation Specification
(NavSpec)” required for the application of 50 NM lateral
separation. RNP 4 is an operator option. Operators/air-craft authorized RNP 4 are not required to also obtainRNP 10 authorization.
2.“RNP navigation specification” (e.g., RNP 10) is the
term adopted in the ICAO Performance-based Navigation
(PBN) Manual (Doc 9613). It replaces the term “RNPtype”.4−7−6. RNP 10 or RNP 4 Authorization:
Policy and Procedures for Aircraft and
Operators
a.RNP NavSpecs Applicable To Oceanic Opera-
tions. In accordance with ICAO guidance, RNP 10and RNP 4 are the only NavSpecs applicable tooceanic and remote area operations. Other RNA V and
RNP NavSpecs are applicable to continental en route,terminal area and approach operations.
b.FAA Documents. Advisory Circular (AC)
90-105, Approval Guidance for RNP Operations and
Barometric Vertical Navigation in the U.S. NationalAirspace System and in Oceanic and RemoteContinental Airspace, provides operational approval
guidance for RNP 4 and 10. It identifies minimumaircraft capabilities and operator procedural andtraining requirements in order to qualify for RNP 4 or
10. AC 90-105 is consistent with the ICAO PBNManual discussed below. Pertinent FAA and ICAOdocuments are posted online in the West Atlantic
Route System, Gulf of Mexico and CaribbeanResource Guide for U.S. Operators described in
paragraph 4 −7−1.
c.ICAO Performance-based Navigation (PBN)
Manual (ICAO Doc 9613). Guidance for authoriza-tion of RNP 10 and RNP 4 is provided in ICAODoc 9613. RNP 10 is addressed in V olume II, Part B;
Chapter 1. RNP 4 is addressed in V olume II, Part C;Chapter 1.
d.RNP 10 and RNP 4 Job Aids. Operators and
authorities are encouraged to use the RNP 10 or RNP
4 Job Aids posted on the FAA Resource Guide forU.S. Operators described in paragraph 4 −7−1. For
U.S. operators, a set of RNP 10 and RNP 4 Job Aidsprovides references to FAA documents. An RNP 4Job Aid, references to the ICAO PBN Manual, isalso available on the ICAO European and NorthAtlantic Office website. These Job Aids address theoperational and airworthiness elements of aircraftand operator authorization and provide references toappropriate document paragraphs. The Job Aidsprovide a method for operators to develop andauthorities to track the operator/aircraft programelements required for RNP 10 or RNP 4authorization.
e.Qualification of Aircraft Equipped With a
Single Long-Range Navigation System (S-LRNS)For RNP 10 Operations In GoMex CTAs.
AIM 10/12/17
4−7−3 Operational Policy/Procedures for the Gulf of Mexico 50 NM Lateral Separation Initiative1.Background. S-LRNS operatio ns in the Gulf
of Mexico, the Caribbean Sea and the otherdesignated areas have been conducted for at least 25years. Provisions allowing aircraft equipage with aS-LRNS for operations in specified oceanic andoff-shore areas are contained in the followingsections of 14 Code of Federal Regulations (CFR):91.511, 121.351, 125.203 and 135.165.
2.ICAO PBN Manual Reference. In reference
to RNP 10 authorization, the ICAO PBN Manual,V olume II, Part B, Chapter 1, paragraph 1.3.6.2 states
that: “A State authority may approve the use of asingle LRNS in specific circumstances (e.g., NorthAtlantic MNPS and 14 CFR 121.351 (c) refer). AnRNP 10 approval is still required.”
3.Policy Development. The FAA worked with
the ICAO NACC Office (North American, CentralAmerican and Caribbean), State regulators and ATSproviders in the GoMex and Caribbean areas toimplement a policy for S-LRNS equipped aircraft toqualify for RNP 10 for GoMex operations. Allowing
S-LRNS equipped aircraft to qualify for RNP 10enables more operator aircraft to be authorized RNP10, thereby creating a more uniform operatingenvironment for the application of 50 NM lateralseparation. The factors considered were: theshortness of the legs outside the range of groundnavigation aids, the availability of radar and VHFcoverage in a large portion of GoMex airspace and the
absence of events attributed to S-LRNS in GoMexoperations.
4.Single LRNS/RNP 10 Authorization Limited
to Gulf of Mexico. At this time, qualification for RNP10 based on use of a single long-range navigationsystem (LRNS) only applies to Gulf of Mexicooperations. Any expansion of this provision will
require assessment and agreement by the appropriate
State authorities.
f.RNP 10 Time Limit for INS or IRU Only
Equipped Aircraft. Operators should review theirAirplane Flight Manual (AFM), AFM Supplement or
other appropriate documents and/or contact theairplane or avionics manufacturer to determine theRNP 10 time limit applicable to their aircraft. Theywill then need to determine its effect, if any, on theiroperation. Un less otherwise approved, the basic RNP
10 time limit is 6.2 hours between position updatesfor aircraft on which Inertial Navigation Systems(INS) or Inertial Reference Units (IRU) provide theonly source of long range navigation. Extended RNP
10 time limits of 10 hours and greater are alreadyapproved for many IRU systems. FAA AdvisoryCircular 90 −105 contains provisions for extending
RNP 10 time limits.
4−7−7. Flight Planning Requirements
Operators must make ICAO flight plan annotations
in accordance with this paragraph and, if applicable,Paragraph 4 −7−4, Provisions for Non −RNP 10
Aircraft (Not Authorized RNP 10 or RNP 4).
a.ICAO Flight Plan Requirement. ICAO flight
plans must be filed for operation on oceanic routesand areas in the Houston Oceanic CT A/FIR, the Gulf
of Mexico portion of the Miami CTA/FIR, theMonterrey CTA and Merida High CTA.
b.To inform ATC that they have obtained RNP 10
or RNP 4 authorization and are eligible for 50 NMlateral separation, operators must:
1.Annotate ICAO Flight Plan Item 10
(Equipment) with the letter “R” and
2.Annotate Item 18 (Other Information) with,
as appropriate, “PBN/A1” (for RNP10) or “PBN/L1”(for RNP4).
NOTE−
On the ICAO Flight Plan, the letter “R” in Item 10
indicates that the flight is authorized for PBN operations.
Item 18 PBN/ indicates the types of PBN capabilities thatare authorized.
c.50 NM lateral separation will only be applied to
operators/aircraft that annotate the ICAO flight planin accordance with this policy. (See 4 −7−7b . )
d.Operators that have not obtained RNP 10 or
RNP 4 authorization must not annotate ICAO flightplan Item 18 (Other information) with “PBN/A1” or“PBN/L1”, but must follow the practices detailed inparagraph 4 −7−4.
4−7−8. Pilot and Dispatcher Procedures:
Basic and In-flight ContingencyProcedures
a. Basic Pilot Procedures. The RNP 10 and
RNP 4 Job Aids contain references to pilot and, ifapplicable, dispatcher procedures contained inAdvisory Circular 90 −105 and ICAO PBN Manual,
V olume II, Parts B and C, Chapter 1.
b. ICAO Doc 4444, In-Flight Contingency
Procedures . Chapter 15 of ICAO Doc 4444
AIM 10/12/17
4−7−4 Operational Policy/Procedures for the Gulf of Mexico 50 NM Lateral Separation Initiative(Procedures for Air Navigation Services – Air Traffic
Management (PANS-ATM)) contains importantguidance for pilot training programs. Chapter 15includes Special Procedures for In-flight Contingen-cies in Oceanic Airspace, as well as WeatherDeviation Procedures. Chapter 15 covers in-flightdiversion and turn-back scenarios, loss of navigation
capability, and procedures to follow for weatheravoidance. This critical guidance is reprinted in theOceanic Operations section of the U.S. AeronauticalInformation Publication (AIP), the Internationalsection of the Notices to Airmen Publication, andFAA Advisory Circular 91-70, Oceanic and Remote
Continental Airspace Operations .
c. Strategic Lateral Offset Pr ocedures (SLOP).
Pilots should use SLOP procedures in the course ofregular oceanic operations. Guidance regardingSLOP, including how to perform the procedures, isprovided in the Oceanic Operations section of theU.S. AIP.
d. Pilot Report of Non −RNP 10 Status. The pilot
must report the lack of RNP 10 or RNP 4 status inaccordance with the following:
1.When the operator/aircraft is not authorized
RNP 10 or RNP 4 − see paragraph 4 −7−4.
2.If approval status is requested by the
controller − see paragraph 4 −7−8e .e. Pilot Statement of RNP 10 or RNP 4
Approval Status, If Requested. If requested by the
controller, the pilot must communicate approvalstatus using the following phraseology:
Controller Request:
(Call sign) confirm RNP 10 or 4 approved
Pilot Response:
“Affirm RNP 10 approved” or “Affirm RNP 4
approved,” as appropriate, or
“Negative RNP 10” (See paragraph 4 −7−4 for
Non−RNP 10 aircraft procedures.)
f. Pilot action when navigation system mal-
functions. In addition to the actions addressed in the
Oceanic Operations section of the U.S. AIP, whenpilots suspect a navigation system malfunction, thefollowing actions should be taken:
1.Immediately inform ATC of navigation
system malfunction or failure.
2.Accounting for wind drift, fly magnetic
compass heading to maintain track.
3.Request radar vectors from ATC, when
available.
AIM 10/12/17
5−1−1 PreflightChapter 5. Air Traffic Procedures
Section 1. Preflight
5−1−1. Preflight Preparation
a.Every pilot is urged to receive a preflight
briefing and to file a flight plan. This briefing should
consist of the latest or most current weather, airport,
and en route NA V AID information. Briefing service
may be obtained from an FSS either by telephone, byradio when airborne, or by a personal visit to the
station. Pilots with a current medical certificate in the
48 contiguous States may access Lockheed MartinFlight Services or the Direct User Access Terminal
System (DUATS) via the internet. Lockheed Martin
Flight Services and DUATS will provide preflightweather data and allow pilots to file domestic VFR or
IFR flight plans.
REFERENCE −
AIM, Paragraph 7 −1−2 , F AA Weather Services, lists DUATS vendors.
NOTE−
Pilots filing flight plans via “fast file” who desire to havetheir briefing recorded, should include a statement at the
end of the recording as to the source of their weather
briefing.
b.The information required by the FAA to process
flight plans is contained on FAA Form 7233 −1, Flight
Plan, or F AA Form 7233 −4, International Flight Plan.
The forms are available at all flight service stations.
Additional copies will be provided on request.
REFERENCE −
AIM, Paragraph 5 −1−4 , Flight Plan − VFR Flights
AIM, Paragraph 5 −1−8 , Flight Plan − IFR Flights
AIM, Paragraph 5 −1−9, International Flight Plan − IFR Flights
c.Consult an FSS, Lockheed Martin Flight
Services, or DUATS for preflight weather briefing.
d.FSSs are required to advise of pertinent
NOTAMs if a standard briefing is requested, but if
they are overlooked, don’t hesitate to remind the
specialist that you have not received NOTAMinformation.
NOTE−
NOTAMs which are known in sufficient time for
publication and are of 7 days duration or longer arenormally incorporated into the Notices to AirmenPublication and carried there until cancellation time. FDC
NOTAMs, which apply to instrument flight pr ocedur es, are
also included in the Notices to Airmen Publication up toand including the number indicated in the FDC NOTAM
legend. Printed NOTAMs are not provided during abriefing unless specifically requested by the pilot since the
FSS specialist has no way of knowing whether the pilot has
already checked the Notices to Airmen Publication prior to
calling. Remember to ask for NOTAMs in the Notices toAirmen Publication. This information is not normallyfurnished during your briefing.
REFERENCE −
AIM, Paragraph 5 −1−3 , Notice to Airmen (NOTAM) System
e.Pilots are urged to use only the latest issue of
aeronautical charts in planning and conducting flight
operations. Aeronautical charts are revised andreissued on a regular scheduled basis to ensure that
depicted data are current and reliable. In the
conterminous U.S., Sectional Charts are updatedevery 6 months, IFR En Route Charts every 56 days,
and amendments to civil IFR Approach Charts are
accomplished on a 56 −day cycle with a change notice
volume issued on the 28 −day midcycle. Charts that
have been superseded by those of a more recent date
may contain obsolete or incomplete flightinformation.
REFERENCE −
AIM, Paragraph 9 −1−4 , General Description of Each Chart Series
f.When requesting a preflight briefing, identify
yourself as a pilot and provide the following:
1. Type of flight planned; e.g., VFR or IFR.
2. Aircraft’s number or pilot’s name.
3. Aircraft type.4. Departure Airport.
5. Route of flight.
6. Destination.
7. Flight altitude(s).
8. ETD and ETE.
g.Prior to conducting a briefing, briefers are
required to have the background information listedabove so that they may tailor the briefing to the needs
of the proposed flight. The objective is to
communicate a “picture” of meteorological andaeronautical information necessary for the conduct of
a safe and efficient flight. Briefers use all available
AIM 10/12/17
5−1−2 Preflightweather and aeronautical information to summarize
data applicable to the proposed flight. They do not
read weather reports and forecasts verbatim unless
specifically requested by the pilot. FSS briefers do
not provide FDC NOTAM information for specialinstrument approach procedures unless specifically
asked. Pilots authorized by the FAA to use special
instrument approach pro cedures must specifically
request FDC NOTAM information for these
procedures. Pilots who receive the information
electronically will receive NOTAMs for special IAPs
automatically.
REFERENCE −
AIM, Paragraph 7 −1−5 , Preflight Briefings, contains those items of a
weather briefing that should be expected or requested.
h.FAA by 14 CFR Part 93, Subpart K, has
designated High Density Traffic Airports (HDTAs)
and has prescribed air traffic rules and requirements
for operating aircraft (excluding helicopter opera-tions) to and from these airports.
REFERENCE −
Chart Supplement U.S., Special Notices Section
AIM, Paragraph 4 −1−21 , Airport Reservation Operations and Special
Traffic Management Programs
i.In addition to the filing of a flight plan, if the
flight will traverse or land in one or more foreign
countries, it is particularly important that pilots leave
a complete itinerary with someone directly concerned
and keep that person advised of the flight’s progress.
If serious doubt arises as to the safety of the flight, that
person should first contact the FSS.
REFERENCE −
AIM, Paragraph 5 −1−11 , Flights Outside the U.S. and U.S. Territories
j.Pilots operating under provisions of 14 CFR
Part 135 on a domestic flight and not having an FAA
assigned 3 −letter designator, are urged to prefix the
normal registration (N) number with the letter “T” on
flight plan filing; e.g., TN1234B.
REFERENCE −
AIM, Paragraph 4 −2−4 , Aircraft Call Signs
5−1−2. Follow IFR Procedures Even When
Operating VFR
a.To maintain IFR proficiency, pilots are urged to
practice IFR procedures whenever possible, evenwhen operating VFR. Some suggested practices
include:
1.Obtain a complete preflight and weather
briefing. Check the NOTAMs.2.File a flight plan. This is an excellent low cost
insurance policy . The cost is the time it takes to fill it
out. The insurance includes the knowledge that
someone will be looking for you if you become
overdue at your destination.
3.Use current charts.
4.Use the navigation aids. Practice maintaining
a good course −keep the needle centered.
5.Maintain a constant altitude which is
appropriate for the direction of flight.
6.Estimate en route position times.
7.Make accurate and frequent position reports
to the FSSs along your route of flight.
b.Simulated IFR flight is recommended (under
the hood); however, pilots are cautioned to reviewand adhere to the requirements specified in 14 CFR
Section 91.109 before and during such flight.
c.When flying VFR at night, in addition to the
altitude appropriate for the direction of flight, pilots
should maintain an altitude which is at or above theminimum en route altitude as shown on charts. This
is especially true in mountainous terrain, where there
is usually very little ground reference. Do not dependon your eyes alone to avoid rising unlighted terrain,
or even lighted obstructions such as TV towers.
5−1−3. Notice to Airmen (NOTAM) System
a.Time-critical aeronautical information which
is of either a temporary nature or not sufficiently
known in advance to permit publication on
aeronautical charts or in other operational publica-tions receives immediate dissemination via the
National NOTAM System.
NOTE−
1.NOTAM information is that aeronautical information
that could affect a pilot’ s decision to make a flight. Itincludes such information as airport or aerodrome
primary runway closures, taxiways, ramps, obstructions,
communications, airspace, changes in the status ofnavigational aids, ILSs, radar service availability, andother information essential to planned en route, terminal,or landing operations.
2.NOTAM information is transmitted using standard
contractions to reduce transmission time. See TBL 5 −1−2
for a listing of the most commonly used contractions. For
a complete listing, see F AA JO Order 7340.2,Contractions.
b.NOTAM information is classified into five
categories. These are NOTAM (D) or distant, Flight
AIM 10/12/17
5−1−3 PreflightData Center (FDC) NOTAMs, Pointer NOTAMs,
Special Activity Airspace (SAA) NOTAMs, and
Military NOTAMs.
1. NOTAM (D) information is disseminated for
all navigational facilities that are part of the NationalAirspace System (NAS), all public use airports,
seaplane bases, and heliports listed in the Chart
Supplement U.S. The complete file of all NOTAM(D) information is maintained in a computer database
at the Weather Message Switching Center (WMSC),
located in Atlanta, Georgia. This category ofinformation is distributed automatically via Service
A telecommunications system. Air traffic facilities,
primarily FSSs, with Service A capability have
access to the entire WMSC database of NOTAMs.
These NOTAMs remain available via Service A forthe duration of their validity or until published. Once
published, the NOTAM data is deleted from the
system. NOTAM (D) information includes such data
as taxiway closures, personnel and equipment near or
crossing runways, and airport lighting aids that do not
affect instrument approach criteria, such as V ASI.
All NOTAM Ds must have one of the keywords listed
in TBL 5−1−1 as the first part of the text after the
location identifier.
2. FDC NOTAMs. On those occasions when
it becomes necessary to disseminate informationwhich is regulatory in nature, the National Flight Data
Center (NFDC), in Washington, DC, will issue an
FDC NOTAM. FDC NOT AMs contain such things as
amendments to published IAPs and other current
aeronautical charts. They are also used to advertise
temporary flight restrictions caused by such things as
natural disasters or lar ge-scale public events that may
generate a congestion of air traffic over a site.
NOTE−
1.DUATS vendors will provide FDC NOTAMs only upon
site-specific requests using a location identifier.
2.NOTAM data may not always be current due to the
changeable nature of national airspace system compo-
nents, delays inherent in processing information, andoccasional temporary outages of the U.S. NOTAM system.
While en route, pilots s hould contact FSSs and obtain
updated information for their route of flight anddestination.
3. Pointer NOTAMs. NOTAMs issued by a
flight service station to highlight or point out another
NOTAM, such as an FDC or NOTAM (D) NOTAM.
This type of NOTAM will assist users incross−referencing important information that may
not be found under an airport or NA V AID identifier.
Keywords in pointer NOTAMs must match the
keywords in the NOTAM that is being pointed out.
The keyword in pointer NOTAMs related toTemporary Flight Restrictions (TFR) must be
AIRSPACE.
4. SAA NOTAMs. These NOTAMs are issued
when Special Activity Airspace will be active outside
the published schedule times and when required by
the published schedule. Pilots and other users are stillresponsible to check published schedule times for
Special Activity Airspace as well as any NOTAMs
for that airspace.
5. Military NOTAMs. NOTAMs pertaining
to U.S. Air Force, Army, Marine, and Navy
navigational aids/airports that are part of the NAS.
c. Notices to Airmen Publication (NTAP). The
NTAP is published by Mission Support Services,
ATC Products and Publications, every 28 days. Dataof a permanent nature can be published in the NTAP
as an interim step between publication cycles of the
Chart Supplement U.S. and aeronautical charts. TheNTAP is divided into four parts:
1.Notices in part 1 are provided by ATC
Products and Publications. This part containsselected FDC NOTAMs that are expected to be in
effect on the effective date of the publication. This
part is divided into three sections:
(a)Section 1, Airway NOTAMs, reflects
airway changes that fall within an ARTCC’s
airspace.
(b)Section 2, Procedural NOTAMs.
(c)Section 3, General NOTAMs, contains
NOTAMs that are general in nature and not tied to aspecific airport/facility (for example, flight advisor-
ies and restrictions, open duration special security
instructions, and special flight rules area).
2.Part 2, provided by NFDC, contains Part 95
Revisions, Revisions to Minimum En Route IFR
Altitudes and Changeover Points.
3.Part 3, International NOTAMs, is divided into
two sections:
(a)Section 1, International Flight Prohibi-
tions, Potential Hostile Situations, and Foreign
Notices.
(b)Section 2, International Oceanic Airspace
Notices.
AIM 10/12/17
5−1−4 Preflight4.Part 4, Graphic Notices, compiled by ATC
Products and Publications from data provided by
FAA service area offices and other lines of business,
contains special notices and graphics pertaining to
almost every aspect of aviation such as: militarytraining areas, large scale sporting events, air showinformation, Special Traffic Management Programs
(STMP), and airport-specific information. This part
is comprised of 6 sections: General, Special Military
Operations, Airport and Facility Notices, Major
Sporting and Entertainment Events, Airshows, andSpecial Notices.
TBL 5−1−1
NOTAM Keywords
Keyword Definition
RWY .......
ExampleRunway
!BNA BNA RWY 36 CLSD 1309131300 −1309132000EST
TWY .......
ExampleTaxiway
!BTV BTV TWY C EDGE LGT OBSC 1310131300 −1310141300EST
APRON .....
ExampleApron/Ramp
!BNA BNA APRON NORTH APRON EAST SIDE CLSD 13111221500-1312220700
AD .........
ExampleAerodrome
!BET BET AD ELK NEAR MVMT AREAS 1309251300-1309262200EST
OBST .......
ExampleObstruction
!SJT SJT OBST MOORED BALLOON WITHIN AREA DEFINED AS 1NM RADIUS OF SJT 2430FT
(510FT AGL) FLAGGED 1309251400 −1309261400EST
NA V ........
ExampleNavigation Aids
!SHV SHV NA V ILS RWY 32 110.3 COMMISSIONED 1311251600-PERM
COM .......
ExampleCommunications
!INW INW COM REMOTE COM OUTLET 122.6 OUT OF SERVICE 1307121330-1307151930EST
SVC ........
ExampleServices
!ROA ROA SVC TWR COMMISSIONED 1301050001-PERM
AIRSPACE ..
ExampleAirspace
!MIV MIV AIRSPACE AIRSHOW ACFT WITHIN AREA DEFINED AS 5NM RADIUS OF MIV
SFC-10000FT A VOIDANCE ADVISED 1308122100-1308122300
ODP ........
ExampleObstacle Departure Procedure
!FDC 2/9700 DIK ODP DICKINSON - THEODORE ROOSEVELT RGNL, DICKINSON, ND.
TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES AMDT 1...DEPARTURE PROCEDURE: RWY 25, CLIMB HEADING 250 TO 3500 BEFORE TURNING LEFT. ALLOTHER DATA REMAINS AS PUBLISHED.THIS IS TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES, AMDT 1A.1305011200-PERM
SID .........
ExampleStandard Instrument Departure
!FDC x/xxxx DFW SID DALLAS/FORT WORTH INTL, DALLAS, TX.
PODDE THREE DEPARTURE...CHANGE NOTES TO READ: RWYS 17C/R, 18L/R: DO NOT EXCEED 240KT UNTIL LARRN. RWYS35L/C, 36L/R: DONOT EXCEED 240KT UNTIL KMART 1305011200-1312111200EST
STAR .......
ExampleStandard Terminal Arrival
!FDC x/xxxx DCA STAR RONALD REAGAN WASHINGTON NATIONAL,WASHINGTON, DC.
WZRRD TWO ARRIV AL...SHAAR TRANSITION: ROUTE FROM DRUZZ INT TO WZRRD INT NOT AUTHORIZED. AFTERDRUZZ INT EXPECT RADAR VECTORS TO AML VORTAC 1305011200-1312111200ES
AIM 10/12/17
5−1−5 PreflightKeyword Definition
CHART .....
ExampleChart
!FDC 2/9997 DAL IAP DALLAS LOVE FIELD, DALLAS, TX.
ILS OR LOC RWY 31R, AMDT 5...CHART NOTE: SIMULTANEOUS APPROACH AUTHORIZED WITH RWY 31L. MISSED APPROACH:CLIMB TO 1000 THEN CLIMBING RIGHT TURN TO 5000 ON HEADING 330 AND CVE R-046 TOFINGR INT/CVE 36.4 DME AND HOLD. CHART LOC RWY 31L.THIS IS ILS OR LOC RWY 31R, AMDT 5A. 1305011200-PERM
DATA .......
ExampleData
!FDC 2/9700 DIK ODP DICKINSON - THEODORE ROOSEVELT RGNL, DICKINSON, ND.
TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES AMDT 1...DEPARTURE PROCEDURE: RWY 25, CLIMB HEADING 250 TO 3500 BEFORE TURNING LEFT. ALLOTHER DATA REMAINS AS PUBLISHED. THIS IS TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES, AMDT 1A.1305011200-PERM
IAP .........
ExampleInstrument Approach Procedure
!FDC 2/9997 DAL IAP DALLAS LOVE FIELD, DALLAS, TX.
ILS OR LOC RWY 31R, AMDT 5...CHART NOTE: SIMULTANEOUS APPROACH AUTHORIZED WITH RWY 31L. MISSED APPROACH:CLIMB TO 1000 THEN CLIMBING RIGHT TURN TO 5000 ON HEADING 330 AND CVE R-046 TOFINGR INT/CVE 36.4 DME AND HOLD. CHART LOC RWY 31L.THIS IS ILS OR LOC RWY 31R, AMDT 5A. 1305011200-PERM
VFP ........
ExampleVisual Flight Procedures
!FDC X/XXXX JFK VFP JOHN F KENNEDY INTL, NEW YORK, NY .
PARKWAY VISUAL RWY 13L/R, ORIG...WEATHER MINIMUMS 3000 FOOT CEILING AND 3 MILESVISIBILITY . 1303011200-1308011400EST
ROUTE .....
ExampleRoute
!FDC x/xxxx ZFW OK..ROUTE ZFW ZKC.
V140 SAYRE (SYO) VORTAC, OK TO TULSA (TUL) VORTAC, OK MEA 4300.1305041000-1306302359EST
SPECIAL ...
ExampleSpecial
!FDC x/xxxx PAJN SPECIAL JUNEAU INTERNATIONAL, JUNEAU, AK.
LDA-2 RWY 8 AMDT 9PROCEDURE TURN NA. 1305011200-1312111200EST
SECURITY ..
ExampleSecurity
!FDC ZZZ SECURITY ..SPECIAL NOTICE..THIS NOTICE IS TO EMPHASIZE THAT BEFORE
OPERATING IN OR ADJACENT TO IRANIAN AIRSPACE ALL U.S. AIRMEN AND OPERATORSSHOULD BE FAMILIAR WITH CURRENT CONDITIONS IN THE MIDDLE EAST. THE U.S. DEPART-MENT OF STATE HAS ISSUED A TRA VEL WARNING FOR IRAN ADVISING, IN PART, THAT THE U.S.GOVERNMENT DOES NOT CURRENTLY MAINTAIN DIPLOMATIC OR CONSULAR RELATIONSWITH THE ISLAMIC REPUBLIC OF IRAN. ANY U.S. OPERATOR PLANNING A FLIGHT THROUGH
IRANIAN AIRSPACE SHOULD PLAN IN ADV ANCE AND HA VE ALL CURRENT NOTAMS AND
AERONAUTICAL INFORMATION FOR ANY PLANNED FLIGHT 1311011200-1403301800EST
U........... Unverified Aeronautical Information
(for use only where authorized by Letter of Agreement )*
O.......... Other Aeronautical Information**
NOTE−
1.* Unverified Aeronautical Information can be movement ar ea or other information r eceived that meets NOTAM cr iteria
and has not been confirmed by the Airport Manager (AMGR) or their designee. If Flight Service is unable to contact airportmanagement, Flight Service must forward (U) NOTAM in formation to the United States NOTAM System (USNS).
Subsequent to USNS distribution of a (U) NOTAM, Flight Service will inform airport management of the action taken assoon as practical. Any such NOTAM will be prefaced with “(U)” as the keyword and followed by the appropriate keyword
contraction, following the location identifier.
2.** Other Aeronautical Information is that which is received from any authorized source that may be beneficial
to aircraft operations and does not meet defined NOTAM criteria. Any such NOTAM will be prefaced with “(O)” as the
keyword following the location identifier.
AIM 10/12/17
5−1−6 PreflightTBL 5−1−2
Contractions Commonly Found in NOTAMs
A
A B N .......... Aerodrome Beacon
A B V .......... Above
ACFT ......... Aircraft
A C T .......... Active
A D J .......... Adjacent
A G L .......... Above Ground Level
A L S .......... Approach Light System
A L T .......... Altitude
ALTN/ALTNLY . Alternate/Alternately
AMDT ........ Amendment
APCH ......... Approach
ARFF ......... Aircraft Rescue & Fire Fighting
ASDA ......... Accelerate Stop Distance Available
ASOS ......... Automated Surface Observing System
ASPH ......... Asphalt
A T C .......... Air Traffic Control
A T I S .......... Automated Terminal Information
Service
A V B L ......... Available
A W O S ........ Automatic Weather Observing System
A W S S......... Automated Weather Sensor System
A Z M.......... Azimuth
B
B T N .......... Between
C
C A T .......... Category
C H ........... Channel
C L ........... Centerline
CLSD ......... Closed
C O M ......... Communication
CONC ........ Concrete
CONT ......... Continue/Continuously
C T L .......... Control
D
D C T .......... Direct
D E P .......... Depart/Departure
D H ........... Decision Height
DLA/DLAD .... Delay/Delayed
D M E.......... Distance Measuring Equipment
DWPNT ....... Dew Point Temperature
E
E ............. East
E B ........... Eastbound
ELEV ......... Elevate/Elevation
E N G .......... Engine
E S T .......... Estimated
E X C .......... Except
F
F A C .......... Facility
F A F........... Final Approach Fix
F D C .......... Flight Data Center
FICON ........ Field Condition
FREQ ......... FrequencyF S S........... Flight Service Station
F T............ Feet
G
G C A .......... Ground Controlled Approach
G P ........... Glide Path
G P S .......... Global Positioning System
G R V L ......... Gravel
H
H E L .......... Helicopter
HIRL ......... High Intensity Runway Lights
H R ........... Hour
I
I D ............ Identify/Identifier
I F R ........... Instrument Flight Rules
I L S ........... Instrument Landing System
I M............ Inner Marker
I N ............ Inch/Inches
INOP ......... Inoperative
INST .......... Instrument
I N T........... Intersection
INTST ........ Intensity
L
L ............. Left
L B ........... Pound/Pounds
L D A .......... Landing Distance Available
L D G .......... Landing
LGT/LGTD .... Light/Lighted
LIRL .......... Low Intensity Runway Edge Lights
LNDG ........ Landing
L O C .......... Localizer
M
MALS ........ Medium Intensity Approach Lighting
System
MALSF ....... Medium Intensity Approach Lighting
System with Sequenced Flashers
MALSR ....... Medium Intensity Approach Lighting
System with Runway Alignment
Indicator Lights
M C A ......... Minimum Crossing Altitude
M D A ......... Minimum Descent Altitude
M E A.......... Minimum En Route Altitude
MIRL ......... Medium Intensity Runway Edge Lights
M K R ......... Marker
M M .......... Middle Marker
M N M ......... Minimum
M O A ......... Military Operations Area
MOCA ........ Minimum Obstruction Clearance
Altitude
M S G.......... Message
M S L .......... Mean Sea Level
M U ........... Designate a Friction Value RepresentingRunway Surface Conditions
N
N............. North
N D B .......... Nondirectional Radio Beacon
N E ........... Northeast
N M ........... Nautical Mile/s
AIM 10/12/17
5−1−7 PreflightN T A P ......... Notice To Airmen Publication
N W........... Northwest
O
OBSC ......... Obscured
O M ........... Outer Marker
O P R .......... Operate
ORIG ......... Original
P
P A P I .......... Precision Approach Path Indicator
P A R L ......... Parallel
P A X .......... Passenger/s
P C L .......... Pilot Controlled Lighting
PERM ......... Permanent
P J E ........... Parachute Jumping Activities
P L A .......... Practice Low Approach
P N ........... Prior Notice Required
P P R .......... Prior Permission Required
P T............ Procedure Turn
R
R A I........... Runway Alignment Indicator
R C L .......... Runway Centerline
RCLL ......... Runway Centerline Light
R E C .......... Receive/Receiver
RLLS ......... Runway Lead −in Light System
R N A V......... Area Navigation
R V R .......... Runway Visual Range
R V R M ........ RVR Midpoint
R V R R ......... RVR Rollout
R V R T ......... RVR Touchdown
R W Y ......... Runway
S
S ............. South
S A A .......... Special Activity Airspace
S E............ Southeast
S F C .......... Surface
SKED ......... Scheduled
S N ........... Snow
S R............ Sunrise
S S ............ Sunset
SSALF ........ Simplified Short Approach Lighting
System with Sequenced Flashers
SSALR ........ Simplified Short Approach Lighting
System with Runway Alignment
Indicator Lights
SSALS ........ Simplified Short Approach Lighting
System
S T A R ......... Standard Terminal Arrival
S T D .......... Standard
S W ........... Southwest
T
TACAN ....... Tactical Air Navigational Aid
T D Z .......... Touchdown Zone
TEMPO ....... Temporary
T F C .......... Traffic
T F R .......... Temporary Flight Restriction
T G L .......... Touch and Go LandingsT H R .......... Threshold
TKOF ......... Takeoff
T O D A......... Take−off Distance Available
T O R A......... Take−off Run Available
T W R.......... Aerodrome Control Tower
T W Y ......... Taxiway
U
U N L .......... Unlimited
UNREL ....... Unreliable
V
V A S I.......... Visual Approach Slope Indicator
V F R .......... Visual Flight Rules
V H F .......... Very High Frequency
V I S ........... Visibility
V M C ......... Visual Meteorological Conditions
VOLMET ...... Meteorlogical Information for Aircraft
in Flight
V O R .......... VHF Omni-Directional Radio Range
V O R T A C ...... VOR and TACAN (collocated)
V O T .......... VOR Test Facility
W
W ............ West
W A A S ........ Wide Area Augmentation System
WDI . . . Wind Direction Indicator
W P T .......... Waypoint
W X........... Weather
5−1−4. Flight Plan − VFR Flights
a.Except for operations in or penetrating a Coastal
or Domestic ADIZ or DEWIZ a flight plan is not
required for VFR flight.
REFERENCE −
AIM, Paragraph 5 −6−1 , National Security
b.It is strongly recommended that a flight plan
(for a VFR flight) be filed with an FAA FSS. This will
ensure that you receive VFR Search and Rescue
Protection.
REFERENCE −
AIM, Paragraph 6 −2−6 , Search and Rescue, gives the proper method of
filing a VFR flight plan.
c.To obtain maximum benefits from the flight
plan program, flight plans should be filed directlywith the nearest FSS. For your convenience, FSSs
provide aeronautical and meteorological briefings
while accepting flight plans. Radio may be used to
file if no other means are available.
NOTE−
Some states operate aeronautical communications facili-ties which will accept and forward flight plans to the FSS
for further handling.
d.When a “stopover” flight is anticipated, it is
recommended that a separate flight plan be filed for
AIM 10/12/17
5−1−8 Preflighteach “leg” when the stop is expected to be more than
1 hour duration.
e.Pilots are encouraged to give their departure
times directly to the FSS serving the departure airport
or as otherwise indicated by the FSS when the flight
plan is filed. This will ensure more efficient flight
plan service and permit the FSS to advise you of
significant changes in aeronautical facilities or
meteorological conditions. When a VFR flight planis filed, it will be held by the FSS until 1 hour after the
proposed departure time unless:
1.The actual departure time is received.
2.A revised proposed departure time is
received.
3.At a time of filing, the FSS is informed that
the proposed departure time will be met, but actualtime cannot be given because of inadequate
communications (assumed departures).
f.On pilot’s request, at a location having an active
tower, the aircraft identification will be forwarded by
the tower to the FSS for reporting the actual departure
time. This procedure should be avoided at busy
airports.
g.Although position reports are not required for
VFR flight plans, periodic reports to FAA FSSs alongthe route are good practice. Such contacts permit
significant information to be passed to the transiting
aircraft and also serve to check the progress of the
flight should it be necessary for any reason to locate
the aircraft.
EXAMPLE −
1.Bonanza 314K, over Kingfisher at (time), VFR flight
plan, Tulsa to Amarillo.
2.Cherokee 5133J, over Oklahoma City at (time),
Shreveport to Denver, no flight plan.
h.Pilots not operating on an IFR flight plan and
when in level cruising flight, are cautioned to
conform with VFR cruising altitudes appropriate to
the direction of flight.
i.When filing VFR flight plans, indicate aircraft
equipment capabilities by appending the appropriate
suffix to aircraft type in the same manner as that
prescribed for IFR flight.
REFERENCE −
AIM, Paragraph 5 −1−8 , Flight Plan − Domestic IFR Flights
j.Under some circumstances, ATC computer
tapes can be useful in constructing the radar historyof a downed or crashed aircraft. In each case,
knowledge of the aircraft’s transponder equipment is
necessary in determining whether or not suchcomputer tapes might prove effective.
AIM 10/12/17
5−1−9 PreflightFIG 5−1−1
FAA Flight Plan
Form 7233 −1 (8−82)
U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION (FAA USE ONLY)(FAA USE ONLY) PILOT BRIEFINGPILOT BRIEFING VNRVNR
STOPOVERSTOPOVERTIME STARTEDTIME STARTEDSPECIALIST
INITIALSSPECIALIST
INITIALS
1. TYPE1. TYPE
VFRVFR
IFRIFR
DVFRDVFR3. AIRCRAFT TYPE/
SPECIAL EQUIPMENT3. AIRCRAFT TYPE/
SPECIAL EQUIPMENT5. DEPARTURE POINT5. DEPARTURE POINT 6. DEPARTURE TIME6. DEPARTURE TIME
PROPOSED (Z)PROPOSED (Z) ACTUAL (Z)ACTUAL (Z)7. CRUISING
ALTITUDE7. CRUISING
ALTITUDE
8. ROUTE OF FLIGHT8. ROUTE OF FLIGHTKTSKTS
9. DESTINATION (Name of airport
and city)9. DESTINATION (Name of airport
and city)10. EST. TIME ENROUTE10. EST. TIME ENROUTE
HOURSHOURS
HOURSHOURSMINUTESMINUTES
MINUTESMINUTES11. REMARKS11. REMARKS
12. FUEL ON BOARD12. FUEL ON BOARD 13. ALTERNATE AIRPORT(S)13 . A L TE RNA TE A IRP ORT (S) 14. PILOT’S NAME, ADDRESS & TELEPHONE NUMBER & AIRCRAFT HOME BASE14. PILOT’S NAME, ADDRESS & TELEPHONE NUMBER & AIRCRAFT HOME BASE 15. NUMBER
ABOARD15. NUMBER
ABOARD
17. DESTINATION CONTACT/TELEPHONE (OPTIONAL)17. DESTINATION CONTACT/TELEPHONE (OPTIONAL)
16. COLOR OF AIRCRAFT16. COLOR OF AIRCRAFT
FAA Form 7233-1FAA Form 7233-1 (8-82)(8-82) CLOSE VFR FLIGHT PLAN WITH _________________ FSS ON ARRIVALCLOSE VFR FLIGHT PLAN WITH _________________ FSS ON ARRIVALFLIGHT PLANFLIGHT PLAN
CIVIL AIRCRAFT PILOTS, FAR 91 requires you file an IFR flight plan to operate under instrument flight rules in
controlled airspace. Failure to file could result in a civil penalty not to exceed $1,000 for each violation (Section 901 of th e
Federal Aviation Act of 1958, as amended). Filing of a VFR flight plan is recommended as a good operating practice. See alsoPart 99 for requirements concerning DVFR flight plans.2. AIRCRAFT
IDENTIFICATION2. AIRCRAFT
IDENTIFICATION4. TRUE
AIRSPEED4. TRUE
AIRSPEED
k.Flight Plan Form − (See FIG 5−1−1).
l. Explanation of VFR Flight Plan Items.
1. Block 1. Check the type flight plan. Check
both the VFR and IFR blocks if composite VFR/IFR.
2. Block 2. Enter your complete aircraft
identification including the prefix “N” if applicable.
3. Block 3. Enter the designator for the aircraft,
or if unknown, consult an FSS briefer.
4. Block 4. Enter your true airspeed (TAS).
5. Block 5. Enter the departure airport identifi-
er code, or if unknown, the name of the airport.
6. Block 6. Enter the proposed departure time
in Coordinated Universal Time (UTC) (Z). If
airborne, specify the actual or proposed departuretime as appropriate.
7. Block 7. Enter the appropriate VFR altitude
(to assist the briefer in providing weather and wind
information).8. Block 8. Define the route of flight by using
NA V AID identifier codes and airways.
9. Block 9. Enter the destination airport
identifier code, or if unknown, the airport name.
NOTE−
Include the city name (or even the state name) if needed for
clarity.
10. Block 10. Enter your estimated time
en route in hours and minutes.
11. Block 11. Enter only those remarks that
may aid in VFR search and rescue, such as plannedstops en route or student cross country, or remarks
pertinent to the clarification of other flight plan
information, such as the radiotelephony (call sign)associated with a designator filed in Block 2, if the
radiotelephony is new, has changed within the last 60
days, or is a special FAA-assigned temporaryradiotelephony. Items of a personal nature are not
accepted.
AIM 10/12/17
5−1−10 Preflight12. Block 12. Specify the fuel on board in
hours and minutes.
13. Block 13. Specify an alternate airport if
desired.
14. Block 14. Enter your complete name,
address, and telephone number. Enter sufficientinformation to identify home base, airport, or
operator.
NOTE−
This information is essential in the event of search andrescue operations.
15. Block 15. Enter total number of persons on
board (POB) including crew.
16. Block 16. Enter the predominant colors.
17. Block 17. Record the FSS name for closing
the flight plan. If the flight plan is closed with adifferent FSS or facility, state the recorded FSS name
that would normally have closed your flight plan.
NOTE−
1.Optional− record a destination telephone number to
assist search and rescue contact should you fail to report
or cancel your flight plan within 1/2 hour after yourestimated time of arrival (ETA).
2.The information transmitted to the destination FSS will
consist only of flight plan blocks 2, 3, 9, and 10. Estimatedtime en route (ETE) will be converted to the correct ETA.
5−1−5. Operational Information System
(OIS)
a.The FAA’s Air Traffic Control System
Command Center (ATCSCC) maintains a website
with near real−time National Airspace System (NAS)
status information. NAS operators are encouraged to
access the website at http://www.fly.faa.gov prior to
filing their flight plan.
b.The website consolidates information from
advisories. An advisory is a message that is
disseminated electronically by the ATCSCC thatcontains information pertinent to the NAS.
1.Advisories are normally issued for the
following items:
(a)Ground Stops.
(b)Ground Delay Programs.(c)Route Information.
(d)Plan of Operations.
(e)Facility Outages and Scheduled Facility
Outages.
(f)V olcanic Ash Activity Bulletins.
(g)Special Traffic Management Programs.
2.This list is not all −inclusive. Any time there
is information that may be beneficial to a largenumber of people, an advisory may be sent.
Additionally, there may be times when an advisory is
not sent due to workload or the short length of time ofthe activity.
3.Route information is available on the website
and in specific advisories. Some route information,
subject to the 56 −day publishing cycle, is located on
the “OIS” under “Products,” Route ManagementTool (RMT), and “What’s New” Playbook. The RMT
and Playbook contain routings for use by Air Traffic
and NAS operators when they are coordinated“real−time” and are then published in an ATCSCC
advisory.
4.Route advisories are identified by the word
“Route” in the header; the associated action is
required (RQD), recommended (RMD), planned(PLN), or for your information (FYI). Operators are
expected to file flight plans consistent with the Route
RQD advisories.
5.Electronic System Impact Reports are on the
intranet at http://www.atcscc.faa.gov/ois/ under“System Impact Reports.” This page lists scheduled
outages/events/projects that significantly impact
the NAS; for example, runway closures, air shows,and construction projects. Information includes
anticipated delays and traffic management initiat-
ives (TMI) that may be implemented.
5−1−6. Flight Plan − Defense VFR (DVFR)
Flights
VFR flights (except DOD or law enforcement flights)
into a Coastal or Domestic ADIZ/DEWIZ are
required to file DVFR flight plans for securitypurposes. Detailed ADIZ procedures are found in
Section 6, National Security and Interception Proce-
dures, of this chapter. (See 14 CFR Part 99.)
AIM 10/12/17
5−1−11 Preflight5−1−7. Composite Flight Plan (VFR/IFR
Flights)
a.Flight plans which specify VFR operation for
one portion of a flight, and IFR for another portion,
will be accepted by the FSS at the point of departure.
If VFR flight is conducted for the first portion of the
flight, pilots should report their departure time to the
FSS with whom the VFR/IFR flight plan was filed;and, subsequently, close the VFR portion and request
ATC clearance from the FSS nearest the point at
which change from VFR to IFR is proposed.
Regardless of the type facility you are communicat-
ing with (FSS, center, or tower), it is the pilot’sresponsibility to request that facility to “CLOSE VFR
FLIGHT PLAN.” The pilot must remain in VFR
weather conditions until operating in accordance with
the IFR clearance.
b.When a flight plan indicates IFR for the first
portion of flight and VFR for the latter portion, thepilot will normally be cleared to the point at which the
change is proposed. After reporting over the
clearance limit and not desiring further IFR
clearance, the pilot should advise ATC to cancel the
IFR portion of the flight plan. Then, the pilot shouldcontact the nearest FSS to activate the VFR portion of
the flight plan. If the pilot desires to continue the IFR
flight plan beyond the clearance limit, the pilot should
contact ATC at least 5 minutes prior to the clearance
limit and request further IFR clearance. If the
requested clearance is not received prior to reachingthe clearance limit fix, the pilot will be expected to
enter into a standard holding pattern on the radial or
course to the fix unless a holding pattern for theclearance limit fix is depicted on a U.S. Government
or commercially produced (meeting FAA require-
ments) low or high altitude enroute, area or STARchart. In this case the pilot will hold according to the
depicted pattern.
5−1−8. Flight Plan (FAA Form 7233 −1)−
Domestic IFR Flights
NOTE−
1.Procedures outlined in this section apply to operators
filing F AA Form 7233 −1 (Flight Plan) and to flights that
will be conducted entirely within U.S. domestic airspace.
2.Filers utilizing F AA Form 7233 −1 may not be eligible
for assignment of RNAV SIDs and STARs. Filers desiring
assignment of these pr ocedures should file using F AA Form7233−4 (International Flight Plan), as described in
paragraph 5 −1−9.
a. General
1.Prior to departure from within, or prior to
entering controlled airspace, a pilot must submit acomplete flight plan and receive an air traffic
clearance, if weather conditions are below VFR
minimums. Instrument flight plans may be submitted
to the nearest FSS or ATCT either in person or by
telephone (or by radio if no other means are
available). Pilots should file IFR flight plans at least30 minutes prior to estimated time of departure to
preclude possible delay in receiving a departure
clearance from ATC. In order to provide FAA traffic
management units strategic route planning capabili-
ties, nonscheduled operators conducting IFR
operations above FL 230 are requested to voluntarily
file IFR flight plans at least 4 hours prior to estimated
time of departure (ETD). To minimize your delay in
entering Class B, Class C, Class D, and Class Esurface areas at destination when IFR weather
conditions exist or are forecast at that airport, an IFR
flight plan should be filed before departure.
Otherwise, a 30 minute delay is not unusual in
receiving an ATC clearance because of time spent in
processing flight plan data. Traffic saturation
frequently prevents control personnel from accepting
flight plans by radio. In such cases, the pilot is advised
to contact the nearest FSS for the purpose of filing the
flight plan.
NOTE−
1.There are several methods of obtaining IFR clearances
at nontower, non −FSS, and outlying airports. The
procedure may vary due to geographical features, weather
conditions, and the complexity of the ATC system. To
determine the most effective means of receiving an IFR
clearance, pilots should ask the nearest FSS the mostappropriate means of obtaining the IFR clearance.
2.When requesting an IFR clearance, it is highly
recommended that the departure airport be identified by
stating the city name and state and/or the airport location
identifier in or der to clarify to ATC the exact location of the
intended airport of departure.
2.When filing an IFR flight plan, include as a
prefix to the aircraft type, the number of aircraft when
more than one and/or heavy aircraft indicator “H/” if
appropriate.
EXAMPLE −
H/DC10/A2/F15/A
AIM 10/12/17
5−1−12 Preflight3.When filing an IFR flight plan, identify the
equipment capability by adding a suffix, preceded by
a slant, to the AIRCRAFT TYPE, as shown in
TBL 5−1−3, Aircraft Suffixes.
NOTE−
1.ATC issues clearances based on filed suffixes. Pilots
should determine the appropriate suffix based upon
desired services and/or routing. For example, if a desiredroute/procedure requires GPS, a pilot should file /G evenif the aircraft also qualifies for other suffixes.
2.For procedures r equiring GPS, if the navigation system
does not automatically alert the flight crew of a loss of GPS,
the operator must develop pr ocedures to verify correct GPS
operation.
3.The suffix is not to be added to the air craft identification
or be transmitted by radio as part of the aircraftidentification.
4.It is recommended that pilots file the
maximum transponder or navigation capability of
their aircraft in the equipment suffix. This will
provide A TC with the necessary information to utilize
all facets of navigational equipment and transpondercapabilities available.
5.When filing an IFR flight plan via telephone
or radio, it is highly recommended that the departure
airport be clearly identified by stating the city name
and state and/or airport location identifier. With cell
phone use and flight service specialists covering
larger areas of the country, clearly identifying thedeparture airport can prevent confusing your airport
of departure with those of identical or similar names
in other states.
TBL 5−1−3
Aircraft Equipment Suffixes
Navigation Capability Transponder Capability Suffix
RVSM No GNSS, No RNA V Transponder with Mode C /W
RNA V , No GNSS Transponder with Mode C /Z
GNSS Transponder with Mode C /L
No RVSM
No DMENo Transponder /X
Transponder with no Mode C /T
Transponder with Mode C /U
DMENo Transponder /D
Transponder with no Mode C /B
Transponder with Mode C /A
TACANNo Transponder /M
Transponder with no Mode C /N
Transponder with Mode C /P
RNA V , no GNSSNo Transponder /Y
Transponder with no Mode C /C
Transponder with Mode C /I
GNSSNo Transponder /V
Transponder with no Mode C /S
Transponder with Mode C /G
AIM 10/12/17
5−1−13 Preflightb. Airways and Jet Routes Depiction on Flight
Plan
1.It is vitally important that the route of flight
be accurately and completely described in the flight
plan. To simplify definition of the proposed route,
and to facilitate ATC, pilots are requested to file via
airways or jet routes established for use at the altitude
or flight level planned.
2.If flight is to be conducted via designated
airways or jet routes, describe the route by indicating
the type and number designators of the airway(s) or
jet route(s) requested. If more than one airway or jetroute is to be used, clearly indicate points of
transition. If the transition is made at an unnamed
intersection, show the next succeeding NA V AID ornamed intersection on the intended route and the
complete route from that point. Reporting points may
be identified by using authorized name/code asdepicted on appropriate aeronautical charts. The
following two examples illustrate the need to specify
the transition point when two routes share more than
one transition fix.
EXAMPLE −
1.ALB J37 BUMPY J14 BHM
Spelled out: from Albany, New York, via Jet Route 37transitioning to Jet Route 14 at BUMPY intersection,
thence via Jet Route 14 to Birmingham, Alabama.
2.ALB J37 ENO J14 BHM
Spelled out: from Albany, New York, via Jet Route 37
transitioning to Jet Route 14 at Smyrna VORTAC (ENO)
thence via Jet Route 14 to Birmingham, Alabama.
3.The route of flight may also be described by
naming the reporting points or NA VAIDs over which
the flight will pass, provided the points named areestablished for use at the altitude or flight level
planned.
EXAMPLE −
BWI V44 SWANN V433 DQOSpelled out: from Baltimore-W ashington International, via
Victor 44 to Swann intersection, transitioning to Victor 433
at Swann, thence via Victor 433 to Dupont.
4.When the route of flight is defined by named
reporting points, whether alone or in combinationwith airways or jet routes, and the navigational aids
(VOR, VORTAC, TACAN, NDB) to be used for the
flight are a combination of different types of aids,enough information should be included to clearly
indicate the route requested.
EXAMPLE −
LAX J5 LKV J3 GEG YXC FL 330 J500 VLR J515 YWGSpelled out: from Los Angeles International via Jet Route 5
Lakeview, Jet Route 3 Spokane, direct Cranbrook, British
Columbia VOR/DME, Flight Level 330 Jet Route 500 toLangruth, Manitoba VORTAC, Jet Route 515 to W innepeg,
Manitoba.
5.When filing IFR, it is to the pilot’s advantage
to file a preferred route.
REFERENCE −
Preferred IFR Routes are descri bed and tabulated in the Chart
Supplement U.S.
6.ATC may issue a SID or a STAR, as
appropriate.
REFERENCE −
AIM, Paragraph 5 −2−8 , Instrument Departure Procedures (DP) −
Obstacle Departure Procedures (ODP) and Standard Instrument
Departures (SID)
AIM, Paragraph 5 −4−1 , Standard Terminal Arrival (STAR) Procedures
NOTE−
Pilots not desiring a SID or STAR should so indicate in the
remarks section of the flight plan as “no SID” or “no
STAR.”
c. Direct Flights
1.All or any portions of the route which will not
be flown on the radials or courses of establishedairways or routes, such as direct route flights, must be
defined by indicating the radio fixes over which the
flight will pass. Fixes selected to define the route
must be those over which the position of the aircraft
can be accurately determined. Such fixes automati-cally become compulsory reporting points for the
flight, unless advised otherwise by ATC. Only those
navigational aids established for use in a particularstructure; i.e., in the low or high structures, may be
used to define the en route phase of a direct flight
within that altitude structure.
2.The azimuth feature of VOR aids and that
azimuth and distance (DME) features of VORTAC
and TACAN aids are assigned certain frequencyprotected areas of airspace which are intended for
application to established airway and route use, and
to provide guidance for planning flights outside of
established airways or routes. These areas of airspace
are expressed in terms of cylindrical service volumesof specified dimensions called “class limits” or
“categories.”
REFERENCE −
AIM, Paragraph 1 −1−8 , Navigational Aid (NAVAID) Service Volumes
AIM 10/12/17
5−1−14 Preflight3.An operational service volume has been
established for each class in which adequate signal
coverage and frequency protection can be assured. To
facilitate use of VOR, VORTAC, or TACAN aids,
consistent with their operational service volumelimits, pilot use of such aids for defining a direct route
of flight in controlled airspace should not exceed the
following:
(a)Operations above FL 450 − Use aids not
more than 200 NM apart. These aids are depicted on
enroute high altitude charts.
(b)Operation off established routes from
18,000 feet MSL to FL 450 − Use aids not more than
260 NM apart. These aids are depicted on enroute
high altitude charts.
(c)Operation off established airways below
18,000 feet MSL − Use aids not more than 80 NM
apart. These aids are depicted on enroute low altitude
charts.
(d)Operation off established airways be-
tween 14,500 feet MSL and 17,999 feet MSL in the
conterminous U.S. − (H) facilities not more than
200 NM apart may be used.
4.Increasing use of self-contained airborne
navigational systems which do not rely on the
VOR/VORTAC/TACAN system has resulted in pilot
requests for direct routes which exceed NA V AID
service volume limits. These direct route requests
will be approved only in a radar environment, withapproval based on pilot responsibility for navigation
on the authorized direct route. Radar flight following
will be provided by ATC for ATC purposes.
5.At times, ATC will initiate a direct route in a
radar environment which exceeds NA V AID service
volume limits. In such cases ATC will provide radarmonitoring and navigational assistance as necessary.
6.Airway or jet route numbers, appropriate to
the stratum in which operation will be conducted,
may also be included to describe portions of the routeto be flown.
EXAMPLE −
MDW V262 BDF V10 BRL STJ SLN GCKSpelled out: from Chicago Midway Airport via Victor 262
to Bradford, Victor 10 to Burlington, Iowa, direct
St. Joseph, Missouri, direct Salina, Kansas, directGarden City, Kansas.NOTE−
When route of flight is described by radio fixes, the pilotwill be expected to fly a direct course between the pointsnamed.
7.Pilots are reminded that they are responsible
for adhering to obstruction clearance requirements onthose segments of direct routes that are outside of
controlled airspace. The MEAs and other altitudes
shown on low altitude IFR enroute charts pertain tothose route segments within controlled airspace, and
those altitudes may not meet obstruction clearance
criteria when operating off those routes.
d. Area Navigation (RNA V)
1.Random impromptu routes can only be
approved in a radar enviro nment. Factors that will be
considered by A TC in approving random impromptu
routes include the capability to provide radar
monitoring and compatibility with traffic volume and
flow. ATC will radar monitor each flight, however,
navigation on the random impromptu route is the
responsibility of the pilot.
2.Pilots of aircraft equipped with approved area
navigation equipment may file for RNA V routesthroughout the National Airspace System and may be
filed for in accordance with the following procedures.
(a)File airport-to-airport flight plans.
(b)File the appropriate RNA V capability
certification suffix in the flight plan.
(c)Plan the random route portion of the flight
plan to begin and end over appropriate arrival and
departure transition fixes or appropriate navigationaids for the altitude stratum within which the flight
will be conducted. The use of normal preferred
departure and arrival routes (DP/STAR), whereestablished, is recommended.
(d)File route structure transitions to and from
the random route portion of the flight.
(e)Define the random route by waypoints.
File route description waypoints by using degree-
distance fixes based on navigational aids which are
appropriate for the altitude stratum.
(f)File a minimum of one route description
waypoint for each ARTCC through whose area therandom route will be flown. These waypoints must be
located within 200 NM of the preceding center’s
boundary.
(g)File an additional route description
waypoint for each turnpoint in the route.
AIM 10/12/17
5−1−15 Preflight(h)Plan additional route description way-
points as required to ensure accurate navigation via
the filed route of flight. Navigation is the pilot’s
responsibility unless ATC assistance is requested.
(i)Plan the route of flight so as to avoid
prohibited and restricted airspace by 3 NM unless
permission has been obtained to operate in that
airspace and the appropriate ATC facilities areadvised.
NOTE−
To be approved for use in the National Airspace System,RNAV equipment must meet the appropriate system
availability, accuracy, and airworthiness standards. For
additional guidance on equipment requirements seeAC 20−130, Airworthiness Approval of Vertical Naviga-
tion (VNAV) Systems for use in the U.S. NAS and Alaska,or AC 20 −138, Airworthiness Approval of Global
Positioning System (GPS) Navigation Equipment for Use
as a VFR and IFR Supplemental Navigation System. Forairborne navigation database, see AC 90 −94, Guidelines
for Using GPS Equipment for IFR En Route and Terminal
Operations and for Nonprecision Instrument Approaches
in the U.S. National Airspace System, Section 2.
3.Pilots of aircraft equipped with latitude/
longitude coordinate navigation capability,
independent of VOR/TACAN references, may filefor random RNA V routes at and above FL 390 within
the conterminous U.S. using the following
procedures.
(a)File airport-to-airport flight plans prior to
departure.
(b)File the appropriate RNA V capability
certification suffix in the flight plan.
(c)Plan the random route portion of the flight
to begin and end over published departure/arrival
transition fixes or appropriate navigation aids for
airports without published transition procedures. The
use of preferred departure and arrival routes, such as
DP and STAR where established, is recommended.
(d)Plan the route of flight so as to avoid
prohibited and restricted airspace by 3 NM unless
permission has been obtained to operate in thatairspace and the appropriate ATC facility is advised.
(e)Define the route of flight after the
departure fix, including each intermediate fix(turnpoint) and the arrival fix for the destination
airport in terms of latitude/longitude coordinates
plotted to the nearest minute or in terms of NavigationReference System (NRS) waypoints. For latitude/
longitude filing the arrival fix must be identified by
both the latitude/longitude coordinates and a fix
identifier.
EXAMPLE −
MIA1 SRQ2 3407/106153 3407/11546 TNP4 LAX 5
1 Departure airport.
2 Departure fix.
3 Intermediate fix (turning point).
4 Arrival fix.
5 Destination airport.
or
ORD
1 IOW2 KP49G3 KD34U4 KL16O5 OAL6 MOD27
SFO8
1 Departure airport.
2 Transition fix (pitch point).
3 Minneapolis ARTCC waypoint.
4 Denver ARTCC Waypoint.
5 Los Angeles ARTCC waypoint (catch point).
6 Transition fix.
7 Arrival.
8 Destination airport.
(f)Record latitude/longitude coordinates by
four figures describing latitude in degrees and
minutes followed by a solidus and five figures
describing longitude in degrees and minutes.
(g)File at FL 390 or above for the random
RNA V portion of the flight.
(h)Fly all routes/route segments on Great
Circle tracks.
(i)Make any inflight requests for random
RNAV clearances or route amendments to an en routeATC facility.
e. Flight Plan Form − See FIG 5−1−2.
f. Explanation of IFR Flight Plan Items.
1. Block 1. Check the type flight plan. Check
both the VFR and IFR blocks if composite VFR/IFR.
2. Block 2. Enter your complete aircraft
identification including the prefix “N” if applicable.
3. Block 3. Enter the designator for the aircraft,
followed by a slant(/), and the transponder or DMEequipment code letter; e.g., C −182/U. Heavy aircraft,
add prefix “H” to aircraft type; example: H/DC10/U.
Consult an FSS briefer for any unknown elements.
AIM 10/12/17
5−1−16 PreflightFIG 5−1−2
FAA Flight Plan
Form 7233 −1 (8−82)
U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION (FAA USE ONLY)(FAA USE ONLY) PILOT BRIEFINGPILOT BRIEFING VNRVNR
STOPOVERSTOPOVERTIME STARTEDTIME STARTEDSPECIALIST
INITIALSSPECIALIST
INITIALS
1. TYPE1. TYPE
VFRVFR
IFRIFR
DVFRDVFR3. AIRCRAFT TYPE/
SPECIAL EQUIPMENT3. AIRCRAFT TYPE/
SPECIAL EQUIPMENT5. DEPARTURE POINT5. DEPARTURE POINT 6. DEPARTURE TIME6. DEPARTURE TIME
PROPOSED (Z)PROPOSED (Z) ACTUAL (Z)ACTUAL (Z)7. CRUISING
ALTITUDE7. CRUISING
ALTITUDE
8. ROUTE OF FLIGHT8. ROUTE OF FLIGHTKTSKTS
9. DESTINATION (Name of airport
and city)9. DESTINATION (Name of airport
and city)10. EST. TIME ENROUTE10. EST. TIME ENROUTE
HOURSHOURS
HOURSHOURSMINUTESMINUTES
MINUTESMINUTES11. REMARKS11. REMARKS
12. FUEL ON BOARD12. FUEL ON BOARD 13. ALTERNATE AIRPORT(S)13. ALTERNATE AIRPORT(S) 14. PILOT’S NAME, ADDRESS & TELEPHONE NUMBER & AIRCRAFT HOME BASE14. PILOT’S NAME, ADDRESS & TELEPHONE NUMBER & AIRCRAFT HOME BASE 15. NUMBER
ABOARD15. NUMBER
ABOARD
17. DESTINATION CONTACT/TELEPHONE (OPTIONAL)1 7. DESTINATION CONTACT/TELEPHONE (OPTIONAL)
16. COLOR OF AIRCRAFT16. COLOR OF AIRCRAFT
FAA Form 7233-1FAA Form 7233-1 (8-82)(8-82) CLOSE VFR FLIGHT PLAN WITH _________________ FSS ON ARRIVALCLOSE VFR FLIGHT PLAN WITH _________________ FSS ON ARRIVALFLIGHT PLANFLIGHT PLAN
CIVIL AIRCRAFT PILOTS, FAR 91 requires you file an IFR flight plan to operate under instrument flight rules in
controlled airspace. Failure to file could result in a civil penalty not to exceed $1,000 for each violation (Section 901 of th e
Federal Aviation Act of 1958, as amended). Filing of a VFR flight plan is recommended as a good operating practice. See alsoPart 99 for requirements concerning DVFR flight plans.2. AIRCRAFT
IDENTIFICATION2. AIRCRAFT
IDENTIFICATION4. TRUE
AIRSPEED4. TRUE
AIRSPEED
4. Block 4. Enter your computed true airspeed
(TAS).
NOTE−
If the average TAS changes plus or minus 5 percent or10 knots, whichever is greater, advise ATC.
5. Block 5. Enter the departure airport identifi-
er code (or the airport name, city and state, if the
identifier is unknown).
NOTE−
Use of identifier codes will expedite the processing of yourflight plan.
6. Block 6. Enter the proposed departure time in
Coordinated Universal Time (UTC) (Z). If airborne,
specify the actual or proposed departure time as
appropriate.
7. Block 7. Enter the requested en route altitude
or flight level.NOTE−
Enter only the initial r equested altitude in this block. When
more than one IFR altitude or flight level is desired alongthe route of flight, it is best to make a subsequent request
direct to the controller.
8. Block 8. Define the route of flight by using
NA V AID identifier codes (or names if the code is
unknown), airways, jet routes, and waypoints (for
RNA V).
NOTE−
Use NAVAIDs or waypoints to define direct routes and
radials/bearings to define other unpublished routes.
9. Block 9. Enter the destination airport
identifier code (or name if the identifier is unknown).
10. Block 10. Enter your estimated time en
route based on latest forecast winds.
AIM 10/12/17
5−1−17 Preflight11. Block 11. Enter only those remarks pertin-
ent to ATC or to the clarification of other flight plan
information, such as the appropriate radiotelephony
(call sign) associated with the FAA-assigned
three-letter company designator filed in Block 2, ifthe radiotelephony is new or has changed within the
last 60 days. In cases where there is no three-letter
designator but only an assigned radiotelephony or an
assigned three-letter designator is used in a medical
emergency, the radiotelephony must be included in
the remarks field. Items of a personal nature are notaccepted.
NOTE−
1.The pilot is responsible for knowing when it is
appropriate to file the radiotelephony in remarks under the
60-day rule or when using F AA special radiotelephonyassignments.
2.“DVRSN” should be placed in Block 11 only if the
pilot/company is requesting priority handling to their
original destination from ATC as a result of a diversion as
defined in the Pilot/Controller Glossary.
3.Do not assume that remarks will be automatically
transmitted to every controller. Specific ATC or en routerequests should be made directly to the appropriate
controller.
12. Block 12. Specify the fuel on board,
computed from the departure point.
13. Block 13. Specify an alternate airport if
desired or required, but do not include routing to the
alternate airport.
14. Block 14. Enter the complete name,
address, and telephone number of pilot-in-command,
or in the case of a formation flight, the formation
commander. Enter sufficient information to identifyhome base, airport, or operator.
NOTE−
This information would be essential in the event of searchand rescue operation.
15. Block 15. Enter the total number of persons
on board including crew.
16. Block 16. Enter the predominant colors.
NOTE−
Close IFR flight plans with tower, approach control, or
ARTCC, or if unable, with FSS. When landing at an airport
with a functioning control tower, IFR flight plans areautomatically canceled.g.The information transmitted to the ARTCC for
IFR flight plans will consist of only flight plan
blocks 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11.
h.A description of the International Flight Plan
Form is contained in the International Flight
Information Manual (IFIM).
5−1−9. International Flight Plan (FAA Form
7233−4)− IFR Flights (For Domestic or
International Flights)
a. General
Use of FAA Form 7233 −4 is:
1.Mandatory for assignment of RNA V SIDs
and STARs or other PBN routing,
2.Mandatory for all IFR flights that will depart
U.S. domestic airspace, and
3.Recommended for domestic IFR flights.
NOTE−
1.An abbreviated description of F AA Form 7233 −4
(International Flight Plan) may be found in this section. A
detailed description of F AA Form 7233 −4 may be found on
the F AA website at:http://www.faa.gov/about/office_org/
headquarters_offices/ato/ser vice_units/enroute/flight_pl
an_filing/
2.Filers utilizing F AA Form 7233 −1 (Flight Plan) may not
be eligible for assignment of RNAV SIDs and ST ARs. Filers
desiring assignment of these procedures should file usingFAA Form 7233 −4, as described in this section.
3.When filing an IFR flight plan using F AA Form 7233 −4,
it is recommended that filers include all operable
navigation, communication, and surveillance equipmentcapabilities by adding appr opriate equipment qualifiers as
shown in Tables 5 −1−3 and 5−1−4. These equipment
qualifiers should be filed in Item 10 of F AA Form 7233 −4.
4.ATC issues clearances based on aircraft capabilities
filed in Items 10 and 18 of F AA Form 7233 −4. Operators
should file all capabilities for which the aircraft and crew
is certified, capable, and authorized. PBN/ capability
should be filed as per paragraph 5-1-9 b 8 Items 18 (c) and
(d).
b. Explanation of Items Filed in FAA Form
7233−4
Procedures and other information provided in this
section are designed to assist operators using FAAForm 7233 −4 to file IFR flight plans for flights that
will be conducted entirely within U.S. domestic
airspace. Requirements and procedures for operating
AIM 10/12/17
5−1−18 Preflightoutside U.S. domestic airspace may vary signific-
antly from country to country. It is, therefore,
recommended that operators planning flights out-
side U.S. domestic airspace become familiar with
applicable international documents, includingAeronautical Information Publications (AIP); Inter-
national Flight Information Manuals (IFIM); and
ICAO Document 4444, Procedures for Air Naviga-tion Services/Air Traffic Management, Appendix 2.
NOTE−
F AA Form 7233 −4 is shown in FIG 5−1−3. The filer is
normally responsible for providing the informationrequired in Items 3 through 19.
1. Item 7. Aircraft Identification. Insert the
full registration number of the aircraft, or theapproved FAA/ICAO company or organizational
designator, followed by the flight number.
EXAMPLE −
N235RA, AAL3342, BONGO33
NOTE−
Callsigns filed in this item must begin with a letter followed
by 1−6 additional alphanumeric characters.
2. Item 8. Flight Rules and Type of Flight.
(a) Flight Rules. Insert the character “I” to
indicate IFR
(b) Type of Flight. Insert one of the
following letters to denote the type of flight:
(1) S if scheduled air service
(2) N if non−scheduled air transport
operation
(3) G if general aviation
(4) M if military
(5) X if other than any of the defined
categories above.
NOTE−
Type of flight is optional for flights that will be conductedentirely within U.S. domestic airspace.3. Item 9. Number, Type of Aircraft, and
Wake Turbulence Category.
(a) Number. Insert the number of aircraft, if
more than 1 (maximum 99).
(b) Type of Aircraft.
(1)Insert the appropriate designator as
specified in ICAO Doc 8643, Aircraft Type
Designators;
(2)Or, if no such designator has been
assigned, or in the case of formation flights consisting
of more than one type;
(3)Insert ZZZZ, and specify in Item 18, the
(numbers and) type(s) of aircraft preceded by TYP/.
(c) Wake Turbulence Category. Insert an
oblique stroke followed by one of the following
letters to indicate the wake turbulence category ofthe aircraft:
(1)H — HEA VY , to indicate an aircraft
type with a maximum certificated takeoff weight of
300,000 pounds (136 000 kg), or more;
(2)M — MEDIUM, to indicate an aircraft
type with a maximum certificated takeoff weight of
less than 300,000 pounds (136,000 kg), but more than
15,500 pounds (7,000 kg);
(3)L — LIGHT, to indicate an aircraft type
with a maximum certificated takeoff weight of15,500 pounds (7,000 kg) or less.
4. Item 10. Equipment
AIM 10/12/17
5−1−19 PreflightFIG 5−1−3
FAA International Flight Plan Form 7233 −4 (9−06)
AIM 10/12/17
5−1−20 Preflight
AIM 10/12/17
5−1−21 PreflightTBL 5−1−4
Aircraft COM, NA V , and Approach Equipment Qualifiers
INSERT one letter as follows:
N if no COM/NA V/approach aid equipment for the route to be flown is carried, or the equipment
is unserviceable,
(OR)
S if standard COM/NA V/approach aid equipment for the route to be flown is carried and
serviceable (see Note 1),
(AND/OR)
INSERT one or more of the following letters to indicate the COM/NA V/approach aid equipment available
and serviceable:
NOTE−
The capabilities described below comprise the following elements: a. Presence of relevant serviceable equipment on board the aircraft.
b. Equipment and capabilities commensurate with flight crew qualifications.
c. Where applicable, authorization from the appropriate authority.
A GBAS landing system J6 CPDLC FANS 1/A SATCOM (MTSAT)
B LPV (APV with SBAS) J7 CPDLC FANS 1/A SATCOM (Iridium)
C LORAN C L ILS
D DME M1 ATC RTF SATCOM (INMARSAT)
E1 FMC WPR ACARS M2 ATC RTF (MTSAT)
E2 D-FIS ACARS M3 ATC RTF (Iridium)
E3 PDC ACARS O VOR
F ADF P1−
P9Reserved for RCP
G (GNSS) – see Note 2 R PBN approved - see Note 4
H HF RTF T TACAN
I Inertial navigation U UHF RTF
J1 CPDLC ATN VDL Mode 2 − see Note 3 V VHF RTF
J2 CPDLC FANS 1/A HFDL W RVSM approved
J3 CPDLC FANS 1/A VDL Mode 4 X MNPS approved/North Atlantic (NAT) High Level Airspace
(HLA) approved
J4 CPDLC FANS 1/A VDL Mode 2 Y VHF with 8.33 kHz channel spacing capability
J5 CPDLC FANS 1/A SATCOM (INMARSAT) Z Other equipment carried or other capabilities - see Note 5
NOTE−
1.If the letter S is used, standard equipment is considered to be VHF RTF , VOR, and ILS within U.S. domestic airspace.
2.If the letter G is used, the types of external GNSS augmentation, if any, are specified in Item 18 following the indicator
NAV/ and separated by a space.
3.See RTCA/EUROCAE Interoperability Requirements Standard For ATN Baseline 1 (ATN B1 INTEROP Standard –
DO-280B/ED-110B) for data link services air traffic control clearance and information/air traffic control communications
management/air traffic control microphone check.
4.If the letter R is used, the performance −based navigation levels that ar e authorized must be specified in Item 18 following
the indicator PBN/. For further details, see Paragraph 5 −1−9 b 8, Item 18 (c) and (d).
5.If the letter Z is used, specify in Item 18 the other equipment carried, preceded by COM/, DAT/, and/or NAV/, as
appropriate.
6.Information on navigation capability is provided to ATC for clearance and routing purposes.
AIM 10/12/17
5−1−22 PreflightTBL 5−1−5
Aircraft Surveillance Equipment, Including Designators for Transponder, ADS −B, ADS−C, and Capabilities
INSERT N if no surveillance equipment for the route to be flown is carried, or the equipment is unserviceable,
OR
INSERT one or more of the following descriptors, to a maximum of 20 characters, to describe the serviceable surveillance equip-
ment and/or capabilities on board:
SSR Modes A and C
A Transponder - Mode A (4 digits – 4096 codes)
C Transponder - Mode A (4 digits – 4096 codes) and Mode C
SSR Mode S
E Transponder - Mode S, including aircraft identification, pressure-altitude and extended squitter (ADS-B) capability
H Transponder - Mode S, including aircraft identification, pressure-altitude and enhanced surveillance capability
I Transponder - Mode S, including aircraft identification, but no pressure-altitude capability
L Transponder - Mode S, including aircraft identification, pressure-altitude, extended squitter (ADS B) and enhanced surveil-
lance capability
P Transponder - Mode S, including pressure-altitude, but no aircraft identification capability
S Transponder - Mode S, including both pressure-altitude and aircraft identification capability
X Transponder - Mode S with neither aircraft identification nor pressure-altitude capability
NOTE−
Enhanced surveillance capability is the ability of the aircraft to down-link aircraft derived data via a Mode S transponder.
Followed by one or more of the following codes if the aircraft has ADS-B capability:
B1 ADS-B with dedicated 1090 MHz ADS-B “out” capability
B2 ADS-B with dedicated 1090 MHz ADS-B “out” and “in” capability
U1 ADS-B “out” capability using UAT
U2 ADS-B “out” and “in” capability using UAT
V1 ADS-B “out” capability using VDL Mode 4
V2 ADS-B “out” and “in” capability using VDL Mode 4
NOTE−
File no more than one code for each type of capability; for example, file B1 or B2,but not both.
Followed by one or more of the following codes if the aircraft has ADS-C capability:
D1 ADS-C with FANS 1/A capabilities
G1 ADS-C with ATN capabilities
EXAMPLE −
1.SDGW/SB1U1 {VOR, ILS, VHF , DME, GNSS, RVSM, Mode S transponder, ADS-B 1090 Extended Squitter out, ADS-B
UAT out}
2.S/C {VOR, ILS, VHF , Mode C transponder}
AIM 10/12/17
5−1−23 Preflight5. Item 13. Departure Aerodrome/Time
(a)Insert the ICAO four −letter location
indicator of the departure aerodrome, or
NOTE−
ICAO location indicators must consist of 4 letters. Airport
identifiers such as 5IA7, 39LL and Z40 are not in ICAOstandard format.
(b)If no four −letter location indicator has
been assigned to the departure aerodrome, insert
ZZZZ and specify the non −ICAO location identifier,
or fix/radial/distance from a nearby navaid, followedby the name of the aerodrome, in Item 18, following
characters DEP/,
(c)Then, without a space, insert the estimated
off−block time.
EXAMPLE −
1.KSMF2215
2.ZZZZ0330
6. Item 15. Cruise Speed, Level and Route
(a)Cruise Speed (maximum 5 characters).
Insert the true airspeed for the first or the wholecruising portion of the flight, in terms of knots,
expressed as N followed by 4 digits (e.g. N0485), or
Mach number to the nearest hundredth of unit Mach,
expressed as M followed by 3 digits (for example,
M082).
(b)Cruising level (maximum 5 characters).
Insert the planned cruising level for the first or thewhole portion of the route to be flown, in terms of
flight level, expressed as F followed by 3 figures (for
example, F180; F330), or altitude in hundreds of feet,
expressed as A followed by 3 figures (for example,
A040; A170).
(c)Route. Insert the requested route of flight
in accordance with guidance below.
NOTE−
Speed and/or altitude changes en route will be accepted by
F AA computer systems, but will not be processed orforwarded to controllers. Pilots are expected to maintainthe last assigned altitude and request revised altitude
clearances directly from ATC.
(d)Insert the desired route of flight using a
combination of published routes and/or fixes in the
following formats:(1)Consecutive fixes, navaids and waypo-
ints should be separated by the characters “DCT”,
meaning direct.
EXAMPLE −
FLACK DCT IRW DCT IRW125023
NOTE−
IRW125023 identifies the fix located on the Will RogersVORTAC 125 radial at 23 DME.
(2)Combinations of published routes, and
fixes, navaids or waypoints sho uld be separated by a
single space.
EXAMPLE −
WORTH5 MQP V66 ABI V385
(3)Although it is recommended that filed
airway junctions be identified using a named junction
fix when possible, there may be cases where it isnecessary to file junctioning airways without a named
fix. In these cases, separate consecutive airways with
a space.
EXAMPLE −
V325 V49
NOTE−
This method of filing an airway junction may result in aprocessing ambiguity. This might cause the flight plan to be
rejected in some cases.
7. Item 16. Destination Aerodrome, Total
EET, Alternate and 2nd Alternate Aerodrome
(a)Destination Aerodrome and Total Estim-
ated Elapsed Time (EET).
(1)Insert the ICAO four −letter location
identifier for the destination aerodrome; or, if no
ICAO location identifier has been assigned,
(Location identifiers, such as WY66, A08, and 5B1,
are not an ICAO standard format),
(2)Insert ZZZZ and specify the non −ICAO
location identifier, or fix/radial/distance from a
nearby navaid, followed the name of the aerodrome,
in Item 18, following characters DEST/,
(3)Then, without a space, insert the total
estimated time en route to the destination.
EXAMPLE −
1.KOKC0200
2.ZZZZ0330
(b)Alternate and 2nd Alternate Aerodrome
(Optional).
(1)Following the intended destination,
insert the ICAO four −letter location identifier(s) of
AIM 10/12/17
5−1−24 Preflightalternate aerodromes; or, if no location identifier(s)
have been assigned;
(2)Insert ZZZZ and specify the name of the
aerodrome in Item 18, following the characters
ALTN/.
EXAMPLE −
1.KDFW0234 KPWA
2.KBOS0304 ZZZZ
NOTE−
Although alternate airport information filed in an FPL will
be accepted by air traffic computer systems, it will not bepresented to contr ollers. If diversion to an alternate airport
becomes necessary, pilots are expected to notify ATC and
request an amended clearance.
8. Item 18. Other Information
(a)Insert 0 (zero) if no other information; or,
any other necessary information in the sequence
shown below, in the form of the appropriate indicator
followed by an oblique stroke and the information to
be recorded:
NOTE−
1.Operators are warned that the use of indicators not
included in the pr ovisions may r esult in data being r ejected,
processed incorrectly, or lost.
2.Hyphens “-” or oblique strokes “/” should only be used
as described.
3.Avoid use of any other special characters in Field 18
information- use only letters and numbers.
4.An indicator without any associated information will
result in flight plan rejection.
(b)STS/ Reason for special handling by ATS
as follows:
(1)ALTRV: For a flight operated in
accordance with an altitude reservation.
(2)ATFMX: For a flight approved for
exemption from ATFM measures by the appropriateATS authority.
(3)FFR: Fire-fighting.
(4)FLTCK: Flight check for calibration of
navaids.
(5)HAZMAT: For a flight carrying hazard-
ous material.
(6)HEAD: A flight with Head of State
status.(7)HOSP: For a medical flight declared by
medical authorities.
(8)HUM: For a flight operating on a
humanitarian mission.
(9)MARSA: For a flight for which a
military entity assumes responsibility for separation
of military aircraft.
(10) MEDEV AC: For a life critical medical
emergency evacuation.
(11) NONRVSM: For a non-RVSM
capable flight intending to operate in RVSM airspace.
(12) SAR: For a flight engaged in a search
and rescue mission.
(13) STATE: For a flight engaged in
military, customs, or police services.
NOTE−
Other reasons for special handling by ATS are denoted
under the designator RMK/.
(c)PBN/ Indication of RNA V and/or RNP
capabilities. Include as many of the descriptors below
as apply to the flight, up to a maximum of 8 entries;that is a total of not more than 16 characters.
TBL 5−1−6
PBN/RNA V Specifications
PBN/ RNA V SPECIFICATIONS
A1 RNA V 10 (RNP 10)
B1 RNA V 5 all permitted sensors
B2 RNA V 5 GNSS
B3 RNA V 5 DME/DME
B4 RNA V 5 VOR/DME
B5 RNA V 5 INS or IRS
B6 RNA V 5 LORAN C
C1 RNA V 2 all permitted sensors
C2 RNA V 2 GNSS
C3 RNA V 2 DME/DME
C4 RNA V 2 DME/DME/IRU
D1 RNA V 1 all permitted sensors
D2 RNA V 1 GNSS
D3 RNA V 1 DME/DME
D4 RNA V 1 DME/DME/IRU
AIM 10/12/17
5−1−25 PreflightRNP SPECIFICATIONS
L1 RNP 4
O1 Basic RNP 1 all permitted sensors
O2 Basic RNP 1 GNSS
O3 Basic RNP 1 DME/DME
O4 Basic RNP 1 DME/DME/IRU
S1 RNP APCH
S2 RNP APCH with BARO-VNA V
T1 RNP AR APCH with RF
(special authorization required)
T2 RNP AR APCH without RF(special authorization required)
NOTE−
Combinations of alphanumeric characters not indicatedabove are reserved.
(d)NA V/ Significant data related to naviga-
tion equipment, other than as specified in PBN/.
(1)When Performance Based Navigation
Capability has been filed in PBN/, if PBN routing is
desired for only some segment(s) of the flight thenthat information can be conveyed by inserting the
character “Z” in Item 10 and “NA V/RNV” in field 18
followed by the appropriate RNA V accuracy value(s)
per the following:
[a]To be assigned an RNA V 1 SID,
insert the characters “D1”.
[b]To be assigned an RNA V 1 STAR,
insert the characters “A1”.
[c]To be assigned en route extensions
and/or RNA V PTP, insert the characters “E2”.
[d]To prevent assignment of an RNA V
route or procedure, insert a numeric value of “0” for
the segment of the flight. Alternatively, you may
simply remove the segment of the flight indicator and
numeric value from the character string.
EXAMPLE −
1.NAV/RNVD1 or NAV/RNVD1E0A0 (Same meaning)
2.NAV/RNVA1 or NAV/RNVD0E0A1 (Same meaning)
3.NAV/RNVE2 or NAV/RNVD0E2A0 (Same meaning)
4. NAV/RNVD1A1 or NAV/RNVD1E0A1 (Same meaning)5.NAV/RNVD1E2A1
NOTE−
1.Route assignments are predicated on NAV/ data over
PBN/ data in ERAS.
2.Aircraft certification requirements for RNAV opera-
tions within U.S. airspace are defined in AC 90-45A,
Approval of Area Navigation Systems for Use in the U.S.
National Airspace System, and AC 90 −100A, U.S.
Terminal and En Route Area Navigation (RNAV)Operations, as amended.
(2)Operators should file their maximum
capabilities in order to qualify for the most advanced
procedures.
(e)COM/ Indicate communications capabil-
ities not specified in Item 10a, when requested by an
air navigation service provider.
(f)DAT/ Indicate data applications or capab-
ilities not specified in Item 10a, when requested by an
Air Navigation Service Provider.
(g)SUR/ Indicate surveillance capabilities
not specified in Item 10b, when requested by an Air
Navigation Service Provider. If ADS-B capability
filed in Item 10 is compliant with RTCA DO-260B,include the item “260B” in SUR/. If ADS-B
capability filed in Item 10 is compliant with RTCA
DO-282B, include the item “282B” in SUR/.
EXAMPLE −
1.SUR/260B
2.SUR/260B 282B
(h)DEP/ Insert the non −ICAO identifier, or
fix/radial/distance from navaid, or latitude/longitude,
if ZZZZ is inserted in Item 13. Optionally, append the
name of the departure point.
EXAMPLE −
1.DEP/T23 ALBANY MUNI
2.DEP/T23
3.DEP/UKW197011 TICK HOLLR RANCH
4.DEP/4620N07805W
(i)DEST/ Insert the non−ICAO identifier, or
fix/radial/distance from navaid, or latitude/longitude,
if ZZZZ is inserted in Item 16. Optionally, append the
name of the destination point.
EXAMPLE −
1.DEST/T23 ALBANY MUNI
2.DEST/PIE335033 LEXI DUNES
3.DEST/4620N07805W
AIM 10/12/17
5−1−26 Preflight(j)DOF/ The date of flight departure in a six
figure format (YYMMDD, where YY equals the
year, MM equals the month, and DD equals the day).
The FAA will not accept flight plans filed with Date
of Flight resulting in more than a day in advance.
(k)REG/ The registration markings of the
aircraft, if different from the aircraft identification in
Item 7. Note that the FAA uses this information inmonitoring of RVSM and ADS-B performance.
(l)EET/ Significant points or FIR boundary
designators and accumulated estimated elapsed times
to such points or FIR boundaries.
EXAMPLE −
EET/KZLA0745 KZAB0830
(m) SEL/ SELCAL code.
(n)TYP/ Insert the type of aircraft if ZZZZ
was entered in Item 9. If necessary, insert the numberand type(s) of aircraft in a formation.
EXAMPLE −
1.TYP/Homebuilt
2.TYP/2 P51 B17 B24
(o)CODE/ Aircraft address (expressed in
the form of an alphanumerical code of six
hexadecimal characters) when required by the
appropriate ATS authority. Include CODE/ when
ADS-B capability is filed in Item 10.
EXAMPLE −
“F00001” is the lowest aircraft address contained in thespecific block administered by ICAO.
(p)DLE/ En route delay or holding, insert
the significant point(s) on the route where a delay isplanned to occur, followed by the length of delay
using four figure time in hours and minutes (hhmm).
EXAMPLE −
DLE/MDG0030
(q)OPR/ Name of the operator, if not
obvious from the aircraft identification in Item 7.
(r)ORGN/ The originator’s 8-letter AFTN
address or other appropriate contact details, in cases
where the originator of the flight plan may not bereadily identified, as required by the appropriate A TS
authority. The FAA does not require ORGN/
information.NOTE−
In some areas, flight plan reception centers may insert theORGN/ identifier and originator’ s AFTN addressautomatically.
(s)PER/ Aircraft performance data, indic-
ated by a single letter as specified in the Procedures
for Air Navigation Services - Aircraft Operations
(PANS-OPS, Doc 8168), V olume I - FlightProcedures, if so prescribed by the appropriate ATS
authority. Note that the FAA does not require PER/
information.
(t)ALTN/ Name of destination alternate
aerodrome(s), if ZZZZ is inserted in Item 16.
EXAMPLE −
1.ALTN/F35 POSSUM KINGDOM
2.ALTN/TCC233016 LAZY S RANCH
(u)RALT/ ICAO 4-letter indicator(s) for
en-route alternate(s), as specified in Doc 7910,
Location Indicators, or name(s) of en-route alternate
aerodrome(s), if no indicator is allocated. Foraerodromes not listed in the relevant Aeronautical
Information Publication, indicate location in LAT/
LONG or bearing and distance from the nearestsignificant point, as described in DEP/ above.
(v)TALT/ ICAO 4-letter indicator(s) for
take-off alternate, as specified in Doc 7910, Location
Indicators, or name of take-off alternate aerodrome,
if no indicator is allocated. For aerodromes not listed
in the relevant Aeronautical Information Publication,
indicate location in LAT/LONG or bearing and
distance from the nearest significant point, as
described in DEP/ above.
(w) RIF/ The route details to the revised
destination aerodrome, followed by the ICAO
four-letter location indicator of the aerodrome. Therevised route is subject to reclearance in flight.
EXAMPLE −
1.RIF/DTA HEC KLAX
2.RIF/ESP G94 CLA YPPH
(x)RMK/ Any other plain −language re-
marks when required by the ATC or deemednecessary.
EXAMPLE −
1.RMK/NRP
2.RMK/DRVSN
(y)RVR/ The minimum RVR requirement of
the flight in meters. This item is defined by
AIM 10/12/17
5−1−27 PreflightEurocontrol, not ICAO. The FAA does not require or
use this item, but will accept it in a flight plan.
NOTE−
This provision is detailed in the European RegionalSupplementary Procedures (EUR SUPPs, Doc 7030),
Chapter 2.
(z)RFP/ Q followed by a digit to indicate the
sequence of the replacement flight plan being
submitted. This item is defined by Eurocontrol, not
ICAO. The FAA will not use this item, but will accept
it in a flight plan.
NOTE−
This provision is detailed in the European Regional
Supplementary Procedures (EUR SUPPs, Doc 7030),chapter 2.
9. Item 19. Supplementary Information
NOTE−
Item 19 data must be included when completing F AA Form
7233−4. This information will be retained by the
facility/organization that transmits the flight plan to AirTraffic Control (ATC), for Search and Rescue purposes, but
it will not be transmitted to ATC as part of the FPL.
(a)E/ (ENDURANCE). Insert 4 −digits group
giving the fuel endurance in hours and minutes.
(b)P/ (PERSONS ON BOARD). Insert the
total number of persons (passengers and crew) onboard.
(c)Emergency and survival equipment
(1)R/ (RADIO).
[a]Cross out “UHF” if frequency 243.0
MHz is not available.
[b]Cross out “VHF” frequency 121.5
MHz is not available.
[c]Cross out “ELBA” if emergency
locator transmitter (ELT) is not available.
(2)S/ (SURVIV AL EQUIPMENT).
[a]Cross out “POLAR” if polar survival
equipment is not carried.
[b]Cross out “DESERT” if desert
survival equipment is not carried.
[c]Cross out “MARITIME” if maritime
survival equipment is not carried.
[d]Cross out J if “JUNGLE” survival
equipment is not carried.(3)J/ (JACKETS).
[a]Cross out “LIGHT” if life jackets are
not equipped with lights.
[b]Cross out “FLUORES” if life jackets
are not equipped with fluorescein.
[c]Cross out “UHF” or “VHF” or both as
in R/ above to indicate radio capability of jackets, ifany.
(4)D/ (DINGHIES).
[a]NUMBER. Cross out indicators
“NUMBER” and “CAPACITY” if no dinghies are
carried, or insert number of dinghies carried; and
[b]CAPACITY . Insert total capacity, in
persons, of all dinghies carried; and
[c]COVER. Cross out indicator
“COVER” if dinghies are not covered; and
[d]COLOR. Insert color of dinghies if
carried.
(5)A/ (AIRCRAFT COLOR AND
MARKINGS). Insert color of aircraft and significant
markings.
(6)N/ (REMARKS). Cross out indicator N
if no remarks, or indicate any other survival
equipment carried and any other remarks regardingsurvival equipment.
(7)C/ (PILOT). Insert name of pilot −in−
command.
5−1−10. IFR Operations to High Altitude
Destinations
a.Pilots planning IFR flights to airports located in
mountainous terrain are cautioned to consider thenecessity for an alternate airport even when the
forecast weather conditions would technically relieve
them from the requirement to file one.
REFERENCE −
14 CFR Section 91.167.
AIM, Paragraph 4 −1−19 , Tower En Route Control (TEC)
b.The FAA has identified three possible situations
where the failure to plan for an alternate airport when
flying IFR to such a destination airport could result in
a critical situation if the weather is less than forecast
and sufficient fuel is not available to proceed to asuitable airport.
1.An IFR flight to an airport where the
Minimum Descent Altitudes (MDAs) or landing
AIM 10/12/17
5−1−28 Preflightvisibility minimums for all instrument approaches
are higher than the forecast weather minimums
specified in 14 CFR Section 91.167(b). For example,
there are 3 high altitude airports in the U.S. with
approved instrument approach procedures where allof the MDAs are greater than 2,000 feet and/or the
landing visibility minimums are greater than 3 miles
(Bishop, California; South Lake Tahoe, California;and Aspen −Pitkin Co./Sardy Field, Colorado). In the
case of these airports, it is possible for a pilot to elect,
on the basis of forecasts, not to carry sufficient fuel to
get to an alternate when the ceiling and/or visibility
is actually lower than that necessary to complete the
approach.
2.A small number of other airports in
mountainous terrain have MDAs which are slightly(100 to 300 feet) below 2,000 feet AGL. In situations
where there is an option as to whether to plan for an
alternate, pilots should bear in mind that just a slight
worsening of the weather conditions from those
forecast could place the airport below the published
IFR landing minimums.
3.An IFR flight to an airport which requires
special equipment; i.e., DME, glide slope, etc., inorder to make the available approaches to the lowest
minimums. Pilots should be aware that all other
minimums on the approach charts may require
weather conditions better than those specified in
14 CFR Section 91.167(b). An inflight equipmentmalfunction could result in the inability to comply
with the published approach procedures or, again, in
the position of having the airport below the publishedIFR landing minimums for all remaining instrument
approach alternatives.
5−1−11. Flights Outside the U.S. and U.S.
Territories
a.When conducting flights, particularly extended
flights, outside the U.S. and its territories, full
account should be taken of the amount and quality of
air navigation services available in the airspace to betraversed. Every effort should be made to secure
information on the location and range of navigational
aids, availability of communications and meteoro-logical services, the provision of air traffic services,
including alerting service, and the existence of search
and rescue services.b.Pilots should remember that there is a need to
continuously guard the VHF emergency frequency
121.5 MHz when on long over-water flights, except
when communications on other VHF channels,
equipment limitations, or cockpit duties preventsimultaneous guarding of two channels. Guarding of
121.5 MHz is particularly critical when operating in
proximity to Flight Information Region (FIR)boundaries, for example, operations on Route R220
between Anchorage and Tokyo, since it serves to
facilitate communications with regard to aircraftwhich may experience in-flight emergencies, com-
munications, or navigational difficulties.
REFERENCE −
ICAO Annex 10, Vol II, Paras 5.2.2.1.1.1 and 5.2.2.1.1.2.
c.The filing of a flight plan, always good practice,
takes on added significance for extended flights
outside U.S. airspace and is, in fact, usually required
by the laws of the countries being visited or
overflown. It is also particularly important in the case
of such flights that pilots leave a complete itinerary
and schedule of the flight with someone directly
concerned and keep that person advised of the flight’s
progress. If serious doubt arises as to the safety of the
flight, that person should first contact the appropriate
FSS. Round Robin Flight Plans to Mexico are notaccepted.
d.All pilots should review the foreign airspace
and entry restrictions published in the IFIM during
the flight planning process. Foreign airspace
penetration without official authorization can involve
both danger to the aircraft and the imposition of
severe penalties and inconvenience to both passen-
gers and crew. A flight plan on file with ATCauthorities does not necessarily constitute the prior
permission required by certain other authorities. The
possibility of fatal consequences cannot be ignored in
some areas of the world.
e.Current NOTAMs for foreign locations must
also be reviewed. The publication Notices to Airmen,
Domestic/International, published biweekly, con-tains considerable information pertinent to foreign
flight. Current foreign NOTAMs are also available
from the U.S. International NOTAM Office inWashington, D.C., through any local FSS.
f.When customs notification is required, it is the
responsibility of the pilot to arrange for customs
notification in a timely manner. The following
guidelines are applicable:
AIM 10/12/17
5−1−29 Preflight1.When customs notification is required on
flights to Canada and Mexico and a predeparture
flight plan cannot be filed or an advise customs
message (ADCUS) cannot be included in a
predeparture flight plan, call the nearest en routedomestic or International FSS as soon as radio
communication can be established and file a VFR or
DVFR flight plan, as required, and include as the last
item the advise customs information. The station with
which such a flight plan is filed will forward it to the
appropriate FSS who will notify the customs officeresponsible for the destination airport.
2.If the pilot fails to include ADCUS in the
radioed flight plan, it will be assumed that other
arrangements have been made and FAA will notadvise customs.
3.The FAA assumes no responsibility for any
delays in advising customs if the flight plan is given
too late for delivery to customs before arrival of theaircraft. It is still the pilot’s responsibility to give
timely notice even though a flight plan is given to
FAA .
4.Air Commerce Regulations of the Treasury
Department’s Customs Service require all private
aircraft arriving in the U.S. via:
(a)The U.S./Mexican border or the Pacific
Coast from a foreign place in the WesternHemisphere south of 33 degrees north latitude and
between 97 degrees and 120 degrees west longitude;
or
(b)The Gulf of Mexico and Atlantic Coasts
from a foreign place in the W estern Hemisphere south
of 30 degrees north latitude, must furnish a notice of
arrival to the Customs service at the nearestdesignated airport. This notice may be furnished
directly to Customs by:
(1)Radio through the appropriate FAA
Flight Service Station.
(2)Normal FAA flight plan notification
procedures (a flight plan filed in Mexico does not
meet this requirement due to unreliable relay of data);
or
(3)Directly to the district Director of
Customs or other Customs officer at place of firstintended landing but must be furnished at least 1 hour
prior to crossing the U.S./Mexican border or the U.S.
coastline.(c)This notice will be valid as long as actual
arrival is within 15 minutes of the original ETA,
otherwise a new notice must be given to Customs.
Notices will be accepted up to 23 hours in advance.
Unless an exemption has been granted by Customs,private aircraft are required to make first landing in
the U.S. at one of the following designated airports
nearest to the point of border of coastline crossing:
Designated Airports
ARIZONA
Bisbee Douglas Intl Airport
Douglas Municipal AirportNogales Intl AirportTucson Intl AirportYuma MCAS −Yuma Intl Airport
CALIFORNIA
Calexico Intl AirportBrown Field Municipal Airport (San Diego)
FLORIDA
Fort Lauderdale Executive AirportFort Lauderdale/Hollywood Intl AirportKey West Intl Airport (Miami Intl Airport)Opa Locka Airport (Miami)Kendall−Tamiami Executive Airport (Miami)
St. Lucie County Intl Airport (Fort Pierce)Tampa Intl AirportPalm Beach Intl Airport (West Palm Beach)
LOUISANA
New Orleans Intl Airport (Moisant Field)New Orleans Lakefront Airport
NEW MEXICO
Las Cruces Intl Airport
NORTH CAROLINA
New Hanover Intl Airport (Wilmington)
TEXAS
Brownsville/South Padre Island Intl AirportCorpus Christi Intl AirportDel Rio Intl AirportEagle Pass Municipal AirportEl Paso Intl AirportWilliam P. Hobby Airport (Houston)Laredo Intl AirportMcAllen Miller Intl AirportPresidio Lely Intl Airport
AIM 10/12/17
5−1−30 Preflight5−1−12. Change in Flight Plan
a.In addition to altitude or flight level, destination
and/or route changes, increasing or decreasing the
speed of an aircraft constitutes a change in a flight
plan. Therefore, at any time the average true airspeed
at cruising altitude between reporting points varies or
is expected to vary from that given in the flight planby plus or minus 5 percent, or 10 knots, whichever is
greater, ATC should be advised.
b.All changes to existing flight plans should be
completed more than 46 minutes prior to theproposed departure time. Changes must be made with
the initial flight plan service provider. If the initial
flight plan’s service provider is unavailable, filersmay contact an ATC facility or FSS to make the
necessary revisions. Any revision 46 minutes or less
from the proposed departure time must be coordinat-
ed through an ATC facility or FSS.
5−1−13. Change in Proposed Departure
Time
a.To prevent computer saturation in the en route
environment, parameters have been established to
delete proposed departure flight plans which have not
been activated. Most centers have this parameter setso as to delete these flight plans a minimum of 2 hours
after the proposed departure time or Expect
Departure Clearance Time (EDCT). To ensure that aflight plan remains active, pilots whose actual
departure time will be delayed 2 hours or more
beyond their filed departure time, are requested tonotify ATC of their new proposed departure time.
b.Due to traffic saturation, ATC personnel
frequently will be unable to accept these revisions via
radio. It is recommended that you forward theserevisions to a flight plan service provider or FSS.
5−1−14. Closing VFR/DVFR Flight Plans
A pilot is responsible for ensuring that his/her VFR or
DVFR flight plan is canceled. You should close your
flight plan with the nearest FSS, or if one is not
available, you may request any ATC facility to relayyour cancellation to the FSS.
Control towers do not
automatically close VFR or DVFR flight plans since
they do not know if a particular VFR aircraft is on aflight plan. If you fail to report or cancel your flight
plan wit hin
1/2 hour after your ETA, search and rescue
procedures are started.REFERENCE −
14 CFR Section 91.153.14 CFR Section 91.169.
5−1−15. Canceling IFR Flight Plan
a.14 CFR Sections 91.153 and 91.169 include the
statement “When a flight plan has been activated, the
pilot-in-command, upon canceling or completing the
flight under the flight plan, must notify an FAA Flight
Service Station or ATC facility.”
b.An IFR flight plan may be canceled at any time
the flight is operating in VFR conditions outside
Class A airspace by pilots stating “CANCEL MY IFR
FLIGHT PLAN” to the controller or air/groundstation with which they are communicating.
Immediately after canceling an IFR flight plan, a pilot
should take the necessary action to change to theappropriate air/ground frequency , VFR radar beacon
code and VFR altitude or flight level.
c.ATC separation and information services will
be discontinued, including radar services (whereapplicable). Consequently, if the canceling flight
desires VFR radar advisory service, the pilot must
specifically request it.
NOTE−
Pilots must be aware that other procedures may beapplicable to a flight that cancels an IFR flight plan within
an area where a special program, such as a designatedTRSA, Class C airspace, or Class B airspace, has been
established.
d.If a DVFR flight plan requirement exists, the
pilot is responsible for filing this flight plan to replace
the canceled IFR flight plan. If a subsequent IFRoperation becomes necessary, a new IFR flight plan
must be filed and an ATC clearance obtained before
operating in IFR conditions.
e.If operating on an IFR flight plan to an airport
with a functioning control tower, the flight plan is
automatically closed upon landing.
f.If operating on an IFR flight plan to an airport
where there is no functioning control tower, the pilot
must initiate cancellation of the IFR flight plan. This
can be done after landing if there is a functioning FSS
or other means of direct communications with ATC.In the event there is no FSS and/or air/ground
communications with ATC is not possible below a
certain altitude, the pilot should, weather conditionspermitting, cancel the IFR flight plan while still
airborne and able to communicate with ATC by radio.
This will not only save the time and expense of
AIM 10/12/17
5−1−31 Preflightcanceling the flight plan by telephone but will quickly
release the airspace for use by other aircraft.
5−1−16. RNAV and RNP Operations
a.During the pre −flight planning phase the
availability of the navigation infrastructure required
for the intended operation, including any non −RNA V
contingencies, must be confirmed for the period of
intended operation. Availability of the onboard
navigation equipment necessary for the route to beflown must be confirmed.
b.If a pilot determines a specified RNP level
cannot be achieved, revise the route or delay the
operation until appropriate RNP level can be ensured.
c.The onboard navigation database must be
current and appropriate for the region of intended
operation and must include the navigation aids,
waypoints, and coded terminal airspace proceduresfor the departure, arrival and alternate airfields.
d.During system initialization, pilots of aircraft
equipped with a Flight Management System or other
RNA V−certified system, must confirm that the
navigation database is current, and verify that the
aircraft position has been entered correctly. Flightcrews should crosscheck the cleared flight plan
against charts or other applicable resources, as well as
the navigation system textual display and the aircraftmap display. This process includes confirmation of
the waypoints sequence, reasonableness of track
angles and distances, any altitude or speed
constraints, and identification of fly −by or fly−over
waypoints. A procedure must not be used if validityof the navigation database is in doubt.
e.Prior to commencing takeoff, the flight crew
must verify that the RNA V system is operatingcorrectly and the correct airport and runway data have
been loaded.
f.During the pre −flight planning phase RAIM
prediction must be performed if TSO −C129()
equipment is used to solely satisfy the RNA V and
RNP requirement. GPS RAIM availability must beconfirmed for the intended route of flight (route and
time) using current GPS satellite information. In the
event of a predicted, continuous loss of RAIM ofmore than five (5) minutes for any part of the intended
flight, the flight should be delayed, canceled, or
re−routed where RAIM requirements can be met.Operators may satisfy the predictive RAIM require-
ment through any one of the following methods:
1.Operators may monitor the status of each
satellite in its plane/slot position, by accounting forthe latest GPS constellation status (for example,
NOTAMs or NANUs), and compute RAIM availabil-
ity using model −specific RAIM prediction software;
2.Operators may use the Service Availability
Prediction Tool (SAPT) on the FAA en route and
terminal RAIM prediction website;
3.Operators may contact a Flight Service
Station (not DUATS) to obtain non −precision
approach RAIM;
4.Operators may use a third party interface,
incorporating FAA/VOLPE RAIM prediction data
without altering performance values, to predictRAIM outages for the aircraft’s predicted flight path
and times;
5.Operators may use the receiver’s installed
RAIM prediction capability (for TSO −C129a/Class
A1/B1/C1 equipment) to provide non
−precision
approach RAIM, accounting for the latest GPS
constellation status (for example, NOTAMs orNANUs). Receiver non −precision approach RAIM
should be checked at airports spaced at intervals not
to exceed 60 NM along the RNA V 1 procedure’s
flight track. “Terminal” or “Approach” RAIM must
be available at the ETA over each airport checked; or,
6.Operators not using model −specific software
or FAA/VOLPE RAIM data will need FAAoperational approval.
NOTE−
If TSO−C145/C146 equipment is used to satisfy the RNAV
and RNP r equir ement, the pilot/operator need not perform
the prediction if WAAS coverage is confirmed to beavailable along the entire route of flight. Outside the U.S.or in areas where WAAS coverage is not available,
operators using TSO −C145/C146 r eceivers are r equired to
check GPS RAIM availability.
5−1−17. Cold Temperature Operations
Pilots should begin planning for operating into
airports with cold temperatures during the preflight
planning phase. Instrument approach charts will
contain a snowflake symbol and a temperature when
cold temperature correction must be applied. Pilots
operating into airports requiring cold temperature
corrections should request the lowest forecast
AIM 10/12/17
5−1−32 Preflighttemperature at the airport for departure and arrival
times. If the temperature is forecast to be at or below
any published cold temperature restriction, calculate
an altitude correction for the appropriate segment(s)
and/or review procedures for operating automaticcold temperature compensating systems, as applica-
ble. The pilot is responsible to calculate and apply the
corrections to the af fected segment(s) when the actual
reported temperature is at or below any published
cold temperature restriction, or pilots with automatic
cold temperature compensating systems must ensurethe system is on and operating on each designated
segment. Advise ATC when intending to apply cold
temperature correction and of the amount of
correction required on initial contact (or as soon as
possible) for the intermediate segment and/or thepublished missed approach. This information is
required for ATC to provide aircraft appropriate
vertical separation between known traffic.
REFERENCE −
AIM, Paragraph 7 −2−3 , Altimeter Errors
AIM TBL 7 −2−3, ICAO Cold Temperature Error
AIM 10/12/17
5−2−1 Departure ProceduresSection 2. Departure Procedures
5−2−1. Pre-taxi Clearance Procedures
a.Certain airports have established pre-taxi clear-
ance programs whereby pilots of departinginstrument flight rules (IFR) aircraft may elect to re-
ceive their IFR clearances before they start taxiing for
takeoff. The following provisions are included insuch procedures:
1.Pilot participation is not mandatory.
2.Participating pilots call clearance delivery or
ground control not more than 10 minutes beforeproposed taxi time.
3.IFR clearance (or delay information, if
clearance cannot be obtained) is issued at the time of
this initial call-up.
4.When the IFR clearance is received on
clearance delivery frequency, pilots call ground
control when ready to taxi.
5.Normally, pilots need not inform ground
control that they have received IFR clearance on
clearance delivery frequency. Certain locations may,however, require that the pilot inform ground control
of a portion of the routing or that the IFR clearance
has been received.
6.If a pilot cannot establish contact on clearance
delivery frequency or has not received an IFRclearance before ready to taxi, the pilot should contact
ground control and inform the controller accordingly.
b.Locations where these procedures are in effect
are indicated in the Chart Supplement U.S.
5−2−2. Automated Pre −Departure Clear-
ance Procedures
a.Many airports in the National Airspace System
are equipped with the Terminal Data Link System(TDLS) that includes the Pre −Departure Clearance
(PDC) and Controller Pilot Data Link Communica-
tion–Departure Clearance (CPDLC-DCL) functions.
Both the PDC and CPDLC-DCL functions automate
the Clearance Delivery operations in the ATCT for
participating users. Both functions display IFR clear-
ances from the ARTCC to the ATCT. The Clearance
Delivery controller in the ATCT can append local de-
parture information and transmit the clearance viadata link to participating airline/service provider
computers for PDC. The airline/service provider will
then deliver the clearance via the Aircraft Commu-
nications Addressing and Reporting System
(ACARS) or a similar data link system, or fornon-data link equipped aircraft, via a printer located
at the departure gate. For CPDLC-DCL, the departure
clearance is uplinked from the ATCT via the FutureAir Navigation System (FANS) to the aircraft avion-
ics and requires a response from the flight crew. Both
PDC and CPDLC-DCL reduce frequency conges-tion, controller workload, and are intended to
mitigate delivery/read back errors.
b.Both services are available only to participating
aircraft that have subscribed to the service through an
approved service provider.
c.In all situations, the pilot is encouraged to con-
tact clearance delivery if a question or concern exists
regarding an automated clearance. Due to technical
reasons, the following limitations/differences existbetween the two services:
1. PDC
(a)Aircraft filing multiple flight plans are
limited to one PDC clearance per departure airportwithin an 18 −hour period. Additional clearances will
be delivered verbally.
(b)If the clearance is revised or modified pri-
or to delivery, it will be rejected from PDC and theclearance will need to be delivered verbally.
(c)No acknowledgment of receipt or read
back is required for a PDC.
2. CPDLC −DCL
(a)No limitation to the number of clearances
received.
(b)Allows delivery of revised flight data, in-
cluding revised departure clearances.
(c)A response from the flight crew is re-
quired.
(d)Requires a logon using the International
Civil Aviation Organization (ICAO) airport facility
identification (for example, KSLC utilizing the ATC
FANS application).
(e)To be eligible, operators must have re-
ceived CPDLC/FANS authorization from the
AIM 10/12/17
5−2−2 Departure Proceduresresponsible civil aviation authority, and file appropri-
ate equipment information in ICAO field 10a and in
the ICAO field 18 DA T (Other Data Applications) of
the flight plan.
5−2−3. Taxi Clearance
Pilots on IFR flight plans should communicate with
the control tower on the appropriate ground control orclearance delivery frequenc y, prior to starting en-
gines, to receive engine start time, taxi and/or
clearance information.
5−2−4. Line Up and Wait (LUAW)
a.Line up and wait is an air traffic control (ATC)
procedure designed to position an aircraft onto the
runway for an imminent departure. The ATC
instruction “LINE UP AND W AIT” is used to instruct
a pilot to taxi onto the departure runway and line up
and wait.
EXAMPLE −
Tower: “N234AR Runway 24L, line up and wait.”
b.This ATC instruction is not an authorization to
takeoff. In instances where the pilot has beeninstructed to line up and wait and has been advised of
a reason/condition (wake turbulence, traffic on an
intersecting runway, etc.) or the reason/condition isclearly visible (another aircraft that has landed on or
is taking off on the same runway), and the reason/
condition is satisfied, the pilot should expect an
imminent takeoff clearance, unless advised of a
delay. If you are uncertain about any ATC instruction
or clearance, contact ATC immediately.
c.If a takeoff clearance is not received within a
reasonable amount of time after clearance to line up
and wait, ATC should be contacted.
EXAMPLE −
Aircraft: Cessna 234AR holding in position Runway 24L.
Aircraft: Cessna 234AR holding in position Runway 24Lat Bravo.
NOTE−
F AA analysis of accidents and incidents involving aircraftholding in position indicate that two minutes or moreelapsed between the time the instruction was issued to line
up and wait and the r esulting event (for example, land −over
or go−around). Pilots should consider the length of time
that they have been hold ing in position whenever theyHAVE NOT been advised of any expected delay to
determine when it is appropriate to query the controller.
REFERENCE −
Advisory Cir culars 91−73A, Part 91 and Part 135 Single −Pilot Proced-
ures during Taxi Operations, and 120 −74A, Parts 91, 121, 125, and 135
Flightcrew Procedures during Taxi Operations
d.Situational awareness during line up and wait
operations is enhanced by monitoring ATC
instructions/clearances issued to other aircraft. Pilots
should listen carefully if another aircraft is on
frequency that has a similar call sign and pay close
attention to communications between ATC and other
aircraft. If you are uncertain of an ATC instruction or
clearance, query ATC immediately. Care should betaken to not inadvertently execute a clearance/
instruction for another aircraft.
e.Pilots should be especially vigilant when
conducting line up and wait operations at night or
during reduced visibility conditions. They shouldscan the full length of the runway and look for aircraft
on final approach or landing roll out when taxiing
onto a runway. ATC should be contacted anytimethere is a concern about a potential conflict.
f.When two or more runways are active, aircraft
may be instructed to “LINE UP AND W AIT” on two
or more runways. When multiple runway operations
are being conducted, it is important to listen closely
for your call sign and runway. Be alert for similar
sounding call signs and acknowledge all instructions
with your call sign. When you are holding in position
and are not sure if the takeoff clearance was for you,
ask ATC before you begin takeoff roll. ATC prefersthat you confirm a takeoff clearance rather than
mistake another aircraft’s clearance for your own.
g.When ATC issues intersection “line up and
wait” and takeoff clearances, the intersection
designator will be used. If AT C omits the intersection
designator, call ATC for clarification.
EXAMPLE −
Aircraft: “Cherokee 234AR, Runway 24L at November 4,
line up and wait.”
h.If landing traffic is a factor during line up and
wait operations, ATC will inform the aircraft in
position of the closest traffic within 6 flying miles re-
questing a full−stop, touch −and−go, stop−and−go, or
an unrestricted low approach to the same runway.
Pilots should take care to note the position of landing
traffic. A TC will also advise the landing traffic when
an aircraft is authorized to “line up and wait” on the
same runway.
AIM 10/12/17
5−2−3 Departure ProceduresEXAMPLE −
Tower: “Cessna 234AR, Runway 24L, line up and wait.Traffic a Boeing 737, six mile final.”Tower: “Delta 1011, continue, traffic a Cessna 210
holding in position Runway 24L.”
NOTE−
ATC will normally withhold landing clearance to arrival
aircraft when another aircraft is in position and holding on
the runway.
i.Never land on a runway that is occupied by
another aircraft, even if a landing clearance was
issued. Do not hesitate to ask the controller about the
traffic on the runway and be prepared to execute a go −
around.
NOTE−
Always clarify any misunderstanding or confusionconcerning ATC instructions or clearances. ATC should be
advised immediately if there is any uncertainty about theability to comply with any of their instructions.
5−2−5. Abbreviated IFR Departure Clear-
ance (Cleared. . .as Filed) Procedures
a.ATC facilities will issue an abbreviated IFR de-
parture clearance based on the ROUTE of flight filed
in the IFR flight plan, provided the filed route can be
approved with little or no revision. These abbreviated
clearance procedures are based on the following
conditions:
1.The aircraft is on the ground or it has departed
visual flight rules (VFR) and the pilot is requesting
IFR clearance while airborne.
2.That a pilot will not accept an abbreviated
clearance if the route or destination of a flight planfiled with ATC has been changed by the pilot or the
company or the operations officer before departure.
3.That it is the responsibility of the company or
operations office to inform the pilot when they make
a change to the filed flight plan.
4.That it is the responsibility of the pilot to
inform A TC in the initial call-up (for clearance) when
the filed flight plan has been either:
(a)Amended, or
(b)Canceled and replaced with a new filed
flight plan.
NOTE−
The facility issuing a clearance may not have r eceived therevised r oute or the revised flight plan by the time a pilot re-
quests clearance.
b.Controllers will issue a detailed clearance when
they know that the original filed flight plan has beenchanged or when the pilot requests a full route clear-
ance.
c.The clearance as issued will include the destina-
tion airport filed in the flight plan.
d.ATC procedures now require the controller to
state the DP name, the current number and the DP
transition name after the phrase “Cleared to (destina-
tion) airport” and prior to the phrase, “then as filed,”
for ALL departure clearances when the DP or DP
transition is to be flown. The procedures apply wheth-
er or not the DP is filed in the flight plan.
e.STARs, when filed in a flight plan, are consid-
ered a part of the filed route of flight and will not
normally be stated in an initial departure clearance. If
the ARTCC’s jurisdictional airspace includes boththe departure airport and the fix where a STAR or
STAR transition begins, the STAR name, the current
number and the STAR transition name MAY be stated
in the initial clearance.
f.“Cleared to (destination) airport as filed” does
NOT include the en route altitude filed in a flight plan.
An en route altitude will be stated in the clearance or
the pilot will be advised to expect an assigned or filedaltitude within a given time frame or at a certain point
after departure. This may be done verbally in the de-
parture instructions or stated in the DP.
g.In both radar and nonradar environments, the
controller will state “Cleared to (destination) airportas filed” or:
1.If a DP or DP transition is to be flown, specify
the DP name, the current DP number, the DP
transition name, the assigned altitude/flight level, and
any additional instructions (departure control fre-quency, beacon code assignment, etc.) necessary to
clear a departing aircraft via the DP or DP transition
and the route filed.
EXAMPLE −
National Seven T wenty cleared to Miami Airport Intercon-
tinental one departure, Lake Charles transition then asfiled, maintain Flight Level two seven zero.
2.When there is no DP or when the pilot cannot
accept a DP, the controller will specify the assignedaltitude or flight level, and any additional instructions
necessary to clear a departing aircraft via an
appropriate departure routing and the route filed.
AIM 10/12/17
5−2−4 Departure ProceduresNOTE−
A detailed departure route description or a radar vectormay be used to achieve the desired departure routing.
3.If it is necessary to make a minor revision to
the filed route, the controller will specify the assigned
DP or DP transition (or departure routing), the
revision to the filed route, the assigned altitude orflight level and any additional instructions necessary
to clear a departing aircraft.
EXAMPLE −
Jet Star One Four Two Four cleared to Atlanta Airport,South Boston two departure then as filed except change
route to r ead South Boston Victor 20 Gr eensboro, maintain
one seven thousand.
4.Additionally, in a nonradar environment, the
controller will specify one or more fixes, as
necessary, to identify the initial route of flight.
EXAMPLE −
Cessna Three One Six Zero Foxtrot cleared to Charlotte
Airport as filed via Brooke, maintain seven thousand.
h.To ensure success of the program, pilots should:
1.Avoid making changes to a filed flight plan
just prior to departure.
2.State the following information in the initial
call-up to the facility when no change has been made
to the filed flight plan: Aircraft call sign, location,
type operation (IFR) and the name of the airport (orfix) to which you expect clearance.
EXAMPLE −
“Washington clearance delivery (or ground control if ap-propriate) American Seventy Six at gate one, IFRLos Angeles.”
3.If the flight plan has been changed, state the
change and request a full route clearance.
EXAMPLE −
“Washington clearance delivery, American Seventy Six atgate one. IFR San Francisco. My flight plan route has been
amended (or destination changed). Request full routeclearance.”
4.Request verification or clarification from
ATC if ANY portion of the clearance is not clearly
understood.
5.When requesting clearance for the IFR
portion of a VFR/IFR flight, request such clearanceprior to the fix where IFR operation is proposed to
commence in sufficient time to avoid delay. Use the
following phraseology:EXAMPLE −
“Los Angeles center, Apache Six One Papa, VFR estimat-ing Paso Robles VOR at three two, one thousand fivehundred, request IFR to Bakersfield.”
5−2−6. Departure Restrictions, Clearance
Void Times, Hold for Release, and ReleaseTimes
a.ATC may assign departure restrictions, clear-
ance void times, hold for release, and release times,when necessary, to separate departures from other
traffic or to restrict or regulate the departure flow.
1. Clearance V oid T imes. A pilot may receive
a clearance, when operating from an airport without
a control tower, which contains a provision for theclearance to be void if not airborne by a specific time.
A pilot who does not depart prior to the clearance void
time must advise ATC as soon as possible of theirintentions. ATC will normally advise the pilot of the
time allotted to notify ATC that the aircraft did not
depart prior to the clearance void time. This timecannot exceed 30 minutes. Failure of an aircraft to
contact ATC within 30 minutes after the clearance
void time will result in the aircraft being consideredoverdue and search and rescue procedures initiated.
NOTE−
1.Other IFR traffic for the airport where the clearance is
issued is suspended until the aircraft has contacted ATC or
until 30 minutes after the clearance void time or 30 minutes
after the clearance release time if no clearance void timeis issued.
2.Pilots who depart at or after their clearance void time
are not afforded IFR separation and may be in violation of
14 CFR Section 91.173 which requires that pilots receive
an appropriate ATC clearance before operating IFR incontrolled airspace.
EXAMPLE −
Clearance void if not off by (clearance void time) and, if re-
quired, if not off by (clearance void time) advise (facility)
not later than (time) of intentions.
2. Hold for Release. ATC may issue “hold for
release” instructions in a clearance to delay anaircraft’s departure for traffic management reasons
(i.e., weather, traffic volume, etc.). When ATC states
in the clearance, “hold for release,” the pilot may notdepart utilizing that IFR clearance until a release time
or additional instructions are issued by ATC. In
addition, ATC will include departure delay informa-tion in conjunction with “hold for release”
instructions. The ATC instruction, “hold for release,”
applies to the IFR clearance and does not prevent the
AIM 10/12/17
5−2−5 Departure Procedurespilot from departing under VFR. However, prior to
takeoff the pilot should cancel the IFR flight plan and
operate the transponder on the appropriate VFR code.
An IFR clearance may not be available after
departure.
EXAMPLE −
(Aircraft identification) clear ed to (destination) airport as
filed, maintain (altitude), and, if required (additional in-
structions or information), hold for r elease, expect (time in
hours and/or minutes) departure delay.
3. Release Times. A “release time” is a
departure restriction issued to a pilot by ATC,specifying the earliest time an aircraft may depart.
ATC will use “release times” in conjunction with
traffic management procedures and/or to separate adeparting aircraft from other traffic.
EXAMPLE −
(Aircraft identification) released for departure at (time inhours and/or minutes).
4. Expect Departure Clearance Time
(EDCT). The EDCT is the runway release time
assigned to an aircraft included in traffic management
programs. Aircraft are expected to depart no earlier
than 5 minutes before, and no later than 5 minutesafter the EDCT.
b.If practical, pilots departing uncontrolled air-
ports should obtain IFR clearances prior to becoming
airborne when two-way communications with thecontrolling ATC facility is available.
5−2−7. Departure Control
a.Departure Control is an approach control func-
tion responsible for ensuring separation betweendepartures. So as to expedite the handling of depar-
tures, Departure Control may suggest a takeoff
direction other than that which may normally havebeen used under VFR handling. Many times it is pre-
ferred to offer the pilot a runway that will require the
fewest turns after takeoff to place the pilot on course
or selected departure route as quickly as possible. At
many locations particular attention is paid to the use
of preferential runways for local noise abatement pro-grams, and route departures away from congested
areas.
b.Departure Control utilizing radar will normally
clear aircraft out of the terminal area using DPs via ra-
dio navigation aids.
1.When a departure is to be vectored
immediately following takeoff, the pilot will beadvised prior to takeoff of the initial heading to be
flown but may not be advised of the purpose of the
heading. When the initial heading will take the
aircraft off an assigned procedure (for example, an
RNA V SID with a published lateral path to awaypoint and crossing restrictions from the departure
end of runway), the controller will assign an altitude
to maintain with the initial heading.
2.At some airports when a departure will fly an
RNA V SID that begins at the runway, ATC may
advise aircraft of the initial fix/waypoint on the
RNAV route. The purpose of the advisory is to remind
pilots to verify the correct procedure is programmed
in the FMS before takeoff. Pilots must immediately
advise A TC if a different RNA V SID is entered in the
aircraft’s FMC. When this advisory is absent, pilots
are still required to fly the assigned SID as published.
EXAMPLE −
Delta 345 RNAV to MP ASS, Runway26L, cleared fortakeoff.
NOTE−
1.The SID transition is not restated as it is contained in the
ATC clearance.
2.Aircraft cleared via RNAV SIDs designed to begin with
a vector to the initial waypoint are assigned a heading be-fore departure.
3.Pilots operating in a radar environment are
expected to associate departure headings or an RNA V
departure advisory with vectors or the flight path to
their planned route or flight. When given a vectortaking the aircraft off a previously assigned nonradar
route, the pilot will be advised briefly what the vector
is to achieve. Thereafter, radar service will beprovided until the aircraft has been reestablished
“on-course” using an appropriate navigation aid and
the pilot has been advised of the aircraft’s position ora handoff is made to another radar controller with
further surveillance capabilities.
c.Controllers will inform pilots of the departure
control frequencies and, if appropriate, the transpon-
der code before takeoff. Pilots must ensure their
transponder is adjusted to the “on” or normal operat-
ing position as soon as practical and remain on duringall operations unless otherwise requested to change to
“standby” by ATC. Pilots should not change to the de-
parture control frequency until requested. Controllersmay omit the departure control frequency if a DP has
or will be assigned and the departure control fre-
quency is published on the DP.
AIM 10/12/17
5−2−6 Departure Procedures5−2−8. Instrument Departure Procedures
(DP) − Obstacle Departure Procedures
(ODP) and Standard Instrument Departures(SID)
Instrument departure procedures are preplanned in-
strument flight rule (IFR) procedures which provide
obstruction clearance from the terminal area to the
appropriate en route structure. There are two types of
DPs, Obstacle Departure Procedures (ODPs), printed
either textually or graphically, and Standard Instru-
ment Departures (SIDs), always printed graphically.All DPs, either textual or graphic may be designed us-
ing either conventional or RNA V criteria. RNA V
procedures will have RNA V printed in the title,e.g., SHEAD TWO DEPARTURE (RNA V). ODPs
provide obstruction clearance via the least onerous
route from the terminal area to the appropriate enroute structure. ODPs are recommended for obstruc-
tion clearance and may be flown without ATC
clearance unless an alternate departure procedure(SID or radar vector) has been specifically assigned
by ATC. Graphic ODPs will have (OBSTACLE)
printed in the procedure title, e.g., GEYSR THREEDEPARTURE (OBSTACLE), or, CROWN ONE
DEPARTURE (RNA V) (OBSTACLE). Standard In-
strument Departures are air traffic control (ATC)procedures printed for pilot/controller use in graphic
form to provide obstruction clearance and a transition
from the terminal area to the appropriate en route
structure. SIDs are primarily designed for system en-
hancement and to reduce pilot/controller workload.ATC clearance must be received prior to flying a SID.
All DPs provide the pilot with a way to depart the air-
port and transition to the en route structure safely.Pilots operating under 14 CFR Part 91 are strongly
encouraged to file and fly a DP at night, during mar-
ginal Visual Meteorological Conditions (VMC) andInstrument Meteorological Conditions (IMC), when
one is available. The following paragraphs will pro-
vide an overview of the DP program, why DPs aredeveloped, what criteria are used, where to find them,
how they are to be flown, and finally pilot and ATC
responsibilities.
a.Why are DPs necessary? The primary reason is
to provide obstacle clearance protection information
to pilots. A secondary reason, at busier airports, is to
increase efficiency and reduce communications anddeparture delays through the use of SIDs. When an in-
strument approach is initially developed for an
airport, the need for DPs is assessed. The proceduredesigner conducts an obstacle analysis to support de-
parture operations. If an aircraft may turn in any
direction from a runway within the limits of the as-
sessment area (see paragraph 5 −2−8b3) and remain
clear of obstacles, that runway passes what is calleda diverse departure assessment and no ODP will be
published. A SID may be published if needed for air
traffic control purposes. However, if an obstacle pen-
etrates what is called the 40:1 obstacle identification
surface, then the procedure designer chooses whether
to:
1.Establish a steeper than normal climb
gradient; or
2.Establish a steeper than normal climb
gradient with an alterna tive that increases takeoff
minima to allow the pilot to visually remain clear of
the obstacle(s); or
3.Design and publish a specific departure route;
or
4.A combination or all of the above.
b.What criteria is used to provide obstruction
clearance during departure?
1.Unless specified otherwise, required obstacle
clearance for all departures, including diverse, is
based on the pilot crossing the departure end of the
runway at least 35 feet above the departure end of
runway elevation, climbing to 400 feet above the
departure end of runway elevation before making the
initial turn, and maintaining a minimum climb
gradient of
200 feet per nautical mile (FPNM), unless
required to level off by a crossing restriction, until the
minimum IFR altitude. A greater climb gradient may
be specified in the DP to clear obstacles or to achieve
an ATC crossing restriction. If an initial turn higherthan 400 feet above the departure end of runway
elevation is specified in the DP, the turn should be
commenced at the higher altitude. If a turn isspecified at a fix, the turn must be made at that fix.
Fixes may have minimum and/or maximum crossing
altitudes that must be adhered to prior to passing thefix. In rare instances, obstacles that exist on the
extended runway centerline may make an “early
turn” more desirable than proceeding straight ahead.In these cases, the published departure instructions
will include the language “turn left(right) as soon as
practicable.” These departures will also include aceiling and visibility minimum of at least 300 and 1.
Pilots encountering one of these DPs should preplan
the climb out to gain altitude and begin the turn as
AIM 10/12/17
5−2−7 Departure Proceduresquickly as possible within the bounds of safe
operating practices and operating limitations. This
type of departure procedure is being phased out.
NOTE−
“Practical” or “feasible” may exist in some existing de-
parture text instead of “practicable.”
2.ODPs and SIDs assume normal aircraft
performance, and that all engines are operating.Development of contingency procedures, required
to cover the case of an engine failure or other
emergency in flight that may occur after liftoff, is
the responsibility of the operator. (More detailed
information on this subject is available in AdvisoryCircular AC 120 −91, Airport Obstacle Analysis, and
in the “Departure Procedures” section of chapter 2 in
the Instrument Procedures Handbook,FAA−H−8083−16.)
3.The 40:1 obstacle identification surface
(OIS) begins at the departure end of runway (DER)
and slopes upward at 152 FPNM until reaching theminimum IFR altitude or entering the en route
structure. This assessment area is limited to 25 NM
from the airport in nonmountainous areas and 46 NM
in designated mountainous areas. Beyond this
distance, the pilot is responsible for obstacle
clearance if not operating on a published route, if
below (having not reached) the MEA or MOCA of a
published route, or an ATC assigned altitude. SeeFIG 5−2−1. (Ref 14 CFR 91.177 for further
information on en route altitudes.)NOTE−
ODPs are normally designed to terminate within these dis-
tance limitations, however, some ODPs will contain r outes
that may exceed 25/46 NM; these routes will ensure
obstacle protection until reaching the end of the ODP .
4.Obstacles that are located within 1 NM of the
DER and penetrate the 40:1 OCS are referred to as
“low, close −in obstacles.” The standard required
obstacle clearance (ROC) of 48 feet per NM to clear
these obstacles would require a climb gradient greater
than 200 feet per NM for a very short distance, onlyuntil the aircraft was 200 feet above the DER. To
eliminate publishing an excessive climb gradient, the
obstacle AGL/MSL height and location relative to the
DER is noted in the “Take −off Minimums and
(OBSTACLE) Departure Procedures” section of a
given Terminal Procedures Publication (TPP)booklet. The purpose of this note is to identify the
obstacle(s) and alert the pilot to the height and
location of the obstacle(s) so they can be avoided.This can be accomplished in a variety of ways, e.g.,
the pilot may be able to see the obstruction and
maneuver around the obstacle(s) if necessary; earlyliftoff/climb performance may allow the aircraft to
cross well above the obstacle(s); or if the obstacle(s)
cannot be visually acquired during departure,preflight planning should take into account what
turns or other maneuver may be necessary
immediately after takeoff to avoid the obstruction(s).
FIG 5−2−1
Diverse Departure Obstacle Assessment to 25/46 NM
AIM 10/12/17
5−2−8 Departure Procedures5.Climb gradients greater than 200 FPNM are
specified when required to support procedure design
constraints, obstacle clearance, and/or airspace
restrictions. Compliance with a climb gradient for
these purposes is mandatory when the procedure ispart of the ATC clearance, unless increased takeoff
minimums are provided and weather conditions
allow compliance with these minimums. Addition-ally, ATC required crossing restrictions may also
require climb gradients greater than 200 FPNM.
These climb gradients may be amended or canceledat ATC’s discretion. Multiple ATC climb gradients
are permitted. An ATC climb gradient will not be
used on an ODP.
EXAMPLE −
“Cross ALPHA intersection at or below 4000; maintain6000.” The pilot climbs at least 200 FPNM to 6000. If 4000
is reached before ALPHA, the pilot levels off at 4000 until
passing ALPHA; then immediately resumes at least 200FPNM climb.
EXAMPLE −
“TAKEOFF MINIMUMS: RWY 27, Standard with a min-
imum climb of 280’ per NM to 2500, ATC climb of 310’ per
NM to 4000 ft.” A climb of at least 280 FPNM is required
to 2500 and is mandatory when the departure pr ocedure is
included in the ATC clearance. ATC r equires a climb gradi-
ent of 310 FPNM to 4000, however, this ATC climb
gradient may be amended or canceled.
6.Climb gradients may be specified only to an
altitude/fix, above which the normal gradient applies.
EXAMPLE −
“Minimum climb 340 FPNM to ALPHA.” The pilot climbs
at least 340 FPNM to ALPHA, then at least 200 FPNM to
MIA.
7.A Visual Climb Over Airport (VCOA)
procedure is a departure option for an IFR aircraft,
operating in visual meteorological conditions equal
to or greater than the specified visibility and ceiling,to visually conduct climbing turns over the airport to
the published “climb −to” altitude from which to
proceed with the instrument portion of the departure.
VCOA procedures are developed to avoid obstacles
greater than 3 statute miles from the departure end of
the runway as an alternative to complying with climbgradients greater than 200 feet per nautical mile.
Pilots are responsible to advise ATC as early as
possible of the intent to fly the VCOA option prior to
departure. These textual procedures are published in
the Take-Off Minimums and (Obstacle) Departure
Procedures section of the Terminal ProceduresPublications and/or appear as an option on a Graphic
ODP.
EXAMPLE −
“Climb in visual conditions so as to cross the McElory Air-
port southbound, at or above 6000, then climb viaKeemmling radial zero three three to Keemmling VOR-
TAC.”
c.Who is responsible for obstacle clearance? DPs
are designed so that adherence to the procedure by thepilot will ensure obstacle protection. Additionally:
1.Obstacle clearance responsibility also rests
with the pilot when he/she chooses to climb in visual
conditions in lieu of flying a DP and/or depart under
increased takeoff minima rather than fly the climb
gradient. Standard takeoff minima are one statutemile for aircraft having two engines or less and
one−half statute mile for aircraft having more than
two engines. Specified ceiling and visibility minima(VCOA or increased takeoff minima) will allow
visual avoidance of obstacles until the pilot enters the
standard obstacle protec tion area. Obstacle avoid-
ance is not guaranteed if the pilot maneuvers farther
from the airport than the specified visibility minimum
prior to reaching the specified altitude. DPs may also
contain what are called Low Close in Obstacles.
These obstacles are less than 200 feet above thedeparture end of runway elevation and within
one NM of the runway end, and do not require
increased takeoff minimums. These obstacles areidentified on the SID chart or in the Take −off
Minimums and (Obstacle) Departure Procedures
section of the U. S. Terminal Procedure booklet.These obstacles are especially critical to aircraft that
do not lift off until close to the departure end of the
runway or which climb at the minimum rate. Pilotsshould al so consider drift following lift −off to ensure
sufficient clearance from these obstacles. That
segment of the procedure that requires the pilot to see
and avoid obstacles ends when the aircraft crosses the
specified point at the required altitude. In all cases
continued obstacle clearance is based on havingclimbed a minimum of 200 feet per nautical mile to
the specified point and then continuing to climb at
least 200 foot per nautical mile during the departure
until reaching the minimum enroute altitude, unless
specified otherwise.
2.ATC may assume responsibility for obstacle
clearance by vectoring the aircraft prior to reaching
the minimum vectoring altitude by using a Diverse
Vector Area (DV A). The DV A may be established
AIM 10/12/17
5−2−9 Departure Proceduresbelow the Minimum Vectoring Altitude (MV A) or
Minimum IFR Altitude (MIA) in a radar environment
at the request of Air Traffic. This type of DP meets the
TERPS criteria for diverse departures, obstacles, and
terrain avoidance in which random radar vectorsbelow the MV A/MIA may be issued to departing
aircraft. The DV A has been assessed for departures
which do not follow a specific ground track, but willremain within the specified area.
(a)The existence of a DV A will be noted in
the Takeoff Minimums and Obstacle Departure Pro-
cedure section of the U.S. Terminal Procedures
Publication (TPP). The T akeoff Departure procedure
will be listed first, followed by any applicable DV A.
EXAMPLE −
DIVERSE VECTOR AREA (RADAR VECTORS)
AMDT 1 14289 (F AA)
Rwy 6R , headings as assigned by ATC; requires
minimum climb of 290’ per NM to 400. Rwys 6L, 7L, 7R, 24R, 25R , headings as
assigned by ATC.
(b)Pilots should be aware that Air Traffic fa-
cilities may utilize a climb gradient greater than thestandard 200 FPNM in a DV A. This information will
be identified in the DV A text for pilot evaluation
against the aircraft’s available climb performance. Pi-
lots should note that the DV A has been assessed for
departures which do not follow a specific ground
track. ATC may also vector an aircraft off a previ-ously assigned DP. In all cases, the minimum 200
FPNM climb gradient is assumed unless a higher
climb gradient is specified on the departure, andobstacle clearance is not provided by ATC until the
controller begins to provide navigational guidance in
the form of radar vectors.
NOTE−
As is always the case, when used by the controller duringdeparture, the term “radar contact” should not be inter-
preted as r elieving pilots of their responsibility to maintain
appropriate terrain and obstruction clearance which mayinclude flying the obstacle DP .
3.Pilots must preplan to determine if the aircraft
can meet the climb gradient (expressed in feet per
nautical mile) required by the departure procedure,
and be aware that flying at a higher than anticipatedground speed increases the climb rate requirement in
feet per minute. Higher than standard climb gradients
are specified by a note on the departure procedurechart for graphic DPs, or in the Take −Off Minimums
and (Obstacle) Departure Procedures section of the
U.S. Terminal Procedures booklet for textual ODPs.
The required climb gradient, or higher, must be
maintained to the specified altitude or fix, then thestandard climb gradient of 200 ft/NM can be
resumed. A table for the conversion of climb gradient
(feet per nautical mile) to climb rate (feet per minute),
at a given ground speed, is included on the inside of
the back cover of the U.S. Terminal Procedures
booklets.
d.Where are DPs located? DPs will be listed by
airport in the IFR Takeoff Minimums and (Obstacle)
Departure Procedures Section, Section L, of the Ter-
minal Procedures Publications (TPPs). If the DP is
textual, it will be described in TPP Section L . SIDs
and complex ODPs will be published graphically and
named. The name will be listed by airport name and
runway in Section L. Graphic ODPs will also have the
term “(OBSTACLE)” printed in the charted proce-
dure title, differentiating them from SIDs.
1.An ODP that has been developed solely for
obstacle avoidance will be indicated with the symbol
“T” on appropriate Instrument Approach Procedure
(IAP) charts and DP charts for that airport. The “T”
symbol will continue to refer users to TPP Section C.
In the case of a graphic ODP, the TPP Section C will
only con tain the name of the ODP. Since there may be
both a textual and a graphic DP, Section C should still
be checked for additional information. The nonstan-
dard takeoff minimums and minimum climb
gradients found in TPP Section C also apply tocharted DPs and radar vector departures unless
different minimums are specified on the charted DP.
Takeoff minimums and departure procedures apply to
all runways unless otherwise specified. New graphic
DPs will have all the information printed on the
graphic depiction. As a general rule, ATC will onlyassign an ODP from a nontowered airport when
compliance with the ODP is necessary for aircraft to
aircraft separation. Pilots may use the ODP to help
ensure separation from terrain and obstacles.
e.Responsibilities
1.Each pilot, prior to departing an airport on an
IFR flight should:
(a)Consider the type of terrain and other ob-
stacles on or in the vicinity of the departure airport;
(b)Determine whether an ODP is available;
AIM 10/12/17
5−2−10 Departure Procedures(c)Determine if obstacle avoidance can be
maintained visually or if the ODP should be flown;
and
(d)Consider the ef fect of degraded climb per-
formance and the actions to take in the event of an
engine loss during the departure. Pilots should notify
ATC as soon as possible of reduced climb capability
in that circumstance.
NOTE−
Guidance concerning contingency procedures that
address an engine failure on takeoff after V 1 speed on a
large or turbine −powered transport category airplane
may be found in AC 120 −91, Airport Obstacle Analysis.
2.Pilots should not exceed a published speed
restriction associated with a SID waypoint untilpassing that waypoint.
3.After an aircraft is established on an SID and
subsequently vectored or cleared to deviate off of the
SID or SID transition, pilots must consider the SIDcanceled, unless the controller adds “expect to
resume SID;” pilots should then be prepared to rejoin
the SID at a subsequent fix or procedure leg. If the
SID contains published altitude restrictions, pilots
should expect the controller to issue an altitude tomaintain. ATC may also interrupt the vertical
navigation of a SID and provide alternate altitude
instructions while the aircraft remains established on
the published lateral path. Aircraft may not be
vectored off of an ODP or issued an altitude lower
than a published altitude on an ODP until at or above
the MV A/MIA, at which time the ODP is canceled.
4.Aircraft instructed to resume a SID procedure
such as a DP or SID which contains speed and/or
altitude restrictions, must be:
(a)Issued/reissued all applicable restrictions,
or
(b)Advised to “Climb via SID” or resume
published speed.
EXAMPLE −
“Resume the Solar One departure, Climb via SID.”“Proceed direct CIROS, resume the Solar One departure,Climb via SID.”
5.A clearance for a SID which does not contain
published crossing restrictions, and/or is a SID witha Radar Vector segment or a Radar Vector SID, will
be issued using the phraseology “Maintain ( alti-
tude).”6.A clearance for a SID which contains
published altitude restrictions may be issued using
the phraseology “climb via.” Climb via is an
abbreviated clearance that requires compliance with
the procedure lateral path, associated speed andaltitude restrictions along the cleared route or
procedure. Clearance to “climb via” authorizes the
pilot to:
(a)When used in the IFR departure clearance,
in a PDC, DCL or when cleared to a waypoint depict-
ed on a SID, to join the procedure after departure orto resume the procedure.
(b)When vertical navigation is interrupted
and an altitude is assigned to maintain which is not
contained on the published procedure, to climb from
that previously-assigned altitude at pilot’s discretionto the altitude depicted for the next waypoint.
(c)Once established on the depicted depar-
ture, to navigate laterally and climb to meet allpublished or assigned altitude and speed restrictions.
NOTE−
1.When otherwise cleared along a route or pr ocedure that
contains published speed restrictions, the pilot must com-ply with those speed restrictions independent of a climb via
clearance.
2.ATC anticipates pilots will begin adjusting speed the
minimum distance necessary prior to a published speed re-
striction so as to cross the waypoint/fix at the published
speed. Once at the published speed ATC expects pilots will
maintain the published speed until additional adjustmentis required to comply with further published or ATC as-
signed speed restrictions or as required to ensure
compliance with 14 CFR Section 91.117.
3.If ATC interrupts lateral/vertical navigation while an
aircraft is flying a SID, ATC must ensure obstacle clear-ance. When issuing a “climb via” clearance to join or
resume a procedure ATC must ensure obstacle clearance
until the aircraft is established on the lateral and verticalpath of the SID.
4.ATC will assign an altitude to cross if no altitude is de-
picted at a waypoint/fix or when otherwise necessary/
required, for an aircraft on a dir ect route to a waypoint/fix
where the SID will be joined or resumed.
5.SIDs will have a “top altitude;” the “top altitude” is the
charted “maintain” altitude contained in the procedure
description or assigned by ATC.
REFERENCE −
F AAO 7110.65, Paragraph 5-6-2, Methods
PCG, Climb Via, Top Altitude
AIM 10/12/17
5−2−11 Departure ProceduresEXAMPLE −
1.Lateral route clearance:
“Cleared Loop Six departure.”
NOTE−
The aircraft must comply with the SID lateral path, and any
published speed restrictions.
2.Routing with assigned altitude:
“Cleared Loop Six departure, climb and maintain
four thousand.”
NOTE−
The aircraft must comply with the SID lateral path, and anypublished speed restriction while climbing unrestricted tofour thousand.
3.(A pilot filed a flight plan to the Johnston Airport using
the Scott One departure, Jonez transition, then Q-145. Thepilot filed for FL350. The Scott One includes altituderestrictions, a top altitude and instructions to expect the
filed altitude ten minutes after departure). Before
departure ATC uses PDC, DCL or clearance delivery to
issue the clearance:
“Cleared to Johnston Airport, Scott One departure,
Jonez transition, Q-OneForty-five. Climb via SID.”
NOTE−
In Example 3, the aircraft must comply with the Scott Onedeparture lateral path and any published speed and alti-tude restrictions while climbing to the SID top altitude.
4.(Using the Example 3 flight plan, ATC determines the
top altitude must be changed to FL180). The clearance will
read:
“Cleared to Johnston Airport, Scott One departure,
Jonez transition, Q-One Forty-five, Climb via SID except
maintain flight level one eight zero.”
NOTE−
In Example 4, the aircraft must comply with the Scott One
departure lateral path and any published speed and alti-
tude restrictions while climbing to FL180. The aircraftmust stop climb at FL180 until issued further clearance by
ATC.
5.(An aircraft was issued the Suzan Two departure,
“climb via SID” in the IFR departure clearance. Afterdeparture ATC must change a waypoint crossing
restriction). The clearance will be:
“Climb via SID except cross Mkala at or above seven
thousand.”
NOTE−
In Example 5, the aircraft will comply with the Suzan Twodeparture lateral path and any published speed and alti-
tude r estrictions and climb so as to cross Mkala at or above
7,000; remainder of the departure must be flown as pub-
lished.6.(An aircraft was issued the Teddd One departure,
“climb via SID” in the IFR departure clearance. An
interim altitude of 10,000 was issued instead of the
published top altitude of FL 230). After departure ATC is
able to issue the published top altitude. The clearance will
be:
“Climb via SID.”
NOTE−
In Example 6, the air craft will track laterally and vertically
on the Teddd One departure and initially climb to 10,000;Once re-issued the “climb via” clearance the interim alti-tude is canceled aircraft will continue climb to FL230
while complying with published restrictions.
7.(An aircraft was issued the Bbear Two departure,
“climb via SID” in the IFR departure clearance. An
interim altitude of 16,000 was issued instead of the
published top altitude of FL 190). After departure, ATC is
able to issue a top altitude of FL300 and still requires
compliance with the published SID restrictions. The
clearance will be:
“Climb via SID except maintain flight level three zero
zero.”
NOTE−
In Example 7, the air craft will track laterally and vertically
on the Bbear Two departure and initially climb to 16,000;Once re-issued the “climb via” clearance the interim alti-tude is canceled and the aircraft will continue climb toFL300 while complying with published restrictions.
8.(An aircraft was issued the Bizee Two departure, “climb
via SID.” After departure, ATC vectors the aircraft off of
the SID, and then issues a direct routing to rejoin the SID
at Rockr waypoint which does not have a published altitude
restriction. ATC wants the aircraft to cross at or above
10,000). The clearance will read:
“Proceed direct Rockr, cross Rockr at or above
one-zero thousand, climb via the Bizee Two departure.”
NOTE−
In Example 8, the aircraft will join the Bizee Two SID at
Rockr at or above 10,000 and then comply with the pub-
lished lateral path and any published speed or altituderestrictions while climbing to the SID top altitude.
9.(An aircraft was issued the Suzan Two departure,
“climb via SID” in the IFR departure clearance. Afterdeparture ATC vectors the aircraft off of the SID, and then
clears the aircraft to rejoin the SID at Dvine waypoint,
which has a published crossing r estriction). The clearance
will read:
“Proceed direct Dvine, Climb via the Suzan Two
departure.”
NOTE−
In Example 9, the air craft will join the Suzan Two departure
at Dvine, at the published altitude, and then comply with
AIM 10/12/17
5−2−12 Departure Proceduresthe published lateral path and any published speed or alti-
tude restrictions.
7.Pilots cleared for vertical navigation using the
phraseology “climb via” must inform ATC, upon
initial contact, of the altitude leaving and anyassigned restrictions not published on the procedure.
EXAMPLE −
1.(Cactus 711 is cleared to climb via the Laura Two
departure. The Laura Two has a top altitude of FL190): “Cactus Seven Eleven leaving two thousand, climbing via
the Laura Two departure.”
2.(Cactus 711 is cleared to climb via the Laura Two
departure, but ATC changed the top altitude to16,000):
“Cactus Seven Eleven leaving two thousand for one-sixthousand, climbing via the Laura Two departure.”
8.If prior to or after takeoff an altitude
restriction is issued by ATC, all previously issued
“ATC” altitude restrictions are canceled including
those published on a SID. Pilots must still comply
with all speed restrictions and lateral path require-ments published on the SID unless canceled by ATC.
EXAMPLE −
Prior to takeoff or after departure ATC issues an altitude
change clearance to an aircraft clear ed to climb via a SID
but ATC no longer r equires compliance with published alti-tude restrictions:
“Climb and maintain flight level two four zero.”
NOTE−
The published SID altitude restrictions are canceled; Theaircraft should comply with the SID lateral path and begin
an unrestricted climb to FL240. Compliance with pub-
lished speed r estrictions is still r equired unless specifically
deleted by ATC.
9.Altitude restrictions published on an ODP are
necessary for obstacle clearance and/or design
constraints. Crossing altitudes and speed restrictions
on ODPs cannot be canceled or amended by ATC.
f.RNA V Departure Procedures
All public RNA V SIDs and graphic ODPs are
RNA V 1. These procedures generally start with an
initial RNA V or heading leg near the departure end of
runway (DER). In addition, these procedures require
system performance currently met by GPS or DME/
DME/IRU RNA V systems that satisfy the criteriadiscussed in AC 90 −100A, U.S. Terminal and En
Route Area Navigation (RNA V) Operations.
RNA V 1 procedures must maintain a total system er-
ror of not more than 1 NM for 95% of the total flight
time.
REFERENCE −
AIM, Global Positioning System (GPS)
Paragraph 1 −1−17 k, Impact of Magnetic Variation on PBN Systems
AIM 10/12/17
5−3−1 En Route ProceduresSection 3. En Route Procedures
5−3−1. ARTCC Communications
a. Direct Communications, Controllers and
Pilots.
1.ARTCCs are capable of direct communica-
tions with IFR air traffic on certain frequencies.
Maximum communications coverage is possiblethrough the use of Remote Center Air/Ground
(RCAG) sites comprised of both VHF and UHF
transmitters and receivers . These sites are located
throughout the U.S. Although they may be several
hundred miles away from the ARTCC, they are
remoted to the various ARTCCs by land lines ormicrowave links. Since IFR operations are expedited
through the use of direct communications, pilots are
requested to use these frequencies strictly for
communications pertinent to the control of IFR
aircraft. Flight plan filing, en route weather, weatherforecasts, and similar data should be requested
through FSSs, company radio, or appropriate military
facilities capable of performing these services.
2.An ARTCC is divided into sectors. Each
sector is handled by one or a team of controllers andhas its own sector discrete frequency. As a flight
progresses from one sector to another, the pilot is
requested to change to the appropriate sector discrete
frequency.
3.Controller Pilot Data Link Communications
(CPDLC) is a system that supplements air/ground
voice communications. As a result, it expands
two−way air traffic control air/ground communica-
tions capabilities. Consequently, the air traffic
system’s operational capacity is increased and any
associated air traffic delays become minimized. Arelated safety benefit is that pilot/controller read −
back and hear −back errors will be significantly
reduced. The CPDLC’s principal operating criteriaare:
(a)V oice remains the primary and controlling
air/ground communications means.
(b)Participating aircraft will need to have the
appropriate CPDLC avionics equipment in order to
receive uplink or transmit downlink messages.
(c)CPDLC Build 1 offers four ATC data link
services. These are altimeter setting (AS), transfer ofcommunications (TC), initial contact (IC), and menu
text messages (MT).
(1)Altimeter settings are usually trans-
mitted automatically when a CPDLC session andeligibility has been established with an aircraft. A
controller may also manually send an altimeter
setting message.
NOTE−
When conducting instrument approach procedures, pilots
are responsible to obtain and use the appr opriate altimeter
setting in accordance with 14 CFR Section 97.20. CPDLC
issued altimeter settings are excluded for this purpose.
(2)Initial contact is a safety validation
transaction that compares a pilot’s initiated altitude
downlink message with an aircraft’s ATC host
computer stored altitude. If an altitude mismatch isdetected, the controller will verbally provide
corrective action.
(3)Transfer of communications automati-
cally establishes data link contact with a succeeding
sector.
(4)Menu text transmissions are scripted
nontrajectory altering uplink messages.
NOTE−
Initial use of CPDLC will be at the Miami Air Route T raffic
Control Center (ARTCC). Air carriers will be the firstusers. Subsequently, CPDLC will be made available to all
NAS users. Later versions will include trajectory altering
services and expanded clearance and advisory messagecapabilities.
b. ATC Frequency Change Procedures.
1.The following phraseology will be used by
controllers to effect a frequency change:
EXAMPLE −
(Aircraft identification) contact (facility name or location
name and terminal function) (frequency) at (time, fix, oraltitude).
NOTE−
Pilots are expected to maintain a listening watch on the
transferring controller’ s frequency until the time, fix, oraltitude specified. ATC will omit frequency changerestrictions whenever pilot compliance is expected uponreceipt.
AIM 10/12/17
5−3−2 En Route Procedures2.The following phraseology should be utilized
by pilots for establishing contact with the designated
facility:
(a)When operating in a radar environment:
On initial contact, the pilot should inform the
controller of the aircraft’s assigned altitude preceded
by the words “level,” or “climbing to,” or
“descending to,” as appropriate; and the aircraft’s
present vacating altitude, if applicable.
EXAMPLE −
1.(Name) CENTER, (aircraft identification), LEVEL
(altitude or flight level) .
2.(Name) CENTER, (aircraft identification), LEAVING
(exact altitude or flight level), CLIMBING TO OR
DESCENDING TO (altitude of flight level) .
NOTE−
Exact altitude or flight level means to the nearest 100 foot
increment. Exact altitude or flight level reports on initialcontact provide ATC with information required prior to
using Mode C altitude information for separation
purposes.
(b)When operating in a nonradar environ-
ment:
(1)On initial contact, the pilot should
inform the controller of the aircraft’s present position,
altitude and time estimate for the next reporting point.
EXAMPLE −
(Name) CENTER, (aircraft identification), (position),
(altitude), ESTIMATING (reporting point) AT (time) .
(2)After initial contact, when a position
report will be made, the pilot should give the
controller a complete position report.
EXAMPLE −
(Name) CENTER, (aircraft identification), (position),
(time), (altitude), (type of flight plan), (ETA and name of
next reporting point), (the name of the next succeeding
reporting point), AND (remarks) .
REFERENCE −
AIM, Paragraph 5 −3−2 , Position Reporting
3.At times controllers will ask pilots to verify
that they are at a particular altitude. The phraseology
used will be: “VERIFY AT (altitude).” In climbing or
descending situations, controllers may ask pilots to
“VERIFY ASSIGNED ALTITUDE AS (altitude) .”
Pilots should confirm that they are at the altitudestated by the controller or that the assigned altitude is
correct as stated. If this is not the case, they should
inform the controller of the actual altitude being
maintained or the different assigned altitude.
CAUTION −
Pilots should not take action to change their actualaltitude or dif ferent assigned altitude to the altitude stated
in the controllers verification request unless the
controller specifically authorizes a change.
c. ARTCC Radio Frequency Outage. ARTCCs
normally have at least one back-up radio receiver and
transmitter system for each frequency, which can
usually be placed into service quickly with little or no
disruption of ATC service. Occasionally, technical
problems may cause a delay but switchover seldom
takes more than 60 seconds. When it appears that the
outage will not be quickly remedied, the ARTCC will
usually request a nearby aircraft, if there is one, to
switch to the affected frequency to broadcastcommunications instructions. It is important, there-
fore, that the pilot wait at least 1 minute before
deciding that the ARTCC has actually experienced aradio frequency failure. When such an outage does
occur, the pilot should, if workload and equipment
capability permit, maintain a listening watch on theaffected frequency while attempting to comply with
the following recommended communications
procedures:
1.If two-way communications cannot be
established with the ARTCC aft er changing frequen-
cies, a pilot should attempt to recontact the
transferring controller for the assignment of analternative frequency or other instructions.
2.When an ARTCC radio frequency failure
occurs after two-way communications have been
established, the pilot should attempt to reestablishcontact with the center on any other known ARTCC
frequency, preferably that of the next responsible
sector when practicable, and ask for instructions.However, when the next normal frequency change
along the route is known to involve another ATC
facility, the pilot should contact that facility, iffeasible, for instructions. If communications cannot
be reestablished by either method, the pilot is
expected to request communications instructions
from the FSS appropriate to the route of flight.
AIM 10/12/17
5−3−3 En Route ProceduresNOTE−
The exchange of information between an aircraft and anARTCC thr ough an FSS is quicker than relay via company
radio because the FSS has direct interphone lines to the
responsible ARTCC sector. Accordingly, when circum-
stances dictate a choice between the two, during anARTCC frequency outage, relay via FSS radio isrecommended.
5−3−2. Position Reporting
The safety and effectiveness of traffic control
depends to a large extent on accurate positionreporting. In order to provide the proper separation
and expedite aircraft movements, ATC must be able
to make accurate estimates of the progress of every
aircraft operating on an IFR flight plan.
a. Position Identification.
1.When a position report is to be made passing
a VOR radio facility, the time reported should be the
time at which the first complete reversal of the“to/from” indicator is accomplished.
2.When a position report is made passing a
facility by means of an airborne ADF, the timereported should be the time at which the indicator
makes a complete reversal.
3.When an aural or a light panel indication is
used to determine the time passing a reporting point,
such as a fan marker, Z marker, cone of silence or
intersection of range courses, the time should benoted when the signal is first received and again when
it ceases. The mean of these two times should then be
taken as the actual time over the fix.
4.If a position is given with respect to distance
and direction from a reporting point, the distance and
direction should be computed as accurately aspossible.
5.Except for terminal area transition purposes,
position reports or navigation with reference to aidsnot established for use in the structure in which flight
is being conducted will not normally be required by
ATC.
b. Position Reporting Points. CFRs require
pilots to maintain a listening watch on the appropriate
frequency and, unless operating under the provisions
of subparagraph c, to furnish position reports passing
certain reporting points. Reporting points are
indicated by symbols on en route charts. Thedesignated compulsory reporting point symbol is a
solid triangle
and the “on request” reporting
point symbol is the open triangle
. Reports
passing an “on request” reporting point are only
necessary when requested by ATC.
c. Position Reporting Requirements.
1. Flights Along Airways or Routes. A
position report is required by all flights regardless of
altitude, including those operating in accordance with
an ATC clearance specifying “VFR−on−top,” over
each designated compulsory reporting point along the
route being flown.
2. Flights Along a Direct Route. Regardless
of the altitude or flight level being flown, including
flights operating in accordance with an ATC
clearance specifying “ VFR−on−top,” pilots must
report over each reporting point used in the flight plan
to define the route of flight.
3. Flights in a Radar Environment. When
informed by ATC that their aircraft are in “Radar
Contact,” pilots should discontinue position reportsover designated reporting points. They should
resume normal position reporting when ATC advises
“RADAR CONTACT LOST” or “ RADAR SERVICE
TERMINATED.”
4. Flights in an Oceanic (Non-radar) Envir-
onment. Pilots must report over each point used in
the flight plan to define the route of flight, even if the
point is depicted on aeronautical charts as an “onrequest” (non-compulsory) reporting point. For
aircraft providing automatic position reporting via an
Automatic Dependent Surveillance-Contract(ADS-C) logon, pilots should discontinue voice
position reports.
NOTE−
ATC will inform pilots that they are in “radar contact”:
(a) when their aircraft is initially identified in the ATC
system; and
(b) when radar identification is reestablished after
radar service has been terminated or radar contact lost.Subsequent to being advised that the controller hasestablished radar contact, this fact will not be repeated to
the pilot when handed off to another controller. At times,
the aircraft identity will be confirmed by the receiving
controller; however, this should not be construed to meanthat radar contact has been lost. The identity oftransponder equipped air craft will be confirmed by asking
the pilot to “ident,” “squawk standby,” or to change codes.
Aircraft without transponders will be advised of theirposition to confirm identity. In this case, the pilot is
AIM 10/12/17
5−3−4 En Route Proceduresexpected to advise the controller if in disagreement with the
position given. Any pilot who cannot confirm the accuracy
of the position given because of not being tuned to theNAVAID referenced by the controller, should ask for
another radar position relative to the tuned in NAVAID.
d. Position Report Items:
1. Position reports should include the follow-
ing items:
(a)Identification;
(b)Position;
(c)Time;
(d)Altitude or flight level (include actual
altitude or flight level when operating on a clearance
specifying VFR −on−top);
(e)Type of flight plan (not required in IFR
position reports made directly to ARTCCs orapproach control);
(f)ETA and name of next reporting point;
(g)The name only of the next succeeding
reporting point along the route of flight; and
(h)Pertinent remarks.
5−3−3. Additional Reports
a. The following reports should be made to
ATC or FSS facilities without a specific ATC
request:
1.At all times.
(a)When vacating any previously assigned
altitude or flight level for a newly ass igned altitude or
flight level.
(b)When an altitude change will be made if
operating on a clearance specifying VFR −on−top.
(c)When unable to climb/descend at a rate of
a least 500 feet per minute.
(d)When approach has been missed.
(Request clearance for specific action; i.e., to
alternative airport, another approach, etc.)
(e)Change in the average true airspeed (at
cruising altitude) when it varies by 5 percent or
10 knots (whichever is greater) from that filed in the
flight plan.
(f)The time and altitude or flight level upon
reaching a holding fix or point to which cleared.(g)When leaving any assigned holding fix or
point.
NOTE−
The reports in subparagraphs (f) and (g) may be omitted by
pilots of air craft involved in instrument training at military
terminal area facilities when radar service is beingprovided.
(h)Any loss, in controlled airspace, of VOR,
TACAN, ADF, low frequency navigation receiver
capability, GPS anomalies while using installed
IFR−certified GPS/GNSS receivers, complete or
partial loss of ILS receiver capability or impairmentof air/ground communications capability. Reports
should include aircraft identification, equipment
affected, degree to which the capability to operateunder IFR in the ATC system is impaired, and the
nature and extent of assistance desired from ATC.
NOTE−
1.Other equipment installed in an aircraft may effectively
impair safety and/or the ability to operate under IFR. If
such equipment (e.g., airborne weather radar) malfunc-
tions and in the pilot’ s judgment either safety or IFRcapabilities are affected, reports should be made as above.
2.When reporting GPS anomalies, include the location
and altitude of the anomaly. Be specific when describingthe location and include duration of the anomaly if
necessary.
(i)Any information relating to the safety of
flight.
2. When not in radar contact.
(a)When leaving final approach fix inbound
on final approach (nonprecision approach) or whenleaving the outer marker or fix used in lieu of the outer
marker inbound on final approach (precision
approach).
(b)A corrected estimate at anytime it
becomes apparent that an estimate as previously
submitted is in error in excess of 2 minutes. For
flights in the North Atlantic (NAT), a revisedestimate is required if the error is 3 minutes or more.
b.Pilots encountering weather conditions which
have not been forecast, or hazardous conditions
which have been forecast, are expected to forward areport of such weather to ATC.
REFERENCE −
AIM, Paragraph 7 −1−20 , Pilot Weather Reports (PIREPs)
14 CFR Section 91.183(B) and (C).
AIM 10/12/17
5−3−5 En Route Procedures5−3−4. Airways and Route Systems
a.Three fixed route systems are established for air
navigation purposes. They are the Federal airwaysystem (consisting of VOR and L/MF routes), the jet
route system, and the RNA V route system. To the
extent possible, these route systems are aligned in an
overlying manner to facilitate transition between
each.
1.The VOR and L/MF (nondirectional radio
beacons) Airway System consists of airways
designated from 1,200 feet above the surface (or insome instances higher) up to but not including 18,000
feet MSL. These airways are depicted on IFR Enroute
Low Altitude Charts.
NOTE−
The altitude limits of a victor airway should not beexceeded except to effect transition within or between r oute
structures.
(a)Except in Alaska, the VOR airways are:
predicated solely on VOR or VORTAC navigation
aids; depicted in black on aeronautical charts; and
identified by a “V” (Victor) followed by the airwaynumber (for example, V12).
NOTE−
Segments of VOR airways in Alaska are based on L/MF
navigation aids and charted in brown instead of black onen route charts.
(1)A segment of an airway which is
common to two or more routes carries the numbers of
all the airways which coincide for that segment.When such is the case, pilots filing a flight plan need
to indicate only that airway number for the route filed.
NOTE−
A pilot who intends to make an airway flight, using VORfacilities, will simply specify the appropriate “victor”airway(s) in the flight plan. For example, if a flight is to be
made from Chicago to New Orleans at 8,000 feet, using
omniranges only, the route may be indicated as “departing
from Chicago −Midway, cruising 8,000 feet via Victor 9 to
Moisant International.” If flight is to be conducted in part
by means of L/MF navigation aids and in part on
omniranges, specifications of the appropriate airways in
the flight plan will indicate which types of facilities will beused along the described routes, and, for IFR flight, permit
ATC to issue a traffic clearance accordingly. A route mayalso be described by specifying the station over which the
flight will pass, but in this case since many VORs and L/MF
aids have the same name, the pilot must be careful toindicate which aid will be used at a particular location.This will be indicated in the route of flight portion of the
flight plan by specifying the type of facility to be used after
the location name in the following manner: Newark L/MF ,Allentown VOR.
(2)With respect to position reporting,
reporting points are designated for VOR Airway
Systems. Flights using Victor Airways will report
over these points unless advised otherwise by ATC.
(b)The L/MF airways (colored airways) are
predicated solely on L/MF navigation aids and are
depicted in brown on aeronautical charts and areidentified by color name and number (e.g., Amber
One). Green and Red airways are plotted east and
west. Amber and Blue airways are plotted north andsouth.
NOTE−
Except for G13 in North Ca rolina, the colored airway
system exists only in the state of Alaska. All other suchairways formerly so designated in the conterminous U.S.have been rescinded.
(c)The use of TSO −C145 (as revised) or
TSO−C146 (as revised) GPS/WAAS navigation
systems is allowed in Alaska as the only means of
navigation on published air traffic service (ATS)routes, including those V ictor, T−Routes, and colored
airway segments designated with a second minimum
en route altitude (MEA) depicted in blue andfollowed by the letter G at those lower altitudes. The
altitudes so depicted are below the minimum
reception altitude (MRA) of the land −based
navigation facility defining the route segment, and
guarantee standard en route obstacle clearance andtwo−way communications. Air carrier operators
requiring operations specifications are authorized to
conduct operations on those routes in accordancewith FAA operations specifications.
2.The jet route system consists of jet routes
established from 18,000 feet MSL to FL 450
inclusive.
(a)These routes are depicted on Enroute
High Altitude Charts. Jet routes are depicted in black
on aeronautical charts and are identified by a “J” (Jet)followed by the airway number (e.g., J12). Jet routes,
as VOR airways, are predicated solely on VOR or
VORTAC navigation facilities (except in Alaska).
NOTE−
Segments of jet routes in Alaska are based on L/MF
navigation aids and are charted in brown color instead of
black on en route charts.
AIM 10/12/17
5−3−6 En Route Procedures(b)With respect to position reporting,
reporting points are designated for jet route systems.
Flights using jet routes will report over these points
unless otherwise advised by ATC.
3. Area Navigation (RNA V) Routes.
(a)Published RNA V routes, including
Q−Routes and T−Routes, can be flight planned for
use by aircraft with RNA V capability, subject to anylimitations or requirements noted on en route charts,
in applicable Advisory Circulars, or by NOTAM.
RNA V routes are depicted in blue on aeronauticalcharts and are identified by the letter “Q” or “T”
followed by the airway numbe r (for example, Q −13,
T−205). Published RNA V routes are RNA V −2 except
when specifically charted as RNA V −1. These routes
require system performance currently met by GPS,
GPS/WAAS, or DME/DME/IRU RNA V systems that
satisfy the criteria discussed in AC 90 −100A, U.S.
Terminal and En Route Area Navigation (RNA V)
Operations.
NOTE−
AC 90−100A does not apply to over water RNAV routes
(reference 14 CFR 91.511, including the Q −routes in the
Gulf of Mexico and the Atlantic routes) or AlaskaVOR/DME RNAV r outes (“JxxxR”). The AC does not apply
to off−route RNAV operations, Alaska GPS routes or
Caribbean routes.
(1)Q−routes are available for use by RNA V
equipped aircraft between 18,000 feet MSL and
FL 450 inclusive. Q −routes are depicted on Enroute
High Altitude Charts.
NOTE−
Aircraft in Alaska may only operate on GNSS Q-routes
with GPS (TSO-C129 (as revised) or TSO-C196 (as
revised)) equipment while the aircraft remains in AirTraffic Control (ATC) radar surveillance or withGPS/WAAS which does not require ATC radar surveil-lance.
(2)T−routes are available for use by GPS or
GPS/WAAS equipped aircraft from 1,200 feet above
the surface (or in some instances higher) up to but not
including 18,000 feet MSL. T −routes are depicted on
Enroute Low Altitude Charts.
NOTE−
Aircraft in Alaska may only operate on GNSS T-routes
with GPS/WAAS (TSO-C145 (as r evised) or TSO-C146 (as
revised)) equipment.(b)Unpublished RNA V routes are direct
routes, based on area navigation capability, between
waypoints defined in terms of latitude/longitude
coordinates, degree −distance fixes, or offsets from
established routes/airways at a specified distance and
direction. Radar monitoring by ATC is required on all
unpublished RNA V routes, except for GNSS −
equipped aircraft cleared via filed publishedwaypoints recallable from the aircraft’s navigation
database.
(c)Magnetic Reference Bearing (MRB) is the
published bearing between two waypoints on an
RNA V/GPS/GNSS route. The MRB is calculated by
applying magnetic variation at the waypoint to the
calculated true course between two waypoints. The
MRB enhances situational awareness by indicating a
reference bearing (no −wind heading) that a pilot
should see on the compass/HSI/RMI, etc., when
turning prior to/over a waypoint en route to anotherwaypoint. Pilots should use this bearing as a reference
only, because their RNA V/GPS/GNSS navigation
system will fly the true course between the
waypoints.
b.Operation above FL 450 may be conducted on
a point-to-point basis. Navigational guidance is
provided on an area basis utilizing those facilitiesdepicted on the enroute high altitude charts.
c. Radar Vectors. Controllers may vector air-
craft within controlled airspace for separation
purposes, noise abatement considerations, when an
operational advantage will be realized by the pilot or
the controller, or when requested by the pilot. V ectors
outside of controlled airspace will be provided only
on pilot request. Pilots will be advised as to what thevector is to achieve when the vector is controller
initiated and will take the aircraft off a previously
assigned nonradar route. To the extent possible,
aircraft operating on RNA V routes will be allowed to
remain on their own navigation.
d.When flying in Canadian airspace, pilots are
cautioned to review Canadian Air Regulations.
1.Special attention should be given to the parts
which differ from U.S. CFRs.
(a)The Canadian Airways Class B airspace
restriction is an example. Class B airspace is allcontrolled low level airspace above 12,500 feet MSL
or the MEA, whichever is higher, within which only
IFR and controlled VFR flights are permitted. (Low
AIM 10/12/17
5−3−7 En Route Procedureslevel airspace means an airspace designated and
defined as such in the Designated Airspace
Handbook.)
(b)Unless issued a VFR flight clearance by
ATC, regardless of the weather conditions or the
height of the terrain, no person may operate an
aircraft under VMC within Class B airspace.
(c)The requirement for entry into Class Bairspace is a student pilot permit (under the guidance
or control of a flight instructor).
(d)VFR flight requires visual contact with
the ground or water at all times.
2.Segments of VOR airways and high level
routes in Canada are based on L/MF navigation aids
and are charted in brown color instead of blue on
en route charts.
FIG 5−3−1
Adhering to Airways or Routes
5−3−5. Airway or Route Course Changes
a.Pilots of aircraft are required to adhere to
airways or routes being flown. Special attention must
be given to this requirement during course changes.
Each course change consists of variables that make
the technique applicable in each case a matter only thepilot can resolve. Some variables which must be
considered are turn radius, wind effect, airspeed,
degree of turn, and cockpit instrumentation. An early
turn, as illustrated below, is one method of adhering
to airways or routes. The use of any available cockpitinstrumentation, such as Distance Measuring Equip-
ment, may be used by the pilot to lead the turn when
making course changes. This is consistent with the
intent of 14 CFR Section 91.181, which requires
pilots to operate along the centerline of an airway and
along the direct course between navigational aids or
fixes.
b.Turns which begin at or after fix passage may
exceed airway or route boundaries. FIG 5−3−1
contains an example flight track depicting this,
together with an example of an early turn.
AIM 10/12/17
5−3−8 En Route Proceduresc.Without such actions as leading a turn, aircraft
operating in excess of 290 knots true air speed (TAS)
can exceed the normal airway or route boundaries
depending on the amount of course change required,
wind direction and velocity, the character of the turnfix (DME, overhead navigation aid, or intersection),
and the pilot’s technique in making a course change.
For example, a flight operating at 17,000 feet MSLwith a TAS of 400 knots, a 25 degree bank, and a
course change of more than 40 degrees would exceed
the width of the airway or route; i.e., 4 nautical mileseach side of centerline. However, in the airspace
below 18,000 feet MSL, operations in excess of
290 knots TAS are not prevalent and the provision of
additional IFR separation in all course change
situations for the occasional aircraft making a turn in
excess of 290 knots TAS creates an unacceptablewaste of airspace and imposes a penalty upon the
preponderance of traffic which operate at low speeds.
Consequently, the FAA expects pilots to lead turnsand take other actions they consider necessary during
course changes to adhere as closely as possible to the
airways or route being flown.
5−3−6. Changeover Points (COPs)
a.COPs are prescribed for Federal airways, jet
routes, area navigation routes, or other direct routes
for which an MEA is designated under 14 CFRPart 95. The COP is a point along the route or airway
segment between two adjacent navigation facilities or
waypoints where changeover in navigation guidance
should occur. At this point, the pilot should change
navigation receiver frequency from the station
behind the aircraft to the station ahead.
b.The COP is normally located midway between
the navigation facilities for straight route segments,or at the intersection of radials or courses forming a
dogleg in the case of dogleg route segments. When
the COP is NOT located at the midway point,aeronautical charts will depict the COP location and
give the mileage to the radio aids.
c.COPs are established for the purpose of
preventing loss of navigation guidance, to prevent
frequency interference from other facilities, and toprevent use of dif ferent facilities by different aircraft
in the same airspace. Pilots are urged to observe COPs
to the fullest extent.5−3−7. Minimum Turning Altitude (MTA)
Due to increased airspeeds at 10,000 ft MSL or above,
the published minimum enroute altitude (MEA) may
not be sufficient for obstacle clearance when a turn is
required over a fix, NA V AID, or waypoint. In theseinstances, an expanded area in the vicinity of the turn
point is examined to determine whether the published
MEA is sufficient for obstacle clearance. In somelocations (normally mountainous), terrain/obstacles
in the expanded search area may necessitate a higher
minimum altitude while conducting the turningmaneuver. T urning fixes requiring a higher minimum
turning altitude (MTA) will be denoted on
government charts by the minimum crossing altitude
(MCA) icon (“x” flag) and an accompanying note
describing the MTA restriction. An MTA restriction
will normally consist of the air traffic service (ATS)route leading to the turn point, the ATS route leading
from the turn point, and the required altitude; e.g.,
MTA V330 E TO V520 W 16000. When an MTA isapplicable for the intended route of flight, pilots must
ensure they are at or above the charted MTA not later
than the turn point and maintain at or above the MTAuntil joining the centerline of the A TS route following
the turn point. Once established on the centerline
following the turning fix, the MEA/MOCA determ-
ines the minimum altitude available for assignment.
An MTA may also preclude the use of a specificaltitude or a range of altitudes during a turn. For
example, the MTA may restrict the use of 10,000
through 11,000 ft MSL. In this case, any altitudegreater than 11,000 ft MSL is unrestricted, as are
altitudes less than 10,000 ft MSL provided
MEA/MOCA requirements are satisfied.
5−3−8. Holding
a.Whenever an aircraft is cleared to a fix other
than the destination airport and delay is expected, it
is the responsibility of ATC to issue complete holding
instructions (unless the pattern is charted), an EFC
time and best estimate of any additional en
route/terminal delay.
NOTE−
Only those holding patterns depicted on U.S. government
or commercially produced (meeting F AA requirements)
low/high altitude en route, and area or STAR charts should
be used.
b.If the holding pattern is charted and the
controller doesn’t issue complete holding instruc-
tions, the pilot is expected to hold as depicted on the
AIM 10/12/17
5−3−9 En Route Proceduresappropriate chart. When the pattern is charted on the
assigned procedure or route being flown, ATC may
omit all holding instructions except the charted
holding direction and the statement AS PUBLISHED;
for example, HOLD EAST AS PUBLISHED. ATC
must always issue complete holding instructions
when pilots request them.
c.If no holding pattern is charted and holding
instructions have not been issued, the pilot should ask
ATC for holding instructions prior to reaching the fix.
This procedure will eliminate the possibility of an
aircraft entering a holding pattern other than thatdesired by ATC. If unable to obtain holding
instructions prior to reaching the fix (due to
frequency congestion, stuck microphone, etc.), thenenter a standard pattern on the course on which the
aircraft approached the fix and request further
clearance as soon as possible. In this event, thealtitude/flight level of the aircraft at the clearance
limit will be protected so that separation will be
provided as required.
d.When an aircraft is 3 minutes or less from a
clearance limit and a clearance beyond the fix has not
been received, the pilot is expected to start a speed
reduction so that the aircraft will cross the fix,initially, at or below the maximum holding airspeed.
e.When no delay is expected, the controller
should issue a clearance beyond the fix as soon as
possible and, whenever possible, at least 5 minutesbefore the aircraft reaches the clearance limit.
f.Pilots should report to ATC the time and
altitude/flight level at which the aircraft reaches the
clearance limit and report leaving the clearance limit.
NOTE−
In the event of two-way communications failure, pilots are
required to comply with 14 CFR Section 91.185.
g.When holding at a VOR station, pilots should
begin the turn to the outbound leg at the time of the
first complete reversal of the to/from indicator.h.Patterns at the most generally used holding
fixes are depicted (charted) on U.S. Government or
commercially pr oduced (meetin g FAA requirements)
Low or High Altitude En Route, Area, Departure
Procedure, and STAR Charts. Pilots are expected tohold in the pattern depicted unless specifically
advised otherwise by ATC.
NOTE−
Holding patterns that protect for a maximum holding
airspeed other than the standard may be depicted by an
icon, unless otherwise depicted. The icon is a standardholding pattern symbol (racetrack) with the airspeedrestriction shown in the center. In other cases, the airspeed
restriction will be depicted next to the standard holding
pattern symbol.
REFERENCE −
AIM, Paragraph 5 −3−8 j2, Holding
i.An ATC clearance requiring an aircraft to hold
at a fix where the pattern is not charted will includethe following information: (See FIG 5−3−2.)
1.Direction of holding from the fix in terms of
the eight cardinal compass points (i.e., N, NE, E, SE,
etc.).
2.Holding fix (the fix may be omitted if
included at the beginning of the transmission as the
clearance limit).
3.Radial, course, bearing, airway or route on
which the aircraft is to hold.
4.Leg length in miles if DME or RNA V is to be
used (leg length will be specified in minutes on pilot
request or if the controller considers it necessary).
5.Direction of turn if left turns are to be made,
the pilot requests, or the controller considers it
necessary.
6.Time to expect further clearance and any
pertinent additional delay information.
AIM 10/12/17
5−3−10 En Route ProceduresFIG 5−3−2
Holding Patterns
TYPICAL PROCEDURE ON AN ILS OUTER MARKERTYPICAL PROCEDURE ON AN ILS OUTER MARKEREXAMPLES OF HOLDINGEXA MPLES OF HOLDING
L OMOMM MM M
RUNWAYRUNWAY
VORVORVORVOR
TYPICAL PROCEDURE AT INTERSECTIONTYPICAL PROCEDURE AT INTERSECTION
OF VOR RADIALSOF VOR RADIALS
HOLDING COURSE
AWAY FROM NAVAIDHOLDING COURSE
AWAY FROM NAVAIDHOLDING COURSETOWARD NAVAIDHOLDING COURSE
TOWARD NAVAID
VORTACVORTAC
15 NM DME FIX15 NM DME FIX 10 NM DME FIX10 NM DME FIX
TYPICAL PROCEDURE AT DME FIXTY PICA L PROCEDURE AT DME FIX
AIM 10/12/17
5−3−11 En Route ProceduresFIG 5−3−3
Holding Pattern Descriptive Terms
ABEAMABEAM
HOLDING SIDEHOLDING SIDE
OUTBOUND
ENDOUTBOUND
END
HOLDING
COURSEHOLDING
COURSEOUTBOUNDOUTBOUND
INBOUNDINBOUND
NONHOLDING SIDENONHOLDING SIDEFIX ENDFIX END
RECIPROCALRECIPROCAL
FIXFIX
j.Holding pattern airspace protection is based on
the following procedures.
1. Descriptive Terms.
(a) Standard Pattern. Right turns
(See FIG 5−3−3.)
(b) Nonstandard Pattern. Left turns
2. Airspeeds.
(a)All aircraft may hold at the following
altitudes and maximum holding airspeeds:
TBL 5−3−1
Altitude (MSL) Airspeed (KIAS)
MHA − 6,000’ 200
6,001’ − 14,000’ 230
14,001’ and above 265
NOTE−
These are the maximum indicated air speeds applicable to
all holding.
(b)The following are exceptions to the
maximum holding airspeeds:
(1)Holding patterns from 6,001’ to
14,000’ may be restricted to a maximum airspeed of
210 KIAS. This nonstandard pattern will be depictedby an icon.
(2)Holding patterns may be restricted to a
maximum speed. The speed restriction is depicted in
parenthesis inside the holding pattern on the chart:
e.g., (175). The aircraft should be at or below themaximum speed prior to initially crossing the holdingfix to avoid exiting the protected airspace. Pilots
unable to comply with the maximum airspeed
restriction should notify ATC.
(3)Holding patterns at USAF airfields
only− 310 KIAS maximum, unless otherwise
depicted.
(4)Holding patterns at Navy fields only −
230 KIAS maximum, unless otherwise depicted.
(5)All helicopter/power lift aircraft hold-
ing on a “COPTER” instrument procedure is
predicated on a minimum airspeed of 90 KIAS unless
charted otherwise.
(6)When a climb −in hold is specified by a
published procedure (for example, “Climb −in
holding pattern to depart XYZ VORTAC at or above
10,000.” or “All aircraft climb −in TRUCK holding
pattern to cross TRUCK Int at or above 1 1,500 before
proceeding on course.”), additional obstacle protec-tion area has been provided to allow for greater
airspeeds in the climb for those aircraft requiring
them. A maximum airspeed of 310 KIAS is permitted
in Climb −in−holding, unless a maximum holding
airspeed is published, in which case that maximum
airspeed is applicable. The airspeed limitations in 14
CFR Section 91.117, Aircraft Speed, still apply.
(c)The following phraseology may be used
by an A TCS to advise a pilot of the maximum holding
airspeed for a holding pattern airspace area.
PHRASEOLOGY −
(AIRCRAFT IDENTIFICATION) (holding instructions,when needed) MAXIMUM HOLDING AIRSPEED IS(speed in knots).
AIM 10/12/17
5−3−12 En Route ProceduresFIG 5−3−4
Holding Pattern Entry Procedures
3. Entry Procedures. Holding protected
airspace is designed based in part on pilot compliance
with the three recommended holding pattern entry
procedures discussed below. Deviations from these
recommendations, coupled with excessive airspeedcrossing the holding fix, may in some cases result in
the aircraft exceeding holding protected airspace.
(See FIG 5−3−4.)
(a) Parallel Procedure. When approaching
the holding fix from anywhere in sector (a), the
parallel entry procedure would be to turn to a heading
to parallel the holding course outbound on thenonholding side for one minute, turn in the direction
of the holding pattern through more than 180 degrees,
and return to the holding fix or intercept the holding
course inbound.
(b) Teardrop Procedure. When approach-
ing the holding fix from anywhere in sector (b), theteardrop entry procedure would be to fly to the fix,
turn outbound to a heading for a 30 degree teardrop
entry within the pattern (on the holding side) for aperiod of one minute, then turn in the direction of the
holding pattern to intercept the inbound holding
course.
(c) Direct Entry Procedure. When ap-
proaching the holding fix from anywhere in
sector (c), the direct entry procedure would be to flydirectly to the fix and turn to follow the holding
pattern.
(d)While other entry procedures may enable
the aircraft to enter the holding pattern and remain
within protected airspace, the parallel, teardrop and
direct entries are the procedures for entry and holding
recommended by the FAA, and were derived as part
of the development of the size and shape of the
obstacle protection areas for holding.
(e) Nonstandard Holding Pattern. Fix end
and outbound end turns are made to the left. Entry
procedures to a nonstandard pattern are oriented in
relation to the 70 degree line on the holding side just
as in the standard pattern.
4. Timing.
(a) Inbound Leg.
(1)At or below 14,000 feet MSL: 1 minute.
(2)Above 14,000 feet MSL: 1
1/2 minutes.
NOTE−
The initial outbound leg should be flown for 1 minute or1
1/2 minutes (appropriate to altitude). Timing for
subsequent outbound legs should be adjusted, asnecessary, to achieve proper inbound leg time. Pilots may
use any navigational means available; i.e., DME, RNAV ,
etc., to ensure the appropriate inbound leg times.
(b) Outbound leg timing begins over/abeam
the fix, whichever occurs later. If the abeam position
AIM 10/12/17
5−3−13 En Route Procedurescannot be determined, start timing when turn to
outbound is completed.
5. Distance Measuring Equipment (DME)/
GPS Along −Track Distance (ATD). DME/GPS
holding is subject to the same entry and holding
procedures except that distances (nautical miles) areused in lieu of time values. The outbound course of
the DME/GPS holding pattern is called the outbound
leg of the pattern. The controller or the instrumentapproach procedure chart will specify the length of
the outbound leg. The end of the outbound leg is
determined by the DME or ATD readout. The holding
fix on conventional procedures, or controller definedholding based on a conventional navigation aid with
DME, is a specified course or radial and distances are
from the DME station for both the inbound and
outbound ends of the holding pattern. When flying
published GPS overlay or stand alone procedureswith distance specified, the holding fix will be a
waypoint in the database and the end of the outbound
leg will be determined by the ATD. Some GPSoverlay and early stand alone procedures may have
timing specified. (See FIG 5 −3−5, FIG 5−3−6 and
FIG 5−3−7.) See Paragraph 1 −1−17, Global Position-
ing System (GPS), for requirements and restriction
on using GPS for IFR operations.
FIG 5−3−5
Inbound Toward NA V AID
NOTE−
When the inbound course is toward the NAVAID, the fix distance is 10 NM, and the leg length is 5 NM, then the end of theoutbound leg will be reached when the DME reads 15 NM.
FIG 5−3−6
Inbound Leg Away from NA V AID
NOTE−
When the inbound course is away from the NAVAID and the fix distance is 28 NM, and the leg length is 8 NM, then the end
of the outbound leg will be reached when the DME reads 20 NM.
AIM 10/12/17
5−3−14 En Route Procedures6. Use of RNA V Distance in lieu of DME
Distance. Substitution of RNA V computed distance
to or from a NA V AID in place of DME distance is
permitted when hol ding. However, the actual holding
location and pattern flown will be further from theNAVAID than designed due to the lack of slant range
in the position solution (see FIG 5−3−7). This may
result in a slight difference between RNA V distancereadout in reference to the NA V AID and the DMEreadout, especially at higher altitudes. When used
solely for DME substitution, the difference between
RNA V distance to/from a fix and DME slant range
distance can be considered negligible and no pilot
action is required.
REFERENCE −
AIM Paragraph 1 −2−3, Use of Suitable Ar ea Navigation (RNAV) Systems
on Conventional Procedures and Routes
FIG 5−3−7
Difference Between DME Distance From NA V AID & RNA V Computed Distance From NA V AID
7. Use of RNA V Guidance and Holding.
RNA V systems, including multi −sensor Flight
Management Systems (FMS) and stand −alone GPS
receivers, may be used to furnish lateral guidance
when executing a hold. The manner in which holding
is implemented in an RNA V system varies widely
between aircraft and RNA V system manufacturers.
Holding pattern data may be extracted from theRNA V database for published holds or may be
manually entered for ad −hoc ATC−assigned holds.
Pilots are expected to be familiar with the capabilities
and limitations of the specific RNA V system used for
holding.
(a)All holding, including holding defined on
an RNA V or RNP procedure, is based on theconventional NA V AID holding design criteria,
including the holding protected airspace construc-
tion. There are dif ferences between the holding entry
and flight track assumed in conventional holding
pattern design and the entry and track that may be
flown when RNA V guidance is used to executeholding. Individually, these differences may not
affect the ability of the aircraft to remain within
holding pattern protected airspace. However, cumu-latively, they can result in deviations sufficient to
result in excursions up to limits of the holding pattern
protected airspace, and in some circumstances
beyond protected airspace. The following difference
and considerations apply when an RNA V systemfurnishes the lateral guidance used to fly a holding
pattern:
(1)Many systems use ground track angle
instead of heading to select the entry method. While
the holding pattern design allows a 5 degree
tolerance, this may result in an unexpected entry
when the winds induce a large drift angle.
(2)The holding protected airspace is based
on the assumption that the aircraft will fly −over the
holding fix upon initial entry. RNA V systems may
execute a “fly −by” turn when approaching the
holding fix prior to entry. A “fly −by” turn during a
direct entry from the holding pattern side of holding
course may result in excursions beyond protectedairspace, especially as the intercept angle and ground
speed increase.
(3)During holding, RNA V systems furnish
lateral steering guidance using either a constant bank
or constant radius to achieve the desired inbound and
AIM 10/12/17
5−3−15 En Route Proceduresoutbound turns. An aircraft’s flight guidance system
may use reduced bank angles for all turns including
turns in holding, especially at higher altitudes, that
may result in exceeding holding protected airspace.
Use of a shallower bank angle will expand both thewidth and length of the aircraft track, especially as
wind speed increases. If the flight guidance system’s
bank angle limit feature is pilot −selectable, a
minimum 25 degree bank angle should be selected
regardless of altitude unless aircraft operating
limitations specify otherwise and the pilot advisesATC.
(4)Where a holding distance is published,
the turn from the outbound leg begins at the published
distance from the holding fix, thus establishing thedesign turn point required to remain within protected
airspace. RNA V systems apply a database coded or
pilot−entered leg distance as a maximum length of the
inbound leg to the holding fix. The RNA V system
then calculates a turn point from the outbound legrequired to achieve this inbound leg length. This often
results in an RNA V −calculated turn point on the
outbound leg beyond the design turn point. (SeeFIG 5−3−8). With a strong headwind against the
outbound leg, RNA V systems may fly up to and
possibly beyond the limits of protected airspacebefore turning inbound. (See FIG 5−3−9.) This is
especially t rue at higher altitudes where wind speeds
are greater and ground speed results in a widerholding pattern.
FIG 5−3−8
RNA V Lateral Guidance and Holding – No Wind
FIG 5−3−9
RNA V Lateral Guidance and Holding – Effect of Wind
AIM 10/12/17
5−3−16 En Route Procedures(5)Some RNA V systems compute the
holding pattern based on the aircraft’s altitude and
speed at a point prior to entering the hold. If the
indicated airspeed is not reduced to comply with the
maximum holding speed before this point, thecomputed pattern may exceed the protected airspace.
Loading or executing a holding pattern may result in
the speed and time limits applicable to the aircraft’scurrent altitude being used to define the holding
pattern for RNA V lateral guidance. This may result in
an incorrect hold being flown by the RNA V system.For example, entering or executing the holding
pattern above 14,000 feet when intending to hold
below 14,000 feet may result in applying 1 ½ minute
timing below 14,000 feet.
NOTE−
Some systems permit the pilot to modify leg time of holding
patterns defined in the navigation database; for example,
a hold−in−lieu of pr ocedure turn. In most RNAV systems,
the holding pattern time remains at the pilot −modified time
and will not revert back to the coded time if the aircraftdescends to a lower altitude where a shorter time interval
applies.
(b)RNA V systems are not able to alert the
pilot for excursions outside of holding pattern
protected airspace since the dimensions of thisairspace are not included in the navigation database.
In addition, the dimensions of holding pattern
protected airspace vary with altitude for a chartedholding pattern, even when the hold is used for the
same application. Close adherence to the pilot actions
described in this section reduce the likelihood ofexceeding the boundary of holding pattern protected
airspace when using RNA V lateral guidance to
conduct holding.
(c)Holding patterns may be stored in the
RNA V system’s navigation database and includecoding with parameters defining how the RNA V
system will conduct the hold. For example, coding
will determine whether holding is conducted tomanual termination (HM), continued holding until
the aircraft reaches a specified altitude (HA), or
holding is conducted until the holding fix is crossedthe first time after entry (HF). Some systems do not
store all holding patterns, and may only store patterns
associated with missed approaches and hold −in−lieu
of procedure turn (HILPT). Some store all holding as
standard patterns and require pilot action to conduct
non−standard holding (left turns).(1)Pilots are cautioned that multiple
holding patterns may be established at the same fix.
These holding patterns may differ in respect to turn
directions and leg lengths depending on their
application as an en route holding pattern, a holdingpattern charted on a SID or STAR, or when used on
an instrument approach procedure. Many RNA V
systems limit the database coding at a particular fix to
a single holding pattern definition. Pilots extracting
the holding pattern from the navigation database are
responsible for confirming that the holding patternconforms to the assigned charted holding pattern in
terms of turn direction, speed limit, timing, and
distance.
(2)If ATC assigns holding that is not
charted, then the pilot is responsible for programming
the RNA V system with the assigned holding course,
turn direction, speed limit, leg length, or leg time.
(3)Changes made after the initial execu-
tion may not apply until the next circuit of the holding
pattern if the aircraft is in close proximity to the
holding fix.
8. Pilot Action. The following actions are
recommended to ensure that the aircraft remains
within holding protected airspace when holding isperformed using either conventional NA V AID
guidance or when using RNA V lateral guidance.
(a)Speed. When ATC furnishes advance
notice of holding, start speed reduction to be at or
below th e maximum holding speed allowed at least 3
minutes prior to crossing the holding fix. If advance
notice by A TC is not provided, begin speed reduction
as expeditiously as practical. It is acceptable to allow
RNAV systems to determine an appropriate decelera-
tion point prior to the holding fix and to manage thespeed reduction to the RNA V computed holding
speed. If the pilot does not permit the RNA V system
to manage the deceleration from the computed point,the actual hold pattern size at holding entry may differ
from the holding pattern size computed by the RNA V
system.
(1)Aircraft are expected to enter holding at
or below the maximum holding speed established inparagraph 5 −3−8 j 2(a) or the charted maximum
holding speed.
[a]All fixed wing aircraft conducting
holding should fly at speeds at or above 90 KIAS to
minimize the influence of wind drift.
AIM 10/12/17
5−3−17 En Route Procedures[b]When RNA V lateral guidance is used
in fixed wing airplanes, it is desirable to enter and
conduct holding at the lowest practical airspeed
consistent with the airplane’s recommended holding
speed to address the cumu lative errors associated
with RNA V holding and increase the probability of
remaining within protected airspace. It is acceptable
to allow RNA V systems to determine a recommended
holding speed that is at or below the maximum
holding speed.
[c]Helicopter holding is based on a
minimum airspeed of 90 KIAS.
(2)Advise ATC immediately if unable to
comply with the maximum holding airspeed and
request an alternate clearance.
NOTE−
Speeds above the maximum or published holding speedmay be necessary due to turbulence, icing, etc. Exceedingmaximum holding airspeed may result in aircraftexcursions beyond the holding pattern protected airspace.
In a non−radar envir onment, the pilot should advise ATC
that they cannot accept the assigned hold.
(3)Ensure the RNA V system applies the
proper time and speed restrictions to a holdingpattern. This is especially critical when climbing or
descending to a holding pattern altitude where time
and speed restrictions are different than at the presentaircraft altitude.
(b)Bank Angle. For holding not involving
the use of RNA V lateral guidance, make all turnsduring entry and while holding at:
(1)3 degrees per second, or
(2)30 degree bank angle, or
(3)25 degree bank angle, provided a flight
director system is used.
NOTE−
Use whichever requires the least bank angle.
(4)When using RNA V lateral guidance to
conduct holding, it is acceptable to permit the RNA V
system to calculate the appropriate bank angle for the
outbound and inbound turns. Do not use flight
guidance system bank angle limiting functions of less
than 25 degrees unless the feature is not pilot −se-
lectable, required by the aircraft limitations, or its use
is necessary to comply with the aircraft’s minimummaneuvering speed margins. If the bank angle must
be limited to less than 25 degrees, advise ATC that
additional area for holding is required.
(c)Compensate for wind effect primarily by
drift correction on the inbound and outbound legs.
When outbound, triple the inbound drift c orrection to
avoid major turning adjustments; for example, ifcorrecting left by 8 degrees when inbound, correct
right by 24 degrees when outbound.
(d)Determine entry turn from aircraft
heading upon arrival at the holding fix;
+/− 5 degrees
in heading is considered to be within allowable goodoperating limits for determining entry. When using
RNA V lateral guidance for holding, it is permissible
to allow the system to compute the holding entry.
(e)RNA V lateral guidance may execute a
fly−by turn beginning at an excessively lar ge distance
from the holding fix. Reducing speed to the
maximum holding speed at least 3 minutes prior to
reaching the holding fix and using the recommended
25 degree bank angle will reduce potential excursions
beyond protected airspace.
(f)When RNA V guidance is used for holding,
pilots sh ould be prepared to intervene if the turn from
outbound leg to the inbound leg does not begin within
a reasonable distance of the charted leg length,
especially when holding is used as a course reversalHILPT. Pilot intervention is not required when
holding in an ATC −assigned holding pattern that is
not charted. However , notify ATC when the outbound
leg length becomes excessive when RNA V guidance
is used for holding.
k.When holding at a fix and instructions are
received specifying the time of departure from the fix,
the pilot should adjust the aircraft’s flight path withinthe limits of the established holding pattern in order
to leave the fix at the exact time specified. After
departing the holding fix, normal speed is to beresumed with respect to other governing speed
requirements, such as terminal area speed limits,
specific A TC requests, etc. Where the fix is associated
with an instrument approach and timed approaches
are in effect, a procedure turn must not be executed
unless the pilot advises ATC, since aircraft holdingare expected to proceed inbound on final approach
directly from the holding pattern when approach
clearance is received.
AIM 10/12/17
5−3−18 En Route Proceduresl.Radar surveillance of holding pattern airspace
areas.
1.Whenever aircraft are holding, ATC will
usually provide radar surveillance of the holdingairspace on the controller’s radar display.
2.The controller will attempt to detect any
holding aircraft that stray outside the holding airspace
and will assist any detected aircraft to return to theassigned airspace.
NOTE−
Many factors could prevent ATC from providing thisadditional service, such as workload, number of targets,precipitation, ground clutter , and radar system capability.
These circumstances may make it unfeasible to maintain
radar identification of aircraft to detect aircraft strayingfrom the holding pattern. The provision of this servicedepends entirely upon whether controllers believe they are
in a position to provide it and does not relieve a pilot of their
responsibility to adhere to an accepted ATC clearance.
3.ATC is responsible for traffic and obstruction
separation when they have assigned holding that isnot associated with a published (charted) holding
pattern. Altitudes assigned will be at or above the
minimum vectoring or minimum IFR altitude.
4.If an aircraft is established in a published
holding pattern at an assigned altitude above the
published minimum holding altitude and subsequent-
ly cleared for the approach, the pilot may descend to
the published minimum holding altitude. The holding
pattern would only be a segment of the IAP if it is
published on the instrument procedure chart and is
used in lieu of a procedure turn.
m.For those holding patterns where there are no
published minimum holding altitudes, the pilot, upon
receiving an approach clearance, must maintain the
last assigned altitude until leaving the holding pattern
and established on the inbound course. Thereafter, the
published minimum altitude of the route segment
being flown will apply. It is expected that the pilot
will be assigned a holding altitude that will permit anormal descent on the inbound course.
AIM 10/12/17
5−4−1 Arrival ProceduresSection 4. Arrival Procedures
5−4−1. Standard Terminal Arrival (STAR)
Procedures
a.A STAR is an ATC coded IFR arrival route
established for application to arriving IFR aircraft
destined for certain airports. STARs simplifyclearance delivery procedures, and also facilitate
transition between en route and instrument approach
procedures.
1.STAR procedures may have mandatory
speeds and/or crossing altitudes published. OtherSTARs may have planning information depicted to
inform pilots what clearances or restrictions to
“expect .” “Expect ” altitudes/speeds are not consid-
ered STAR procedures crossing restrictions unless
verbally issued by ATC. Published speed restrictions
are independent of altitude restrictions and aremandatory unless modified by ATC. Pilots should
plan to cross waypoints with a published speed
restriction, at the published speed, and should notexceed this speed past the associated waypoint unless
authorized by ATC or a published note to do so.
NOTE−
The “ expect ” altitudes/speeds are published so that pilots
may have the information for planning purposes. Thesealtitudes/speeds must not be used in the event of lostcommunications unless ATC has specifically advised thepilot to expect these altitudes/speeds as part of a further
clearance.
REFERENCE −
14 CFR Section 91.185(c)(2)(iii).
2.Pilots navigating on STAR procedures must
maintain last assigned altitude until receiving
authorization to descend so as to comply with all
published/issued restrictions. This authorization may
contain the phraseology “DESCEND VIA.” If
vectored or cleared to deviate off of a STAR, pilots
must consider the STAR canceled, unless the
controller adds “expect to resume STAR;” pilots
should then be prepared to rejoin the STAR at asubsequent fix or procedure leg. If a descent
clearance has been received that included a crossing
restriction, pilots should expect the controller to issue
an altitude to maintain.
(a)Clearance to “descend via” authorizes
pilots to:(1)Descend at pilot’s discretion to meet
published restrictions and laterally navigate on a
STAR.
(2)When cleared to a waypoint depicted on
a STAR, to descend from a previously assigned alti-
tude at pilot’s discretion to the altitude depicted at that
waypoint.
(3)Once established on the depicted ar-
rival, to descend and to meet all published or assigned
altitude and/or speed restrictions.
NOTE−
1.When otherwise cleared along a route or pr ocedure that
contains published speed restrictions, the pilot must com-ply with those speed restrictions independent of anydescend via clearance.
2.ATC anticipates pilots will begin adjusting speed the
minimum distance necessary prior to a published speed
restriction so as to cross the waypoint/fix at the publishedspeed. Once at the published speed, ATC expects pilots will
maintain the published speed until additional adjustment
is required to comply with further published or ATCassigned speed restrictions or as required to ensure
compliance with 14 CFR Section 91.117.
3.The “descend via” is used in conjunction with STARs to
reduce phraseology by not requiring the controller torestate the altitude at the next waypoint/fix to which the
pilot has been cleared.
4.Air traffic will assign an altitude to cross the waypoint/
fix, if no altitude is depicted at the waypoint/fix, for air craft
on a direct routing to a STAR. Air traffic must ensure
obstacle clearance when issuing a “descend via”instruction to the pilot.
5.Minimum en route altitudes (MEA) are not considered
restrictions; however, pilots must r emain above all MEAs,
unless receiving an ATC instruction to descend below theMEA.
EXAMPLE −
1.Lateral/routing clearance only.
“Cleared Tyler One arrival.”
NOTE−
In Example 1, pilots are cleared to fly the lateral path of the
procedure. Compliance with any published speed restric-
tions is required. No descent is authorized.
2.Routing with assigned altitude.
“Cleared Tyler One arrival, descend and maintain
flight level two four zero.”
“Cleared T yler One arrival, descend at pilot’ s discre-
tion, maintain flight level two four zero.”
AIM 10/12/17
5−4−2 Arrival ProceduresNOTE−
In Example 2, the first clearance requires the pilot to des-cend to FL 240 as directed, comply with any publishedspeed restrictions, and maintain FL 240 until cleared for
further vertical navigation with a newly assigned altitude
or a“descend via” clearance. The second clearance authorizes the pilot to descend toFL 240 at his discretion, to comply with any published
speed restrictions, and then maintain FL 240 until issued
further instructions.
3.Lateral/routing and vertical navigation clearance.
“Descend via the Eagul Five arrival.”
“Descend via the Eagul Five arrival, except, cross
Vnnom at or above one two thousand.”
NOTE−
In Example 3, the first clearance authorized the aircraft todescend at pilot’ s discretion on the Eagul Five arrival; thepilot must descend so as to comply with all published alti-
tude and speed restrictions.
The second clearance authorizes the same, but r equires the
pilot to descend so as to cross at Vnnom at or above 12,000.
4.Lateral/routing and vertical navigation clearance
when assigning altitude not published on procedure.
“Descend via the Eagul Five arrival, except after
Geeno, maintain one zero thousand.”
“Descend via the Eagul Five arrival, except cross
Geeno at one one thousand th en maintain seven thou-
sand.”
NOTE−
In Example 4, the first clearance authorized the aircraft to
track laterally on the Eagul Five Arrival and to descend at
pilot’ s discretion so as to comply with all altitude and speed
restrictions until reaching Geeno and then maintain10,000. Upon reaching 10,000, aircraft should maintain10,000 until cleared by ATC to continue to descend.
The second clearance r equires the same, except the air craft
must cross Geeno at 1 1,000 and is then authorized to con-
tinue descent to and maintain 7,000.
5.Direct routing to intercept a STAR and vertical navi-
gation clearance.
“Proceed dir ect Leoni, descend via the Leoni One ar-
rival.”
“Proceed direct Denis, cross Denis at or above flight
level two zero zero, then descend via the Mmell One ar-
rival.”
NOTE−
In Example 5, in the first clearance an altitude is published
at Leoni; the aircraft proceeds to Leoni, crosses Leoni at
the published altitude and then descends via the arrival. Ifa speed restrictions is published at Leoni, the aircraft willslow to comply with the published speed.
In the second clearance, there is no altitude published atDenis; the aircraft must cross Denis at or above FL200,
and then descends via the arrival.
(b)Pilots cleared for vertical navigation
using the phraseology “descend via” must inform
ATC upon initial contact with a new frequency, of thealtitude leaving, “descending via (procedure name),”
the runway transition or landing direction if assigned,
and any assigned restrictions not published on theprocedure.
EXAMPLE −
1.Delta 121 is cleared to descend via the Eagul Five ar-
rival, runway 26 transition: “Delta One Twenty One
leaving flight level one niner zero, descending via theEagul Five arrival runway two-six transition.”
2.Delta 121 is cleared to descend via the Eagul Five ar-
rival, but ATC has changed the bottom altitude to 12,000:
“Delta One Twenty One leaving flight level one niner zero
for one two thousand, descending via the Eagul Five ar-
rival, runway two-six transition.”
3.(JetBlue 602 is cleared to descend via the Ivane Two ar-
rival, landing south): “JetBlue six zero two leaving flight
level two one zero descending via the Ivane Two arrival
landing south.”
b.Pilots of IFR aircraft destined to locations for
which STARs have been published may be issued a
clearance containing a STAR whenever ATC deems
it appropriate.
c.Use of STARs requires pilot possession of at
least the approved chart. RNA V STARs must be
retrievable by the procedure name from the aircraftdatabase and conform to charted procedure. As with
any ATC clearance or portion thereof, it is the
responsibility of each pilo t to accept or refuse an
issued STAR. Pilots should notify ATC if they do not
wish to use a STAR by placing “NO STAR” in the
remarks section of the flight plan or by the lessdesirable method of verbally stating the same to ATC.
d.STAR charts are published in the Terminal
Procedures Publications (TPP) and are available onsubscription from the National Aeronautical
Charting Office.
e. RNA V STAR.
1.All public RNA V STARs are RNA V1. These
procedures require system performance currently
met by GPS or DME/DME/IRU RNA V systems that
satisfy the criteria discussed in AC 90 −100A, U.S.
AIM 10/12/17
5−4−3 Arrival ProceduresTerminal and En Route Area Navigation (RNA V)
Operations. RNA V1 procedures must maintain a total
system error of not more than 1 NM for 95% of the
total flight time.
2.For procedures requiring GPS, if the
navigation system does not automatically alert theflight crew of a loss of GPS, the operator must
develop procedures to verify correct GPS operation.
REFERENCE −
AIM, Global Positioning System (GPS)
Paragraph 1 −1−17 k, Impact of Magnetic Variation on PBN Systems
5−4−2. Local Flow Traffic Management Pro-
gram
a.This program is a continuing effort by the FAA
to enhance safety, minimize the impact of aircraft
noise and conserve aviation fuel. The enhancement of
safety and reduction of noise is achieved in thisprogram by minimizing low altitude maneuvering of
arriving turbojet and turboprop aircraft weighing
more than 12,500 pounds and, by permittingdeparture aircraft to climb to higher altitudes sooner,
as arrivals are operating at higher altitudes at the
points where their flight paths cross. The application
of these procedures also reduces exposure time
between controlled aircraft and uncontrolled aircraftat the lower altitudes in and around the terminal
environment. Fuel conservation is accomplished by
absorbing any necessary arrival delays for aircraftincluded in this program operating at the higher and
more fuel efficient altitudes.
b.A fuel efficient descent is basically an
uninterrupted descent (except where level flight isrequired for speed adjustment) from cruising altitude
to the point when level flight is necessary for the pilot
to stabilize the aircraft on final approach. Theprocedure for a fuel efficient descent is based on an
altitude loss which is most efficient for the majority
of aircraft being served. This will generally result ina descent gradient window of 250 −350 feet per
nautical mile.
c.When crossing altitudes and speed restrictions
are issued verbally or are depicted on a chart, ATCwill expect the pilot to descend first to the crossing
altitude and then reduce speed. Verbal clearances for
descent will normally permit an uninterrupteddescent in accordance with the procedure as
described in paragraph b above. Acceptance of a
charted fuel efficient descent (Runway ProfileDescent) clearance requires the pilot to adhere to the
altitudes, speeds, and headings depicted on the charts
unless otherwise instructed by ATC. PILOTS
RECEIVING A CLEARANCE FOR A FUEL
EFFICIENT DESCENT ARE EXPECTED TOADVISE A TC IF THEY DO NOT HA VE RUNWAY
PROFILE DESCENT CHARTS PUBLISHED FOR
THAT AIRPORT OR ARE UNABLE TO COMPLYWITH THE CLEARANCE.
5−4−3. Approach Control
a.Approach control is responsible for controlling
all instrument flight operating within its area of
responsibility. Approach control may serve one or
more airfields, and control is exercised primarily bydirect pilot and controller communications. Prior to
arriving at the destination radio facility, instructions
will be received from ARTCC to contact approach
control on a specified frequency.
b. Radar Approach Control.
1.Where radar is approved for approach control
service, it is used not only for radar approaches
(Airport Surveillance Radar [ASR] and Precision
Approach Radar [PAR]) but is also used to providevectors in conjunction with published nonradar
approaches based on radio NA V AIDs (ILS, VOR,
NDB, TACAN). Radar vectors can provide courseguidance and expedite traffic to the final approach
course of any established IAP or to the traffic pattern
for a visual approach. Approach control facilities thatprovide this radar service will operate in the
following manner:
(a)Arriving aircraft are either cleared to an
outer fix most appropriate to the route being flown
with vertical separation and, if required, givenholding information or, when radar handoffs are
effected between the ARTCC and approach control,
or between two approach control facilities, aircraftare cleared to the airport or to a fix so located that the
handoff will be completed prior to the time the
aircraft reaches the fix. When radar handoffs areutilized, successive arriving flights may be handed
off to approach control with radar separation in lieu
of vertical separation.
(b)After release to approach control, aircraft
are vectored to the final approach course (ILS, RNA V,GLS, VOR, ADF, etc.). Radar vectors and altitude or
flight levels will be issued as required for spacing and
separating aircraft. Therefore, pilots must not deviate
AIM 10/12/17
5−4−4 Arrival Proceduresfrom the headings issued by approach control.
Aircraft will normally be informed when it is
necessary to vector across the final approach course
for spacing or other reasons. If approach course
crossing is imminent and the pilot has not beeninformed that the aircraft will be vectored across the
final approach course, the pilot should query the
controller.
(c)The pilot is not expected to turn inbound
on the final approach course unless an approachclearance has been issued. This clearance will
normally be issued with the final vector for
interception of the final approach course, and thevector will be such as to enable the pilot to establish
the aircraft on the final approach course prior to
reaching the final approach fix.
(d)In the case of aircraft already inbound on
the final approach course, approach clearance will be
issued prior to the aircraft reaching the final approach
fix. When established inbound on the final approach
course, radar separation will be maintained and thepilot will be expected to complete the approach
utilizing the approach aid designated in the clearance
(ILS, RNA V , GLS, VOR, radio beacons, etc.) as the
primary means of navigation. Therefore, once estab-
lished on the final approach course, pilots must notdeviate from it unless a clearance to do so is received
from ATC.
(e)After passing the final approach fix on
final approach, aircraft are expected to continue
inbound on the final approach course and completethe approach or ef fect the missed approach procedure
published for that airport.
2.ARTCCs are approved for and may provide
approach control services to specific airports. The
radar systems used by these centers do not provide the
same precision as an ASR/PAR used by approach
control facilities and towers, and the update rate is not
as fast. Therefore, pilots may be requested to reportestablished on the final approach course.
3.Whether aircraft are vectored to the appropri-
ate final approach course or provide their own
navigation on published routes to it, radar service is
automatically terminated when the landing iscompleted or when instructed to change to advisory
frequency at uncontrolled airports, whichever occurs
first.5−4−4. Advance Information on Instrument
Approach
a.When landing at airports with approach control
services and where two or more IAPs are published,
pilots will be provided in advance of their arrival with
the type of approach to expect or that they may be
vectored for a visual approach. This information will
be broadcast either by a controller or on ATIS. It will
not be furnished when the visibility is three miles or
better and the ceiling is at or above the highest initial
approach altitude established for any low altitude IAP
for the airport.
b.The purpose of this information is to aid the
pilot in planning arrival actions; however, it is not an
ATC clearance or commitment and is subject to
change. Pilots should bear in mind that fluctuating
weather, shifting winds, blocked runway, etc., are
conditions which may result in changes to approach
information previously received. It is important thatpilots advise ATC immediately they are unable to
execute the approach ATC advised will be used, or if
they prefer another type of approach.
c.Aircraft destined to uncontrolled airports,
which have automated weather data with broadcast
capability, should monitor the ASOS/AWSS/AWOSfrequency to ascertain the current weather for the
airport. The pilot must advise ATC when he/she has
received the broadcast weather and state his/her
intentions.
NOTE−
1.ASOS/AWSS/AWOS should be set to provide one −
minute br oadcast weather updates at uncontr olled airports
that are without weather broadcast capability by a human
observer .
2.Controllers will consider the long line disseminated
weather from an automated weather system at an
uncontrolled airport as trend and planning information
only and will rely on the pilot for current weatherinformation for the airport. If the pilot is unable to receive
the current broadcast weather, the last long line
disseminated weather will be issued to the pilot. Whenreceiving IFR services, the pilot/aircraft operator isresponsible for determining if weather/visibility is
adequate for approach/landing.
d.When making an IFR approach to an airport not
served by a tower or FSS, after ATC advises
“CHANGE TO ADVISORY FREQUENCY AP-PROVED” you should broadcast your intentions,
including the type of approach being executed, your
position, and when over the final approach fix
AIM 10/12/17
5−4−5 Arrival Proceduresinbound (nonprecision approach) or when over the
outer marker or fix used in lieu of the outer marker
inbound (precision approach). Continue to monitor
the appropriate frequency (UNICOM, etc.) for
reports from other pilots.
5−4−5. Instrument Approach Procedure
(IAP) Charts
a.14 CFR Section 91.175(a), Instrument ap-
proaches to civil airports, requires the use of SIAPs
prescribed for the airport in 14 CFR Part 97 unless
otherwise authorized by the Administrator (including
ATC). If there are military procedures published at a
civil airport, aircraft operating under 14 CFR Part 91
must use the civil procedure(s). Civil procedures aredefined with “F AA” in parenthesis; e.g., (FAA), at the
top, center of the procedure chart. DOD procedures
are defined using the abbreviation of the applicablemilitary service in parenthesis; e.g., (USAF), (USN),
(USA). 14 CFR Section 91.175(g), Military airports,
requires civil pilots flying into or out of militaryairports to comply with the IAPs and takeoff and
landing minimums prescribed by the authority
having jurisdiction at those airports. Unless an
emergency exists, civil aircraft operating at military
airports normally require advance authorization,commonly referred to as “Prior Permission
Required” or “PPR.” Information on obtaining a PPR
for a particular military airport can be found in theChart Supplement U.S.
NOTE−
Civil air craft may conduct practice VFR approaches using
DOD instrument approach procedures when approved by
the air traffic controller.
1.IAPs (standard and special, civil and military)
are based on joint civil and military criteria contained
in the U.S. Standard for TERPS. The design of IAPs
based on criteria contained in TERPS, takes into
account the interrelationship between airports,facilities, and the surrounding environment, terrain,
obstacles, noise sensitivity, etc. Appropriate
altitudes, courses, headings, distances, and otherlimitations are specified and, once approved, the
procedures are published and distributed by
government and commercial cartographers asinstrument approach charts.
2.Not all IAPs are published in chart form.
Radar IAPs are established where requirements and
facilities exist but they are printed in tabular form inappropriate U.S. Government Flight Information
Publications.
3.The navigation equipment required to join
and fly an instrument approach procedure is indicatedby the title of the procedure and notes on the chart.
(a)Straight−in IAPs are identified by the
navigational system providing the final approach
guidance and the runway to which the approach is
aligned (e.g., VOR RWY 13). Circling onlyapproaches are identified by the navigational system
providing final approach guidance and a letter
(e.g., VOR A). More than one navigational systemseparated by a slash indicates that more than one type
of equipment must be used to execute the final
approach (e.g., VOR/DME RWY 31). More than one
navigational system separated by the word “or” indi-
cates either type of equipment may be used to execute
the final approach (e.g., VOR or GPS RWY 15).
(b)In some cases, other types of navigation
systems including radar may be required to execute
other portions of the approach or to navigate to the
IAF (e.g., an NDB procedure turn to an ILS, an NDBin the missed approach, or radar required to join the
procedure or identify a fix). When radar or other
equipment is required for procedure entry from theen route environment, a note will be charted in the
planview of the approach procedure chart
(e.g., RADAR REQUIRED or ADF REQUIRED).When radar or other equipment is required on
portions of the procedure outside the final approach
segment, including the missed approach, a note willbe charted in the notes box of the pilot briefing
portion of the approach chart (e.g., RADAR
REQUIRED or DME REQUIRED). Notes are notcharted when VOR is required outside the final
approach segment. Pilots should ensure that the
aircraft is equipped with the required NA V AID(s) inorder to execute the approach, including the missed
approach.
NOTE−
Some military (i.e., U.S. Air Force and U.S. Navy)
IAPs have these “additional equipment required”
notes charted only in the planview of the approach
procedure and do not conform to the same application
standards used by the FAA.
(c)The FAA has initiated a program to
provide a new notation for LOC approaches when
charted on an ILS approach requiring other
navigational aids to fly the final approach course. The
AIM 10/12/17
5−4−6 Arrival ProceduresLOC minimums will be annotated with the NA VAID
required (e.g., “DME Required” or “RADAR
Required”). During the transition period, ILS
approaches will still exist without the annotation.
(d)Many ILS approaches having minima
based on RVR are eligible for a landing minimum ofRVR 1800. Some of these approaches are to runways
that have touchdown zone and centerline lights. For
many runways that do not have touchdown andcenterline lights, it is still possible to allow a landing
minimum of RVR 1800. For these runways, the
normal ILS minimum of RVR 2400 can be annotated
with a single or double asterisk or the dagger symbol
“
†”; for example “** 696/24 200 (200/1/2).” A note
is included on the chart stating “**RVR 1800authorized with use of FD or AP or HUD to DA.” The
pilot must use the flight director, or autopilot with an
approved approach coupler, or head up display to
decision altitude or to the initiation of a missed
approach. In the interest of safety, single pilotoperators should not fly approaches to 1800 RVR
minimums on runways without touchdown and
centerline lights using only a flight director, unlessaccompanied by the use of an autopilot with an
approach coupler.
(e)The naming of multiple approaches of the
same type to the same runway is also changing.Multiple approaches with the same guidance will be
annotated with an alphabetical suffix beginning at the
end of the alphabet and working backwards forsubsequent procedures (e.g., ILS Z RWY 28, ILS Y
RWY 28, etc.). The existing annotations such as
ILS 2 RWY 28 or Silver ILS RWY 28 will be phased
out and replaced with the new designation. The Cat II
and Cat III designations are used to differentiatebetween multiple ILSs to the same runway unless
there are multiples of the same type.
(f)RNA V (GPS) approaches to LNA V , LP,
LNA V/VNA V and LPV lines of minima using WAAS
and RNA V (GPS) approaches to LNA V and
LNA V/VNA V lines of minima using GPS are charted
as RNA V (GPS) R WY (Number) (e.g., RNA V (GPS)
RWY 21). VOR/DME RNA V approaches will
continue to be identified as VOR/DME RNA V RWY
(Number) (e.g., VOR/DME RNA V RWY 21).VOR/DME RNA V procedures which can be flown by
GPS will be annotated with “or GPS”
(e.g., VOR/DME RNA V or GPS RWY 31).4.Approach minimums are based on the local
altimeter setting for that airport, unless annotated
otherwise; e.g., Oklahoma City/Will Rogers World
approaches are based on having a Will Rogers W orld
altimeter setting. When a dif ferent altimeter source is
required, or more than one source is authorized, it will
be annotated on the approach chart; e.g., use Sidney
altimeter setting, if not received, use Scottsbluffaltimeter setting. Approach minimums may be raised
when a nonlocal altimeter source is authorized. When
more than one altimeter source is authorized, and the
minima are different, they will be shown by separate
lines in the approach minima box or a note; e.g., use
Manhattan altimeter setting; when not available useSalina altimeter setting and increase all MDAs
40 feet. When the altimeter must be obtained from a
source other than air traffic a note will indicate thesource; e.g., Obtain local altimeter setting on CTAF.
When the altimeter setting(s) on which the approach
is based is not available, the approach is notauthorized. Baro −VNA V must be flown using the
local altimeter setting only. Where no local altimeter
is available, the LNA V/VNA V line will still bepublished for use by W AAS receivers with a note that
Baro−VNA V is not authorized. When a local and at
least one other altimeter setting source is authorized
and the local altimeter is not available Baro −VNA V
is not authorized; however, the LNA V/VNA Vminima can still be used by W AAS receivers using the
alternate altimeter setting source.
NOTE−
Barometric Vertical Navigation (baro −VNAV). An RNAV
system function which uses barometric altitude informa-
tion from the aircraft’ s altimeter to compute and present
a vertical guidance path to the pilot. The specified vertical
path is computed as a geometric path, typically computedbetween two waypoints or an angle based computationfrom a single waypoint. Further guidance may be found in
Advisory Cir cular 90−105.
5.A pilot adhering to the altitudes, flight paths,
and weather minimums depicted on the IAP chart or
vectors and altitudes issued by the radar controller, is
assured of terrain and obstruction clearance andrunway or airport alignment during approach for
landing.
6.IAPs are designed to provide an IFR descent
from the en route environment to a point where a safe
landing can be made. They are prescribed andapproved by appropriate civil or military authority to
ensure a safe descent during instrument flight
conditions at a specific airport. It is important that
AIM 10/12/17
5−4−7 Arrival Procedurespilots understand these procedures and their use prior
to attempting to fly instrument approaches.
7.TERPS criteria are provided for the following
types of instrument approach procedures:
(a)Precision Approach (PA). An instrument
approach based on a navigation system that provides
course and glidepath deviation information meetingthe precision standards of ICAO Annex 10. For
example, PAR, ILS, and GLS are precision
approaches.
(b)Approach with V ertical Guidance (APV).
An instrument approach based on a navigationsystem that is not required to meet the precision
approach standards of ICAO Annex 10 but provides
course and glidepath deviation information. Forexample, Baro −VNA V , LDA with glidepath,
LNA V/VNA V and LPV are APV approaches.
(c)Nonprecision Approach (NPA). An in-
strument approach based on a navigation system
which provides course deviation information, but noglidepath deviation information. For example, VOR,
NDB and LNA V. As noted in subparagraph k, V ertical
Descent Angle (VDA) on Nonprecision Approaches,
some approach procedures may provide a Vertical
Descent Angle as an aid in flying a stabilized
approach, without requiring its use in order to fly the
procedure. This does not make the approach an APV
procedure, since it must still be flown to an MDA and
has not been evaluated with a glidepath.
b.The method used to depict prescribed altitudes
on instrument approach charts differs according totechniques employed by different chart publishers.
Prescribed altitudes may be depicted in four dif ferent
configurations: minimum, maximum, mandatory,and recommended. The U.S. Government distributes
charts produced by National Geospatial −Intelligence
Agency (NGA) and FAA. Altitudes are depicted onthese charts in the profile view with underscore,
overscore, both or none to identify them as minimum,
maximum, mandatory or recommended.
1.Minimum altitude will be depicted with the
altitude value underscored. Aircraft are required tomaintain altitude at or above the depicted value,
e.g., 3000
.2.Maximum altitude will be depicted with the
altitude value overscored. Aircraft are required to
maintain altitude at or below the depicted value,
e.g., 4000 .
3.Mandatory altitude will be depicted with the
altitude value both underscored and overscored.
Aircraft are required to maintain altitude at the
depicted value, e.g., 5000 .
4.Recommended altitude will be depicted with
no overscore or underscore. These altitudes are
depicted for descent planning, e.g., 6000.
NOTE−
1.Pilots are cautioned to adhere to altitudes as pr escribed
because, in certain instances, they may be used as the basis
for vertical separation of aircraft by ATC. When a depicted
altitude is specified in the ATC clearance, that altitude be-
comes mandatory as defined above.
2.The ILS glide slope is intended to be intercepted at the
published glide slope intercept altitude. This point marks
the PF AF and is depicted by the ”lightning bolt” symbolon U.S. Government charts. Intercepting the glide slope
at this altitude marks the beginning of the final
approach segment and ensures required obstacle clear-ance during descent from the glide slope intercept altitude
to the lowest published decision altitude for the approach.
Interception and tracking of the glide slope prior to thepublished glide slope interception altitude does not
necessarily ensure that minimum, maximum, and/or
mandatory altitudes published for any preceding fixeswill be complied with during the descent. If the pilot
chooses to track the glide slope prior to the glide slope
interception altitude, they remain responsible for comply-ing with published altitudes for any preceding stepdownfixes encountered during the subsequent descent.
3.Approaches used for simultaneous (parallel) independ-
ent and simultaneous close parallel operationsprocedurally require descending on the glideslope from the
altitude at which the approach clearance is issued (refer to
5-4-15 and 5-4-16). For simultaneous close parallel
(PRM) approaches, the Attention All Users Page (AAUP)may publish a note which indicates that descending on the
glideslope/glidepath meets all crossing restrictions.
However , if no such note is published, and for simultaneous
independent approaches (4300 and greater runway
separation) where an AAUP is not published, pilots are
cautioned to monitor their descent on the glideslope/pathoutside of the PF AF to ensure compliance with published
crossing restrictions during simultaneous operations.
AIM 10/12/17
5−4−8 Arrival Procedures4.When parallel approach courses are less than 2500 feet
apart and reduced in-trail spacing is authorized forsimultaneous dependent operations, a chart note will
indicate that simultaneous operations require use of
vertical guidance and that the pilot should maintain lastassigned altitude until established on glide slope. These
approaches procedurally require utilization of the ILS
glide slope for wake turbulence mitigation. Pilots shouldnot confuse these simultaneous dependent operations with
(SOIA) simultaneous close parallel PRM approaches,
where PRM appears in the approach title.
5.Altitude restrictions depicted at stepdown
fixes within the final approach segment are
applicable only when flying a Non −PrecisionApproach to a straight −in or circling line of minima
identified as a MDA(H). Stepdown fix altitude
restrictions within the final approach segment do not
apply to pilots using Precision Approach (ILS) or
Approach with Vertical Guidance (LPV , LNA V/
VNAV) lines of minima identified as a DA(H), since
obstacle clearance on these approaches are based on
the aircraft following the applicable vertical
guidance. Pilots are responsible for adherence to
stepdown fix altitude restrictions when outside the
final approach segment (i.e., initial or intermediate
segment), regardless of which type of procedure the
pilot is flying. (See FIG 5−4−1.)
FIG 5−4−1
Instrument Approach Procedure Stepdown Fixes
AIM 10/12/17
5−4−9 Arrival Proceduresc. Minimum Safe Altitudes (MSA) are published
for emergency use on IAP charts. MSAs provide
1,000 feet of clearance over all obstacles, but do not
necessarily assure acceptable navigation signal
coverage. The MSA depiction on the plan view of an
approach chart contains the identifier of the center
point of the MSA, the applicable radius of the MSA,
a depiction of the sector(s), and the minimumaltitudes above mean sea level which provide
obstacle clearance. For conventional navigation
systems, the MSA is normally based on the primaryomnidirectional facility on which the IAP is
predicated, but may be based on the airport reference
point (ARP) if no suitable facility is available. ForRNA V approaches, the MSA is based on an RNA V
waypoint. MSAs normally have a 25 NM radius;
however, for conventional navigation systems, thisradius may be expanded to 30 NM if necessary to
encompass the airport landing surfaces. A single
sector altitude is normally established, however when
the MSA is based on a facility and it is necessary to
obtain relief from obstacles, an MSA with up to four
sectors may be established.
d. Terminal Arrival Area (TAA)
1.The TAA provides a transition from the en
route structure to the terminal environment with little
required pilot/air traffic control interface for aircraft
equipped with Area Navigation (RNA V) systems. ATAA provides minimum altitudes with standard
obstacle clearance when operating within the TAA
boundaries. TAAs are primarily used on RNA V
approaches but may be used on an ILS approach when
RNA V is the sole means for navigation to the IF;however, they are not normally used in areas of heavy
concentration of air traffic.
2.The basic design of the RNA V procedure
underlying the TAA is normally the “T” design (also
called the “Basic T”). The “T” design incorporates
two IAFs plus a dual purpose IF/IAF that functions as
both an intermediate fix and an initial approach fix.The T configuration continues from the IF/IAF to the
final approach fix (FAF) and then to the missed
approach point (MAP). The two base leg IAFs aretypically aligned in a straight-line perpendicular to
the intermediate course connecting at the IF/IAF. A
Hold-in-Lieu-of Procedure Turn (HILPT) isanchored at the IF/IAF and depicted on U.S.
Government publications using the “hold −in−lieu
−of−PT” holding pattern symbol. When the HILPT is
necessary for course alignment and/or descent, the
dual purpose IF/IAF serves as an IAF during the entry
into the pattern. Following entry into the HILPTpattern and when flying a route or sector labeled
“NoPT,” the dual-purpose fix serves as an IF , marking
the beginning of the Intermediate Segment. SeeFIG 5−4−2 and FIG 5−4−3 for the Basic “T” TAA
configuration.
AIM 10/12/17
5−4−10 Arrival ProceduresFIG 5−4−2
Basic “T” Design
FIG 5−4−3
Basic “T” Design
AIM 10/12/17
5−4−11 Arrival Procedures3.The standard TAA based on the “T” design
consists of three areas defined by the Initial Approach
Fix (IAF) legs and the intermediate segment course
beginning at the IF/IAF. These areas are called the
straight−in, left−base, and right −base areas. (See
FIG 5−4−4). TAA area lateral boundaries are
identified by magnetic courses TO the IF/IAF. The
straight−in area can be further divided intopie−shaped sectors with the boundaries identified by
magnetic courses TO the (IF/ IAF), and may contain
stepdown sections defined by arcs based on RNA V
distances from the IF/IAF. (See FIG 5 −4−5). The
right/left−base areas can only be subdivided using
arcs based on RNA V distances from the IAFs for
those areas.
FIG 5−4−4
TAA Area
4.Entry from the terminal area onto the
procedure is normally accomplished via a no
procedure turn (NoPT) routing or via a course
reversal maneuver. The published procedure will be
annotated “NoPT” to indicate when the coursereversal is not authorized when flying within a
particular TAA sector. Otherwise, the pilot is
expected to execute the course reversal under theprovisions of 14 CFR Section 91.175. The pilot may
elect to use the course reversal pattern when it is not
required by the procedure, but must receive clearance
from air traffic control before beginning the
procedure.
(a)ATC should not clear an aircraft to the left
base leg or right base leg IAF within a TAA at an inter-
cept angle exceeding 90 degrees. Pilots must not
execute the HILPT course reversal when the sector or
procedure segment is labeled “NoPT.”(b)ATC may clear aircraft direct to the fix
labeled IF/IAF if the course to the IF/IAF is within the
straight-in sector labeled “NoPT” and the intercept
angle does not exceed 90 degrees. Pilots are expected
to proceed direct to the IF/IAF and accomplish a
straight-in approach. Do not execute HILPT course
reversal. Pilots are also expected to fly the straight −in
approach when ATC provides radar vectors and mon-
itoring to the IF/IAF and issues a “straight-in”
approach clearance; otherwise, the pilot is expected
to
execute the HILPT course reversal.
REFERENCE −
AIM, Paragraph 5 −4−6 , Approach Clearance
(c)On rare occasions, ATC may clear the air-
craft for an approach at the airport without specifying
the approach procedure by name or by a specific ap-
proach (for example, “cleared RNA V Runway 34
approach”) without specifying a particular IAF. Ineither case, the pilot should proceed direct to the IAF
AIM 10/12/17
5−4−12 Arrival Proceduresor to the IF/IAF associated with the sector that the
aircraft will enter the TAA and join the approach
course from that point and if required by that sector
(i.e., sector is not labeled “NoPT), complete the
HILPT course reversal.
NOTE−
If approaching with a TO bearing that is on a sector bound-ary, the pilot is expected to proceed in accordance with a“NoPT” routing unless otherwise instructed by ATC.
5.Altitudes published within the TAA replace
the MSA altitude. However, unlike MSA altitudes the
TAA altitudes are operationally usable altitudes.These altitudes provide at least 1,000 feet of obstacle
clearance, more in mountainous areas. It is important
that the pilot knows which area of the TAA the aircraft
will enter in order to comply with the minimum
altitude requirements. The pilot can determine which
area of the TAA the aircraft will enter by determining
the magnetic bearing of the aircraft TO the fix labeled
IF/IAF. The bearing should then be compared to the
published lateral boundary bearings that define theTAA areas. Do not use magnetic bearing to the
right-base or left-base IAFs to determine position.
(a)An ATC clearance direct to an IAF or to
the IF/IAF without
an approach clearance does notauthorize a pilot to descend to a lower TAA altitude.
If a pilot desires a lower altitude without an approach
clearance, request the lower TAA altitude from ATC.
Pilots not sure of the clearance should confirm their
clearance with ATC or request a specific clearance.Pilots entering the TAA with two −way radio commu-
nications failure (14 CFR Section 91.185, IFR
Operations: Two −way Radio Communications Fail-
ure), must maintain the highest altitude prescribed by
Section 91.185(c)(2) until arriving at the appropriate
IAF.
(b)Once cleared for the approach, pilots may
descend in the TAA sector to the minimum altitudedepicted within the defined area/subdivision, unless
instructed otherwise by air traffic control. Pilots
should plan their descent within the TAA to permit a
normal descent from the IF/IAF to the FAF. In
FIG 5−4−5, pilots within the left or right −base areas
are expected to maintain a minimum altitude of 6,000feet until within 17 NM of the associated IAF. After
crossing the 17 NM arc, descent is authorized to the
lower charted altitudes. Pilots approaching from thenorthwest are expected to maintain a minimum alti-
tude of 6,000 feet, and when within 22 NM of the
IF/IAF, descend to a minimum altitude of 2,000 feet
MSL until crossing the IF/IAF.
FIG 5−4−5
Sectored TAA Areas
6.U.S. Government charts depict TAAs using
icons located in the plan view outside the depiction ofthe actual approach procedure. (See FIG 5 −4−6). Use
AIM 10/12/17
5−4−13 Arrival Proceduresof icons is necessary to avoid obscuring any portion
of the “T” procedure (altitudes, courses, minimum
altitudes, etc.). The icon for each TAA area will be
located and oriented on the plan view with respect to
the direction of arrival to the approach procedure, and
will show all TAA minimum altitudes andsector/radius subdivisions. The IAF for each area of
the TAA is included on the icon where it appears on
the approach to help the pilot orient the icon to the
approach procedure. The IAF name and the distance
of the TAA area boundary from the IAF are included
on the outside arc of the TAA area icon.
FIG 5−4−6
RNA V (GPS) Approach Chart
7.TAAs may be modified from the standard size
and shape to accommodate operational or ATCrequirements. Some areas may be eliminated, while
the other areas are expanded. The “T” design may be
AIM 10/12/17
5−4−14 Arrival Proceduresmodified by the procedure designers where required
by terrain or ATC considerations. For instance, the
“T” design may appear more like a regularly or
irregularly shaped “Y ,” upside down “L,” or an “I.”
(a)FIG 5-4-6 depicts a TAA without a left
base leg and right base leg. In this generalized ex-ample, pilots approaching on a bearing TO the IF/IAF
from 271 clockwise to 089 are expected to execute a
course reversal because the amount of turn required
at the IF/IAF exceeds 90 degrees. The term “NoPT”
will be annotated on the boundary of the TAA icon for
the other portion of the TAA.
FIG 5−4−7
TAA with Left and Right Base Areas Eliminated
(b)FIG 5−4−8 depicts another TAA modific-
ation that pilots may encounter. In this generalized
example, the left base area and part of the straight-in
area have been eliminated. Pilots operating within the
TAA between 210 clockwise to 360 bearing TO theIF/IAF are expected to proceed direct to the IF/IAF
and then execute the course reversal in order to prop-
erly align the aircraft for entry onto the intermediatesegment or to avoid an excessive descent rate. Air-
craft operating in areas from 001 clockwise to 090bearing TO t he IF/IAF are expected to proceed direct
to the right base IAF and not execute course reversal
maneuver. Aircraft cleared direct the IF/IAF by ATC
in this sector will be expected to accomplish HILTP.
Aircraft oper ating in areas 091 clockwise to 209 bear-
ing TO the IF/IAF are expected to proceed direct to
the IF/IAF and not execute the course reversal. These
two areas are annotated “NoPT” at the T AA boundary
of the icon in these areas when displayed on the ap-
proach chart’s plan view.
AIM 10/12/17
5−4−15 Arrival ProceduresFIG 5−4−8
TAA with Left Base and Part of Straight −In Area Eliminated
(c)FIG 5−4−9 depicts a TAA with right base leg and part of the straight-in area eliminated.
FIG 5−4−9
TAA with Right Base Eliminated
AIM 10/12/17
5−4−16 Arrival Procedures8.When an airway does not cross the lateral
TAA boundaries, a feeder route will be established
from an airway fix or NA VAID to the TAA boundary
to provide a transition from the en route structure to
the appropriate IAF. Each feeder route will terminateat the TAA boundary and will be aligned along a path
pointing to the associated IAF. Pilots should descend
to the TAA altitude after crossing the TAA boundary
and cleared for the approach by ATC.
(See FIG 5−4−10).
FIG 5−4−10
Examples of a TAA with Feeders from an Airway
9.Each waypoint on the “T” is assigned a
pronounceable 5 −letter name, except the missed
approach waypoint. These names are used for ATC
communications, RNA V databases, and aeronauticalnavigation products. The missed approach waypoint
is assigned a pronounceable name when it is not
located at the runway threshold.
AIM 10/12/17
5−4−17 Arrival ProceduresFIG 5−4−11
Minimum Vectoring Altitude Charts
160250277289N
e. Minimum Vectoring Altitudes (MV As) are
established for use by ATC when radar ATC is
exercised. MV A charts are prepared by air traffic
facilities at locations where there are numerous
different minimum IFR altitudes. Each MV A charthas sectors large enough to accommodate vectoring
of aircraft within the sector at the MV A. Each sector
boundary is at least 3 miles from the obstructiondetermining the MV A. To avoid a large sector with an
excessively high MV A due to an isolated prominent
obstruction, the obstruction may be enclosed in abuffer area whose boundaries are at least 3 miles from
the obstruction. This is done to facilitate vectoring
around the obstruction. (See FIG 5−4−11.)
1.The minimum vectoring altitude in each
sector provides 1,000 feet above the highest obstacle
in nonmountainous areas and 2,000 feet above the
highest obstacle in designated mountainous areas.Where lower MV As are required in designated
mountainous areas to achieve compatibility with
terminal routes or to permit vectoring to an IAP,1,000 feet of obstacle clearance may be authorized
with the use of Airport Surveillance Radar (ASR).
The minimum vectoring altitude will provide at least300 feet above the floor of controlled airspace.NOTE−
OROCA is an off −route altitude which provides obstruc-
tion clearance with a 1,000 foot buffer in nonmountainous
terrain areas and a 2,000 foot buffer in designated
mountainous areas within the U.S. This altitude may not
provide signal coverage from ground−based navigational
aids, air traffic control radar, or communicationscoverage.
2.Because of differences in the areas consid-
ered for MV A, and those applied to other minimum
altitudes, and the ability to isolate specific obstacles,
some MV As may be lower than the nonradar
Minimum En Route Altitudes (MEAs), MinimumObstruction Clearance Altitudes (MOCAs) or other
minimum altitudes depicted on charts for a given
location. While being radar vectored, IFR altitudeassignments by ATC will be at or above MV A.
3.The MV A/MIA may be lower than the TAA
minimum altitude. If ATC has assigned an altitude to
an aircraft that is below the TAA minimum altitude,the aircraft will either be assigned an altitude to
maintain until established on a segment of a
published route or instrument approach procedure, or
climbed to the TAA altitude.
AIM 10/12/17
5−4−18 Arrival Proceduresf. Circling. Circling minimums charted on an
RNA V (GPS) approach chart may be lower than the
LNA V/VNA V line of minima, but never lower than
the LNA V line of minima (straight-in approach).
Pilots may safely perform the circling maneuver atthe circling published line of minima if the approach
and circling maneuver is properly performed
according to aircraft category and operational
limitations.
FIG 5−4−12
Example of LNA V and Circling Minima Lower Than LNA V/VNA V DA.
Harrisburgh International RNA V (GPS) RWY 13
CATEGORY A B C D
LPV DA 558/24 250 (300 − ½)
LNA V/
VNA V DA1572 − 5 1264 (1300 − 5)
LNA V MDA1180 / 24
872 (900 − ½)1180 / 40
872 (900 − ¾)1180 / 2
872 (900 − 2)1180 / 2 ¼
872 (900 − 2 ¼)
CIRCLING1180 − 1
870 (900 − 1)1180 − 1 ¼
870 (900 − 1 ¼)1180 − 2 ½
870 (900 − 2 ½)1180 − 2 ¾
870 (900 − 2 ¾)
FIG 5−4−13
Explanation of LNA V and/or Circling Minima Lower than LNA V/VNA V DA
g.FIG 5−4−13 provides a visual representation of
an obstacle evaluation and calculation of LNA V
MDA, Circling MDA, LNA V/VNA V DA.
1. No vertical guidance (LNA V). A line is
drawn horizontal at obstacle height and 250 feet
added for Required Obstacle Clearance (ROC). Thecontrolling obstacle used to determine LNA V MDA
can be different than the controlling obstacle used in
determining ROC for circling MDA. Other factors
may force a number larger than 250 ft to be added to
the LNA V OCS. The number is rounded up to the nexthigher 20 foot increment.
AIM 10/12/17
5−4−19 Arrival Procedures2. Circling MDA. The circling MDA will
provide 300 foot obstacle clearance within the area
considered for obstacle clearance and may be lower
than the LNA V/VNA V DA, but never lower than the
straight in LNA V MDA. This may occur whendifferent controlling obstacles are used or when other
controlling factors force the LNA V MDA to be higher
than 250 feet above the LNA V OCS. In FIG 5 −4−12,
the required obstacle clearance for both the LNA V
and Circle resulted in the same MDA, but lower than
the LNAV/VNAV DA. FIG 5 −4−13 provides an
illustration of this type of situation.
3. Vertical guidance (LNA V/VNA V). A line is
drawn horizontal at obstacle height until reaching the
obstacle clearance surface (OCS). At the OCS, avertical line is drawn until reaching the glide path.
This is the DA for the approach. This method places
the offending obstacle in front of the LNA V/VNA V
DA so it can be seen and avoided. In some situations,
this may result in the LNA V/VNA V DA being higher
than the LNA V and/or Circling MDA.
h. The Visual Descent Point (VDP) , identified by
the symbol (V), is a defined point on the final
approach course of a nonprecision straight −in
approach procedure from which a stabilized visual
descent from the MDA to the runway touchdown
point may be commenced. The pilot should notdescend below the MDA prior to reaching the VDP.
The VDP will be identified by DME or RNA V
along−track distance to the MAP. The VDP distance
is based on the lowest MDA published on the IAP and
harmonized with the angle of the visual glide slopeindicator (VGSI) (if installed) or the procedure VDA
(if no VGSI is installed). A VDP may not be
published under certain circumstances which mayresult in a destabilized descent between the MDA and
the runway touchdown point. Such circumstances
include an obstacle penetrating the visual surfacebetween the MDA and runway threshold, lack of
distance measuring capability, or the procedure
design prevents a VDP to be identified.
1.VGSI systems may be used as a visual aid to
the pilot to determine if the aircraft is in a position to
make a stabilized descent from the MDA. When the
visibility is close to minimums, the VGSI may not be
visible at the VDP due to its location beyond the
MAP.2.Pilots not equipped to receive the VDP should
fly the approach procedure as though no VDP had
been provided.
3.On a straight-in nonprecision IAP, descent
below the MDA between the VDP and the MAP may
be inadvisable or impossible. Aircraft speed, height
above the runway, descent rate, amount of turn, andrunway length are some of the factors which must be
considered by the pilot to determine if a safe descent
and landing can be accomplished.
i.A visual segment obstruction evaluation is
accomplished during procedure design on all IAPs.Obstacles (both lighted and unlighted) are allowed to
penetrate the visual segment obstacle identification
surfaces. Identified obstacle penetrations may causerestrictions to instrument approach operations which
may include an increased approach visibility
requirement, not publishing a VDP, and/or prohibit-ing night instrument operations to the runway. There
is no implicit obstacle protection from the MDA/DA
to the touchdown point. Accordingly, it is the
responsibility of the pilot to visually acquire and
avoid obstacles below the MDA/DA during transition
to landing.
1.Unlighted obstacle penetrations may result in
prohibiting night instrument operations to therunway. A chart note will be published in the pilot
briefing strip “Procedure NA at Night.”
2.Use of a VGSI may be approved in lieu of
obstruction lighting to restore night instrument
operations to the runway. A chart note will bepublished in the pilot briefing strip “ Straight-in Rwy
XX at Night, operational VGSI required, remain on
or above VGSI glidepath until threshold.”
j.The highest obstacle (man-made, terrain, or
vegetation) will be charted on the planview of an IAP.
Other obstacles may be charted in either the planview
or the airport sketch based on distance from the
runway and available chart space. The elevation ofthe charted obstacle will be shown to the nearest foot
above mean sea level. Obstacles without a verified
accuracy are indicated by a ± symbol following the
elevation value.
k. Vertical Descent Angle (VDA). FAA policy is
to publish VDAs on all nonprecision approaches
except those published in conjunction with vertically
guided minimums or no-FAF procedures without
step-down fixes. A VDA does not guarantee obstacle
protection below the MDA in the visual segment. The
AIM 10/12/17
5−4−20 Arrival Procedurespresence of a VDA does not change any nonprecision
approach requirements.
1.Obstacles may penetrate the visual segment
of an IAP that has a published VDA. When the VDA
is not authorized due to an obstacle penetration that
would require a pilot to deviate from the VDAbetween MDA and touchdown, the VDA/TCH will
be replaced with the note “Visual Segment-
Obstacles” in the profile view of the IAP (SeeFIG 5−4−14). Accordingly, pilots are advised to
carefully review approach procedures to identify
where the optimum stabilized descent to landing canbe initiated. Pilots that follow the previously
published descent angle below the MDA on
procedures with this note may encounter obstacles in
the visual segment.2.The threshold crossing height (TCH) used to
compute the descent angle is published with the
VDA. The VDA and TCH information are charted on
the profile view of the IAP following the fix
(FAF/stepdown) used to compute the VDA. If noPA/APV IAP is established to the same runway, the
VDA will be equal to or higher than the glide path
angle of the VGSI installed on the same runwayprovided it is within instrument procedure criteria. A
chart note will indicate if the VGSI is not coincident
with the VDA. Pilots must be aware that thepublished VDA is for advisory information only and
not to be considered instrument procedure derived
vertical guidance. The VDA solely offers an aid tohelp pilots establish a continuous, stabilized descent
during final approach.
FIG 5−4−14
Example of a Chart Note
3.Pilots may use the published angle and
estimated/actual groundspeed to find a target rate of
descent from the rate of descent table published in the
back of the U.S. Terminal Procedures Publication.
This rate of descent can be flown with the VerticalVelocity Indicator (VVI) in order to use the VDA as
an aid to flying a stabilized descent. No special
equipment is required.
4.A straight −in aligned procedure may be
restricted to circling only minimums when anexcessive descent gradient necessitates. The descent
angle between the F AF/stepdown fix and the Circling
MDA must not exceed the maximum descent angleallowed by TERPS criteria. A published VDA onthese procedures does not imply that landing straight
ahead is recommended or even possible. The descent
rate based on the VDA may exceed the capabilities of
the aircraft and the pilot must determine how to best
maneuver the aircraft within the circling area in order
to land safely.
l.In isolated cases, an IAP may contain a
published visual flight path. These procedures are
annotated “Fly Visual to Airport” or “Fly Visual.” Adashed arrow indicating the visual flight path will be
included in the profile and plan views with an
approximate heading and distance to the end of therunway.
AIM 10/12/17
5−4−21 Arrival Procedures1.The depicted ground track associated with the
“Fly Visual to Airport” segment should be flown as
a “Dead Reckoning” course. When executing the
“Fly Visual to Airport” segment, the flight visibility
must not be less than that prescribed in the IAP; thepilot must remain clear of clouds and proceed to the
airport maintaining visual contact with the ground.
Altitude on the visual flight path is at the discretionof the pilot, and it is the responsibility of the pilot to
visually acquire and avoid obstacles in the “Fly
Visual to Airport” segment.
2.Missed approach obstacle clearance is
assured only if the missed approach is commenced at
the published MAP. Before initiating an IAP that
contains a “Fly Visual to Airport” segment, the pilot
should have preplanned climb out options based onaircraft performance and terrain features. Obstacle
clearance is the responsibility of the pilot when the
approach is continued beyond the MAP.
NOTE−
The F AA Administrator retains the authority to approve
instrument approach procedures where the pilot may not
necessarily have one of the visual references specified in
14 CFR § 91.175 and related rules. It is not a function of
procedure design to ensure compliance with §91.175. The
annotation “Fly Visual to Airport” provides relief from
§91.175 requir ements that the pilot have distinctly visible
and identifiable visual references prior to descent below
MDA/DA.
m. Area Navigation (RNA V) Instrument
Approach Charts. Reliance on RNA V systems for
instrument operations is becoming more common-place as new systems such as GPS and augmented
GPS such as the Wide Area Augmentation System
(WAAS) are developed and deployed. In order tosupport full integration of RNA V procedures into the
National Airspace System (NAS), the FAA
developed a new charting format for IAPs (SeeFIG 5−4−6). This format avoids unnecessary
duplication and proliferation of instrument approach
charts. The original stand alone GPS charts, titledsimply “GPS,” are being converted to the newer
format as the procedures are revised. One reason for
the revision is the addition of WAAS based minimato the approach chart. The reformatted approach chart
is titled “RNA V (GPS) RWY XX.” Up to four lines
of minima are included on these charts. GroundBased Augmentation System (GBAS) Landing
System (GLS) was a placeholder for future WAAS
and LAAS minima, and the minima was always listedas N/A. The GLS minima line has now been replaced
by the WAAS LPV (Localizer Performance with
Vertical Guidance) minima on most RNA V (GPS)
charts. LNA V/VNA V (lateral navigation/vertical
navigation) was added to support both WAASelectronic vertical guidance and Barometric VNA V .
LPV and LNA V/VNA V are both APV procedures as
described in paragraph 5 −4−5a7. The original GPS
minima, titled “S−XX,” for straight in runway XX, is
retitled LNA V (lateral navigation). Circling minima
may also be published. A new type of nonprecisionWAAS minima will also be published on this chart
and titled LP (localizer performance). LP will be
published in locations where vertically guidedminima cannot be provided due to terrain and
obstacles and therefore, no LPV or LNA V/VNA V
minima will be published. GBAS procedures arepublished on a separate chart and the GLS minima
line is to be used only for GBAS. ATC clearance for
the RNA V procedure authorizes a properly certifiedpilot to utilize any minimums for which the aircraft is
certified (for example, a WAAS equipped aircraft
utilizes the LPV or LP minima but a GPS only aircraft
may not). The RNA V chart includes information
formatted for quick reference by the pilot or flight
crew at the top of the chart. This portion of the chart,
developed based on a study by the Department of
Transportation, V olpe National Transportation Sys-tem Center, is commonly referred to as the pilot
briefing.
1.The minima lines are:
(a) GLS. “GLS” is the acronym for GBAS
Landing System. The U.S. version of GBAS hastraditionally been referred to as LAAS. The
worldwide community has adopted GBAS as the
official term for this type of navigation system. Tocoincide with international terminology, the FAA is
also adopting the term GBAS to be consistent with the
international community. This line was originallypublished as a placeholder for both W AAS and LAAS
minima and marked as N/A since no minima was
published. As the concepts for GBAS and WAAS
procedure publication have evolved, GLS will now
be used only for GBAS minima, which will be on aseparate approach chart. Most RNA V(GPS) approach
charts have had the GLS minima line replaced by a
WAAS LPV line of minima.
(b) LPV . “LPV” is the acronym for localizer
performance with vertical guidance. RNA V (GPS)
approaches to LPV lines of minima take advantage of
AIM 10/12/17
5−4−22 Arrival Proceduresthe improved accuracy of WAAS lateral and vertical
guidance to provide an approach that is very similar
to a Category I Instrument Landing System (ILS).
The approach to LPV line of minima is designed for
angular guidance with increasing sensitivity as theaircraft gets closer to the runway . The sensitivities are
nearly identical to those of the ILS at similar
distances. This was done intentionally to allow theskills required to proficiently fly an ILS to readily
transfer to flying RNA V (GPS) approaches to the
LPV line of minima. Just as with an ILS, the LPV hasvertical guidance and is flown to a DA. Aircraft can
fly this minima line with a statement in the Aircraft
Flight Manual that the installed equipment supportsLPV approaches. This includes Class 3 and 4
TSO−C146 GPS/W AAS equipment.
(c) L N AV / V N AV. LNA V/VNA V identifies
APV minimums developed to accommodate an
RNA V IAP with vertical guidance, usually provided
by approach certified Baro −VNA V , but with lateral
and vertical integrity limits larger than a precision
approach or LPV . LNA V stands for Lateral
Navigation; VNA V stands for Vertical Navigation.This minima line can be flown by aircraft with a
statement in the Aircraft Flight Manual that the
installed equipment supports GPS approaches andhas an approach −approved barometric VNA V , or if
the aircraft has been demonstrated to support
LNA V/VNA V approaches. This includes Class 2, 3and 4 TSO −C146 GPS/WAAS equipment. Aircraft
using LNA V/VNA V minimums will descend to
landing via an internally generated descent pathbased on satellite or other approach approved VNA V
systems. Since electronic vertical guidance is
provided, the minima will be published as a DA.Other navigation systems may be specifically
authorized to use this line of minima. (See Section A,
Terms/Landing Minima Data, of the U.S. Terminal
Procedures books.)
(d) LP. “LP” is the acronym for localizer
performance. Approaches to LP lines of minima take
advantage of the improve d accuracy of WAAS to
provide approaches, with lateral guidance and
angular guidance. Angular guidance does not refer to
a glideslope angle but rather to the increased lateral
sensitivity as the aircraft gets closer to the runway,
similar to localizer approaches. However, the LP line
of minima is a Minimum Descent Altitude (MDA)
rather than a DA (H). Procedures with LP lines of
minima will not be published with another approachthat contains approved vertical guidance
(LNA V/VNA V or LPV). It is possible to have LP and
LNA V published on the same approach chart but LP
will only be published if it provides lower minima
than an LNA V line of minima. LP is not a fail −down
mode for LPV . LP will only be published if terrain,
obstructions, or some other reason prevent publishing
a vertically guided procedure. WAAS avionics mayprovide GNSS −based advisory vertical guidance
during an approach to an LP line of minima.
Barometric altimeter information remains theprimary altitude reference for complying with any
altitude restrictions. WAAS equipment may not
support LP , even if it supports LPV , if it was approved
before TSO −C145b and TSO −C146b. Receivers
approved under previous TSOs may require an
upgrade by the manufacturer in order to be used to fly
to LP minima. Receivers approved for LP must have
a statement in the approved Flight Manual or
Supplemental Flight Manual including LP as one ofthe approved approach types.
(e) LNAV. This minima is for lateral
navigation only, and the approach minimum altitudewill be published as a minimum descent altitude
(MDA). LNA V provides the same level of service as
the present GPS stand alone approaches. LNA Vminimums support the following navigation systems:
WAAS, when the navigation solution will not support
vertical navigation; and, GPS navigation systemswhich are presently authorized to conduct GPS
approaches.
NOTE−
GPS receivers approved for approach operations inaccordance with: AC 20 −138, Airworthiness Approval of
Positioning and Navigation Systems, qualify for this min-
ima. WAAS navigation equipment must be approved inaccordance with the requirements specified inTSO−C145() or TSO −C146() and installed in accordance
with Advisory Cir cular AC 20 −138.
2.Other systems may be authorized to utilize
these approaches. See the description in Section A of
the U.S. Terminal Procedures books for details.
Operational approval must also be obtained for
Baro−VNAV systems to operate to the LNA V/VNA V
minimums. Baro −VNA V may not be authorized on
some approaches due to other factors, such as no local
altimeter source being available. Baro −VNA V is not
authorized on LPV procedures. Pilots are directed to
their local Flight Standards District Office (FSDO)
for additional information.
AIM 10/12/17
5−4−23 Arrival ProceduresNOTE−
RNAV and Baro −VNAV systems must have a manufacturer
supplied electronic database which must include thewaypoints, altitudes, and vertical data for the pr ocedure to
be flown. The system must be able to retrieve the pr ocedure
by name from the aircraft navigation database, not just asa manually entered series of waypoints.
3. ILS or RNA V (GPS) charts.
(a)Some RNA V (GPS) charts will also con-
tain an ILS line of minima to make use of the ILS
precision final in conjunction with the RNA V GPScapabilities for the portions of the procedure prior to
the final approach segment and for the missed ap-
proach. Obstacle clearance for the portions of theprocedure other than the final approach segment is
still based on GPS criteria.
NOTE−
Some GPS receiver installations inhibit GPS navigationwhenever ANY ILS frequency is tuned. Pilots flying
aircraft with receivers installed in this manner must wait
until they are on the intermediate segment of the pr ocedure
prior to the PF AF (PF AF is the active waypoint) to tune theILS frequency and must tune the ILS back to a VOR fre-quency in order to fly the GPS based missed approach.
(b) Charting . There are charting dif ferences
between ILS, RNA V (GPS), and GLS approaches.
(1)The LAAS procedure is titled “GLS
RWY XX” on the approach chart.
(2)The VDB provides information to the
airborne receiver where the guidance is synthesized.
(3)The LAAS procedure is identified by a
four alpha −numeric character field referred to as the
RPI or approach ID and is similar to the IDENT fea-ture of the ILS.
(4)The RPI is charted.
(5)Most RNA V(GPS) approach charts
have had the GLS (NA) minima line replaced by an
LPV line of minima.
(6)Since the concepts for LAAS and
WAAS procedure publication have evolved, GLSwill now be used only for LAAS minima, which will
be on a separate approach chart.
4. Required Navigation Performance (RNP).
(a)Pilots are advised to refer to the
“TERMS/LANDING MINIMUMS DATA”
(Section A) of the U.S. Government TerminalProcedures books for aircraft approach eligibility
requirements by specific RNP level requirements.
(b)Some aircraft have RNP approval in their
AFM without a GPS sensor. The lowest level ofsensors that the FAA will support for RNP service is
DME/DME. However, necessary DME signal may
not be available at the airport of intended operations.
For those locations having an RNA V chart published
with LNA V/VNA V minimums, a procedure note may
be provided such as “DME/DME RNP −0.3 NA.”
This means that RNP aircraft dependent on
DME/DME to a chieve RNP −0.3 are not authorized to
conduct this approach. Where DME facility
availability is a factor, the note may read “DME/DME
RNP−0.3 Authorized; ABC and XYZ Required.”
This means that ABC and XYZ facilities have been
determined by flight inspection to be required in the
navigation solution to assure RNP −0.3. VOR/DME
updating must not be used for approach procedures.
5. Chart Terminology.
(a)Decision Altitude (DA) replaces the
familiar term Decision Height (DH). DA conforms to
the international convention where altitudes relate toMSL and heights relate to AGL. DA will eventually
be published for other types of instrument approach
procedures with vertical guidance, as well. DAindicates to the pilot that the published descent profile
is flown to the DA (MSL), where a missed approach
will be initiated if visual references for landing are not
established. Obstacle clearance is provided to allow
a momentary descent below DA while transitioning
from the final approach to the missed approach. Theaircraft is expected to follow the missed instructions
while continuing along the published final approach
course to at least the published runway thresholdwaypoint or MAP (if not at the threshold) before
executing any turns.
(b)Minimum Descent Altitude (MDA) has
been in use for many years, and will continue to beused for the LNA V only and circling procedures.
(c)Threshold Crossing Height (TCH) has
been traditionally used in “precision” approaches as
the height of the glide slope above threshold. Withpublication of LNA V/VNA V minimums and RNA V
descent angles, including graphically depicted
descent profiles, TCH also applies to the height of the
“descent angle,” or glidepath, at the threshold. Unless
otherwise required for larger type aircraft which may
be using the IAP, the typical TCH is 30 to 50 feet.
AIM 10/12/17
5−4−24 Arrival Procedures6.The MINIMA FORMAT will also change
slightly.
(a)Each line of minima on the RNA V IAP is
titled to reflect the level of service available; e.g.,
GLS, LPV , LNA V/VNA V , LP, and LNA V .
CIRCLING minima will also be provided.
(b)The minima title box indicates the nature
of the minimum altitude for the IAP. For example:
(1)DA will be published next to the
minima line title for minimums supporting vertical
guidance such as for GLS, LPV or LNA V/VNA V .
(2)MDA will be published as the minima
line on approaches with lateral guidance only, LNA V,
or LP. Descent below the MDA must meet the
conditions stated in 14 CFR Section 91.175.
(3)Where two or more systems, such as
LPV and LNA V/VNA V , share the same minima, each
line of minima will be displayed separately.
7.Chart Symbology changed slightly to
include:
(a) Descent Profile. The published descent
profile and a graphical depiction of the vertical path
to the runway will be shown. Graphical depiction ofthe RNA V vertical guidance will differ from the
traditional depiction of an ILS glide slope (feather)
through the use of a shorter vertical track beginning
at the decision altitude.
(1)It is FAA policy to design IAPs with
minimum altitudes established at fixes/waypoints toachieve optimum stabilized (constant rate) descents
within each procedure segment. This design can
enhance the safety of the operations and contributetoward reduction in the occurrence of controlled
flight into terrain (CFIT) accidents. Additionally, the
National Transportation Safety Board (NTSB)recently emphasized that pilots could benefit from
publication of the appropriate IAP descent angle for
a stabilized descent on final approach. The RNA V
IAP format includes the descent angle to the
hundredth of a degree; e.g., 3.00 degrees. The anglewill be provided in the graphically depicted descent
profile.
(2)The stabilized approach may be
performed by reference to vertical navigationinformation provided by WAAS or LNA V/VNA V
systems; or for LNA V −only systems, by the pilot
determining the appropriate aircraftattitude/groundspeed combination to attain a
constant rate descent which best emulates the
published angle. To aid the pilot, U.S. Government
Terminal Procedures Publication charts publish an
expanded Rate of Descent Table on the inside of theback hard cover for use in planning and executing
precision descents under known or approximate
groundspeed conditions.
(b) Visual Descent Point (VDP). A VDP
will be published on most RNA V IAPs. VDPs apply
only to aircraft utilizing LP or LNA V minima, notLPV or LNA V/VNA V minimums.
(c) Missed Approach Symbology. In order
to make missed approach guidance more readily
understood, a method has been developed to display
missed approach guidance in the profile view through
the use of quick reference icons. Due to limited spacein the profile area, only four or fewer icons can be
shown. However, the icons may not provide
representation of the entire missed approachprocedure. The entire set of textual missed approach
instructions are provided at the top of the approach
chart in the pilot briefing. (See FIG 5−4−6).
(d) Waypoints. All RNA V or GPS
stand−alone IAPs are flown using data pertaining to
the particular IAP obtained from an onboarddatabase, including the sequence of all WPs used for
the approach and missed approach, except that step
down waypoints may not be included in someTSO−C129 receiver databases. Included in the
database, in most receivers, is coding that informs the
navigation system of which WPs are fly −over (FO) or
fly−by (FB). The navigation system may provide
guidance appropriately − including leading the turn
prior to a fly −by WP; or causing overflight of a
fly−over WP. Where the navigation system does not
provide such guidance, the pilot must accomplish the
turn lead or waypoint overflight manually. Chartsymbology for the FB WP provides pilot awareness
of expected actions. Refer to the legend of the U.S.
Terminal Procedures books.
(e)TAAs are described in paragraph 5 −4−5d,
Terminal Arrival Area (TAA). When published, the
RNAV chart depicts the TAA areas through the use of
“icons” representing each TAA area associated with
the RNA V procedure (See FIG 5−4−6). These icons
are depicted in the plan view of the approach chart,generally arranged on the chart in accordance with
their position relative to the aircraft’s arrival from the
en route structure. The WP, to which navigation is
AIM 10/12/17
5−4−25 Arrival Proceduresappropriate and expected within each specific TAA
area, will be named and depicted on the associated
TAA icon. Each depicted named WP is the IAF for
arrivals fr om within that area. TAAs may not be used
on all RNA V procedures because of airspacecongestion or other reasons.
(f) Hot and Cold T emperature Limitations.
A minimum and maximum temperature limitationis published on procedures which authorize
Baro−VNA V operation. These temperatures
represent the airport temperature above or belowwhich Baro −VNA V is not authorized to
LNA V/VNA V minimums. As an example, the
limitation will read: “Uncompensated Baro −VNA V
NA below −8/C0095C (+18 /C0095F) or above 47 /C0095C (117 /C0095F).”
This information will be found in the upper left hand
box of the pilot briefing. When the temperature isabove the high temperature or below the low
temperature limit, Baro −VNA V may be used to
provide a stabilized descent to the LNA V MDA;however, extra caution should be used in the visual
segment to ensure a vertical correction is not
required. If the VGSI is aligned with the publishedglidepath, and the aircraft instruments indicate on
glidepath, an above or below glidepath indication on
the VGSI may indicate that temperature error is
causing deviations to the glidepath. These deviations
should be considered if the approach is continuedbelow the MDA.
NOTE−
Many systems which apply Baro −VNAV temperature
compensation only correct for cold temperature. In thiscase, the high temperature limitation still applies. Also,
temperature compensation may require activation by
maintenance personnel during installation in order to befunctional, even though the system has the feature. Somesystems may have a temperature correction capability, but
correct the Baro−altimeter all the time, rather than just on
the final, which would create conflicts with other aircraft
if the feature were activated. Pilots should be aware ofcompensation capabilities of the system prior todisregarding the temperature limitations.
NOTE−
Temperature limitations do not apply to flying the LNAV/
VNAV line of minima using approach certified WAASreceivers when LPV or LNA V/VNAV are annunciated to be
available.
(g) WAAS Channel Number/Approach ID.
The WAAS Channel Number is an optional
equipment capability that allows the use of a 5 −digit
number to select a specific final approach segmentwithout using the menu method. The Approach ID is
an airport unique 4 −character combination for
verifying the selection and extraction of the correct
final approach segment information from the aircraft
database. It is similar to the ILS ident, but displayedvisually rather than aurally. The Approach ID
consists of the letter W for WAAS, the runway
number, and a letter other than L, C or R, which could
be confused with Left, Center and Right, e.g., W35A.
Approach IDs are assigned in the order that WAAS
approaches are built to that runway number at thatairport. The WAAS Channel Number and Approach
ID are displayed in the upper left corner of the
approach procedure pilot briefing.
(h)At locations where outages of WAAS
vertical guidance may occur daily due to initial
system limitations, a negative W symbol (
) will be
placed on RNA V (GPS) approach charts. Many of
these outages will be very short in duration, but mayresult in the disruption of the vertical portion of the
approach. The
symbol indicates that NOTAMs or
Air Traffic advisories are not provided for outages
which occur in the WAAS LNA V/VNA V or LPVvertical service. Use LNA V or circling minima for
flight planning at these locations, whether as a
destination or alternate. For flight operations at these
locations, when the WAAS avionics indicate that
LNA V/VNA V or LPV service is available, then
vertical guidance may be used to complete theapproach using the displayed level of service. Should
an outage occur during the procedure, reversion to
LNA V minima may be required. As the WAAS
coverage is expanded, the
will be removed.
NOTE−
Properly trained and approved, as required, TSO-C145()and TSO-C146() equipped users (WAAS users) with and
using approved baro-VNAV equipment may plan for
LNAV/VNAV DA at an alternate airport. Specifically au-thorized W AAS users with and using approved bar o-VNAV
equipment may also plan for RNP 0.3 DA at the alternateairport as long as the pilot has verified RNP availability
through an approved prediction program.
5−4−6. Approach Clearance
a.An aircraft which has been cleared to a holding
fix and subsequently “cleared . . . approach” has not
received new routing. Even though clearance for the
approach may have been issued prior to the aircraftreaching the holding fix, ATC would expect the pilot
to proceed via the holding fix (his/her last assigned
route), and the feeder route associated with that fix (if
AIM 10/12/17
5−4−26 Arrival Proceduresa feeder route is published on the approach chart) to
the initial approach fix (IAF) to commence the
approach. WHEN CLEARED FOR THE
APPROACH, THE PUBLISHED OFF AIRWAY
(FEEDER) ROUTES THAT LEAD FROM THEEN ROUTE STRUCTURE TO THE IAF ARE P ART
OF THE APPROACH CLEARANCE.
b.If a feeder route to an IAF begins at a fix located
along the route of flight prior to reaching the holding
fix, and clearance for an approach is issued, a pilotshould commence the approach via the published
feeder route; i.e., the aircraft would not be expected
to overfly the feeder route and return to it. The pilotis expected to commence the approach in a similar
manner at the IAF, if the IAF for the procedure is
located along the route of flight to the holding fix.
c.If a route of flight directly to the initial approach
fix is desired, it should be so stated by the controller
with phraseology to include the words “direct . . . ,”
“proceed direct” or a similar phrase which the pilotcan interpret without question. When uncertain of the
clearance, immediately query A TC as to what route of
flight is desired.
d.The name of an instrument approach, as
published, is used to identify the approach, eventhough a component of the approach aid, such as the
glideslope on an Instrument Landing System, is
inoperative or unreliable. The controller will use thename of the approach as published, but must advise
the aircraft at the time an approach clearance is issued
that the inoperative or unreliable approach aidcomponent is unusable, except when the title of the
published approach procedures otherwise allows; for
example, ILS Rwy 05 or LOC Rwy 05.
e.The following applies to aircraft on radar
vectors and/or cleared “direct to” in conjunction with
an approach clearance:
1.Maintain the last altitude assigned by ATC
until the aircraft is established on a published
segment of a transition route, or approach proceduresegment, or other published route, for which a lower
altitude is published on the chart. If already on an
established route, or approach or arrival segment, you
may descend to whatever minimum altitude is listed
for that route or segment.
2.Continue on the vector heading until
intercepting the next published ground track
applicable to the approach clearance.3.Once reaching the final approach fix via the
published segments, the pilot may continue on
approach to a landing.
4.If proceeding to an IAF with a published
course reversal (procedure turn or hold-in-lieu of PT
pattern), except when cleared for a straight inapproach by ATC, the pilot must execute the
procedure turn/hold-in-lieu of PT, and complete the
approach.
5.If cleared to an IAF/IF via a NoPT route, or
no procedure turn/hold-in-lieu of PT is published,
continue with the published approach.
6.In addition to the above, RNA V aircraft may
be issued a clearance direct to the IAF/IF at interceptangles not greater than 90 degrees for both
conventional and RNA V instrument approaches.
Controllers may issue a heading or a course direct to
a fix between the IF and FAF at intercept angles not
greater than 30 degrees for both conventional and
RNA V instrument approaches. In all cases, control-lers will assign altitudes that ensure obstacle
clearance and will permit a normal descent to the
FAF. When clearing aircraft direct to the IF, ATC willradar monitor the aircraft until the IF and will advise
the pilot to expect clearance direct to the IF at least 5
miles from the fix. ATC must issue a straight-inapproach clearance when clearing an aircraft direct to
an IAF/IF with a procedure turn or hold −in−lieu of a
procedure turn, and ATC does not want the aircraft to
execute the course reversal.
NOTE−
Refer to 14 CFR 91.175 (i).
7.RNA V aircraft may be issued a clearance
direct to the FAF that is also charted as an IAF, in
which case the pilot is expected to execute the
depicted procedure turn or hold-in-lieu of procedure
turn. ATC will not issue a straight-in approach
clearance. If the pilot desires a straight-in approach,
they must request vectors to the final approach course
outside of the FAF or fly a published “NoPT” route.
When visual approaches are in use, ATC may clear an
aircraft direct to the FAF.
NOTE−
1.In anticipation of a clearance by ATC to any fix pub-
lished on an instrument approach procedure, pilots ofRNAV aircraft are advised to select an appropriate IAF or
feeder fix when loading an instrument approach pr ocedure
into the RNAV system.
2.Selection of “V ectors-to-Final” or “V ectors” option for
an instrument approach may prevent approach fixes
AIM 10/12/17
5−4−27 Arrival Procedureslocated outside of the F AF from being loaded into an RNAV
system. Therefore, the selection of these options isdiscouraged due to increased workload for pilots to
reprogram the navigation system.
f.An RF leg is defined as a constant radius circular
path around a defined turn center that starts and
terminates at a fix. An RF leg may be published as
part of a procedure. Since not all aircraft have thecapability to fly these leg types, pilots are responsible
for knowing if they can conduct an RNA V approach
with an RF leg. Requirements for RF legs will beindicated on the approach chart in the notes section or
at the applicable initial approach fix. Controllers will
clear RNA V-equipped aircraft for instrument ap-proach procedures containing RF legs:
1.Via published transitions, or
2.In accordance with paragraph e6 above, and
3.ATC will not clear aircraft direct to any
waypoint beginning or within an RF leg, and will not
assign fix/waypoint crossing speeds in excess ofcharted speed restrictions.
EXAMPLE −
Controllers will not clear air craft direct to THIRD because
that waypoint begins the RF leg, and aircraft cannot bevectored or cleared to TURNN or vectored to intercept the
approach segment at any point between THIRD andFORTH because this is the RF leg. (See FIG 5−4−15.)
g.When necessary to cancel a previously issued
approach clearance, the c ontroller will advise the
pilot “Cancel Approach Clearance” followed by anyadditional instructions when applicable.
5−4−7. Instrument Approach Procedures
a.Aircraft approach category means a grouping of
aircraft based on a speed of V
REF, if specified, or if
VREF is not specified, 1.3 V SO at the maximum
certified landing weight. V REF, VSO, and the
maximum certified landing weight are those values as
established for the aircraft by the certification
authority of the country of registry. A pilot must use
the minima corresponding to the category determinedduring certification or higher. Helicopters may use
Category A minima. If it is necessary to operate at a
speed in excess of the upper limit of the speed rangefor an aircraft’s category, the minimums for the
higher category must be used. For example, an
airplane which fits into Category B, but is circling toland at a speed of 145 knots, must use the approach
Category D minimums. As an additional example, a
Category A airplane (or helicopter) which is
operating at 130 knots on a straight−in approach must
use the approach Category C minimums. See thefollowing category limits:
1.Category A: Speed less than 91 knots.
2.Category B: Speed 91 knots or more but less
than 121 knots.
3.Category C: Speed 121 knots or more but
less than 141 knots.
4.Category D: Speed 141 knots or more but
less than 166 knots.
5.Category E: Speed 166 knots or more.
NOTE−
VREF in the above definition refers to the speed used in
establishing the approved landing distance under theairworthiness regulations constituting the type
certification basis of the airplane, regardless of whether
that speed for a particular airplane is 1.3
VSO, 1.23 VSR, or
some higher speed required for airplane controllability.This speed, at the maximum certificated landing weight,determines the lowest applicable approach category for
all approaches regardless of actual landing weight.
b.When operating on an unpublished route or
while being radar vectored, the pilot, when an
approach clearance is received, must, in addition tocomplying with the minimum altitudes for IFR
operations (14 CFR Section 91.177), maintain the
last assigned altitude unless a different altitude isassigned by A TC, or until the aircraft is established on
a segment of a published route or IAP. After the
aircraft is so established, published altitudes apply to
descent within each succeeding route or approach
segment unless a different altitude is assigned by
ATC. Notwithstanding this pilot responsibility, foraircraft operating on unpublished routes or while
being radar vectored, ATC will, except when
conducting a radar approach, issue an IFR approachclearance only after the aircraft is established on a
segment of a published route or IAP, or assign an
altitude to maintain until the aircraft is established on
a segment of a published route or instrument
approach procedure. For this purpose, the procedure
turn of a published IAP must not be considered asegment of that IAP until the aircraft reaches the
initial fix or navigation facility upon which the
procedure turn is predicated.
AIM 10/12/17
5−4−28 Arrival ProceduresEXAMPLE −
Cross Redding VOR at or above five thousand, clearedVOR runway three four approach. or
Five miles fr om outer marker, turn right heading three three
zero, maintain two thousand until established on thelocalizer , cleared ILS runway three six approach.
NOTE−
1.The altitude assigned will assure IFR obstruction clear-
ance from the point at which the approach clearance is
issued until established on a segment of a published route
or IAP . If uncertain of the meaning of the clearance, imme-diately request clarification from ATC.
2.An aircraft is not established on an approach while
below published approach altitudes. If the MVA/MIA
allows, and ATC assigns an altitude below an IF or IAF
altitude, the pilot will be issued an altitude to maintain until
past a point that the air craft is established on the appr oach.
c.Several IAPs, using various navigation and
approach aids may be authorized for an airport. ATC
may advise that a particular approach procedure isbeing used, primarily to expedite traffic. If issued a
clearance that specifies a particular approach
procedure, notify ATC immediately if a different one
is desired. In this event it may be necessary for ATC
to withhold clearance for the different approach until
such time as traffic conditions permit. However, apilot involved in an emergency situation will be given
priority. If the pilot is not familiar with the specific
approach procedure, ATC should be advised and they
will provide detailed information on the execution of
the procedure.
REFERENCE −
AIM, Paragraph 5 −4−4 , Advance Information on Instrument Approach
d.The name of an instrument approach, as
published, is used to identify the approach, eventhough a component of the approach aid, such as the
glideslope on an Instrument Landing System, is
inoperative or unreliable. The controller will use thename of the approach as published, but must advise
the aircraft at the time an approach clearance is issued
that the inoperative or unreliable approach aid
component is unusable, except when the title of the
published approach procedures otherwise allows, for
example, ILS or LOC.
e.Except when being radar vectored to the final
approach course, when cleared for a specificallyprescribed IAP; i.e., “cleared ILS runway one niner
approach” or when “cleared approach” i.e., execution
of any procedure prescribed for the airport, pilotsmust execute the entire procedure commencing at an
IAF or an associated feeder route as described on the
IAP chart unless an appropriate new or revised ATC
clearance is received, or the IFR flight plan is
canceled.
f.Pilots planning flights to locations which are
private airfields or which have instrument approach
procedures based on private navigation aids should
obtain approval from the owner. In addition, the pilot
must be authorized by the FAA to fly special
instrument approach procedures associated with
private navigation aids (see paragraph 5 −4−8).
Owners of navigation aids that are not for public use
may elect to turn off the signal for whatever reason
they may have; for example, maintenance, energyconservation, etc. Air traffic controllers are not
required to question pilots to determine if they have
permission to land at a private airfield or to useprocedures based on privately owned navigation aids,
and they may not know the status of the navigation
aid. Controllers presume a pilot has obtainedapproval from the owner and the FAA for use of
special instrument approach procedures and is aware
of any details of the procedure if an IFR flight planwas filed to that airport.
g.Pilots should not rely on radar to identify a fix
unless the fix is indicated as “RADAR” on the IAP.
Pilots may request radar identification of an OM, but
the controller may not be able to provide the service
due either to workload or not having the fix on the
video map.
h.If a missed approach is required, advise ATC
and include the reason (unless initiated by ATC).
Comply with the missed approach instructions for the
instrument approach procedure being executed,unless otherwise directed by ATC.
REFERENCE −
AIM, Paragraph 5 −4−21 , Missed Approach
AIM, Paragraph 5 −5−5 , Missed Approach,
5−4−8. Special Instrument Approach
Procedures
Instrument Approach Procedure (IAP) charts reflect
the criteria associated with the U.S. Standard forTerminal Instrument [Approach] Procedures
(TERPs), which prescribes standardized methods for
use in developing IAPs. Standard IAPs are publishedin the Federal Register (FR) in accordance with
Title 14 of the Code of Federal Regulations, Part 97,
and are available for use by appropriately qualified
AIM 10/12/17
5−4−29 Arrival Procedurespilots operating properly equipped and airworthy
aircraft in accordance with operating rules and
procedures acceptable to the FAA. Special IAPs are
also developed using TERPS but are not given public
notice in the FR. The FAA authorizes only certainindividual pilots and/or pilots in individual
organizations to use special IAPs, and may require
additional crew training and/or aircraft equipment or
performance, and may also require the use of landing
aids, communications, or weather services not
available for public use. Additionally, IAPs thatservice private use airports or heliports are generally
special IAPs. FDC NOTAMs for Specials, FDC
T-NOTAMs, may also be used to promulgatesafety-of-flight information relating to Specials
provided the location has a valid landing area
identifier and is serviced by the United StatesNOTAM system. Pilots may access NOTAMs online
or through an FAA Flight Service Station (FSS). FSS
specialists will not automatically provide NOTAMinformation to pilots for special IAPs during
telephone pre −flight briefings. Pilots who are
authorized by the FAA to use special IAPs mustspecifically request FDC NOTAM information for
the particular special IAP they plan to use.
5−4−9. Procedure Turn and Hold −in−lieu of
Procedure Turn
a.A procedure turn is the maneuver prescribed
when it is necessary to reverse direction to establish
the aircraft inbound on an intermediate or finalapproach course. The procedure turn or hold −in−
lieu−of−PT is a required maneuver when it is depicted
on the approach chart, unless cleared by ATC for astraight−in approach. Additionally, the procedure
turn or hold−in−lieu−of−PT is not permitted when the
symbol “No PT” is depicted on the initial segmentbeing used, when a RADAR VECTOR to the final
approach course is provided, or when conducting a
timed approach from a holding fix. The altitude
prescribed for the procedure turn is a minimum
altitude until the aircraft is established on the inbound
course. The maneuver must be completed within the
distance specified in the profile view. For a
hold−in−lieu−of−PT, the holding pattern direction
must be flown as depicted and the specified leg
length/timing must not be exceeded.NOTE−
The pilot may elect to use the procedure turn orhold−in−lieu−of−PT when it is not required by the
procedure, but must first receive an amended clearance
from ATC. If the pilot is uncertain whether the ATC
clearance intends for a pr ocedure turn to be conducted or
to allow for a straight −in approach, the pilot must
immediately request clarification from ATC (14 CFRSection 91.123).
1.On U.S. Government charts, a barbed arrow
indicates the maneuvering side of the outbound
course on which the procedure turn is made.Headings are provided for course reversal using the
45 degree type procedure turn. However, the point at
which the turn may be commenced and the type andrate of turn is left to the discretion of the pilot (limited
by the charted remain within xx NM distance). Some
of the options are the 45 degree procedure turn, theracetrack pattern, the teardrop procedure turn, or the
80 degree /C0036 260 degree course reversal. Racetrack
entries should be conducted on the maneuvering side
where the majority of protected airspace resides. If an
entry places the pilot on the non −maneuvering side of
the PT, correction to intercept the outbound courseensures remaining within protected airspace. Some
procedure turns are specified by procedural track.
These turns must be flown exactly as depicted.
2.Descent to the procedure turn (PT) comple-
tion altitude from the PT fix altitude (when one has
been published or assigned by ATC) must not beginuntil crossing over the PT fix or abeam and
proceeding outbound. Some procedures contain a
note in the chart profile view that says “Maintain(altitude) or above until established outbound for
procedure turn” (See FIG 5−4−16). Newer proced-
ures will simply depict an “at or above” altitude at the
PT fix without a chart note (See FIG 5−4−17). Both
are there to ensure required obstacle clearance is
provided in the procedure turn entry zone (See
FIG 5−4−18). Absence of a chart note or specified
minimum altitude adjacent to the PT fix is anindication that descent to the procedure turn altitude
can commence immediately upon crossing over the
PT fix, regardless of the direction of flight. This isbecause the minimum altitudes in the PT entry zone
and the PT maneuvering zone are the same.
AIM 10/12/17
5−4−30 Arrival ProceduresFIG 5−4−15
Example of an RNA V Approach with RF Leg
FIG 5−4−16
FIG 5−4−17
AIM 10/12/17
5−4−31 Arrival ProceduresFIG 5−4−18
3.When the approach procedure involves a
procedure turn, a maximum speed of not greater than
200 knots (IAS) should be observed from first
overheading the course reversal IAF through the
procedure turn maneuver to ensure containmentwithin the obstruction clearance area. Pilots should
begin the outbound turn immediately after passing
the procedure turn fix. The procedure turn maneuvermust be executed within the distance specified in the
profile view. The normal procedure turn distance is
10 miles. This may be reduced to a minimum of5 miles where only Category A or helicopter aircraft
are to be operated or increased to as much as 15 miles
to accommodate high performance aircraft.4.A teardrop procedure or penetration turn may
be specified in some procedures for a required course
reversal. The teardrop procedure consists of
departure from an initial approach fix on an outbound
course followed by a turn toward and intercepting the
inbound course at or prior to the intermediate fix or
point. Its purpose is to permit an aircraft to reverse
direction and lose considerable altitude withinreasonably limited airspace. Where no fix is available
to mark the beginning of the intermediate segment, it
must be assumed to commence at a point 10 milesprior to the final approach fix. When the facility is
located on the airport, an aircraft is considered to be
on final approach upon completion of the penetrationturn. However, the final approach segment begins on
the final approach course 10 miles from the facility.
AIM 10/12/17
5−4−32 Arrival Procedures5.A holding pattern in lieu of procedure turn
may be specified for course reversal in some
procedures. In such cases, the holding pattern is
established over an intermediate fix or a final
approach fix. The holding pattern distance or timespecified in the profile view must be observed. For a
hold−in−lieu−of−PT, the holding pattern direction
must be flown as depicted and the specified leglength/timing must not be exceeded. Maximum
holding airspeed limitations as set forth for all
holding patterns apply. The holding pattern maneuver
is completed when the aircraft is established on the
inbound course after executing the appropriate entry.
If cleared for the approach prior to returning to theholding fix, and the aircraft is at the prescribed
altitude, additional circuits of the holding pattern are
not necessary nor expected by ATC. If pilots elect tomake additional circuits to lose excessive altitude or
to become better established on course, it is their
responsibility to so advise ATC upon receipt of their
approach clearance.
NOTE−
Some approach charts have an arrival holding pattern
depicted at the IAF using a “thin line” holding symbol. Itis charted where holding is frequently required prior tostarting the approach procedure so that detailed holdinginstructions are not required. The arrival holding pattern
is not authorized unless assigned by Air Traffic Control.
Holding at the same fix may also be depicted on the enr oute
chart. A hold −in−lieu of procedure turn is depicted by a
“thick line” symbol, and is part of the instrument appr oach
procedure as described in paragraph 5 −4−9. (See U. S.
Terminal Procedures booklets page E1 for both examples.)
6.A procedure turn is not required when an
approach can be made directly from a specified
intermediate fix to the final approach fix. In such
cases, the term “NoPT” is used with the appropriatecourse and altitude to denote that the procedure turn
is not required. If a procedure turn is desired, and
when cleared to do so by ATC, descent below theprocedure turn altitude should not be made until the
aircraft is established on the inbound course, since
some NoPT altitudes may be lower than theprocedure turn altitudes.
b. Limitations on Procedure Turns
1.In the case of a radar initial approach to a final
approach fix or position, or a timed approach from aholding fix, or where the procedure specifies NoPT,
no pilot may make a procedure turn unless, when final
approach clearance is received, the pilot so advisesATC and a clearance is received to execute a
procedure turn.
2.When a teardrop procedure turn is depicted
and a course reversal is required, this type turn mustbe executed.
3.When a holding pattern replaces a procedure
turn, the holding pattern must be followed, except
when RADAR VECTORING is provided or whenNoPT is shown on the approach course. The
recommended entry procedures will ensure the
aircraft remains within the holding pattern’sprotected airspace. As in the procedure turn, the
descent from the minimum holding pattern altitude to
the final approach fix altitude (when lower) may notcommence until the aircraft is established on the
inbound course. Where a holding pattern is
established in −lieu−of a procedure turn, the maxi-
mum holding pattern airspeeds apply.
REFERENCE −
AIM, Paragraph 5 −3−8 j2, Holding
4.The absence of the procedure turn barb in the
plan view indicates that a procedure turn is not
authorized for that procedure.
5−4−10. Timed Approaches from a Holding
Fix
a. TIMED APPROACHES may be conducted
when the following conditions are met:
1.A control tower is in operation at the airport
where the approaches are conducted.
2.Direct communications are maintained be-
tween the pilot and the center or approach controlleruntil the pilot is instructed to contact the tower.
3.If more than one missed approach procedure
is available, none require a course reversal.
4.If only one missed approach procedure is
available, the following conditions are met:
(a)Course reversal is not required; and,
(b)Reported ceiling and visibility are equal
to or greater than the highest prescribed circlingminimums for the IAP.
5.When cleared for the approach, pilots must
not execute a procedure turn. (14 CFR Sec-
tion 91.175.)
b.Although the controller will not specifically
state that “timed approaches are in progress,” the
AIM 10/12/17
5−4−33 Arrival Proceduresassigning of a time to depart the final approach fix
inbound (nonprecision approach) or the outer marker
or fix used in lieu of the outer marker inbound
(precision approach) is indicative that timed
approach procedures are being utilized, or in lieu ofholding, the controller may use radar vectors to the
Final Approach Course to establish a mileage interval
between aircraft that will ensure the appropriate time
sequence between the final approach fix/outer markeror fix used in lieu of the outer marker and the airport.
c.Each pilot in an approach sequence will be given
advance notice as to the time they should leave the
holding point on approach to the airport. When a time
to leave the holding point has been received, the pilot
should adjust the flight path to leave the fix as closely
as possible to the designated time. (See FIG 5 −4−19.)
AIM 10/12/17
5−4−34 Arrival ProceduresFIG 5−4−19
Timed Approaches from a Holding Fix
ONE MINUTE
FLYING TIMEAPPROXIMATELY 5 MILES
12:03 CLEARANCE RECEIVED
:04 INITIAL TIME
OVER FIX1000 FT.1000 FT.1000 FT.1000 FT.
:06 1/2
:07 REPORT
LEAVING FINALAPPROACH TIME:05 1/2:05 30 SEC.REPORT LEAVING
PREVIOUS ALTITUDE FORNEW ASSIGNED ALTITUDELMM LOM
AIRPORT
EXAMPLE −
At 12:03 local time, in the example shown, a pilot holding, receives instructions to leave the fix inbound at 12:07. Theseinstructions are r eceived just as the pilot has completed turn at the outbound end of the holding pattern and is proceeding
inbound towards the fix. Arriving back over the fix, the pilot notes that the time is 12:04 and that there are 3 minutes to lose
in order to leave the fix at the assigned time. Since the time r emaining is more than two minutes, the pilot plans to fly a rac e
track pattern rather than a 360 degree turn, which would use up 2 minutes. The turns at the ends of the race track pattern
will consume approximately 2 minutes. Three minutes to go, minus 2 minutes r equired for the turns, leaves 1 minute for level
flight. Since two portions of level flight will be r equired to get back to the fix inbound, the pilot halves the 1 minute r emaining
AIM 10/12/17
5−4−35 Arrival Proceduresand plans to fly level for 30 seconds outbound before starting the turn back to the fix on final approach. If the winds were
negligible at flight altitude, this procedure would bring the pilot inbound across the fix precisely at the specified time of12:07. However, if expecting headwind on final approach, the pilot should shorten the 30 second outbound course somewhat,
knowing that the wind will carry the aircraft away from the fix faster while outbound and decrease the ground speed while
returning to the fix. On the other hand, compensating for a tailwind on final approach, the pilot should lengthen the
calculated 30 second outbound heading somewhat, knowing that the wind would tend to hold the aircraft closer to the fixwhile outbound and increase the ground speed while returning to the fix.
5−4−11. Radar Approaches
a.The only airborne radio equipment required for
radar approaches is a functioning radio transmitterand receiver. The radar controller vectors the aircraft
to align it with the runway centerline. The controller
continues the vectors to keep the aircraft on courseuntil the pilot can complete the approach and landing
by visual reference to the surface. There are two types
of radar approaches: Precision (PAR) and Surveil-lance (ASR).
b.A radar approach may be given to any aircraft
upon request and may be offered to pilots of aircraft
in distress or to expedite traffic, however, an ASRmight not be approved unless there is an ATC
operational requirement, or in an unusual or
emergency situation. Acceptance of a P AR or ASR by
a pilot does not waive the prescribed weather
minimums for the airport or for the particular aircraft
operator concerned. The decision to make a radar
approach when the reported weather is below the
established minimums rests with the pilot.
c.PAR and ASR minimums are published on
separate pages in the FAA Terminal Procedures
Publication (TPP).
1. A PRECISION APPROACH (PAR) is one
in which a controller provides highly accuratenavigational guidance in azimuth and elevation to a
pilot. Pilots are given headings to fly, to direct them
to, and keep their aircraft aligned with the extendedcenterline of the landing runway. They are told to
anticipate glidepath interception approximately 10 to
30 seconds before it occurs and when to start descent.The published Decision Height will be given only if
the pilot requests it. If the aircraft is observed to
deviate above or below the glidepath, the pilot isgiven the relative amount of deviation by use of terms
“slightly” or “well” and is expected to adjust the
aircraft’s rate of descent/ascent to return to the
glidepath. Trend information is also issued with
respect to the elevation of the aircraft and may bemodified by the terms “rapidly” and “slowly”;
e.g., “well above glidepath, coming down rapidly.”Range from touchdown is given at least once each
mile. If an aircraft is observed by the controller to
proceed outside of specifi ed safety zone limits in
azimuth and/or elevation and continue to operate
outside these prescribed limits, the pilot will bedirected to execute a misse d approach or to fly a
specified course unless the pilot has the runway
environment (runway, approach lights, etc.) in sight.Navigational guidance in azimuth and elevation is
provided the pilot until the aircraft reaches the
published Decision Height (DH). Advisory courseand glidepath information is furnished by the
controller until the aircraft passes over the landing
threshold, at which point the pilot is advised of anydeviation from the runway centerline. Radar service
is automatically terminated upon completion of the
approach.
2. A SURVEILLANCE APPROACH (ASR)
is one in which a controller provides navigational
guidance in azimuth only. The pilot is furnished
headings to fly to align the aircraft with the extended
centerline of the landing runway. Since the radar
information used for a surveillance approach is
considerably less precise than that used for aprecision approach, the accuracy of the approach will
not be as great and higher minimums will apply.
Guidance in elevation is not possible but the pilot will
be advised when to commence descent to the
Minimum Descent Altitude (MDA) or, if appropriate,
to an intermediate step −down fix Minimum Crossing
Altitude and subsequently to the prescribed MDA. In
addition, the pilot will be advised of the location of
the Missed Approach Point (MAP) prescribed for theprocedure and the aircraft’s position each mile on
final from the runway, airport or heliport or MAP, as
appropriate. If requested by the pilot, recommendedaltitudes will be issued at each mile, based on the
descent gradient established for the procedure, down
to the last mile that is at or above the MDA. Normally,
navigational guidance will be provided until the
aircraft reaches the MAP. Controllers will terminateguidance and instruct the pilot to execute a missed
approach unless at the MAP the pilot has the runway,
AIM 10/12/17
5−4−36 Arrival Proceduresairport or heliport in sight or, for a helicopter
point−in−space approach, the prescribed visual
reference with the surface is established. Also, if, at
any time during the approach the controller considers
that safe guidance for the remainder of the approachcannot be provided, the controller will terminate
guidance and instruct the pilot to execute a missed
approach. Similarly, guidance termination andmissed approach will be effected upon pilot request
and, for civil aircraft only, controllers may terminate
guidance when the pilot reports the runway,airport/heliport or visual surface route (point −in−
space approach) in sight or otherwise indicates that
continued guidance is not required. Radar service isautomatically terminated at the completion of a radar
approach.
NOTE−
1.The published MDA for straight −in approaches will be
issued to the pilot before beginning descent. When a
surveillance approach will terminate in a circle −to−land
maneuver, the pilot must furnish the aircraft approachcategory to the contr oller. The controller will then pr ovide
the pilot with the appropriate MDA.
2.ASR APPROACHES ARE NOT AVAILABLE WHEN
AN ATC F ACILITY IS USING CENRAP .
3. A NO−GYRO APPROACH is available to
a pilot under radar control who experiences
circumstances wherein the directional gyro or otherstabilized compass is inoperative or inaccurate.
When this occurs, the pilot should so advise ATC and
request a No −Gyro vector or approach. Pilots of
aircraft not equipped with a directional gyro or other
stabilized compass who desire radar handling may
also request a No −Gyro vector or approach. The pilot
should make all turns at standard rate and should
execute the turn immediately upon receipt of
instructions. For example, “TURN RIGHT,” “STOPTURN.” When a surveillance or precision approach
is made, the pilot will be advised after the aircraft has
been turned onto final approach to make turns at half
standard rate.
5−4−12. Radar Monitoring of Instrument
Approaches
a.PAR facilities operated by the FAA and the
military services at some joint −use (civil and
military) and military installations monitor aircrafton instrument approaches and issue radar advisories
to the pilot when weather is below VFR minimums
(1,000 and 3), at night, or when requested by a pilot.This service is provided only when the PAR Final
Approach Course coincides with the final approach
of the navigational aid and only during the
operational hours of the PAR. The radar advisories
serve only as a secondary aid since the pilot hasselected the navigational aid as the primary aid for the
approach.
b.Prior to starting final approach, the pilot will be
advised of the frequency on which the advisories will
be transmitted. If, for any reason, radar advisoriescannot be furnished, the pilot will be so advised.
c.Advisory information, derived from radar
observations, includes information on:
1.Passing the final approach fix inbound
(nonprecision approach) or passing the outer marker
or fix used in lieu of the outer marker inbound(precision approach).
NOTE−
At this point, the pilot may be requested to report sighting
the approach lights or the runway.
2.Trend advisories with respect to elevation
and/or azimuth radar position and movement will beprovided.
NOTE−
Whenever the aircraft nears the P AR safety limit, the pilot
will be advised that the aircraft is well above or below the
glidepath or well left or right of course. Glidepathinformation is given only to those aircraft executing a
precision approach, such as ILS. Altitude information is
not transmitted to aircraft executing other than precision
approaches because the descent portions of theseapproaches generally do not coincide with the depictedP AR glidepath.
3.If, after repeated advisories, the aircraft
proceeds outside the PAR safety limit or if a radical
deviation is observed, the pilot will be advised toexecute a missed approach unless the prescribed
visual reference with the surface is established.
d.Radar service is automatically terminated upon
completion of the approach.
5−4−13. ILS Approaches to Parallel
Runways
a.ATC procedures permit ILS/RNA V/GLS
instrument approach operations to dual or triple
parallel runway configurations. ILS/RNA V/GLSapproaches to parallel runways are grouped into three
classes: Simultaneous Parallel Dependent Ap-
proaches; Simultaneous (Parallel) Independent
AIM 10/12/17
5−4−37 Arrival ProceduresApproaches; and Simultaneous Close Parallel PRM
Approaches. (See FIG 5 −4−20.) RNA V approach
procedures that are approved for simultaneous
operations require GPS as the sensor for position
updating. VOR/DME, DME/DME and IRU RNA V
updating is not authorized. The classification of a
parallel runway approach procedure is dependent on
adjacent parallel runway centerline separation, ATCprocedures, and airport ATC radar monitoring and
communications capabilities. At some airports one or
more parallel localizer courses may be offset up to 3degrees. ILS approaches with offset localizer
configurations result in loss of Category II/III
capabilities and an increase in decision altitude/height (50’).
b.Parallel approach operations demand height-
ened pilot situational awareness. A thorough
Approach Procedure Chart review should be
conducted with, as a minimum, emphasis on thefollowing approach chart information: name and
number of the approach, localizer frequency, inbound
localizer/azimuth course, glide slope interceptaltitude, glideslope crossing altitude at the final
approach fix, decision height, missed approach
instructions, special notes/procedures, and theassigned runway location/proximity to adjacent
runways. Pilots will be advised that simultaneous
dependent approaches, simultaneous approaches, or
simultaneous close parallel PRM approaches are in
use. This information may be provided through theATIS.
c.The close proximity of adjacent aircraft
conducting simultaneous (parallel) independent
approaches and simultaneous close parallel PRM
approaches mandates strict pilot compliance with all
ATC clearances. ATC assigned airspeeds, altitudes,
and headings must be complied with in a timely
manner. Autopilot coupled approaches require pilotknowledge of procedures necessary to comply withATC instructions. Simultaneous (parallel) independ-
ent approaches and simultaneous close parallel PRM
approaches necessitate precise approach course
tracking to minimize final monitor controller
intervention, and unwanted No Transgression Zone(NTZ) penetration. In the unlikely event of a
breakout, A TC will not assign altitudes lower than the
minimum vectoring altitude. Pilots should notifyATC immediately if there is a degradation of aircraft
or navigation systems.
d.Strict radio discipline is mandatory during
simultaneous (parallel) independent and simulta-neous close parallel PRM approach operations. This
includes an alert listening watch and the avoidance of
lengthy, unnecessary radio transmissions. Attentionmust be given to proper call sign usage to prevent the
inadvertent execution of clearances intended for
another aircraft. Use of abbreviated call signs must be
avoided to preclude confusion of aircraft with similar
sounding call signs. Pilots must be alert to unusually
long periods of silence or any unusual backgroundsounds in their radio receiver.
A stuck microphone
may block the issuance of ATC instructions on the
tower frequency by the final monitor controllerduring simultaneous (parallel) independent and
simultaneous close parallel PRM approaches. In the
case of PRM approaches, the use of a secondfrequency by the monitor controller mitigates the
“stuck mike” or other blockage on the tower
frequency.
REFERENCE −
AIM, Chapter 4, Section 2, Radio Communications Phraseology andTechniques, gives additional communications information.
e.Use of Traffic Collision Avoidance Systems
(TCAS) provides an additional element of safety to
parallel approach operations. Pilots should followrecommended TCAS operating procedures presented
in approved flight manuals, original equipment
manufacturer recommendations, professional news-letters, and FAA publications.
AIM 10/12/17
5−4−38 Arrival ProceduresFIG 5−4−20
Simultaneous Parallel Approaches
(Parallel Runways and Approach Courses and Offset Approach Courses between 2.5 and 3.0 degrees)
AIM 10/12/17
5−4−39 Arrival Procedures5−4−14. Parallel ILS Approaches (Dependent)
(See FIG 5−4−21.)
FIG 5−4−21
Simultaneous (Parallel) Dependent Approaches
a.Simultaneous (parallel) dependent approaches
are an ATC procedure permitting approaches to
airports having parallel runway centerlines separated
by between 2,500 feet and 9,000 feet. Integral parts
of a total system are ILS, radar, communications,ATC procedures, and required airborne equipment.
RNA V equipment in the aircraft or GLS equipment
on the ground and in the aircraft may replace therequired airborne and ground based ILS equipment.
b.A simultaneous (parallel) dependent approach
differs from a simultaneous (parallel) independent
approach in that, the minimum distance betweenparallel runway centerlines is reduced; there is no
requirement for radar monitoring or advisories; and
a staggered separation of aircraft on the adjacent finalcourse is required.
c.A minimum of 1.0 NM radar separation
(diagonal) is required between successive aircraft on
the adjacent final approach course when runwaycenterlines are at least 2,500 feet but no more than
3,600 feet apart. A minimum of 1.5 NM radarseparation (diagonal) is required between successive
aircraft on the adjacent final approach course when
runway centerlines are more than 3,600 feet but no
more than 8,300 feet apart. When runway centerlines
are more than 8,300 feet but no more than 9,000 feetapart a minimum of 2 NM diagonal radar separation
is provided. Aircraft on the same final approach
course within 10 NM of the runway end are provided
a minimum of 3 NM radar separation, reduced to
2.5 NM in certain circumstances. In addition, a
minimum of 1,000 feet vertical or a minimum of three
miles radar separation is provided between aircraft
during turn on to the parallel final approach course.
d.Whenever parallel approaches are in progress,
pilots are informed by ATC or via the ATIS that
approaches to both runways are in use. The chartedIAP also notes which runways may be used
simultaneously. In addition, the radar controller will
have the interphone capability of communicatingwith the tower controller where separation responsi-
bility has not been delegated to the tower.
AIM 10/12/17
5−4−40 Arrival ProceduresNOTE−
ATC will specifically identify these operations as being de-pendent when advertised on the ATIS.
EXAMPLE −
Simultaneous dependent ILS runway 19R and 19L inprogress.
e.At certain airports, simultaneous (parallel)
dependent approaches are permitted to runways
spaced less than 2500 feet apart. In this case, ATC will
stagger aircraft on the parallel approaches with theleaders always arriving on the same runway. The
trailing aircraft is permitted diagonal separation of
not less than 1.5 NM, instead of the single runwayseparation normally utilized for runways spaced less
than 2500 feet apart. For wake turbulence mitigation
reasons: a) 1.5 NM spacing is only permitted whenthe leader is either in the large or small waketurbulence category, and b) all aircraft must descend
on the glideslope from the altitude at which they were
cleared for the approach during these operations.
When 1.5 NM reduced separation is authorized, the
IAP briefing strip which indicates that simultaneousoperations require the use of vertical guidance and
that the pilot should maintain last assigned altitude
until intercepting the glideslope. No special pilottraining is required to participate in these operations.
NOTE−
Either simultaneous dependent ILS approaches or SOIALDA PRM and ILS PRM approaches may be conducted tothese runways depending on weather conditions and traffic
volume. Pilots should use caution so as not to confuse these
operations. Use SOIA procedures only when the ATIS ad-
vertises PRM approaches are in use, refer to AIMparagraph 5-4-16. SFO is the only airport where both pro-
cedures are presently conducted.
AIM 10/12/17
5−4−41 Arrival Procedures5−4−15. Simultaneous (Parallel) Independent ILS/RNAV/GLS Approaches
(See FIG 5−4−22.)
FIG 5−4−22
Simultaneous (Parallel) Independent ILS/RNA V/GLS Approaches
a. System. An approach system permitting
simultaneous ILS/RNA V/GLS approaches to parallel
runways with centerlines separated by 4,300 to
9,000 feet (9,200’ for airports above 5,000’) utilizing
NTZ final monitor controllers. Simultaneous (paral-lel) independent approaches require NTZ radar
monitoring to ensure separation between aircraft on
the adjacent parallel approach course. Aircraftposition is tracked by final monitor controllers who
will issue instructions to aircraft observed deviating
from the assigned final approach course. Staggeredradar separation procedures are not utilized. Integral
parts of a total system are ILS, radar, communica-
tions, ATC procedures, and required airborneequipment. A chart note identifies that the approach
is authorized for simultaneous use. When simultan-
eous operations are in progress, it will be advertisedon the ATIS. When advised that simultaneous
approaches are in progress, pilots must advise
approach control immediately of malfunctioning orinoperative receivers, or if a simultaneous approach
is not desired.
NOTE−
ATC does not use the word independent or parallel whenadvertising these operations on the ATIS.
EXAMPLE −
Simultaneous ILS 24L and ILS 24R approaches in
progress.
b.Radar Services. These services are is provided
for each simultaneous (parallel) independent ap-
proach.
1.During turn on to parallel final approach,
aircraft will be provided 3 miles radar separation ora minimum of 1,000 feet vertical separation. The
assigned altitude must be maintained until intercept-
ing the glide path, unless cleared otherwise by ATC.Aircraft will not be vectored to intercept the final
approach course at an angle greater than thirty
degrees.
AIM 10/12/17
5−4−42 Arrival Procedures2.The final monitor controller will have the
capability of overriding the tower controller on the
tower frequency.
3.Pilots will be instructed to contact the tower
frequency prior to the point where NTZ monitoring
begins.
4.Aircraft observed to overshoot the turn −on or
to continue on a track which will penetrate the NTZwill be instructed to return to the correct final
approach course immediately. The final monitor
controller may cancel the approach clearance, and
issue missed approach or other instructions to the
deviating aircraft.
PHRASEOLOGY −
“(Aircraft call sign) YOU HAVE CROSSED THE FINAL
APPROACH COURSE. TURN (left/right)
IMMEDIATELY AND RETURN TO THE FINALAPPROACH COURSE,”
or
“(aircraft call sign) TURN (left/right) AND RETURN TO
THE FINAL APPROACH COURSE.”5.If a deviating aircraft fails to respond to such
instructions or is observed penetrating the NTZ, the
aircraft on the adjacent final approach course (if
threatened), will be issued a breakout instruction.
PHRASEOLOGY −
“TRAFFIC ALERT (aircraft call sign) TURN (left/right)
IMMEDIATELY HEADING (degrees), (climb/descend)AND MAINTAIN (altitude).”
6.Radar monitoring will automatically be
terminated when visual separation is applied, the
aircraft reports the approach lights or runway in sight,
or the aircraft is 1 mile or less from the runwaythreshold. Final monitor controllers will not advise
pilots when radar monitoring is terminated.
NOTE−
Simultaneous independent approaches conducted to run-ways spaced greater than 9,000 feet (or 9,200’ at airportsabove 5,000’) do not require an NTZ. However, from a pi-
lot’ s perspective, the same alerts relative to deviating
aircraft will be provided by ATC as are provided when an
NTZ is being monitored. Pilots may not be aware as towhether or not an NTZ is being monitored.
AIM 10/12/17
5−4−43 Arrival Procedures5−4−16. Simultaneous Close Parallel ILS PRM/RNAV PRM/GLS PRM Approaches and
Simultaneous Offset Instrument Approaches (SOIA)(See FIG 5−4−23.)
FIG 5−4−23
PRM Approaches
Simultaneous Close Parallel
a. System.
1.PRM is an acronym for the high update rate
Precision Runway Monitor surveillance system whichis required to monitor the No Transgression Zone
(NTZ) for specific parallel runway separations used to
conduct simultaneous close parallel approaches. PRMis also published in the title as part of the approach
name for IAPs used to conduct Simultaneous Close
Parallel approaches. “PRM” alerts pilots that specific
airborne equipment, training, and procedures are
applicable.
Because Simultaneous Close Parallel PRM
approaches are independent, the NTZ and normal op-
erating zone (NOZ) airspace between the finalapproach courses is monitored by two monitor con-
trollers, one for each approach course. The NTZ
monitoring system consists of high resolution ATCradar displays, automated tracking software whichprovides monitor controllers with aircraft identifica-
tion, position, speed and a ten-second projected
position, as well as visual and aural NTZ penetration
alerts. A PRM high update rate surveillance sensor is
a component of this system only for specific runwayspacing. Additional procedures for simultaneous in-
dependent approaches are described in Paragraph
5−4−15, Simultaneous (Parallel) Independent ILS/
RNA V/GLS Approaches. Simultaneous Close
Parallel PRM approaches, whether conducted utiliz-
ing a high update rate PRM surveillance sensor or not,
must meet all of the following requirements: pilot
training, PRM in the approach title, NTZ monitoring
utilizing a final monitor aid, publication on an AAUP,
and use of a secondary PRM communication fre-
quency.
Simultaneous close parallel ILS PRM approaches are
depicted on a separate Approach Procedure Chart
AIM 10/12/17
5−4−44 Arrival Procedurestitled ILS PRM Rwy XXX (Simultaneous Close Par-
allel).
NOTE−
ATC does not use the word “independent” when advert-
ising these operations on the ATIS.
EXAMPLE −
Simultaneous ILS PRM 33L and ILS PRM 33R appr oaches
in progress.
(a)In the discussion below, RNA V PRM and
GLS PRM approaches may be substituted for one orboth of the ILS PRM approaches in a simultaneous
close parallel operation, or, in the case of SOIA, may
be substituted for an ILS PRM and/or LDA PRM ap-proach. RNA V PRM or GLS PRM approaches utilize
the same applicable chart notations and the same
fixes, crossing altitudes, and missed approach pro-
cedures as the ILS PRM or LDA PRM approach it
overlays. Vertical guidance for an RNA V PRM orGLS PRM approach must be used when substituting
for an ILS PRM or LDA PRM approach.
(b)RNA V PRM and GLS PRM approaches
may be substituted for:
(1)one or both of the ILS PRM approaches
in a simultaneous close parallel operation, or
(2)the ILS PRM and/or LDA PRM ap-
proach in a Simultaneous Offset Instrument
Approach (SOIA) operation.
(c)The pilot may request to fly the RNA V
PRM or GLS PRM approach in lieu of either the ILS
PRM and LDA PRM approaches. ATIS may advert-
ise RNA V or GLS PRM approaches to the affectedrunway or runways in the event of the loss of ground
based NA V AIDS. The Attention All Users Page will
address ILS PRM, LDA PRM, RNA V PRM, or GLS
PRM approaches as applicable. In the remainder of
this section:
(1)The RNA V PRM or GLS PRM ap-
proaches may be substituted when reference is made
to an ILS, LOC, or SOIA of fset LDA PRM approach.
(2)The RNA V PRM or GLS PRM Missed
Approach Point (MAP) in SOIA operations may besubstituted when reference is made to the LDA PRM
MAP.
2.Flight Management System (FMS) coding of
the offset RNA V PRM and GLS PRM approaches in
a SOIA operation is different than other RNA V and
GLS approach coding in that it does not match theinitial procedure published on the charted IAP. In the
SOIA design of the offset approach, the lateral course
terminates at the fictitious threshold point (FTP),
which is an extension of the final approach course to
a point near the runway threshold. The FTP isdesignated in the approach coding as the MAP so that
vertical guidance is available to the pilot to the
runway threshold, just as vertical guidance isprovided by the LDA glideslope. RNA V and GLS
lateral guidance, in contrast, is discontinued at the
charted MAP and replaced by visual maneuvering to
accomplish runway alignment in the same manner as
LDA course guidance is discontinued at the MAP.
As a result of this RNA V and GLS approach coding,
when executing a missed approach at and after
passing the charted MAP, a heading must initially be
flown, either hand-flown or using autopilot “heading
mode,” before engaging LNA V . If the pilot engages
LNAV immediately, the aircraft will continue to track
toward the FTP instead of commencing a turn toward
the missed approach holding fix. Notes on the charted
IAP and in the AAUP make specific reference to thisprocedure.
Because the SOIA LDA approach is coded in the
FMS in same manner as the RNA V GPS approach,
this same procedure should be utilized whenconducting the LDA PRM missed approach at or
inside of the LDA MAP.
Some FMSs do not code waypoints inside of the FAF
as part of the approach. Therefore, the depicted MAP
on the charted IAP may not be included in the offsetapproach coding. Pilots utilizing those FMSs may
identify the location of the waypoint by noting its
distance from the FTP as published on the chartedIAP. In those same FMSs, the straight-in SOIA
approach will not display a waypoint inside the PFAF.
The same procedures may be utilized to identify theuncoded waypoint. In this case, the location is
determined by noting its distance from the runway
waypoint as published on the charted IAP.
Because the FTP is coded as the MAP, the FMS map
display will depict the initial missed approach course
as beginning at the FTP. This depiction does not
match the charted initial missed approach procedure
on the IAP. Pilots are reminded that charted IAP
guidance is to be followed, not the map display. Once
the aircraft completes the initial turn when
AIM 10/12/17
5−4−45 Arrival Procedurescommencing a missed approach, the remainder of the
procedure coding is standard and can be utilized as
with any other IAP.
b. Simultaneous Offset Instrument Approach
(SOIA).
1.SOIA is an acronym for Simultaneous Of fset
Instrument Approach, a procedure used to conduct
simultaneous approaches to runways spaced less than
3,000 feet, but at least 750 feet apart. The SOIAprocedure utilizes an ILS PRM approach to one
runway and an of fset Localizer Type Directional Aid
(LDA) PRM approach with glide slope to the
adjacent runway. In SOIA operations, aircraft are
paired, with the aircraft conducting the ILS PRM
approach always positioned slightly ahead of the
aircraft conducting the LDA PRM approach.
2.The ILS PRM approach plates used in SOIA
operations are identical to other ILS PRM approach
plates, with an additional note, which provides theseparation between the two runways used for
simultaneous approaches. The LDA PRM approach
plate displays the required notations for closely
spaced approaches as well as depicting the visual
segment of the approach.
3.Controllers monitor the SOIA ILS PRM and
LDA PRM approaches in exactly the same manner as
is done for ILS PRM approaches. The procedures and
system requirements for SOIA ILS PRM and LDA
PRM approaches are identical with those used forsimultaneous close parallel ILS PRM approaches
until near the LDA PRM approach missed approach
point (MAP) −− where visual acquisition of the ILS
aircraft by the aircraft conducting the LDA PRMapproach occurs. Since the ILS PRM and LDA PRM
approaches are identical except for the visual segment
in the SOIA concept, an understanding of the
procedures for conducting ILS PRM approaches isessential before conducting a SOIA ILS PRM or
LDA PRM operation.
4.In SOIA, the approach course separation
(instead of the runway separation) meets established
close parallel approach criteria. Refer toFIG 5− 4−24 for the generic SOIA approach geo-
metry. A visual segment of the LDA PRM approachis established betwe en the LDA MAP and the runway
threshold. Aircraft transition in visual conditions
from the LDA course, beginning at the LDA MAP, to
align with the runway and can be stabilized by 500feet above ground level (AGL) on the extendedrunway centerline. Aircraft will be “paired” in SOIA
operations, with the ILS aircraft ahead of the LDA
aircraft prior to the LDA aircraft reaching the LDA
MAP. A cloud ceiling for the approach is establishedso that the LDA aircraft has nominally 30 seconds to
acquire the leading ILS aircraft prior to the LDA
aircraft reaching the LDA MAP. If visual acquisition
is not accomplished, a missed approach must be
executed at the LDA MAP.
c. Requirements and Procedures.
Besides system requirements and pilot procedures as
identified in subparagraph a1 above, all pilots musthave completed special training before accepting a
clearance to conduct ILS PRM or LDA PRM Simul-
taneous Close Parallel Approaches.
1. Pilot Training Requirement. Pilots must
complete special pilot training , as outlined below,
before accepting a clearance for a simultaneous close
parallel ILS PRM or LDA PRM approach.
(a)For operations under 14 CFR Parts 121,
129, and 135, pilots must comply with FAA− ap-
proved company training as identified in theirOperations S
pecifications. Training, at a minim-
um, must require pilots to view the FAA video
“ILS PRM AND SOIA APPROACHES: INFORM-
ATION FOR AIR CARRIER PILOTS.” Refer tohttps://www.faa.gov/ training_testing/training/
prm/ or search key words FAA PRM for
additional information and to view or download the
video.
(b)For operations under Part 91:
(1)Pilots operating transport category
aircraft must be familiar with PRM operations as con-
tained in this section of the AIM. In addition, pilots
operating transport category aircraft must view
the FAA video “ILS PRM AND SOIAAPPROACHES: INFORMATION FOR AIR
CARRIER PILOTS.” Refer to https://www.faa.gov/
training_testing/training/prm/ or search key
words FAA PRM for additional information and to
view or download the video.
(2)Pilots not operating transport cat-
egory aircraft must be familiar with PRM and SOIA
operations as contained in this section of the AIM.The FAA strongly recommends that pilots not in-
volved in transport category aircraft operations
view the FAA video, “ILS PRM AND SOIA AP-
AIM 10/12/17
5−4−46 Arrival ProceduresPROACHES: INFORMATION FOR GENERAL
A VIATION PILOTS.” Refer to
https://www.faa.gov/ training_testing/training/
prm/ or search key words FAA PRM for
additional information and to view or download thevideo.
NOTE−
Either simultaneous dependent ILS approaches, or SOIALDA PRM and ILS PRM approaches may be conducted de-
pending on weather conditions and traffic volume. Pilots
should use caution so as not to confuse these operations.
Use SOIA pr ocedures only when the A TIS advertises PRM
approaches are in use. For simultaneous (parallel) de-pendent approaches see paragraph 5−4−14. SFO is theonly airport where both procedures are presently conduc-ted.
2. ATC Directed Breakout. An A TC directed
“breakout” is defined as a vector off the ILS or LDA
approach course of a threatened aircraft in response to
another aircraft penetrating the NTZ.
3. Dual Communications. The aircraft flying
the ILS PRM or LDA PRM approach must have the
capability of enabling the pilot/s to listen to two
communications frequencies simultaneously.
4. Radar Services.
(a)During turn on to parallel final approach,
aircraft will be provided 3 miles radar separation ora minimum of 1,000 feet vertical separation. The as-
signed altitude must be maintained until intercepting
the glide path, unless cleared otherwise by ATC. Air-
craft will not be vectored to intercept the final
approach course at an angle greater than thirty de-grees.
(b)The final monitor controller will have the
capability of overriding the tower controller on the
tower frequency.
(c)Pilots will be instructed to contact the
tower frequency prior to the point where NTZ monit-
oring begins. Pilots will begin monitoring the
secondary PRM frequency at that time (see Dual
VHF Communications Required below).(d)To ensure separation is maintained, and in
order to avoid an imminent situation during simultan-
eous close parallel ILS PRM or SOIA ILS PRM and
LDA PRM approaches, pilots must immediately com-
ply with PRM monitor controller instructions.
(e)Aircraft observed to overshoot the turn or
to continue on a track which will penetrate the NTZ
will be instructed to return to the correct final ap-
proach course immediately. The final monitorcontroller may cancel the approach clearance, and is-
sue missed approach or other instructions to thedeviating aircraft.
PHRASEOLOGY−
“(Aircraft call sign) YOU HAVE CROSSED THE FINAL
APPROACH COURSE. TURN (le ft/right) IMMEDI-
ATELY AND RETURN TO THE LOCALIZER FINAL
APPROACH COURSE,”or“(aircraft call sign) TURN (left/right) AND RETURN TO
THE LOCALIZER FINAL APPROACH COURSE.”
(f)If a deviating aircraft fails to respond to
such instructions or is observed penetrating the NTZ,
the aircraft on the adjacent final approach course (ifthreatened) will be issued a breakout instruction.
PHRASEOLOGY−
“TRAFFIC ALERT (aircraft call sign) TURN (left/right)IMMEDIATELY HEADING (degrees), (climb/descend)AND MAINTAIN (altitude).”
(g)Radar monitoring will automatically be
terminated when visual separation is applied or the
aircraft reports the approach lights or runway in
sight. Otherwise, monitoring continues to at least
.5 NM beyond the furthest DER. Final monitor con-trollers will not advise pilots when radar monitoring
is terminated.
5.At airports that conduct PRM operations,
(ILS PRM, and the case of airports where SOIAs areconducted, ILS PRM and LDA PRM approaches) the
Attention All Users Page (AAUP) informs pilots who
are unable to participate that they will be affordedappropriate arrival services as operational conditions
permit and must notify the controlling ARTCC assoon as practical, but at least 100 miles from
destination.
AIM 10/12/17
5−4−47 Arrival ProceduresFIG 5−4−24
SOIA Approach Geometry
NOTE−
SAP The stabilized approach point is a design point along the extended centerline of the intended land-
ing runway on the glide slope/glide path at 500 feet above the runway threshold elevation. It is
used to verify a sufficient distance is provided for the visual maneuver after the offset course ap-
proach DA to permit the pilots to conform to approved, stabilized approach criteria. The SAP is
not published on the IAP .
Offset
Course DAThe point along the LDA, or other offset course, where the course separation with the adjacent
ILS, or other straight-in course, reaches the minimum distance permitted to conduct closely
spaced approaches. Typically that minimum distance will be 3,000 feet without the use of highupdate radar; with high update radar, course separation of less than 3,000 ft may be used when
validated by a safety study. The altitude of the glide slope/glide path at that point determines the
offset course approach decision altitude and is where the NTZ terminates. Maneuvering inside
the DA is done in visual conditions.
Visual
Segment
AngleAngle, as determined by the SOIA design tool, formed by the extension of the straight segment
of the calculated flight track (between the offset course MAP/DA and the SAP) and the extended
runway centerline. The size of the angle is dependent on the aircraft approach categories (Cat-egory D or only selected categories/speeds) that are authorized to use the offset course appr oach
and the spacing between the runways.
Visibility Distance from the offset course approach DA to runway threshold in statute mile .
AIM 10/12/17
5−4−48 Arrival ProceduresProcedure The aircraft on the offset course approach must see the runway-landing environment and, if ATC
has advised that traffic on the straight-in approach is a factor, the offset course approach air craft
must visually acquire the straight-in appr oach aircraft and r eport it in sight to ATC prior to r each-
ing the DA for the offset course approach.
CC The Clear of Clouds point is the position on the offset final approach course where aircraft
first operate in visual meteorological conditions below the ceiling, when the actual weather
conditions are at, or near, the minimum ceiling for SOIA operations. Ceiling is defined by theAeronautical Information Manual.
d. Attention All Users Page (AAUP). Multiple
PRM approach charts at the same airport have a single
AAUP associated with them that must be referred to
in preparation for conducting the approach.
Bullet points are published which summarize the
PRM procedures which apply to each approach and
must be briefed before conducting a PRM approach.The following information may be summarized in the
bullet points or published in more detail in the Expan-
ded Procedures section of the AAUP. Briefing on theExpanded Procedures is optional.
1. ATIS. When the ATIS broadcast advises ILS
PRM approaches are in progress (or ILS PRM and
LDA PRM approaches in the case of SOIA), pilots
should brief to fly the ILS PRM or LDA PRMapproach. If later advised to expect the ILS or LDA
approach (should one be published), the ILS PRM or
LDA PRM chart may be used after completing thefollowing briefing items. The pilot may also request
to fly the RNA V (GPS) PRM in lieu of either the ILS
PRM or LDAPRM approach. In the event of the loss
of ground based NA V AIDS, the ATIS may advertise
RNA V (GPS) PRM approaches to the affectedrunway or runways.
(a)Minimums and missed approach proced-
ures are unchanged.
(b)PRM Monitor frequency no longer re-
quired.
(c)ATC may assign a lower altitude for glide
slope intercept.
NOTE−
In the case of the LDA PRM approach, this briefing pr oced-
ure only applies if an LDA-DME approach is also
published.
In the case of the SOIA ILS PRM and LDA PRM pro-
cedure, the AAUP describes the weather conditions
in which simultaneous approaches are authorized:Simultaneous approach weather minimums are
X,XXX feet (ceiling), x miles (visibility).
2. Dual VHF Communications Re quired.
To avoid blocked transmissions, each runway will
have two frequencies, a primary and a PRM monitorfrequency. The tower controller will transmit on both
frequencies. The monitor controller’s transmissions,
if needed, will override both frequencies. Pilots willONLY transmit on the tower controller’s frequency,
but will listen to both frequencies. Select the PRM
monitor frequency audio only when instructed byATC to contact the tower. The volume levels should
be set about the same on both radios so that the pilots
will be able to hear transmissions on at least onefrequency if the other is blocked. Site specific
procedures take precedence over the general
information presented in this paragraph. Refer to the
AAUP for applicable procedures at specific airports.
NOTE−
At SFO, pilots conducting SOIA operations select the mon-itor frequency audio when communicating with the finalradar controller. In this special case, the monitor control-ler’ s transmissions, if required, override the final
controller’ s frequency.
3. Breakouts. Breakouts differ from other types
of abandoned approaches in that they can happenanywhere and unexpectedly. Pilots directed by ATC
to break off an approach must assume that an ai rcraft
is blundering toward them and a breakout must be
initiated immediately .
(a) Hand-fly breakouts. All breakouts are
to be hand-flown to ensure the maneuver is accom-
plished in the shortest amount of time.
(b) ATC Directed “Breakouts.” ATC dir-
ected breakouts will consist of a turn and a climb or
descent. Pilots must always initiate the breakout in re-
sponse to an air traffic controller’s instruction.Controllers will give a descending breakout only
when there are no other reasonable options available,
but in no case will the descent be below the minimum
AIM 10/12/17
5−4−49 Arrival Proceduresvectoring altitude (MV A) which provides at least
1,000 feet required obstruction clearance. The
AAUP may provide the MV A in the final approach
segment as X,XXX feet at (Name) Airport.
NOTE−
“TRAFFIC ALERT.” If an aircraft enters the “NO TRANS-GRESSION ZONE (NTZ),” the controller will breakout thethreatened air craft on the adjacent approach. The phraseo-
logy for the breakout will be:
PHRASEOLOGY −
TRAFFIC ALERT, (aircraft call sign) TURN (left/right)IMMEDIATELY, HEADING (degrees), CLIMB/ DES-
CEND AND MAINTAIN (altitude).
4. ILS PRM Glideslope Navigation. The pilot
may find crossing altitudes published along the final
approach course. If the approach geometry warrants
it, the pilot is advised on the AAUP that descendingon the ILS or LDA glideslope ensures complying
with any charted crossing restrictions.
5. SOIA and ILS PRM differences as noted
on the AAUP.
(a) ILS PRM, LDA T raffic (only published
on the AAUP when the ILS PRM approach is used
in conjunction with an LDA PRM approach to the
adjacent runway). To provide better situational
awareness, and because traffic on the LDA may bevisible on the ILS aircraft’s TCAS, pilots are re-
minded of the fact that aircraft will be maneuvering
behind them to align with the adjacent runway. While
conducting the ILS PRM approach to Runway XXX,
other aircraft may be c onducting the offset LDA PRM
approach to Runway XXX. These aircraft will ap-
proach from the (left/right) rear and will realign with
Runway XXX after making visual contact with theILS traffic. Under normal circumstances, these air-
craft will not pass the ILS traffic.
(b) SOIA LDA PRM Items. The AAUP sec-
tion for the SOIA LDA PRM approach contains most
information found in the ILS PRM section. It replaces
certain information as seen below and provides pilots
with the procedures to be used in the visual segmentof the LDA PRM approach from the LDA MAP until
landing.
(c) SOIA LDA PRM Navigation (replaces
ILS PRM (4) and (a) above). The pilot may find
crossing altitudes published along the final approach
course. The pilot is advised that descending on the
LDA glideslope ensures complying with any charted
crossing restrictions. Remain on the LDA course un-til passing XXXXX (LDA MAP name) intersection
prior to maneuvering to align with the centerline of
Runway XXX.
(d) SOIA (Name) Airport Visual Segment
(replaces ILS PRM (4) above). Pilot procedures for
navigating beyond the LDA MAP are spelled out. If
ATC advises that there is traffic on the adjacent ILS,
pilots are authorized to continue past the LDA MAPto align with runway centerline when:
(1)the ILS traffic is in sight and is expected
to remain in sight,
(2)ATC has been advised that “traffic is in
sight.” (ATC is not required to acknowledge this
transmission),
(3)the runway environment is in sight.
Otherwise, a missed approach must be executed.
Between the LDA MAP and the runway threshold, pi-lots conducting the LDA PRM approach are re-
sponsible for separating themselves visually from
traffic conducting the ILS PRM approach to the adja-
cent runway, which means maneuvering the aircraft
as necessary to avoid that traffic until landing, and
providing wake turbulence avoidance, if applicable.Pilots maintaining visual separation should advise
ATC, as soon as practical, if visual contact with the
aircraft conducting the ILS PRM approach is lost and
execute a missed approach unless otherwise instruc-
ted by ATC.
e. Differences between Simultaneous ILS and
ILS PRM or LDA PRM approaches of import-
ance to the pilot.
1. Runway Spacing. Prior to simultaneous
close parallel approaches, most ATC directed break-
outs were the res ult of two aircraft in-trail on the same
final approach course getting too close together. Two
aircraft going in the same direction did not mandate
quick reaction times. With PRM closely spaced ap-proaches, two aircraft could be alongside each other,
navigating on courses that are separated by less than
4,300 feet. In the unlikely event that an aircraft “blun-
ders” off its course and makes a worst case turn of 30
degrees toward the adjacent final approach course,
closing speeds of 135 feet per second could occur that
constitute the need for quick reaction. A blunder has
to be recognized by the monitor controller, and
breakout instructions issued to the endangered air-craft. The pilot will not have any warning that a
breakout is imminent because the blundering air-
craft will be on another frequency. It is important
AIM 10/12/17
5−4−50 Arrival Proceduresthat, when a pilot receives breakout instructions, he/
she assumes that a bl undering aircraft is about to or
has penetrated the NTZ and is heading toward his/her
approach course. The pilot must initiate a breakout
as soon as safety allows. While conducting PRM ap-proaches, pilots must maintain an increased sense of
awareness in order to immediately react to an ATC in-
struction ( breakout ) and maneuver as instructed by
ATC, away from a blundering aircraft.
2. Communications. To help in avoiding
communication problems caused by stuck micro-
phones and two parties talking at the same time, twofrequencies for each runway will be in use during ILS
PRM and LDA PRM approach operations, the
primary tower frequency and the PRM monitor
frequency. The tower controller transmits and receive
in a normal fashion on the primary frequency andalso transmits on the PRM monitor frequency. The
monitor controller’s transmissions override on
both frequencies. The pilots flying the approach willlisten to both frequencies but only transmit on the
primary tower frequency. If the PRM monitor
controller initiates a breakout and the primaryfrequency is blocked by another transmission, the
breakout instruction will still be heard on the PRM
monitor frequency.
NOTE−
At some airports, the override capability may be on otherthan the tower frequency (KSFO overrides the final radarcontroller frequency). Pilots should carefully review the
dual communications requirements on the AAUP prior to
accepting a PRM approach.
3. Breakouts. The probability is extremely
low that an aircraft will “blunder” from its assignedapproach course and enter the NTZ, causing ATC to
“breakout” the aircraft approaching on the adjacent
ILS or LDA course. However, because of the closeproximity of the final approach courses, it is essential
that pilots follow the ATC breakout instructions
precisely and expeditiously. The controller’s “break-
out” instructions provide conflict resolution for
the threatened aircraft, with the turn portion of the
“breakout” being the single most important elementin achieving maximum protection. A descending
breakout will only be issued when it is the only
controller option. In no case will the controllerdescend an aircraft below the MVA, which will
provide at least 1,000 feet clearance above obstacles.
The pilot is not expected to exceed 1,000 feet perminute rate of descent in the event a descending
breakout is issued.
4. Hand-flown Breakouts. The use of the
autopilot is encouraged while flying an ILS PRM or
LDA PRM approach, but the autopilot must be
disengaged in the rare event that a breakout is issued.
Simulation studies of breakouts have shown that a
hand-flown breakout can be initiated consistently
faster than a breakout performed using the autopilot.
5. TCAS. The ATC breakout instruction is the
primary means of conflict resolution. TCAS, if
installed, provides another form of conflict resolution
in the unlikely event other separation standards
would fail. TCAS is not required to conduct a closely
spaced approach.
The TCAS provides only vertical resolution of air-
craft conflicts, while the ATC breakout instruction
provides both vertical and horizontal guidance for
conflict resolutions. Pilots should always immedi-ately follow the TCAS Resolution Advisory (RA),
whenever it is received. Should a TCAS RA be re-
ceived before, during, or after an ATC breakoutinstruction is issued, the pilot should follow the RA,
even if it conflicts with the climb/descent portion of
the breakout maneuver. If following an RA requires
deviating from an ATC clearance, the pilot must ad-
vise ATC as soon as practical. While following anRA, it is extremely important that the pilot also
comply with the turn portion of the ATC breakout in-
struction unless the pilot determines safety to befactor. Adhering to these procedures assures the pilot
that acceptable “breakout” separation margins will
always be provided, even in the face of a normal pro-
cedural or system failure.
5−4−17. Simultaneous Converging
Instrument Approaches
a.ATC may conduct instrument approaches
simultaneously to converging runways; i.e., runways
having an included angle from 15 to 100 degrees, at
airports where a program has been specifically
approved to do so.
b.The basic concept requires that dedicated,
separate standard instrument approach procedures be
developed for each converging runway included.
These approaches can be identified by the letter “V”in the title; for example, “ILS V Rwy 17
(CONVERGING)”. Missed Approach Points must
be at least 3 miles apart and missed approach
AIM 10/12/17
5−4−51 Arrival Proceduresprocedures ensure that missed approach protected
airspace does not overlap.
c.Other requirements are: radar availability,
nonintersecting final approach courses, precisionapproach capability for each runway and, if runways
intersect, controllers must be able to apply visual
separation as well as intersecting runway separation
criteria. Intersecting runways also require minimums
of at least 700 foot ceilings and 2 miles visibility.Straight in approaches and landings must be made.
d.Whenever simultaneous converging ap-
proaches are in progress, aircraft will be informed by
the controller as soon as feasible after initial contactor via ATIS. Additionally, the radar controller will
have direct communications capability with the tower
controller where separation responsibility has notbeen delegated to the tower.
5−4−18. RNP AR Instrument Approach
Procedures
These procedures require authorization analogous to
the special authorization required for Category II orIII ILS procedures. Authorization required (AR)
procedures are to be conducted by aircrews meeting
special training requirements in aircraft that meet the
specified performance and functional requirements.
a. Unique characteristics of RNP AR Ap-
proaches
1. RNP value. Each published line of minima
has an associated RNP value. The indicated valuedefines the lateral and vertical performance require-
ments. A minimum RNP type is documented as part
of the RNP AR authorization for each operator andmay vary depending on aircraft configuration or
operational procedures (e.g., GPS inoperative, use of
flight director vice autopilot).
2. Curved path procedures. Some RNP ap-
proaches have a curved path, also called a
radius−to−a−fix (RF) leg. Since not all aircraft have
the capability to fly these arcs, pilots are responsiblefor knowing if they can conduct an RNP approach
with an arc or not. Aircraft speeds, winds and bank
angles have been taken into consideration in the
development of the procedures.
3. RNP required for extraction or not.
Where required, the missed approach procedure may
use RNP values less than RNP −1. The reliability of
the navigation system has to be very high in order to
conduct these approaches. Operation on these
procedures generally requires redundant equipment,as no single point of failure can cause loss of both
approach and missed approach navigation.
4. Non−standard speeds or climb gradients.
RNP AR approaches are developed based on standard
approach speeds and a 200 ft/NM climb gradient inthe missed approach. Any exceptions to these
standards will be indicated on the approach
procedure, and the operator should ensure they cancomply with any published restrictions before
conducting the operation.
5. Temperature Limits. For aircraft using
barometric vertical navigation (without temperature
compensation) to conduct the approach, low andhigh−temperature limits are identified on the
procedure. Cold temperatures reduce the glidepath
angle while high temperatures increase the glidepathangle. Aircraft using baro VNA V with temperature
compensation or aircraft using an alternate means for
vertical guidance (e.g., SBAS) may disregard thetemperature restrictions. The charted temperature
limits are evaluated for the final approach segment
only. Regardless of charted temperature limits ortemperature compensation by the FMS, the pilot may
need to manually compensate for cold temperature on
minimum altitudes and the decision altitude.
6. Aircraft size. The achieved minimums may
be dependent on aircraft size. Large aircraft mayrequire higher minimums due to gear height and/or
wingspan. Approach procedure charts will be
annotated with applicable aircraft size restrictions.
AIM 10/12/17
5−4−52 Arrival Proceduresb. Types of RNP AR Approach Operations
1. RNP Stand −alone Approach Operations.
RNP AR procedures can provide access to runways
regardless of the ground −based NA V AID infrastruc-
ture, and can be designed to avoid obstacles, terrain,
airspace, or resolve environmental constraints.
2. RNP Parallel Approach (RPA) Opera-
tions. RNP AR procedures can be used for parallel
approaches where the runway separation is adequate
(See FIG 5−4−25). Parallel approach procedures can
be used either simultaneously or as stand −alone
operations. They may be part of either independent or
dependent operations depending on the ATC ability
to provide radar monitoring.
FIG 5−4−25
3. RNP Parallel Approach Runway Transi-
tions (RPAT) Operations. RPAT approaches begin
as a parallel IFR approach operation using
simultaneous independent or dependent procedures.(See FIG 5−4−26). Visual separation standards are
used in the final segment of the approach after the
final approach fix, to permit the RPAT aircraft totransition in visual conditions along a predefined
lateral and vertical path to align with the runway
centerline.FIG 5−4−26
4. RNP Converging Runway Operations. At
airports where runways converge, but may or may not
intersect, an RNP AR approach can provide a precise
curved missed approach path that conforms to aircraft
separation minimums for simultaneous operations
(See FIG 5 −4−27). By flying this curved missed
approach path with high accuracy and containment
provided by RNP, dual runway operations may
continue to be used to lower ceiling and visibilityvalues than currently available. This type of
operation allows greater capacity at airports where it
can be applied.
FIG 5−4−27
AIM 10/12/17
5−4−53 Arrival Procedures5−4−19. Side −step Maneuver
a.ATC may authorize a standard instrument
approach procedure which serves either one ofparallel runways that are separated by 1,200 feet or
less followed by a straight −in landing on the adjacent
runway.
b.Aircraft that will execute a side −step maneuver
will be cleared for a specified approach procedure
and landing on the adjacent parallel runway.
Example, “cleared ILS runway 7 left approach,side−step to runway 7 right.” Pilots are expected to
commence the side −step maneuver as soon as
possible after the runway or runway environment isin sight. Compliance with minimum altitudes
associated with stepdown fixes is expected even after
the side−step maneuver is initiated.
NOTE−
Side−step minima are flown to a Minimum Descent
Altitude (MDA) regardless of the approach authorized.
c.Landing minimums to the adjacent runway will
be based on nonprecision criteria and therefore higher
than the precision minimums to the primary runway,
but will normally be lower than the published circlingminimums.
5−4−20. Approach and Landing Minimums
a. Landing Minimums. The rules applicable to
landing minimums are contained in 14 CFR
Section 91.175. TBL 5 −4−1 may be used to convert
RVR to ground or flight visibility. For converting
RVR values that fall between listed values, use the
next higher RVR value; do not interpolate. Forexample, when converting 1800 RVR, use 2400 RVR
with the resultant visibility of
1/2mile.
b. Obstacle Clearance. Final approach obstacle
clearance is provided from the start of the finalsegment to the runway or missed approach point,
whichever occurs last. Side −step obstacle protection
is provided by increasing the width of the finalapproach obstacle clearance area.TBL 5−4−1
RVR Value Conversions
RVR Visibility
(statute miles)
16001/4
24001/2
32005/8
40003/4
45007/8
6000 1 1/4
1.Circling approach protected areas are defined
by the tangential connection of arcs drawn from eachrunway end (see FIG 5 −4−28). Circling approach
protected areas developed prior to late 2012 used
fixed radius distances, dependent on aircraftapproach category, as shown in the table on page B2
of the U.S. TPP. The approaches using standard
circling approach areas can be identified by the
absence of the “negative C” symbol on the circling
line of minima. Circling approach protected areasdeveloped after late 2012 use the radius distance
shown in the table on page B2 of the U.S. TPP,
dependent on aircraft approach category, and thealtitude of the circling MDA, which accounts for true
airspeed increase with altitude. The approaches using
expanded circling approach areas can be identified by
the presence of the “negative C” symbol on the
circling line of minima (see FIG 5 −4−29). Because of
obstacles near the airport, a portion of the circlingarea may be restricted by a procedural note; for
example, “Circling NA E of RWY 17 −35.” Obstacle
clearance is provided at the published minimums(MDA) for the pilot who makes a straight −in
approach, side −steps, or circles. Once below the
MDA the pilot must see and avoid obstacles.Executing the missed approach after starting to
maneuver usually places the aircraft beyond the
MAP. The aircraft is clear of obstacles when at orabove the MDA while inside the circling area, but
simply joining the missed approach ground track
from the circling maneuver may not provide vertical
obstacle clearance once the aircraft exits the circling
area. Additional climb inside the circling area may be
required before joining the missed approach track.
See Paragraph 5 −4−21, Missed Approach, for
additional considerations when starting a missedapproach at other than the MAP.
AIM 10/12/17
5−4−54 Arrival ProceduresFIG 5−4−28
Final Approach Obstacle Clearance
NOTE−
Circling approach area radii vary according to appr oach category and MSL circling altitude due to TAS changes −
see FIG 5 −4−29.
FIG 5−4−29
Standard and Expanded Circling Approach Radii in the U.S. TPP
AIM 10/12/17
5−4−55 Arrival Procedures2. Precision Obstacle Free Zone (POFZ). A
volume of airspace above an area beginning at the
runway threshold, at the threshold elevation, and
centered on the extended runway centerline. The
POFZ is 200 feet (60m) long and 800 feet (240m)wide. The POFZ must be clear when an aircraft on a
vertically guided final approach is within 2 nautical
miles of the runway threshold and the of ficial weather
observation is a ceiling below 250 feet or visibility
less than 3/4 statute mile (SM) (or runway visual rangebelow 4,000 feet). If the POFZ is not clear, the
MINIMUM authorized height above touchdown
(HAT) and visibility is 250 feet and 3/4 SM. The POFZ
is considered clear even if the wing of the aircraft
holding on a taxiway waiting for runway clearancepenetrates the POFZ; however, neither the fuselage
nor the tail may infringe on the POFZ. The POFZ is
applicable at all runway ends including displaced
thresholds.
FIG 5−4−30
Precision Obstacle Free Zone (POFZ)
c. Straight −in Minimums are shown on the IAP
when the final approach course is within 30 degrees
of the runway alignment (15 degrees for GPS IAPs)
and a normal descent can be made from the IFR
altitude shown on the IAP to the runway surface.When either the normal rate of descent or the runway
alignment factor of 30 degrees (15 degrees for GPS
IAPs) is exceeded, a straight −in minimum is not
published and a circling minimum applies. The fact
that a straight −in minimum is not published does not
preclude pilots from landing straight −in if they have
the active runway in sight and have sufficient time tomake a normal approach for landing. Under such
conditions and when ATC has cleared them for
landing on that runway, pilots are not expected to
circle even though only circling minimums are
published. If they desire to circle, they should advise
ATC.
d. Side−Step Maneuver Minimums. Landing
minimums for a side −step maneuver to the adjacent
runway will normally be higher than the minimumsto the primary runway.
AIM 10/12/17
5−4−56 Arrival Procedurese. Published Approach Minimums. Approach
minimums are published for different aircraft
categories and consist of a minimum altitude (DA,
DH, MDA) and required visibility. These minimums
are determined by applying the appropriate TERPScriteria. When a fix is incorporated in a nonprecision
final segment, two sets of minimums may be
published: one for the pilot that is able to identify the
fix, and a second for the pilot that cannot. Two sets of
minimums may also be published when a second
altimeter source is used in the procedure. When anonprecision procedure incorporates both a step-
down fix in the final segment and a second altimeter
source, two sets of minimums are published toaccount for the stepdown fix and a note addresses
minimums for the second altimeter source.
f. Circling Minimums. In some busy terminal
areas, ATC may not allow circling and circling
minimums will not be published. Published circlingminimums provide obstacle clearance when pilots
remain within the appropriate area of protection.
Pilots should remain at or above the circling altitudeuntil the aircraft is continuously in a position from
which a descent to a landing on the intended runway
can be made at a normal rate of descent using normalmaneuvers. Circling may require maneuvers at low
altitude, at low airspeed, and in marginal weather
conditions. Pilots must use sound judgment, have an
indepth knowledge of their capabilities, and fully
understand the aircraft performance to determine the
exact circling maneuver since weather, unique airport
design, and the aircraft position, altitude, and
airspeed must all be considered. The following basic
rules apply:
1.Maneuver the shortest path to the base or
downwind leg, as appropriate, considering existingweather conditions. There is no restriction from
passing over the airport or other runways.
2.It should be recognized that circling
maneuvers may be made while VFR or other flying
is in progress at the airport. Standard left turns orspecific instruction from the controller for maneuver-
ing must be considered when circling to land.
3.At airports without a control tower, it may be
desirable to fly over the airport to observe wind and
turn indicators and other traffic which may be on the
runway or flying in the vicinity of the airport.REFERENCE −
AC 90−66A, Recommended Standards T raffic patterns for Aeronautical
Operations at Airports without Operating Control Towers.
4.The missed approach point (MAP) varies
depending upon the approach flown. For vertically
guided approaches, the MAP is at the decision
altitude/decision height. Non −vertically guided and
circling procedures share the same MAP and the pilot
determines this MAP by timing from the final
approach fix, by a fix, a NA V AID, or a waypoint.Circling from a GLS, an ILS without a localizer line
of minima or an RNA V (GPS) approach without an
LNA V line of minima is prohibited.
g. Instrument Approach at a Military Field.
When instrument approaches are conducted by civil
aircraft at military airports, they must be conducted in
accordance with the procedures and minimumsapproved by the military agency having jurisdiction
over the airport.
5−4−21. Missed Approach
a.When a landing cannot be accomplished, advise
ATC and, upon reaching the missed approach point
defined on the approach procedure chart, the pilot
must comply with the missed approach instructionsfor the procedure being used or with an alternate
missed approach procedure specified by ATC.
b.Obstacle protection for missed approach is
predicated on the missed approach being initiated atthe decision altitude/height (DA/H) or at the missed
approach point and not lower than minimum descent
altitude (MDA). A climb gradient of at least 200 feetper nautical mile is required, (except for Copter
approaches, where a climb of at least 400 feet per
nautical mile is required), unless a higher climbgradient is published in the notes section of the
approach procedure chart. When higher than standard
climb gradients are specified, the end point of thenon−standard climb will be specified at either an
altitude or a fix. Pilots must preplan to ensure that the
aircraft can meet the climb gradient (expressed in feet
per nautical mile) required by the procedure in the
event of a missed approach, and be aware that flying
at a higher than anticipated ground speed increasesthe climb rate requirement (feet per minute). Tables
for the conversion of climb gradients (feet per
nautical mile) to climb rate (feet per minute), basedon ground speed, are included on page D1 of the U.S.
Terminal Procedures booklets. Reasonable buffers
are provided for normal maneuvers. However, no
AIM 10/12/17
5−4−57 Arrival Proceduresconsideration is given to an abnormally early turn.
Therefore, when an early missed approach is
executed, pilots should, unless otherwise cleared by
ATC, fly the IAP as specified on the approach plate
to the missed approach point at or above the MDA orDH before executing a turning maneuver.
c.If visual reference is lost while circling −to−land
from an instrument approach, the missed approach
specified for that particular procedure must befollowed (unless an alternate missed approach
procedure is specified by ATC). To become
established on the prescribed missed approachcourse, the pilot should make an initial climbing turn
toward the landing runway and continue the turn until
established on the missed approach course. Inasmuchas the circling maneuver may be accomplished in
more than one direction, different patterns will be
required to become established on the prescribedmissed approach course, depending on the aircraft
position at the time visual reference is lost.
Adherence to the procedure will help assure that anaircraft will remain laterally within the circling and
missed approach obstruction clearance areas. Refer
to paragraph h concerning vertical obstructionclearance when starting a missed approach at other
than the MAP. (See FIG 5−4−31.)
d.At locations where ATC radar service is
provided, the pilot should conform to radar vectorswhen provided by ATC in lieu of the published
missed approach procedure. (See FIG 5−4−32.)
e.Some locations may have a preplanned alternate
missed approach procedure for use in the event theprimary NA V AID used for the missed approach
procedure is unavailable. To avoid confusion, the
alternate missed approach instructions are notpublished on the chart. However, the alternate missed
approach holding pattern will be depicted on the
instrument approach chart for pilot situational
awareness and to assist ATC by not having to issue
detailed holding instructions. The alternate missedapproach may be based on NA VAIDs not used in the
approach procedure or the primary missed approach.
When the alternate misse d approach procedure is
implemented by NOTAM, it becomes a mandatorypart of the procedure. The NOTAM will specify both
the textual instructions and any additional equipment
requirements necessary to complete the procedure.
Air traffic may also issue instructions for the alternate
missed approach when necessary, such as when theprimary missed approach NA V AID fails during the
approach. Pilots may reject an ATC clearance for an
alternate missed approach that requires equipmentnot necessary for the published approach procedure
when the alternate missed approach is issued after
beginning the approach. However, when the alternate
missed approach is issued prior to beginning the
approach the pilot must either accept the entire
procedure (including the alternate missed approach),
request a dif ferent approach procedure, or coordinate
with ATC for alternative action to be taken, i.e.,
proceed to an alternate airport, etc.
f.When approach has been missed, request
clearance for specific action; i.e., to alternative
airport, another approach, etc.
g.Pilots must ensure that they have climbed to a
safe altitude prior to proceeding off the publishedmissed approach, especially in nonradar environ-
ments. Abandoning the missed approach prior to
reaching the published altitude may not provideadequate terrain clearance. Additional climb may be
required after reaching the holding pattern before
proceeding back to the IAF or to an alternate.
h.A clearance for an instrument approach
procedure includes a clearance to fly the published
missed approach procedure, unless otherwise instruc-
ted by ATC. The published missed approachprocedure provides obstacle clearance only when the
missed approach is conducted on the missed
approach segment from or above the missed approach
point, and assumes a climb rate of 200 feet/NM or
higher, as published. If the aircraft initiates a missed
approach at a point other than the missed approach
point (see paragraph 5
−4−5b), from below MDA or
DA (H), or on a circling approach, obstacle clearanceis not necessarily provided by following the
published missed approach procedure, nor is
separation assured from other air traffic in thevicinity.
AIM 10/12/17
5−4−58 Arrival ProceduresFIG 5−4−31
Circling and Missed Approach Obstruction
Clearance Areas
X
XCLIMBING TURN
CLIMBING TURNDECISION TO MISS
HERE
DECISION
TO MISS HERE
VORVORCIRCLING
MANEUVER
(WHEN
CLEARED INRIGHT HANDTRAFFICPATTERN)
FIG 5−4−32
Missed Approach
xCHANUTE
109.2 CNU090°14501265
Portion of a Published Procedure
Remain within
10 NMVOR
MISSED APPROACH
Climbing right turn to2600 direct to VOR
2600236°
056°
5.7 NMR236056°
011°191°In the event a balked (rejected) landing occurs at a po-
sition other than the published missed approach
point, the pilot should contact ATC as soon as pos-
sible to obtain an amended clearance. If unable to
contact ATC for any reason, the pilot should attemptto re−intercept a published segment of the missed ap-
proach and comply with route and altitude
instructions. If unable to contact ATC, and in the pi-lot’s judgment it is no longer appropriate to fly the
published missed approach procedure, then consider
either maintaining visual conditions if practicableand reattempt a landing, or a circle −climb over the
airport. Should a missed approach become necessary
when operating to an airport that is not served by anoperating control tower, continuous contact with an
air traffic facility may not be possible. In this case, the
pilot should execute the appropriate go −around/
missed approach procedure without delay and contact
ATC when able to do so.
Prior to initiating an instrument approach procedure,
the pilot should assess the actions to be taken in the
event of a balked (rejected) landing beyond the
missed approach point or below the MDA or DA (H)
considering the anticipated weather conditions and
available aircraft performance. 14 CFR 91.175(e)
authorizes the pilot to fly an appropriate missedapproach procedure that ensures obstruction clear-
ance, but it does not necessarily consider separation
from other air traffic. The pilot must consider otherfactors such as the aircraft’s geographical location
with respect to the prescribed missed approach point,
direction of flight, and/or minimum turning altitudes
in the prescribed missed approach procedure. The
pilot must also consider aircraft performance, visual
climb restrictions, charted obstacles, publishedobstacle departure procedure, takeoff visual climb
requirements as expressed by nonstandard takeoff
minima, other traffic expected to be in the vicinity, or
other factors not specifically expressed by the ap-
proach procedures.
5−4−22. Use of Enhanced Flight Vision
Systems (EFVS) on Instrument Approaches
a. Introduction. An EFVS uses a head −up display
(HUD), or an equivalent display that is a head −up
presentation, to combine flight information, flight
symbology, navigation guidance, and a real −time
image of the external scene to the pilot on one display.
Imaging sensors, which may be based on forward −
looking infrared (FLIR), millimeter wave
AIM 10/12/17
5−4−59 Arrival Proceduresradiometry, millimeter wave radar, low −level light
intensification, or other real −time imaging technolo-
gies produce a real −time image of the outside scene.
During an instrument approach, an EFVS can enable
a pilot to see the approach lights, visual references
associated with the runway environment, and other
objects or features that might not be visible using
natural vision alone. Combining the flight informa-
tion, navigation guidance, and sensor imagery on a
HUD (or equivalent display) allows the pilot to
continue looking forward along the flightpath
throughout the entire approach, landing, and rollout.
An EFVS operation is an operation in which visibility
conditions require an EFVS to be used in lieu of natu-
ral vision to perform an approach or landing,
determine enhanced flight visibility, identify required
visual references, or conduct a rollout. There are two
types of EFVS operations:1.EFVS operations to touchdown and rollout.
2.EFVS operations to 100 feet above the
touchdown zone elevation (TDZE).
b. EFVS Operations to Touchdown and Roll-
out. An EFVS operation to touchdown and rollout is
an operation in which the pilot uses the enhanced
vision imagery provided by an EFVS in lieu of natural
vision to descend below DA or DH to touchdown and
rollout. (See FIG 5−4−33.) These operations may be
conducted only on Standard Instrument Approach
Procedures (SIAP) or special IAPs that have a DA or
DH (for example, precision or APV approach). An
EFVS operation to touchdown and rollout may not be
conducted on an approach that has circling
minimums. The regulations for EFVS operations
to touchdown and rollout can be found in
14 CFR § 91.176(a).
FIG 5−4−33
EFVS Operation to Touchdown and Rollout
[Photo provided by Google Earth]
AIM 10/12/17
5−4−60 Arrival Proceduresc. EFVS Operations to 100 Feet Above the
TDZE. An EFVS operation to 100 feet above the
TDZE is an operation in which the pilot uses the
enhanced vision imagery provided by an EFVS in
lieu of natural vision to descend below DA/DH or
MDA down to 100 feet above the TDZE. (See
FIG 5−4−34.) Natural vision must be used to descend
below 100 feet above the TDZE to touchdown. Theseoperations may be conducted on SIAPs or special
IAPs that have a DA/DH or MDA. An EFVS
operation to 100 feet above the TDZE may not be
conducted on an approach that has circling
minimums. The regulations for EFVS operations to
100 feet above the TDZE can be found in
14 CFR § 91.176(b).
FIG 5−4−34
EFVS Operation to 100 ft Above the TDZE
[Photo provided by Google Earth]
d. EFVS Equipment Requirements. An EFVS
that is installed on a U.S. −registered aircraft and is
used to conduct EFVS operations must conform to an
FAA−type design approval (i.e., a type certificate
(TC), amended TC, or supplemental type certificate
(STC)). A foreign−registered aircraft used to conduct
EFVS operations that does not have an FAA −type
design approval must be equipped with an EFVS that
has been approved by either the State of the Operator
or the State of Registry to meet the requirements of
ICAO Annex 6. Equipment requirements for an
EFVS operation to touchdown and rollout can be
found in 14 CFR § 91.176(a)(1), and the equipment
requirements for an EFVS operation to
100 feet above the TDZE can be found in
14 CFR § 91.176(b)(1). An operator can determine
the eligibility of their aircraft to conduct EFVSoperations by referring to the Airplane Flight
Manual, Airplane Flight Manual Supplement,
Rotorcraft Flight Manual, or Rotorcraft Flight
Manual Supplement as applicable.
e. Operating Requirements. Any operator who
conducts EFVS operations to touchdown and rollout
must have an OpSpec, MSpec, or LOA that
specifically authorizes those operations. An opera-
tor’s authorization to conduct EFVS operations to
touchdown and rollout specifies a visibility minimum
for the operation. Parts 91K, 121, 125, 129, and 135
operators who conduct EFVS operations to 100 feet
above the TDZE must have an OpSpec, MSpec, or
LOA that specifically authorizes the operation.
Part 91 operators (other than 91K operators) are not
required to have an LOA to conduct EFVS operations
AIM 10/12/17
5−4−61 Arrival Proceduresto 100 feet in the United States. Any operator
conducting an EFVS operation during an authorized
Category II or III operation must have an OpSpec,
MSpec, or LOA authorizing EFVS operations during
Category II or Category III operations.
f.Currently, EFVS operations in rotorcraft can
only be conducted on IAPs that are flown to a runway.
Instrument approach criteria, procedures, and
appropriate visual references have not yet been
developed for straight −in landing operations below
DA/DH or MDA under IFR to heliports or platforms.
An EFVS cannot be used in lieu of natural vision to
descend below published minimums on copter
approaches to a point in space (PinS) followed by a
“proceed visual flight rules (VFR)” visual segment,
or on approaches designed to a specific landing site
using a “proceed visually” visual segment.
g.A pilot who conducts EFVS operations must
receive ground and flight training specific to the
EFVS operation to be conducted. The training must
be obtained from an authorized training provider
under a training program approved by the FAA.
Additionally, recent flight experience and proficien-
cy or competency check requirements apply to EFVS
operations. These requirements are addressed in
14 CFR §§ 61.66, 91.1065, 121.441, Appendix F to
Part 121, 125.287, and 135.293.
h. Enhanced Flight Visibility and Visual
Reference Requirements. To descend below
DA/DH or MDA during EFVS operations under
14 CFR § 91.176(a) or (b), a pilot must make a
determination that the enhanced flight visibility
observed by using an EFVS is not less than what is
prescribed by the IAP being flown. In addition, the
visual references required in 14 CFR § 91.176(a) or
(b) must be distinctly visible and identifiable to the
pilot using the EFVS. The determination of enhanced
flight visibility is a separate action from that of
identifying required visual references, and is
different from ground −reported visibility. Even
though the reported visibility or the visibility
observed using natural vision may be less, as long as
the EFVS provides the required enhanced flight
visibility and a pilot meets all of the other
requirements, the pilot can continue descending
below DA/DH or MDA using the EFVS. Suitable
enhanced flight visibility is necessary to ensure the
aircraft is in a position to continue the approach and
land. It is important to understand that using an EFVSdoes not result in obtaining lower minima with
respect to the visibility or the DA/DH or MDA
specified in the IAP. An EFVS simply provides
another means of operating in the visual segment of
an IAP. The DA/DH or MDA and the visibility value
specified in the IAP to be flown do not change.
i. Flight Planning and Beginning or Continuing
an Approach Under IFR. 14 CFR Parts 121, 125,
and 135 prohibit dispatching a flight, releasing a
flight, taking off under IFR, or beginning or
continuing an approach when weather conditions are
less than the authorized minimums. A Part 121, 125,
or 135 operator’s OpSpec or LOA for EFVS
operations authorizes a visibility for dispatching or
releasing a flight and for beginning or continuing an
approach. These operational minimums are based on
the demonstrated performance of the EFVS. Once a
pilot reaches DA/DH or MDA, the pilot conducts the
EFVS operation in accordance with
14 CFR § 91.176(a) or (b) and their authorization to
conduct EFVS operations.
j. Missed Approach Considerations. A missed
approach after passing the DA/DH, or beyond the
missed approach point (MAP), involves additional
risk until established on the published missed
approach segment. Initiating a go −around after
passing the published MAP may result in loss of
obstacle clearance. As with any approach, pilot
planning should include contingencies between the
published MAP and touchdown with reference to
obstacle clearance, aircraft performance, and alter-
nate escape plans.
k. Light Emitting Diode (LED) Airport Light-
ing Impact on EFVS Operations. Incandescent
lamps have been replaced with LEDs at some airports
in threshold lights, taxiway edge lights, taxiway
centerline lights, low intensity runway edge lights,
windcone lights, beacons, and some obstruction
lighting. Additionally, there are plans to replace
incandescent lamps with LEDs in approach lighting
systems. Pilots should be aware that LED lights
cannot be sensed by infrared −based EFVSs. Further,
the FAA does not currently collect or disseminate
information about where LED lighting is installed.
l. Other Vision Systems. An Enhanced Vision
System (EVS) does not meet the requirements of an
EFVS. An EVS may present the sensor image on a
head−down display and may not be able to present the
image and flight symbology in the same scale and
alignment as the outside view. An EVS can also use
AIM 10/12/17
5−4−62 Arrival Proceduresa HUD as its display element, yet still not meet the
regulatory requirements for an EFVS. While an EVS
that uses a head −down display or HUD may provide
situation awareness to the pilot, it does not meet the
operating requirements for an EFVS. Consequently,
a pilot cannot use an EVS in lieu of natural vision to
descend below DA/DH or MDA. Unlike an EFVS, a
Synthetic Vision System (SVS) or Synthetic Vision
Guidance System (SVGS) does not provide a
real− time sensor image of the outside scene and also
does not meet the equipment requirements for EFVS
operations. A pilot cannot use a synthetic vision
image on a head −up or a head−down display in lieu
of natural vision to descend below DA/DH or MDA.
An EFVS can, however, be integrated with an SVS,
also known as a Combined Vision System (CVS). A
CVS can be used to conduct EFVS operations if all of
the requirements for an EFVS are satisfied and the
SVS image does not interfere with the pilot’s ability
to see the external scene, to identify the required
visual references, or to see the sensor image.
m. Additional Information. Operational criteria
for EFVS can be found in Advisory Circular (AC)
90−106, Enhanced Flight Vision Systems, and
airworthiness criteria for EFVS can be found in
AC 20−167, Airworthiness Approval of Enhanced
Vision System, Synthetic Vision System, Combined
Vision System, and Enhanced Flight Vision System
Equipment.
5−4−23. Visual Approach
a.A visual approach is conducted on an IFR flight
plan and authorizes a pilot to proceed visually and
clear of clouds to the airport. The pilot must have
either the airport or the preceding identified aircraft
in sight. This approach must be authorized andcontrolled by the appropriate air traffic control
facility. Reported weather at the airport must have a
ceiling at or above 1,000 feet and visibility 3 miles or
greater. A TC may authorize this type approach when
it will be operationally beneficial. Visual approachesare an IFR procedure conducted under IFR in visual
meteorological conditions. Cloud clearance require-
ments of 14 CFR Section 91.155 are not applicable,unless required by operation specifications.
b. Operating to an Airport Without Weather
Reporting Service. ATC will advise the pilot when
weather is not available at the destination airport.ATC may initiate a visual approach provided there isa reasonable assurance that weather at the airport is a
ceiling at or above 1,000 feet and visibility 3 miles or
greater (e.g., area weather reports, PIREPs, etc.).
c. Operating to an Airport With an Operating
Control Tower. Aircraft may be authorized to
conduct a visual approach to one runway while other
aircraft are conducting IFR or VFR approaches to
another parallel, intersecting, or converging runway.When operating to airports with parallel runways
separated by less than 2,500 feet, the succeeding
aircraft must report sighting the preceding aircraftunless standard separation is being provided by ATC.
When operating to parallel runways separated by atleast 2,500 feet but less than 4,300 feet, controllerswill clear/vector aircraft to the final at an angle not
greater than 30 degrees unless radar, vertical, or
visual separation is provided during the turn −on. The
purpose of the 30 degree intercept angle is to reduce
the potential for overshoots of the final and to
preclude side−by−side operations with one or both
aircraft in a belly −up configuration during the
turn−on. Once the aircraft are established within
30 degrees of final, or on the final, these operationsmay be conducted simultaneously. When the parallel
runways are separated by 4,300 feet or more, or
intersecting/converging runways are in use, ATC
may authorize a visual approach after advising all
aircraft involved that other aircraft are conductingoperations to the other runway. This may be
accomplished through use of the ATIS.
d. Separation Responsibilities. If the pilot has
the airport in sight but cannot see the aircraft to befollowed, ATC may clear the aircraft for a visual
approach; however, A TC retains both separation and
wake vortex separation responsibility. When visually
following a preceding aircraft, acceptance of thevisual approach clearance constitutes acceptance ofpilot responsibility for maintaining a safe approach
interval and adequate wake turbulence separation.
e.A visual approach is not an IAP and therefore
has no missed approach segment. If a go around isnecessary for any reason, aircraft operating at
controlled airports will be issued an appropriateadvisory/clearance/instruction by the tower. At
uncontrolled airports, aircraft are expected to remain
clear of clouds and complete a landing as soon as
possible. If a landing cannot be accomplished, the
aircraft is expected to remain clear of clouds and
contact A TC as soon as possible for further clearance.
AIM 10/12/17
5−4−63 Arrival ProceduresSeparation from other IFR aircraft will be maintained
under these circumstances.
f.Visual approaches reduce pilot/controller work-
load and expedite traffic by shortening flight paths to
the airport. It is the pilot’s responsibility to advise
ATC as soon as possible if a visual approach is notdesired.
g.Authorization to conduct a visual approach is an
IFR authorization and does not alter IFR flight plan
cancellation responsibility.
REFERENCE −
AIM Paragraph 5 −1−15 , Canceling IFR Flight Plan
h.Radar service is automatically terminated,
without advising the pilot, when the aircraft isinstructed to change to advisory frequency.
5−4−24. Charted Visual Flight Procedure
(CVFP)
a.CVFPs are charted visual approaches estab-
lished for environmental/noise considerations,and/or when necessary for the safety and ef ficiency of
air traffic operations. The approach charts depict
prominent landmarks, courses, and recommendedaltitudes to specific runways. CVFPs are designed to
be used primarily for turbojet aircraft.
b.These procedures will be used only at airports
with an operating control tower.
c.Most approach charts will depict some
NA V AID information which is for supplemental
navigational guidance only.
d.Unless indicating a Class B airspace floor, all
depicted altitudes are for noise abatement purposesand are recommended only. Pilots are not prohibited
from flying other than recommended altitudes if
operational requirements dictate.
e.When landmarks used for navigation are not
visible at night, the approach will be annotated
“PROCEDURE NOT AUTHORIZED AT NIGHT .”
f.CVFPs usually begin within 20 flying miles
from the airport.
g.Published weather minimums for CVFPs are
based on minimum vectoring altitudes rather than the
recommended altitudes depicted on charts.
h.CVFPs are not instrument approaches and do
not have missed approach segments.i.ATC will not issue clearances for CVFPs when
the weather is less than the published minimum.
j.ATC will clear aircraft for a CVFP after the pilot
reports siting a charted landmark or a preceding
aircraft. If instructed to follow a preceding aircraft,
pilots are responsible for maintaining a safe approach
interval and wake turbulence separation.
k.Pilots should advise ATC if at any point they are
unable to continue an approach or lose sight of a
preceding aircraft. Missed approaches will be
handled as a go −around.
5−4−25. Contact Approach
a.Pilots operating in accordance with an IFR
flight plan, provided they are clear of clouds and have
at least 1 mile flight visibility and can reasonablyexpect to continue to the destination airport in those
conditions, may request ATC authorization for a
contact approach.
b.Controllers may authorize a contact approach
provided:
1.The contact approach is specifically re-
quested by the pilot. ATC cannot initiate thisapproach.
EXAMPLE −
Request contact approach.
2.The reported ground visibility at the
destination airport is at least 1 statute mile.
3.The contact approach will be made to an
airport having a standard or special instrument
approach procedure.
4.Approved separation is applied between
aircraft so cleared and be tween these aircraft and
other IFR or special VFR aircraft.
EXAMPLE −
Cleared contact approach (and, if required) at or below(altitude) (r outing) if not possible (alternative pr ocedures)
and advise.
c.A contact approach is an approach procedure
that may be used by a pilot (with prior authorization
from A TC) in lieu of conducting a standard or special
IAP to an airport. It is not intended for use by a pilot
on an IFR flight clearance to operate to an airport not
having a published and functioning IAP. Nor is itintended for an aircraft to conduct an instrument
approach to one airport and then, when “in the clear,”
discontinue that approach and proceed to another
AIM 10/12/17
5−4−64 Arrival Proceduresairport. In the execution of a contact approach, the
pilot assumes the responsibility for obstruction
clearance. If radar service is being received, it will
automatically terminate when the pilot is instructed to
change to advisory frequency.
5−4−26. Landing Priority
A clearance for a specific type of approach (ILS,
RNA V , GLS, ADF, VOR or Visual Approach) to an
aircraft operating on an IFR flight plan does not mean
that landing priority will be given over other traffic.ATCTs handle all aircraft, regardless of the type of
flight plan, on a “first −come, first −served” basis.
Therefore, because of local traffic or runway in use,it may be necessary for the controller in the interest
of safety, to provide a different landing sequence. In
any case, a landing sequence will be issued to eachaircraft as soon as possible to enable the pilot to
properly adjust the aircraft’s flight path.
5−4−27. Overhead Approach Maneuver
a.Pilots operating in accordance with an
IFR flight plan in Visual Meteorological Condi-tions (VMC) may request ATC authorization for an
overhead ma neuver. An overhead maneuver is not an
instrument approach procedure. Overhead maneuver
patterns are developed at airports where aircraft have
an operational need to conduct the maneuver. Anaircraft conducting an overhead maneuver is
considered to be VFR and the IFR flight plan iscancelled w hen the aircraft reaches the initial point on
the initial approach portion of the maneuver. (See
FIG 5−4−35.) The existence of a standard overhead
maneuver pattern does not eliminate the possible
requirement for an aircraft to conform to convention-
al rectangular patterns if an overhead maneuver
cannot be approved. Aircraft operating to an airport
without a functioning control tower must initiatecancellation of an IFR flight plan prior to executing
the overhead maneuver. Cancellation of the IFR
flight plan must be accomplished after crossing thelanding threshold on the initial portion of the
maneuver or after landing. Controllers may authorize
an overhead maneuver and issue the following toarriving aircraft:
1.Pattern altitude and direction of traffic. This
information may be omitted if either is standard.
PHRASEOLOGY −
P ATTERN ALTITUDE (altitude). RIGHT TURNS.
2.Request for a report on initial approach.
PHRASEOLOGY −
REPORT INITIAL.
3.“Break” information and a request for the
pilot to report. The “Break Point” will be specified if
nonstandard. Pilots may be requested to report
“break” if required for traffic or other reasons.
PHRASEOLOGY −
BREAK AT (specified point).REPORT BREAK.
FIG 5−4−35
Overhead Maneuver
3 - 5 NM
X X
INITIAL POINTINITIAL POINTINITIAL APPROACHINITIAL APPROACH
XROLL OUTROLL OUTBREAK POINTBREAK POINT
180° TURN180° TURN
AIM 10/12/17
5−5−1 Pilot/Controller Roles and ResponsibilitiesSection 5. Pilot/Controller Roles and Responsibilities
5−5−1. General
a.The roles and responsibilities of the pilot and
controller for effective participation in the ATC
system are contained in several documents. Pilot
responsibilities are in the CFRs and the air trafficcontrollers’ are in the FAA Order JO 7110.65,
Air Traffic Control, and supplemental FAA direc-
tives. Additional and supplemental information for
pilots can be found in the current Aeronautical
Information Manual (AIM), Notices to Airmen,Advisory Circulars and aeronautical charts. Since
there are many other excellent publications produced
by nongovernment organizations, as well as othergovernment organizations, with various updating
cycles, questions concerning the latest or most
current material can be resolved by cross-checkingwith the above mentioned documents.
b.The pilot−in−command of an aircraft is directly
responsible for, and is the final authority as to the safe
operation of that aircraft. In an emergency requiring
immediate action, the pilot −in−command may
deviate from any rule in the General Subpart A and
Flight Rules Subpart B in accordance with 14 CFR
Section 91.3.
c.The air traffic controller is responsible to give
first priority to the separation of aircraft and to the
issuance of radar safety alerts, second priority to other
services that are required, but do not involveseparation of aircraft and third priority to additional
services to the extent possible.
d.In order to maintain a safe and efficient air
traffic system, it is necessary that each party fulfill
their responsibilities to the fullest.
e.The responsibilities of the pilot and the
controller intentionally overlap in many areasproviding a degree of redundancy. Should one or the
other fail in any manner, this overlapping responsi-
bility is expected to compensate, in many cases, forfailures that may affect safety.
f.The following, while not intended to be all
inclusive, is a brief listing of pilot and controller
responsibilities for some commonly used proceduresor phases of flight. More detailed explanations are
contained in other portions of this publication, the
appropriate CFRs, ACs and similar publications. The
information provided is an overview of the principles
involved and is not meant as an interpretation of therules nor is it intended to extend or diminish
responsibilities.
5−5−2. Air Traffic Clearance
a. Pilot.
1.Acknowledges receipt and understanding of
an ATC clearance.
2.Reads back any hold short of runway
instructions issued by ATC.
3.Requests clarification or amendment, as
appropriate, any time a clearance is not fully
understood or considered unacceptable from a safety
standpoint.
4.Promptly complies with an air traffic
clearance upon receipt except as necessary to cope
with an emer gency. Advises ATC as soon as possible
and obtains an amended cl earance, if deviation is
necessary.
NOTE−
A clearance to land means that appropriate separation onthe landing runway will be ensured. A landing clearance
does not relieve the pilot from compliance with any
previously issued altitude crossing restriction.
b. Controller.
1.Issues appropriate clearances for the opera-
tion to be conducted, or being conducted, in
accordance with established criteria.
2.Assigns altitudes in IFR clearances that are at
or above the minimum IFR altitudes in controlled
airspace.
3.Ensures acknowledgement by the pilot for
issued information, clearances, or instructions.
4.Ensures that readbacks by the pilot of
altitude, heading, or other items are correct. If
incorrect, distorted, or incomplete, makes corrections
as appropriate.
AIM 10/12/17
5−5−2 Pilot/Controller Roles and Responsibilities5−5−3. Contact Approach
a. Pilot.
1.Must request a contact approach and makes it
in lieu of a standard or special instrument approach.
2.By requesting the contact approach, indicates
that the flight is operating clear of clouds, has at least
one mile flight visibility, and reasonably expects to
continue to the destination airport in those conditions.
3.Assumes responsibility for obstruction clear-
ance while conducting a contact approach.
4.Advises ATC immediately if unable to
continue the contact approach or if encounters lessthan 1 mile flight visibility.
5.Is aware that if radar service is being received,
it may be automatically terminated when told to
contact the tower.
REFERENCE −
Pilot/Controller Glossary Term − Radar Service Terminated.
b. Controller.
1.Issues clearance for a contact approach only
when requested by the pilot. Does not solicit the use
of this procedure.
2.Before issuing the clearance, ascertains that
reported ground visibility at destination airport is at
least 1 mile.
3.Provides approved separation between the
aircraft cleared for a contact approach and other IFR
or special VFR aircraft. When using verticalseparation, does not assign a fixed altitude, but clears
the aircraft at or below an altitude which is at least
1,000 feet below any IFR traffic but not belowMinimum Safe Altitudes prescribed in 14 CFR
Section 91.119.
4.Issues alternative instructions if, in their
judgment, weather conditions may make completion
of the approach impracticable.
5−5−4. Instrument Approach
a. Pilot.
1.Be aware that the controller issues clearance
for approach based only on known traffic.
2.Follows the procedure as shown on the IAP,
including all restrictive notations, such as:
(a)Procedure not authorized at night;(b)Approach not authorized when local area
altimeter not available;
(c)Procedure not authorized when control
tower not in operation;
(d)Procedure not authorized when glide
slope not used;
(e)Straight-in minimums not authorized at
night; etc.
(f)Radar required; or
(g)The circling minimums published on the
instrument approach chart provide adequate obstruc-
tion clearance and pilots should not descend belowthe circling altitude until the aircraft is in a position
to make final descent for landing. Sound judgment
and knowledge of the pilot’s and the aircraft’scapabilities are the criteria for determining the exact
maneuver in each instance since airport design and
the aircraft position, altitude and airspeed must all be
considered.
REFERENCE −
AIM, Paragraph 5 −4−20 , Approach and Landing Minimums
3.Upon receipt of an approach clearance while
on an unpublished route or being radar vectored:
(a)Complies with the minimum altitude for
IFR; and
(b)Maintains the last assigned altitude until
established on a segment of a published route or IAP,
at which time published altitudes apply.
4.When applicable, apply cold temperature
correction to instrument approach segments. Advise
ATC when intending to apply cold temperature
correction and of the amount of correction requiredfor each affected segment on initial contact (or as
soon as possible). This information is required for
ATC to provide aircraft appropriate vertical separa-
tion between known traffic.
REFERENCE −
AIM, Paragraph 7 −2−3 , Altimeter Errors
AIM, TBL 7 −2−3, ICAO Cold Temperature Error
b. Controller.
1.Issues an approach clearance based on known
traffic.
2.Issues an IFR approach clearance only after
the aircraft is established on a segment of published
route or IAP , or assigns an appropriate altitude for the
aircraft to maintain until so established.
AIM 10/12/17
5−5−3 Pilot/Controller Roles and Responsibilities5−5−5. Missed Approach
a. Pilot.
1.Executes a missed approach when one of the
following conditions exist:
(a)Arrival at the Missed Approach
Point (MAP) or the Decision Height (DH) and visual
reference to the runway environment is insuf ficient to
complete the landing.
(b)Determines that a safe approach or
landing is not possible (see subparagraph 5 −4−21h).
(c)Instructed to do so by ATC.
2.Advises ATC that a missed approach will be
made. Include the reason for the missed approachunless the missed approach is initiated by ATC.
3.Complies with the missed approach instruc-
tions for the IAP being executed from the MAP,
unless other missed approach instructions arespecified by ATC.
4.If executing a missed approach prior to
reaching the MAP, fly the lateral navigation path of
the instrument procedure to the MAP. Climb to thealtitude specified in the missed approach procedure,
except when a maximum altitude is specified
between the final approach fix (FAF) and the MAP. In
that case, comply with the maximum altitude
restriction. Note, this may require a continueddescent on the final approach.
5.When applicable, apply cold temperature
correction to the published missed approach segment.
Advise ATC when intending to apply coldtemperature correction and of the amount of
correction required on initial contact (or as soon as
possible). This information is required for ATC toprovide aircraft appropriate vertical separation
between known traffic. The pilot must not apply an
altitude correction to an assigned altitude whenprovided an initial heading to fly or radar vector in
lieu of published missed approach procedures, unless
approved by ATC.
REFERENCE −
AIM, Paragraph 7 −2−3 , Altimeter Errors
AIM, TBL 7 −2−3, ICAO Cold Temperature Error
6.Following a missed approach, requests
clearance for specific action; i.e., another approach,
hold for improved conditions, proceed to an alternate
airport, etc.b. Controller.
1.Issues an approved alternate missed approach
procedure if it is desired that the pilot execute aprocedure other than as depicted on the instrument
approach chart.
2.May vector a radar identified aircraft
executing a missed approach when operationallyadvantageous to the pilot or the controller.
3.In response to the pilot’s stated intentions,
issues a clearance to an alternate airport, to a holding
fix, or for reentry into the approach sequence, as
traffic conditions permit.
5−5−6. Radar Vectors
a. Pilot.
1.Promptly complies with headings and
altitudes assigned to you by the controller.
2.Questions any assigned heading or altitude
believed to be incorrect.
3.If operating VFR and compliance with any
radar vector or altitude would cause a violation of any
CFR, advises ATC and obtains a revised clearance or
instructions.
b. Controller.
1.Vectors aircraft in Class A, Class B, Class C,
Class D, and Class E airspace:
(a)For separation.
(b)For noise abatement.
(c)To obtain an operational advantage for the
pilot or controller.
2.Vectors aircraft in Class A, Class B, Class C,
Class D, Class E, and Class G airspace when
requested by the pilot.
3.Vectors IFR aircraft at or above minimum
vectoring altitudes.
4.May vector VFR aircraft, not at an ATC
assigned altitude, at any altitude. In these cases,
terrain separation is the pilot’s responsibility.
5−5−7. Safety Alert
a. Pilot.
1.Initiates appropriate action if a safety alert is
received from ATC.
AIM 10/12/17
5−5−4 Pilot/Controller Roles and Responsibilities2.Be aware that this service is not always
available and that many factors affect the ability of
the controller to be aware of a situation in which
unsafe proximity to terrain, obstructions, or another
aircraft may be developing.
b. Controller.
1.Issues a safety alert if aware an aircraft under
their control is at an altitude which, in the controller’s
judgment, places the aircraft in unsafe proximity to
terrain, obstructions or another aircraft. Types ofsafety alerts are:
(a) Terrain or Obstruction Alert. Immedi-
ately issued to an aircraft under their control if aware
the aircraft is at an altitude believed to place the
aircraft in unsafe proximity to terrain or obstructions.
(b) Aircraft Conflict Alert. Immediately
issued to an aircraft under their control if aware of an
aircraft not under their control at an altitude believed
to place the aircraft in unsafe proximity to each other.
With the alert, they offer the pilot an alternative, iffeasible.
2.Discontinue further alerts if informed by the
pilot action is being taken to correct the situation or
that the other aircraft is in sight.
5−5−8. See and Avoid
a. Pilot. When meteorological conditions permit,
regardless of type of flight plan or whether or notunder control of a radar facility, the pilot is
responsible to see and avoid other traffic, terrain, or
obstacles.
b. Controller.
1.Provides radar traffic information to radar
identified aircraft operating outside positive control
airspace on a workload permitting basis.
2.Issues safety alerts to aircraft under their
control if aware the aircraft is at an altitude believed
to place the aircraft in unsafe proximity to terrain,
obstructions, or other aircraft.
5−5−9. Speed Adjustments
a. Pilot.
1.Advises ATC any time cruising airspeed
varies plus or minus 5 percent or 10 knots, whichever
is greater, from that given in the flight plan.2.Complies with speed adjustments from ATC
unless:
(a)The minimum or maximum safe airspeed
for any particular operation is greater or less than the
requested airspeed. In such cases, advises ATC.
NOTE−
It is the pilot’ s responsibility and prerogative to refusespeed adjustments considered ex cessive or contrary to the
aircraft’ s operating specifications.
(b)Operating at or above 10,000 feet MSL on
an ATC assigned SPEED ADJUSTMENT of more
than 250 knots IAS and subsequent clearance is
received for descent below 10,000 feet MSL. In such
cases, pilots are expected to comply with 14 CFR
Section 91.117(a).
3.When complying with speed adjustment
assignments, maintains an indicated airspeed withinplus or minus 10 knots or 0.02 Mach number of the
specified speed.
b. Controller.
1.Assigns speed adjustments to aircraft when
necessary but not as a substitute for good vectoring
technique.
2.Adheres to the restrictions published in FAA
Order JO 7110.65, Air Traffic Control, as to whenspeed adjustment procedures may be applied.
3.Avoids speed adjustments requiring alternate
decreases and increases.
4.Assigns speed adjustments to a specified IAS
(KNOTS)/Mach number or to increase or decrease
speed using increments of 5 knots or multiples
thereof.
5.Terminates A TC-assigned speed adjustments
when no longer required by issuing further
instructions to pilots in the following manner:
(a)Advises pilots to “resume normal speed”
when the aircraft is on a heading, random routing,
charted procedure, or route without published speed
restrictions.
(b)Instructs pilots to “comply with speed
restrictions” when the aircraft is joining or resuming
a charted procedure or route with published speed
restrictions.
CAUTION −
The phraseology “Climb via SID” requires compliance
with all altitude and/or speed restrictions depicted on the
procedure.
AIM 10/12/17
5−5−5 Pilot/Controller Roles and Responsibilities(c)Instructs pilots to “resume published
speed” when aircraft are cleared via a charted
instrument flight procedure that contains published
speed restrictions.
(d)Advises aircraft to “delete speed restric-
tions” when ATC assigned or published speed
restrictions on a charted procedure are no longer
required.
(e)Clears pilots for approach without restat-
ing previously issued speed adjustments.
REFERENCE −
Pilot/Controller Glossary Term − Resume Normal Speed
Pilot/Controller Glossary Term − Resume Published Speed
6.Gives due consideration to aircraft capabili-
ties to reduce speed while descending.
7.Does not assign speed adjustments to aircraft
at or above FL 390 without pilot consent.
5−5−10. Traffic Advisories (Traffic
Information)
a. Pilot.
1.Acknowledges receipt of traffic advisories.
2.Informs controller if traffic in sight.
3.Advises ATC if a vector to avoid traffic is
desired.
4.Does not expect to receive radar traffic
advisories on all traffic. Some aircraft may not appear
on the radar display. Be aware that the controller may
be occupied with higher priority duties and unable to
issue traffic information for a variety of reasons.
5.Advises controller if service is not desired.
b. Controller.
1.Issues radar traffic to the maximum extent
consistent with higher priority duties except inClass A airspace.
2.Provides vectors to assist aircraft to avoid
observed traffic when requested by the pilot.
3.Issues traffic information to aircraft in the
Class B, Class C, and Class D surface areas forsequencing purposes.
4.Controllers are required to issue to each
aircraft operating on intersecting or nonintersectingconverging runways where projected flight paths
will cross.
5−5−11. Visual Approach
a. Pilot.
1.If a visual approach is not desired, advises
ATC.
2.Complies with controller’s instructions for
vectors toward the airport of intended landing or to a
visual position behind a preceding aircraft.
3.The pilot must, at all times, have either the
airport or the preceding aircraft in sight. After being
cleared for a visual approach, proceed to the airport
in a normal manner or follow the preceding aircraft.Remain clear of clouds while conducting a visual
approach.
4.If the pilot accepts a visual approach
clearance to visually follow a preceding aircraft, you
are required to establish a safe landing interval behind
the aircraft you were instructed to follow. You areresponsible for wake turbulence separation.
5.Advise A TC immediately if the pilot is unable
to continue following the preceding aircraft, cannot
remain clear of clouds, needs to climb, or loses sight
of the airport.
6.Be aware that radar service is automatically
terminated, without being advised by ATC, when the
pilot is instructed to change to advisory frequency.
7.Be aware that there may be other traffic in the
traffic pattern and the landing sequence may differ
from the traffic sequence assigned by approachcontrol or ARTCC.
b. Controller.
1.Do not clear an aircraft for a visual approach
unless reported weather at the airport is ceiling at or
above 1,000 feet and visibility is 3 miles or greater.
When weather is not available for the destinationairport, inform the pilot and do not initiate a visual
approach to that airport unless there is reasonable
assurance that descent and flight to the airport can be
made visually.
Issue visual approach clearance when the
pilot repor ts sighting either the airport or a preceding
aircraft which is to be followed.
3.Provide separation except when visual
separation is being applied by the pilot.
AIM 10/12/17
5−5−6 Pilot/Controller Roles and Responsibilities4.Continue flight following and traffic in-
formation until the aircraft has landed or has been
instructed to change to advisory frequency.
5.For all aircraft, inform the pilot when the
preceding aircraft is a heavy. Inform the pilot of a
small aircraft when the preceding aircraft is a B757.Visual separation is prohibited behind super aircraft.
6.When weather is available for the destination
airport, do not initiate a vector for a visual approach
unless the reported ceiling at the airport is 500 feet or
more above the MV A and visibility is 3 miles or more.
If vectoring weather minima are not available butweather at the airport is ceiling at or above 1,000 feet
and visibility of 3 miles or greater, visual approaches
may still be conducted.
5−5−12. Visual Separation
a. Pilot.
1.Acceptance of instructions to follow another
aircraft or to provide visual separation from it is an
acknowledgment that the pilot will maneuver theaircraft as necessary to avoid the other aircraft or to
maintain in-trail separation. Pilots are responsible to
maintain visual separation until flight paths (altitudes
and/or courses) diverge.
2.If instructed by A TC to follow another aircraft
or to provide visual separation from it, promptlynotify the controller if you lose sight of that aircraft,
are unable to maintain continued visual contact with
it, or cannot accept the responsibility for your ownseparation for any reason.
3.The pilot also accepts responsibility for wake
turbulence separation under these conditions.
b. Controller. Applies visual separation only:
1.Within the terminal area when a controller
has both aircraft in sight or by instructing a pilot who
sees the other aircraft to maintain visual separation
from it.
2.Pilots are responsible to maintain visual
separation until flight paths (altitudes and/or courses)
diverge.
3.Within en route airspace when aircraft are on
opposite courses and one pilot reports having seen the
other aircraft and that the aircraft have passed each
other.5−5−13. VFR-on-top
a. Pilot.
1.This clearance must be requested by the pilot
on an IFR flight plan, and if approved, allows the pilot
the choice (subject to any ATC restrictions) to select
an altitude or flight level in lieu of an assignedaltitude.
NOTE−
VFR−on−top is not permitted in certain airspace areas,
such as Class A airspace, certain restricted areas, etc.
Consequently, IFR flights operating VFR −on−top will
avoid such airspace.
REFERENCE −
AIM, Paragraph 4 −4−8 , IFR Clearance VFR −on−top
AIM, Paragraph 4 −4−11 , IFR Separation Standards
AIM, Paragraph 5 −3−2 , Position Reporting
AIM, Paragraph 5 −3−3 , Additional Reports
2.By requesting a VFR-on-top clearance, the
pilot assumes the sole responsibility to be vigilant so
as to see and avoid other aircraft and to:
(a)Fly at the appropriate VFR altitude as
prescribed in 14 CFR Section 91.159.
(b)Comply with the VFR visibility and
distance from clouds criteria in 14 CFR Sec-tion 91.155, Basic VFR Weather Minimums .
(c)Comply with instrument flight rules that
are applicable to this flight; i.e., minimum IFRaltitudes, position reporting, radio communications,
course to be flown, adherence to ATC clearance, etc.
3.Should advise ATC prior to any altitude
change to ensure the exchange of accurate traffic
information.
b. Controller.
1.May clear an aircraft to maintain VFR-on-top
if the pilot of an aircraft on an IFR flight plan requeststhe clearance.
2.Informs the pilot of an aircraft cleared to
climb to VFR-on-top the reported height of the topsor that no top report is available; issues an alternate
clearance if necessary; and once the aircraft reports
reaching VFR-on-top, reclears the aircraft tomaintain VFR-on-top.
3.Before issuing clearance, ascertain that the
aircraft is not in or will not enter Class A airspace.
AIM 10/12/17
5−5−7 Pilot/Controller Roles and Responsibilities5−5−14. Instrument Departures
a. Pilot.
1.Prior to departure considers the type of terrain
and other obstructions on or in the vicinity of the
departure airport.
2.Determines if obstruction avoidance can be
maintained visually or that the departure procedureshould be followed.
3.Determines whether an obstacle departure
procedure (ODP) and/or DP is available for
obstruction avoidance. One option may be a Visual
Climb Over Airport (VCOA). Pilots must adviseATC as early as possible of the intent to fly the VCOA
prior to departure.
4.At airports where IAPs have not been
published, hence no published departure procedure,
determines what action will be necessary and takessuch action that will assure a safe departure.
b. Controller.
1.At locations with airport traffic control
service, when necessary, specifies direction of
takeoff, turn, or initial heading to be flown after
takeoff, consistent with published departure proce-dures (DP) or diverse vector areas (DV A), where
applicable.
2.At locations without airport traffic control
service but within Class E surface area when
necessary to specify direction of takeoff, turn, orinitial heading to be flown, obtains pilot’s concur-
rence that the procedure will allow the pilot to comply
with local traffic patterns, terrain, and obstructionavoidance.
3.When the initial heading will take the aircraft
off an assigned procedure (for example, an RNA V
SID with a published lateral path to a waypoint and
crossing restrictions from the departure end ofrunway), the controller will assign an altitude to
maintain with the initial heading.
4.Includes established departure procedures as
part of the ATC clearance when pilot compliance is
necessary to ensure separation.5−5−15. Minimum Fuel Advisory
a. Pilot.
1.Advise ATC of your minimum fuel status
when your fuel supply has reached a state where,
upon reaching destination, you cannot accept any
undue delay.
2.Be aware this is not an emergency situation,
but merely an advisory that indicates an emergencysituation is possible should any undue delay occur.
3.On initial contact the term “minimum fuel”
should be used after stating call sign.
EXAMPLE −
Salt Lake Approach, United 621, “minimum fuel.”
4.Be aware a minimum fuel advisory does not
imply a need for traffic priority.
5.If the remaining usable fuel supply suggests
the need for traffic priority to ensure a safe landing,
you should declare an emergency due to low fuel andreport fuel remaining in minutes.
REFERENCE −
Pilot/Controller Glossary Term − Fuel Remaining.
b. Controller.
1.When an aircraft declares a state of minimum
fuel, relay this information to the facility to whomcontrol jurisdiction is transferred.
2.Be alert for any occurrence which might
delay the aircraft.
5−5−16. RNAV and RNP Operations
a. Pilot.
1.If unable to comply with the requirements of
an RNA V or RNP procedure, pilots must advise air
traffic control as soon as possible. For example,“N1234, failure of GPS system, unable RNA V ,
request amended clearance.”
2.Pilots are not authorized to fly a published
RNA V or RNP procedure (instrument approach,
departure, or arrival procedure) unless it is retrievable
by the procedure name from the current aircraftnavigation database and conforms to the charted
procedure. The system must be able to retrieve the
procedure by name from the aircraft navigationdatabase, not just as a manually entered series of
waypoints.
3.Whenever possible, RNA V routes (Q − or
T−route) should be extracted from the database in
AIM 10/12/17
5−5−8 Pilot/Controller Roles and Responsibilitiestheir entirety, rather than loading RNA V route
waypoints from the database into the flight plan
individually. However, selecting and inserting
individual, named fixes from the database is
permitted, provided all fixes along the publishedroute to be flown are inserted.
4.Pilots must not change any database
waypoint type from a fly −by to fly−over, or vice
versa. No other modification of database waypoints
or the creation of user −defined waypoints on
published RNA V or RNP procedures is permitted,except to:
(a)Change altitude and/or airspeed waypoint
constraints to comply with an ATC clearance/
instruction.
(b)Insert a waypoint along the published
route to assist in complying with ATC instruction,
example, “Descend via the WILMS arrival except
cross 30 north of BRUCE at/or below FL 210.” This
is limited only to systems that allow along −track
waypoint construction.
5.Pilots of FMS −equipped aircraft, who are
assigned an RNA V DP or STAR procedure and
subsequently receive a change of runway, transition
or procedure, must verify that the appropriate
changes are loaded and available for navigation.
6.For RNA V 1 DPs and ST ARs, pilots must use
a CDI, flight director and/or autopilot, in lateral
navigation mode. Other methods providing an
equivalent level of performance may also be
acceptable.
7.For RNA V 1 DPs and STARs, pilots of
aircraft without GPS, using DME/DME/IRU, must
ensure the aircraft navigation system position is
confirmed, within 1,000 feet, at the start point oftake−off roll. The use of an automatic or manual
runway update is an acceptable means of compliance
with this requirement. Other methods providing anequivalent level of performance may also be
acceptable.
8.For procedures or routes requiring the use of
GPS, if the navigation system does not automatically
alert the flight crew of a loss of GPS, the operatormust develop procedures to verify correct GPS
operation.
9.RNA V terminal procedures (DP and STAR)
may be amended by ATC issuing radar vectors and/or
clearances direct to a waypoint. Pilots should avoid
premature manual deletion of waypoints from their
active “legs” page to allow for rejoining procedures.
10.RAIM Prediction: If TSO −C129 equipment
is used to solely satisfy the RNA V and RNP
requirement, GPS RAIM availability must be
confirmed for the intended route of flight (route and
time). If RAIM is not available, pilots need an
approved alternate means of navigation.
REFERENCE −
AIM, Paragraph 5 −1−16 , RNAV and RNP Operations
11. Definition of “established” for RNA V and
RNP operations. An aircraft is considered to be
established on-course during RNA V and RNPoperations anytime it is within 1 times the required
accuracy for the segment being flown. For example,
while operating on a Q-Route (RNA V 2), the aircraft
is considered to be established on-course when it is
within 2 NM of the course centerline.
NOTE−
1.Pilots must be aware of how their navigation system
operates, along with any AFM limitations, and confirm
that the air craft’ s lateral deviation display (or map display
if being used as an allowed alternate means) is suitable forthe accuracy of the segment being flown. Automatic scalingand alerting changes are appropriate for some operations.For example, TSO-C129 systems change within 30 miles of
destination and within 2 miles of F AF to support appr oach
operations. For some navigation systems and operations,manual selection of scaling will be necessary.
2.Pilots flying FMS equipped aircraft with barometric
vertical navigation (Baro-VNAV) may descend when the
aircraft is established on-course following FMS leg
transition to the next segment. Leg transition normallyoccurs at the turn bisector for a fly-by waypoint (r eference
paragraph 1-2-1 for more on waypoints). When using full
automation, pilots should monitor the aircraft to ensure the
aircraft is turning at appropriate lead times anddescending once established on-course.
3.Pilots flying TSO-C129 navigation system equipped
aircraft without full automation should use normal lead
points to begin the turn. Pilots may descend whenestablished on-course on the next segment of the appr oach.
AIM 10/12/17
5−6−1 National Security and Interception ProceduresSection 6. National Security and Interception Procedures
5−6−1. National Security
National security in the control of air traffic is
governed by 14 Code of Federal Regulations (CFR)
Part 99, Security Control of Air Traffic .
5−6−2. National Security Requirements
a.Pursuant to 14 CFR 99.7, Special Security
Instructions , each person operating an aircraft in an
Air Defense Identification Zone (ADIZ) or Defense
Area must, in addition to the applicable rules of
Part 99, comply with special security instructionsissued by the FAA Administrator in the interest of
national security, pursuant to agreement between the
FAA and the Department of Defense (DOD), orbetween the FAA and a U.S. Federal security or
intelligence agency.
b.In addition to the requirements prescribed in
this section, national security requirements for
aircraft operations to or from, within, or transitingU.S. territorial airspace are in effect pursuant to
14 CFR 99.7; 49 United States Code (USC) 40103,
Sovereignty and Use of Airspace ; and 49 USC 41703,
Navigation of Foreign Civil Aircraft . Aircraft
operations to or from, within, or transiting U.S.
territorial airspace must also comply with all otherapplicable regulations published in 14 CFR.
c.Due to increased security measures in place at
many areas and in accordance with 14 CFR 91.103,
Preflight Action , prior to departure, pilots must
become familiar with all available informationconcerning that flight. Pilots are responsible to
comply with 14 CFR 91.137 ( Temporary flight
restrictions in the vicinity of disaster/hazard areas ),
91.138 ( Temporary flight restrictions in national
disaster ar eas in the State of Hawaii ), 91.141 ( Flight
restrictions in the proximity of the Presidential andother parties ), and 91.143 ( Flight limitation in the
proximity of space flight operations ) when conduct-
ing flight in an area where a temporary flightrestrictions area is in effect, and should check
appropriate NOTAMs during flight planning. In
addition, NOTAMs may be issued for NationalSecurity Areas (NSA) that temporarily prohibit flight
operations under the provisions of 14 CFR 99.7.REFERENCE −
AIM, Paragraph 3 −4−8, National Security Areas
AIM, Paragraph 3 −5−3, Temporary Flight Restrictions
d.Noncompliance with the national security
requirements for aircraft operations contained in this
section may result in denial of flight entry into U.S.
territorial airspace or ground stop of the flight at aU.S. airport.
e.Pilots of aircraft that do not adhere to the
procedures in the national security requirements foraircraft operations contained in this section may be
intercepted, and/or detained and interviewed by
federal, state, or local law enforcement or othergovernment personnel.
5−6−3. Definitions
a.Air Defense Identification Zone (ADIZ) means
an area of airspace over land or water, in which the
ready identification, location, and control of all
aircraft (except Department of Defense and lawenforcement aircraft) is required in the interest of
national security.
b.Defense Area means any airspace of the
contiguous U.S. that is not an ADIZ in which the
control of aircraft is required for reasons of national
security.
c.U.S. territorial airspace, for the purposes of this
section, means the airspace over the U.S., its
territories, and possessions, and the airspace over the
territorial sea of the U.S., which extends 12 nauticalmiles from the baselines of the U.S., determined in
accordance with international law.
d.To U.S. territorial airspace means any flight
that enters U.S. territorial airspace after departure
from a location outside of the U.S., its territories or
possessions, for landing at a destination in the U.S.,its territories or possessions.
e.From U.S. territorial airspace means any flight
that exits U.S. territorial airspace after departure from
a location in the U.S., its territories or possessions,
and lands at a destination outside the U.S., its
territories or possessions.
f.Within U.S. territorial airspace means any flight
departing from a location inside of the U.S., its
territories or possessions, whi ch operates en route to
AIM 10/12/17
5−6−2 National Security and Interception Proceduresa location inside the U.S., its territories or
possessions.
g.Transit or transiting U.S. territorial airspace
means any flight departing from a location outside of
the U.S., its territories or possessions, which operates
in U.S. territorial airspace en route to a locationoutside the U.S., its territories or possessions without
landing at a destination in the U.S., its territories or
possessions.
h.Aeronautical facility , for the purposes of this
section, means a communications facility where
flight plans or position reports are normally filed
during flight operations.
5−6−4. ADIZ Requirements
a.To facilitate early identification of all aircraft in
the vicinity of U.S. airspace boundaries, Air DefenseIdentification Zones (ADIZ) have been established.
All aircraft must meet certain requirements to
facilitate early identification when operating into,within, and across an ADIZ, as described in
14 CFR 99.
b.Requirements for aircraft operations are as
follows:
1. Transponder Requirements. Unless other-
wise authorized by ATC, each aircraft conductingoperations into, within, or across the contiguous U.S.
ADIZ must be equipped with an operable radar
beacon transponder having altitude reporting capa-bility, and that transponder must be turned on and set
to reply on the appropriate code or as assigned by
ATC. (See 14 CFR 99.13, Transponder −On Require-
ments , for additional information.)
2. Two−way Radio. In accordance with
14 CFR 99.9, Radio Requirements , any person
operating in an ADIZ must maintain two −way radio
communication with an appropriate aeronautical
facility. For two −way radio communications failure,
follow instructions contained in 14 CFR 99.9.
3. Flight Plan. In accordance with
14 CFR 99.11, Flight Plan Requirements , and
14 CFR 99.9, except as specified in subparagraph
5−6−4e, no person may operate an aircraft into,
within, or from a departure point within an ADIZ,unless the person files, activates, and closes a flight
plan with an appropriate aeronautical facility, or is
otherwise authorized by air traffic control as follows:(a)Pilots must file an Instrument Flight Rules
(IFR) flight plan or file a Defense V isual Flight Rules
(DVFR) flight plan containing the time and point of
ADIZ penetration;
(b)The pilot must activate the DVFR flight
plan with U.S. Flight Service and set the aircraft
transponder to the assigned discrete beacon code
prior to entering the ADIZ;
(c)The IFR or DVFR aircraft must depart
within 5 minutes of the estimated departure time
contained in the flight plan, except for (d) below;
(d)If the airport of departure within the
Alaskan ADIZ has no facility for filing a flight plan,
the flight plan must be filed immediately after takeoff
or when within range of an appropriate aeronauticalfacility;
(e)State ai rcraft (U.S. or foreign) planning to
operate through an ADIZ should enter ICAO Code M
in Item 8 of the flight plan to assist in identification
of the aircraft as a state aircraft.
c. Position Reporting Before Penetration of
ADIZ.
In accordance with 14 CFR 99.15, Position Reports ,
before entering the ADIZ, the pilot must report to an
appropriate aeronautical facility as follows:
1. IFR flights in contr olled airspace. The pilot
must maintain a continuous watch on the appropriate
frequency and report the time and altitude of passing
each designated reporting point or those reporting
points specified or requested by ATC, except thatwhile the aircraft is under radar control, only the
passing of those reporting points specifically
requested by ATC need be reported. (See
14 CFR 91.183(a), IFR Communications .)
2. DVFR flights and IFR flights in uncon-
trolled airspace:
(a)The time, position, and altitude at which
the aircraft passed the last reporting point before
penetration and the estimated time of arrival over the
next appropriate reporting point along the flight
route;
(b)If there is no appropriate reporting point
along the flight route, the pilot reports at least 15
minutes before penetration: the estimated time,
position, and altitude at which the pilot will penetrate;
or
(c)If the departure airport is within an ADIZ
or so close to the ADIZ boundary that it prevents the
AIM 10/12/17
5−6−3 National Security and Interception Procedurespilot from complying with (a) or (b) above, the pilot
must report immediately after departure: the time of
departure, the altitude, and the estimated time of
arrival over the first reporting point along the flight
route.
3. Foreign civil air craft. If the pilot of a foreign
civil aircraft that intends to enter the U.S. through an
ADIZ cannot comply with the reporting requirements
in subparagraphs c1 or c2 above, as applicable, thepilot must report the position of the aircraft to the
appropriate aeronautical facility not less than 1 hour
and not more than 2 hours average direct cruising
distance from the U.S.
d. Land−Based ADIZ. Land−Based ADIZ are
activated and deactivated over U.S. metropolitanareas as needed, with dimensions, activation dates
and other relevant information disseminated via
NOTAM. Pilots unable to comply with all NOTAMrequirements must remain clear of Land −Based
ADIZ. Pilots entering a Land −Based ADIZ without
authorization or who fail to follow all requirementsrisk interception by military fighter aircraft.
e. Exceptions to ADIZ requirements.
1.Except for the national security requirements
in paragraph 5 −6−2, transponder requirements in
subparagraph 5 −6−4b1, and position reporting in
subparagraph 5 −6−4c, the ADIZ requirements in
14 CFR Part 99 described in this section do not apply
to the following aircraft operations pursuant to
Section 99.1(b), Applicability:
(a)Within the 48 contiguous States or within
the State of Alaska, on a flight which remains within
10 NM of the point of departure;
(b)Operating at true airspeed of less than 180
knots in the Hawaii ADIZ or over any island, or
within 12 NM of the coastline of any island, in the
Hawaii ADIZ;
(c)Operating at true airspeed of less than 180
knots in the Alaska ADIZ while the pilot maintains a
continuous listening watch on the appropriatefrequency; or
(d)Operating at true airspeed of less than 180
knots in the Guam ADIZ.
2.An FAA air route traffic control center
(ARTCC) may exempt certain aircraft operations on
a local basis in concurrence with the DOD or pursuant
to an agreement with a U.S. Federal security orintelligence agency . (See 14 CFR 99.1 for additional
information.)
f.A VFR flight plan filed inflight makes an
aircraft subject to interception for positive identifica-
tion when entering an ADIZ. Pilots are therefore
urged to file the required DVFR flight plan either in
person or by telephone prior to departure when able.
5−6−5. Civil Aircraft Operations To or From
U.S. Territorial Airspace
a.Civil aircraft, except as described in subpara-
graph 5−
6−5b below, are authorized to operate to or
from U.S. territorial airspace if in compliance with all
of the following conditions:
1.File and are on an active flight plan (IFR,
VFR, or DVFR);
2.Are equipped with an operational transpon-
der with altitude reporting capability, andcontinuously squawk an ATC assigned transponder
code;
3.Maintain two −way radio communications
with ATC;
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph
5−6−2;
5.Comply with all applicable U.S. Customs and
Border Protection (CBP) requirements, including
Advance Passenger Information System (APIS)requirements (see subparagraph 5 −6−5c below for
CBP APIS information), in acco rdance with 19 CFR
Part 122, Air Commerce Regulations ; and
6.Are in receipt of, and are operating in
accordance with, an FAA routing authorization if the
aircraft is registered in a U.S. State Department −des-
ignated special interest country or is operating withthe ICAO three letter designator (3LD) of a company
in a country listed as a U.S. State Department −desig-
nated special interest country, unless the operatorholds valid FAA Part 129 operations specifications.
VFR and DVFR flight operations are prohibited for
any aircraft requiring an FAA routing authorization.(See paragraph 5 −6−11 for FAA routing authoriza-
tion information).
b.Civil aircraft registered in the U.S., Canada, or
Mexico with a maximum certificated takeoff gross
weight of 100,309 pounds (45,500 kgs) or less that are
AIM 10/12/17
5−6−4 National Security and Interception Proceduresoperating without an operational transponder, and/or
the ability to maintain two −way radio communica-
tions with ATC, are authorized to operate to or from
U.S. territorial airspace over Alaska if in compliance
with all of the following conditions:
1.Depart and land at an airport within the U.S.
or Canada;
2.Enter or exit U.S. territorial airspace over
Alaska north of the fifty −fourth parallel;
3.File and are on an active flight plan;
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph5−6−2;
5.Squawk 1200 if VFR and equipped with a
transponder; and
6.Comply with all applicable U.S. CBP
requirements, including Advance Passenger Infor-
mation System (APIS) requirements (see
subparagraph 5 −6−5c below for CBP APIS informa-
tion), in accordance with 19 CFR Part 122, Air
Commerce Regulations .
c. CBP APIS Information. Information about
U.S. CBP APIS requirements is available athttp://www.cbp.gov.
5−6−6. Civil Aircraft Operations Within U.S.
Territorial Airspace
a.Civil aircraft with a maximum certificated
takeoff gross weight less than or equal to 100,309
pounds (45,500 kgs) are authorized to operate within
U.S. territorial airspace in accordance with allapplicable regulations and VFR in airport traffic
pattern areas of U.S. airports near the U.S. border,
except for those described in subparagraph 5 −6−6b
below.
b.Civil aircraft with a maximum certificated
takeoff gross weight less than or equal to 100,309
pounds (45,500 kgs) and registered in a U.S. State
Department −designated special interest country or
operating with the ICAO 3LD of a company in a
country listed as a U.S. State Department −designated
special interest country, unless the operator holdsvalid FAA Part 129 operations specifications, must
operate within U.S. territorial airspace in accordance
with the same requirements as civil aircraft with amaximum certificated takeoff gross weight greater
than 100,309 pounds (45,500 kgs), as described in
subparagraph 5 −6−6c below.
c.Civil aircraft with a maximum certificated
takeoff gross weight greater than 100,309 pounds
(45,500 kgs) are authorized to operate within U.S.
territorial airspace if in compliance with all of the
following conditions:
File and are on an active flight plan (IFR or
VFR);
2.Equipped with an operational transponder
with altitude reporting capability, and continuouslysquawk an ATC assigned transponder code;
3.Maintain two −way radio communications
with ATC;
4.Aircraft not registered in the U.S. must
operate under an approved Transportation Security
Administration (TSA) aviation security program (see
paragraph 5 −6−10 for TSA aviation security program
information) or in accordance with an FAA/TSA
airspace waiver (see paragraph 5 −6−9 for F AA/TSA
airspace waiver information), except as authorized in
5−6−6c6. below;
5.Are in receipt of, and are operating in
accordance with an FAA routing authorization and an
FAA/TSA airspace waiver if the aircraft is registered
in a U.S. State Department −designated special
interest country or is operating with the ICAO 3LD of
a company in a country listed as a U.S. StateDepartment −designated special interest country,
unless the operator holds valid FAA Part 129
operations specifications. VFR and DVFR flightoperations are prohibited for any aircraft requiring an
FAA routing authorization. (See paragraph 5 −6−11
for FAA routing authorization information.); and
6.Aircraft not registered in the U.S., when
conducting post −maintenance, manufacturer, pro-
duction, or acceptance flight test operations, areexempt from the requirements in 5 −6−6c4 above if all
of the following requirements are met:
(a)A U.S. company must have operational
control of the aircraft;
(b)An FAA−certificated pilot must serve as
pilot in command;
(c)Only crewmembers are permitted onboard
the aircraft; and
(d)“Maintenance Flight” is included in the
remarks section of the flight plan.
AIM 10/12/17
5−6−5 National Security and Interception Procedures5−6−7. Civil Aircraft Operations Transiting
U.S. Territorial Airspace
a.Civil aircraft (except those operating in
accordance with subparagraphs 5 −6−7b, 5−6−7c,
5−6−7d, and 5−6−7e) are authorized to transit U.S.
territorial airspace if in compliance with all of thefollowing conditions:
1.File and are on an active flight plan (IFR,
VFR, or DVFR);
2.Equipped with an operational transponder
with altitude reporting capability and continuously
squawk an ATC assigned transponder code;
3.Maintain two −way radio communications
with ATC;
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph5−6−2;
5.Are operating under an approved TSA
aviation security program (see paragraph 5 −6−10 for
TSA aviation security program information) or are
operating with and in accordance with an FAA/TSA
airspace waiver (see paragraph 5 −6−9 for F AA/TSA
airspace waiver information), if:
(a)The aircraft is not registered in the U.S.; or
(b)The aircraft is registered in the U.S. and its
maximum takeoff gross weight is greater than100,309 pounds (45,500 kgs);
6.Are in receipt of, and are operating in
accordance with, an FAA routing authorization if the
aircraft is registered in a U.S. State Department −des-
ignated special interest country or is operating with
the ICAO 3LD of a company in a country listed as a
U.S. State Department −designated special interest
country, unless the operator holds valid FAA Part 129
operations specifications. VFR and DVFR flightoperations are prohibited for any aircraft requiring an
FAA routing authorization. (See paragraph 5 −6−11
for FAA routing authorization information.)
b.Civil aircraft registered in Canada or Mexico,
and engaged in operations for the purposes of air
ambulance, firefighting, law enforcement, search and
rescue, or emergency evacuation are authorized totransit U.S. territorial airspace within 50 NM of their
respective borders with the U.S., with or without an
active flight plan, provided they have received andcontinuously transmit an ATC −assigned transponder
code.
c.Civil aircraft registered in Canada, Mexico,
Bahamas, Bermuda, Cayman Islands, or the British
Virgin Islands with a maximum certificated takeoff
gross weight of 100,309 pounds (45,500 kgs) or lessare authorized to transit U.S. territorial airspace if in
compliance with all of the following conditions:
1.File and are on an active flight plan (IFR,
VFR, or DVFR) that enters U.S. territorial airspace
directly from any of the countries listed in this
subparagraph 5 −6−7c. Flights that include a stop in a
non−listed country prior to entering U.S. territorial
airspace must comply with the requirements
prescribed by subparagraph 5 −6−7a above, including
operating under an approved TSA aviation security
program (see paragraph 5 −6−10 for TSA aviation
program information) or operating with, and inaccordance with, an FAA/TSA airspace waiver (see
paragraph 5 −6−9 for FAA/TSA airspace waiver
information).
2.Equipped with an operational transponder
with altitude reporting capability and continuously
squawk an ATC assigned transponder code; and
3.Maintain two −way radio communications
with ATC.
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph
5−6−2.
d.Civil aircraft registered in Canada, Mexico,
Bahamas, Bermuda, Cayman Islands, or the British
Virgin Islands with a maximum certificated takeoff
gross weight greater than 100,309 pounds(45,500 kgs) must comply with the requirements
subparagraph 5 −6−7a, including operating under an
approved TSA aviation security program (seeparagraph 5 −6−10 for TSA aviation program
information) or operating with, and in accordance
with, an FAA/TSA airspace waiver (see paragraph
5−6−9 for FAA/TSA airspace waiver information).
e.Civil aircraft registered in the U.S., Canada, or
Mexico with a maximum certificated takeoff gross
weight of 100,309 pounds (45,500 kgs) or less that are
operating without an operational transponder and/or
the ability to maintain two −way radio communica-
tions with ATC, are authorized to transit U.S.
territorial airspace over Alaska if in compliance with
all of the following conditions:
AIM 10/12/17
5−6−6 National Security and Interception Procedures1.Enter and exit U.S. territorial airspace over
Alaska north of the fifty −fourth parallel;
2.File and are on an active flight plan;
3.Squawk 1200 if VFR and equipped with a
transponder.
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph5−6−2.
5−6−8. Foreign State Aircraft Operations
a.Foreign state aircraft are authorized to operate
in U.S. territorial airspace if in compliance with all ofthe following conditions:
1.File and are on an active IFR flight plan;
2.Equipped with an operational transponder
with altitude reporting capability and continuously
squawk an ATC assigned transponder code;
3.Maintain two −way radio communications
with ATC;
4.Comply with all other applicable ADIZ
requirements described in paragraph 5 −6−4 and any
other national security requirements in paragraph
5−6−2.
b. Diplomatic Clearances. Foreign state aircraft
may operate to or from, within, or in transit of U.S.
territorial airspace only when authorized by the U.S.
State Department by means of a diplomatic
clearance, except as described in subparagraph
5−6−8h below.
1.Information about diplomatic clearances is
available at the U.S. State Department website
http://www.state.gov/t/pm/iso/c56895.htm (lowercase only).
2.A diplomatic clearance may be initiated by
contacting the U.S. State Department via email atDCAS@state.gov or via phone at (202) 663 −3390.
NOTE−
A diplomatic clearance is not required for foreign stateaircraft operations that tr ansit U.S. controlled oceanic
airspace but do not enter U.S. territorial airspace. (See
subparagraph 5 −6−8d for flight plan information.)
c.An FAA routing authorization for state aircraft
operations of special interest countries listed in
subparagraph 5 −6−11b. is required before the U.S.State Department will issue a diplomatic clearance
for such operations. (See subparagraph 5 −6−11 for
FAA routing authorizations information).
d.Foreign state aircraft operating with a diplomat-
ic clearance must navigate U.S. territorial airspace onan active IFR flight plan, unless specifically
approved for VFR flight operations by the U.S. State
Department in the diplomatic clearance.
NOTE−
Foreign state aircraft operations to or from, within, ortransiting U.S. territorial airspac e; or transiting any U.S.
controlled oceanic airspace, should enter ICAO code M in
Item 8 of the flight plan to assist in identification of theaircraft as a state aircraft.
e.A foreign aircraft that operates to or from,
within, or in transit of U.S. territorial airspace while
conducting a state aircraft operation is not authorized
to change its status as a state aircraft during any
portion of the approved, diplomatically cleared
itinerary.
f.A foreign aircraft described in subparagraph
5−6−8e above may operate from or within U.S.
territorial airspace as a civil aircraft operation, once
it has completed its approved, diplomatically cleared
itinerary, if the aircraft operator is:
1.A foreign air carrier that holds valid FAA Part
129 operations specifications; and
2.Is in compliance with all other requirements
applied to foreign civil aircraft operations from or
within U.S. territorial airspace. (See paragraphs
5−6−5 and 5−6−6.)
g.Foreign state aircraft operations are not
authorized to or from Ronald Reagan WashingtonNational Airport (KDCA).
h. Diplomatic Clearance Exceptions. State
aircraft operations on behalf of the governments ofCanada and Mexico conducted for the purposes of air
ambulance, firefighting, law enforcement, search and
rescue, or emergency evacuation are authorized totransit U.S. territorial airspace within 50 NM of their
respective borders with the U.S., with or without an
active flight plan, provided they have received andcontinuously transmit an ATC assigned transponder
code. State aircraft operations on behalf of the
governments of Canada and Mexico conducted under
this subparagraph 5 −6−8h are not required to obtain
a diplomatic clearance from the U.S. State
Department.
AIM 10/12/17
5−6−7 National Security and Interception Procedures5−6−9. FAA/TSA Airspace Waivers
a.Operators may submit requests for FAA/TSA
airspace waivers at https://waivers.faa.gov byselecting “international” as the waiver type.
b.Information regarding FAA/TSA airspace
waivers can be found at: http://www .tsa.gov/for −in-
dustry/general −aviation or can be obtained by
contacting TSA at (571) 227 −2071.
c.All existing FAA/TSA waivers issued under
previous FDC NOTAMS remain valid until the
expiration date specified in the waiver, unless sooner
superseded or rescinded.
5−6−10. TSA Aviation Security Programs
a.Applicants for U.S. air operator certificates will
be provided contact information for TSA aviation
security programs by the U.S. Department ofTransportation during the certification process.
b.For information about applicable TSA security
programs:
1.U.S. air carriers and commercial operators
must contact their TSA Principal Security Specialist(PSS); and
2.Foreign air carriers must contact their
International Industry Representative (IIR).
5−6−11. FAA Flight Routing Authorizations
a.Information about FAA routing authorizations
for U.S. State Department −designated special
interest country flight operations to or from, within,
or transiting U.S. territorial airspace is available by
country at:
1.FAA website http://www.faa.gov/air_traffic/
publications/us_restrictions/; or
2.Phone by contacting the FAA System
Operations Support Center (SOSC) at
(202) 267 −8115.
b.Special Interest Countries. The U.S. State
Department −designated special interest countries areCuba, Iran, The Democratic People’s Republic of
Korea (North Korea), The People’s Republic of
China, The Russian Federation, Sudan, and Syria.
NOTE−
F AA flight routing authorizations are not required for
aircraft registered in Hong Kong, Taiwan, or Macau.
c.Aircraft operating with the ICAO 3LD assigned
to a company or entity from a country listed as a State
Department −designated special interest country and
holding valid FAA Part 129 operations specifications
do not require FAA flight routing authorization.
d.FAA routing authorizations will only be granted
for IFR operations. VFR and DVFR flight operations
are prohibited for any aircraft requiring an FAA
routing authorization.
5−6−12. Emergency Security Control of Air
Traffic (ESCAT)
a.During defense emergency or air defense
emergency conditions, additional special securityinstructions may be issued in accordance with
32 CFR Part 245, Plan for the Emergency Security
Control of Air Traffic (ESCAT) .
b.Under the provisions of 32 CFR Part 245, the
military will direct the action to be taken in regard to
landing, grounding, diversion, or dispersal of aircraft
in the defense of the U.S. during emergency
conditions.
c.At the time a portion or all of ESCAT is
implemented, A TC facilities will broadcast appropri-
ate instructions received from the Air Traffic Control
System Command Center (ATCSCC) over available
ATC frequencies. Depending on instructions re-ceived from the ATCSCC, VFR flights may be
directed to land at the nearest available airport, and
IFR flights will be expected to proceed as directed byATC.
d.Pilots on the ground may be required to file a
flight plan and obtain an approval (through FAA)prior to conducting flight operation.
AIM 10/12/17
5−6−8 National Security and Interception Procedures5−6−13. Interception Procedures
a. General.
1.In conjunction with the FAA, Air Defense
Sectors monitor air traffic and could order anintercept in the interest of national security or
defense. Intercepts during peacetime operations are
vastly different than those conducted under increased
states of readiness. The interceptors may be fighters
or rotary wing aircraft. The reasons for aircraft
intercept include, but are not limited to:
(a)Identify an aircraft;
(b)Track an aircraft;
(c)Inspect an aircraft;
(d)Divert an aircraft;
(e)Establish communications with an air-
craft.
2.When specific information is required (i.e.,
markings, serial numbers, etc.) the interceptor
pilot(s) will respond only if, in their judgment, the
request can be conducted in a safe manner. Interceptprocedures are described in some detail in the
paragraphs below. In all situations, the interceptor
pilot will consider safety of flight for all concerned
throughout the intercept procedure. The interceptor
pilot(s) will use caution to avoid startling theintercepted crew or passengers and understand that
maneuvers considered normal for interceptor aircraft
may be considered hazardous to other aircraft.
3.All aircraft operating in US national airspace
are highly encouraged to maintain a listening watch
on VHF/UHF guard frequencies (121.5 or 243.0
MHz). If subjected to a military intercept, it isincumbent on civilian aviators to understand their
responsibilities and to comply with ICAO standard
signals relayed from the intercepting aircraft.Specifically, aviators are expected to contact air
traffic control without delay (if able) on the local
operating frequency or on VHF/UHF guard.
Noncompliance may result in the use of force.
b. Fighter intercept phases (See FIG 5−6−1).
1. Approach Phase.
As standard procedure, intercepted aircraft areapproached from behind. Typically, interceptor
aircraft will be employed in pairs, however, it is not
uncommon for a single aircraft to perform theintercept operation. Safe separation between inter-
ceptors and intercepted aircraft is the responsibility of
the intercepting aircraft and will be maintained at all
times.
2. Identification Phase.
Interceptor aircraft will initiate a controlled closure
toward the aircraft of interest, holding at a distance no
closer than deemed necessary to establish positiveidentification and to gather the necessary informa-
tion. The interceptor may also fly past the intercepted
aircraft while gathering data at a distance considered
safe based on aircraft performance characteristics.
3. Post Intercept Phase.
An interceptor may attempt to establish communica-
tions via standard ICAO signals. In time-critical
situations where the interceptor is seeking animmediate response from the intercepted aircraft or if
the intercepted aircraft remains non-compliant to
instruction, the interceptor pilot may initiate a divert
maneuver. In this maneuver, the interceptor flies
across the intercepted aircraft’s flight path (minimum
500 feet separation and commencing from slightlybelow the intercepted aircraft altitude) in the general
direction the intercepted aircraft is expected to turn.
The interceptor will rock its wings (daytime) or flashexternal lights/select afterburners (night) while
crossing the intercepted aircraft’s flight path. The
interceptor will roll out in the direction the
intercepted aircraft is expected to turn before
returning to verify the aircraft of interest iscomplying. The intercepted aircraft is expected to
execute an immediate turn to the direction of the
intercepting aircraft. If the aircraft of interest does not
comply, the interceptor may conduct a second
climbing turn across the intercepted aircraft’s flight
path (minimum 500 feet separation and commencing
from slightly below the intercepted aircraft altitude)
while expending flares as a warning signal to theintercepted aircraft to comply immediately and toturn in the direction indicated and to leave the area.
The interceptor is responsible to maintain safe
separation during these and all intercept maneuvers.Flight safety is paramount.
NOTE−
1.NORAD interceptors will take every precaution to
preclude the possibility of the intercepted aircraftexperiencing jet wash/wake turbulence; however, there isa potential that this condition could be encountered.
2.During Night/IMC, the intercept will be from below
flight path.
AIM 10/12/17
5−6−9 National Security and Interception ProceduresFIG 5−6−1
Intercept Procedures
c. Helicopter Intercept phases (See FIG 5−6−2)
1.Approach Phase.
Aircraft intercepted by helicopter may be approached
from any direction, although the helicopter shouldclose for identification and signaling from behind.
Generally, the helicopter will approach off the left
side of the intercepted aircraft. Safe separation
between the helicopter and the unidentified aircraft
will be maintained at all times.
2. Identification Phase.
The helicopter will initiate a controlled closuretoward the aircraft of interest, holding at a distance no
closer than deemed necessary to establish positive
identification and gather the necessary information.
The intercepted pilot should expect the interceptor
helicopter to take a position off his left wing slightly
forward of abeam.3. Post Intercept Phase.
Visual signaling devices may be used in an attempt to
communicate with the intercepted aircraft. Visual
signaling devices may include, but are not limited to,
LED scrolling signboards or blue flashing lights. Ifcompliance is not attained through the use of radios
or signaling devices, standard ICAO intercept signals
(Table 5-6-1) may be employed. In order to maintain
safe aircraft separation, it is incumbent upon the pilot
of the intercepted aircraft not to fall into a trail
position (directly behind the helicopter) if instructedto follow the helicopter. This is because the helicopter
pilot may lose visual contact with the intercepted
aircraft.
NOTE−
Intercepted aircraft must not follow directly behind the
helicopter thereby allowing the helicopter pilot to maintain
visual contact with the intercepted aircraft and ensuringsafe separation is maintained.
AIM 10/12/17
5−6−10 National Security and Interception ProceduresFIG 5−6−2
Helicopter Intercept Procedures
d.Summary of Intercepted Aircraft Actions. An
intercepted aircraft must, without delay:
1.Adhere to instructions relayed through the
use of visual devices, visual signals, and radio
communications from the intercepting aircraft.
2.Attempt to establish radio communications
with the intercepting aircraft or with the appropriate
air traffic control facility by making a general call on
guard frequencies (121.5 or 243.0 MHz), giving the
identity, position, and nature of the flight.
3.If transponder equipped, select Mode 3/A
Code 7700 unless otherwise instructed by air traffic
control.
NOTE−
If instruction received from any agency conflicts with thatgiven by the intercepting aircraft through visual or radiocommunications, the intercepted aircraft must seek
immediate clarification.
4.The crew of the intercepted aircraft must
continue to comply with interceptor aircraft signals
and instructions until positively released.5−6−14. Law Enforcement Operations by
Civil and Military Organizations
a. Special law enforcement operations.
1.Special law enforcement operations include
in-flight identification, surveillance, interdiction, and
pursuit activities performed in accordance with
official civil and/or military mission responsibilities.
2.To facilitate accomplishment of these special
missions, exemptions from specified sections of the
CFRs have been granted to designated departments
and agencies. However, it is each organization’sresponsibility to apprise ATC of their intent to operate
under an authorized exemption before initiating
actual operations.
3.Additionally, some departments and agencies
that perform special missi ons have been assigned
coded identifiers to permit them to apprise ATC ofongoing mission activities and solicit special
air traffic assistance.
AIM 10/12/17
5−6−11 National Security and Interception Procedures5−6−15. Interception Signals
TBL 5−6−1 and TBL 5 −6−2.
TBL 5−6−1
Intercepting Signals
INTERCEPTING SIGNALS
Signals initiated by intercepting aircraft and responses by intercepted aircraft
(as set forth in ICAO Annex 2-Appendix 1, 2.1)
Series INTERCEPTING Aircraft Signals Meaning INTERCEPTED Aircraft Responds Meaning
1 DAY−Rocking wings from a position
slightly above and ahead of, and normally
to the left of, the intercepted aircraft and,after acknowledgement, a slow level turn,normally to the left, on to the desiredheading.
NIGHT-Same and, in addition, flashing
navigational lights at irregular intervals.
NOTE 1−Meteorological conditions or
terrain may require the intercepting
aircraft to take up a position slightly above
and ahead of, and to the right of, theintercepted aircraft and to make thesubsequent turn to the right.
NOTE 2−If the intercepted aircraft is not
able to keep pace with the interceptingaircraft, the latter is expected to fly a series
of race−track patterns and to rock its wings
each time it passes the inter cepted aircraft.You have
been
intercepted.Follow me.AEROPLANES:
DAY−Rocking wings and following.
NIGHT−Same and, in addition, flashing
navigational lights at irregular intervals.
HELICOPTERS:
DAY or NIGHT −Rocking aircraft, flashing
navigational lights at irregular intervals and
following.Understood,
will comply.
2 DAY or NIGHT −An abrupt break −away
maneuver from the intercepted aircraft
consisting of a climbing turn of 90 degrees
or more without crossing the line of flightof the intercepted aircraft.You may
proceed.AEROPLANES:DAY or NIGHT-Rocking wings.
HELICOPTERS:
DAY or NIGHT −Rocking aircraft.Understood,
will comply.
3 DAY−Circling aerodrome, lowering land-
ing gear and overflying runway in direction
of landing or, if the intercepted aircraft is ahelicopter, overflying the helicopter land-ing area.
NIGHT−Same and, in addition, showing
steady landing lights.Land at thisaerodrome. AEROPLANES:DAY−Lowering landing gear, following
the intercepting aircraft and, if afteroverflying the runway landing is consid-ered safe, proceeding to land.
NIGHT−Same and, in addition, showing
steady landing lights (if carried).
HELICOPTERS:
DAY or NIGHT -Following the intercepting
aircraft and proceeding to land, showing a
steady landing light (if carried).Understood,will comply.
AIM 10/12/17
5−6−12 National Security and Interception ProceduresTBL 5−6−2
Intercepting Signals
INTERCEPTING SIGNALS
Signals and Responses During Aircraft Intercept
Signals initiated by intercepted aircraft and responses by intercepting aircraft
(as set forth in ICAO Annex 2-Appendix 1, 2.2)
Series INTERCEPTED Aircraft Signals Meaning INTERCEPTING Aircraft Responds Meaning
4 DAY or NIGHT −Raising landing gear (if
fitted) and flashing landing lights while
passing over runway in use or helicopterlanding area at a height exceeding 300m(1,000 ft) but not exceeding 600m(2,000 ft) (in the case of a helicopter, at aheight exceeding 50m (170 ft) but not
exceeding 100m (330 ft) above the
aerodrome level, and continuing to circlerunway in use or helicopter landing area. If
unable to flash landing lights, flash anyother lights available.Aerodrome
you have
designated isinadequate.DAY or NIGHT −If it is desired that the
intercepted aircraft follow the intercepting
aircraft to an alternate aerodrome, theintercepting aircraft raises its landing gear(if fitted) and uses the Series 1 signalsprescribed for intercepting aircraft.
If it is decided to release the intercepted
aircraft, the intercepting aircraft uses theSeries 2 signals prescribed for interceptingaircraft.Understood,
follow me.
Understood,
you mayproceed.
5 DAY or NIGHT −Regular switching on and
off of all available lights but in such a
manner as to be distinct from flashinglights.Cannot
comply.DAY or NIGHT-Use Series 2 signalsprescribed for intercepting aircraft. Understood.
6 DAY or NIGHT −Irregular flashing of all
available lights.In distress. DAY or NIGHT-Use Series 2 signalsprescribed for intercepting aircraft. Understood.
AIM 10/12/17
5−6−13 National Security and Interception Procedures5−6−16. ADIZ Boundaries and Designated Mountainous Areas (See FIG 5−6−3.)
FIG 5−6−3
Air Defense Identification Zone Boundaries
Designated Mountainous Areas
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AIM 10/12/17
5−6−14 National Security and Interception Procedures5−6−17. Visual Warning System (VWS)
The VWS signal consists of highly-focused red and
green colored laser lights designed to illuminate in an
alternating red and green signal pattern. These lasers
may be directed at specific aircraft suspected ofmaking unauthorized entry into the Washington, DC
Special Flight Rules Area (DC SFRA) proceeding on
a heading or flight path that may be interpreted as athreat or that operate contrary to the operating rules
for the DC SFRA. The beam is neither hazardous to
the eyes of pilots/aircrew or passengers, regardless ofaltitude or distance from the source nor will the beam
affect aircraft systems.
a.If you are communicating with ATC, and this
signal is directed at your aircraft, you are required tocontact ATC and advise that you are being
illuminated by a visual warning system.
b.If this signal is directed at you, and you are not
communicating with ATC, you are advised to turn to
the most direct heading away from the center of the
DC SFRA as soon as possible. Immediately contactATC on an appropriate frequency, VHF Guard 121.5
or UHF Guard 243.0, and provide your aircraft
identification, position, and nature of the flight.
Failure to follow these procedures may result in
interception by military aircraft. Further noncompli-ance with interceptor aircraft or A TC may result in the
use of force.
c.Pilots planning to operate aircraft in or near the
DC SFRA are to familiarize themselves with aircraftintercept procedures. This information applies to all
aircraft operating within the DC SFRA including
DOD, Law Enforcement, and aircraft engaged inaeromedical operations and does not change
procedures established for reporting unauthorized
laser illumination as published in FAA AdvisoryCirculars and Notices.
REFERENCE −
CFR 91.161
d.More details including a video demonstration of
the VWS are available from the following FAAwebsite: www.faasafety.gov/VisualWarningSystem
/VisualWarning.htm.
AIM 10/12/17
6−1−1 GeneralChapter 6. Emergency Procedures
Section 1. General
6−1−1. Pilot Responsibility and Authority
a.The pilot−in−command of an aircraft is directly
responsible for and is the final authority as to theoperation of that aircraft. In an emergency requiring
immediate action, the pilot −in−command may
deviate from any rule in 14 CFR Part 91, Subpart A,General, and Subpart B, Flight Rules, to the extent
required to meet that emergency.
REFERENCE −
14 CFR Section 91.3(b).
b.If the emergency authority of 14 CFR
Section 91.3(b) is used to deviate from the provisions
of an ATC clearance, the pilot −in−command must
notify ATC as soon as possible and obtain an
amended clearance.
c.Unless deviation is necessary under the
emergency authority of 14 CFR Section 91.3, pilots
of IFR flights experiencing two-way radio commu-
nications failure are expected to adhere to theprocedures prescribed under “IFR operations,
two-way radio communications failure.”
REFERENCE −
14 CFR Section 91.185.6−1−2. Emergency Condition − Request
Assistance Immediately
a.An emergency can be either a distress or
urgency condition as defined in the Pilot/Controller
Glossary. Pilots do not hesitate to declare anemergency when they are faced with distress
conditions such as fire, mechanical failure, or
structural damage. However, some are reluctant toreport an urgency condition when they encounter
situations which may not be immediately perilous,
but are potentially catastrophic. An aircraft is in at
least an urgency condition the moment the pilot
becomes doubtful about position, fuel endurance,weather, or any other condition that could adversely
affect flight safety. This is the time to ask for help, not
after the situation has developed into a distress
condition.
b.Pilots who become apprehensive for their safety
for any reason should request assistance immediately.
Ready and willing help is available in the form ofradio, radar, direction finding stations and other
aircraft. Delay has caused accidents and cost lives.
Safety is not a luxury! Take action!
AIM 10/12/17
6−2−1 Emergency Services Available to PilotsSection 2. Emergency Services Available to Pilots
6−2−1. Radar Service for VFR Aircraft in
Difficulty
a.Radar equipped ATC facilities can provide
radar assistance and navigation service (vectors) toVFR aircraft in difficulty when the pilot can talk with
the controller, and the aircraft is within radar
coverage. Pilots should clearly understand thatauthorization to proceed in accordance with such
radar navigational assistance does not constitute
authorization for the pilot to violate CFRs. In effect,assistance is provided on the basis that navigational
guidance information is advisory in nature, and the
responsibility for flying the aircraft safely remainswith the pilot.
b.Experience has shown that many pilots who are
not qualified for instrument flight cannot maintain
control of their aircraft when they encounter clouds
or other reduced visibility conditions. In many cases,the controller will not know whether flight into
instrument conditions will result from ATC instruc-
tions. To avoid possible hazards resulting from being
vectored into IFR conditions, a pilot in difficulty
should keep the controller advised of the currentweather conditions being encountered and the
weather along the course ahead and observe the
following:
1.If a course of action is available which will
permit flight and a safe landing in VFR weatherconditions, noninstrument rated pilots should choose
the VFR condition rather than requesting a vector or
approach that will take them into IFR weatherconditions; or
2.If continued flight in VFR conditions is not
possible, the noninstrument rated pilot should so
advise the controller and indicating the lack of an
instrument rating, declare a distress condition; or
3.If the pilot is instrument rated and current, and
the aircraft is instrument equipped, the pilot should so
indicate by requesting an IFR flight clearance.
Assistance will then be provided on the basis that theaircraft can operate safely in IFR weather conditions.6−2−2. Transponder Emergency Operation
a.When a distress or urgency condition is
encountered, the pilot of an aircraft with a coded radar
beacon transponder, who desires to alert a groundradar facility, should squawk Mode 3/A,
Code 7700/Emergency and Mode C altitude report-
ing and then immediately establish communicationswith the ATC facility.
b.Radar facilities are equipped so that Code 7700
normally triggers an alarm or special indicator at all
control positions. Pilots should understand that theymight not be within a radar coverage area. Therefore,
they should continue squawking Code 7700 and
establish radio communications as soon as possible.
6−2−3. Intercept and Escort
a.The concept of airborne intercept and escort is
based on the Search and Rescue (SAR) aircraft
establishing visual and/or electronic contact with anaircraft in difficulty, providing in-flight assistance,
and escorting it to a safe landing. If bailout, crash
landing or ditching becomes necessary, SARoperations can be conducted without delay. For most
incidents, particularly those occurring at night and/or
during instrument flight conditions, the availabilityof intercept and escort services will depend on the
proximity of SAR units with suitable aircraft on alert
for immediate dispatch. In limited circumstances,other aircraft flying in the vicinity of an aircraft in
difficulty can provide these services.
b.If specifically requested by a pilot in difficulty
or if a distress condition is declared, SAR
coordinators will take steps to intercept and escort an
aircraft. Steps may be initiated for intercept and
escort if an urgency condition is declared and unusual
circumstances make such action advisable.
c.It is the pilot’s prerogative to refuse intercept
and escort services. Escort services will normally be
provided to the nearest adequate airport. Should thepilot receiving escort services continue onto another
location after reaching a safe airport, or decide not to
divert to the nearest safe airport, the escort aircraft is
not obligated to continue and further escort is
AIM 10/12/17
6−2−2 Emergency Services Available to Pilotsdiscretionary. The decision will depend on the
circumstances of the individual incident.
6−2−4. Emergency Locator Transmitter
(ELT)
a. General.
1.ELTs are required for most General Aviation
airplanes.
REFERENCE −
14 CFR SECTION 91.207.
2.ELTs of various types were developed as a
means of locating downed aircraft. These electronic,
battery operated transmitters operate on one of three
frequencies. These operating frequencies are121.5 MHz, 243.0 MHz, and the newer 406 MHz.
ELTs operating on 121.5 MHz and 243.0 MHz are
analog devices. The newer 406 MHz ELT is a digital
transmitter that can be encoded with the owner’s
contact information or aircraft data. The latest
406 MHz ELT models can also be encoded with theaircraft’s position data which can help SAR forces
locate the aircraft much more quickly after a crash.
The 406 MHz ELTs also transmits a stronger signalwhen activated than the older 121.5 MHz ELTs.
(a)The Federal Communications Commis-
sion (FCC) requires 406 MHz ELTs be registered
with the National Oceanic and Atmospheric
Administration (NOAA) as outlined in the ELTsdocumentation. The FAA’s 406 MHz ELT Technical
Standard Order (TSO) TSO −C126 also requires that
each 406 MHz ELT be registered with NOAA. Thereason is NOAA maintains the owner registration
database for U.S. registered 406 MHz alerting
devices, which includes ELTs. NOAA also operatesthe United States’ portion of the Cospas −Sarsat
satellite distress alerting system designed to detect
activated ELTs and other distress alerting devices.
(b)In the event that a properly registered
406 MHz ELT activates, the Cospas −Sarsat satellite
system can decode the owner’s information and
provide that data to the appropriate search and
rescue (SAR) center. In the United States, NOAAprovides the alert data to the appropriate U.S. Air
Force Rescue Coordination Center (RCC) or U.S.
Coast Guard Rescue Coordination Center. That RCC
can then telephone or contact the owner to verify the
status of the aircraft. If the aircraft is safely secured
in a hangar, a costly ground or airborne search isavoided. In the case of an inadvertent 406 MHz ELT
activation, the owner can deactivate the 406 MHz
ELT. If the 406 MHz ELT equipped aircraft is being
flown, the RCC can quickly activate a search.
406 MHz ELTs permit the Cospas −Sarsat satellite
system to narrow the search area to a more confined
area compared to that of a 121.5 MHz or 243.0 MHz
ELT. 406 MHz ELTs also include a low −power
121.5 MHz homing transmitter to aid searchers in
finding the aircraft in the terminal search phase.
(c)Each analog ELT emits a distinctive
downward swept audio tone on 121.5 MHz and243.0 MHz.
(d)If “armed” and when subject to crash −
generated forces, ELTs are designed to automatically
activate and continuously emit their respectivesignals, analog or digital. The transmitters will
operate continuously for at least 48 hours over a wide
temperature range. A properly installed, maintained,and functioning ELT can expedite search and rescue
operations and save lives if it survives the crash and
is activated.
(e)Pilots and their passengers should know
how to activate the aircraft’s ELT if manual activation
is required. They should also be able to verify the
aircraft’s ELT is functioning and transmitting an alert
after a crash or manual activation.
(f)Because of the large number of 121.5 MHz
ELT false alerts and the lack of a quick means of
verifying the actual status of an activated 121.5 MHz
or 243.0 MHz analog ELT through an owner
registration database, U.S. SAR forces do not
respond as quickly to initial 121.5/243.0 MHz ELTalerts as the SAR forces do to 406 MHz ELT alerts.
Compared to the almost instantaneous detection of a
406 MHz ELT, SAR forces’ normal practice is to wait
for either a confirmation of a 121.5/243.0 MHz alert
by additional satellite passes or through confirmation
of an overdue aircraft or similar notification. In somecases, this confirmation process can take hours. SAR
forces can initiate a response to 406 MHz alerts in
minutes compared to the potential delay of hours for
a 121.5/243.0 MHz ELT.
The Cospas −Sarsat system has announced the
termination of satellite monitoring and reception of
the 121.5 MHz and 243.0 MHz frequencies in 2009.The Cospas −Sarsat system will continue to monitor
the 406 MHz frequency. What this means for pilots is
that after the termination date, those aircraft with only
AIM 10/12/17
6−2−3 Emergency Services Available to Pilots121.5 MHz or 243.0 MHz ELT’s onboard will have
to depend upon either a nearby Air Traffic Control
facility receiving the alert signal or an overflying
aircraft monitoring 121.5 MHz or 243.0 MHz
detecting the alert. To ensure adequate monitoring of
these frequencies and timely alerts after 2009, all
airborne pilots should periodically monitor these
frequencies to try and detect an activated121.5/243.0 MHz ELT.
b. Testing.
1.ELTs should be tested in accordance with the
manufacturer’s instructions, preferably in a shielded
or screened room or specially designed test container
to prevent the broadcast of signals which could
trigger a false alert.
2.When this cannot be done, aircraft operation-
al testing is authorized as follows:
(a)Analog 121.5/243 MHz ELTs should only
be tested during the first 5 minutes after any hour. If
operational tests must be made outside of this period,
they should be coordinated with the nearest FAA
Control Tower. Tests should be no longer than three
audible sweeps. If the antenna is removable, a
dummy load should be substituted during test
procedures.
(b)Digital 406 MHz ELTs should only be
tested in accordance with the unit’s manufacturer’s
instructions.
(c)
Airborne tests are not authorized.
c. False Alarms.
1.Caution should be exercised to prevent the
inadvertent activation of ELTs in the air or while they
are being handled on the ground. Accidental or
unauthorized activation will generate an emergency
signal that cannot be distinguished from the realthing, leading to expensive and frustrating searches.
A false ELT signal could also interfere with genuine
emergency transmissions and hinder or prevent thetimely location of crash sites. Frequent false alarms
could also result in complacency and decrease the
vigorous reaction that must be attached to all ELTsignals.
2.Numerous cases of inadvertent activation
have occurred as a result of aerobatics, hard landings,
movement by ground crews and aircraft mainte-nance. These false alarms can be minimized by
monitoring 121.5 MHz and/or 243.0 MHz as follows:
(a)In flight when a receiver is available.
(b)Before engine shut down at the end of
each flight.
(c)When the ELT is handled during installa-
tion or maintenance.
(d)When maintenance is being performed
near the ELT.
(e)When a ground crew moves the aircraft.
(f)If an ELT signal is heard, turn off the
aircraft’s ELT to determine if it is transmitting. If it
has been activated, maintenance might be requiredbefore the unit is returned to the “ARMED” position.
You should contact the nearest Air Traf fic facility and
notify it of the inadvertent activation.
d. Inflight Monitoring and Reporting.
1.Pilots are encouraged to monitor 121.5 MHz
and/or 243.0 MHz while inflight to assist in
identifying possible emergency ELT transmissions.
On receiving a signal, report the following
information to the nearest air traffic facility:
(a)Your position at the time the signal was
first heard.
(b)Your position at the time the signal was
last heard.
(c)Your position at maximum signal
strength.
(d)Your flight altitudes and frequency on
which the emergency signal was heard: 121.5 MHz or
243.0 MHz. If possible, positions should be given
relative to a navigation aid. If the aircraft has homing
equipment, provide the bearing to the emergency
signal with each reported position.
6−2−5. FAA K −9 Explosives Detection
Team Program
a.The FAA’s Office of Civil Aviation Security
Operations manages the FAA K −9 Explosives
Detection Team Program which was established in
1972. Through a unique agreement with law
enforcement agencies and airport authorities, theFAA has strategically placed FAA −certified K −9
teams (a team is one handler and one dog) at airports
throughout the country. If a bomb threat is received
AIM 10/12/17
6−2−4 Emergency Services Available to Pilotswhile an aircraft is in flight, the aircraft can be
directed to an airport with this capability. The FAA
provides init ial and refresher training for all handlers,
provides single purpose explosive detector dogs, and
requires that each team is annually evaluated in fiveareas for FAA certification: aircraft (widebody and
narrowbody), vehicles, terminal, freight (cargo), and
luggage. If you desire this service, notify your
company or an FAA air traffic control facility.
b.The following list shows the locations of
current FAA K −9 teams:
TBL 6−2−1
FAA Sponsored Explosives Detection
Dog/Handler Team Locations
Airport Symbol Location
ATL Atlanta, Georgia
BHM Birmingham, Alabama
BOS Boston, Massachusetts
BUF Buffalo, New York
CLT Charlotte, North Carolina
ORD Chicago, Illinois
CVG Cincinnati, Ohio
DFW Dallas, Texas
DEN Denver, Colorado
DTW Detroit, Michigan
IAH Houston, Texas
JAX Jacksonville, Florida
MCI Kansas City, Missouri
LAX Los Angeles, California
MEM Memphis, Tennessee
MIA Miami, Florida
MKE Milwaukee, Wisconsin
MSY New Orleans, Louisiana
MCO Orlando, Florida
PHX Phoenix, Arizona
PIT Pittsburgh, Pennsylvania
PDX Portland, Oregon
SLC Salt Lake City, Utah
SFO San Francisco, California
SJU San Juan, Puerto Rico
SEA Seattle, WashingtonSTL St. Louis, Missouri
TUS Tucson, Arizona
TUL Tulsa, Oklahoma
c.If due to weather or other considerations an
aircraft with a suspected hidden explosive problemwere to land or intended to land at an airport other
than those listed in b above, it is recommended that
they call the FAA’s Washington Operations Center(telephone 202 −267−3333, if appropriate) or have an
air traffic facility with which you can communicate
contact the above center requesting assistance.
6−2−6. Search and Rescue
a. General. SAR is a lifesaving service provided
through the combined efforts of the federal agencies
signatory to the National SAR Plan, and the agencies
responsible for SAR within each state. Operationalresources are provided by the U.S. Coast Guard,
DOD components, the Civil Air Patrol, the Coast
Guard Auxiliary, state, county and local lawenforcement and other public safety agencies, and
private volunteer organizations. Services include
search for missing aircraft, survival aid, rescue, andemergency medical help for the occupants after an
accident site is located.
b. National Search and Rescue Plan. By federal
interagency agreement, the National Search and
Rescue Plan provides for the effective use of allavailable facilities in all types of SAR missions.
These facilities include aircraft, vessels, pararescue
and ground rescue teams, and emergency radio
fixing. Under the plan, the U.S. Coast Guard is
responsible for the coordination of SAR in theMaritime Region, and the USAF is responsible in the
Inland Region. To carry out these responsibilities, the
Coast Guard and the Air Force have establishedRescue Coordination Centers (RCCs) to direct SAR
activities within their regions. For aircraft emergen-
cies, distress, and ur gency, information normally will
be passed to the appropriate RCC through an ARTCC
or FSS.
c. Coast Guard Rescue Coordination Centers.
(See TBL 6 −2−2.)
AIM 10/12/17
6−2−5 Emergency Services Available to PilotsTBL 6−2−2
Coast Guard Rescue Coordination Centers
Coast Guard Rescue Coordination Centers
Alameda, CA
510−437−3701Miami, FL
305−415−6800
Boston, MA
617−223−8555New Orleans, LA
504−589−6225
Cleveland, OH
216−902−6117Portsmouth, V A
757−398−6390
Honolulu, HI
808−541−2500Seattle, WA
206−220−7001
Juneau, AK
907−463−2000San Juan, PR
787−289−2042
d. Air Force Rescue Coordination Centers.
(See TBL 6 −2−3 and TBL 6 −2−4.)
TBL 6−2−3
Air Force Rescue Coordination Center
48 Contiguous States
Air Force Rescue Coordination Center
Tyndall AFB, Florida Phone
Commercial 850−283−5955
WATS 800−851−3051
DSN 523−5955
TBL 6−2−4
Air Command Rescue Coordination Center
Alaska
Alaskan Air Command Rescue
Coordination Center
Elmendorf AFB, Alaska Phone
Commercial 907−428−7230
800−420−7230
(outside Anchorage)
DSN 317−551−7230
e. Joint Rescue Coordination Center.
(See TBL 6 −2−5.)
TBL 6−2−5
Joint Rescue Coordination Center
Hawaii
Honolulu Joint Rescue Coordination Center
HQ 14th CG District
HonoluluPhone
Commercial 808−541−2500
DSN 448−0301f. Emergency and Overdue Aircraft.
1.ARTCCs and FSSs will alert the SAR system
when information is received from any source that an
aircraft is in difficulty, overdue, or missing.
(a)Radar facilities providing radar flight
following or advisories consider the loss of radar and
radios, without service termination notice, to be a
possible emergency. Pilots receiving VFR services
from radar facilities should be aware that SAR maybe initiated under these circumstances.
(b)A filed flight plan is the most timely and
effective indicator that an aircraft is overdue. Flight
plan information is invaluable to SAR forces for
search planning and executing search efforts.
2.Prior to departure on every flight, local or
otherwise, someone at the departure point should beadvised of your destination and route of flight if other
than direct. Search efforts are often wasted and rescue
is often delayed because of pilots who thoughtlessly
takeoff without telling anyone where they are going.
File a flight plan for your safety.
3.According to the National Search and Rescue
Plan, “The life expectancy of an injured survivor
decreases as much as 80 percent during the first
24 hours, while the chances of survival of uninjuredsurvivors rapidly diminishes after the first 3 days.”
4.An Air Force Review of 325 SAR missions
conducted during a 23 −month period revealed that
“Time works against people who experience a
distress but are not on a flight plan, since 36 hours
normally pass before family concern initiates an(alert).”
g. VFR Search and Rescue Protection.
1.To receive this valuable protection, file a VFR
or DVFR Flight Plan with an FAA FSS. For
maximum protection, file only to the point of first
intended landing, and refile for each leg to final
destination. When a lengthy flight plan is filed, with
several stops en route and an ETE to final destination,
a mishap could occur on any leg, and unless otherinformation is received, it is probable that no one
would start looking for you until 30 minutes after
your ETA at your final destination.
2.If you land at a location other than the
intended destination, report the landing to the nearest
FAA FSS and advise them of your original
destination.
AIM 10/12/17
6−2−6 Emergency Services Available to Pilots3.If you land en route and are delayed more than
30 minutes, report this information to the nearest FSS
and give them your original destination.
4.If your ETE changes by 30 minutes or more,
report a new ETA to the nearest FSS and give them
your original destination. Remember that if you fail
to respond within one-half hour after your ETA at
final destination, a search will be started to locate you.
5.It is important that you close your flight plan
IMMEDIATELY AFTER ARRIVAL AT YOUR FINAL
DESTINATION WITH THE FSS DESIGNATED
WHEN YOUR FLIGHT PLAN WAS FILED. The pilot
is responsible for closure of a VFR or DVFR flight
plan; they are not closed automatically. This will
prevent needless search efforts.
6.The rapidity of rescue on land or water will
depend on how accurately your position may be
determined. If a flight plan has been followed and
your position is on course, rescue will be expedited.
h. Survival Equipment.
1.For flight over uninhabited land areas, it is
wise to take and know how to use survival equipment
for the type of climate and terrain.
2.If a forced landing occurs at sea, chances for
survival are governed by the degree of crew
proficiency in emergency procedures and by the
availability and effectiveness of water survivalequipment.
i. Body Signal Illustrations.
1.If you are forced down and are able to attract
the attention of the pilot of a rescue airplane, the bodysignals illustrated on these pages can be used to
transmit messages to the pilot circling over your
location.
2.Stand in the open when you make the signals.
3.Be sure the background, as seen from the air,
is not confusing.
4.Go through the motions slowly and repeat
each signal until you are positive that the pilot
understands you.
j. Observance of Downed Aircraft.
1.Determine if crash is marked with a yellow
cross; if so, the crash has already been reported and
identified.
2.If possible, determine type and number of
aircraft and whether there is evidence of survivors.
3.Fix the position of the crash as accurately as
possible with reference to a navigational aid. Ifpossible, provide geographic or physical description
of the area to aid ground search parties.
4.Transmit the information to the nearest FAA
or other appropriate radio facility.
5.If circumstances permit, orbit the scene to
guide in other assisting units until their arrival or until
you are relieved by another aircraft.
6.Immediately after landing, make a complete
report to the nearest FAA facility, or Air Force orCoast Guard Rescue Coordination Center. The report
can be made by a long distance collect telephone call.
AIM 10/12/17
6−2−7 Emergency Services Available to PilotsFIG 6−2−1
Ground−Air Visual Code for Use by Survivors
V
X
N
YNO.NO. MESSAGEMESSAGE CODE SYMBOLCODE SYMBOL
1 Require assistanceRequire assistance
Require medical assistanceRequire medical assistance
No or NegativeNo or Negative
Yes or AffirmativeYes or Affirmative
Proceeding in this directionProceeding in this direction
IF IN DOUBT, USE INTERNATIONAL SYMBOLIF IN DOUBT, USE INTERNATIONAL SYMBOL
INSTRUCTIONSINSTRUCTIONS2
S O S
1. Lay out symbols by using strips of fabric or parachutes, pieces of wood, stones, or any available material.
2. Provide as much color contrast as possible between material used for symbols and background against which symbols are expos ed.
3. Symbols should be at least 10 feet high or larger. Care should be taken to lay out symbols exactly as shown.4. In addition to using symbols, every effort is to be made to attract attention by means of radio, flares, smoke, or other av ailable means.
5. On snow covered ground, signals can be made by dragging, shoveling or tramping. Depressed areas forming symbols will
appear black from the air.
6. Pilot should acknowledge message by rocking wings from side to side.
FIG 6−2−2
Ground−Air Visual C ode for use by Ground Search Parties
L L L
L L
X X
N NNO.NO. MESSAGEMESSAGE CODE SYMBOLCODE SYMBOL
567Operation completed.Operation completed.
We have found all personnel.We have found all personnel.
We have found only some personnel.We have found only some personnel.
We are not able to continue.
Returning to base.We are not able to continue.
Returning to base.
Have divided into two groups.Each proceeding in direction indicated.Have divided into two groups.
Each proceeding in direction indicated.
Information received that aircraft is in this direction.Information received that aircraft is in this direction.
Nothing found. Will continue search.Nothing found. Will continue search.
Note: These visual signals have been accepted for international use and appear in Annex 12 to the Convention on International
Civil Aviation.
AIM 10/12/17
6−2−8 Emergency Services Available to PilotsFIG 6−2−3
Urgent Medical Assistance
NEED MEDICAL
ASSISTANCE-URGENT
Used only when life is at stakeNEED MEDICAL
ASSISTANCE-URGENT
Used only when life is at stake
FIG 6−2−4
All OK
ALL OK-DO NOT WAIT
Wave one arm overheadALL OK-DO NOT WAIT
Wave one arm overheadFIG 6−2−5
Short Delay
CAN PROCEED SHORTLY
WAIT IF PRACTICABLE
One arm horizontalCAN PROCEED SHORTLY
WAIT IF PRACTICABLE
One arm horizontal
FIG 6−2−6
Long Delay
NEED MECHANICAL HELP
OR PARTS - LONG DELAY
Both arms horizontalNEED MECHANICAL HELP
OR PARTS - LONG DELAY
Both arms horizontal
AIM 10/12/17
6−2−9 Emergency Services Available to PilotsFIG 6−2−7
Drop Message
Make throwing motion
FIG 6−2−8
Receiver Operates
OUR RECEIVER IS
OPERATING
Cup hands over earsOUR RECEIVER IS
OPERATING
Cup hands over earsFIG 6−2−9
Do Not Land Here
DO NOT ATTEMPT
TO LAND HERE
Both arms waved across faceDO NOT ATTEMPT
TO LAND HERE
Both arms waved across face
FIG 6−2−10
Land Here
LAND HERE
Both arms forward horizontally,
squatting and point in direction
of landing - RepeatLAND HERE
Both arms forward horizontally,
squatting and point in direction
of landing - Repeat
AIM 10/12/17
6−2−10 Emergency Services Available to PilotsFIG 6−2−11
Negative (Ground)
NEGATIVE (NO)
White cloth waved horizontallyNEGATIVE (NO)
White cloth waved horizontally
FIG 6−2−12
Affirmative (Ground)
AFFIRMATIVE (YES)
White cloth waved verticallyAFFIRMATIVE (YES)
White cloth waved verticallyFIG 6−2−13
Pick Us Up
PICK US UP-
PLANE ABANDONED
Both arms verticalPICK US UP-
PLANE ABANDONED
Both arms vertical
FIG 6−2−14
Affirmative (Aircraft)
Affirmative reply from aircraft:
AFFIRMATIVE (YES)
Dip nose of plane several times
AIM 10/12/17
6−2−11 Emergency Services Available to PilotsFIG 6−2−15
Negative (Aircraft)
NEGATIVE (NO)
Fishtail planeNEGATIVE (NO)
Fishtail planeNegative reply from aircraft:Negative reply from aircraft:FIG 6−2−16
Message received and understood (Aircraft)
Message received and understood by aircraft:
Day or moonlight - Rocking wingsNight - Green flashed from signal lampMessage received and understood by aircraft:
Day or moonlight - Rocking wings
Night - Green flashed from signal lamp
FIG 6−2−17
Message received and NOT understood (Aircraft)
Message received and NOT understood by aircraft:
Day or moonlight - Making a complete right-hand circleNight-Red flashes from signal lamp.Message received and NOT understood by aircraft:
Day or moonlight - Making a complete right-hand circle
Night-Red flashes from signal lamp.
AIM 10/12/17
6−3−1 Distress and Urgency ProceduresSection 3. Distress and Urgency Procedures
6−3−1. Distress and Urgency
Communications
a.A pilot who encounters a distress or urgency
condition can obtain assistance simply by contacting
the air traffic facility or other agency in whose area of
responsibility the aircraft is operating, stating thenature of the difficulty, pilot’s intentions and
assistance desired. Distress and urgency communica-
tions procedures are prescribed by the InternationalCivil Aviation Organization (ICAO), however, and
have decided advantages over the informal procedure
described above.
b.Distress and urgency communications proce-
dures discussed in the following paragraphs relate to
the use of air ground voice communications.
c.The initial communication, and if considered
necessary, any subsequent transmissions by an
aircraft in distress should begin with the signal
MAYDAY , preferably repeated three times. Thesignal PAN −PAN should be used in the same manner
for an urgency condition.
d.Distress communications have absolute priority
over all other communications, and the word
MAYDAY commands radio silence on the frequency
in use. Urgency communications have priority over
all other communications except distress, and the
word PAN −PAN warns other stations not to interfere
with urgency transmissions.
e.Normally, the station addressed will be the
air traffic facility or other agency providing air traffic
services, on the frequency in use at the time. If the
pilot is not communicating and receiving services,the station to be called will normally be the air traffic
facility or other agency in whose area of responsibil-
ity the aircraft is operating, on the appropriateassigned frequency. If the station addressed does not
respond, or if time or the situation dictates, the
distress or urgency message may be broadcast, or a
collect call may be used, addressing “Any Station
(Tower)(Radio)(Radar).”
f.The station addressed should immediately
acknowledge a distress or urgency message, provide
assistance, coordinate and direct the activities of
assisting facilities, and alert the appropriate searchand rescue coordinator if warranted. Responsibility
will be transferred to another station only if better
handling will result.
g.All other stations, aircraft and ground, will
continue to listen until it is evident that assistance is
being provided. If any station becomes aware that the
station being called either has not received a distress
or urgency
message, or cannot communicate with the
aircraft in difficulty, it will attempt to contact theaircraft and provide assistance.
h.Although the frequency in use or other
frequencies assigned by ATC are preferable, thefollowing emergency frequencies can be used for
distress or urgency communications, if necessary or
desirable:
121.5 MHz and 243.0 MHz. Both have a range
generally limited to line of sight. 121.5 MHz is
guarded by direction finding stations and some
military and civil aircraft. 243.0 MHz is guarded bymilitary aircraft. Both 121.5 MHz and 243.0 MHz are
guarded by military towers, most civil towers, and
radar facilities. Normally ARTCC emergency
frequency capability does not extend to radar
coverage limits. If an ARTCC does not respond when
called on 121.5 MHz or 243.0 MHz, call the nearest
tower.
6−3−2. Obtaining Emergency Assistance
a.A pilot in any distress or urgency condition
should immediately take the following action, not
necessarily in the order listed, to obtain assistance:
1.Climb, if possible, for improved communica-
tions, and better radar and direction finding detection.
However, it must be understood that unauthorizedclimb or descent under IFR conditions within
controlled airspace is prohibited, except as permitted
by 14 CFR Section 91.3(b).
2.If equipped with a radar beacon transponder
(civil) or IFF/SIF (military):
(a)Continue squawking assigned Mode A/3
discrete code/VFR code and Mode C altitudeencoding when in radio contact with an air traffic
facility or other agency providing air traffic services,
unless instructed to do otherwise.
AIM 10/12/17
6−3−2 Distress and Urgency Procedures(b)If unable to immediately establish com-
munications with an air traffic facility/agency,
squawk Mode A/3, Code 7700/Emergency and
Mode C.
3.Transmit a distress or urgency message
consisting of as many as necessary of the following
elements, preferably in the order listed:
(a)If distress, MAYDAY , MAYDAY , MAY −
DAY; if urgency , PAN−PAN, PAN −PAN, PAN −PAN.
(b)Name of station addressed.
(c)Aircraft identification and type.
(d)Nature of distress or urgency .
(e)Weather.
(f)Pilots intentions and request.
(g)Present position, and heading; or if lost,
last known position, time, and heading since thatposition.
(h)Altitude or flight level.
(i)Fuel remaining in minutes.
(j)Number of people on board.
(k)Any other useful information.
REFERENCE −
Pilot/Controller Glossary Term − Fuel Remaining.
b.After establishing radio contact, comply with
advice and instructions received. Cooperate. Do not
hesitate to ask questions or clarify instructions whenyou do not understand or if you cannot comply with
clearance. Assist the ground station to control
communications on the frequency in use. Silence
interfering radio stations. Do not change frequency or
change to another ground station unless absolutelynecessary. If you do, advise the ground station of the
new frequency and station name prior to the change,
transmitting in the blind if necessary. If two −way
communications cannot be established on the new
frequency, return immediately to the frequency orstation where two −way communications last existed.
c.When in a distress condition with bailout, crash
landing or ditching imminent, take the following
additional actions to assist search and rescue units:
1.Time and circumstances permitting, transmit
as many as necessary of the message elements in
subparagraph a3 above, and any of the following that
you think might be helpful:
(a)ELT status.
(b)Visible landmarks.
(c)Aircraft color.
(d)Number of persons on board.
(e)Emergency equipment on board.
2.Actuate your ELT if the installation permits.
3.For bailout, and for crash landing or ditching
if risk of fire is not a consideration, set your radio for
continuous transmission.
4.If it becomes necessary to ditch, make every
effort to ditch near a surface vessel. If time permits,
an FAA facility should be able to get the position of
the nearest commercial or Coast Guard vessel from a
Coast Guard Rescue Coordination Center.
5.After a crash landing, unless you have good
reason to believe that you will not be located by
search aircraft or ground teams, it is best to remain
with your aircraft and prepare means for signaling
search aircraft.
AIM 10/12/17
6−3−3 Distress and Urgency Procedures6−3−3. Ditching Procedures
FIG 6−3−1
Single Swell (15 knot wind)
SWELLSWELL
DITCHING
HEADING
WIND
FIG 6−3−2
Double Swell (15 knot wind)
PRIMARY
SWELLPRIMARY
SWELL
SECONDARY
SWELLSECONDARYSWELLHEADINGWIND
DITCHINGFIG 6−3−3
Double Swell (30 knot wind)
PRIMARY
SWELLPRIMARY
SWELL
SECONDARY
SWELLSECONDARYSWELL
WINDDITCHING
HEADING
FIG 6−3−4
(50 knot wind)
SWELLSWELL
WINDWIND
Aircraft with low landing speeds - land into the wind.
Aircraft with high landing speeds - choose compromise
heading between wind and swell.
Both - land on back side of swell.
AIM 10/12/17
6−3−4 Distress and Urgency ProceduresFIG 6−3−5
Wind−Swell−Ditch Heading
GOOD
GOOD !!
BACK SIDEPOOR!!!
FACEGOODFAIRBESTBESTDIRECTION OF
SWELL MOVEMENT
Landing parallel to the major swell
Landing on the face and back of swell
a.A successful aircraft ditching is dependent on
three primary factors. In order of importance they are:
1. Sea conditions and wind.
2. Type of aircraft.
3. Skill and technique of pilot.
b. Common oceanographic terminology.
1. Sea. The condition of the surface that is the
result of both waves and swells.
2. Wave (or Chop). The condition of the
surface caused by the local winds.
3. Swell. The condition of the surface which
has been caused by a distance disturbance.
4. Swell Face. The side of the swell toward the
observer. The backside is the side away from the
observer. These definitions apply regardless of the
direction of swell movement.
5. Primary Swell. The swell system having the
greatest height from trough to crest.6. Secondary Swells. Those swell systems of
less height than the primary swell.
7. Fetch. The distance the waves have been
driven by a wind blowing in a constant direction,without obstruction.
8. Swell Period. The time interval between the
passage of two successive crests at the same spot in
the water, measured in seconds.
9. Swell Velocity. The speed and direction of
the swell with relation to a fixed reference point,
measured in knots. There is little movement of water
in the horizontal direction. Swells move primarily ina vertical motion, similar to the motion observed
when shaking out a carpet.
10. Swell Direction. The direction from which
a swell is moving. This direction is not necessarily theresult of the wind present at the scene. The swell may
be moving into or across the local wind. Swells, once
set in motion, tend to maintain their original directionfor as long as they continue in deep water, regardless
of changes in wind direction.
AIM 10/12/17
6−3−5 Distress and Urgency Procedures11. Swell Height. The height between crest
and trough, measured in feet. The vast majority of
ocean swells are lower than 12 to 15 feet, and swells
over 25 feet are not common at any spot on the
oceans. Successive swells may dif fer considerably in
height.
c.In order to select a good heading when ditching
an aircraft, a basic evaluation of the sea is required.
Selection of a good ditching heading may well
minimize damage and could save your life. It can beextremely dangerous to land into the wind without
regard to sea conditions; the swell system, or systems,
must be taken into consideration. Remember oneaxiom− AVOID THE FACE OF A SWELL.
1.In ditching parallel to the swell, it makes little
difference whether touchdown is on the top of the
crest or in the trough. It is preferable, however, to land
on the top or back side of the swell, if possible. After
determining which heading (and its reciprocal) will
parallel the swell, select the heading with the mostinto the wind component.
2.If only one swell system exists, the problem
is relatively simple −even with a high, fast system.
Unfortunately, most cases involve two or more swell
systems running in different directions. With more
than one system present, the sea presents a confused
appearance. One of the most difficult situationsoccurs when two swell systems are at right angles.
For example, if one system is eight feet high, and the
other three feet, plan to land parallel to the primarysystem, and on the down swell of the secondary
system. If both systems are of equal height, a
compromise may be advisable −select an intermediate
heading at 45 degrees down swell to both systems.
When landing down a secondary swell, attempt to
touch down on the back side, not on the face of theswell.
3.If the swell system is formidable, it is
considered advisable, in landplanes, to accept more
crosswind in order to avoid landing directly into theswell.
4.The secondary swell system is often from the
same direction as the wind. Here, the landing may be
made parallel to the primary system, with the wind
and secondary system at an angle. There is a choiceto two directions paralleling the primary system. One
direction is downwind and down the secondary swell,
and the other is into the wind and into the secondaryswell, the choice will depend on the velocity of the
wind versus the velocity and height of the secondary
swell.
d.The simplest method of estimating the wind
direction and velocity is to examine the windstreaks
on the water. These appear as long streaks up and
down wind. Some persons may have difficulty
determining wind direction after seeing the streaks on
the water. Whitecaps fall forward with the wind butare overrun by the waves thus producing the illusion
that the foam is sliding backward. Knowing this, and
by observing the direction of the streaks, the winddirection is easily determined. Wind velocity can be
estimated by noting the appearance of the whitecaps,
foam and wind streaks.
1.The behavior of the aircraft on making
contact with the water will vary within wide limits
according to the state of the sea. If landed parallel to
a single swell system, the behavior of the aircraft mayapproximate that to be expected on a smooth sea. If
landed into a heavy swell or into a confused sea, the
deceleration forces may be extremely great −resulting
in breaking up of the aircraft. Within certain limits,
the pilot is able to minimize these forces by proper sea
evaluation and selection of ditching heading.
2.When on final approach the pilot should look
ahead and observe the surface of the sea. There may
be shadows and whitecaps −signs of large seas.
Shadows and whitecaps close together indicate short
and rough seas. Touchdown in these areas is to be
avoided. Select and touchdown in any area (only
about 500 feet is needed) where the shadows andwhitecaps are not so numerous.
3.Touchdown should be at the l owest speed and
rate of descent which permit safe handling and
optimum nose up attitude on impact. Once firstimpact has been made, there is often little the pilot can
do to control a landplane.
e.Once preditching preparations are completed,
the pilot should turn to the ditching heading andcommence let −down. The aircraft should be flown
low over the water, and slowed down until ten knots
or so above stall. At this point, additional powershould be used to overcome the increased drag caused
by the nose up attitude. When a smooth stretch of
water appears ahead, cut power, and touchdown at the
best recommended speed as fully stalled as possible.
By cutting power when approaching a relatively
smooth area, the pilot will prevent overshooting and
AIM 10/12/17
6−3−6 Distress and Urgency Procedureswill touchdown with less chance of planing off into
a second uncontrolled landing. Most experienced
seaplane pilots prefer to make contact with the water
in a semi −stalled attitude, cutting power as the tail
makes contact. This technique eliminates the chanceof misjudging altitude with a resultant heavy drop in
a fully stalled condition. Care must be taken not to
drop the aircraft from too high altitude or to balloondue to excessive speed. The altitude above water
depends on the aircraft. Over glassy smooth water, or
at night without sufficient light, it is very easy, foreven the most experienced pilots to misjudge altitude
by 50 feet or more. Under such conditions, carry
enough power to maintain nine to twelve degreesnose up attitude, and 10 to 20 percent over stalling
speed until contact is made with the water. The proper
use of power on the approach is of great importance.If power is available on one side only, a little power
should be used to flatten the approach; however, the
engine should not be used to such an extent that theaircraft cannot be turned against the good engines
right down to the stall with a margin of rudder
movement available. When near the stall, suddenapplication of excessive unbalanced power may
result in loss of directional control. If power is
available on one side only, a slightly higher than
normal glide approach speed should be used. This
will ensure good control and some margin of speedafter leveling off without excessive use of power. The
use of power in ditching is so important that when it
is certain that the coast cannot be reached, the pilotshould, if possible, ditch before fuel is exhausted. The
use of power in a night or instrument ditching is far
more essential than under daylight contactconditions.
1.If no power is available, a greater than normal
approach speed should be used down to the flare −out.
This speed margin will allow the glide to be broken
early and more gradually, thereby giving the pilot
time and distance to feel for the surface − decreasing
the possibility of stalling high or flying into the water.
When landing parallel to a swell system, little
difference is noted between landing on top of a crest
or in the trough. If the wings of aircraft are trimmed
to the surface of the sea rather than the horizon, thereis little need to worry about a wing hitting a swell
crest. The actual slope of a swell is very gradual. If
forced to land into a swell, touchdown should bemade just after passage of the crest. If contact is made
on the face of the swell, the aircraft may be swamped
or thrown violently into the air, dropping heavily into
the next swell. If control surfaces remain intact, the
pilot should attempt to maintain the proper noseabove the horizon attitude by rapid and positive use
of the controls.
f. After Touchdown. In most cases drift, caused
by crosswind can be ignored; the forces acting on theaircraft after touchdown are of such magnitude that
drift will be only a secondary consideration. If the
aircraft is under good control, the “crab” may bekicked out with rudder just prior to touchdown. This
is more important with high wing aircraft, for they are
laterally unstable on the water in a crosswind and may
roll to the side in ditching.
REFERENCE −
This information has been extracted from Appendix H of the “National
Search and Rescue Manual.”
6−3−4. Special Emergency (Air Piracy)
a.A special emergency is a condition of air piracy,
or other hostile act by a person(s) aboard an aircraft,
which threatens the safety of the aircraft or its
passengers.
b.The pilot of an aircraft reporting a special
emergency condition should:
1.If circumstances permit, apply distress or
urgency radio−telephony procedures. Include the
details of the special emergency.
REFERENCE −
AIM, Paragraph 6 −3−1 , Distress and Urgency Communications
2.If circumstances do not permit the use of
prescribed distress or urgency procedures, transmit:
(a)On the air/ground frequency in use at the
time.
(b)As many as possible of the following
elements spoken distinctly and in the following order:
(1)Name of the station addressed (time and
circumstances permitting).
(2)The identification of the aircraft and
present position.
(3)The nature of the special emergency
condition and pilot intentions (circumstances
permitting).
AIM 10/12/17
6−3−7 Distress and Urgency Procedures(4)If unable to provide this information,
use code words and/or transponder as follows:
Spoken Words
TRANSPONDER SEVEN FIVE ZERO ZERO
MeaningI am being hijacked/forced to a new destination
Transponder SettingMode 3/A, Code 7500
NOTE−
Code 7500 will never be assigned by ATC without priornotification from the pilot that the aircraft is beingsubjected to unlawful interference. The pilot should refuse
the assignment of Code 7500 in any other situation and
inform the controller accordingly. Code 7500 will trigger
the special emergency indicator in all radar ATC facilities.
c.Air traffic controllers will acknowledge and
confirm receipt of transponder Code 7500 by asking
the pilot to verify it. If the aircraft is not beingsubjected to unlawful interference, the pilot should
respond to the query by broadcasting in the clear that
the aircraft is not being subjected to unlawfulinterference. Upon receipt of this information, the
controller will request the pilot to verify the code
selection depicted in the code selector windows in the
transponder control panel and change the code to the
appropriate setting. If the pilot replies in the
affirmative or does not reply, the controller will notask further questions but will flight follow, respond to
pilot requests and notify appropriate authorities.
d.If it is possible to do so without jeopardizing the
safety of the flight, the pilot of a hijacked passengeraircraft, after departing from the cleared routing over
which the aircraft was operating, will attempt to do
one or more of the following things, insofar as
circumstances may permit:1.Maintain a true airspeed of no more than
400 knots, and preferably an altitude of between
10,000 and 25,000 feet.
2.Fly a course toward the destination which the
hijacker has announced.
e.If these procedures result in either radio contact
or air intercept, the pilot will attempt to comply with
any instructions received which may direct the
aircraft to an appropriate landing field or alter the
aircraft’s flight path off its current course, away from
protected airspace.
6−3−5. Fuel Dumping
a.Should it become necessary to dump fuel, the
pilot should immediately advise ATC. Upon receipt
of information that an aircraft will dump fuel, ATC
will broadcast or cause to be broadcast immediatelyand every 3 minutes thereafter the following on
appropriate ATC and FSS radio frequencies:
EXAMPLE −
Attention all aircraft − fuel dumping in progress over −
(location) at (altitude) by (type air craft) (flight direction).
b.Upon receipt of such a broadcast, pilots of
aircraft affected, which are not on IFR flight plans or
special VFR clearances, should clear the area
specified in the advisory. Aircraft on IFR flight plans
or special VFR clearances will be provided specific
separation by ATC. At the termination of the fuel
dumping operation, pilots should advise ATC. Uponreceipt of such information, ATC will issue, on the
appropriate frequencies, the following:
EXAMPLE −
ATTENTION ALL AIRCRAFT − FUEL DUMPING BY −
(type aircr aft) − TERMINA TED.
AIM 10/12/17
6−4−1 Two-way Radio Communications FailureSection 4. Two-way Radio Communications Failure
6−4−1. Two-way Radio Communications
Failure
a.It is virtually impossible to provide regulations
and procedures applicable to all possible situations
associated with two-way radio communicationsfailure. During two-way radio communications
failure, when confronted by a situation not covered in
the regulation, pilots are expected to exercise goodjudgment in whatever action they elect to take.
Should the situation so dictate they should not be
reluctant to use the emergency action contained in14 CFR Section 91.3(b).
b.Whether two-way communications failure
constitutes an emergency depends on the circum-
stances, and in any event, it is a determination made
by the pilot. 14 CFR Section 91.3(b) authorizes a
pilot to deviate from any rule in Subparts A and B to
the extent required to meet an emergency.
c.In the event of two-way radio communications
failure, A TC service will be provided on the basis that
the pilot is operating in accordance with 14 CFR
Section 91.185. A pilot experiencing two-way
communications failure should (unless emergencyauthority is exercised) comply with 14 CFR
Section 91.185 quoted below:
1. General. Unless otherwise authorized by
ATC, each pilot who has two-way radio communica-
tions failure when operating under IFR must complywith the rules of this section.
2. VFR conditions. If the failure occurs in
VFR conditions, or if VFR conditions are encoun-
tered after the failure, each pilot must continue the
flight under VFR and land as soon as practicable.
NOTE−
This procedure also applies when two-way radio failure
occurs while operating in Class A airspace. The primary
objective of this provision in 14 CFR Section 91.185 is to
preclude extended IFR operation by these aircraft within
the ATC system. Pilots should recognize that operationunder these conditions may unnecessarily as well asadversely affect other users of the airspace, since ATC may
be required to reroute or delay other users in order to
protect the failure aircraft. However , it is not intended that
the requirement to “land as soon as practicable” beconstrued to mean “as soon as possible.” Pilots retain the
prerogative of exercising their best judgment and are notrequired to land at an unauthorized airport, at an airport
unsuitable for the type of aircraft flown, or to land onlyminutes short of their intended destination.
3. IFR conditions. If the failure occurs in IFR
conditions, or if subparagraph 2 above cannot be
complied with, each pilot must continue the flight
according to the following:
(a) Route.
(1)By the route assigned in the last ATC
clearance received;
(2)If being radar vectored, by the direct
route from the point of radio failure to the fix, route,
or airway specified in the vector clearance;
(3)In the absence of an assigned route, by
the route that ATC has advised may be expected in afurther clearance; or
(4)In the absence of an assigned route or a
route that ATC has advised may be expected in a
further clearance by the route filed in the flight plan.
(b) Altitude. At the HIGHEST of the
following altitudes or flight levels FOR THE ROUTE
SEGMENT BEING FLOWN:
(1)The altitude or flight level assigned in
the last ATC clearance received;
(2)The minimum altitude (converted, if
appropriate, to minimum flight level as prescribed in
14 CFR Section 91.121(c)) for IFR operations; or
(3)The altitude or flight level ATC has
advised may be expected in a further clearance.
NOTE−
The intent of the rule is that a pilot who has experienced
two-way radio failure should select the appropriate
altitude for the particular route segment being flown andmake the necessary altitude adjustments for subsequentroute segments. If the pilot received an “expect furtherclearance” containing a higher altitude to expect at a
specified time or fix, maintain the highest of the following
altitudes until that time/fix:
(1) the last assigned altitude; or
(2) the minimum altitude/flight level for IFR
operations.
Upon reaching the time/fix specified, the pilot should
commence climbing to the altitude advised to expect. If the
AIM 10/12/17
6−4−2 Two-way Radio Communications Failureradio failure occurs after the time/fix specified, the altitude
to be expected is not applicable and the pilot shouldmaintain an altitude consistent with 1 or 2 above. If thepilot receives an “expect further clearance” containing a
lower altitude, the pilot should maintain the highest of 1 or
2 above until that time/fix specified in subparagraph (c)Leave clearance limit, below.
EXAMPLE −
1.A pilot experiencing two-way radio failure at an
assigned altitude of 7,000 feet is cleared along a direct
route which will r equire a climb to a minimum IFR altitude
of 9,000 feet, should climb to reach 9,000 feet at the time
or place where it becomes necessary (see 14 CFR
Section 91.177(b)). Later while proceeding along anairway with an MEA of 5,000 feet, the pilot would descend
to 7,000 feet (the last assigned altitude), because that
altitude is higher than the MEA.
2.A pilot experiencing two-way radio failure while being
progressively descended to lower altitudes to begin an
approach is assigned 2,700 feet until cr ossing the VOR and
then cleared for the approach. The MOCA along the airway
is 2,700 feet and MEA is 4,000 feet. The aircraft is within
22 NM of the VOR. The pilot should remain at 2,700 feet
until crossing the VOR because that altitude is theminimum IFR altitude for the route segment being flown.
3.The MEA between a and b: 5,000 feet. The MEA
between b and c: 5,000 feet. The MEA between c and d:11,000 feet. The MEA between d and e: 7,000 feet. A pilothad been cleared via a, b, c, d, to e. While flying between
a and b the assigned altitude was 6,000 feet and the pilot
was told to expect a clearance to 8,000 feet at b. Prior toreceiving the higher altitude assignment, the pilot
experienced two-way failure. The pilot would maintain
6,000 to b, then climb to 8,000 feet (the altitude advised to
expect). The pilot would maintain 8,000 feet, then climb to
11,000 at c, or prior to c if necessary to comply with an
MCA at c. (14 CFR Section 91.177(b).) Upon reaching d,the pilot would descend to 8,000 feet (even though the MEA
was 7,000 feet), as 8,000 was the highest of the altitude
situations stated in the rule (14 CFR Section 91.185).
(c) Leave clearance limit.
(1)When the clearance limit is a fix from
which an approach begins, commence descent or
descent and approach as close as possible to the
expect further clearance time if one has beenreceived, or if one has not been received, as close as
possible to the Estimated Time of Arrival (ETA) ascalculated from the filed or amended (with ATC)
Estimated Time En Route (ETE).
(2)If the clearance limit is not a fix from
which an approach begins, leave the clearance limitat the expect further clearance time if one has been
received, or if none has been received, upon arrival
over the clearance limit, and proceed to a fix from
which an approach begins and commence descent or
descent and approach as close as possible to theestimated time of arrival as calculated from the filed
or amended (with ATC) estimated time en route.
6−4−2. Transponder Operation During
Two-way Communications Failure
a.If an aircraft with a coded radar beacon
transponder experiences a loss of two-way radio
capability, the pilot should adjust the transponder toreply on Mode A/3, Code 7600.
b.The pilot should understand that the aircraft
may not be in an area of radar coverage.
6−4−3. Reestablishing Radio Contact
a.In addition to monitoring the NA V AID voice
feature, the pilot should attempt to reestablishcommunications by attempting contact:
1.On the previously assigned frequency; or
2.With an FSS or *ARINC.
b.If communications are established with an FSS
or ARINC, the pilot should advise that radio
communications on the previously assigned frequen-
cy has been lost giving the aircraft’s position, altitude,
last assigned frequency and then request further
clearance from the controlling facility. The preceding
does not preclude the use of 121.5 MHz. There is no
priority on which action should be attempted first. If
the capability exists, do all at the same time.
NOTE−
*Aeronautical Radio/Incorporated (ARINC) is a commer-
cial communications corporation which designs,constructs, operates, leases or otherwise engages in radio
activities serving the aviation community. ARINC has thecapability of relaying information to/from ATC facilities
throughout the country.
AIM 10/12/17
6−5−1 Aircraft Rescue and Fire Fighting CommunicationsSection 5. Aircraft Rescue and
Fire Fighting Communications
6−5−1. Discrete Emergency Frequency
a.Direct contact between an emergency aircraft
flight crew, Aircraft Rescue and Fire FightingIncident Commander (ARFF IC), and the Airport
Traffic Control Tower (ATCT), is possible on an
aeronautical radio frequency (Discrete EmergencyFrequency [DEF]), designated by Air Traffic
Control (ATC) from the operational frequencies
assigned to that facility.
b.Emergency aircraft at airports without an
ATCT, (or when the A TCT is closed), may contact the
ARFF IC (if ARFF service is provided), on the
Common Traffic Advisory Frequency (CTAF)
published for the airport or the civil emergencyfrequency 121.5 MHz.6−5−2. Radio Call Signs
Preferred radio call sign for the ARFF IC is
“(location/facility) Command ” when communica-
ting with the flight crew and the FAA ATCT.
EXAMPLE −
LAX Command.Washington Command.
6−5−3. ARFF Emergency Hand Signals
In the event that electronic communications cannot
be maintained between the ARFF IC and the flightcrew, standard emer gency hand signals as depicted in
FIG 6−5−1 through FIG 6−5−3 should be used. These
hand signals should be known and understood by allcockpit and cabin aircrew, and all ARFF firefighters.
FIG 6−5−1
Recommend Evacuation
FIG 6−5−2
Recommend Stop
AIM 10/12/17
6−5−2 Aircraft Rescue and Fire Fighting CommunicationsFIG 6−5−3
Emergency Contained
AIM 10/12/17
7−1−1 MeteorologyChapter 7. Safety of Flight
Section 1. Meteorology
7−1−1. National Weather Service Aviation
Weather Service Program
a.Weather service to aviation is a joint ef fort of the
National Oceanic and Atmospheric Administration
(NOAA), the National Weather Service (NWS), the
Federal Aviation Administration (FAA), Department
of Defense, and various private sector aviation
weather service providers. Requirements for all
aviation weather products originate from the FAA,which is the Meteorological Authority for the U.S.
b.NWS meteorologists are assigned to all air
route traffic control centers (ARTCC) as part of theCenter W eather Service Units (CWSU) as well as the
Air Traffic Control System Command Center
(ATCSCC). These meteorologists provide special-ized briefings as well as tailored forecasts to support
the needs of the FAA and other users of the NAS.
c.Aviation Products
1.The NWS maintains an extensive surface,
upper air, and radar weather observing program; and
a nationwide aviation weather forecasting service.
2.Airport observations (METAR and SPECI)
supported by the NWS are provided by automated
observing systems.
3.Terminal Aerodrome Forecasts (TAF) are
prepared by 123 NWS Weather Forecast Offices
(WFOs) for over 700 airports. These forecasts are
valid for 24 or 30 hours and amended as required.
4.Inflight aviation advisories (for example,
Significant Meteorological Information (SIGMETs)
and Airmen’s Meteorological Information (AIR-METs)) are issued by three NWS Meteorological
Watch Offices; the Aviation Weather Center (AWC)
in Kansas City, MO, the Alaska Aviation WeatherUnit (AAWU) in Anchorage, AK, and the WFO in
Honolulu, HI. Both the AWC and the AAWU issue
area forecasts (FA) for selected areas. In addition,NWS meteorologists assigned to most ARTCCs as
part of the Center Weather Service Unit (CWSU)
provide Center Weather Advisories (CWAs) andgather weather information to support the needs of
the FAA and other users of the system.
5.Several NWS National Centers for Environ-
mental Production (NCEP) provide aviation specific
weather forecasts, or select public forecasts which are
of interest to pilots and operators.
(a)The Aviation Weather Center (AWC)
displays a variety of domestic and internationalaviation forecast products over the Internet at
aviationweather.gov.
(b)The NCEP Central Operations (NCO) is
responsible for the operation of many numerical
weather prediction models, including those which
produce the many wind and temperature aloft
forecasts.
(c)The Storm Prediction Center (SPC) issues
tornado and severe weather watches along with other
guidance forecasts.
(d)The National Hurricane Center (NHC)
issues forecasts on tropical weather systems (for
example, hurricanes).
(e)The Space Weather Prediction Center
(SWPC) provides alerts, watches, warnings and
forecasts for space weather events (for example, solar
storms) affecting or expected to affect Earth’s
environment.
(f)The Weather Prediction Center (WPC)
provides analysis and forecast products on a national
scale including surface pressure and frontal analyses.
6.NOAA operates two V olcanic Ash Advisory
Centers (V AAC) which issue forecasts of ash clouds
following a volcanic eruption in their area of
responsibility.
7.Details on the products provided by the above
listed offices and centers is available in FAA
Advisory Circular 00-45, A viation Weather Services.
d.Weather element values may be expressed by
using different measurement systems depending onseveral factors, such as whether the weather products
will be used by the general public, aviation interests,
international services, or a combination of these
AIM 10/12/17
7−1−2 Meteorologyusers. FIG 7−1−1 provides conversion tables for the
most used weather elements that will be encountered
by pilots.
7−1−2. FAA Weather Services
a.The FAA provides the Flight Service program,
which serves the weather needs of pilots through itsflight service stations (FSS) (both government and
contract via 1-800-WX-BRIEF) and via the Internet,
through CSC Direct User Access Terminal System(DUATS) and Lockheed Martin Flight Services
(DUATS II).
b.The FAA maintains an extensive surface
weather observing program. Airport observations(METAR and SPECI) in the U.S. are provided by
automated observing systems. Various levels of
human oversight of the METAR and SPECI reportsand augmentation may be provided at select larger
airports by either government or contract personnel
qualified to report specified weather elements thatcannot be detected by the automated observing
system.
c. Other Sources of Weather Information
1.Telephone Information Briefing Service
(TIBS) (FSS); and in Alaska, Transcribed WeatherBroadcast (TWEB) locations, and telephone access
to the TWEB (TEL −TWEB) provide continuously
updated recorded weather information for short or
local flights. Separate paragraphs in this section give
additional information regarding these services.
REFERENCE −
AIM, Paragraph 7 −1−8 , Telephone Information Briefing Service (TIBS)
AIM, Paragraph 7 −1−9 , Transcribed Weather Broadcast (TWEB)
(Alaska Only)
2.Weather and aeronautical information are
also available from numerous private industry
sources on an individual or contract pay basis.Information on how to obtain this service should be
available from local pilot organizations.
3.Pilots with a current medical certificate can
access the DUATS and Lockheed Martin FlightServices via the Internet. Pilots can receive preflight
weather data and file domestic VFR and IFR flight
plans. The following are the FAA contract vendors:
Computer Sciences Corporation (CSC)
Internet Access: http://www.duats.comFor customer service: (800) 345 −3828
Lockheed Martin Flight Services
Internet Access: http://www.1800wxbrief.com
For customer service: (866) 936 −6826
7−1−3. Use of Aviation Weather Products
a.Air carriers and operators certificated under the
provisions of 14 CFR Part 119 are required to use the
aeronautical weather information systems defined in
the Operations Specifications issued to that certifi-
cate holder by the FAA. These systems may utilize
basic F AA/National Weather Service (NWS) weather
services, contractor − or operator −proprietary weath-
er services and/or Enhanced Weather Information
System (EWINS) when approved in the Operations
Specifications. As an integral part of this system
approval, the procedures for collecting, producingand disseminating aeronautical weather information,
as well as the crew member and dispatcher training to
support the use of system weather products, must beaccepted or approved.
b.Operators not certificated under the provisions
of 14 CFR Part 1 19 are encouraged to use F AA/NWS
products through Flight Service Stations, Direct User
Access Terminal System (DUATS), Lockheed
Martin Flight Services, and/or Flight InformationServices−Broadcast (FIS −B).
c.The suite of available aviation weather product
types is expanding, with the development of newsensor systems, algorithms and forecast models. The
FAA and NWS, supported by various weather
research laboratories and corporations under contract
to the Government, develop and implement new
aviation weather product types. The FAA’s NextGen
Aviation Weather Research Program (AWRP)facilitates collaboration between the NWS, the FAA,
and various industry and research representatives.
This collaboration ensures that user needs andtechnical readiness requirements are met before
experimental products mature to operational applica-
tion.
d.The AWRP manages the transfer of aviation
weather R&D to operational use through technical
review panels and conducting safety assessments toensure that newly developed aviation weather
products meet regulatory requirements and enhance
safety.
AIM 10/12/17
7−1−3 MeteorologyFIG 7−1−1
Weather Elements Conversion Tables
AIM 10/12/17
7−1−4 Meteorologye.The AWRP review and decision −making
process applies criteria to weather products at various
stages . The stages are composed of the following:
1.Sponsorship of user needs.
2.R & D and controlled testing.
3.Experimental application.
4.Operational application.
f.Pilots and operators should be aware that
weather services provided by entities other than FAA,
NWS or their contractors (such as the DUATS and
Lockheed Martin Flight Services DUATS II) may not
meet FAA/NWS quality control standards. Hence,operators and pilots contemplating using such
services should request and/or review an appropriate
description of services and provider disclosure. Thisshould include, but is not limited to, the type of
weather product (for exampl e, current weather or
forecast weather), the currency of the product (that is,
product issue and valid times), and the relevance of
the product. Pilots and operators should be cautious
when using unfamiliar products, or products notsupported by FAA/NWS technical specifications.
NOTE−
When in doubt, consult with a F AA Flight Service Station
Specialist.
g.In addition, pilots and operators should be
aware there are weather services and productsavailable from government or ganizations beyond the
scope of the AWRP process mentioned earlier in this
section. Fo r example, governmental agencies such as
the NWS and the A viation Weather Center (AWC), or
research organizations such as the National Center
for Atmospheric Research (NCAR) display weather“model data” and “experimental” products which
require training and/or expertise to properly interpret
and use. These products are developmental proto-types that are subject to ongoing research and can
change without notice. Therefore, some data on
display by government or ganizations, or government
data on display by independent or ganizations may be
unsuitable for flight planning purposes. Operators
and pilots contemplating using such services shouldrequest and/or review an appropriate description of
services and provider disclosure. This should include,
but is not limited to, the type of weather product (forexample, current weather or forecast weather), the
currency of the product (i.e., product issue and valid
times), and the relevance of the product. Pilots andoperators should be cautious when using unfamiliar
weather products.
NOTE−
When in doubt, consult with a F AA Flight Service StationSpecialist.
h.With increased access to weather products via
the public Internet, the aviation community hasaccess to an over whelming amount of weather
information and data that support self-briefing. FAA
AC 00-45 (current edition) describes the weatherproducts distributed by the NWS. Pilots and
operators using the public Internet to access weather
from a third party vendor should request and/orreview an appropriate description of services and
provider disclosure. This should include, but is not
limited to, the type of weather product (for example,
current weather or forecast weather), the currency of
the product (i.e., product issue and valid times), and
the relevance of the product. Pilots and operators
should be cautious when using unfamiliar weather
products and when in doubt, consult with a FlightService Specialist.
i.The development of new weather products,
coupled with the termination of some legacy textual
and graphical products may create confusion between
regulatory requirements and the new products. All
flight−related, aviation weather decisions must be
based on all available pertinent weather products. As
every flight is unique and the weather conditions for
that flight vary hour by hour, day to day, multipleweather products may be necessary to meet aviation
weather regulatory requirements. Many new weather
products now have a Precautionary Use Statementthat details the proper use or application of the
specific product.
j.The FAA has identified three distinct types of
weather information available to pilots and operators.
1. Observations . Raw weather data collected
by some type of sensor suite including surface andairborne observations, radar, lightning, satellite
imagery, and profilers.
2. Analysis . Enhanced depiction and/or inter-
pretation of observed weather data.
3. Forecasts . Predictions of the development
and/or movement of weather phenomena based onmeteorological observations and various mathemat-
ical models.
k.Not all sources of aviation weather information
are able to provide all three types of weather
AIM 10/12/17
7−1−5 Meteorologyinformation. The FAA has determined that operators
and pilots may utilize the following approved sources
of aviation weather information:
1. Federal Government. The FAA and NWS
collect raw weather data, analyze the observations,
and produce forecasts. The FAA and NWS
disseminate meteorological observations, analyses,and forecasts through a variety of systems. In
addition, the Federal Government is the only
approval authority for sources of weather observa-
tions; for example, contract towers and airport
operators may be approved by the Feder
al
Government to provide weather observations.
2. Enhanced Weather Information System
(EWINS). An EWINS is an FAA authorized,
proprietary system for tracking, evaluating, report-ing, and forecasting the presence or lack of adverse
weather phenomena. The FAA authorizes a certific-
ate holder to use an EWINS to produce flightmovement forecasts, adverse weather phenomena
forecasts, and other meteorological advisories. For
more detailed information regarding EWINS, see the
Aviation Weather Services Advisory Circular 00 −45
and the Flight Standards Information Management
System 8900.1.
3. Commercial Weather Information
Providers. In general, commercial providers
produce proprietary weather products based on
NWS/FAA products with formatting and layoutmodifications but no material changes to the weather
information itself. This is also referred to as
“repackaging.” In addition, commercial providersmay produce analyses, forecasts, and other
proprietary weather products that substantially alter
the information contained in government −produced
products. However, those proprietary weather
products that substantially alter government −
produced weather products or information, may only
be approved for use by 14 CFR Part 121 and Part 135
certificate holders if the commercial provider isEWINS qualified.
NOTE−
Commercial weather information providers contracted byF AA to provide weather observations, analyses, andforecasts (e.g., contract towers) are included in the Federal
Government category of appro ved sources by virtue of
maintaining required technical and quality assurancestandards under Federal Government oversight.7−1−4. Graphical Forecasts for Aviation
(GFA)
a.The GFA website is intended to provide the
necessary aviation weather information to give users
a complete picture of the weather that may affect
flight in the continental United States (CONUS). The
website includes observational data, forecasts, and
warnings that can be viewed from 14 hours in the past
to 15 hours in the future, including thunderstorms,
clouds, flight category, precipitation, icing, turbu-
lence, and wind. Hourly model data and forecasts,
including information on clouds, flight category,
precipitation, icing, turbulence, wind, and graphical
output from the National Weather Service’s (NWS)
National Digital Forecast Data (NDFD) are available.
Wind, icing, and turbulence forecasts are available in
3,000 ft increments from the surface up to 30,000 ft
MSL, and in 6,000 ft increments from 30,000 ft MSL
to 48,000 ft MSL. Turbulence forecasts are also
broken into low (below 18,000 ft MSL) and high (at
or above 18,000 ft MSL) graphics. A maximum icing
graphic and maximum wind velocity graphic
(regardless of altitude) are also available. Built with
modern geospatial information tools, users can pan
and zoom to focus on areas of greatest interest. Target
users are commercial and general aviation pilots,
operators, briefers, and dispatchers.
b. Weather Products.
1.The Aviation Forecasts include gridded
displays of various weather parameters as well as
NWS textual weather obse rvations, forecasts, and
warnings. Icing, turbulence, and wind gridded
products are three −dimensional. Other gridded
products are two −dimensional and may represent a
“composite” of a three −dimensional weather phe-
nomenon or a surface weather variable, such as
horizontal visibility. The following are examples of
aviation forecasts depicted on the GFA:
(a)Terminal Aerodrome Forecast (TAF)
(b)Ceiling & Visibility (CIG/VIS)
(c)Clouds
(d)Precipitation / Weather (PCPN/WX)
(e)Thunderstorm (TS)
(f)Winds
(g)Turbulence
(h)Ice
AIM 10/12/17
7−1−6 Meteorology2. Observations & Warnings (Obs/Warn).
The Obs/Warn option provides an option to display
weather data for the current time and the previous
14 hours (rounded to the nearest hour). Users may
advance through time using the arrow buttons or by
clicking on the desired hour. Provided below are the
Obs/Warn product tabs available on the GFA website:
(a)METAR
(b)Precipitation/Weather (PCPN/WX)
(c)Ceiling & Visibility (CIG/VIS)
(d)Pilot Reports (PIREP)
(e)Radar & Satellite (RAD/SAT)
3.The GFA will be continuously updated and
available online at http://new.aviationweather.gov/
areafcst . Upon clicking the link above, select INFO
on the top right corner of the map display. The next
screen presents the option of selecting Overview,
Products, and Tutorial. Simply select the tab of
interest to explore the enhanced digital and graphical
weather products designed to replace the legacy FA.
Users should also refer to AC 00 −45, AviationWeather Services, for more detailed information on
the GFA.
4. GFA Static Images. Some users with
limited internet connectivity may access static
images via the Aviation Weather Center (AWC) at:
http://www.aviationweather.gov/gfa/plot . There
are two static graphical images available, titled
Aviation Cloud Forecast and Aviation Surface
Forecast . The Aviation Cloud Forecast provides
cloud coverage, bases, layers, and tops with Airmet
Sierra for mountain obscuration and Airmet Zulu for
icing overlaid. The Aviation Surface Forecast
provides visibility, weather phenomena, and winds
(including wind gusts) with Airmet Sierra for
instrument flight rules conditions and Airmet Tango
for sustained surface winds of 30 knots or more
overlaid. These images are presented on ten separate
maps providing forecast views for the entire CONUS
on one and nine regional views which provide more
detail for the user. They are updated every 3 hours and
provide forecast snapshots for 3, 6, 9, 12, 15, and
18 hours into the future. (See FIG 7−1−2 and
FIG 7−1−3.)
FIG 7−1−2
Aviation Surface Forecast
AIM 10/12/17
7−1−7 MeteorologyFIG 7−1−3
Aviation Cloud Forecast
7−1−5. Preflight Briefing
a.Flight Service Stations (FSS) are the primary
source for obtaining preflight briefings and inflightweather information. Flight Service Specialists are
qualified and certificated by the NWS as Pilot
Weather Briefers. They are not authorized to make
original forecasts, but are authorized to translate and
interpret available forecasts and reports directly intoterms describing the weather conditions which you
can expect along your flight route and at your
destination. Available aviation weather reports,forecasts and aviation weather charts are displayed at
each FSS, for pilot use. Pilots should feel free to use
these self briefing displays where available, or to ask
for a briefing or assistance from the specialist on duty.
Three basic types of preflight briefings are available
to serve your specific needs. These are: StandardBriefing, Abbreviated Briefing, and Outlook Brief-
ing. You should specify to the briefer the type of
briefing you want, along with your appropriatebackground information. This will enable the briefer
to tailor the information to your intended flight. The
following paragraphs describe the types of briefingsavailable and the information provided in each
briefing.
REFERENCE −
AIM, Paragraph 5 −1−1 , Preflight Preparation, for items that are
required.b. Standard Briefing. You should request a
Standard Briefing any time you are planning a flight
and you have not received a previous briefing or have
not received preliminary information through mass
dissemination media; for example, TIBS, TWEB(Alaska only), etc. International data may be
inaccurate or incomplete. If you are planning a flight
outside of U.S. controlled airspace, the briefer willadvise you to check data as soon as practical after
entering foreign airspace, unless you advise that you
have the international cautionary advisory. Thebriefer will automatically provide the following
information in the sequence listed, except as noted,
when it is applicable to your proposed flight.
1. Adverse Conditions. Significant meteoro-
logical and/or aeronautical information that mightinfluence the pilot to alter or cancel the proposed
flight; for example, hazardous weather conditions,
airport closures, air traffic delays, etc. Pilots shouldbe especially alert for cu rrent or forecast weather
that could reduce flight minimums below VFR or
IFR conditions. Pilots should also be alert for anyreported or forecast icing if the aircraft is not certified
for operating in icing conditions. Flying into areas
of icing or weather below minimums could havedisastrous results.
2. VFR Flight Not Recommended. When
VFR flight is proposed and sky conditions or
AIM 10/12/17
7−1−8 Meteorologyvisibilities are present or forecast, surface or aloft,
that, in the briefer’s judgment, would make flight
under VFR doubtful, the briefer will describe the
conditions, describe the affected locations, and use
the phrase “VFR flight not recommended.” This
recommendation is advisory in nature. The final
decision as to whether the flight can be conducted
safely rests solely with the pilot. Upon receiving a“VFR flight not recommended ” statement, the
non−IFR rated pilot will need to make a “go or no go”
decision. This decision should be based on weighing
the current and forecast weather conditions against
the pilot’s experience and ratings. The aircraft’s
equipment, capabilities and limitations should alsobe considered.
NOTE−
Pilots flying into areas of minimal VFR weather could
encounter unforecasted lowering conditions that place the
aircraft outside the pilot’ s ratings and experience level.This could result in spatial disorientation and/or loss ofcontrol of the aircraft.
3. Synopsis. A brief statement describing the
type, location and movement of weather systems
and/or air masses which might affect the proposed
flight.
NOTE−
These first 3 elements of a briefing may be combined in any
order when the briefer believes it will help to more clearlydescribe conditions.
4. Current Conditions. Reported weather
conditions applicable to the flight will be summarized
from all available sources; e.g., METARs/ SPECIs,PIREPs, RAREPs. This element will be omitted if the
proposed time of departure is beyond 2 hours, unless
the information is specifically requested by the pilot.
5. En Route Forecast. Forecast en route
conditions for the proposed route are summarized in
logical order; i.e., departure/climbout, en route, anddescent. (Heights are MSL, unless the contractions
“AGL” or “CIG” are denoted indicating that heights
are above ground.)
6. Destination Forecast. The destination fore-
cast for the planned ETA. Any significant changes
within 1 hour before and after the planned arrival are
included.
7. Winds Aloft. Forecast winds aloft will be
provided using degrees of the compass. The briefer
will interpolate wind directions and speeds between
levels and stations as necessary to provide expectedconditions at planned altitudes. (Heights are MSL.)
Temperature information will be provided on request.
8. Notices to Airmen (NOTAMs).
(a)Available NOTAM (D) information perti-
nent to the proposed flight, including special useairspace (SUA) NOTAMs for restricted areas, aerial
refueling, and night vision goggles (NVG).
NOTE−
Other SUA NOTAMs (D), such as military operationsarea (MOA), military training route (MTR), and warning
area NOTAMs, are considered “upon request” briefing
items as indicated in paragraph 7 −1−4b10(a).
(b)Prohibited Areas P −40, P−49, P−56,
and the special flight rules area (SFRA) for
Washington, DC.
(c)FSS briefers do not provide FDC NOTAM
information for special instrument approach proce-
dures unless specifically asked. Pilots authorized bythe FAA to use special instrument approach
procedures must specifically request FDC NOTAM
information for these procedures.
NOTE−
1.NOTAM information may be combined with current
conditions when the briefer believes it is logical to do so.
2.NOTAM (D) information and FDC NOTAMs which
have been published in the Notices to Airmen Publication
are not included in pilot briefings unless a review of thispublication is specifically requested by the pilot. For
complete flight information you are urged to review the
printed NOT AMs in the Notices to Airmen Publication and
the Chart Supplement U.S. in addition to obtaining a
briefing.
9. ATC Delays. Any known ATC delays and
flow control advisories which might affect the
proposed flight.
10. Pilots may obtain the following from
flight service station briefers upon request:
(a)Information on SUA and SUA −related
airspace, except those listed in paragraph 7 −1−4b8.
NOTE−
1.For the purpose of this paragraph, SUA and related
airspace includes the following types of airspace: alertarea, military operations area (MOA), warning area, andair traffic control assigned airspace (ATCAA). MTR dataincludes the following types of airspace: IFR training
routes (IR), VFR training routes (VR), and slow training
routes (SR).
2.Pilots are encouraged to request updated information
from ATC facilities while in flight.
AIM 10/12/17
7−1−9 Meteorology(b)A review of the Notices to Airmen
Publication for pertinent NOTAMs and Special
Notices.
(c)Approximate density altitude data.
(d)Information regarding such items as air
traffic services and rules, customs/immigration
procedures, ADIZ rules, search and rescue, etc.
(e)GPS RAIM availability for 1 hour before
to 1 hour after ETA or a time specified by the pilot.
(f)Other assistance as required.
c. Abbreviated Briefing. Request an Abbrevia-
ted Briefing when you need information tosupplement mass disseminated data, update a
previous briefing, or when you need only one or two
specific items. Provide the briefer with appropriate
background information, the time you received the
previous information, and/or the specific itemsneeded. You should indicate the source of the
information already received so that the briefer can
limit the briefing to the information that you have not
received, and/or appreciable changes in meteorologi-
cal/aeronautical conditions since your previous
briefing. To the extent possible, the briefer willprovide the information in the sequence shown for a
Standard Briefing. If you request only one or two
specific items, the briefer will advise you if adverseconditions are present or forecast. (Adverse condi-
tions contain both meteorological and/or aeronautical
information.) Details on these conditions will beprovided at your request. International data may be
inaccurate or incomplete. If you are planning a flight
outside of U.S. controlled airspace, the briefer willadvise you to check data as soon as practical after
entering foreign airspace, unless you advise that you
have the international cautionary advisory.
d. Outlook Briefing. You should request an
Outlook Briefing whenever your proposed time of
departure is six or more hours from the time of the
briefing. The briefer will provide available forecastdata applicable to the proposed flight. This type of
briefing is provided for planning purposes only. You
should obtain a Standard or Abbreviated Briefingprior to departure in order to obtain such items as
adverse conditions, current conditions, updated
forecasts, winds aloft and NOTAMs, etc.e.When filing a flight plan only
, you will be asked
if you require the latest information on adverse
conditions pertinent to the route of flight.
f. Inflight Briefing. You are encouraged to
obtain your preflight briefing by telephone or inperson before departure. In those cases where you
need to obtain a preflight briefing or an update to a
previous briefing by radio, you should contact thenearest FSS to obtain this information. After
communications have been established, advise the
specialist of the type briefing you require and provide
appropriate background information. You will be
provided information as specified in the above
paragraphs, depending on the type of briefing
requested. En Route advisories tailored to the phase
of flight that begins after climb-out and ends withdescent to land are provided upon pilot request. Pilots
are encouraged to provide a continuous exchange of
information on weather, winds, turbulence, flightvisibility, icing, etc., between pilots and inflight
specialists. Pilots should report good weather as well
as bad, and confirm expected conditions as well asunexpected. Remember that weather conditions can
change rapidly and that a “go or no go” decision, as
mentioned in paragraph 7 −1−4b2, should be assessed
at all phases of flight.
g.Following any briefing, feel free to ask for any
information that you or the briefer may have missed
or are not understood. This way, the briefer is able to
present the information in a logical sequence, andlessens the chance of important items being
overlooked.
7−1−6. Inflight Aviation Weather Advisories
a. Background
1.Inflight Aviation Weather Advisories are
forecasts to advise en route aircraft of development of
potentially hazardous weather. Inflight aviation
weather advisories in the conterminous U.S. are
issued by the Aviation Weather Center (AWC) inKansas City, MO, as well as 20 Center Weather
Service Units (CWSU) associated with ARTCCs.
AWC also issues advisories for portions of the Gulfof Mexico, Atlantic and Pacific Oceans, which are
under the control of ARTCCs with Oceanic flight
information regions (FIRs). The Weather ForecastOffice (WFO) in Honolulu issues advisories for the
Hawaiian Islands and a large portion of the Pacific
Ocean. In Alaska, the Alaska Aviation Weather Unit
AIM 10/12/17
7−1−10 Meteorology(AAWU) issues inflight aviation weather advisories
along with the Anchorage CWSU. All heights are
referenced MSL, except in the case of ceilings (CIG)
which indicate AGL.
2.There are four types of inflight aviation
weather advisories: the SIGMET, the Convective
SIGMET, the AIRMET (text or graphical product),and the Center W eather Advisory (CWA). All of these
advisories use the same location identifiers (either
VORs, airports, or well −known geographic areas) to
describe the hazardous weather areas.
3.The Severe Weather W atch Bulletins (WWs),
(with associated Alert Messages) (AWW) supple-
ments these Inflight Aviation Weather Advisories.
b. SIGMET (WS)/AIRMET (WA or
G−AIRMET)
SIGMETs/AIRMET text (WA) products are issued
corresponding to the Area Forecast (FA) areasdescribed in FIG 7 −1−4 and FIG 7 −1−5. The
maximum forecast period is 4 hours for SIGMETs
and 6 hours for AIRMETs. The G −AIRMET is issued
over the CONUS every 6 hours, valid at 3 −hour
increments through 12 hours with optional forecasts
possible during the first 6 hours. The first 6 hours ofthe G−AIRMET correspond to the 6 −hour period of
the AIRMET. SIGMETs and AIRMETs are consid-
ered “widespread” because they must be eitheraffecting or be forecasted to affect an area of at least
3,000 square miles at any one time. However, if the
total area to be affected during the forecast period isvery large, it could be that in actuality only a small
portion of t his total area would be affected at any one
time.
1.SIGMETs/AIRMET (or G−AIRMET) for the
conterminous U.S. (CONUS)
SIGMETs/AIRMET text products for the CONUS
are issued corresponding to the areas in FIG 7−1−4.
The maximum forecast period for a CONUS
SIGMET is 4 hours and 6 hours for CONUSAIRMETs. The G −AIRMET is issued over the
CONUS every 6 hours, valid at 3 −hour increments
through 12 hours with op tional forecasts possible
during the first 6 hours. The first 6 hours of the
G−AIRMET correspond to the 6 −hour period of the
AIRMET. SIGMETs and AIRMETs are considered“widespread” because they must be either affecting
or be forecasted to affect an area of at least 3,000
square miles at any one time. However, if the totalarea to be affected during the forecast period is very
large, it could be that in actuality only a small portion
of this total area would be affected at any one time.
Only SIGMETs for the CONUS are for non-convect-
ive weather. The U.S. issues a special category ofSIGMETs for convective weather called Convective
SIGMETs.
2.SIGMETs/AIRMETs for Alaska
Alaska SIGMETs are valid for up to 4 hours, except
for V olcanic Ash Cloud SIGMETs which are valid for
up to 6 hours. Alaska AIRMETs are valid for up to
8 hours.
3.SIGMETs/AIRMETs for Hawaii and U.S.
FIRs in the Gulf of Mexico, Caribbean, WesternAtlantic and Eastern and Central Pacific Oceans
These SIGMETs are valid for up to 4 hours, except
SIGMETs for Tropical Cyclones and V olcanic AshClouds, which are valid for up to 6 hours. AIRMETs
are issued for the Hawaiian Islands and are valid for
up to 6 hours. No AIRMETs are issued for U.S. FIRs
in the the Gulf of Mexico, Caribbean, Western
Atlantic and Pacific Oceans.
c. SIGMET
A SIGMET advises of weather that is potentially
hazardous to all aircraft. SIGMETs are unscheduledproducts that are valid for 4 hours. However,
SIGMETs associated with tropical cyclones and
volcanic ash clouds are valid for 6 hours.Unscheduled updates and corrections are issued as
necessary.
1.In the CONUS, SIGMETs are issued when
the following phenomena occur or are expected to
occur:
(a)Severe icing not associated with thunder-
storms.
(b)Severe or extreme turbulence or clear air
turbulence (CA T) not associated with thunderstorms.
(c)Widespread dust storms or sandstorms
lowering surface visibilities to below 3 miles.
(d)V olcanic ash.
2.In Alaska and Hawaii, SIGMETs are also
issued for:
(a)Tornadoes.
(b)Lines of thunderstorms.
(c)Embedded thunderstorms.
AIM 10/12/17
7−1−11 Meteorology(d)Hail greater than or equal to 3/4 inch in
diameter.
3.SIGMETs are identified by an alphabetic
designator from November through Yankee exclud-
ing Sierra and Tango. (Sierra, Tango, and Zulu are
reserved for AIRMET text [WA] products;
G−AIRMETS do not use the Sierra, Tango, or Zulu
designators.) The first issuance of a SIGMET will be
labeled as UWS (Urgent Weather SIGMET).
Subsequent issuances are at the forecaster’s discre-tion. Issuance for the same phenomenon will be
sequentially numbered, using the original designator
until the phenomenon ends. For example, the firstissuance in the Chicago (CHI) FA area for
phenomenon moving from the Salt Lake City (SLC)
FA area will be SIGMET Papa 3, if the previous twoissuances, Papa 1 and Papa 2, had been in the SLC FA
area. Note that no two dif ferent phenomena across the
country can have the same alphabetic designator atthe same time.
EXAMPLE −
Example of a SIGMET:
BOSR WS 050600
SIGMET ROMEO 2 VALID UNTIL 051000ME NH VTFROM CAR TO YSJ TO CON TO MPV TO CAROCNL SEV TURB BLW 080 EXP DUE TO STG NWLY
FLOW. CONDS CONTG BYD 1000Z.
d. Convective SIGMET (WST)
1.Convective SIGMETs are issued in the
conterminous U.S. for any of the following:
(a)Severe thunderstorm due to:
(1)Surface winds greater than or equal to
50 knots.
(2)Hail at the surface greater than or equal
to 3/4 inches in diameter.
(3)Tornadoes.
(b)Embedded thunderstorms.
(c)A line of thunderstorms.(d)Thunderstorms producing precipitation
greater than or equal to heavy precipitation affecting
40 percent or more of an area at least 3,000 square
miles.
2.Any convective SIGMET implies severe or
greater turbulence, severe icing, and low −level wind
shear. A convective SIGMET may be issued for any
convective situation that the forecaster feels is
hazardous to all categories of aircraft.
3.Convective SIGMET bulletins are issued for
the western (W), central (C), and eastern (E) United
States. (Convective SIGMETs are not issued for
Alaska or Hawaii.) The areas are separated at 87 and
107 degrees west longitude with sufficient overlap to
cover most cases when the phenomenon crosses the
boundaries. Bulletins are issued hourly at H+55.Special bulletins are issued at any time as required
and updated at H+55. If no criteria meeting
convective SIGMET requirements are observed orforecasted, the message “CONVECTIVE SIGMET...
NONE” will be issued for each area at H+55.
Individual convective SIGMETs for each area (W, C,
E) are numbered sequentially from number one each
day, beginning at 00Z. A convective SIGMET for a
continuing phenomenon will be reissued every hourat H+55 with a new number. The text of the bulletin
consists of either an observation and a forecast or just
a forecast. The forecast is valid for up to 2 hours.
EXAMPLE −
CONVECTIVE SIGMET 44C
VALID UNTIL 1455ZAR TX OKFROM 40NE ADM-40ESE MLC-10W TXK-50WNWLFK-40ENE SJT-40NE ADM
AREA TS MOV FROM 26025KT. TOPS ABV FL450.
OUTLOOK VALID 061455-061855FROM 60WSW OKC-MLC-40N TXK-40WSWIGB-VUZ-MGM-HRV-60S BTR-40NIAH-60SW SJT-40ENE LBB-60WSW OKC
WST ISSUANCES EXPD. REFER TO MOST RECENT
ACUS01 KWNS FROM STORM PREDICTION CENTERFOR SYNOPSIS AND METEOROLOGICAL DETAILS
AIM 10/12/17
7−1−12 MeteorologyFIG 7−1−4
SIGMET and AIRMET Locations − Conterminous United States
FIG 7−1−5
Hawaii Area Forecast Locations
AIM 10/12/17
7−1−13 Meteorologye. SIGMET Outside the CONUS
1.Three NWS offices have been designated by
ICAO as Meteorological Watch Offices (MWOs).
These offices are responsible for issuing SIGMETs
for designated areas outside the CONUS that includeAlaska, Hawaii, portions of the Atlantic and Pacific
Oceans, and the Gulf of Mexico.
2.The offices which issue international
SIGMETs are:
(a)The AWC in Kansas City, Missouri.
(b)The AAWU in Anchorage, Alaska.
(c)The WFO in Honolulu, Hawaii.
3.SIGMETs for outside the CONUS are issued
for 6 hours for volcanic ash clouds, 6 hours for
tropical cyclones (e.g. hurricanes and tropical
storms), and 4 hours for all other events. Like theCONUS SIGMETs, SIGMETs for outside the
CONUS are also identified by an alphabetic
designator from Alpha through Mike and arenumbered sequentially until that weather phenome-
non ends. The criteria for an international SIGMET
are:
(a)Thunderstorms occurring in lines, em-
bedded in clouds, or in large areas producingtornadoes or large hail.
(b)Tropical cyclones.
(c)Severe icing.
(d)Severe or extreme turbulence.
(e)Dust storms and sandstorms lowering
visibilities to less than 3 miles.
(f)V olcanic ash.
EXAMPLE −
Example of SIGMET Outside the U.S.:
WSNT06 KKCI 022014
SIGA0FKZMA KZNY TJZS SIGMET FOXTROT 3 VALID022015/030015 KKCI − MIAMI OCEANIC FIR NEW
YORK OCEANIC FIR SAN JUAN FIR FRQ TS WI AREA
BOUNDED BY 271 1N6807W 2156N6654W 2220N7040W
2602N7208W 2711N6807W. TOPS TO FL470. MOV NE15KT. WKN. BASED ON SAT AND LTG OBS.MOSHER
f. AIRMET
1.AIRMETs (WAs) are advisories of signifi-
cant weather phenomena but describe conditions atintensities lower than those which require the
issuance of SIGMETs. AIRMETs are intended for
dissemination to all pilots in the preflight and en route
phase of flight to enhance safety. AIRMET
information is available in two formats: text bulletins
(WA) and graphics (G −AIRMET). Both formats meet
the criteria of paragraph 7 −1−3i and are issued on a
scheduled basis every 6 hours beginning at0245 UTC. Unscheduled updates and corrections are
issued as necessary. AIRMETs contain details about
IFR, extensive mountain obscuration, turbulence,strong surface winds, icing, and freezing levels.
2.There are three AIRMETs: Sierra, Tango,
and Zulu. After the first issuance each day, scheduled
or unscheduled bulletins are numbered sequentially
for easier identification.
(a)AIRMET Sierra describes IFR conditions
and/or extensive mountain obscurations.
(b)AIRMET Tango describes moderate
turbulence, sustained surface winds of 30 knots or
greater, and/or nonconvective low −level wind shear.
(c)AIRMET Zulu describes moderate icing
and provides freezing level heights.
EXAMPLE −
Example of AIRMET Sierra issued for the Chicago FAarea:CHIS WA 131445
AIRMET SIERRA UPDT 2 FOR IFR AND MTN OBSCN
VALID UNTIL 132100.AIRMET IFR...KY FROM 20SSW HNN TO HMV TO 50ENE DYR T O20SSW
HNN CIG BLW 010/VIS BLW 3SM PCPN/BR/FG. CONDS
ENDG BY 18Z.
.AIRMET IFR....MN LSFROM INL TO 70W YQT TO 40ENE DLH TO 30WNW DLH TO 50SE GFK TO 20 ENE GFK TO
INL
CIG BLW 010/VIS BLW 3SM BR. CONDS ENDG 15 −
18Z. .AIRMET IFR....KS
FROM 30N SLN TO 60E ICT TO 40S ICT TO 50W
LBL TO 30SSW GLD TO 30N SLNCIG BLW 010/VIS BLW 3SM PCPN/BR/FG. CONDSENDG 15 −18Z.
AIRMET MTN OBSCN...KY TN
FROM HNN TO HMV TO GQO TO LOZ TO HNNMTN OBSC BY CLDS/PCPN/BR. CONDS CONTG
AIM 10/12/17
7−1−14 MeteorologyBYD 21Z THRU 03Z.
EXAMPLE −
Example of AIRMET Tango issued for the Salt Lake City
FA area:SLCT WA 131445AIRMET TANGO UPDT 2 FOR TURB VALID UNTIL132100.
AIRMET TURB...MT
FROM 40NW HVR TO 50SE BIL TO 60E DLN TO60SW YQL TO 40NW HVRMOD TURB BLW 150. CONDS DVLPG 18 −21Z.
CONDS CONTG BYD 21Z THRU 03Z.
AIRMET TURB....ID MT WY NV UT COFROM 100SE MLS TO 50SSW BFF TO 20SW BTYTO 40SW BAM TO 100SE MLSMOD TURB BTN FL310 AND FL410. CONDS
CONTG BYD 21Z ENDG 21 −00Z.
.AIRMET TURB...NV AZ NM CA AND CSTL WTRSFROM 100WSW ENI TO 40W BTY TO 40S LAS TO30ESE TBE TO INK TO ELP TO 50S TUS TO BZA
TO 20S MZB TO 150SW PYE TO 100WSW ENI
MOD TURB BTWN FL210 AND FL380. CONDSCONTG BYD 21Z THRU 03Z.....
EXAMPLE −
Example of AIRMET Zulu issued for the San Francisco
FA area:SFOZ WA 131445AIRMET ZULU UPDT 2 FOR ICE AND FRZLVL VALID
UNTIL 132100.
NO SGFNT ICE EXP OUTSIDE OF CNVTV ACT..FRZLVL....RANGING FROM SFC −105 ACRS AREA
MULT FRZLVL BLW 080 BOUNDED BY 40SE
YDC−60NNW GEG −60SW MLP −30WSW BKE −
20SW BAM −70W BAM −40SW YKM −40E HUH −
40SE YDC SFC ALG 20NNW HUH −30SSE HUH −60S SEA
50NW LKV −60WNWOAL −30SW OAL
040 ALG 40W HUH −30W HUH −30NNW SEA −40N
PDX−20NNW DSD
080 ALG 160NW FOT −80SW ONP −50SSW EUG
40SSE OED −50SSE CZQ −60E EHF−40WSW LAS
3. Graphical AIRMETs (G −AIRMETs) ,
found on the Aviation Weather Center webpage at
http://aviationweather.gov, are graphical forecasts of
en−route weather hazards valid at discrete times no
more than 3 hours apart for a period of up to 12 hours
into the future (for example, 00, 03, 06, 09, and 12
hours). Additional forecasts may be inserted duringthe first 6 hours (for example, 01, 02, 04, and 05). 00
hour represents the initial conditions, and the
subsequent graphics depict the area affected by the
particular hazard at that valid time. Forecasts valid at
00 through 06 hours correspond to the text AIRMETbulletin. Forecasts valid at 06 through 12 hours
correspond to the text bulletin outlook. G −AIRMET
depicts the following en route aviation weatherhazards:
(a)Instrument flight rule conditions (ceiling
< 1000’ and/or surface visibility <3 miles)
(b)Mountain obscuration
(c)Icing
(d)Freezing level
(e)Turbulence
(f)Low level wind shear (LLWS)
(g)Strong surface winds
G−AIRMETs are snap shots at discrete time intervals
as defined above. The text AIRMET is the result of
the production of the G −AIRMET but provided in a
time smear for a 6hr valid period. G −AIRMETs
provide a higher forecast resolution than text
AIRMET products. Since G −AIRMETs and text
AIRMETs are created from the same forecast
“production” process, there exists perfect consist-
ency between the two. Using the two together willprovide clarity of the area impacted by the weather
hazard and improve situational awareness and
decision making.
Interpolation of time periods between G −AIRMET
valid times: Users must keep in mind when using the
G−AIRMET that if a 00 hour forecast shows no
significant weather and a 03 hour forecast shows
hazardous weather, they must assume a change is
occurring during the period between the twoforecasts. It should be taken into consideration that
the hazardous weather starts immediately after the 00
hour forecast unless there is a defined initiation orending time for the h azardous weather. The same
would apply after the 03 hour forecast. The user
should assume the hazardous weather conditionis occurring between the snap shots unless informed
otherwise. For example, if a 00 hour forecast shows
no hazard, a 03 hour forecast shows the presence ofhazardous weather, and a 06 hour forecast shows no
hazard, the user should assume the hazard exists from
the 0001 hour to the 0559 hour time period.
AIM 10/12/17
7−1−15 MeteorologyEXAMPLE −
See FIG 7 −1−6 for an example of the G −AIRMET
graphical product.
g. Watch Notification Messages
The Storm Prediction Center (SPC) in Norman, OK,
issues Watch Notification Messages to provide an
area threat alert for forecast organized severethunderstorms that may produce tornadoes, large
hail, and/or convective damaging winds within the
CONUS. SPC issues three types of watch notification
messages: Aviation Watch Notification Messages,
Public Severe Thunderstorm Watch Notification
Messages, and Public Tornado Watch NotificationMessages.
It is important to note the dif ference between a Severe
Thunderstorm (or Tornado) Watch and a SevereThunderstorm (or Tornado) Warning. A watch means
severe weather is possible during the next few hours,
while a warning means that severe weather has beenobserved, or is expected within the hour. Only the
SPC issues Severe Thunderstorm and Tornado
Watches, while only NWS W eather Forecasts Of fices
issue Severe Thunderstorm and Tornado Warnings.
1.The Aviation Watch Notification Message.
The Aviation W atch Notification Message product is
an approximation of the area of the Public Severe
Thunderstorm Watch or Public Tornado Watch. Thearea may be defined as a rectangle or parallelogram
using VOR navigational aides as coordinates.
The Aviation Watch Notification Message was
formerly known as the Alert Severe Weather Watch
Bulletin (AWW). The NWS no longer uses that title
or acronym for this product. The NWS uses theacronym SAW for the Aviation Watch Notification
Message, but retains AWW in the product header for
processing by weather data systems.
EXAMPLE −
Example of an Aviation Watch Notification Message:
WWUS30 KWNS 271559SAW2SPC AWW 271559WW 568 TORNADO AR LA MS 271605Z - 280000Z
AXIS..65 STATUTE MILES EAST AND WEST OF LINE..
45ESE HEZ/NATCHEZ MS/ - 50N TUP/TUPELO MS/..AVIATION COORDS.. 55NM E/W /18WNW MCB - 60EMEM/HAIL SURF ACE AND ALOFT..3 INCHES. WIND
GUSTS..70 KNOTS. MAX TOPS TO 550. MEAN STORM
MOTION VECTOR 26030. LAT...LON 31369169 34998991 34998762 31368948 THIS IS AN APPROXIMATION TO THE WATCH AREA.
FOR A COMPLETE DEPICTION OF THE WATCH SEEWOUS64 KWNS FOR WOU2.
2.Public Severe Thunderstorm W atch Notifica-
tion Messages describe areas of expected severethunderstorms. (Severe thunderstorm criteria are
1-inch hail or larger and/or wind gusts of 50 knots [58
mph] or greater). A Public Severe ThunderstormWatch Notification Message contains the area
description and axis, the watch expiration time, a
description of hail size and thunderstorm wind gusts
expected, the definition of the watch, a call to action
statement, a list of other valid watches, a briefdiscussion of meteorological reasoning and technical
information for the aviation community.
3.Public Tornado Watch Notification Messages
describe areas where the threat of tornadoes exists. A
Public T ornado W atch Notification Message contains
the area description and axis, watch expiration time,the term “damaging tornadoes,” a description of the
largest hail size and strongest thunderstorm wind
gusts expected, the definition of the watch, a call toaction statement, a list of other valid watches, a brief
discussion of meteorological reasoning and technical
information for the aviation community. SPC mayenhance a Public Tornado Watch Notification
Message by using the words “THIS IS A
PARTICULARLY DANGEROUS SITUATION”when there is a likelihood of multiple strong (damage
of EF2 or EF3) or violent (damage of EF4 or EF5)
tornadoes.
4.Public severe thunderstorm and tornado
watch notification messages were formerly known as
the Severe Weather Watch Bulletins (WW). TheNWS no longer uses that title or acronym for this
product but retains WW in the product header for
processing by weather data systems.
EXAMPLE −
Example of a Public Tornado Watch Notification
Message:WWUS20 KWNS 050550SEL2SPC WW 051750
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 243NWS STORM PREDICTION CENTER NORMAN OK1250 AM CDT MON MAY 5 2011THE NWS ST ORM PREDICTION CENTER HAS ISSUED
A
*TORNADO WATCH FOR PORTIONS OFWESTERN AND CENTRAL ARKANSAS
AIM 10/12/17
7−1−16 MeteorologySOUTHERN MISSOURI
F AR EASTERN OKLAHOMA*EFFECTIVE THIS MONDAY MORNING FROM 1250AM UNTIL 600 AM CDT.
...THIS IS A P ARTICULARLY DANGEROUS SITU-
ATION...*PRIMARY THREATS INCLUDENUMEROUS INTENSE TORNADOES LIKELYNUMEROUS SIGNIFICANT DAMAGING WIND GUSTS
TO 80 MPH LIKELY
NUMEROUS VERY LARGE HAIL TO 4 INCHES INDIAMETER LIKELYTHE TORNADO WATCH AREA IS APPROXIMATELYALONG AND 100 STA TUTE MILES EAST AND WEST OF
A LINE FROM 15 MILES WEST NORTHWEST OF FORT
LEONARD WOOD MISSOURI TO 45 MILES SOUTHW-EST OF HOT SPRINGS ARKANSAS. FOR A COMPLETEDEPICTION OF THE WATCH SEE THE ASSOCIATEDWATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).
REMEMBER...A TORNADO WATCH MEANS CONDI-
TIONS ARE F AVORABLE FOR TORNADOES ANDSEVERE THUNDERSTORMS IN AND CLOSE TO THEWATCH AREA. PERSONS IN THESE AREAS SHOULDBE ON THE LOOKOUT FOR THREATENING WEATH-
ER CONDITIONS AND LISTEN FOR LATER
STATEMENTS AND POSSIBLE WARNINGS.OTHER WATCH INFORMATION...THIS TORNADOWATCH REPLACES TORNADO WATCH NUMBER 237.WATCH NUMBER 237 WILL NOT BE IN EFFECT
AFTER
1250 AM CDT. CONTINUE...WW 239...WW 240...WW241...WW 242...DISCUSSION...SRN MO SQUALL LINE EXPECTED TO
CONTINUE EWD...WHERE LONG/HOOKED HODO-
GRAPHS SUGGEST THREAT FOR EMBEDDED
SUPERCELLS/POSSIBLE TORNADOES. F ARTHERS...MORE WIDELY SCATTEREDSUPERCELLS WITH A THREAT FOR TORNADOESWILL PERSIST IN VERY STRONGLY DEEP SHEARED/
LCL ENVIRONMENT IN AR.
AVIATION...TORNADOES AND A FEW SEVERE THUN-
DERSTORMS WITH HAIL SURF ACE AND ALOFT TO 4INCHES. EXTREME TURBULENCE AND SURF ACEWIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI
WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26045.
5.Status reports are issued as needed to show
progress of storms and to delineate areas no longerunder the threat of s evere storm activity. Cancellation
bulletins are issued when it becomes evident that no
severe weather will develop or that storms havesubsided and are no longer severe.h. Center Weather Advisories (CWAs)
1.CWAs are unscheduled inflight, flow control,
air traffic, and air crew advisory. By nature of its short
lead time, the CWA is not a flight planning product.
It is generally a nowcast for conditions beginningwithin the next two hours. CWAs will be issued:
(a)As a supplement to an existing SIGMET,
Convective SIGMET or AIRMET.
(b)When an Inflight Advisory has not been
issued but observed or expected weather conditions
meet SIGMET/AIRMET criteria based on current
pilot reports and reinforced by other sourcesof information about existing meteorological
conditions.
(c)When observed or developing weather
conditions do not meet SIGMET, Convective
SIGMET, or AIRMET criteria; e.g., in terms ofintensity or area coverage, but current pilot reports or
other weather information sources indicate that
existing or anticipated meteorological phenomena
will adversely af fect the safe flow of air traf fic within
the ARTCC area of responsibility.
2.The following example is a CW A issued from
the Kansas City, Missouri, ARTCC. The “3” afterZKC in the first line denotes this CWA has been
issued for the third weather phenomena to occur for
the day. The “301” in the second line denotes thephenomena number again (3) and the issuance
number (01) for this phenomena. The CWA was
issued at 2140Z and is valid until 2340Z.
EXAMPLE −
ZKC3 CWA 032140
ZKC CWA 301 VALID UNTIL 032340ISOLD SVR TSTM over KCOU MOVG SWWD10 KTS ETC.
7−1−7. Categorical Outlooks
a.Categorical outlook terms, describing general
ceiling and visibility conditions for advanced
planning pu rposes are used only in area forecasts and
are defined as follows:
1. LIFR (Low IFR). Ceiling less than 500 feet
and/or visibility less than 1 mile.
2. IFR. Ceiling 500 to less than 1,000 feet
and/or visibility 1 to less than 3 miles.
3. MVFR (Marginal VFR). Ceiling 1,000 to
3,000 feet and/or visibility 3 to 5 miles inclusive.
AIM 10/12/17
7−1−17 Meteorology4. VFR. Ceiling greater than 3,000 feet and
visibility greater than 5 miles; includes sky clear.
b.The cause of LIFR, IFR, or MVFR is indicated
by either ceiling or visibility restrictions or both. Thecontraction “CIG” and/or weather and obstruction to
vision symbols are used. If winds or gusts of 25 knots
or greater are forecast for the outlook period, the word“WIND” is also included for all categories including
VFR.
EXAMPLE −
1.LIFR CIG −low IFR due to low ceiling.
2.IFR FG−IFR due to visibility restricted by fog.
3.MVFR CIG HZ FU −marginal VFR due to both ceiling
and visibility restricted by haze and smoke.
4.IFR CIG RA WIND −IFR due to both low ceiling and
visibility r estricted by rain; wind expected to be 25 knots or
greater.
7−1−8. Telephone Information Briefing
Service (TIBS)
a.TIBS, provided by FSS, is a system of
automated telephone recordings of meteorological
and aeronautical information available throughout
the United States. Based on the specific needs of each
area, TIBS provides route and/or area briefings in
addition to airspace procedures and special an-
nouncements concerning aviation interests that maybe available. Depending on user demand, other items
may be provided; for example, surface weather
observations, terminal forecasts, wind and temperat-
ures aloft forecasts, etc.
b.TIBS is not intended to be a substitute for
specialist −provided preflight briefings from FSS.
TIBS is recommended as a preliminary briefing andoften will be valuable in helping you to make a “go”
or “no go” decision.
c.Pilots are encouraged to utilize TIBS, which can
be accessed by dialing the FSS toll −free telephone
number, 1 −800−WX−BRIEF (992 −7433) or specific
published TIBS telephone numbers in certain areas.
Consult the “FSS T elephone Numbers” section of the
Chart Supplement U.S. or the Chart Supplement
Alaska or Pacific.
NOTE−
A touch−tone telephone is necessary to fully utilize TIBS.7−1−9. Transcribed Weather Broadcast
(TWEB) (Alaska Only)
Equipment is provided in Alaska by which
meteorological and aeronautical data are recorded on
tapes and broadcast continuously over selected L/MF
and VOR facilities. Broadcasts are made from a series
of individual tape recordings, and changes, as theyoccur, are transcribed onto the tapes. The information
provided varies depending on the type equipment
available. Generally, the broadcast contains asummary of adverse conditions, surface weather
observations, pilot weather reports, and a density
altitude statement (if applicable). At the discretion of
the broadcast facility, recordings may also include a
synopsis, winds aloft forecast, en route and terminal
forecast data, and radar reports. At selected locations,
telephone access to the TWEB has been provided
(TEL−TWEB). Telephone numbers for this service
are found in the Chart Supplement Alaska. These
broadcasts are made available primarily for preflight
and inflight planning, and as such, should not beconsidered as a substitute for specialist −provided
preflight briefings.
7−1−10. Inflight Weather Broadcasts
a. Weather Advisory Broadcasts. ARTCCs
broadcast a Severe Weather Forecast Alert (AWW),Convective SIGMET, SIGMET, or CWA alert once
on all frequencies, except emergency, when any part
of the area described is within 150 miles of theairspace under their jurisdiction. These broadcasts
contain SIGMET or CWA (ide ntification) and a brief
description of the weather activity and general areaaffected.
EXAMPLE −
1.Attention all aircra ft, SIGMET Delta Three, from Myton
to Tuba City to Milford, severe turbulence and severe clear
icing below one zero thousand feet. Expected to continue
beyond zero three zero zero zulu.
2.Attention all aircraft, convective SIGMET Two Seven
Eastern. From the vicinity of Elmira to Phillipsburg.
Scattered embedded thunderstor ms moving east at one
zero knots. A few intense level five cells, maximum tops fourfive zero.
3.Attention all aircraft, Kansas City Center weather
advisory one zero three. Numerous reports of moderate to
severe icing from eight to niner thousand feet in a three zero
mile radius of St. Louis. Light or negative icing reported
from four thousand to one two thousand feet remainder of
Kansas City Center area.
AIM 10/12/17
7−1−18 MeteorologyNOTE−
1.Terminal control facilities have the option to limit the
AWW, convective SIGMET, SIGMET, or CWA br oadcast as
follows: local control and approach control positions may
opt to broadcast SIGMET or CWA alerts only when any
part of the area described is within 50 miles of the airspace
under their jurisdiction.
2.In areas where HIWAS is available, ARTCC, Terminal
ATC, and FSS facilities no longer broadcast Inflight
Weather Advisories as described above in paragraph a. See
paragraphs b1 and b2 below.
b. Hazardous Inflight Weather Advisory Ser-
vice (HIW AS). HIWAS is an automated, continuous
broadcast of inflight weather advisories, provided by
FSS over select VOR outlets, which include the
following weather products: AWW, SIGMET,Convective SIGMET, CWA, AIRMET (text [WA] or
graphical [G −AIRMET] products), and urgent
PIREP. HIWAS is available throughout the conter-minous United States as an additional source of
hazardous weather information. HIWAS does not
replace preflight or inflight weather briefings fromFSS. Pilots should call FSS if there are any questions
about weather that is dif ferent than forecasted or if the
HIWAS broadcast appears to be in error.
1.Where HIWAS is available, ARTCC and
terminal ATC facilities will broadcast, upon receipt,a HIWAS alert once on all frequencies, except
emergency frequencies. Included in the broadcast
will be an alert announcement, frequency instruction,
number, and type of advisory updated; for example,
AWW, SIGMET, Convective SIGMET, or CWA.
EXAMPLE −
Attention all aircraft. Hazardous weather information
(SIGMET, Convective SIGMET, AIRMET (text [WA] or
graphical [G −AIRMET] product) , Urgent Pilot
Weather Report [UUA], or Center Weather Advisory
[CWA], Number or Numbers) for (geographical area)
available on HIWAS or Flight Service frequencies.
2.Upon notification of an update to HIWAS,
FSS will broadcast a HIWAS update announcementonce on all frequencies except emergency frequen-
cies. Included in the broadcast will be the type of
advisory updated; for example, AWW, SIGMET,Convective SIGMET, CWA, etc.
EXAMPLE −
Attention all aircraft. Hazardous weather information for(geographical area) available from Flight Service.
3.HIWAS availability is notated with VOR
listings in the Chart Supplement U.S., and is shown
by symbols on IFR Enroute Low Altitude Charts and
VFR Sectional Charts. The symbol depiction isidentified in the chart legend.
AIM 10/12/17
7−1−19 MeteorologyFIG 7−1−6
G−AIRMET Graphical Product
AIM 10/12/17
7−1−20 Meteorology7−1−11. Flight Information Services (FIS)
a. FIS . FIS is a method of disseminating
meteorological (MET) and aeronautical information
(AI) to displays in the cockpit in order to enhance
pilot situational awareness, provide decision supporttools, and improve safety. FIS augments traditional
pilot voice communication with Flight Service
Stations (FSSs), A TC facilities, or Airline Operations
Control Centers (AOCCs). FIS is not intended to
replace traditional pilot and controller/flight service
specialist/aircraft dispatcher preflight briefings or
inflight voice communications. FIS, however, can
provide textual and graphical information that canhelp abbreviate and improve the usefulness of such
communications. FIS enhances pilot situational
awareness and improves safety.
1.Data link Service Providers (DLSP) - DLSP
deploy and maintain airborne, ground-based, and, in
some cases, space-based infrastructure that supports
the transmission of AI/MET information over one or
more physical links. DLSP may provide a free of
charge or for-fee service that permits end users to
uplink and downlink AI/MET and other information.
The following are examples of DLSP:
(a)FAA FIS-B. A ground-based broadcast
service provided through the ADS-B Universal
Access Transceiver (UAT) network. The serviceprovides users with a 978 MHz data link capability
when operating within range and line-of-sight of a
transmitting ground station. FIS-B enables users ofproperly equipped aircraft to receive and display a
suite of broadcast weather and aeronautical informa-
tion products.
(b)Non-FAA FIS Systems. Several commer-
cial vendors provide customers with FIS data over
both the aeronautical spectrum and on other
frequencies using a variety of data link protocols.Services available from these providers vary greatly
and may include tier based subscriptions. Advance-
ments in bandwidth technology permits preflight aswell as inflight access to the same MET and AI
information available on the ground. Pilots and
operators using non-FAA FIS for MET and AIinformation should be knowledgeable regarding the
weather services being provided as some commercial
vendors may be repackaging NWS sourced weather,while other commercial vendors may alter the
weather information to produce vendor −tailored or
vendor−specific weather reports and forecasts.2.Three Data Link Modes. There are three data
link modes that may be used for transmitting AI and
MET information to aircraft. The intended use of the
AI and/or MET information will determine the most
appropriate data link service.
(a)Broadcast Mode: A one-way interaction
in which AI and/or MET updates or changes
applicable to a designated geographic area arecontinuously transmitted (or transmitted at repeated
periodic intervals) to all aircraft capable of receiving
the broadcast within the service volume defined bythe system network architecture.
(b)Contract/Demand Mode: A two-way
interaction in which AI and/or MET information istransmitted to an aircraft in response to a specific
request.
(c)Contract/Update Mode: A two-way inter-
action that is an extension of the Demand Mode.
Initial AI and/or MET report(s) are sent to an aircraft
and subsequent updates or changes to the AI and/orMET information that meet the contract criteria are
automatically or manually sent to an aircraft.
3.To ensure airman compliance with Federal
Aviation Regulations, manufacturer’s operating
manuals should remind airmen to contact ATC
controllers, FSS specialists, operator dispatchers, or
airline operations control centers for general and
mission critical aviation weather information and/orNAS status conditions (such as NOTAMs, Special
Use Airspace status, and other government flight
information). If FIS products are systemicallymodified (for example, are displayed as abbreviated
plain text and/or graphical depictions), the modifica-
tion process and limitations of the resultant productshould be clearly described in the vendor’s user
guidance.
4.Operational Use of FIS. Regardless of the
type of FIS system being used, several factors must
be considered when using FIS:
(a)
Before using FIS for inflight operations,
pilots and other flight crewmembers should become
familiar with the operation of the FIS system to be
used, the airborne equipment to be used, including its
system architecture, airborne system components,
coverage service volume an d other limitations of the
particular system, modes of operation and indications
of various system failures. Users should also be
familiar with the specific content and format of the
services available from the FIS provider(s). Sources
AIM 10/12/17
7−1−21 Meteorologyof information that may provide this specific
guidance include manufacturer’s manuals, training
programs, and reference guides.
(b)FIS should not serve as the sole source of
aviation weather and other operational information.ATC, FSSs, and, if applicable, AOCC VHF/HF voice
remain as a redundant method of communicating
aviation weather, NOTAMs, and other operationalinformation to aircraft in flight. FIS augments these
traditional ATC/FSS/AOCC services and, for some
products, offers the advantage of being displayed asgraphical information. By using FIS for orientation,
the usefulness of information received from
conventional means may be enhanced. For example,
FIS may alert the pilot to specific areas of concern
that will more accurately focus requests made to FSS
or AOCC for inflight updates or similar queries madeto ATC.
(c)The airspace and aeronautical environ-
ment is constantly changing. These changes occur
quickly and without warning. Critical operational
decisions should be based on use of the most current
and appropriate data available. When differences
exist between FIS and information obtained by voice
communication with ATC, FSS, and/or AOCC (ifapplicable), pilots are cautioned to use the most
recent data from the most authoritative source.
(d)FIS aviation weather products (for
example, graphical ground −based radar precipitation
depictions) are not appropriate for tactical (typical
timeframe of less than 3 minutes) avoidance of severe
weather such as negotiating a path through a weather
hazard area. FIS supports strategic (typical timeframe
of 20 minutes or more) weather decisionmaking such
as route selection to avoid a weather hazard area in its
entirety. The misuse of information beyond itsapplicability may place the pilot and aircraft in
jeopardy. In addition, FIS should never be used in lieu
of an individual preflight weather and flight planningbriefing.
(e)DLSP offer numerous MET and AI
products with information that can be layered on top
of each other. Pilots need to be aware that too much
information can have a negative effect on their
cognitive work load. Pilots need to manage theamount of information to a level that offers the most
pertinent information to that specific flight without
creating a cockpit distraction. Pilots may need toadjust the amount of information based on numerous
factors including, but not limited to, the phase of
flight, single pilot operation, autopilot availability,
class of airspace, and the weather conditions
encountered.
(f)FIS NOT AM products, including Tempor-
ary Flight Restriction (TFR) information, areadvisory −use information and are intended for
situational awareness purposes only. Cockpit dis-
plays of this information are not appropriate fortactical navigation − pilots should stay clear of any
geographic area displayed as a TFR NOTAM. Pilots
should contact FSSs and/or ATC while en route toobtain updated information and to verify the cockpit
display of NOTAM information.
(g)FIS supports better pilot decisionmaking
by increasing situational awareness. Better decision −
making is based on using information from a varietyof sources. In addition to FIS, pilots should take
advantage of other weather/NAS status sources,
including, briefings from Flight Service Stations,data from other air traffic control facilities, airline
operation control centers, pilot reports, as well as
their own observations.
(h)FAA’s Flight Information Service −
Broadcast (FIS−B).
(1)FIS−B is a ground −based broadcast
service provided through the FAA’s Automatic
Dependent Surveillance–Broadcast (ADS −B) Ser-
vices Universal Access Transceiver (UAT) network.The service provides users with a 978 MHz data link
capability when operating within range and line −of−
sight of a transmitting ground station. FIS −B enables
users of properly −equipped aircraft to receive and
display a suite of broadcast weather and aeronautical
information products.
(2)The following list represents the initial
suite of text and graphical products available through
FIS−B and provided free −of−charge. Detailed
information concerning FIS −B meteorological
products can be found in Advisory Circular 00 −45,
Aviation Weather Services, and AC 00-63, Use of
Cockpit Displays of Digital W eather and Aeronautic-
al Information. Information on Special Use Airspace(SUA), Temporary Flight Restriction (TFR), and
Notice to Airmen (NOTAM) products can be found
in Chapters 3, 4 and 5 of this manual.
AIM 10/12/17
7−1−22 Meteorology[a] Text: Aviation Routine Weather
Report (METAR) and Special Aviation Report
(SPECI);
[b] Text: Pilot W eather Report (PIREP);
[c] Text: Winds and T emperatures Aloft;
[d] Text: Terminal Aerodrome Forecast
(TAF) and amendments;
[e] Text: Notice to Airmen (NOTAM)
Distant and Flight Data Center;
[f] Text/Graphic: Airmen’s Meteorolo-
gical Conditions (AIRMET);
[g] Text/Graphic: Significant Meteoro-
logical Conditions (SIGMET);
[h] Text/Graphic: Convective SIG-
MET;
[i] Text/Graphic: Special Use Airspace
(SUA);
[j] Text/Graphic: Temporary Flight
Restriction (TFR) NOTAM; and
[k] Graphic: NEXRAD Composite Re-
flectivity Products (Regional and National).
(3)Users of FIS −B should familiarize
themselves with the operational characteristics and
limitations of the system, including: system architec-
ture; service environment; product lifecycles; modesof operation; and indications of system failure.
(4)FIS−B products are updated and
transmitted at specific intervals based primarily on
product issuance criteria. Update intervals are
defined as the rate at which the product data isavailable from the source for transmission. T ransmis-
sion intervals are defined as the amount of time within
which a new or updated product transmission must be
completed and/or the rate or repetition interval at
which the product is rebroadcast. Update and
transmission intervals for each product are providedin TBL 7−1−1.
(5)Where applicable, FIS −B products
include a look −ahead range expressed in nautical
miles (NM) for three service domains: Airport
Surface; Terminal Airspace; and Enroute/Gulf −of−
Mexico (GOMEX). TBL 7 −1−2 provides service
domain availability and look −ahead ranging for each
FIS−B product.(6)Prior to using this capability, users
should familiarize themselves with the operation of
FIS−B avionics by referencing the applicable User’s
Guides. Guidance concerning the interpretation of
information displayed should be obtained from theappropriate avionics manufacturer.
(7)FIS−B malfunctions not attributed to
aircraft system failures or covered by active NOTAM
should be reported by radio or telephone to the nearest
FSS facility.
b. Non−FAA FIS Systems. Several commercial
vendors also provide customers with FIS data over
both the aeronautical spectrum and on otherfrequencies using a variety of data link protocols. In
some cases, the vendors provide only the commu-
nications system that carries customer messages,such as the Aircraft Communications Addressing and
Reporting System (ACARS) used by many air carrier
and other operators.
1.Operators using non −FAA FIS data for
inflight weather and other operational informationshould ensure that the products used conform to
FAA/NWS standards. Specifically, aviation weather
and NAS status information should meet thefollowing criteria:
(a)The products should be either FAA/NWS
“accepted” aviation weather reports or products, or
based on FAA/NWS accepted aviation weather
reports or products. If products are used which do not
meet this criteria, they should be so identified. The
operator must determine the applicability of such
products to their particular flight operations.
(b)In the case of a weather product which is
the result of the application of a process which alters
the form, function or content of the base FAA/NWS
accepted weather product(s), that process, and any
limitations to the application of the resultant product,
should be described in the vendor’s user guidance
material.
2.An example would be a NEXRAD radar
composite/mosaic map, which has been modified by
changing the scaling resolution. The methodology of
assigning reflectivity values to the resultant imagecomponents should be described in the vendor’s
guidance material to ensure that the user can
accurately interpret the displayed data.
AIM 10/12/17
7−1−23 MeteorologyTBL 7−1−1
FIS−B Over UAT Product Update and Transmission Intervals
Product FIS-B Over UAT Service
Update Intervals1FIS-B Service
Transmission
Intervals2
AIRMET As Available 5 minutes
Convective SIGMET As Available 5 minutes
METARs/SPECIs 1 minute/As Available 5 minutes
NEXRAD Composite Reflectivity (CONUS) 15 minutes 15 minutes
NEXRAD Composite Reflectivity (Regional) 5 minutes 2.5 minutes
NOTAMs-D/FDC/TFR As Available 10 minutes
PIREP As Available 10 minutes
SIGMET As Available 5 minutes
SUA Status As Available 10 minutes
TAF/AMEND 8 Hours/As Available 10 minutes
Temperatures Aloft 12 Hours 10 minutes
Winds Aloft 12 Hours 10 minutes
1 The Update Interval is the rate at which the product data is available from the source.
2 The Transmission Interval is the amount of time within which a new or updated product transmission must be completed
and the rate or repetition interval at which the product is rebroadcast.
AIM 10/12/17
7−1−24 MeteorologyTBL 7−1−2
Product Parameters for Low/Medium/High Altitude Tier Radios
Product Surface Radios Low Altitude Tier Medium Altitude
TierHigh Altitude Tier
CONUS NEXRAD N/A CONUS NEXRADnot provided CONUS NEXRADimagery CONUS NEXRADimagery
Winds & TempsAloft 500 NM look −ahead
range500 NM look −ahead
range750 NM look −ahead
range1,000 NM look −
ahead range
METAR 100 NM look −ahead
range250 NM look −ahead
range375 NM look −ahead
rangeCONUS: CONUSClass B & C airport
METARs and 500
NM look−ahead
range
Outside of CONUS:
500 NM look-aheadrange
TAF 100 NM look −ahead
range250 NM look −ahead
range375 NM look −ahead
rangeCONUS: CONUSClass B & C airport
TAFs and 500 NM
look−ahead range
Outside of CONUS:
500 NM look-ahead
range
AIRMET, SIGMET,PIREP, and SUA/
SAA100 NM look −ahead
range. PIREP/SUA/
SAA is N/A.250 NM look −ahead
range375 NM look −ahead
range500 NM look −ahead
range
Regional NEXRAD 150 NM look −ahead
range150 NM look −ahead
range200 NM look −ahead
range250 NM look −ahead
range
NOTAMs D, FDC,and TFR 100 NM look −ahead
range100 NM look −ahead
range100 NM look −ahead
range100 NM look −ahead
range
7−1−12. Weather Observing Programs
a. Manual Observations. With only a few
exceptions, these reports are from airport locationsstaffed by FAA personnel who manually observe,
perform calculations, and enter these observations
into the (WMSCR) communication system. Theformat and coding of these observations are
contained in Paragraph 7 −1−30 , Key to Aviation
Routine Weather Report (METAR) and AerodromeForecasts (TAF).
b. Automated Weather Observing System
(AWOS).
1.Automated weather reporting systems are
increasingly being installed at airports. These
systems consist of various sensors, a processor, acomputer-generated voice subsystem, and a transmit-ter to broadcast local, minute-by-minute weather data
directly to the pilot.
NOTE−
When the barometric pressure exceeds 31.00 inches Hg.,
see Paragraph 7 −2−2 , Procedures, for the altimeter
setting procedures.
2.The AWOS observations will include the
prefix “AUTO” to indicate that the data are derived
from an automated system. Some AWOS locations
will be augmented by certified observers who willprovide weather and obstruction to vision informa-
tion in the remarks of the report when the reported
visibility is less than 7 miles. These sites, along with
the hours of augmentation, are to be published in the
Chart Supplement U.S. Augmentation is identified in
the observation as “OBSERVER WEATHER.” TheAWOS wind speed, direction and gusts, temperature,
AIM 10/12/17
7−1−25 Meteorologydew point, and altimeter setting are exactly the same
as for manual observations. The AWOS will also
report density altitude when it exceeds the field
elevation by more than 1,000 feet. The reported
visibility is derived from a sensor near the touchdown
of the primary instrument runway. The visibility
sensor output is converted to a visibility value using
a 10−minute harmonic average. The reported sky
condition/ceiling is derived from the ceilometer
located next to the visibility sensor. The AWOS
algorithm integrates the last 30 minutes of ceilometer
data to derive cloud layers and heights. This output
may also differ from the observer sky condition in
that the AWOS is totally dependent upon the cloudadvection over the sensor site.
3.These real-time systems are operationally
classified into nine basic levels:
(a) AWOS −A only reports altimeter setting;
NOTE−
Any other information is advisory only.
(b) AWOS −AV reports altimeter and
visibility;
NOTE−
Any other information is advisory only.
(c) AWOS −l usually reports altimeter setting,
wind data, temperature, dew point, and density
altitude;
(d) AWOS −2 provides the information pro-
vided by AWOS −l plus visibility; and
(e) AWOS −3 provides the information pro-
vided by AWOS −2 plus cloud/ceiling data.
(f) AWOS − 3P provides reports the same as
the AWOS 3 system, plus a precipitation identifica-
tion sensor.
(g) AWOS − 3PT reports the same as the
AWOS 3P System, plus thunderstorm/lightning
reporting capability.
(h) AWOS − 3T reports the same as AWOS 3
system and includes a thunderstorm/lightningreporting capability.
(i) AWOS − 4 reports the same as the AWOS
3 system, plus precipitation occurrence, type and
accumulation, freezing rain, thunderstorm, and
runway surface sensors.4.The information is transmitted over a discrete
VHF radio frequency or the voice portion of a local
NA V AID. AWOS transmissions on a discrete VHF
radio frequency are engineered to be receivable to a
maximum of 25 NM from the AWOS site and amaximum altitude of 10,000 feet AGL. At many
locations, AWOS signals may be received on the
surface of the airport, but local conditions may limitthe maximum AWOS reception distance and/or
altitude. The system transmits a 20 to 30 second
weather message updated each minute. Pilots should
monitor the designated frequency for the automated
weather broadcast. A description of the broadcast is
contained in subparagraph c. There is no two-waycommunication capability. Most AWOS sites also
have a dial-up capability so that the minute-by-min-
ute weather messages can be accessed via telephone.
5.AWOS information (system level, frequency,
phone number, etc.) concerning specific locations is
published, as the systems become operational, in the
Chart Supplement U.S., and where applicable, on
published Instrument Approach Procedures. Selected
individual systems may be incorporated intonationwide data collection and dissemination net-
works in the future.
c. AWOS Broadcasts. Computer-generated
voice is used in AWOS to automate the broadcast of
the minute-by-minute weather observations. In
addition, some systems are configured to permit theaddition of an operator-generated voice message;
e.g., weather remarks following the automated
parameters. The phraseology used generally follows
that used for other weather broadcasts. Following are
explanations and examples of the exceptions.
1. Location and T ime. The location/name and
the phrase “AUTOMATED WEA THER OBSERV A-
TION,” followed by the time are announced.
(a)If the airport’s specific location is
included in the airport’s name, the airport’s name is
announced.
EXAMPLE −
“Bremerton National Airport automated weather observa-
tion, one four five six zulu;”
“Ravenswood Jackson County Airport automated weather
observation, one four five six zulu.”
(b)If the airport’s specific location is not
included in the airport’s name, the location is
announced followed by the airport’s name.
AIM 10/12/17
7−1−26 MeteorologyEXAMPLE −
“Sault Ste. Marie, Chippewa County International Airport
automated weather observation;”“Sandusky, Cowley Field automated weather
observation.”
(c)The word “TEST” is added following
“OBSERV ATION” when the system is not in
commissioned status.
EXAMPLE −
“Bremerton National Airport automated weather observa-
tion test, one four five six zulu.”
(d)The phrase “TEMPORARILY INOP-
ERATIVE” is added when the system is inoperative.
EXAMPLE −
“Bremerton National Airport automated weather observ-ing system temporarily inoperative.”
2. Visibility.
(a)The lowest reportable visibility value in
AWOS is “less than 1/4.” It is announced as
“VISIBILITY LESS THAN ONE QUARTER.”
(b)A sensor for determining visibility is not
included in some AWOS. In these systems, visibility
is not announced. “VISIBILITY MISSING” is
announced only if the system is configured with avisibility sensor and visibility information is not
available.
3. Weather. In the future, some AWOSs are to
be configured to determine the occurrence of
precipitation. However, the type and intensity maynot always be determined. In these systems, the word
“PRECIPITATION” will be announced if precipita-
tion is occurring, but the type and intensity are notdetermined.
4. Ceiling and Sky Cover.
(a)Ceiling is announced as either “CEIL-
ING” or “INDEFINITE CEILING.” With the
exception of indefinite ceilings, all automated ceiling
heights are measured.
EXAMPLE −
“Bremerton National Airport automated weather observa-
tion, one four five six zulu. Ceiling two thousand over cast;”
“Bremerton National Airport automated weather observa-
tion, one four five six zulu. Indefinite ceiling two hundred,
sky obscured.”
(b)The word “Clear” is not used in AWOS
due to limitations in the height ranges of the sensors.No clouds detected is announced as “NO CLOUDS
BELOW XXX” or, in newer systems as “CLEAR
BELOW XXX” (where XXX is the range limit of the
sensor).
EXAMPLE −
“No clouds below one two thousand.”“Clear below one two thousand.”
(c)A sensor for determining ceiling and sky
cover is not included in some AWOS. In these
systems, ceiling and sky cover are not announced.
“SKY C ONDITION MISSING” is announced only if
the system is configured with a ceilometer and theceiling and sky cover information is not available.
5. Remarks. If remarks are included in the
observation, the word “REMARKS” is announcedfollowing the altimeter setting.
(a)Automated “Remarks.”
(1)Density Altitude.
(2)Variable Visibility.
(3)Variable Wind Direction.
(b)Manual Input Remarks. Manual input
remarks are prefaced with the phrase “OBSERVER
WEATHER.” As a general rule the manual remarksare limited to:
(1)Type and intensity of precipitation.
(2)Thunderstorms and direction; and
(3)Obstructions to vision when the visibili-
ty is 3 miles or less.
EXAMPLE −
“Remarks ... density altitude, two thousand five hundred ...
visibility variable between one and two ... wind directionvariable between two four zero and three one zero...observed weather ... thunderstorm moderate rain
showers and fog ... thunderstorm overhead.”
(c)If an automated parameter is “missing”
and no manual input for that parameter is available,
the parameter is announced as “MISSING.” For
example, a report with the dew point “missing” andno manual input available, would be announced as
follows:
EXAMPLE −
“Ceiling one thousand overcast ... visibility three ...precipitation ... temperature three zero, dew point missing
... wind calm ... altimeter three zero zero one.”
(d)“REMARKS” are announced in the
following order of priority:
AIM 10/12/17
7−1−27 Meteorology(1)Automated “REMARKS.”
[a]Density Altitude.
[b]Variable Visibility.
[c]Variable Wind Direction.
(2)Manual Input “REMARKS.”
[a]Sky Condition.
[b]Visibility.
[c]Weather and Obstructions to Vision.
[d]Temperature.
[e]Dew Point.
[f]Wind; and
[g]Altimeter Setting.
EXAMPLE −
“Remarks ... density altitude, two thousand five hundred ...
visibility variable between one and two ... wind directionvariable between two four zero and three one zero ...observer ceiling estimated two thousand broken ...observer temperature two, dew point minus five.”
d. Automated Surface Observing System
(ASOS)/Automated Weather Sensor System
(AWSS). The ASOS/AWSS is the primary surface
weather observing system of the U.S. (See Key to
Decode an ASOS/AWSS (METAR) Observation,
FIG 7−1−7 and FIG 7−1−8.) The program to install
and operate these systems throughout the U.S. is a
joint ef fort of the NWS, the FAA and the Department
of Defense. AWSS is a follow −on program that
provides identical data as ASOS. ASOS/AWSS is
designed to support aviation operations and weather
forecast activities. The ASOS/AWSS will providecontinuous minute-by-minute observations and
perform the basic observing functions necessary to
generate an aviation routine weather report (ME-TAR) and other aviation weather information. The
information may be transmitted over a discrete VHF
radio frequency or the voice portion of a localNA V AID. ASOS/AWSS transmissions on a discrete
VHF radio frequency are engineered to be receivable
to a maximum of 25 NM from the ASOS/AWSS siteand a maximum altitude of 10,000 feet AGL. At many
locations, ASOS/AWSS signals may be received on
the surface of the airport, but local conditions maylimit the maximum reception distance and/or altitude.
While the automated system and the human may
differ in their methods of data collection andinterpretation, both produce an observation quite
similar in form and content. For the “objective”
elements such as pressure, ambient temperature, dew
point temperature, wind, and precipitation accumula-
tion, both the automated system and the observer use
a fixed location and time-averaging technique. The
quantitative differences between the observer and the
automated observation of these elements arenegligible. For the “subjective” elements, however,
observers use a fixed time, spatial averaging
technique to describe the visual elements (skycondition, visibility and present weather), while the
automated systems use a fixed location, time
averaging technique. Although this is a fundamentalchange, the manual and automated techniques yield
remarkably similar results within the limits of their
respective capabilities.
1. System Description.
(a)The ASOS/AWSS at each airport location
consists of four main components:
(1)Individual weather sensors.
(2)Data collection and processing units.
(3)Peripherals and displays.
(b)The ASOS/AWSS sensors perform the
basic function of data acquisition. They continuously
sample and measure the a mbient environment, derive
raw sensor data and make them available to the
collection and processing units.
2. Every ASOS/AWSS will contain the
following basic set of sensors:
(a)Cloud height indicator (one or possibly
three).
(b)Visibility sensor (one or possibly three).
(c)Precipitation identification sensor.
(d)Freezing rain sensor (at select sites).
(e)Pressure sensors (two sensors at small
airports; three sensors at large airports).
(f)Ambient temperature/Dew point tempera-
ture sensor.
(g)Anemometer (wind direction and speed
sensor).
(h)Rainfall accumulation sensor.
(i)Automated Lightning Detection and
Reporting System (ALDARS) (excluding Alaska and
Pacific Island sites).
AIM 10/12/17
7−1−28 Meteorology3. The ASOS/AWSS data outlets include:
(a)Those necessary for on-site airport users.
(b)National communications networks.
(c)Computer-generated voice (available
through FAA radio broadcast to pilots, and dial-in
telephone line).
NOTE−
Wind direction broadcast over F AA radios is in referenceto magnetic north.
4.An ASOS/AWOS/AWSS report without
human intervention will contain only that weather
data capable of being reported automatically. Themodifier for this METAR report is “AUTO.” Whenan observer augments or backs −up an ASOS/A WOS/
AWSS site, the “AUTO” modifier disappears.
5.There are two types of automated stations,
AO1 for automated weather reporting stationswithout a precipitation discriminator, and AO2 for
automated stations with a precipitation discriminator.
As appropriate, “AO1” and “AO2” must appear in
remarks. (A precipitation discriminator can deter-
mine the difference between liquid andfrozen/freezing precipitation).
NOTE−
To decode an ASOS /AWSS report, r efer to FIG 7−1−7 and
FIG 7−1−8.
REFERENCE −
A complete explanation of METAR terminology is located in AIM,
Paragraph 7 −1−30 , Key to Aerodrome Forecast (TAF) and Aviation
Routine Weather Report (METAR).
AIM 10/12/17
7−1−29 MeteorologyFIG 7−1−7
Key to Decode an ASOS /AWSS (METAR) Observation (Front)
AIM 10/12/17
7−1−30 MeteorologyFIG 7−1−8
Key to Decode an ASOS /AWSS (METAR) Observation (Back)
AIM 10/12/17
7−1−31 Meteorologye.TBL 7−1−3 contains a comparison of weather
observing programs and the elements reported.
f. Service Standards. During 1995, a govern-
ment/industry team worked to comprehensivelyreassess the requirements for surface observations at
the nation’s airports. That work resulted in agreement
on a set of service standards, and the FAA and NWSASOS sites to which the standards would apply. The
term “Service Standards” refers to the level of detail
in weather observation. The service standards consistof four different levels of service (A, B, C, and D) as
described below. Specific observational elements
included in each service level are listed inTBL 7−1−4.
1. Service Level D defines the minimum
acceptable level of service. It is a completely
automated service in which the ASOS/AWSSobservation will constitute the entire observation,
i.e., no additional weather information is added by a
human observer. This service is referred to as a stand
alone D site.
2. Service Level C is a service in which the
human observer, usually an air traffic controller,
augments or adds information to the automatedobservation. Service Level C also includes backup of
ASOS/AWSS elements in the event of an ASOS/
AWSS malfunction or an unrepresentativeASOS/AWSS report. In backup, the human observerinserts the correct or missing value for the automated
ASOS/AWSS elements. This service is provided by
air traffic controllers under the Limited Aviation
Weather Reporting Station (LAWRS) process, FSS
and NWS observers, and, at selected sites,Non−Federal Observation Program observers.
Two categories of airports require detail beyond
Service Level C in order to enhance air traf fic control
efficiency and increase system capacity. Services at
these airports are typically provided by contract
weather observers, NWS observers, and, at somelocations, FSS observers.
3. Service Level B is a service in which weather
observations consist of all elements provided under
Service Level C, plus augmentation of additional data
beyond the capability of the ASOS/AWSS. Thiscategory of airports includes smaller hubs or special
airports in other ways that have worse than average
bad weather operations for thunderstorms and/orfreezing/frozen precipitation, and/or that are remote
airports.
4. Service Level A , the highest and most
demanding category, includes all the data reported in
Service Standard B, plus additional requirements as
specified. Service Level A covers major aviation
hubs and/or high volume traffic airports with average
or worse weather.
TBL 7−1−3
Weather Observing ProgramsElement
Reported
Wind
Visibility
Temperature
Dew Point
Altimeter
Density
Altimeter
Cloud/Ceiling
PrecipitationIdentification
Thunderstorm /
Lightning
Precipitation
Occurrence
Rainfall
Accumulation
Runway Surface
Condition
Freezing Rain
Occurrence
Remarks
Type
AWSS X X X X X X X X X X
ASOS X X X X X X X X X X
AWOS−A X
AWOS−A/V X X
AWOS−1 X X X X
AWOS−2 X X X X X
AWOS−3 X X X X X X
AWOS−3P X X X X X X X
AWOS−3T X X X X X X X
AWOS−3P/T X X X X X X X X
AWOS−4 X X X X X X X X X X X X
Manual X X X X X X X
REFERENCE − FAA Order JO 7900.5B, Surface Weather Observing, for element reporting.
AIM 10/12/17
7−1−32 MeteorologyTBL 7−1−4
SERVICE LEVEL A
Service Level A consists of all the elements of
Service Levels B, C and D plus the elements
listed to the right, if observed.10 minute longline RVR at precedented sites or
additional visibility increments of 1/8, 1/16 and 0
Sector visibility
Variable sky conditionCloud layers above 12,000 feet and cloud typesWidespread dust, sand and other obscurations
V olcanic eruptions
SERVICE LEVEL B
Service Level B consists of all the elements of
Service Levels C and D plus the elements listed to
the right, if observed.Longline RVR at precedented sites
(may be instantaneous readout)
Freezing drizzle versus freezing rain
Ice pelletsSnow depth & snow increasing rapidly remarksThunderstorm and lightning location remarks
Observed significant weather not at the station
remarks
SERVICE LEVEL C
Service Level C consists of all the elements of ServiceLevel D plus augmentation and backup by a human
observer or an air traffic control specialist on location
nearby. Backup consists of inserting the correct value ifthe system malfunctions or is unrepresentative.Augmentation consists of adding the elements listed to
the right, if observed. During hours that the observing
facility is closed, the site reverts to Service Level D.ThunderstormsTornadoes
Hail
VirgaV olcanic ashTower visibility
Operationally significant remarks as deemed
appropriate by the observer
SERVICE LEVEL D
This level of service consists of an ASOS or AWSScontinually measuring the atmosphere at a point near the
runway. The ASOS or AWSS senses and measures the
weather parameters listed to the right.WindVisibility
Precipitation/Obstruction to vision
Cloud heightSky coverTemperature
Dew point
Altimeter
7−1−13. Weather Radar Services
a.The National Weather Service operates a
network of radar sites for detecting coverage,
intensity, and movement of precipitation. Thenetwork is supplemented by FAA and DOD radar
sites in the western sections of the country. Local
warning radar sites augment the network by operating
on an as needed basis to support warning and forecast
programs.
b.Scheduled radar observations are taken hourly
and transmitted in alpha-numeric format on weathertelecommunications circuits for flight planning
purposes. Under certain conditions, special radar
reports are issued in addition to the hourlytransmittals. Data contained in the reports are also
collected by the National Center for Environmental
Prediction and used to prepare national radar
summary charts for dissemination on facsimile
circuits.
c.A clear radar display (no echoes) does not mean
that there is no significant weather within the
coverage of the radar site. Clouds and fog are not
detected by the radar. However, when echoes arepresent, turbulence can be implied by the intensity of
the precipitation, and icing is implied by the presence
of the precipitation at temperatures at or below zerodegrees Celsius. Used in conjunction with other
weather products, radar provides invaluable informa-
tion for weather avoidance and flight planning.
AIM 10/12/17
7−1−33 MeteorologyFIG 7−1−9
NEXRAD Coverage
AIM 10/12/17
7−1−34 MeteorologyFIG 7−1−10
NEXRAD Coverage
AIM 10/12/17
7−1−35 MeteorologyFIG 7−1−11
NEXRAD Coverage
AIM 10/12/17
7−1−36 Meteorologyd.All En Route Flight Advisory Service facilities
and FSSs have equipment to directly access the radar
displays from the individual weather radar sites.
Specialists at these locations are trained to interpret
the display for pilot briefing and inflight advisoryservices. The Center W eather Service Units located in
ARTCCs also have access to weather radar displaysand provide support to all air traffic facilities withintheir center’s area.
e.Additional information on weather radar
products and services can be found in AC 00 −45,
Aviation Weather Services.
REFERENCE−
Pilot/Controller Glossary Term− Precipitation Radar Weather
Descriptions.
AIM, Paragraph 7 −1−28 , Thunderstorms
Chart Supplement U.S., Charts, NWS Upper Air Observing Stations and
Weather Network for the location of specific radar sites.
7−1−14. ATC Inflight Weather Avoidance
Assistance
a. ATC Radar Weather Display.
1.ATC radars are able to display areas of
precipitation by sending out a beam of radio energy
that is reflected back to the radar antenna when it
strikes an object or moisture which may be in the form
of rain drops, hail, or snow. The larger the object is,or the more dense its reflective surface, the stronger
the return will be presented. Radar weather
processors indicate the intensity of reflective returnsin terms of decibels (dBZ). ATC systems cannot
detect the presence or absence of clouds. The ATC
systems can often determine the intensity of aprecipitation area, but the specific character of that
area (snow, rain, hail, VIRGA, etc.) cannot be
determined. For this reason, ATC refers to allweather areas displayed on ATC radar scopes as
“precipitation.”
2.All ATC facilities using radar weather
processors with the ability to determine precipitation
intensity, will describe the intensity to pilots as:
(a)“LIGHT” (< 30 dBZ)
(b)“MODERATE” (30 to 40 dBZ)
(c)“HEA VY” (> 40 to 50 dBZ)
(d)“EXTREME” (> 50 dBZ)
NOTE−
En route ATC radar’ s Weather and Radar Processor(WARP) does not display light precipitation intensity.3.ATC facilities that, due to equipment
limitations, cannot display the intensity levels of
precipitation, will describe the location of the
precipitation area by geographic position, or position
relative to the aircraft. Since the intensity level is not
available, the controller will state “INTENSITYUNKNOWN.”
4.ARTCC facilities normally use a Weather and
Radar Processor (WARP) to display a mosaic of data
obtained from multiple NEXRAD sites. There is a
time delay between actual conditions and those
displayed to the controller. For example, the
precipitation data on the AR TCC controller’s display
could be up to 6 minutes old. When the WARP is not
available, a second system, the narrowband Air Route
Surveillance Radar (ARSR) can display two distinct
levels of precipitation intensity that will be described
to pilots as “MODERATE” (30 to 40 dBZ) and“HEA VY TO EXTREME” ( > 40 dBZ ). The WARP
processor is only used in ARTCC facilities.
5.ATC radar is not able to detect turbulence.
Generally, turbulence can be expected to occur as the
rate of rainfall or intensity of precipitation increases.
Turbulence associated with greater rates of rainfall/
precipitation will normally be more severe than any
associated with lesser rates of rainfall/precipitation.Turbulence should be expected to occur near
convective activity, even in clear air. Thunderstorms
are a form of convective activity that imply severe or
greater turbulence. Operation within 20 miles of
thunderstorms should be approached with greatcaution, as the severity of turbulence can be markedly
greater than the precipitation intensity might indicate.
b. Weather Avoidance Assistance.
1.To the extent possible, controllers will issue
pertinent information on weather or chaff areas andassist pilots in avoiding such areas when requested.Pilots should respond to a weather advisory by either
acknowledging the advisory or by acknowledging the
advisory and requesting an alternative course of
action as follows:
(a)Request to deviate off course by stating a
heading or degrees, direction of deviation, and
approximate number of miles. In this case, when the
requested deviation is approved, navigation is at thepilot’s prerogative, but must maintain the altitude
assigned, and remain within the lateral restrictions
issued by ATC.
AIM 10/12/17
7−1−37 Meteorology(b)An approval for lateral deviation author-
izes the pilot to maneuver left or right within the
limits specified in the clearance.
NOTE−
1.It is often necessary for ATC to restrict the amount of
lateral deviation (“twenty degrees right,” “up to fifteen
degrees left,” “up to ten degrees left or right of course”).
2.The term “when able, proceed direct,” in an ATC
weather deviation clearance, refers to the pilot’ s ability to
remain clear of the weather when returning to
course/route.
(c)Request a new route to avoid the affected
area.
(d)Request a change of altitude.
(e)Request radar vectors around the affected
areas.
2.For obvious reasons of safety, an IFR pilot
must not deviate from the course or altitude or flightlevel without a proper AT C clearance. When weather
conditions encountered are so severe that an
immediate deviation is determined to be necessaryand time will not permit approval by ATC, the pilot’s
emergency authority may be exercised.
3.When the pilot requests clearance for a route
deviation or for an ATC radar vector, the controller
must evaluate the air traffic picture in the affected
area, and coordinate with other controllers (if ATCjurisdictional boundaries may be crossed) before
replying to the request.
4.It should be remembered that the controller’s
primary function is to provide safe separationbetween aircraft. Any additional service, such as
weather avoidance assistance, can only be provided
to the extent that it does not derogate the primaryfunction. It’s also worth noting that the separation
workload is generally greater than normal when
weather disrupts the usual flow of traffic. ATC radar
limitations and frequency congestion may also be a
factor in limiting the controller’s capability toprovide additional service.
5.It is very important, therefore, that the request
for deviation or radar vector be forwarded to ATC as
far in advance as possible. Delay in submitting it maydelay or even preclude ATC approval or require that
additional restrictions be placed on the clearance.
Insofar as possible the following information shouldbe furnished to ATC when requesting clearance to
detour around weather activity:
(a)Proposed point where detour will
commence.
(b)Proposed route and extent of detour
(direction and distance).
(c)Point where original route will be
resumed.
(d)Flight conditions (IFR or VFR).
(e)Any further deviation that may become
necessary as the flight progresses.
(f)Advise if the aircraft is equipped with
functioning airborne radar.
6.To a large degree, the assistance that might be
rendered by ATC will depend upon the weatherinformation available to controllers. Due to the
extremely transitory nature of severe weather
situations, the controller’s weather information maybe of only limited value if based on weather observed
on radar only. Frequent updates by pilots giving
specific information as to the area af fected, altitudes,
intensity and nature of the severe weather can be of
considerable value. Such reports are relayed by radio
or phone to other pilots and controllers and also
receive widespread teletypewriter dissemination.
7.Obtaining IFR clearance or an ATC radar
vector to circumnavigate severe weather can often beaccommodated more readily in the en route areas
away from terminals because there is usually less
congestion and, therefore, offer greater freedom ofaction. In terminal areas, the problem is more acute
because of traffic density, ATC coordination
requirements, complex departure and arrival routes,adjacent airports, etc. As a consequence, controllers
are less likely to be able to accommodate all requests
for weather detours in a terminal area or be in aposition to volunteer such routing to the pilot.
Nevertheless, pilots should not hesitate to advise
controllers of any observed severe weather andshould specifically advise controllers if they desire
circumnavigation of observed weather.
c. Procedures for Weather Deviations and
Other Contingencies in Oceanic ControlledAirspace.
1.When the pilot initiates communications with
ATC, rapid response may be obtained by stating
“WEATHER DEVIATION REQUIRED” to indicate
AIM 10/12/17
7−1−38 Meteorologypriority is desired on the frequency and for ATC
response.
2.The pilot still retains the option of initiating
the communications using the urgency call “PAN −
PAN” 3 times to alert all listening parties of a special
handling condition which will receive ATC priorityfor issuance of a clearance or assistance.
3.ATC will:
(a)Approve the deviation.
(b)Provide vertical separation and then
approve the deviation; or
(c)If ATC is unable to establish vertical
separation, ATC must advise the pilot that standardseparation cannot be applied; provide essential traffic
information for all affected aircraft, to the extent
practicable; and if possible, suggest a course ofaction. ATC may suggest that the pilot climb or
descend to a contingency altitude (1,000 feet above or
below that assigned if operating above FL 290;500 feet above or below that assigned if operating at
or below FL 290).
PHRASEOLOGY −
STANDARD SEP ARATION NOT AVAILABLE, DEVIATE
AT PILOT’S DISCRETION; SUGGEST CLIMB (or
descent) TO (appropriate altitude); TRAFFIC (positionand altitude); REPORT DEVIATION COMPLETE.
4.The pilot will follow the ATC advisory
altitude when approximately 10 NM from track aswell as execute the procedures detailed in para-
graph 7−1−14c5.
5.If contact cannot be established or revised
ATC clearance or advisory is not available anddeviation from track is required, the pilot must take
the following actions:
(a)If possible, deviate away from an
organized track or route system.
(b)Broadcast aircraft position and intentions
on the frequency in use, as well as on frequency
121.5 MHz at suitable intervals stating: flight
identification (operator call sign), flight level, trackcode or A TS route designator, and extent of deviation
expected.
(c)Watch for conflicting traffic both visually
and by reference to TCAS (if equipped).
(d)Turn on aircraft exterior lights.(e)Deviations of less than 10 NM should
REMAIN at ASSIGNED altitude. Otherwise, when
the aircraft is approximately 10 NM from track,
initiate an altitude change based on the following
criteria:
TBL 7−1−5
Route
Centerline/TrackDeviations
>10 NMAltitude Change
EAST
(000/C0095−179/C0095
magnetic)LEFT
RIGHTDESCEND 300 ft
CLIMB 300 ft
WEST
(180/C0095−359/C0095
magnetic)LEFT
RIGHTCLIMB 300 ft
DESCEND 300 ft
Pilot Memory Slogan: “East right up,
West right down.”
(f)When returning to track, be at assigned
flight level when the aircraft is within approximately
10 NM of centerline.
(g)If contact was not established prior to
deviating, continue to attempt to contact ATC toobtain a clearance. If contact was established,
continue to keep ATC advised of intentions and
obtain essential traffic information.
7−1−15. Runway Visual Range (RVR)
There are currently two configurations of RVR in the
NAS commonly identified as Taskers and New
Generation RVR. The Taskers are the existing
configuration which uses transmissometer technolo-gy. The New Generation RVRs were deployed in
November 1994 and use forward scatter technology.
The New Generation RVRs are currently beingdeployed in the NAS to replace the existing Taskers.
a.RVR values are measured by transmissometers
mounted on 14 −foot towers along the runway. A full
RVR system consists of:
1.Transmissometer projector and related items.
2.Transmissometer receiver (detector) and
related items.
3.Analog
4. recorder.
5.Signal data converter and related items.
6.Remote digital or remote display program-
mer.
AIM 10/12/17
7−1−39 Meteorologyb.The transmissometer projector and receiver are
mounted on towers 250 feet apart. A known intensity
of light is emitted from the projector and is measured
by the receiver. Any obscuring matter such as rain,
snow, dust, fog, haze or smoke reduces the lightintensity arriving at the receiver. The resultant
intensity measurement is then converted to an RVR
value by the signal data converter. These values aredisplayed by readout equipment in the associated air
traffic facility and updated approximately once every
minute for controller issuance to pilots.
c.The signal data converter receives information
on the high intensity runway edge light setting in use(step 3, 4, or 5); transmission values from the
transmissometer and the sensing of day or night
conditions. From the three data sources, the systemwill compute appropriate RVR values.
d.An RVR transmissometer established on a
250 foot baseline provides digital readouts to a
minimum of 600 feet, which are displayed in 200 foot
increments to 3,000 feet and in 500 foot incrementsfrom 3,000 feet to a maximum value of 6,000 feet.
e.RVR values for Category IIIa operations extend
down to 700 feet RVR; however, only 600 and
800 feet are reportable RVR increments. The
800 RVR reportable value covers a range of 701 feetto 900 feet and is therefore a valid minimum
indication of Category IIIa operations.
f.Approach categories with the corresponding
minimum RVR values. (See TBL 7 −1−6.)
TBL 7−1−6
Approach Category/Minimum RVR Table
Category Visibility (RVR)
Nonprecision 2,400 feet
Category I 1,800 feet*
Category II 1,000 feet
Category IIIa 700 feet
Category IIIb 150 feet
Category IIIc 0 feet
* 1,400 feet with special equipment and authorization
g.Ten minute maximum and minimum RVR
values for the designated RVR runway are reported in
the body of the aviation weather report when the
prevailing visibility is less than one mile and/or the
RVR is 6,000 feet or less. ATCTs report RVR whenthe prevailing visibility is 1 mile or less and/or the
RVR is 6,000 feet or less.
h.Details on the requirements for the operational
use of RVR are contained in FAA AC 97 −1, Runway
Visual Range (RVR). Pilots are responsible for
compliance with minimums prescribed for their class
of operations in the appropriate CFRs and/oroperations specifications.
i.RVR values are also measured by forward
scatter meters mounted on 14 −foot frangible
fiberglass poles. A full RVR system consists of:
1.Forward scatter meter with a transmitter,
receiver and associated items.
2.A runway light intensity monitor (RLIM).
3.An ambient light sensor (ALS).
4.A data processor unit (DPU).
5.Controller display (CD).
j.The forward scatter meter is mounted on a
14−foot frangible pole. Infrared light is emitted from
the transmitter and received by the receiver. Anyobscuring matter such as rain, snow, dust, fog, haze
or smoke increases the amount of scattered light
reaching the receiver. The resulting measurementalong with inputs from the runway light intensity
monitor and the ambient light sensor are forwarded to
the DPU which calculates the proper RVR value. The
RVR values are displayed locally and remotely on
controller displays.
k.The runway light intensity monitors both the
runway edge and centerline light step settings (steps 1
through 5). Centerline light step settings are used for
CAT IIIb operations. Edge Light step settings are
used for CAT I, II, and IIIa operations.
l.New Generation RVRs can measure and display
RVR values down to the lowest limits of
Category IIIb operations (150 feet RVR). RVR
values are displayed in 100 feet increments and arereported as follows:
1.100−feet increments for products below
800 feet.
2.200−feet increments for products between
800 feet and 3,000 feet.
3.500−feet increments for products between
3,000 feet and 6,500 feet.
4.25−meter increments for products below
150 meters.
AIM 10/12/17
7−1−40 Meteorology5.50−meter increments for products between
150 meters and 800 meters.
6.100−meter increments for products between
800 meters and 1,200 meters.
7.200−meter increments for products between
1,200 meters and 2,000 meters.
7−1−16. Reporting of Cloud Heights
a.Ceiling, by definition in the CFRs and as used
in aviation weather reports and forecasts, is the height
above ground (or water) level of the lowest layer of
clouds or obscuring phenomenon that is reported as“broken,” “overcast,” or “obscuration,” e.g., an
aerodrome forecast (TAF) which reads “BKN030”
refers to height above ground level. An area forecastwhich reads “BKN030” indicates that the height is
above mean sea level.
REFERENCE −
AIM, Paragraph 7 −1−30 , Key to Aerodr ome Forecast (T AF) and A viation
Routine Weather Report (METAR), defines “broken,” “overcast,” and
“obscuration.”
b.Pilots usually report height values above MSL,
since they determine heights by the altimeter. This is
taken in account when disseminating and otherwise
applying information received from pilots. (“Ceil-
ing” heights are always above ground level.) Inreports disseminated as PIREPs, height references
are given the same as received from pilots, that is,
above MSL.
c.In area forecasts or inflight advisories, ceilings
are denoted by the contraction “CIG” when used with
sky cover symbols as in “LWRG TO CIG OVC005,”or the contraction “AGL” after, the forecast cloud
height value. When the cloud base is given in height
above MSL, it is so indicated by the contraction“MSL” or “ASL” following the height value. The
heights of clouds tops, freezing level, icing, and
turbulence are always given in heights above ASL or
MSL.
7−1−17. Reporting Prevailing Visibility
a.Surface (horizontal) visibility is reported in
METAR reports in terms of statute miles and
increments thereof; e.g., 1/16, 1/8, 3/16, 1/4, 5/16, 3/8, 1/2,
5/8, 3/4, 7/8, 1, 1 1/8, etc. (Visibility reported by an
unaugmented automated site is reported differently
than in a manual report, i.e., ASOS/AWSS: 0, 1/16, 1/8,
1/4, 1/2, 3/4, 1, 1 1/4, 1 1/2, 1 3/4, 2, 2 1/2, 3, 4, 5 , etc., A WOS:M1/4, 1/4, 1/2, 3/4, 1, 1 1/4, 1 1/2, 1 3/4, 2, 2 1/2, 3, 4, 5, etc.)
Visibility is determined through the ability to see and
identify preselected and prominent objects at a
known distance from the usual point of observation.
Visibilities which are determined to be less than7 miles, identify the obscuring atmospheric condi-
tion; e.g., fog, haze, smoke, etc., or combinations
thereof.
b.Prevailing visibility is the greatest visibility
equaled or exceeded throughout at least one half ofthe horizon circle, not necessarily contiguous.
Segments of the horizon circle which may have a
significantly different visibility may be reported inthe remarks section of the weather report; i.e., the
southeastern quadrant of the horizon circle may be
determined to be 2 miles in mist while the remaining
quadrants are determined to be 3 miles in mist.
c.When the prevailing visibility at the usual point
of observation, or at the tower level, is less than
4 miles, certificated tower personnel will take
visibility observations in addition to those taken at the
usual point of observation. The lower of these two
values will be used as the prevailing visibility for
aircraft operations.
7−1−18. Estimating Intensity of Rain and
Ice Pellets
a. Rain
1. Light. From scattered drops that, regardless
of duration, do not completely wet an exposed surfaceup to
a condition where individual drops are easily
seen.
2. Moderate. Individual drops are not clearly
identifiable; spray is observable just above pave-
ments and other hard surfaces.
3. Heavy. Rain seemingly falls in sheets;
individual drops are not identifiable; heavy spray toheight of several inches is observed over hard
surfaces.
b. Ice Pellets
1. Light. Scattered pellets that do not com-
pletely cover an exposed surface regardless of
duration. Visibility is not affected.
2. Moderate. Slow accumulation on ground.
Visibility reduced by ice pellets to less than 7 statute
miles.
AIM 10/12/17
7−1−41 Meteorology3. Heavy. Rapid accumulation on ground.
Visibility reduced by ice pellets to less than 3 statute
miles.
7−1−19. Estimating Intensity of Snow or
Drizzle (Based on Visibility)
a. Light. Visibility more than 1/2 statute mile.
b. Moderate. Visibility from more than 1/4stat-
ute mile to 1/2 statute mile.
c. Heavy. Visibility 1/4 statute mile or less.
7−1−20. Pilot Weather Reports (PIREPs)
a.FAA air traffic facilities are required to solicit
PIREPs when the following conditions are reportedor forecast: ceilings at or below 5,000 feet; visibility
at or below 5 miles (surface or aloft); thunderstorms
and related phenomena; icing of light degree orgreater; turbulence of moderate degree or greater;
wind shear and reported or forecast volcanic ash
clouds.
b.Pilots are urged to cooperate and promptly
volunteer reports of these conditions and other
atmospheric data such as: cloud bases, tops andlayers; flight visibility; precipitation; visibility
restrictions such as haze, smoke and dust; wind at
altitude; and temperature aloft.
c.PIREPs should be given to the ground facility
with which communications are established; i.e.,
FSS, ARTCC, or terminal ATC. One of the primary
duties of the Inflight position is to serve as a
collection point for the exchange of PIREPs with enroute aircraft.
d.If pilots are not able to make PIREPs by radio,
reporting upon landing of the inflight conditions
encountered to the nearest FSS or Weather Forecast
Office will be helpful. Some of the uses made of the
reports are:
1.The ATCT uses the reports to expedite the
flow of air traffic in the vicinity of the field and for
hazardous weather avoidance procedures.
2.The FSS uses the reports to brief other pilots,
to provide inflight advisories, and weather avoidance
information to en route aircraft.
3.The ARTCC uses the reports to expedite the
flow of en route traffic, to determine most favorable
altitudes, and to issue hazardous weather information
within the center’s area.4.The NWS uses the reports to verify or amend
conditions contained in aviation forecast and
advisories. In some cases, pilot reports of hazardous
conditions are the triggering mechanism for the
issuance of advisories. They also use the reports forpilot weather briefings.
5.The NWS, other government organizations,
the military, and private industry groups use PIREPs
for research activities in the study of meteorologicalphenomena.
6.All air traffic facilities and the NWS forward
the reports received from pilots into the weatherdistribution system to assure the information is made
available to all pilots and other interested parties.
e.The FAA, NWS, and other organizations that
enter PIREPs into the weather reporting system usethe format listed in TBL 7 −1−7. Items 1 through 6 are
included in all transmitted PIREPs along with one or
more of items 7 through 13. Although the PIREPshould be as complete and concise as possible, pilots
should not be overly concerned with strict format or
phraseology. The important thing is that theinformation is relayed so other pilots may benefit
from your observation. If a portion of the report needs
clarification, the ground station will request the
information. Completed PIREPs will be transmitted
to weather circuits as in the following examples:
EXAMPLE −
1.KCMH UA /OV APE 230010/TM 1516/FL085/TP
BE20/SK BKN065/WX FV03SM HZ FU/TA 20/TB LGT
NOTE−
1.One zero miles southwest of Appleton VOR; time
1516 UTC; altitude eight thousand five hundred; aircrafttype BE200; bases of the broken cloud layer is six thousand
five hundred; flight visibility 3 miles with haze and smoke;
air temperature 20 degrees Celsius; light turbulence.
EXAMPLE −
2.KCRW UV /OV KBKW 360015 −KCRW/TM
1815/FL120//TP BE99/SK IMC/WX RA/TA M08 /WV290030/TB LGT −MDT/IC LGT RIME/RM MDT MXD
ICG DURC KROA NWBND FL080 −100 1750Z
NOTE−
2.From 15 miles north of Beckley VOR to Charles-
ton VOR; time 1815 UTC; altitude 12,000 feet; typeaircraft, BE −99; in clouds; rain; temperature minus
8 Celsius; wind 290 degrees magnetic at 30 knots; light to
moderate turbulence; light rime icing during climb
northwestbound from Roanoke, VA, between 8,000 and10,000 feet at 1750 UTC.
AIM 10/12/17
7−1−42 MeteorologyTBL 7−1−7
PIREP Element Code Chart
PIREP ELEMENT PIREP CODE CONTENTS
1. 3−letter station identifier XXX Nearest weather reporting location to the reported phenomenon
2. Report type UA or UUA Routine or Urgent PIREP
3. Location /OV In relation to a VOR
4. Time /TM Coordinated Universal Time
5. Altitude /FL Essential for turbulence and icing reports
6. Type Aircraft /TP Essential for turbulence and icing reports
7. Sky cover /SK Cloud height and coverage (sky clear, few, scattered, broken, or
overcast)
8. Weather /WX Flight visibility, precipitation, restrictions to visibility, etc.
9. Temperature /TA Degrees Celsius
10. Wind /WV Direction in degrees magnetic north and speed in knots
11. Turbulence /TB See AIM paragraph 7 −1−23
12. Icing /IC See AIM paragraph 7 −1−21
13. Remarks /RM For reporting elements not included or to clarify previously
reported items
7−1−21. PIREPs Relating to Airframe Icing
a.The effects of ice on aircraft are cumulative-
thrust is reduced, drag increases, lift lessens, and
weight increases. The results are an increase in stallspeed and a deterioration of aircraft performance. In
extreme cases, 2 to 3 inches of ice can form on the
leading edge of the airfoil in less than 5 minutes. Ittakes but
1/2 inch of ice to reduce the lifting power of
some aircraft by 50 percent and increases the
frictional drag by an equal percentage.
b.A pilot can expect icing when flying in visible
precipitation, such as rain or cloud droplets, and thetemperature is between +02 and −10 degrees Celsius.
When icing is detected, a pilot should do one of two
things, particularly if the aircraft is not equipped with
deicing equipment; get out of the area of
precipitation; or go to an altitude where the
temperature is above freezing. This “warmer”
altitude may not always be a lower altitude. Proper
preflight action includes obtaining information on the
freezing level and the above freezing levels in
precipitation areas. Report icing to ATC, and if
operating IFR, request new routing or altitude if icing
will be a hazard. Be sure to give the type of aircraft to
ATC when reporting icing. The following describes
how to report icing conditions.1. Trace. Ice becomes perceptible. Rate of
accumulation slightly greater than sublimation.
Deicing/anti-icing equipment is not utilized unless
encountered for an extended period of time (over
1 hour).
2. Light. The rate of accumulation may create
a problem if flight is prolonged in this environment
(over 1 hour). Occasional use of deicing/anti-icing
equipment removes/prevents accumulation. It doesnot present a problem if the deicing/anti-icing
equipment is used.
3. Moderate. The rate of accumulation is such
that even short encounters become potentially
hazardous and use of deicing/anti-icing equipment or
flight diversion is necessary.
4. Severe. The rate of accumulation is such that
ice protection systems fail to remove the accumula-
tion of ice, or ice accumulates in locations not
normally prone to icing, such as areas aft of protected
surfaces and any other areas identified by the
manufacturer. Immediate exit from the condition isnecessary.
NOTE−
Severe icing is aircraft dependent, as are the other
categories of icing intensity. Severe icing may occur at any
accumulation rate.
AIM 10/12/17
7−1−43 MeteorologyEXAMPLE −
Pilot report: give aircraft identification, location,time (UTC), intensity of type, altitude/FL, aircrafttype, indicated air speed (IAS), and outside air
temperature (OAT).
NOTE−
1.Rime ice. Rough, milky, opaque ice formed by the
instantaneous freezing of small supercooled water
droplets.2.Clear ice. A glossy, clear, or translucent ice formed by
the relatively slow freezing of large supercooled waterdroplets.
3.The OAT should be requested by the FSS or ATC if not
included in the PIREP .
7−1−22. Definitions of Inflight Icing Terms
See TBL 7 −1−8, Icing Types, and TBL 7 −1−9, Icing
Conditions.
TBL 7−1−8
Icing Types
Clear Ice See Glaze Ice.
Glaze Ice Ice, sometimes clear and smooth, but usually containing some air pockets, which results in a
lumpy translucent appearance. Glaze ice results from supercooled drops/droplets striking a
surface but not freezing rapidly on contact. Glaze ice is denser, harder, and sometimes more
transparent than rime ice. Factors, which favor glaze formation, are those that favor slowdissipation of the heat of fusion (i.e., slight supercooling and rapid accretion). With largeraccretions, the ice shape typically includes “horns” protruding from unprotected leading edge
surfaces. It is the ice shape, rather than the clarity or color of the ice, which is most likely to
be accurately assessed from the cockpit. The terms “clear” and “glaze” have been used foressentially the same type of ice accretion, although some reserve “clear” for thinner accretions
which lack horns and conform to the airfoil.
Intercycle Ice Ice which accumulates on a protected surface between actuation cycles of a deicing system.
Known or Observed or
Detected Ice AccretionActual ice observed visually to be on the aircraft by the flight crew or identified by on −board
sensors.
Mixed Ice Simultaneous appearance or a combination of rime and glaze ice characteristics. Since theclarity, color, and shape of the ice will be a mixture of rime and glaze characteristics, accurate
identification of mixed ice from the cockpit may be difficult.
Residual Ice Ice which remains on a protected surface immediately after the actuation of a deicing system.
Rime Ice A rough, milky, opaque ice formed by the rapid freezing of supercooled drops/droplets after
they strike the aircraft. The rapid freezing results in air being trapped, giving the ice its opaque
appearance and making it porous and brittle. Rime ice typically accretes along the stagnation
line of an airfoil and is more regular in shape and conformal to the airfoil than glaze ice. It isthe ice shape, rather than the clarity or color of the ice, which is most likely to be accuratelyassessed from the cockpit.
Runback Ice Ice which forms from the freezing or refreezing of water leaving protected surfaces andrunning back to unprotected surfaces.
Note−
Ice types are difficult for the pilot to discern and have uncertain effects on an airplane in flight. Ice type definitions will
be included in the AIM for use in the “Remarks” section of the PIREP and for use in forecasting.
AIM 10/12/17
7−1−44 MeteorologyTBL 7−1−9
Icing Conditions
Appendix C Icing Conditions Appendix C (14 CFR, Part 25 and 29) is the certification icing condition standard
for approving ice protection provisions on aircraft. The conditions are specified in
terms of altitude, temperature, liquid water content (LWC), representative droplet
size (mean effective drop diameter [MED]), and cloud horizontal extent.
Forecast Icing Conditions Environmental conditions expected by a National Weather Service or anFAA−approved weather provider to be conducive to the formation of inflight icing
on aircraft.
Freezing Drizzle (FZDZ) Drizzle is precipitation at ground level or aloft in the form of liquid water drops
which have diameters less than 0.5 mm and greater than 0.05 mm. Freezing drizzle
is drizzle that exists at air temperatures less than 0 /C0095C (supercooled), remains in
liquid form, and freezes upon contact with objects on the surface or airborne.
Freezing Precipitation Freezing precipitation is freezing rain or freezing drizzle falling through or outside
of visible cloud.
Freezing Rain (FZRA) Rain is precipitation at ground level or aloft in the form of liquid water drops which
have diameters greater than 0.5 mm. Freezing rain is rain that exists at air
temperatures less than 0 /C0095C (supercooled), remains in liquid form, and freezes upon
contact with objects on the ground or in the air.
Icing in Cloud Icing occurring within visible cloud. Cloud droplets (diameter < 0.05 mm) will bepresent; freezing drizzle and/or freezing rain may or may not be present.
Icing in Precipitation Icing occurring from an encounter with freezing precipitation, that is, supercooleddrops with diameters exceeding 0.05 mm, within or outside of visible cloud.
Known Icing Conditions Atmospheric conditions in which the formation of ice is observed or detected inflight.
Note−
Because of the variability in space and time of atmospheric conditions, the existence
of a report of observed icing does not assure the presence or intensity of icingconditions at a later time, nor can a report of no icing assure the absence of icing
conditions at a later time.
Potential Icing Conditions Atmospheric icing conditions that are typically defined by airframe manufacturers
relative to temperature and visible moisture that may result in aircraft ice accretion
on the ground or in flight. The potential icing conditions are typically defined in the
Airplane Flight Manual or in the Airplane Operation Manual.
Supercooled Drizzle Drops(SCDD) Synonymous with freezing drizzle aloft.
Supercooled Drops or /Droplets Water drops/droplets which remain unfrozen at temperatures below 0 /C0095C.
Supercooled drops are found in clouds, freezing drizzle, and freezing rain in the
atmosphere. These drops may impinge and freeze after contact on aircraft surfaces.
Supercooled Large Drops (SLD) Liquid droplets with diameters greater than 0.05 mm at temperatures less than
0/C0095C, i.e., freezing rain or freezing drizzle.
AIM 10/12/17
7−1−45 Meteorology7−1−23. PIREPs Relating to Turbulence
a.When encountering turbulence, pilots are
urgently requested to report such conditions to ATC
as soon as practicable. PIREPs relating to turbulence
should state:
1.Aircraft location.
2.Time of occurrence in UTC.
3.Turbulence intensity.
4.Whether the turbulence occurred in or near
clouds.5.Aircraft altitude or flight level.
6.Type of aircraft.
7.Duration of turbulence.
EXAMPLE −
1.Over Omaha, 1232Z, moderate turbulence in clouds at
Flight Level three one zero, Boeing 707.
2.From five zero miles south of Albuquerque to three zero
miles north of Phoenix, 1250Z, occasional moderate chop
at Flight Level three three zero, DC8.
b.Duration and classification of intensity should
be made using TBL 7 −1−10.
TBL 7−1−10
Turbulence Reporting Criteria Table
Intensity Aircraft Reaction Reaction Inside Aircraft Reporting Term −Definition
Light Turbulence that momentarily causes
slight, erratic changes in altitude and/or
attitude (pitch, roll, yaw). Report asLight Turbulence;
orTurbulence that causes slight, rapid andsomewhat rhythmic bumpiness without
appreciable changes in altitude or
attitude. Report as Light Chop.Occupants may feel a slight strain
against seat belts or shoulder straps.
Unsecured objects may be displacedslightly. Food service may be con-ducted and little or no difficulty isencountered in walking.Occasional −Less than 1/3 of the time.
Intermittent −1/3 to 2/3.
Continuous −More than 2/3.
Moderate Turbulence that is similar to Light
Turbulence but of greater intensity.
Changes in altitude and/or attitude occur
but the aircraft re mains in positive
control at all times. It usually causesvariations in indicated airspeed. Reportas Moderate Turbulence;
or
Turbulence that is similar to Light Chop
but of greater intensity. It causes rapidbumps or jolts without appreciablechanges in aircraft altitude or attitude.
Report as Moderate Chop.
1Occupants feel definite strains against
seat belts or shoulder straps. Unse-
cured objects are dislodged. Foodservice and walking are difficult.NOTE
1. Pilots should report location(s),
time (UTC), intensity, whether in ornear clouds, altitude, type of aircraftand, when applicable, duration ofturbulence.
2. Duration may be based on time
between two locations or over a single
location. All locations should bereadily identifiable.
Severe Turbulence that causes large, abrupt
changes in altitude and/or attitude. It
usually causes large variations inindicated airspeed. Aircraft may bemomentarily out of control. Report as
Severe Turbulence.
1Occupants are forced violently against
seat belts or shoulder straps. Unse-
cured objects are tossed about. FoodService and walking are impossible.EXAMPLES:
a. Over Omaha. 1232Z, ModerateTurbulence, in cloud, FlightLevel 310, B707.
Extreme Turbulence in which the aircraft is
violently tossed about and is practically
impossible to control. It may causestructural damage. Report as Extreme
Turbulence.
1b. From 50 miles south of Albuquer-
que to 30 miles north of Phoenix,
1210Z to 1250Z, occasional ModerateChop, Flight Level 330, DC8.
1 High level turbulence (normally above 15,000 feet ASL) not associated with cumuliform cloudiness, including thunderstorms,
should be reported as CAT (clear air turbulence) preceded by the appropriate intensity, or light or moderate chop.
AIM 10/12/17
7−1−46 Meteorology7−1−24. Wind Shear PIREPs
a.Because unexpected changes in wind speed and
direction can be hazardous to aircraft operations atlow altitudes on approach to and departing from
airports, pilots are urged to promptly volunteer
reports to controllers of wind shear conditions theyencounter. An advance warning of this information
will assist other pilots in avoiding or coping with a
wind shear on approach or departure.
b.When describing conditions, use of the terms
“negative” or “positive” wind shear should be
avoided. PIREPs of “negative wind shear on final,”
intended to describe loss of airspeed and lift, havebeen interpreted to mean that no wind shear was
encountered. The recommended method for wind
shear reporting is to state the loss or gain of airspeedand the altitudes at which it was encountered.
EXAMPLE −
1.Denver Tower, Cessna 1234 encountered wind shear,
loss of 20 knots at 400.
2.Tulsa Tower, American 721 encountered wind shear on
final, gained 25 knots between 600 and 400 feet followed
by loss of 40 knots between 400 feet and surface.
1.Pilots who are not able to report wind shear in
these specific terms are encouraged to make reportsin terms of the effect upon their aircraft.
EXAMPLE −
Miami Tower, Gulfstream 403 Charlie encountered anabrupt wind shear at 800 feet on final, max thrust r equired.
2.Pilots using Inertial Navigation Systems
(INSs) should report the wind and altitude both above
and below the shear level.
7−1−25. Clear Air Turbulence (CAT) PIREPs
CAT has become a very serious operational factor to
flight operations at all levels and especially to jettraffic flying in excess of 15,000 feet. The best
available information on this phenomenon must
come from pilots via the PIREP reporting procedures.
All pilots encountering CAT conditions are urgently
requested to report time, location, and intensity (light,
moderate, severe, or extreme) of the element to the
FAA facility with which they are maintaining radio
contact. If time and conditions permit, elementsshould be reported according to the standards for
other PIREPs and position reports.
REFERENCE −
AIM, Paragraph 7 −1−23 , PIREPs Relating to Turbulence
7−1−26. Microbursts
a.Relatively recent meteorological studies have
confirmed the existence of microburst phenomenon.
Microbursts are small scale intense downdrafts
which, on reaching the surface, spread outward in all
directions from the downdraft center. This causes the
presence of both vertical and horizontal wind shearsthat can be extremely hazardous to all types and
categories of aircraft, especially at low altitudes. Due
to their small size, short life span, and the fact thatthey can occur over areas without surface precipita-
tion, microbursts are not easily detectable using
conventional weather radar or wind shear alertsystems.
b.Parent clouds producing microburst activity
can be any of the low or middle layer convectivecloud types. Note, however, that microbursts
commonly occur within the heavy rain portion of
thunderstorms, and in much weaker, benignappearing convective cells that have little or no
precipitation reaching the ground.
AIM 10/12/17
7−1−47 MeteorologyFIG 7−1−12
Evolution of a Microburst
T-5 MinT-5 Min T-2 MinT-2 Min TT T + 5 MinT + 5 Min T + 10 MinT + 10 Min
HEIGHT (feet)HEIGHT (feet)10,00010,000
5,0005,000WIND SPEEDWIND SPEED
10-20 knots10-20 knots
> 20 knots> 20 knots
SCALE (miles)SCALE (miles)00 123
Vertical cross section of the evolution of a microburst wind field. T is the time of initial divergence at
the surface. The shading refers to the vector wind speeds. Figure adapted from Wilson et al., 1984,Microburst Wind Structure and Evaluation of Doppler Radar for Wind Shear Detection, DOT/FAAReport No. DOT/FAA/PM-84/29, National Technical Information Service, Springfield, VA 37 pp.
c.The life cycle of a microburst as it descends in
a convective rain shaft is seen in FIG 7−1−12. An
important consideration for pilots is the fact that the
microburst intensifies for about 5 minutes after it
strikes the ground.
d. Characteristics of microbursts include:
1. Size. The microburst downdraft is typically
less than 1 mile in diameter as it descends from thecloud base to about 1,000 −3,000 feet above the
ground. In the transition zone near the ground, the
downdraft changes to a horizontal outflow that can
extend to approximately 2
1/2 miles in diameter.
2. Intensity. The downdrafts can be as strong
as 6,000 feet per minute. Horizontal winds near the
surface can be as strong as 45 knots resulting in a90 knot shear (headwind to tailwind change for a
traversing aircraft) across the microburst. These
strong horizontal winds occur within a few hundred
feet of the ground.3. Visual Signs. Microbursts can be found
almost anywhere that there is convective activity.
They may be embedded in heavy rain associated with
a thunderstorm or in light rain in benign appearing
virga. When there is little or no precipitation at thesurface accompanying the microburst, a ring of
blowing dust may be the only visual clue of its
existence.
4. Duration. An individual microburst will
seldom last longer than 15 minutes from the time it
strikes the ground until dissipation. The horizontal
winds continue to increase during the first 5 minuteswith the maximum intensity winds lasting approxi-
mately 2 −4 minutes. Sometimes microbursts are
concentrated into a line structure, and under theseconditions, activity may continue for as long as an
hour. Once microburst activity starts, multiple
microbursts in the same general area are not
uncommon and should be expected.
AIM 10/12/17
7−1−48 MeteorologyFIG 7−1−13
Microburst Encounter During Takeoff
A microburst encounter during takeoff. The airplane first encounters a headwind and experiences increasing
performance (1), this is followed in short succession by a decreasing headwind component (2), a downdraft
(3), and finally a strong tailwind (4), where 2 through 5 all result in decreasing performance of the airplane.Position (5) represents an extreme situation just prior to impact. Figure courtesy of Walter Frost, FWG
Associates, Inc., Tullahoma, Tennessee.
e.Microburst wind shear may create a severe
hazard for aircraft within 1,000 feet of the ground,
particularly during the approach to landing and
landing and take-off phases. The impact of a
microburst on aircraft which have the unfortunateexperience of penetrating one is characterized in
FIG 7−1−13. The aircraft may encounter a headwind
(performance increasing) followed by a downdraft
and tailwind (both performance decreasing), possibly
resulting in terrain impact.
AIM 10/12/17
7−1−49 MeteorologyFIG 7−1−14
NAS Wind Shear Product Systems
(33)
(39)
(36)
(9)
f. Detection of Microbursts, Wind Shear and
Gust Fronts.
1. FAA’s Integrated Wind Shear Detection
Plan.
(a)The FAA currently employs an integrated
plan for wind shear detection that will significantly
improve both the safety and capacity of the majority
of the airports currently served by the air carriers.This plan integrates several programs, such as the
Integrated Terminal Weather System (ITWS),
Terminal Doppler Weather Radar (TDWR), Weather
System Processor (WSP), and Low Level W ind Shear
Alert Systems (LLWAS) into a single strategicconcept that significantly improves the aviation
weather information in the terminal area. (See
FIG 7−1−14.)
(b)The wind shear/microburst information
and warnings are displayed on the ribbon displayterminals (RBDT) located in the tower cabs. They are
identical (and standardized) in the LLWAS, TDWR
and WSP systems, and so designed that the controller
does not need to interpret the data, but simply read the
displayed information to the pilot. The RBDTs are
constantly monitored by the controller to ensure the
rapid and timely dissemination of any hazardous
event(s) to the pilot.
AIM 10/12/17
7−1−50 MeteorologyFIG 7−1−15
LLWAS Siting Criteria
(c)The early detection of a wind shear/
micro−burst event, and the subsequent warning(s)
issued to an aircraft on approach or departure, will
alert the pilot/crew to the potential of, and to be
prepared for, a situation that could become verydangerous! Without these warnings, the aircraft may
NOT be able to climb out of, or safely transition, the
event, resulting in a catastrophe. The air carriers,working with the FAA, have developed specialized
training programs using their simulators to train and
prepare their pilots on the demanding aircraftprocedures required to escape these very dangerous
wind shear and/or microburst encounters.2. Low Level Wind Shear Alert System
(LLWAS).
(a)The LLWAS provides wind data and
software processes to detect the presence ofhazardous wind shear and microbursts in the vicinity
of an airport. Wind sensors, mounted on poles
sometimes as high as 150 feet, are (ideally) located
2,000 − 3,500 feet, but not more than 5,000 feet, from
the centerline of the runway. (See FIG 7−1−15.)
AIM 10/12/17
7−1−51 MeteorologyFIG 7−1−16
Warning Boxes
(b)LLWAS was fielded in 1988 at 110 air-
ports across the nation. Many of these systems have
been replaced by new TDWR and WSP technology.
Eventually all LLWAS systems will be phased out;
however, 39 airports will be upgraded to theLLWAS−NE (Network Expansion) system, which
employs the very latest software and sensor
technology. The new LLWAS −NE systems will not
only provide the controller with wind shear warnings
and alerts, including wind shear/microburst detection
at the airport wind sensor location, but will alsoprovide the location of the hazards relative to the
airport runway(s). It will also have the flexibility and
capability to grow with the airport as new runways are
built. As many as 32 sensors, strategically located
around the airport and in relationship to its runway
configuration, can be accommodated by theLLWAS−NE network.
3. Terminal Doppler Weather Radar
(TDWR).
(a)TDWRs are being deployed at 45 loca-
tions across the U.S. Optimum locations for TDWRs
are 8 to 12 miles off of the airport proper, and
designed to look at the airspace around and over the
airport to detect microbursts, gust fronts, wind shiftsand precipitation intensities. TDWR products advise
the controller of wind shear and microburst events
impacting all runways and the areas
1/2 mile on either
side of the extended centerline of the runways out to
3 miles on final approach and 2 miles out ondeparture.
(FIG 7−1−16 is a theoretical view of the warning
boxes, including the runway, that the software uses in
determining the location(s) of wind shear or
microbursts). These warnings are displayed (as
depicted in the examples in subparagraph 5) on theRBDT.
(b)It is very important to understand what
TDWR does NOT DO:
(1)ItDOES NOT warn of wind shear
outside of the alert boxes (on the arrival and departure
ends of the runways);
(2)ItDOES NOT detect wind shear that is
NOT a microburst or a gust front;
(3)ItDOES NOT detect gusty or cross
wind conditions; and
(4)It DOES NOT detect turbulence.
However, research and development is continuing on
these systems. Future improvements may include
such areas as storm motion (movement), improved
AIM 10/12/17
7−1−52 Meteorologygust front detection, storm growth and decay,
microburst prediction, and turbulence detection.
(c)TDWR also provides a geographical
situation display (GSD) for supervisors and traffic
management specialists for planning purposes. The
GSD displays (in color) 6 levels of weather
(precipitation), gust fronts and predicted stormmovement(s). This data is used by the tower
supervisor(s), traffic management specialists and
controllers to plan for runway changes andarrival/departure route changes in order to both
reduce aircraft delays and increase airport capacity.
4. Weather System Processor (WSP).
(a)The WSP provides the controller, supervi-
sor, traffic management specialist, and ultimately thepilot, with the same products as the terminal doppler
weather radar (TDWR) at a fraction of the cost of a
TDWR. This is accomplished by utilizing new
technologies to access the weather channel capabili-ties of the existing ASR −9 radar located on or near the
airport, thus eliminating the requirements for aseparate radar location, land acquisition, supportfacilities and the associated communication landlines
and expenses.
(b)The WSP utilizes the same RBDT display
as the TDWR and LLW AS, and, just like TDWR, also
has a GSD for planning purposes by supervisors,traffic management specialists and controllers. The
WSP GSD emulates the TDWR display, i.e., it also
depicts 6 levels of precipitation, gust fronts andpredicted storm movement, and like the TDWR GSD,
is used to plan for runway changes and arrival/depar-ture route changes in order to reduce aircraft delaysand to increase airport capacity.
(c)This system is currently under develop-
ment and is operating in a developmental test statusat the Albuquerque, New Mexico, airport. Whenfielded, the WSP is expected to be installed at34 airports across the nation, substantially increasing
the safety of the American flying public.
5. Operational aspects of LLWAS, TDWR
and WSP.
To demonstrate how this data is used by both the
controller and the pilot, 3 ribbon display examples
and their explanations are presented:
(a) MICROBURST ALERTS
EXAMPLE−
This is what the controller sees on his/her ribbon displayin the tower cab.
27A MBA 35K − 2MF 250 20
NOTE−(See FIG 7− 1−17 to see how the TDWR/WSP determines
the microburst location).
This is what the controller will say when issuing the
alert.
PHRASEOLOGY−
RUNWAY 27 ARRIVAL, MICROBURST ALERT, 35 KT
LOSS 2 MILE FINAL, THRESHOLD WIND 250 AT 20.
In plain language, the controller is telling the pilot
that on approach to runway 27, there is a microburst
alert on the approach lane to the runway, and to
anticipate or expect a 35 knot loss of airspeed atapproximately 2 miles out on final approach (where
it will first encounter the phenomena). With that
information, the aircrew is forewarned, and should be
prepared to apply wind shear/microburst escapeprocedures should they decide to continue theapproach. Additionally, the surface winds at the
airport for landing runway 27 are reported as
250 degrees at 20 knots.
NOTE−
Threshold wind is at pilot’ s request or as deemed
appropriate by the controller.
REFERENCE−FAA Order JO 7110.65, Paragraph 3 −1−8b2(a), Air T raffic Control, Low
Level Wind Shear/Microburst Advisories
AIM 10/12/17
7−1−53 MeteorologyFIG 7−1−17
Microburst Alert
(b) WIND SHEAR ALERTS
EXAMPLE −
This is what the controller sees on his/her ribbon display
in the tower cab.
27A WSA 20K − 3MF 200 15
NOTE−
(See FIG 7−1−18 to see how the TDWR/WSP determines
the wind shear location).
This is what the controller will say when issuing the
alert.
PHRASEOLOGY −
RUNWAY 27 ARRIVAL, WIND SHEAR ALERT, 20 KT
LOSS 3 MILE FINAL, THRESHOLD WIND 200 AT 15.In plain language, the controller is advising the
aircraft arriving on runway 27 that at about 3 miles
out they can expect to encounter a wind shear
condition that will decrease their airspeed by 20 knots
and possibly encounter turbulence. Additionally, theairport surface winds for landing runway 27 are
reported as 200 degrees at 15 knots.
NOTE−
Threshold wind is at pilot’ s request or as deemed
appropriate by the controller.
REFERENCE −
F AA Order JO 7110.65, Air Traffic Control, Low Level Wind
Shear/Microburst Advisories, Paragraph 3 −1−8b2(a).
AIM 10/12/17
7−1−54 MeteorologyFIG 7−1−18
Weak Microburst Alert
AIM 10/12/17
7−1−55 MeteorologyFIG 7−1−19
Gust Front Alert
(c) MULTIPLE WIND SHEAR ALERTS
EXAMPLE −
This is what the controller sees on his/her ribbon display
in the tower cab.
27A WSA 20K+ RWY 250 20
27D WSA 20K+ RWY 250 20
NOTE−
(See FIG 7−1−19 to see how the TDWR/WSP determines
the gust front/wind shear location.)
This is what the controller will say when issuing the
alert.PHRASEOLOGY −
MULTIPLE WIND SHEAR ALERTS. RUNWAY 27ARRIVAL, WIND SHEAR ALERT, 20 KT GAIN ONRUNWAY; RUNWAY 27 DEP ARTURE, WIND SHEAR
ALERT, 20 KT GAIN ON RUNWAY, WIND 250 AT 20.
EXAMPLE −
In this example, the controller is advising arriving anddeparting aircraft that they could encounter a wind shearcondition right on the runway due to a gust front(significant change of wind direction) with the possibility
of a 20 knot gain in airspeed associated with the gust fr ont.
Additionally, the airport surface winds (for the runway inuse) are reported as 250 degrees at 20 knots.
REFERENCE −
F AA Order 7110.65, Air Traffic Control, Low Level WindShear/Microburst Advisories, Paragraph 3 −1−8b2(d).
AIM 10/12/17
7−1−56 Meteorology6. The Terminal Weather Information for
Pilots System (TWIP).
(a)With the increase in the quantity and
quality of terminal weather information available
through TDWR, the next step is to provide thisinformation directly to pilots rather than relying on
voice communications from ATC. The National
Airspace System has long been in need of a means of
delivering terminal weather information to the
cockpit more efficiently in terms of both speed andaccuracy to enhance pilot awareness of weather
hazards and reduce air traffic controller workload.
With the TWIP capability, terminal weatherinformation, both alphanumerically and graphically,
is now available directly to the cockpit at 43 airports
in the U.S. NAS. (See FIG 7−1−20.)
FIG 7−1−20
TWIP Image of Convective Weather
at MCO International
(b)TWIP products are generated using
weather data from the TDWR or the Integrated
Terminal Weather System (ITWS) testbed. TWIPproducts are generated and stored in the form of text
and character graphic messages. Software has been
developed to allow TDWR or ITWS to format thedata and send the TWIP products to a database
resident at Aeronautical Radio, Inc. (ARINC). These
products can then be accessed by pilots using theARINC Aircraft Communications Addressing and
Reporting System (ACARS) data link services.
Airline dispatchers can also access this database and
send messages to specific aircraft whenever wind
shear activity begins or ends at an airport.
(c)TWIP products include descriptions and
character graphics of microburst alerts, wind shear
alerts, significant precipitation, convective activitywithin 30 NM surrounding the terminal area, and
expected weather that will impact airport operations.
During inclement weather, i.e., whenever a predeter-
mined level of precipitation or wind shear is detected
within 15 miles of the terminal area, TWIP productsare updated once each minute for text messages and
once every five minutes for character graphic
messages. During good weather (below the predeter-
mined precipitation or wind shear parameters) each
message is updated every 10 minutes. These products
are intended to improve the situational awareness ofthe pilot/flight crew , and to aid in flight planning prior
to arriving or departing the terminal area. It is
important to understand that, in the context of TWIP,
the predetermined levels for inclement versus good
weather has nothing to do with the criteria for
VFR/MVFR/IFR/LIFR; it only deals with precipita-tion, wind shears and microbursts.
TBL 7−1−11
TWIP−Equipped Airports
Airport Identifier
Andrews AFB, MD KADW
Hartsfield −Jackson Atlanta Intl Airport KATL
Nashville Intl Airport KBNA
Logan Intl Airport KBOS
Baltimore/Washington Intl Airport KBWI
Hopkins Intl Airport KCLE
Charlotte/Douglas Intl Airport KCLT
Port Columbus Intl Airport KCMH
Cincinnati/Northern Kentucky Intl Airport KCVG
Dallas Love Field Airport KDAL
James M. Cox Intl Airport KDAY
Ronald Reagan Washington National Air-
portKDCA
Denver Intl Airport KDEN
Dallas−Fort Worth Intl Airport KDFW
Detroit Metro Wayne County Airport KDTW
Newark Liberty Intl Airport KEWR
Fort Lauderdale −Hollywood Intl Airport KFLL
William P. Hobby Airport KHOU
Washington Dulles Intl Airport KIAD
George Bush Intercontinental Airport KIAH
Wichita Mid −Continent Airport KICT
Indianapolis Intl Airport KIND
AIM 10/12/17
7−1−57 MeteorologyAirport Identifier
John F. Kennedy Intl Airport KJFK
LaGuardia Airport KLGA
Kansas City Intl Airport KMCI
Orlando Intl Airport KMCO
Midway Intl Airport KMDW
Memphis Intl Airport KMEM
Miami Intl Airport KMIA
General Mitchell Intl Airport KMKE
Minneapolis St. Paul Intl Airport KMSP
Louis Armstrong New Orleans Intl Air-
portKMSY
Will Rogers World Airport KOKC
O’Hare Intl Airport KORD
Palm Beach Intl Airport KPBI
Philadelphia Intl Airport KPHL
Pittsburgh Intl Airport KPIT
Raleigh−Durham Intl Airport KRDU
Louisville Intl Airport KSDF
Salt Lake City Intl Airport KSLC
Lambert−St. Louis Intl Airport KSTL
Tampa Intl Airport KTPA
Tulsa Intl Airport KTUL
7−1−27. PIREPs Relating to Volcanic Ash
Activity
a.V olcanic eruptions which send ash into the
upper atmosphere occur somewhere around the world
several times each year. Flying into a volcanic ash
cloud can be extremely dangerous. At least twoB747s have lost all power in all four engines after
such an encounter. Regardless of the type aircraft,
some damage is almost certain to ensue after anencounter with a volcanic ash cloud. Additionally,
studies have shown that volcanic eruptions are the
only significant source of large quantities of sulphurdioxide (SO
2) gas at jet-cruising altitudes. Therefore,
the detection and subsequent reporting of SO 2 is of
significant importance. Although SO 2 is colorless, its
presence in the atmosphere should be suspected when
a sulphur-like or rotten egg odor is present throughout
the cabin.b.While some volcanoes in the U.S. are
monitored, many in remote areas are not. These
unmonitored volcanoes may erupt without prior
warning to th e aviation community. A pilot observing
a volcanic eruption who has not had previousnotification of it may be the only witness to the
eruption. Pilots are strongly encouraged to transmit a
PIREP regarding volcanic eruptions and anyobserved volcanic ash clouds or detection of sulphur
dioxide (SO
2) gas associated with volcanic activity.
c.Pilots should submit PIREPs regarding volcanic
activity using the V olcanic Activity Reporting (V AR)
form as illustrated in Appendix 2. If a V AR form isnot immediately available, relay enough information
to identify the position and type of volcanic activity.
d.Pilots s hould verbally transmit the data required
in items 1 through 8 of the V AR as soon as possible.
The data required in items 9 through 16 of the V ARshould be relayed after landing if possible.
7−1−28. Thunderstorms
a.Turbulence, hail, rain, snow, lightning, sus-
tained updrafts and downdrafts, icing conditions −all
are present in thunderstorms. While there is some
evidence that maximum turbulence exists at themiddle level of a thunderstorm, recent studies show
little variation of turbulence intensity with altitude.
b.There is no useful correlation between the
external visual appearance of thunderstorms and the
severity or amount of turbulence or hail within them.
The visible thunderstorm cloud is only a portion of a
turbulent system whose updrafts and downdrafts
often extend far beyond the visible storm cloud.Severe turbulence can be expected up to 20 miles
from severe thunderstorms. This distance decreases
to about 10 miles in less severe storms.
c.Weather radar, airborne or ground based, will
normally reflect the areas of moderate to heavyprecipitation (radar does not detect turbulence). The
frequency and severity of turbulence generally
increases with the radar reflectivity which is closelyassociated with the areas of highest liquid water
content of the storm. NO FLIGHT PATH THROUGH
AN AREA OF STRONG OR VERY STRONGRADAR ECHOES SEP ARA TED BY 20 −30 MILES
OR LESS MAY BE CONSIDERED FREE OF
SEVERE TURBULENCE.
d.Turbulence beneath a thunderstorm should not
be minimized. This is especially true when the
AIM 10/12/17
7−1−58 Meteorologyrelative humidity is low in any layer between the
surface and 15,000 feet. Then the lower altitudes may
be characterized by strong out flowing winds and
severe turbulence.
e.The probability of lightning strikes occurring to
aircraft is greatest when operating at altitudes where
temperatures are between minus 5 degrees Celsiusand plus 5 degrees Celsius. Lightning can strike
aircraft flying in the clear in the vicinity of a
thunderstorm.
f.METAR reports do not include a descriptor for
severe thunderstorms. However, by understanding
severe thunderstorm criteria, i.e., 50 knot winds or
3/4inch hail, the information is available in the report
to know that one is occurring.
g.Current weather radar systems are able to
objectively determine precipitation intensity. These
precipitation intensity areas are described as “light,”“moderate,” “heavy,” and “extreme.”
REFERENCE −
Pilot/Controller Glossary− Precipitation Radar Weather Descriptions
EXAMPLE −
1.Alert provided by an ATC facility to an aircraft:
(aircraft identification) EXTREME precipitation between
ten o’clock and two o’clock, one five miles. Precipitation
area is two five miles in diameter.
2.Alert provided by an FSS:
(aircraft identification) EXTREME precipitation two zero
miles west of Atlanta V −O−R, two five miles wide, moving
east at two zero knots, tops flight level three niner zero.
7−1−29. Thunderstorm Flying
a.Thunderstorm Avoidance. Never regard any
thunderstorm lightly, even when radar echoes are oflight intensity. Avoiding thunderstorms is the best
policy. Following are some Do’s and Don’ts of
thunderstorm avoidance:
1.Don’t land or takeoff in the face of an
approaching thunderstorm. A sudden gust front of
low level turbulence could cause loss of control.
2.Don’t attempt to fly under a thunderstorm
even if you can see through to the other side.Turbulence and wind shear under the storm could be
hazardous.
3.Don’t attempt to fly under the anvil of a
thunderstorm. There is a potential for severe and
extreme clear air turbulence.4.Don’t fly without airborne radar into a cloud
mass containing scattered embedded thunderstorms.
Scattered thunderstorms not embedded usually can
be visually circumnavigated.
5.Don’t trust the visual appearance to be a
reliable indicator of the turbulence inside athunderstorm.
6.Don’t assume that ATC will offer radar
navigation guidance or deviations around thunder-
storms.
7.Don’t use data-linked weather next genera-
tion weather radar (NEXRAD) mosaic imagery as the
sole means for negotiating a path through athunderstorm area (tactical maneuvering).
8.Do remember that the data-linked NEXRAD
mosaic imagery shows where the weather was, not
where the weather is. The weather conditions may be
15 to 20 minutes older than the age indicated on the
display.
9.Do listen to chatt er on the ATC frequency for
Pilot Weather Reports (PIREP) and other aircraft
requesting to deviate or divert.
10.Do ask ATC for radar navigation guidance
or to approve deviations around thunderstorms, if
needed.
11.Do use data-linked weather NEXRAD
mosaic imagery (for example, Flight InformationService-Broadcast (FIS-B)) for route selection to
avoid thunderstorms entirely (strategic maneuver-
ing).
12.Do advise ATC, when switched to another
controller, that you are deviating for thunderstorms
before accepting to rejoin the original route.
13.Do ensure that after an authorized weather
deviation, before accepting to rejoin the original
route, that the route of flight is clear of thunderstorms.
14. Do avoid by at least 20 miles any
thunderstorm identified as severe or giving an intense
radar echo. This is especially true under the anvil of
a large cumulonimbus.
15.Do circumnavigate the entire area if the area
has 6/10 thunderstorm coverage.
16. Do remember that vivid and frequent
lightning indicates the probability of a severe
thunderstorm.
AIM 10/12/17
7−1−59 Meteorology17.Do regard as extremely hazardous any
thunderstorm with tops 35,000 feet or higher whether
the top is visually sighted or determined by radar.
18.Do give a PIREP for the flight conditions.
19.Do divert and wait out the thunderstorms on
the ground if unable to navigate around an area of
thunderstorms.
20.Do contact Flight Service for assistance in
avoiding thunderstorms. Flight Service specialists
have NEXRAD mosaic radar imagery and NEXRAD
single site radar with unique features such as base and
composite reflectivity, echo tops, and V AD wind
profiles.
b.If you cannot avoid penetrating a thunderstorm,
following are some Do’s before entering the storm:
1.Tighten your safety belt, put on your shoulder
harness (if installed), if and secure all loose objects.
2.Plan and hold the course to take the aircraft
through the storm in a minimum time.
3.To avoid the most critical icing, establish a
penetration altitude below the freezing level or above
the level of -15ºC.
4.Verify that pitot heat is on and turn on
carburetor heat or jet engine anti-ice. Icing can berapid at any altitude and cause almost instantaneous
power failure and/or loss of airspeed indication.5.Establish power settings for turbulence
penetration airspeed recommended in the aircraft
manual.
6.Turn up cockpit lights to highest intensity to
lessen temporary blindness from lightning.
7.If using automatic pilot, disengage Altitude
Hold Mode and Speed Hold Mode. The automatic
altitude and speed controls will increase maneuversof the aircraft thus increasing structural stress.
8.If using airborne radar, tilt the antenna up and
down occasionally. This will permit the detection of
other thunderstorm activity at altitudes other than the
one being flown.
c.Following are some Do’s and Don’ts during the
thunderstorm penetration:
1.Do keep your eyes on your instruments.
Looking outside the cockpit can increase danger oftemporary blindness from lightning.
2.Don’t change power settings; maintain
settings for the recommended turbulence penetration
airspeed.
3.Do maintain constant attitude. Allow the
altitude and airspeed to fluctuate.
4.Don’t turn back once you are in the
thunderstorm. A straight course through the storm
most likely will get the aircraft out of the hazardsmost quickly. In addition, turning maneuvers increase
stress on the aircraft.
AIM 10/12/17
7−1−60 Meteorology7−1−30. Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR)
FIG 7−1−21
Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR) (Front)
Key to Aerodrome Forecast (TAF) and Aviation
Routine Weather Report (METAR) (Front)
TAF KPIT 091730Z 0918/1024 15005KT 5SM HZ FEW020 WS010/31022KT
FM091930 30015G25KT 3SM SHRA OVC015
TEMPO 0920/0922 1/2SM +TSRA OVC008CB
FM100100 27008KT 5SM SHRA BKN020 OVC040PROB30 1004/1007 1SM -RA BRFM101015 18005KT 6SM -SHRA OVC020BECMG 1013/1015 P6SM NSW SKC
NOTE : Users are cautioned to confirm DATE and TIME of the TAF. For example FM 100000 is
0000Z on the 10th . Do not confuse with 1000Z!
METAR KPIT 091955Z COR 22015G25KT 3/4SM R28L/2600FT TSRA OVC010CB 18/16 A2992 RMK
SLP045 T01820159
Forecast Explanation Report
TAF Message type: TAF -routine or TAF AMD -amended forecast, METAR -
hourly, SPECI -special or TESTM -non-commissioned ASOS reportMETAR
KPIT ICAO location indicator KPIT
091730Z Issuance time: ALL times in UTC “Z ”, 2-digit date, 4-digit time 091955Z
0918/1024 Valid period, either 24 hours or 30 hours. The first two digits of EACHfour digit number indicate the date of the valid period, the final two di
gits indicate the time (valid from 18Z on the 9
th to 24Z on the 10th).
In U.S. METAR: COR rected ob; or AUTO mated ob for automated re
port with no human intervention; omitted when observer logs on.COR
15005KT Wind: 3 digit true-north direction, nearest 10 degrees (or V aRiaBle);
next 2-3 digits for speed and unit, KT (KMH or MPS); as needed, G ust
and maximum speed; 00000KT for calm; for METAR, if direction varies
60 degrees or more, V ariability appended, e.g., 180V 26022015G25KT
5SM Prevailing visibility; in U.S., S tatute M iles & fractions; above 6 miles in
TAF P lus6SM . (Or, 4-digit minimum visibility in meters and as re
quired, lowest value with direction)¾SM
Runway Visual Range: R ; 2-digit runway designator L eft, C enter, or
Right as needed; “/ ”, Minus or Plus in U.S., 4-digit value, F eeT in U.S.,
(usually meters elsewhere); 4-digit value V ariability 4-digit value (and
tendency D own, U p or N o change)R28L/2600FT
HZ Significant present, forecast and recent weather: see table (on back) TSRA
FEW020 Cloud amount, height and type: Sk y Clear 0/8, FEW >0/8-2/8, Sc aTtered
3/8-4/8, B roKeN 5/8-7/8, Ov erCast 8/8; 3-digit height in hundreds of ft;
Towering Cu mulus or C umulonimB us in METAR ; in TAF , only CB .
Vertical V isibility for obscured sky and height “VV004”. More than 1
layer may be reported or forecast. In automated METAR reports only,
CleaR for “clear below 12,000 feet”OVC 010CB
Temperature: degrees Celsius; first 2 digits, temperature “/ ” last 2 digits,
dew-point temperature; M inus for below zero, e.g., M0618/16
Altimeter setting: indicator and 4 digits; in U.S., A -inches and hun
dredths; (Q -hectoPascals, e.g., Q1013)A2992
WS010/31022KT In U.S. TAF , non-convective low-level (≤ 2,000 ft) W ind S hear; 3-digit
height (hundreds of ft); “/ ”; 3-digit wind direction and 2-3 digit wind
speed above the indicated height, and unit, KT
AIM 10/12/17
7−1−61 MeteorologyFIG 7−1−22
Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR) (Back)
Key to Aerodrome Forecast (TAF) and Aviation
Routine Weather Report (METAR) (Back)
In METAR , ReMarK indicator & remarks. For example: S ea- L evel
Pressure in hectoPascals & tenths, as shown: 1004.5 hPa; T emp/dew-
point in tenths °C, as shown: temp. 18.2 °C, dew-point 15.9 °CRMK SLP045
T01820159
FM091930 FroM: changes are expected at: 2-digit date, 2-digit hour, and 2-digit
minute beginning time: indicates significant change. Each FM starts on a
new line, indented 5 spaces
TEMPO
0920/0922TEMPO rary: changes expected for <1 hour and in total, < half of the
period between the 2-digit date and 2-digit hour beginning, and 2-digit
date and 2-digit hour ending time
PROB30
1004/1007PROB ability and 2-digit percent (30 or 40): probable condition in the
period between the 2-digit date & 2-digit hour beginning time, and the
2-digit date and 2-digit hour ending time
BECMG
1013/1015BEC oMinG: change expected in the period between the 2-digit date and
2-digit hour beginning time, and the 2-digit date and 2-digit hour ending
time
Table of Significant Present, Forecast and Recent Weather - Grouped in categories and
used in the order listed below; or as needed in TAF, N o Significant W eather.
Qualifiers
Intensity or Proximity
“-” = Light No sign = Moderate “+” = Heavy
“VC” = Vicinity, but not at aerodrome. In the US METAR, 5 to 10 SM from the point of observation. In the US
TAF, 5 to 10 SM from the center of the runway complex. Elsewhere, within 8000m.
Descriptor
BC – Patches BL – Blowing DR – Drifting FZ – Freezing
MI – Shallow PR – Partial SH – Showers TS – Thunderstorm
Weather Phenomena
Precipitation
DZ – Drizzle GR – Hail GS – Small Hail/Snow Pellets
IC – Ice Crystals PL – Ice Pellets RA – Rain SG – Snow Grains
SN – Snow UP – Unknown Precipitation in automated observations
Obscuration
BR – Mist (≥5/8SM) DU – Widespread Dust FG – Fog (<5/8SM) FU – Smoke
HZ – Haze PY – Spray SA – Sand VA – Volcanic Ash
Other
DS – Dust Storm FC – Funnel Cloud +FC – Tornado or Waterspout
PO – Well developed dust or sand whirls SQ – Squall SS – Sandstorm
- Explanations in parentheses “()” indicate different worldwide practices.
- Ceiling is not specified; defined as the lowest broken or overcast layer, or the vertical visibility.
- NWS TAFs exclude BECMG groups and temperature forecasts, NWS TAFS do not use PROB in the first 9
hours of a TAF; NWS METARs exclude trend forecasts. US Military TAFs include Turbulence and Icing groups.
AIM 10/12/17
7−1−62 Meteorology7−1−31. International Civil Aviation
Organization (ICAO) Weather Formats
The U.S. uses the ICAO world standard for aviation
weather reporting and forecasting. The World
Meteorological Organization’s (WMO) publicationNo. 782 “Aerodrome Reports and Forecasts”
contains the base METAR and TAF code as adopted
by the WMO member countries.
a.Although the METAR code is adopted
worldwide, each country is allowed to make
modifications or exceptions to the code for use intheir particular country, e.g., the U.S. will continue to
use statute miles for visibility, feet for RVR values,
knots for wind speed, and inches of mercury foraltimetry. However, temperature and dew point will
be reported in degrees Celsius. The U.S reports
prevailing visibility rather than lowest sector
visibility. The elements in the body of a METAR
report are separated with a space. The only exceptions
are RVR, temperature, and dew point which are
separated with a solidus (/). When an element does
not occur, or cannot be observed, the preceding spaceand that element are omitted from that particular
report. A METAR report contains the following
sequence of elements in the following order:
1.Type of report.
2.ICAO Station Identifier.
3.Date and time of report.
4.Modifier (as required).
5.Wind.
6.Visibility.
7.Runway Visual Range (RVR).
8.Weather phenomena.
9.Sky conditions.
10.Temperature/dew point group.
11.Altimeter.
12.Remarks (RMK).
b.The following paragraphs describe the ele-
ments in a METAR report.
1. Type of report. There are two types of
report:
(a)Aviation Routine Weather Report
(METAR); and(b)Nonroutine (Special) Aviation Weather
Report (SPECI).
The type of report (METAR or SPECI) will always
appear as the lead element of the report.
2. ICAO Station Identifier. The METAR
code uses ICAO 4 −letter station identifiers. In the
contiguous 48 States, the 3 −letter domestic station
identifier is prefixed with a “K;” i.e., the domestic
identifier for Seattle is SEA while the ICAO identifier
is KSEA. Elsewhere, the first two letters of the ICAO
identifier indicate what region of the world andcountry (or state) the station is in. For Alaska, all
station identifiers start with “PA;” for Hawaii, all
station identifiers start with “PH.” Canadian stationidentifiers start with “CU,” “CW,” “CY ,” and “CZ.”
Mexican station identifiers start with “MM.” The
identifier for the western Caribbean is “M” followed
by the individual country’s letter; i.e., Cuba is “MU;”
Dominican Republic “MD;” the Bahamas “MY .” The
identifier for the eastern Caribbean is “T” followedby the individual country’s letter; i.e., Puerto Rico is
“TJ.” For a complete worldwide listing see ICAO
Document 7910, Location Indicators.
3. Date and Time of Report. The date and
time the observation is taken are transmitted as a
six−digit date/time group appended with Z to denote
Coordinated Universal Time (UTC). The first twodigits are the date followed with two digits for hour
and two digits for minutes.
EXAMPLE −
172345Z (the 17th day of the month at 2345Z)
4. Modifier (As Required). “AUTO” identi-
fies a MET AR/SPECI report as an automated weather
report with no human intervention. If “AUTO” is
shown in the body of the report, the type of sensor
equipment used at the station will be encoded in theremarks section of the report. The absence of
“AUTO” indicates that a report was made manually
by an observer or
that an automated report had human
augmentation/backup. The modifier “COR” indi-
cates a corrected report that is sent out to replace an
earlier report with an error.
NOTE−
There are two types of automated stations, AO1 forautomated weather reporting stations without a precipita-
tion discriminator, and AO2 for automated stations with aprecipitation discriminator. (A pr ecipitation discriminator
can determine the difference between liquid and
frozen/freezing precipit ation). This information appears in
the remarks section of an automated report.
AIM 10/12/17
7−1−63 Meteorology5. Wind. The wind is reported as a five digit
group (six digits if speed is over 99 knots). The first
three digits are the direction the wind is blowing
from, in tens of degrees referenced to true north, or
“VRB” if the direction is variable. The next two digits
is the wind speed in knots, or if over 99 knots, the next
three digits. If the wind is gusty, it is reported as a “G”
after the speed followed by the highest gust reported.
The abbreviation “KT” is appended to denote the use
of knots for wind speed.
EXAMPLE −
13008KT − wind from 130 degrees at 8 knots
08032G45KT − wind from 080 degrees at 32 knots with
gusts to 45 knots
VRB04KT − wind variable in dir ection at 4 knots
00000KT − wind calm
210103G130KT − wind from 210 degrees at 103 knots with
gusts to 130 knots
If the wind direction is variable by 60 degrees or more and
the speed is greater than 6 knots, a variable groupconsisting of the extremes of the wind direction separatedby a “v” will follow the prevailing wind group.32012G22KT 280V350
(a) Peak Wind. Whenever the peak wind
exceeds 25 knots “PK WND” will be included in
Remarks, e.g., PK WND 28045/1955 “Peak wind two
eight zero at four five occurred at one niner five five.”
If the hour can be inferred from the report time, only
the minutes will be appended, e.g., PK WND
34050/38 “Peak wind three four zero at five zerooccurred at three eight past the hour.”
(b) Wind shift. Whenever a wind shift
occurs, “WSHFT” will be included in remarks
followed by the time the wind shift began, e.g.,WSHFT 30 FROPA “Wind shift at three zero due to
frontal passage.”
6. Visibility. Prevailing visibility is reported in
statute miles with “SM” appended to it.
EXAMPLE −
7SM − seven statute miles
15SM − fifteen statute miles
1/2SM − one−half statute mile
(a) Tower/surface visibility. If either visi-
bility (tower or surface) is below four statute miles,the lesser of the two will be reported in the body of the
report; the greater will be reported in remarks.
(b) Automated visibility. ASOS/AWSS
visibility stations will show visibility 10 or greater
than 10 miles as “10SM.” AWOS visibility stations
will show visibility less than 1/4 statute mile as
“M1/4SM” and visibility 10 or greater than 10 miles
as “10SM.”
NOTE−
Automated sites that are augmented by human observer to
meet service level r equir ements can report 0, 1/16 SM, and
1/8 SM visibility increments.
(c) Variable visibility. Variable visibility is
shown in remarks (when rapid increase or decrease
by 1/2 statute mile or more and the average prevailing
visibility is less than three miles) e.g., VIS 1V2
“visibility variable between one and two.”
(d) Sector visibility. Sector visibility is
shown in remarks when it differs from the prevailing
visibility, and either the prevailing or sector visibility
is less than three miles.
EXAMPLE −
VIS N2 − visibility north two
7. Runway Visual Range (When Reported).
“R” identifies the group followed by the runway
heading (and parallel runway designator, if needed)“/” and the visual range in feet (meters in other
countries) followed with “FT” (feet is not spoken).
(a) Variability Values. When RVR varies
(by more than on reportable value), the lowest and
highest values are shown with “V” between them.
(b) Maximum/Minimum Range. “P” indi-
cates an observed RVR is above the maximum value
for this system (spoken as “more than”). “M”
indicates an observed RVR is below the minimum
value w hich can be determined by the system (spoken
as “less than”).
EXAMPLE −
R32L/1200FT − runway thr ee two left R −V−R one thousand
two hundred.
R27R/M1000V4000FT − runway two seven right R −V−R
variable from less than one thousand to four thousand.
AIM 10/12/17
7−1−64 Meteorology8. Weather Phenomena. The weather as
reported in the METAR code represents a significant
change in the way weather is currently reported. In
METAR, weather is reported in the format:
Intensity/Proximity/Descriptor/Precipitation/
Obstruction to visibility/Other
NOTE−
The “/” above and in the following descriptions (except as
the separator between the temperature and dew point) are
for separation purposes in this publication and do notappear in the actual METARs.
(a) Intensity applies only to the first type of
precipitation reported. A “ −” denotes light, no symbol
denotes moderate, and a “+” denotes heavy.
(b) Proximity applies to and reported only
for weather occurring in the vicinity of the airport
(between 5 and 10 miles of the point(s) of
observation). It is denoted by the letters “VC.”
(Intensity and “VC” will not appear together in the
weather group).
(c) Descriptor. These eight descriptors ap-
ply to the precipitation or obstructions to visibility:
TS thunderstorm ...........
DR low drifting ...........
SH showers ...........
MI shallow ...........
FZ freezing ...........
BC patches ...........
BL blowing ...........
PR partial ...........
NOTE−
Although “TS” and “SH” are used with precipitation and
may be preceded with an intensity symbol, the intensity still
applies to the precipitation, not the descriptor.
(d) Precipitation. There are nine types of
precipitation in the METAR code:
RA rain ..........
DZ drizzle ..........
SN snow ..........
GR hail (1/4” or greater) ..........
GS small hail/snow pellets ..........
PL ice pellets ..........
SG snow grains ..........
IC ice crystals (diamond dust) ...........
UP unknown precipitation ..........
(automated stations only)(e) Obstructions to visibility. There are
eight types of obscuration phenomena in the METAR
code (obscurations are any phenomena in the
atmosphere, other than precipitation, that reduce
horizontal visibility):
FG fog (vsby less than 5/8 mile) ..........
HZ haze..........
FU smoke ..........
PY spray ..........
BR mist (vsby 5/8 − 6 miles) ..........
SA sand ..........
DU dust ..........
VA volcanic ash ..........
NOTE−
Fog (FG) is observed or for ecast only when the visibility is
less than five −eighths of mile, otherwise mist (BR) is
observed or forecast.
(f) Other. There are five categories of other
weather phenomena which are reported when theyoccur:
SQ squall ...........
SS sandstorm ...........
DS duststorm ...........
PO dust/sand whirls ..........
FC funnel cloud ...........
+FC tornado/waterspout .........
Examples:
TSRA thunderstorm with moderate .........
rain
+SN heavy snow ..........
−RA FG light rain and fog .......
BRHZ mist and haze ........
(visibility
5/8mile or greater)
FZDZ freezing drizzle .........
VCSH rain shower in the vicinity ........
+SHRASNPL heavy rain showers, snow,..
ice pellets (intensityindicator refers to the
predominant rain)
9. Sky Condition. The sky condition as
reported in METAR represents a significant changefrom the way sky condition is currently reported. In
METAR, sky condition is reported in the format:
Amount/Height/(Type) or Indefinite Ceiling/Height
AIM 10/12/17
7−1−65 Meteorology(a) Amount. The amount of sky cover is
reported in eighths of sky cover, using the
contractions:
SKC clear (no clouds) .........
FEW >0 to 2/8 ........
SCT scattered (3/8s to 4/8s of .........
clouds)
BKN broken (5/8s to 7/8s of clouds) .........
OVC overcast (8/8s clouds) .........
CB Cumulonimbus when present ..........
TCU Towering cumulus when .........
present
NOTE−
1.“SKC” will be r eported at manual stations. “CLR” will
be used at automated stations when no clouds below12,000 feet are reported.
2.A ceiling layer is not designated in the METAR code.
For aviation purposes, the ceiling is the lowest broken orovercast layer, or vertical visibility into an obscuration.
Also there is no provision for reporting thin layers in the
METAR code. When clouds are thin, that layer must bereported as if it were opaque.
(b) Height. Cloud bases are reported with
three digits in hundreds of feet above ground level
(AGL). (Clouds above 12,000 feet cannot be reported
by an automated station).
(c) (Type). If Towering Cumulus Clouds
(TCU) or Cumulonimbus Clouds (CB) are present,
they are reported after the height which represents
their base.
EXAMPLE −
(Reported as) SCT025TCU BKN080 BKN250 (spoken as)
“TWO THOUSAND FIVE HUNDRED SCATTEREDTOWERING CUMULUS, CEILING EIGHT THOUSAND
BROKEN, TWO FIVE THOUSAND BROKEN.”
(Reported as) SCT008 OVC012CB (spoken as) “EIGHT
HUNDRED SCATTERED CEILING ONE THOUSANDTWO HUNDRED OVERCAST CUMULONIMBUSCLOUDS.”
(d) Vertical Visibility (indefinite ceiling
height). The height into an indefinite ceiling is
preceded by “VV” and followed by three digits
indicating the vertical visibility in hundreds of feet.
This layer indicates total obscuration .
EXAMPLE −
1/8 SM FG VV006 − visibility one eighth, fog, indefinite
ceiling six hundred.(e) Obscurations are reported when the sky
is partially obscured by a ground −based phenomena
by indicating the amount of obscuration as FEW,
SCT, BKN followed by three zeros (000). In remarks,
the obscuring phenomenon precedes the amount ofobscuration and three zeros.
EXAMPLE −
BKN000 (in body) “sky partially obscured” ........
FU BKN000 (in remarks) “smoke obscuring five − ...
to seven−eighths of the
sky”
(f)When sky conditions include a layer aloft,
other than clouds, such as smoke or haze the type of
phenomena, sky cover and height are shown inremarks.
EXAMPLE −
BKN020 (in body) “ceiling two thousand ........
broken”
RMK FU BKN020 “broken layer of smoke ........
aloft, based at two thousand”
(g) Variable ceiling. When a ceiling is
below three thousand and is variable, the remark“CIG” will be shown followed with the lowest and
highest ceiling heights separated by a “V .”
EXAMPLE −
CIG 005V010 “ceiling variable ............
between five hundred andone thousand”
(h) Second site sensor. When an automated
station uses meteorological discontinuity sensors,remarks will be shown to identify site specific sky
conditions which differ and are lower than conditions
reported in the body.
EXAMPLE −
CIG 020 RY11 “ceiling two thousand at ...........
runway one one”
(i) Variable cloud layer. When a layer is
varying in sky cover, remarks will show thevariability range. If there is more than one cloud
layer, the variable layer will be identified by
including the layer height.
EXAMPLE −
SCT V BKN “scattered layer variable to .............
broken”
BKN025 V OVC “broken layer at .........
two thousand five hundredvariable to overcast”
AIM 10/12/17
7−1−66 Meteorology(j) Significant clouds. When significant
clouds are observed, they are shown in remarks,
along with the specified information as shown below:
(1)Cumulonimbus (CB), or Cumulonim-
bus Mammatus (CBMAM), distance (if known),
direction from the station, and direction ofmovement, if known. If the clouds are beyond
10 miles from the airport, DSNT will indicate
distance.
EXAMPLE −
CB W MOV E “cumulonimbus west moving .......
east”
CBMAM DSNT S “cumulonimbus mammatus ....
distant south”
(2)Towering Cumulus (TCU), location, (if
known), or direction from the station.
EXAMPLE −
TCU OHD “towering cumulus overhead” .........
TCU W “towering cumulus west” ............
(3)Altocumulus Castellanus (ACC), Stra-
tocumulus Standing Lenticular (SCSL),Altocumulus Standing Lenticular (ACSL), Cirrocu-
mulus Standing Lenticular (CCSL) or rotor clouds,
describing the clouds (if needed) and the directionfrom the station.
EXAMPLE −
ACC W “altocumulus castellanus west” .............
ACSL SW −S “standing lenticular .........
altocumulus southwestthrough south”
APRNT ROTOR CLD S “apparent rotor cloud south”
CCSL OVR MT E “standing lenticular .....
cirrocumulus over the mountains east”
10. Temperature/Dew Point. Temperature
and dew point are reported in two, two-digit groupsin degrees Celsius, separated by a solidus (“/”).
Temperatures below zero are prefixed with an “M.”
If the temperature is available but the dew point ismissing, the temperature is shown followed by a
solidus. If the temperature is missing, the group is
omitted from the report.
EXAMPLE −
15/08 “temperature one five, ..............
dew point 8”
00/M02 “temperature zero, ............
dew point minus 2”M05/ “temperature minus five, ...............
dew point missing”
11. Altimeter. Altimeter settings are reported
in a four-digit format in inches of mercury prefixedwith an “A” to denote the units of pressure.
EXAMPLE −
A2995 − “Altimeter two niner niner five”
12. Remarks. Remarks will be included in all
observations, when appropriate. The contraction
“RMK” denotes the start of the remarks section of aMETAR report.
Except for precipitation, phenomena located within
5 statute miles of the point of observation will bereported as at the station. Phenomena between 5 and
10 statute miles will be reported in the vicinity, “VC.”
Precipitation not occurring at the point of observationbut within 10 statute miles is also reported as in the
vicinity, “VC.” Phenomena beyond 10 statute miles
will be shown as distant, “DSNT.” Distances are instatute miles except for automated lightning remarks
which are in nautical miles. Movement of clouds or
weather will be indicated by the direction towardwhich the phenomena is moving.
(a)There are two categories of remarks:
(1)Automated, manual, and plain
language.
(2)Additive and automated maintenance
data.
(b) Automated, Manual, and Plain Lan-
guage. This group of remarks may be generated
from either manual or automated weather reporting
stations and generally elaborate on parametersreported in the body of the report. (Plain language
remarks are only provided by manual stations).
(1)V olcanic eruptions.
(2)Tornado, Funnel Cloud, Waterspout.
(3)Station Type (AO1 or AO2).
(4)PK WND.
(5)WSHFT (FROPA).
(6)TWR VIS or SFC VIS.
(7)VRB VIS.
(8)Sector VIS.
(9)VIS @ 2
nd Site.
AIM 10/12/17
7−1−67 Meteorology(10) Lightning. When lightning is observed
at a manual location, the frequency and location is
reported.
When cloud −to−ground lightning is detected by an
automated lightning detection system, such as
ALDARS:
[a]Within 5 nautical miles (NM) of the
Airport Reference Point (ARP), it will be reported as
“TS” in the body of the report with no remark;
[b]Between 5 and 10 NM of the ARP, it
will be reported as “VCTS” in the body of the report
with no remark;
[c]Beyond 10 but less than 30 NM of the
ARP, it will be reported in remarks as “DSNT”
followed by the direction from the ARP.
EXAMPLE −
LTG DSNT W or LTG DSNT ALQDS
(11) Beginning/Ending of Precipitation/
TSTMS.
(12) TSTM Location MVMT.
(13) Hailstone Size (GR).
(14) Virga.
(15) VRB CIG (height).
(16) Obscuration.
(17) VRB Sky Condition.
(18) Significant Cloud Types.
(19) Ceiling Height 2nd Location.
(20) PRESFR PRESRR.
(21) Sea−Level Pressure.
(22) ACFT Mishap (not transmitted).
(23) NOSPECI.
(24) SNINCR.
(25) Other SIG Info.
(c) Additive and Automated Maintenance
Data.
(1)Hourly Precipitation.
(2)3− and 6−Hour Precipitation Amount.
(3)24−Hour Precipitation.
(4)Snow Depth on Ground.(5)Water Equivalent of Snow.
(6)Cloud Type.
(7)Duration of Sunshine.
(8)Hourly Temperature/Dew Point
(Tenths).
(9)6−Hour Maximum Temperature.
(10) 6−Hour Minimum Temperature.
(11) 24−Hour Maximum/Minimum
Temperature.
(12) Pressure Tendency.
(13) Sensor Status.
PWINO
FZRANOTSNO
RVRNO
PNOVISNO
Examples of METAR reports and explanation:
METAR KBNA 281250Z 33018KT 290V360
1/2SM R31/2700FT SN BLSN FG VV008 00/M03
A2991 RMK RAE42SNB42
METAR aviation routine weather ......
report
KBNA Nashville, TN ........
281250Z date 28
th, time 1250 UTC ......
(no modifier) This is a manually generated..
report, due to the absence of
“AUTO” and “AO1 or AO2”in remarks
33018KT wind three three zero at one .....
eight
290V360 wind variable between ......
two nine zero and three six
zero
1/2SM visibility one half ........
R31/2700FT Runway three one RVR two...
thousand seven hundred
SN moderate snow ...........
BLSN FG visibility obscured by .....
blowing snow and fog
VV008 indefinite ceiling eight .......
hundred
00/M03 temperature zero, dew point .......
minus three
A2991 altimeter two niner niner one ........
RMK remarks ........
AIM 10/12/17
7−1−68 MeteorologyRAE42 rain ended at four two .......
SNB42 snow began at four two .......
METAR KSFO 041453Z AUTO VRB02KT 3SM
BR CLR 15/12 A3012 RMK AO2
METAR aviation routine weather ......
report
KSFO San Francisco, CA ........
041453Z date 4th, time 1453 UTC ......
AUTO fully automated; no human .......
intervention
VRB02KT wind variable at two ....
3SM visibility three .........
BR visibility obscured by mist ..........
CLR no clouds below one two .........
thousand
15/12 temperature one five, dew .........
point one two
A3012 altimeter three zero one two ........
RMK remarks ........
AO2 this automated station has a .........
weather discriminator (for
precipitation)
SPECI KCVG 152224Z 28024G36KT 3/4SM
+TSRA BKN008 OVC020CB 28/23 A3000 RMKTSRAB24 TS W MOV E
SPECI (nonroutine) aviation special .......
weather report
KCVG Cincinnati, OH .......
152228Z date 15
th, time 2228 UTC ......
(no modifier) This is a manually generated..
report due to the absence of
“AUTO” and “AO1 or AO2”in remarks
28024G36KT wind two eight zero at ..
two four gusts three six
3/4SM visibility three fourths ........
+TSRA thunderstorms, heavy rain .......
BKN008 ceiling eight hundred broken
OVC020CB two thousand overcast...
cumulonimbus clouds
28/23 temperature two eight, .........
dew point two three
A3000 altimeter three zero zero zero ........
RMK remarks ........
TSRAB24 thunderstorm and rain began .....
at two fourTS W MOV E thunderstorm west moving
east
c. Aerodrome Forecast (TAF). A concise state-
ment of the expected meteorological conditions at an
airport during a specified period. At most locations,
TAFs have a 24 hour forecast period. However, TAFs
for some locations have a 30 hour forecast period.These forecast periods may be shorter in the case of
an amended TAF. TAFs use the same codes as
METAR weather reports. They are scheduled four
times daily for 24 −hour periods beginning at 0000Z,
0600Z, 1200Z, and 1800Z.
Forecast times in the TAF are depicted in two ways.
The first is a 6 −digit number to indicate a specific
point in time, consisting of a two −digit date,
two−digit hour, and two −digit minute (such as
issuance time or FM). The second is a pair of
four−digit numbers separated by a “/” to indicate a
beginning and end for a period of time. In this case,
each four−digit pair consists of a two −digit date and
a two−digit hour.
TAFs are issued in the following format:
TYPE OF REPORT/ICAO ST ATION IDENTIFIER/
DATE AND TIME OF ORIGIN/V ALID PERIOD
DATE AND TIME/FORECAST METEOROLOG-ICAL CONDITIONS
NOTE−
The “/” above and in the following descriptions are forseparation purposes in this publication and do not appear
in the actual TAFs.
TAF KORD 051130Z 0512/0618 14008KT 5SM BR
BKN030
TEMPO 0513/0516 1 1/2SM BR
FM051600 16010KT P6SM SKCFM052300 20013G20KT 4SM SHRA OVC020
PROB40 0600/0606 2SM TSRA OVC008CB
BECMG 0606/0608 21015KT P6SM NSW
SCT040
TAF format observed in the above example:TAF = type of reportKORD = ICAO station identifier051130Z = date and time of origin (issuance time)0512/0618 = valid period date and times14008KT 5SM BR BKN030 = forecast meteorolo-
gical conditions
Explanation of TAF elements:
AIM 10/12/17
7−1−69 Meteorology1. Type of Report. There are two types of TAF
issuances, a routine forecast issuance (TAF) and an
amended forecast (TAF AMD). An amended TAF is
issued when the current TAF no longer adequately
describes the on-going weather or the forecaster feels
the TAF is not representative of the current or
expected weather. Corrected (COR) or delayed
(RTD) TAFs are identified only in the communica-tions header which precedes the actual forecasts.
2. ICAO Station Identifier. The TAF code
uses ICAO 4 −letter location identifiers as described
in the METAR section.
3. Date and Time of Origin. This element is
the date and time the forecast is actually prepared.
The format is a two −digit date and four −digit time
followed, without a space, by the letter “Z.”
4. Valid Period Date and Time. The UTC
valid period of the forecast consists of two four −digit
sets, separated by a “/”. The first four −digit set is a
two−digit date followed by the two −digit beginning
hour, and the second four −digit set is a two −digit date
followed by the two −digit ending hour. Although
most airports have a 24 −hour TAF, a select number of
airports have a 30 −hour TAF. In the case of an
amended forecast, or a forecast which is corrected or
delayed, the valid period may be for less than 24
hours. Where an airport or terminal operates on apart−time basis (less than 24 hours/day), the TAFs
issued for those locations will have the abbreviated
statement “AMD NOT SKED” added to the end ofthe forecasts. The time observations are scheduled to
end and/or resume will be indicated by expanding the
AMD NOT SKED statement. Expanded statements
will include:
(a)Observation ending time (AFT DDH-
Hmm; for example, AFT 120200)
(b)Scheduled observations resumption time
(TIL DDHHmm; for example, TIL 171200Z) or
(c)Period of observation unavailability
(DDHH/DDHH); for example, 2502/2512).
5. Forecast Meteorological Conditions. This
is the body of the TAF. The basic format is:
WIND/VISIBILITY/WEATHER/SKY
CONDITION/OPTIONAL DATA (WIND SHEAR)
The wind, visibility, and sky condition elements are
always included in the initial time group of the
forecast. Weather is included only if significant toaviation. If a significant, lasting change in any of the
elements is expected during the valid period, a new
time period with the changes is included. It should be
noted that with the exception of a “FM” group the
new time period will include only those elementswhich are expected to change, i.e., if a lowering of the
visibility is expected but the wind is expected to
remain the same, the new time period reflecting thelower visibility would not include a forecast wind.
The forecast wind would remain the same as in the
previous time period. Any temporary conditionsexpected during a specific time period are included
with that time period. The following describes the
elements in the above format.
(a) Wind. This five (or six) digit group
includes the expected wind direction (first 3 digits)
and speed (last 2 digits or 3 digits if 100 knots orgreater). The contraction “KT” follows to denote the
units of wind speed. W ind gusts are noted by the letter
“G” appended to the wind speed followed by the
highest expected gust. A variable wind direction is
noted by “VRB” where the three digit directionusually appears. A calm wind (3 knots or less) is
forecast as “00000KT.”
EXAMPLE −
18010KT wind one eight zero at one zero (wind is .....
blowing from 180).
35012G20KT wind three five zero at one two gust two ..
zero.
(b) Visibility. The expected prevailing visi-
bility up to and including 6 miles is forecast in statute
miles, including fractions of miles, followed by “SM”
to note the units of measure. Expected visibilities
greater than 6 miles are forecast as P6SM (plus
six statute miles).
EXAMPLE −
1/2SM − visibility one −half
4SM − visibility four
P6SM − visibility mor e than six
(c) Weather Phenomena. The expected
weather phenomena is coded in TAF reports using the
same format, qualifiers, and phenomena contractions
as METAR reports (except UP). Obscurations to
vision will be forecast whenever the prevailingvisibility is forecast to be 6 statute miles or less. If no
significant weather is expected to occur during a
specific time period in the forecast, the weatherphenomena group is omitted for that time period. If,
after a time period in which significant weather
phenomena has been forecast, a change to a forecast
AIM 10/12/17
7−1−70 Meteorologyof no significant weather phenomena occurs, the
contraction NSW (No Significant Weather) will
appear as the weather group in the new time period.
(NSW is included only in TEMPO groups).
NOTE−
It is very important that pilots understand that NSW only
refers to weather phenomena, i.e., rain, snow, drizzle, etc.
Omitted conditions, such as sky conditions, visibility,winds, etc., are carried over from the previous time group.
(d) Sky Condition. TAF sky condition
forecasts use the METAR format described in the
METAR section. Cumulonimbus clouds (CB) are the
only cloud type forecast in TAFs. When clear skiesare forecast, the contraction “SKC” will always be
used. The contraction “CLR” is never used in the
TAF. When the sky is obscured due to asurface−based phenomenon, vertical visibility (VV)
into the obscuration is forecast. The format for
vertical visibility is “VV” followed by a three −digit
height in hundreds of feet.
NOTE−
As in METAR, ceiling layers are not designated in the TAF
code. For aviation purposes, the ceiling is the lowest
broken or overcast layer or vertical visibility into acomplete obscuration.
SKC “sky clear” ..............
SCT005 BKN025CB “five hundred scattered,.
ceiling two thousand
five hundred broken cumulonimbus clouds”
VV008 “indefinite ceiling ............
eight hundred”
(e) Optional Data (Wind Shear). Wind
shear is the forecast of nonconvective low level winds
(up to 2,000 feet). The forecast includes the letters“WS” followed by the height of the wind shear, the
wind direction and wind speed at the indicated height
and the ending letters “KT” (knots). Height is givenin hundreds of feet (AGL) up to and including
2,000 feet. Wind shear is encoded with the
contraction “WS,” followed by a three −digit height,
slant character “/,” and winds at the height indicated
in the same format as surface winds. The wind shear
element is omitted if not expected to occur.
WS010/18040KT − “LOW LEVEL WIND SHEAR
AT ONE THOUSAND, WIND ONE EIGHT ZERO
AT FOUR ZERO”
d. Probability Forecast. The probability or
chance of thunderstorms or other precipitation eventsoccurring, along with associated weather conditions
(wind, visibility, and sky conditions). The PROB30
group is used when the occurrence of thunderstorms
or precipitation is 30 −39% and the PROB40 group is
used when the occurrence of thunderstorms orprecipitation is 40 −49%. This is followed by two
four−digit groups separated by a “/”, giving the
beginning date and hour, and the ending date and hour
of the time period during which the thunderstorms or
precipitation are expected.
NOTE−
NWS does not use PROB 40 in the TAF . However U.S.Military generated TAFS may include PROB40. PROB30will not be shown during the first nine hours of a NWS
forecast.
EXAMPLE −
PROB40 2221/2302
1/2SM +TSRA “chance between
2100Z and 0200Z of
visibility one −half
statute mile in thunderstorms andheavy rain.”
PROB30 3010/3014 1SM RASN “chance between .
1000Z and 1400Z of
visibility one statutemile in mixed rainand snow.”
e. Forecast Change Indicators. The following
change indicators are used when either a rapid,gradual, or temporary change is expected in some or
all of the forecast meteorological conditions. Each
change indicator marks a time group within the TAFreport.
1.From (FM) group. The FM group is used
when a rapid change, usually occurring in less thanone hour, in prevailing conditions is expected.
Typically, a rapid change of prevailing conditions to
more or less a completely new set of prevailingconditions is associated with a synoptic feature
passing through the terminal area (cold or warm
frontal passage). Appended to the “FM” indicator isthe six−digit date, hour, and minute the change is
expected to begin and continues until the next change
group or until the end of the current forecast. A “FM”
group will mark the beginning of a new line in a TAF
report (indented 5 spaces). Each “FM” group
contains all the required elements −wind, visibility,
weather, and sky condition. Weather will be omitted
in “FM” groups when it is not significant to aviation.
FM groups will not include the contraction NSW.
AIM 10/12/17
7−1−71 MeteorologyEXAMPLE −
FM210100 14010KT P6SM SKC − “after 0100Z on the
21st, wind one four zero at one zero, visibility more than six,
sky clear.”
2.Becoming (BECMG) group. The BECMG
group is used when a gradual change in conditions is
expected over a longer time period, usually twohours. The time period when the change is expected
is two four −digit groups separated by a “/”, with the
beginning date and hour, and ending date and hour of
the change period which follows the BECMG
indicator. The gradual change will occur at an
unspecified time within this time period. Only thechanging forecast meteorological conditions are
included in BECMG groups. The omitted conditions
are carried over from the previous time group.
NOTE−
The NWS does not use BECMG in the TAF .
EXAMPLE −
OVC012 BECMG 0114/0116 BKN020 − “ceiling one
thousand two hundred overcast. Then a gradual change
to ceiling two thousand broken between 1400Z on the 1st
and 1600Z on the 1st.”3.Temporary (TEMPO) group. The TEMPO
group is used for any conditions in wind, visibility,
weather, or sky condition which are expected to last
for generally less than an hour at a time (occasional),
and are expected to occur during less than half thetime period. The TEMPO indicator is followed by
two four−digit groups separated by a “/”. The first
four digit group gives the beginning date and hour,and the second four digit group gives the ending date
and hour of the time period during which the
temporary conditions are expected. Only thechanging forecast meteorological conditions are
included in TEMPO groups. The omitted conditions
are carried over from the previous time group.
EXAMPLE −
1.SCT030 TEMPO 0519/0523 BKN030 − “three
thousand scattered with occasional ceilings three thousand
broken between 1900Z on the 5th and 2300Z on the 5th.”
2.4SM HZ TEMPO 1900/1906 2SM BR HZ − “visibility
four in haze with occasional visibility two in mist and haze
between 0000Z on the 19th and 0600Z on the 19th.”
AIM 10/12/17
7−2−1 Altimeter Setting ProceduresSection 2. Altimeter Setting Procedures
7−2−1. General
a.The accuracy of aircraft altimeters is subject to
the following factors:
1.Nonstandard temperatures of the atmosphere.
2.Nonstandard atmospheric pressure.
3.Aircraft static pressure systems (position
error); and
4.Instrument error.
b.EXTREME CAUTION SHOULD BE EXER-
CISED WHEN FLYING IN PROXIMITY TO
OBSTRUCTIONS OR TERRAIN IN LOW TEM-
PERATURES AND PRESSURES. This is especially
true in extremely cold temperatures that cause a large
differential between the Standard Day temperature
and actual temperature. This circumstance can causeserious errors that result in the aircraft being
significantly lower than the indicated altitude.
NOTE−
Standard temperature at sea level is 15 degrees Celsius
(59 degrees Fahrenheit). The temperature gradient from
sea level is minus 2 degrees Celsius (3.6 degreesFahrenheit) per 1,000 feet. Pilots should apply corr ections
for static pressure systems and/or instruments, ifappreciable errors exist.
c.The adoption of a standard altimeter setting at
the higher altitudes eliminates station barometer
errors, some altimeter instrument errors, and errors
caused by altimeter settings derived from differentgeographical sources.
7−2−2. Procedures
The cruising altitude or flight level of aircraft must be
maintained by reference to an altimeter which must
be set, when operating:
a. Below 18,000 feet MSL.
1. When the barometric pressure is
31.00 inches Hg. or less. To the current reported
altimeter setting of a station along the route and
within 100 NM of the aircraft, or if there is no station
within this area, the current reported altimeter setting
of an appropriate available station. When an aircraftis en route on an instrument flight plan, air traffic
controllers will furnish this information to the pilot at
least once while the aircraft is in the controllers area
of jurisdiction. In the case of an aircraft not equipped
with a radio, set to the elevation of the departureairport or use an appropriate altimeter setting
available prior to departure.
2. When the barometric pressure exceeds
31.00 inches Hg. The following procedures will be
placed in effect by NOTAM defining the geographicarea affected:
(a) For all aircraft. Set 31.00 inches for en
route operations below 18,000 feet MSL. Maintain
this setting until beyond the affected area or untilreaching final approach segment. At the beginning of
the final approach segment, the current altimeter
setting will be set, if possible. If not possible,31.00 inches will remain set throughout the ap-
proach. Aircraft on departure or missed approach will
set 31.00 inches prior to reaching any mandatory/crossing altitude or 1,500 feet AGL, whichever is
lower. (Air traffic control will issue actual altimeter
settings and advise pilots to set 31.00 inches in theiraltimeters for en route operations below 18,000 feet
MSL in affected areas.)
(b)During preflight, barometric altimeters
must be checked for normal operation to the extentpossible.
(c)For aircraft with the capability of setting
the current altimeter setting and operating into
airports with the capability of measuring the current
altimeter setting, no additional restrictions apply.
(d)For aircraft operating VFR, there are no
additional restrictions, however, extra diligence in
flight planning and in operating in these conditions is
essential.
(e)Airports unable to accurately measure
barometric pressures above 31.00 inches of Hg. will
report the barometric pressure as “missing” or “in
excess of 31.00 inches of Hg.” Flight operations toand from those airports are restricted to VFR weather
conditions.
AIM 10/12/17
7−2−2 Altimeter Setting Procedures(f)For aircraft operating IFR and unable to set
the current altimeter setting, the following restric-
tions apply:
(1)To determine the suitability of depar-
ture alternate airports, destination airports, anddestination alternate airports, increase ceiling
requirements by 100 feet and visibility requirements
by
1/4 statute mile for each 1/10 of an inch of Hg., or
any portion thereof, over 31.00 inches. These
adjusted values are then applied in accordance withthe requirements of the applicable operating
regulations and operations specifications.
EXAMPLE −
Destination altimeter is 31.28 inches, ILS DH 250 feet(200−
1/2). When flight planning, add 300 −3/4 to the
weather r equir ements which would become 500 −11/4.
(2)On approach, 31.00 inches will remain
set. Decision height (DH) or minimum descent
altitude must be deemed to have been reached when
the published altitude is displayed on the altimeter.
NOTE−
Although visibility is normally the limiting factor on anapproach, pilots should be aware that when reaching DHthe aircraft will be higher than indicated. Using theexample above the aircraft would be approximately
300 feet higher.
(3)These restrictions do not apply to
authorized Category II and III ILS operations nor do
they apply to certificate holders using approved QFE
altimetry systems.
(g)The FAA Regional Flight Standards
Division Manager of the af fected area is authorized to
approve temporary waivers to permit emergency
resupply or emergency medical service operation.b. At or above 18,000 feet MSL. To 29.92 inch-
es of mercury (standard setting). The lowest usable
flight level is determined by the atmospheric pressure
in the area of operation as shown in TBL 7 −2−1.
TBL 7−2−1
Lowest Usable Flight Level
Altimeter Setting
(Current Reported)Lowest Usable
Flight Level
29.92 or higher 180
29.91 to 29.42 185
29.41 to 28.92 190
28.91 to 28.42 195
28.41 to 27.92 200
c.Where the minimum altitude, as prescribed in
14 CFR Section 91.159 and 14 CFR Section 91.177,is above 18,000 feet MSL, the lowest usable flight
level must be the flight level equivalent of the
minimum altitude plus the number of feet specified in
TBL 7−2−2.
TBL 7−2−2
Lowest Flight Level Correction Factor
Altimeter Setting Correction Factor
29.92 or higher none
29.91 to 29.42 500 feet
29.41 to 28.92 1000 feet
28.91 to 28.42 1500 feet
28.41 to 27.92 2000 feet
27.91 to 27.42 2500 feet
EXAMPLE −
The minimum safe altitude of a route is 19,000 feet MSL
and the altimeter setting is reported between 29.92 and29.42 inches of mercury, the lowest usable flight level will
be 195, which is the flight level equivalent of 19,500 feetMSL (minimum altitude plus 500 feet).
AIM 10/12/17
7−2−3 Altimeter Setting Procedures7−2−3. Altimeter Errors
a.Most pressure altimeters are subject to
mechanical, elastic, temperature, and installationerrors. (Detailed information regarding the use of
pressure altimeters is found in the Instrument Flying
Handbook, Chapter IV .) Although manufacturingand installation specifications, as well as the periodic
test and inspections required by regulations (14 CFR
Part 43, Appendix E), act to reduce these errors, anyscale error may be observed in the following manner:
1.Set the current reported altimeter setting on
the altimeter setting scale.
2.Altimeter should now read field elevation if
you are located on the same reference level used toestablish the altimeter setting.
3.Note the variation between the known field
elevation and the altimeter indication. If this variation
is in the order of plus or minus 75 feet, the accuracy
of the altimeter is questionable and the problem
should be referred to an appropriately rated repair
station for evaluation and possible correction.
b.Once in flight, it is very important to obtain
frequently current altimeter settings en route. If you
do not reset your altimeter when flying from an area
of high pressure into an area of low pressure, your
aircraft will be closer to the surface than your
altimeter indicates. An inch error in the altimeter
setting equals 1,000 feet of altitude. To quote an oldsaying: “GOING FROM A HIGH TO A LOW,
LOOK OUT BELOW .”
c.Temperature also has an effect on the accuracy
of altimeters and your altitude. The crucial values to
consider are standard temperature versus the ambient
(at altitude) temperature and the elevation above the
altitude setting reporting source. It is these
“differences” that cause the error in indicatedaltitude. When the column of air is warmer than
standard, you are higher than your altimeter indicates.
Subsequently, when the column of air is colder thanstandard, you are lower than indicated. It is the
magnitude of these “differences” that determine the
magnitude of the error. When flying into a cooler air
mass while maintaining a constant indicated altitude,
you are losing true altitude. However, flying into a
cooler air mass does not necessarily mean you will be
lower than indicated if the difference is still on the
plus side. For example, while flying at 10,000 feet
(where STANDARD temperature is −5 degreesCelsius (C)), the outside air temperature cools from
+5 degrees C to 0 degrees C, the temperature error
will nevertheless cause the aircraft to be HIGHER
than indicated. It is the extreme “cold” dif ference that
normally would be of concern to the pilot. Also, when
flying in cold conditions over mountainous terrain,
the pilot should exercise caution in flight planning
both in regard to route and altitude to ensure adequate
en route and terminal area terrain clearance.
NOTE−
Non-standard temperatures can result in a change toeffective vertical paths and actual descent rates whileusing aircraft Baro-VNAV equipment for vertical guidance
on final approach segments. A higher than standard
temperature will r esult in a steeper gradient and incr eased
actual descent rate. Indications of these differences areoften not directly related to vertical speed indications.Conversely, a lower than standard temperature will result
in a shallower descent gradient and r educed actual descent
rate. Pilots should consider potential consequences of
these effects on approach minimums, power settings, sight
picture, visual cues, etc., especially for high-altitude orterrain-challenged locations and during low-visibilityconditions.
d.TBL 7−2−3, derived from ICAO formulas,
indicates how much error can exist when operating in
cold temperatures. To use the table, find the reported
temperature in the left column, read across the top
row to locate the height above the airport/reporting
station (i.e., subtract the airport/ reporting elevation
from the intended flight altitude). The intersection of
the column and row is how much lower the aircraft
may actually be as a result of the possible cold
temperature induced error.
e.Pilots are responsible to compensate for cold
temperature altimetry errors when operating into an
airport with any published cold temperature
restriction and a reported airport temperature at or
below the published temperature restriction. Pilots
must ensure compensating aircraft are correcting on
the proper segment or segments of the approach.Manually correct if compensating aircraft system is
inoperable. Pilots manually correcting, are respons-
ible to calculate and apply a cold temperature altitude
correction derived from TBL 7 −2−3 to the affected
approach segment or segments. Pilots must advise the
cold temperature altitude correction to Air TrafficControl (A TC). Pilots are not required to advise ATC
of a cold temperature altitude correction inside of the
final approach fix.
AIM 10/12/17
7−2−4 Altimeter Setting ProceduresTBL 7−2−3
ICAO Cold Temperature Error TableReported Temp /C0095CHeight Above Airport in Feet
200 300 400 500 600 700 800 900 1000 1500 2000 3000 4000 5000
+10 10 10 10 10 20 20 20 20 20 30 40 60 80 90
0 20 20 30 30 40 40 50 50 60 90 120 170 230 280
−10 20 30 40 50 60 70 80 90 100 150 200 290 390 490
−20 30 50 60 70 90 100 120 130 140 210 280 420 570 710
−30 40 60 80 100 120 140 150 170 190 280 380 570 760 950
−40 50 80 100 120 150 170 190 220 240 360 480 720 970 1210
−50 60 90 120 150 180 210 240 270 300 450 590 890 1190 1500
EXAMPLE −
Temperature −10 degrees Celsius, and the aircraft altitude is 1,000 feet above the airport elevation. The chart shows that
the reported curr ent altimeter setting may place the aircraft as much as 100 feet below the altitude indicated by the altimeter .
7−2−4. High Barometric Pressure
a.Cold, dry air masses may produce barometric
pressures in excess of 31.00 inches of Mercury, andmany altimeters do not have an accurate means of
being adjusted for settings of these levels. When the
altimeter cannot be set to the higher pressure setting,
the aircraft actual altitude will be higher than the
altimeter indicates.
REFERENCE −
AIM, Paragraph 7 −2−3 , Altimeter Errors.
b.When the barometric pressure exceeds
31.00 inches, air traffic controllers will issue the
actual altimeter setting, and:
1. En Route/Arrivals. Advise pilots to remain
set on 31.00 inches until reaching the final approach
segment.2. Departures. Advise pilots to set 31.00 inch-
es prior to reaching any mandatory/crossing altitude
or 1,500 feet, whichever is lower.
c.The altimeter error caused by the high pressure
will be in the opposite direction to the error caused by
the cold temperature.
7−2−5. Low Barometric Pressure
When abnormally low barometric pressure condi-
tions occur (below 28.00), flight operations by
aircraft unable to set the actual altimeter setting are
not recommended.
NOTE−
The true altitude of the air craft is lower than the indicated
altitude if the pilot is unable to set the actual altimeter
setting.
AIM 10/12/17
7−3−1 Wake TurbulenceSection 3. Wake Turbulence
7−3−1. General
a.Every aircraft generates a wake while in flight.
Initially, when pilots encountered this wake in flight,
the disturbance was attributed to “prop wash.” It is
known, however, that this disturbance is caused by apair of counter −rotating vortices trailing from the
wing tips. The vortices from larger aircraft pose
problems to encountering aircraft. For instance, thewake of these aircraft can impose rolling moments
exceeding the roll−control authority of the encounter-
ing aircraft. Further, turbulence generated within thevortices can damage aircraft components and
equipment if encountered at close range. The pilot
must learn to envision the location of the vortex wake
generated by larger (transport category) aircraft and
adjust the flight path accordingly.
b.During ground operations and during takeoff,
jet engine blast (thrust stream turbulence) can cause
damage and upsets if encountered at close range.
Exhaust velocity versus distance studies at variousthrust levels have shown a need for light aircraft to
maintain an adequate separation behind large turbojet
aircraft. Pilots of lar ger aircraft should be particularly
careful to consider the effects of their “jet blast” on
other aircraft, vehicles, and maintenance equipment
during ground operations.
7−3−2. Vortex Generation
Lift is generated by the creation of a pressure
differential over the wing surface. The lowest
pressure occurs over the upper wing surface and the
highest pressure under the wing. This pressuredifferential triggers the roll up of the airflow aft of the
wing resulting in swirling air masses trailing
downstream of the wing tips. After the roll up iscompleted, the wake consists of two counter −rotating
cylindrical vortices. (See FIG 7−3−1.) Most of the
energy is within a few feet of the center of each
vortex, but pilots should avoid a region within about
100 feet of the vortex core.FIG 7−3−1
Wake Vortex Generation
7−3−3. Vortex Strength
a.The strength of the vortex is governed by the
weight, speed, and shape of the wing of the generating
aircraft. The vortex characteristics of any given
aircraft can also be changed by extension of flaps orother wing configuring devices as well as by change
in speed. However, as the basic factor is weight, the
vortex strength increases proportionately. Peakvortex tangential speeds exceeding 300 feet per
second have been recorded. The greatest vortex
strength occurs when the generating aircraft is
HEA VY , CLEAN, and SLOW.
b. Induced Roll
1.In rare instances a wake encounter could
cause inflight structural damage of catastrophic
proportions. However , the usual hazard is associated
with induced rolling moments which can exceed the
roll−control authority of the encountering aircraft. In
flight experiments, aircraft have been intentionallyflown directly up trailing vortex cores of larger
aircraft. It was shown that the capability of an aircraft
to counteract the roll imposed by the wake vortex
primarily depends on the wingspan and counter −
control responsiveness of the encountering aircraft.
AIM 10/12/17
7−3−2 Wake Turbulence2.Counter control is usually effective and
induced roll minimal in cases where the wingspan
and ailerons of the encountering aircraft extend
beyond the rotational flow field of the vortex. It is
more difficult for aircraft with short wingspan(relative to the generating aircraft) to counter the
imposed roll induced by vortex flow. Pilots of short
span aircraft, even of the high performance type, must
be especially alert to vortex encounters.
(See FIG 7−3−2.)
FIG 7−3−2
Wake Encounter Counter Control
COUNTER
CONTROL
3.The wake of larger aircraft requires the
respect of all pilots.
7−3−4. Vortex Behavior
a.Trailing vortices have certain behavioral
characteristics which can help a pilot visualize thewake location and thereby take avoidance precau-
tions.
1.An aircraft generates vortices from the
moment it rotates on takeoff to touchdown, since
trailing vortices are a by −product of wing lift. Prior to
takeoff or touchdown pilots should note the rotationor touchdown point of the preceding aircraft. (See
FIG 7−3−3.)
2.The vortex circulation is outward, upward
and around the wing tips when viewed from either
ahead or behind the aircraft. Tests with large aircraft
have shown that the vortices remain spaced a bit less
than a wingspan apart, drifting with the wind, at
altitudes greater than a wingspan from the ground. In
view of this, if persistent vortex turbulence isencountered, a slight change of altitude and lateral
position (preferably upwind) will provide a flight
path clear of the turbulence.
3.Flight tests have shown that the vortices from
larger (transport category) aircraft sink at a rate of
several hundred feet per minute, slowing their
descent and diminishing in strength with time and
distance behind the generating aircraft. Atmospheric
turbulence hastens breakup. Pilots should fly at orabove the preceding aircraft’s flight path, altering
course as necessary to avoid the area behind and
below the generating aircraft. (See FIG 7 −3−4.)
However, vertical separation of 1,000 feet may be
considered safe.
4.When the vortices of larger aircraft sink close
to the ground (within 100 to 200 feet), they tend tomove laterally over the ground at a speed of 2 or
3 knots. (See FIG 7−3−5.)
FIG 7−3−3
Wake Ends/Wake Begins
Touchdown Rotation
Wake Ends Wake Begins
AIM 10/12/17
7−3−3 Wake TurbulenceFIG 7−3−4
Vortex Flow Field
AVOIDAVOIDNominally 500-1000 Ft.Nominally 500-1000 Ft.
Sink Rate
Several Hundred Ft.,/Min.Sink Rate
Several Hundred Ft.,/Min.
FIG 7−3−5
Vortex Movement Near Ground − No Wind
No WindNo Wind3K3K 3K3K
FIG 7−3−6
Vortex Movement Near Ground − with Cross Winds
6K6K
(3K + 3K)(3K + 3K)3K Wind3K Wind
0 (3K - 3K)0 (3K - 3K)
AIM 10/12/17
7−3−4 Wake Turbulence5.There is a small segment of the aviation
community that have become convinced that wake
vortices may “bounce” up to twice their nominal
steady state height. With a 200 −foot span aircraft, the
“bounce” height could reach approximately 200 feetAGL. This conviction is based on a single
unsubstantiated report of an apparent coherent
vortical flow that was seen in the volume scan of aresearch sensor. No one can say what conditions
cause vortex bouncing, how high they bounce, at
what angle they bounce, or how many times a vortex
may bounce. On the other hand, no one can say for
certain that vortices never “bounce.” Test data have
shown that vortices can rise with the air mass in which
they are embedded. Wind shear, particularly, can
cause vortex flow field “tilting.” Also, ambient
thermal lifting and orographic effects (rising terrainor tree lines) can cause a vortex flow field to rise.
Notwithstanding the foregoing, pilots are reminded
that they should be alert at all times for possible wakevortex encounters when conducting approach and
landing operations. The pilot has the ultimate
responsibility for ensuring appropriate separations
and positioning of the aircraft in the terminal area to
avoid the wake turbulence created by a precedingaircraft.
b.A crosswind will decrease the lateral movement
of the upwind vortex and increase the movement of
the downwind vortex. Thus a light wind with a cross
runway component of 1 to 5 knots could result in the
upwind vortex remaining in the touchdown zone for
a period of time and hasten the drift of the downwind
vortex toward another runway. (See FIG 7 −3−6.)
Similarly, a tailwind condition can move the vortices
of the preceding aircraft forward into the touchdown
zone. THE LIGHT QUARTERING TAILWINDREQUIRES MAXIMUM CAUTION. Pilots should
be alert to large aircraft upwind from their approach
and takeoff flight paths. (See FIG 7−3−7.)
FIG 7−3−7
Vortex Movement in Ground Effect − Tailwind
Light Quartering
TailwindLight Quartering
Tailwind
xTail WindTail Wind
Touchdown PointTouchdown Point
AIM 10/12/17
7−3−5 Wake Turbulence7−3−5. Operations Problem Areas
a.A wake encounter can be catastrophic. In 1972
at Fort Worth a DC −9 got too close to a DC −10
(two miles back), rolled, caught a wingtip, and
cartwheeled coming to rest in an inverted position on
the runway. All aboard were killed. Serious and even
fatal GA accidents induced by wake vortices are not
uncommon. However, a wake encounter is notnecessarily hazardous. It can be one or more jolts with
varying severity depending upon the direction of the
encounter, weight of the generating aircraft, size ofthe encountering aircraft, distance from the generat-
ing aircraft, and point of vortex encounter. The
probability of induced roll increases when the
encountering aircraft’s heading is generally aligned
with the flight path of the generating aircraft.
b.A VOID THE AREA BELOW AND BEHIND
THE GENERATING AIRCRAFT, ESPECIALLY
AT LOW ALTITUDE WHERE EVEN A
MOMENTARY W AKE ENCOUNTER COULD BE
HAZARDOUS. This is not easy to do. Some
accidents have occurred even though the pilot of the
trailing aircraft had carefully noted that the aircraft in
front was at a considerably lower altitude. Unfortu-
nately, this does not ensure that the flight path of thelead aircraft will be below that of the trailing aircraft.
c.Pilots should be particularly alert in calm wind
conditions and situations where the vortices could:
1.Remain in the touchdown area.
2.Drift from aircraft operating on a nearby
runway.
3.Sink into the takeoff or landing path from a
crossing runway.
4.Sink into the traffic pattern from other airport
operations.
5.Sink into the flight path of VFR aircraft
operating on the hemispheric altitude 500 feet below.
d.Pilots of all aircraft should visualize the
location of the vortex trail behind larger aircraft and
use proper vortex avoidance procedures to achievesafe operation. It is equally important that pilots of
larger aircraft plan or adjust their flight paths to
minimize vortex exposure to other aircraft.7−3−6. Vortex Avoidance Procedures
a.Under certain conditions, airport traffic control-
lers apply procedures for separating IFR aircraft. If a
pilot accepts a clearance to visually follow a
preceding aircraft, the pilot accepts responsibility for
separation and wake turbulence avoidance. Thecontrollers will also provide to VFR aircraft, with
whom they are in communication and which in the
tower’s opinion may be adversely affected by waketurbulence from a lar ger aircraft, the position, altitude
and direction of flight of larger aircraft followed by
the phrase “CAUTION − WAKE TURBULENCE.”
After issuing the caution for wake turbulence, the
airport traffic controllers generally do not provideadditional information to the following aircraft
unless the airport traffic controllers know the
following aircraft is overtaking the precedingaircraft. WHETHER OR NOT A WARNING OR
INFORMATION HAS BEEN GIVEN, HOWEVER,
THE PILOT IS EXPECTED TO ADJUST AIR-CRAFT OPERATIONS AND FLIGHT PATH AS
NECESSARY TO PRECLUDE SERIOUS WAKE
ENCOUNTERS. When any doubt exists aboutmaintaining safe separation distances between
aircraft during approaches, pilots should ask the
control tower for updates on separation distance andaircraft groundspeed.
b.
The following vortex avoidance procedures are
recommended for the various situations:
1. Landing behind a larger aircraft − same
runway. Stay at or above the larger aircraft’s final
approach flight path −note its touchdown point −land
beyond it.
2. Landing behind a larger aircraft − when
parallel runway is closer than 2,500 feet. Consider
possible drift to your runway. Stay at or above the
larger aircraft’s final approach flight path − note its
touchdown point.
3. Landing behind a larger aircraft − crossing
runway. Cross above the lar ger aircraft’s flight path.
4. Landing behind a departing larger air-
craft− same runway. Note the larger aircraft’s
rotation point − land well prior to rotation point.
5. Landing behind a departing larger air-
craft− crossing runway. Note the larger aircraft’s
rotation point − if past the intersection − continue the
approach− land prior to the intersection. If larger
aircraft rotates prior to the intersection, avoid flight
AIM 10/12/17
7−3−6 Wake Turbulencebelow the larger aircraft’s flight path. Abandon the
approach unless a landing is ensured well before
reaching the intersection.
6. Departing behind a larger aircraft. Note
the larger aircraft’s rotation point and rotate prior to
the larger aircraft’ s rotation point. Continue climbing
above the larger aircraft’s climb path until turning
clear of the larger aircraft’s wake. Avoid subsequent
headings which will cross below and behind a larger
aircraft. Be alert for any critical takeoff situation
which could lead to a vortex encounter.
7. Intersection takeoffs − same runway. Be
alert to adjacent larger aircraft operations, particular-
ly upwind of your runway. If intersection takeoff
clearance is received, avoid subsequent headingwhich will cross below a larger aircraft’s path.
8. Departing or landing after a larger
aircraft executing a low approach, missedapproach, or touch −and−go landing. Because
vortices settle and move laterally near the ground, the
vortex hazard may exist along the runway and in your
flight path after a larger aircraft has executed a low
approach, missed approach, or a touch −and−go
landing, particular in light quartering wind condi-tions. You should ensure that an interval of at least
2 minutes has elapsed before your takeoff or landing.
9. En route VFR (thousand −foot altitude plus
500 feet). Avoid flight below and behind a large
aircraft’s path. If a larger aircraft is observed above on
the same track (meeting or overtaking) adjust yourposition laterally, preferably upwind.
7−3−7. Helicopters
In a slow hover taxi or stationary hover near the
surface, helicopter main rotor(s) generate downwash
producing high velocity outwash vortices to adistance approximately three times the diameter of
the rotor. When rotor downwash hits the surface, the
resulting outwash vortices have behavioral character-
istics similar to wing tip vortices produced by fixed
wing aircraft. However, the vortex circulation is
outward, upward, around, and away from the mainrotor(s) in all directions. Pilots of small aircraft
should avoid operating within three rotor diameters
of any helicopter in a slow hover taxi or stationaryhover. In forward flight, departing or landing
helicopters produce a pair of strong, high −speed
trailing vortices similar to wing tip vortices of largerfixed wing aircraft. Pilots of small aircraft should use
caution when operating behind or crossing behind
landing and departing helicopters.
7−3−8. Pilot Responsibility
a.Government and industry groups are making
concerted efforts to minimize or eliminate thehazards of trailing vortices. However, the flight
disciplines necessary to ensure vortex avoidance
during VFR operations must be exercised by the pilot.
V ortex visualization and avoidance procedures
should be exercised by the pilot using the same degree
of concern as in collision avoidance.
b.Wake turbulence may be encountered by
aircraft in flight as well as when operating on the
airport movement area.
REFERENCE −
Pilot/Controller Glossary Term − Wake Turbulence.
c.Pilots are reminded that in operations conducted
behind all aircraft, acceptance of instructions from
ATC in the following situations is an acknowledg-
ment that the pilot will ensure safe takeoff and
landing intervals and accepts the responsibility for
providing wake turbulence separation.
1.Traffic information.
2.Instructions to follow an aircraft; and
3.The acceptance of a visual approach
clearance.
d.For operations conducted behind super or
heavy aircraft, ATC will specify the word “ super ” or
“heavy ” as appropriate, when this information is
known. Pilots of super or heavy aircraft should
always use the word “ super ” or “ heavy ” in radio
communications.
e.Super, heavy, and large jet aircraft operators
should use the following procedures during an
approach to landing. These procedures establish a
dependable baseline from which pilots of in −trail,
lighter aircraft may reasonably expect to make
effective flight path adjustments to avoid serious
wake vortex turbulence.
1.Pilots of aircraft that produce strong wake
vortices should make every attempt to fly on theestablished glidepath, not above it; or, if glidepath
guidance is not available, to fly as closely as possible
to a “3−1” glidepath, not above it.
EXAMPLE −
Fly 3,000 feet at 10 miles from touchdown, 1,500 feet at 5miles, 1,200 feet at 4 miles, and so on to touchdown.
AIM 10/12/17
7−3−7 Wake Turbulence2.Pilots of aircraft that produce strong wake
vortices should fly as closely as possible to the
approach course centerline or to the extended
centerline of the runway of intended landing as
appropriate to conditions.
f.Pilots operating lighter aircraft on visual
approaches in −trail to aircraft producing strong wake
vortices should use the following procedures to assist
in avoiding wake turbulence. These procedures apply
only to those aircraft that are on visual approaches.
1.Pilots of lighter aircraft should fly on or
above the glidepath. Glidepath reference may be
furnished by an ILS, by a visual approach slope
system, by other ground −based approach slope
guidance systems, or by other means. In the absence
of visible glidepath guidance, pilots may very nearly
duplicate a 3 −degree glideslope by adhering to the
“3 to 1” glidepath principle.
EXAMPLE −
Fly 3,000 feet at 10 miles from touchdown, 1,500 feet at
5 miles, 1,200 feet at 4 miles, and so on to touchdown.
2.If the pilot of the lighter following aircraft has
visual contact with the preceding heavier aircraft and
also with the runway, the pilot may further adjust forpossible wake vortex turbulence by the following
practices:
(a)Pick a point of landing no less than
1,000 feet from the arrival end of the runway.
(b)Establish a line −of−sight to that landing
point that is above and in front of the heavier
preceding aircraft.
(c)When possible, note the point of landing
of the heavier preceding aircraft and adjust point of
intended landing as necessary.
EXAMPLE −
A puff of smoke may appear at the 1,000 −foot markings of
the runway, showing that touchdown was that point;therefore, adjust point of intended landing to the1,500−foot markings.
(d)Maintain the line −of−sight to the point of
intended landing above and ahead of the heavier
preceding aircraft; maintain it to touchdown.
(e)Land beyond the point of landing of the
preceding heavier aircraft.
3.During visual approaches pilots may ask ATC
for updates on separation and groundspeed withrespect to heavier preceding aircraft, especially when
there is any question of safe separation from wake
turbulence.
7−3−9. Air Traffic Wake Turbulence
Separations
a.Because of the possible effects of wake
turbulence, controllers are required to apply no lessthan specified minimum separation to all IFR aircraft,
to all VFR aircraft receiving Class B or Class C
airspace services when operating behind super orheavy aircraft, and to small aircraft operating behind
a B757.
1.Separation is applied to aircraft operating
directly behind a super or heavy at the same altitude
or less than 1,000 feet below, and to small aircraft
operating directly behind a B757 at the same altitude
or less than 500 feet below:
(a) Heavy behind super − 6 miles.
(b) Large behind super − 7 miles.
(c) Small behind super − 8 miles.
(d) Heavy behind heavy −4 miles.
(e) Small/large behind heavy − 5 miles.
(f) Small behind B757 − 4 miles.
2.Also, separation, measured at the time the
preceding aircraft is over the landing threshold, is
provided to small aircraft:
(a) Small landing behind heavy − 6 miles.
(b) Small landing behind large, non −B757
−4 miles.
REFERENCE −
Pilot/Controller Glossary Term − Aircraft Classes.
3.Additionally, appropriate time or distance
intervals are provided to departing aircraft when the
departure will be from the same threshold, a parallel
runway separated by less than 2,500 feet with lessthan 500 feet threshold stagger, or on a crossing
runway and projected flight paths will cross:
(a)Three minutes or the appropriate radar
separation when takeoff will be behind a super
aircraft;
(b)Two minutes or the appropriate radar
separation when takeoff will be behind a heavyaircraft.
(c)Two minutes or the appropriate radar
separation when a small aircraft will takeoff behind
a B757.
AIM 10/12/17
7−3−8 Wake TurbulenceNOTE−
Controllers may not reduce or waive these intervals.
b.A 3−minute interval will be provided when a
small aircraft will takeoff:
1.From an intersection on the same runway
(same or opposite direction) behind a departing large
aircraft (except B757), or
2.In the opposite direction on the same runway
behind a large aircraft (except B757) takeoff or
low/missed approach.
NOTE−
This 3−minute interval may be waived upon specific pilot
request.
c.A 3−minute interval will be provided when a
small aircraft will takeoff:
1.From an intersection on the same runway
(same or opposite direction) behind a departingB757, or
2.In the opposite direction on the same runway
behind a B757 takeoff or low/missed approach.
NOTE−
This 3−minute interval may not be waived.d.A 4−minute interval will be provided for all
aircraft taking off behind a super aircraft, and a
3−minute interval will be provided for all aircraft
taking off behind a heavy aircraft when the operations
are as described in subparagraphs b1 and b2 above,and are conducted on either the same runway or
parallel runways separated by less than 2,500 feet.
Controllers may not reduce or waive this interval.
e.Pilots may request additional separation (i.e.,
2 minutes instead of 4 or 5 miles) for wake turbulence
avoidance. This request should be made as soon as
practical on ground control and at least before taxiing
onto the runway.
NOTE−
14 CFR Section 91.3(a) states: “The pilot −in−command of
an aircraft is directly responsible for and is the finalauthority as to the operation of that aircraft.”
f.Controllers may anticipate separation and need
not withhold a takeoff clearance for an aircraftdeparting behind a large, heavy, or super aircraft if
there is reasonable assurance the required separation
will exist when the departing aircraft starts takeoffroll.
AIM 10/12/17
7−4−1 Bird Hazards and Flight Over National Refuges, Parks, and ForestsSection 4. Bird Hazards and Flight Over National
Refuges, Parks, and Forests
7−4−1. Migratory Bird Activity
a.Bird strike risk increases because of bird
migration during the months of March through April,
and August through November.
b.The altitudes of migrating birds vary with winds
aloft, weather fronts, terrain elevations, cloudconditions, and other environmental variables. While
over 90 percent of the reported bird strikes occur at or
below 3,000 feet AGL, strikes at higher altitudes arecommon during migration. Ducks and geese are
frequently observed up to 7,000 feet AGL and pilots
are cautioned to minimize en route flying at loweraltitudes during migration.
c.Considered the greatest potential hazard to
aircraft because of their size, abundance, or habit offlying in dense flocks are gulls, waterfowl, vultures,
hawks, owls, egrets, blackbirds, and starlings.
Four major migratory flyways exist in the U.S. TheAtlantic flyway parallels the Atlantic Coast. The
Mississippi Flyway stretches from Canada through
the Great Lakes and follows the Mississippi River.The Central Flyway represents a broad area east of the
Rockies, stretching from Canada through Central
America. The Pacific Flyway follows the west coastand overflies major parts of Washington, Oregon, and
California. There are also numerous smaller flyways
which cross these major north-south migratoryroutes.
7−4−2. Reducing Bird Strike Risks
a.The most serious strikes are those involving
ingestion into an engine (turboprops and turbine jet
engines) or windshield strikes. These strikes can
result in emergency situations requiring promptaction by the pilot.
b.Engine ingestions may result in sudden loss of
power or engine failure. Review engine outprocedures, especially when operating from airports
with known bird hazards or when operating near high
bird concentrations.c.Windshield strikes have resulted in pilots
experiencing confusion, disorientation, loss of
communications, and aircraft control problems.
Pilots are encouraged to review their emergency
procedures before flying in these areas.
d.When encountering birds en route, climb to
avoid collision, because birds in flocks generally
distribute themselves downward, with lead birds
being at the highest altitude.
e.Avoid overflight of known areas of bird
concentration and flying at low altitudes during bird
migration. Charted wildlife refuges and other natural
areas contain unusually high local concentration ofbirds which may create a hazard to aircraft.
7−4−3. Reporting Bird Strikes
Pilots are urged to report any bird or other wildlife
strike using FAA Form 5200 −7, Bird/Other Wildlife
Strike Report (Appendix 1). Add itional forms are
available at any FSS; at any FAA Regional Office or
at https://www.faa.gov/airports/airport_safety/
wildlife/. The data derived from these reports are used
to develop standards to cope with this potential
hazard to aircraft and for documentation of necessary
habitat control on airports.
7−4−4. Reporting Bird and Other Wildlife
Activities
If you observe birds or other animals on or near the
runway, request airport management to disperse the
wildlife before taking off. Also contact the nearest
FAA ARTCC, FSS, or tower (including non −Federal
towers) regarding large flocks of birds and report the:
a.Geographic location.
b.Bird type (geese, ducks, gulls, etc.).
c.Approximate numbers.
d.Altitude.
e.Direction of bird flight path.
AIM 10/12/17
7−4−2 Bird Hazards and Flight Over National Refuges, Parks, and Forests7−4−5. Pilot Advisories on Bird and Other
Wildlife Hazards
Many airports advise pilots of other wildlife hazards
caused by large animals on the runway through the
Chart Supplement U.S. and the NOTAM system.Collisions of landing and departing aircraft and
animals on the runway are increasing and are not
limited to rural airports. These accidents have also
occurred at several major airports. Pilots should
exercise extreme caution when warned of thepresence of wildlife on and in the vicinity of airports.
If you observe deer or other large animals in close
proximity to movement areas, advise the FSS, tower,
or airport management.
7−4−6. Flights Over Charted U.S. Wildlife
Refuges, Parks, and Forest Service Areas
a.The landing of aircraft is prohibited on lands or
waters administered by the National Park Service,
U.S. Fish and W ildlife Service, or U.S. Forest Service
without authorization from the respective agency.
Exceptions include:
1.When forced to land due to an emergency
beyond the control of the operator;
2.At officially designated landing sites; or
3.An approved official business of the Federal
Government.
b.Pilots are requested to maintain a minimum
altitude of 2,000 feet above the surface of the
following: National Parks, Monuments, Seashores,Lakeshores, Recreation Areas and Scenic Riverways
administered by the National Park Service, National
Wildlife Refuges, Big Game Refuges, Game Ranges
and Wildlife Ranges administered by the U.S. Fish
and Wildlife Service, and Wilderness and Primitiveareas administered by the U.S. Forest Service.
NOTE−
F AA Advisory Circular AC 91 −36, Visual Flight
Rules (VFR) Flight Near Noise-Sensitive Areas, definesthe surface of a national park area (including parks,forests, primitive areas, wilderness areas, recreational
areas, national seashores, national monuments, national
lakeshores, and national wildlife refuge and range areas)as: the highest terrain within 2,000 feet laterally of theroute of flight, or the upper-most rim of a canyon or valley.
c.Federal statutes prohibit certain types of flight
activity and/or provide altitude restrictions overdesignated U.S. Wildlife Refuges, Parks, and Forest
Service Areas. These designated areas, for example:
Boundary Waters Canoe Wilderness Areas,Minnesota; Haleakala National Park, Hawaii;
Yosemite National Park, California; and Grand
Canyon National Park, Arizona, are charted onSectional Charts.
d.Federal regulations also prohibit airdrops by
parachute or other means of persons, cargo, or objects
from aircraft on lands administered by the threeagencies without authorization from the respective
agency. Exceptions include:
1.Emergencies involving the safety of human
life; or
2.Threat of serious property loss.
AIM 10/12/17
7−5−1 Potential Flight HazardsSection 5. Potential Flight Hazards
7−5−1. Accident Cause Factors
a.The 10 most frequent cause factors for general
aviation accidents that involve the pilot-in-command
are:
1. Inadequate preflight preparation and/or
planning.
2. Failure to obtain and/or maintain flying
speed.
3. Failure to maintain direction control.4. Improper level off.
5. Failure to see and avoid objects or
obstructions.
6. Mismanagement of fuel.
7. Improper inflight decisions or planning.8. Misjudgment of distance and speed.9. Selection of unsuitable terrain.
10. Improper operation of flight controls.
b.This list remains relatively stable and points out
the need for continued refresher training to establish
a higher level of flight proficiency for all pilots. A
part of the FAA’s continuing effort to promoteincreased aviation safety is the Aviation Safety
Program. For information on Aviation Safety
Program activities contact your nearest FlightStandards District Office.
c. Alertness. Be alert at all times, especially
when the weather is good. Most pilots pay attention
to business when they are operating in full IFR
weather conditions, but strangely, air collisions
almost invariably have occurred under ideal weather
conditions. Unlimited visibility appears to encourage
a sense of security which is not at all justified.
Considerable information of value may be obtained
by listening to advisories being issued in the terminalarea, even though controller workload may prevent a
pilot from obtaining individual service.
d. Giving Way. If you think another aircraft is too
close to you, give way instead of waiting for the other
pilot to respect the right-of-way to which you may beentitled. It is a lot safer to pursue the right-of-way
angle after you have completed your flight.
7−5−2. VFR in Congested Areas
A high percentage of near midair collisions occur
below 8,000 feet AGL and within 30 miles of anairport. When operating VFR in these highly
congested areas, whether you intend to land at an
airport within the area or are just flying through, it is
recommended that extra vigilance be maintained and
that you monitor an appropriate control frequency.
Normally the appropriate frequency is an approach
control frequency. By such monitoring action you can
“get the picture” of the traffic in your area. When the
approach controller has radar, radar traffic advisories
may be given to VFR pilots upon request.
REFERENCE −
AIM, Paragraph 4 −1−15 , Radar Traffic Information Service
7−5−3. Obstructions To Flight
a. General. Many structures exist that could
significantly affect the safety of your flight whenoperating below 500 feet AGL, and particularly
below 200 feet AGL. While 14 CFR Part 91.119
allows flight below 500 AGL when over sparsely
populated areas or open water, such operations are
very dangerous. At and below 200 feet AGL there are
numerous power lines, antenna towers, etc., that are
not marked and lighted as obstructions and; therefore,
may not be seen in time to avoid a collision. Noticesto Airmen (NOTAMs) are issued on those lighted
structures experiencing temporary light outages.
However, some time may pass before the FAA isnotified of these outages, and the NOTAM issued,
thus pilot vigilance is imperative.
b. Antenna Towers. Extreme caution should be
exercised when flying less than 2,000 feet AGLbecause of numerous skeletal structures, such as radio
and television antenna towers, that exceed 1,000 feet
AGL with some extending higher than 2,000 feetAGL. Most skeletal structures are supported by guy
wires which are very dif ficult to see in good weather
and can be invisible at dusk or during periods ofreduced visibility. These wires can extend about
1,500 feet horizontally from a structure; therefore, all
skeletal structures should be avoided horizontally by
AIM 10/12/17
7−5−2 Potential Flight Hazardsat least 2,000 feet. Additionally , new towers may not
be on your current chart because the information was
not received prior to the printing of the chart.
c. Overhead Wires. Overhead transmission and
utility lines often span approaches to runways,
natural flyways such as lakes, rivers, gorges, and
canyons, and cross other landmarks pilots frequently
follow such as highways, railroad tracks, etc. As with
antenna towers, these high voltage/power lines or the
supporting structures of these lines may not always be
readily visible and the wires may be virtually
impossible to see under certain conditions. In somelocations, the supporting structures of overhead
transmission lines are equipped with unique sequence
flashing white strobe light systems to indicate thatthere are wires between the structures. However,
many power lines do not require notice to the FAA
and, therefore, are not marked and/or lighted. Manyof those that do require notice do not exceed 200 feet
AGL or meet the Obstruction Standard of 14 CFR
Part 77 and, therefore, are not marked and/or lighted.
All pilots are cautioned to remain extremely vigilant
for these power lines or their supporting structures
when following natural flyways or during theapproach and landing phase. This is particularly
important for seaplane and/or float equipped aircraft
when landing on, or departing from, unfamiliar lakes
or rivers.
d. Other Objects/Structures. There are other
objects or structures that could adversely affect your
flight such as construction cranes near an airport,newly constructed buildings, new towers, etc. Many
of these structures do not meet charting requirements
or may not yet be charted because of the chartingcycle. Some structures do not require obstruction
marking and/or lighting and some may not be marked
and lighted even though the FAA recommended it.
7−5−4. Avoid Flight Beneath Unmanned
Balloons
a.The majority of unmanned free balloons
currently being operated have, extending below
them, either a suspension device to which the payload
or instrument package is attached, or a trailing wire
antenna, or both. In many instances these balloon
subsystems may be invisible to the pilot until theaircraft is close to the balloon, thereby creating a
potentially dangerous situation. Therefore, good
judgment on the part of the pilot dictates that aircraftshould remain well clear of all unmanned free
balloons and flight below them should be avoided at
all times.
b.Pilots are urged to report any unmanned free
balloons sighted to the nearest FAA ground facility
with which communication is established. Such
information will assist FAA AT C facilities to identify
and flight follow unmanned free balloons operating
in the airspace.
7−5−5. Unmanned Aircraft Systems
a.Unmanned Aircraft Systems (UAS), formerly
referred to as “Unmanned Aerial Vehicles” (UA Vs)or “drones,” are having an increasing operational
presence in the NAS. Once the exclusive domain of
the military, UAS are now being operated by various
entities. Although these aircraft are “unmanned,”
UAS are flown by a remotely located pilot and crew.Physical and performance characteristics of un-
manned aircraft (UA) vary greatly and unlike model
aircraft that typically operate lower than 400 feetAGL, UA may be found operating at virtually any
altitude and any speed. Sizes of UA can be as small
as several pounds to as large as a commercialtransport aircraft. UAS come in various categories
including airplane, rotorcraft, powered −lift (tilt−
rotor), and lighter −than−
air. Propulsion systems of
UAS include a broad range of alternatives from
piston powered and turbojet engines to battery and
solar−powered electric motors.
b.To ensure segregation of UAS operations from
other aircraft, the military typically conducts UAS
operations within restricted or other special use
airspace. However, UAS operations are now beingapproved in the NAS outside of special use airspace
through the use of FAA −issued Certificates of W aiver
or Authorization (COA) or through the issuance of aspecial airworthiness certificate. COA and special
airworthiness approvals authorize UAS flight
operations to be contained within specific geographic
boundaries and altitudes, usually require coordina-
tion with an ATC facility, and typically require the
issuance of a NOTAM describing the operation to be
conducted. UAS approvals also require observers to
provide “see−and−avoid” capability to the UAS crew
and to provide the necessary compliance with 14 CFRSection 91.113. For UAS operations approved at or
above FL180, UAS operate under the same
requirements as that of manned aircraft (i.e., flights
AIM 10/12/17
7−5−3 Potential Flight Hazardsare operated under instrument flight rules, are in
communication with ATC, and are appropriately
equipped).
c.UAS operations may be approved at either
controlled or uncontrolled airports and are typicallydisseminated by NOTAM. In all cases, approved
UAS operations must comply with all applicable
regulations and/or special provisions specified in the
COA or in the operating limitations of the special
airworthiness certificate. At uncontrolled airports,
UAS operations are advised to operate well clear ofall known manned aircraft operations. Pilots of
manned aircraft are advised to follow normal
operating procedures and are urged to monitor theCTAF for any potential UAS activity. At controlled
airports, local ATC procedures may be in place to
handle UAS operations and should not require anyspecial procedures from manned aircraft entering or
departing the traffic pattern or operating in the
vicinity of the airport.
d.In addition to approved UAS operations
described above, a recently approved agreement
between the FAA and the Department of Defenseauthorizes small UAS operations wholly contained
within Class G airspace, and in no instance, greater
than 1200 feet AGL over military owned or leased
property. These operations do not require any special
authorization as long as the UA remains within thelateral boundaries of the military installation as well
as other provisions including the issuance of a
NOTAM. Unlike special use airspace, these areasmay not be depicted on an aeronautical chart.
e.There are several factors a pilot should consider
regarding UAS activity in an effort to reducepotential flight hazards. Pilots are urged to exercise
increased vigilance when operating in the vicinity of
restricted or other special use airspace, militaryoperations areas, and any military installation. Areas
with a preponderance of UAS activity are typically
noted on sectional charts advising pilots of thisactivity. Since the size of a UA can be very small, they
may be difficult to see and track. If a UA is
encountered during flight, as with manned aircraft,never assume that the pilot or crew of the UAS can see
you, maintain increased vigilance with the UA and
always be prepared for evasive action if necessary.Always check NOTAMs for potential UAS activity
along the intended route of flight and exercise
increased vigilance in areas specified in the NOTAM.7−5−6. Mountain Flying
a.Your first experience of flying over mountain-
ous terrain (particularly if most of your flight time has
been over the flatlands of the midwest) could be anever-to-be-for gotten nightmare if proper planning is
not done and if you are not aware of the potential
hazards awaiting. Those familiar section lines are not
present in the mountains; those flat, level fields for
forced landings are practically nonexistent; abrupt
changes in wind direction and velocity occur; severe
updrafts and downdrafts are common, particularly
near or above abrupt changes of terrain such as cliffsor rugged areas; even the clouds look different and
can build up with startling rapidity. Mountain flying
need not be hazardous if you follow the recommenda-
tions below.
b. File a Flight Plan. Plan your route to avoid
topography which would prevent a safe forcedlanding. The route should be over populated areas and
well known mountain passes. Sufficient altitude
should be maintained to permit gliding to a safe
landing in the event of engine failure.
c.Don’t fly a light aircraft when the winds aloft, at
your proposed altitude, exceed 35 miles per hour.
Expect the winds to be of much greater velocity over
mountain passes than reported a few miles from them.
Approach mountain passes with as much altitude as
possible. Downdrafts of from 1,500 to 2,000 feet per
minute are not uncommon on the leeward side.
d.Don’t fly near or above abrupt changes in
terrain. Severe turbulence can be expected, especially
in high wind conditions.
e. Understand Mountain Obscuration. The
term Mountain Obscuration (MTOS) is used to
describe a visibility condition that is distinguishedfrom IFR because ceilings, by definition, aredescribed as “above ground level” (AGL). In
mountainous terrain clouds can form at altitudes
significantly higher than the weather reportingstation and at the same time nearby mountaintops
may be obscured by low visibility. In these areas the
ground level can also vary greatly over a small area.Beware if operating VFR −on−top. You could be
operating closer to the terrain than you think because
the tops of mountains are hidden in a cloud deckbelow. MTOS areas are identified daily on The
Aviation Weather Center located at:
http://www.aviationweather.gov .
AIM 10/12/17
7−5−4 Potential Flight Hazardsf.Some canyons run into a dead end. Don’t fly so
far up a canyon that you get trapped. ALWAYS BE
ABLE TO MAKE A 180 DEGREE TURN!
g.VFR flight operations may be conducted at
night in mountainous terrain with the application ofsound judgment and common sense. Proper pre-flight
planning, giving ample consideration to winds and
weather, knowledge of the terrain and pilotexperience in mountain flying are prerequisites for
safety of flight. Continuous visual contact with the
surface and obstructions is a major concern and flight
operations under an overcast or in the vicinity of
clouds should be approached with extreme caution.
h.When landing at a high altitude field, the same
indicated airspeed should be used as at low elevation
fields. Remember: that due to the less dense air at
altitude, this same indicated airspeed actually results
in higher true airspeed, a faster landing speed, and
more important, a longer landing distance. During
gusty wind conditions which often prevail at high
altitude fields, a power approach and power landingis recommended. Additionally, due to the faster
groundspeed, your takeoff distance will increase
considerably over that required at low altitudes.
i. Effects of Density Altitude. Performance
figures in the aircraft owner’s handbook for length of
takeoff run, horsepower, rate of climb, etc., are
generally based on standard atmosphere conditions
(59 degrees Fahrenheit (15 degrees Celsius), pressure29.92 inches of mercury) at sea level. However,
inexperienced pilots, as well as experienced pilots,
may run into trouble when they encounter analtogether different set of conditions. This is
particularly true in hot weather and at higher
elevations. Aircraft operations at altitudes above sealevel and at higher than standard temperatures are
commonplace in mountainous areas. Such operations
quite often result in a drastic reduction of aircraftperformance capabilities because of the changing air
density. Density altitude is a measure of air density.
It is not to be confused with pressure altitude, truealtitude or absolute altitude. It is not to be used as a
height reference, but as a determining criteria in the
performance capability of an aircraft. Air densitydecreases with altitude. As air density decreases,
density altitude increases. The further effects of high
temperature and high humidity are cumulative,
resulting in an increasing high density altitude
condition. High density altitude reduces all aircraftperformance parameters. To the pilot, this means that
the normal horsepower output is reduced, propeller
efficiency is reduced and a higher true airspeed isrequired to sustain the aircraft throughout its
operating parameters. It means an increase in runway
length requirements for takeoff and landings, anddecreased rate of climb. An average small airplane,
for example, requiring 1,000 feet for takeoff at sea
level under standard atmospheric conditions willrequire a takeoff run of approximately 2,000 feet at an
operational altitude of 5,000 feet.
NOTE−
A turbo-charged aircraft engine provides some slightadvantage in that it provides sea level horsepower up to a
specified altitude above sea level.
1. Density Altitude Advisories. At airports
with elevations of 2,000 feet and higher, control
towers and FSSs will broadcast the advisory “CheckDensity Altitude” when the temperature reaches a
predetermined level. These advisories will be
broadcast on appropriate tower frequencies or, where
available, ATIS. FSSs will broadcast these advisories
as a part of Local Airport Advisory, and on TWEB.
2.These advisories are provided by air traffic
facilities, as a reminder to pilots that high
temperatures and high field elevations will cause
significant changes in aircraft characteristics. Thepilot retains the responsibility to compute density
altitude, when appropriate, as a part of preflight
duties.
NOTE−
All FSSs will compute the current density altitude uponrequest.
j. Mountain Wave. Many pilots go all their lives
without understanding what a mountain wave is.
Quite a few have lost their lives because of this lackof understanding. One need not be a licensed
meteorologist to understand the mountain wave
phenomenon.
AIM 10/12/17
7−5−5 Potential Flight Hazards1.Mountain waves occur when air is being
blown over a mountain range or even the ridge of a
sharp bluff area. As the air hits the upwind side of the
range, it starts to climb, thus creating what is
generally a smooth updraft which turns into aturbulent downdraft as the air passes the crest of the
ridge. From this point, for many miles downwind,
there will be a series of downdrafts and updrafts.Satellite photos of the Rockies have shown mountain
waves extending as far as 700 miles downwind of the
range. Along the east coast area, such photos of theAppalachian chain have picked up the mountain
wave phenomenon over a hundred miles eastward.
All it takes to form a mountain wave is wind blowingacross the range at 15 knots or better at an intersection
angle of not less than 30 degrees.
2.Pilots from flatland areas should understand
a few things about mountain waves in order to stayout of trouble. When approaching a mountain range
from the upwind side (generally the west), there will
usually be a smooth updraft; therefore, it is not quiteas dangerous an area as the lee of the range. From the
leeward side, it is always a good idea to add an extra
thousand feet or so of altitude because downdrafts
can exceed the climb capability of the aircraft. Never
expect an updraft when approaching a mountainchain from the leeward. Always be prepared to cope
with a downdraft and turbulence.
3.When approaching a mountain ridge from the
downwind side, it is recommended that the ridge beapproached at approximately a 45 degree angle to the
horizontal direction of the ridge. This permits a safer
retreat from the ridge with less stress on the aircraftshould severe turbulence and downdraft be experi-
enced. If severe turbulence is encountered,
simultaneously reduce power and adjust pitch untilaircraft approaches maneuvering speed, then adjust
power and trim to maintain maneuvering speed and
fly away from the turbulent area.
7−5−7. Use of Runway Half −way Signs at
Unimproved Airports
When installed, runway half −way signs provide the
pilot with a reference point to judge takeoff
acceleration trends. Assuming that the runway length
is appropriate for takeoff (considering runwaycondition and slope, elevation, aircraft weight, wind,
and temperature), typical takeoff acceleration should
allow the airplane to reach 70 percent of lift −off
airspeed by the midpoint of the runway. The “rule of
thumb” is that should airplane acceleration not allowthe airspeed to reach this value by the midpoint, the
takeoff should be aborted, as it may not be possible to
liftoff in the remaining runway.
Several points are important when considering using
this “rule of thumb”:
a.Airspeed indicators in small airplanes are not
required to be evaluated at speeds below stalling, and
may not be usable at 70 percent of liftoff airspeed.
b.This “rule of thumb” is based on a uniform
surface condition. Puddles, soft spots, areas of talland/or wet grass, loose gravel, etc., may impede
acceleration or even cause deceleration. Even if the
airplane achieves 70 percent of liftoff airspeed by themidpoint, the condition of the remainder of the runway
may not allow further acceleration. The entire length
of the runway should be inspected prior to takeoff toensure a usable surface.
c.This “rule of thumb” applies only to runway
required for actual liftoff. In the event that obstacles
affect the takeoff climb path, appropriate distance
must be available after liftoff to accelerate to best angleof climb speed and to clear the obstacles. This will, in
effect, require the airplane to accelerate to a higher
speed by midpoint, particularly if the obstacles areclose to the end of the runway. In addition, this
technique does not take into account the effects of
upslope or tailwinds on takeoff performance. Thesefactors will also require greater acceleration than
normal and, under some circumstances, prevent
takeoff entirely.
d.Use of this “rule of thumb” does not alleviate the
pilot’s responsibility to comply with applicableFederal Aviation Regulations, the limitations and
performance data provided in the FAA approved
Airplane Flight Manual (AFM), or, in the absence ofan FAA approved AFM, other data provided by the
aircraft manufacturer.
In addition to their use during takeoff, runway
half−way signs offer the pilot increased awareness of
his or her position along the runway during landing
operations.
AIM 10/12/17
7−5−6 Potential Flight HazardsNOTE−
No F AA standard exists for the appearance of the runwayhalf−way sign. FIG 7−5−1 shows a graphical depiction of
a typical runway half −way sign.
7−5−8. Seaplane Safety
a.Acquiring a seaplane class rating af fords access
to many areas not available to landplane pilots.
Adding a seaplane class rating to your pilot certificate
can be relatively uncomplicated and inexpensive.
However, more effort is required to become a safe,
efficient, competent “bush” pilot. The natural hazards
of the backwoods have given way to modern
man-made hazards. Except for the far north, the
available bodies of water are no longer the exclusive
domain of the airman. Seaplane pilots must be
vigilant for hazards such as electric power lines,
power, sail and rowboats, rafts, mooring lines, waterskiers, swimmers, etc.
FIG 7−5−1
Typical Runway Half −way Sign
b.Seaplane pilots must have a thorough under-
standing of the right-of-way rules as they apply to
aircraft versus other vessels. Seaplane pilots areexpected to know and adhere to both the U.S. Coast
Guard’s (USCG) Navigation Rules, International −In-
land, and 14 CFR Section 91.115, Right −of−Way
Rules; Water Operations. The navigation rules of the
road are a set of collision avoidance rules as they
apply to aircraft on the water. A seaplane isconsidered a vessel when on the water for the
purposes of these collision avoidance rules. In
general, a seaplane on the water must keep well clearof all vessels and avoid impeding their navigation.
The CFR requires, in part, that aircraft operating on
the water “. . . shall, insofar as possible, keep clear of
all vessels and avoid impeding their navigation, and
shall give way to any vessel or other aircraft that isgiven the right −of−way . . . .” This means that a
seaplane should avoid boats and commercial
shipping when on the water. If on a collision course,the seaplane should slow, stop, or maneuver to the
right, away from the bow of the oncoming vessel.
Also, while on the surface with an engine running, an
aircraft must give way to all nonpowered vessels.
Since a seaplane in the water may not be as
maneuverable as one in the air, the aircraft on thewater has right-of-way over one in the air, and one
taking off has right-of-way over one landing. A
seaplane is exempt from the USCG safety equipment
requirements, including the requirements for Person-
al Flotation Devices (PFD). Requiring seaplanes on
the water to comply with USCG equipmentrequirements in addition to the FAA equipment
requirements would be an unnecessary burden on
seaplane owners and operators.
c.Unless they are under Federal jurisdiction,
navigable bodies of water are under the jurisdiction
of the state, or in a few cases, privately owned. Unless
they are specifically restricted, aircraft have as much
right to operate on these bodies of water as othervessels. To avoid problems, check with Federal or
local officials in advance of operating on unfamiliar
waters. In addition to the agencies listed inTBL 7−5−1, the nearest Flight Standards District
Office can usually of fer some practical suggestions as
well as regulatory information. If you land on arestricted body of water because of an inflight
emergency, or in ignorance of the restrictions you
have violated, report as quickly as practical to thenearest local official having jurisdiction and explain
your situation.
d.When operating a seaplane over or into remote
areas, appropriate attention should be given to
survival gear. Minimum kits are recommended for
summer and winter, and are required by law for flight
into sparsely settled areas of Canada and Alaska.
Alaska State Department of Transportation and
Canadian Ministry of T ransport officials can provide
specific information on survival gear requirements.
The kit should be assembled in one container and be
easily reachable and preferably floatable.
AIM 10/12/17
7−5−7 Potential Flight HazardsTBL 7−5−1
Jurisdictions Controlling Navigable Bodies of Water
Authority to Consult For Use of a Body of Water
Location Authority Contact
Wilderness Area U.S. Department
of Agriculture,
Forest ServiceLocal forest ranger
National Forest USDA Forest
ServiceLocal forest ranger
National Park U.S. Departmentof the Interior,
National ParkServiceLocal park ranger
Indian Reservation USDI, Bureau of
Indian AffairsLocal Bureauoffice
State Park State governmentor state forestry or
park serviceLocal state
aviation office for
furtherinformation
Canadian National
and Provincial
ParksSupervised and
restricted on an
individual basisfrom province toprovince and bydifferentdepartments of the
Canadian
government;consult CanadianFlight InformationManual and/or
Water Aerodrome
SupplementPark
Superintendent in
an emergency
e.The FAA recommends that each seaplane owner
or operator provide flotation gear for occupants any
time a seaplane operates on or near water. 14 CFRSection 91.205(b)(12) requires approved flotation
gear for aircraft operated for hire over water and
beyond power-off gliding distance from shore.FAA-approved gear differs from that required for
navigable waterways under USCG rules. FAA-ap-
proved life vests are inflatable designs as comparedto the USCG’s noninflatable PFD’s that may consist
of solid, bulky material. Such USCG PFDs are
impractical for seaplanes and other aircraft becausethey may block passage through the relatively narrow
exits available to pilots and passengers. Life vests
approved under Technical Standard Order (TSO)TSO−C13E contain fully inflatable compartments.
The wearer inflates the compartments (AFTER
exiting the aircraft) primarily by independent CO2cartridges, with an oral inflation tube as a backup. The
flotation gear also contains a water-activated,
self-illuminating signal light. The fact that pilots andpassengers can easily don and wear inflatable life
vests (when not inflated) provides maximum
effectiveness and allows for unrestricted movement.
It is imperative that passengers are briefed on the
location and proper use of available PFDs prior toleaving the dock.
f.The FAA recommends that seaplane owners and
operators obtain Advisory Circular (AC) 91 −69,
Seaplane Safety for 14 CFR Part 91 Operations, free
from the U.S. Department of Transportation,
Subsequent Distribution Office, SVC −121.23, Ard-
more East Business Center, 3341 Q 75
th Avenue,
Landover, MD 20785; fax: (301) 386 −5394. The
USCG Navigation Rules International −Inland
(COMDTINSTM 16672.2B) is available for a fee
from the Government Printing Office by facsimile
request to (202) 512 −2250, and can be ordered using
Mastercard or Visa.
7−5−9. Flight Operations in Volcanic Ash
a.Severe volcanic eruptions which send ash and
sulphur dioxide (SO 2) gas into the upper atmosphere
occur somewhere around the world several times
each year. Flying into a volcanic ash cloud can be
exceedingly dangerous. A B747 −200 lost all four
engines after such an encounter and a B747 −400 had
the same nearly catastrophic experience. Piston −
powered aircraft are less likely to lose power butsevere damage is almost certain to ensue after an
encounter with a volcanic ash cloud which is only a
few hours old.
b.Most important is to avoid any encounter with
volcanic ash. The ash plume may not be visible,
especially in instrument conditions or at night; andeven if visible, it is difficult to distinguish visually
between an ash cloud and an ordinary weather cloud.
V olcanic ash clouds are not displayed on airborne orATC radar. The pilot must rely on reports from air
traffic controllers and other pilots to determine the
location of the ash cloud and use that information toremain well clear of the area. Additionally, the
presence of a sulphur-like odor throughout the cabin
may indicate the presence of SO
2 emitted by volcanic
activity, but may or may not indicate the presence of
volcanic ash. Every attempt should be made to remain
on the upwind side of the volcano.
c.It is recommended that pilots encountering an
ash cloud should immediately reduce thrust to idle
(altitude permitting), and reverse course in order to
AIM 10/12/17
7−5−8 Potential Flight Hazardsescape from the cloud. Ash clouds may extend for
hundreds of miles and pilots should not attempt to fly
through or climb out of the cloud. In addition, the
following procedures are recommended:
1.Disengage the autothrottle if engaged. This
will prevent the autothrottle from increasing enginethrust;
2.Turn on continuous ignition;
3.Turn on all accessory airbleeds including all
air conditioning packs, nacelles, and wing anti-ice.This will provide an additional engine stall margin by
reducing engine pressure.
d.The following has been reported by flightcrews
who have experienced encounters with volcanic dustclouds:
1.Smoke or dust appearing in the cockpit.
2.An acrid odor similar to electrical smoke.
3.Multiple engine malfunctions, such as
compressor stalls, increasing EGT, torching from
tailpipe, and flameouts.
4.At night, St. Elmo’s fire or other static
discharges accompanied by a bright orange glow inthe engine inlets.
5.A fire warning in the forward cargo area.
e.It may become necessary to shut down and then
restart engines to prevent exceeding EGT limits.V olcanic ash may block the pitot system and result in
unreliable airspeed indications.
f.If you see a volcanic eruption and have not been
previously notified of it, you may have been the first
person to observe it. In this case, immediately contact
ATC and alert them to the existence of the eruption.If possible, use the V olcanic Activity Reporting form
(VAR) depicted in Appendix 2 of this manual.
Items 1 through 8 of the V AR should be transmittedimmediately. The information requested in
items 9 through 16 should be passed after landing. If
a V AR form is not immediately available, relayenough information to identify the position and
nature of the volcanic activity. Do not become
unnecessarily alarmed if there is merely steam or very
low-level eruptions of ash.
g.When landing at airports where volcanic ash has
been deposited on the runway, be aware that even a
thin layer of dry ash can be detrimental to brakingaction. Wet ash on the runway may also reduce
effectiveness of braking. It is recommended that
reverse thrust be limited to minimum practical to
reduce the possibility of reduced visibility and engine
ingestion of airborne ash.
h.When departing from airports where volcanic
ash has been deposited, it is recommended that pilots
avoid operating in visible airborne ash. Allow ash to
settle before initiating takeoff roll. It is alsorecommended that flap extension be delayed until
initiating the before takeoff checklist and that a
rolling takeoff be executed to avoid blowing ash back
into the air.
7−5−10. Emergency Airborne Inspection of
Other Aircraft
a.Providing airborne assistance to another aircraft
may involve flying in very close proximity to that
aircraft. Most pilots receive little, if any, formal
training or instruction in this type of flying activity.Close proximity flying without sufficient time to plan
(i.e., in an emergency situation), coupled with the
stress involved in a perceived emergency can behazardous.
b.The pilot in the best position to assess the
situation should take the responsibility of coordinat-
ing the airborne intercept and inspection, and takeinto account the unique flight characteristics and
differences of the category(s) of aircraft involved.
c.Some of the safety considerations are:
1.Area, direction and speed of the intercept;
Aerodynamic effects (i.e., rotorcraft down-
wash);
3.Minimum safe separation distances;
4.Communications requirements, lost commu-
nications procedures, coordination with ATC;
5.Suitability of diverting the distressed aircraft
to the nearest safe airport; and
6.Emergency actions to terminate the intercept.
d.Close proximity, inflight inspection of another
aircraft is uniquely hazardous. The pilot −in−
command of the aircraft experiencing the
problem/emergency must not relinquish control ofthe situation and/or jeopardize the safety of their
aircraft. The maneuver must be accomplished with
minimum risk to both aircraft.
AIM 10/12/17
7−5−9 Potential Flight Hazards7−5−11. Precipitation Static
a.Precipitation static is caused by aircraft in flight
coming in contact with uncharged particles. These
particles can be rain, snow, fog, sleet, hail, volcanicash, dust; any solid or liquid particles. When the
aircraft strikes these neutral particles the positive
element of the particle is reflected away from the
aircraft and the negative particle adheres to the skin
of the aircraft. In a very short period of time asubstantial negative charge will develop on the skin
of the aircraft. If the aircraft is not equipped with
static dischargers, or has an ineffective staticdischarger system, when a suf ficient negative voltage
level is reached, the aircraft may go into
“CORONA.” That is, it will discharge the staticelectricity from the extremities of the aircraft, such as
the wing tips, horizontal stabilizer, vertical stabilizer,
antenna, propeller tips, etc. This discharge of staticelectricity is what you will hear in your headphones
and is what we call P −static.
b.A review of pilot reports often shows different
symptoms with each problem that is encountered.
The following list of problems is a summary of manypilot reports from many different aircraft. Each
problem was caused by P −static:
1.Complete loss of VHF communications.
2.Erroneous magnetic compass readings
(30 percent in error).
3.High pitched squeal on audio.
4.Motor boat sound on audio.
5.Loss of all avionics in clouds.
6.VLF navigation system inoperative most of
the time.
7.Erratic instrument readouts.
8.Weak transmissions and poor receptivity of
radios.
9.“St. Elmo’s Fire” on windshield.
c.Each of these symptoms is caused by one
general problem on the airframe. This problem is the
inability of the accumulated charge to flow easily to
the wing tips and tail of the airframe, and properly
discharge to the airstream.d.Static dischargers work on the principal of
creating a relatively easy path for discharging
negative char ges that develop on the aircraft by using
a discharger with fine metal points, carbon coated
rods, or carbon wicks rather than wait until a largecharge is developed and discharged off the trailing
edges of the aircraft that will interfere with avionics
equipment. This process offers approximately50 decibels (dB) static noise reduction which is
adequate in most cases to be below the threshold of
noise that would cause interference in avionicsequipment.
e.It is important to remember that precipitation
static p roblems can only be corrected with the proper
number of quality static dischargers, properly
installed on a properly bonded aircraft. P −static is
indeed a problem in the all weather operation of theaircraft, but there are effective ways to combat it. All
possible methods of reducing the effects of P −static
should be considered so as to provide the bestpossible performance in the flight environment.
f.A wide variety of discharger designs is available
on the commercial market. The inclusion ofwell−designed dischargers may be expected to
improve airframe noise in P −static conditions by as
much as 50 dB. Essentially, the discharger provides
a path by which accumulated charge may leave the
airframe quietly. This is generally accomplished byproviding a group of tiny corona points to permit
onset of corona −current flow at a low aircraft
potential. Additionally, aerodynamic design of
dischargers to permit corona to occur at the lowest
possible atmospheric pressure also lowers the corona
threshold. In addition to permitting a low −potential
discharge, the discharger will minimize the radiation
of radio frequency (RF) energy which accompanies
the corona discharge, in order to minimize effects ofRF components at communications and navigation
frequencies on avionics performance. These effects
are reduced through resistive attachment of thecorona point(s) to the airframe, preserving direct
current connection but attenuating the higher −fre-
quency components of the discharge.
g.Each manufacturer of static dischargers offers
information concerning appropriate discharger loca-
tion on specific airframes. Such locations emphasizethe trailing outboard surfaces of wings and horizontal
tail surfaces, plus the tip of the vertical stabilizer,
where charge tends to accumulate on the airframe.
AIM 10/12/17
7−5−10 Potential Flight HazardsSufficient dischargers must be provided to allow for
current−carrying capacity which will maintain
airframe potential below the corona threshold of the
trailing edges.
h.In order to achieve full performance of avionic
equipment, the static discharge system will require
periodic maintenance. A pilot knowledgeable of
P−static causes and effects is an important element in
assuring optimum performance by early recognitionof these types of problems.
7−5−12. Light Amplification by Stimulated
Emission of Radiation (Laser) Operationsand Reporting Illumination of Aircraft
a.Lasers have many applications. Of concern to
users of the National Airspace System are those laser
events that may affect pilots, e.g., outdoor laser light
shows or demonstrations for entertainment andadvertisements at special events and theme parks.
Generally, the beams from these events appear as
bright blue−green in color; however, they may be red,
yellow, or white. However, some laser systems
produce light which is invisible to the human eye.
b.FAA regulations prohibit the disruption of
aviation activity by any person on the ground or in the
air. The FAA and the Food and Drug Administration
(the Federal agency that has the responsibility to
enforce compliance with Federal requirements forlaser systems and laser light show products) are
working together to ensure that operators of these
devices do not pose a hazard to aircraft operators.
c.Pilots should be aware that illumination from
these laser operations are able to create temporary
vision impairment miles from the actual location. In
addition, these operations can produce permanent eye
damage. Pilots should make themselves aware of
where these activities are being conducted and avoid
these areas if possible.
d.Recent and increasing incidents of unautho-
rized illumination of aircraft by lasers, as well as the
proliferation and increasing sophistication of laser
devices available to the general public, dictates thatthe FAA, in coordination with other government
agencies, take action to safeguard flights from these
unauthorized illuminations.e.Pilots should report laser illumination activity to
the controlling Air Traffic Control facilities, Federal
Contract T owers or Flight Service Stations as soon as
possible after the event. The following information
should be included:
1.UTC Date and Time of Event.
2.Call Sign or Aircraft Registration Number.
3.Type Aircraft.
4.Nearest Major City.
5.Altitude.
6.Location of Event (Latitude/Longitude and/
or Fixed Radial Distance (FRD)).
7.Brief Description of the Event and any other
Pertinent Information.
f.Pilots are also encouraged to complete the
Laser Beam Exposure Questionnaire locatedon the FAA Laser Safety Initiative website at
http://www.faa.gov/about/initiatives/lasers/
and submit electronically per the directions on thequestionnaire, as soon as possible after landing.
g.When a laser event is reported to an air traffic
facility, a general caution warning will be broad-
casted on all appropriate frequencies every
five minutes for 20 minutes and broadcasted on theATIS for one hour following the report.
PHRASEOLOGY −
UNAUTHORIZED LASER ILLUMINATION EVENT,(UTC time), (location), (altitude), (color), (direction).
EXAMPLE −
“Unauthorized laser illumination event, at 0100z, 8 milefinal runway 18R at 3,000 feet, green laser from thesouthwest.”
REFERENCE −
F AA Order JO 7110.65, Paragraph 10 −2−14, Unauthorized Laser
Illumination of Aircraft
F AA Order JO 7210.3, Paragraph 2−1−27, Reporting Unauthorized
Laser Illumination of Aircraft
h.When these activities become known to the
FAA, Notices to Airmen (NOTAMs) are issued to
inform the aviation community of the events. Pilotsshould consult NOTAMs or the Special Notices
section of the Chart Supplement U.S. for information
regarding these activities.
AIM 10/12/17
7−5−11 Potential Flight Hazards7−5−13. Flying in Flat Light and White Out
Conditions
a. Flat Light. Flat light is an optical illusion, also
known as “ sector or partial white out .” It is not as
severe as “white out” but the condition causes pilots
to lose their depth −of−field and contrast in vision.
Flat light conditions are usually accompanied by
overcast skies inhibiting any visual clues. Such
conditions can occur anywhere in the world,primarily in snow covered areas but can occur in dust,
sand, mud flats, or on glassy water. Flat light can
completely obscure features of the terrain, creating an
inability to distinguish distances and closure rates.
As a result of this reflected light, it can give pilots the
illusion that they are ascending or descending whenthey may actually be flying level. However, with
good judgment and proper training and planning, it is
possible to safely operate an aircraft in flat light
conditions.
b. White Out. As defined in meteorological
terms, white out occurs when a person becomesengulfed in a uniformly white glow. The glow is a
result of being surrounded by blowing snow, dust,
sand, mud or water. There are no shadows, no horizon
or clouds and all depth −of−field and orientation are
lost. A white out situation is severe in that there are
no visual references. Flying is not recommended inany white out situation. Flat light conditions can lead
to a white out environment quite rapidly, and both
atmospheric conditions are insidious; they sneak up
on you as your visual references slowly begin to
disappear. White out has been the cause of severalaviation accidents.
c. Self Induced White Out. This effect typically
occurs when a helicopter takes off or lands on a
snow−covered area. The rotor down wash picks up
particles and re −circulates them through the rotor
down wash. The effect can vary in intensity
depending upon the amount of light on the surface.This can happen on the sunniest, brightest day with
good contrast everywhere. However, when it
happens, there can be a complete loss of visual clues.
If the pilot has not prepared for this immediate loss of
visibility, the results can be disastrous. Good
planning does not prevent one from encountering flat
light or white out conditions.d. Never
take off in a white out situation.
1.Realize that in flat light conditions it may be
possible to depart but not to return to that site. During
takeoff, make sure you have a reference point. Do not
lose sight of it until you have a departure referencepoint in view. Be prepared to return to the takeoff
reference if the departure reference does not come
into view.
2.Flat light is common to snow skiers. One way
to compensate for the lack of visual contrast and
depth−of−field loss is by wearing amber tinted lenses
(also known as blue blockers). Special note ofcaution: Eyewear is not
ideal for every pilot. Take
into consideration personal factors − age, light
sensitivity, and ambient lighting conditions.
3.So what should a pilot do when all visual
references are lost?
(a)Trust the cockpit instruments.
(b)Execute a 180 degree turnaround and start
looking for outside references.
(c)Above all − fly the aircraft.
e. Landing in Low Light Conditions. When
landing in a low light condition − use extreme
caution. Look for intermediate reference points, in
addition to checkpoints along each leg of the route for
course confirmation and timing. The lower the
ambient light becomes, the more reference points a
pilot should use.
f. Airport Landings.
1.Look for features around the airport or
approach path that can be used in determining depth
perception. Buildings, towers, vehicles or other
aircraft serve well for this measurement. Use
something that will provide you with a sense of height
above the ground, in addition to orienting you to therunway.
2.Be cautious of snowdrifts and snow banks −
anything that can distinguish the edge of the runway.
Look for subtle changes in snow texture or shading to
identify ridges or changes in snow depth.
g. Off−Airport Landings.
1.In the event of an off −airport landing, pilots
have used a number of different visual cues to gain
reference. Use whatever you must to create the
contrast you need. Natural references seem to work
best (trees, rocks, snow ribs, etc.)
AIM 10/12/17
7−5−12 Potential Flight Hazards(a)Over flight.
(b)Use of markers.
(c)Weighted flags.
(d)Smoke bombs.
(e)Any colored rags.
(f)Dye markers.
(g)Kool−aid.
(h)Trees or tree branches.
2.It is difficult to determine the depth of snow
in areas that are level. Dropping items from the
aircraft to use as reference points should be used as a
visual aid only and not as a primary landing reference.
Unless your marker is biodegradable, be sure to
retrieve it after landing. Never put yourself in a
position where no visual references exist.
3.Abort landing if blowing snow obscures your
reference. Make your decisions early. Don’t assume
you can pick up a lost reference point when you get
closer.
4.Exercise extreme caution when flying from
sunlight into shade. Physical awareness may tell you
that you are flying straight but you may actually be in
a spiral dive with centrifugal force pressing againstyou. Having no visual references enhances this
illusion. Just because you have a good visual
reference does not mean that it’s safe to continue.There may be snow −covered terrain not visible in the
direction that you are traveling. Getting caught in a no
visual reference situation can be fatal.
h. Flying Around a Lake.
1.When flying along lakeshores, use them as a
reference point. Even if you can see the other side,
realize that your depth perception may be poor. It is
easy to fly into the surface. If you must cross the lake,
check the altimeter frequently and maintain a safe
altitude while you still have a good reference. Don’t
descend below that altitude.
2.The same rules apply to seemingly flat areas
of snow. If you don’t have good references, avoid
going there.
i. Other Traffic. Be on the look out for other
traffic in the area. Other aircraft may be using your
same reference point. Chances are greater ofcolliding with someone traveling in the same
direction as you, than someone flying in the opposite
direction.
j. Ceilings. Low ceilings have caught many pilots
off guard. Clouds do not always form parallel to the
surface, or at the same altitude. Pilots may try to
compensate for this by flying with a slight bank andthus creating a descending turn.
k. Glaciers. Be conscious of your altitude when
flying over glaciers. The glaciers may be rising faster
than you are climbing.
7−5−14. Operations in Ground Icing
Conditions
a.The presence of aircraft airframe icing during
takeoff, typically caused by improper or no deicing of
the aircraft being accomplished prior to flight has
contributed to many recent accidents in turbine
aircraft. The General Aviation Joint SteeringCommittee (GAJSC) is the primary vehicle for
government −industry cooperation, communication,
and coordination on GA accident mitigation. TheTurbine Aircraft Operations Subgroup (TAOS)
works to mitigate accidents in turbine accident
aviation. While there is sufficient information and
guidance currently available regarding the effects of
icing on aircraft and methods for deicing, the TAOS
has developed a list of recommended actions tofurther assist pilots and operators in this area.
While the efforts of the TAOS specifically focus on
turbine aircraft, it is recognized that their recommen-
dations are applicable to and can be adapted for the
pilot of a small, piston powered aircraft too.
b.The following recommendations are offered:
1.Ensure that your aircraft’s lift −generating
surfaces are COMPLETELY free of contamination
before flight through a tactile (hands on) check of the
critical surfaces when feasible. Even when otherwise
permitted, operators should avoid smooth or polished
frost on lift −generating surfaces as an acceptable
preflight condition.
2.Review and refresh your cold weather
standard operating procedures.
3.Review and be familiar with the Airplane
Flight Manual (AFM) limitations and procedures
necessary to deal with icing conditions prior to flight,
as well as in flight.
AIM 10/12/17
7−5−13 Potential Flight Hazards4.Protect your aircraft while on the ground, if
possible, from sleet and freezing rain by taking
advantage of aircraft hangars.
5.Take full advantage of the opportunities
available at air ports for deicing. Do not refuse deicing
services simply because of cost.
6.Always consider canceling or delaying a
flight if weather conditions do not support a safe
operation.
c.If you haven’t already developed a set of
Standard Operating Procedures for cold weatheroperations, they should include:
1.Procedures based on information that is
applicable to the aircraft operated, such as AFM
limitations and procedures;
2.Concise and easy to understand guidance that
outlines best operational practices;
3.A systematic procedure for recognizing,
evaluating and addressing the associated icing risk,and offer clear guidance to mitigate this risk;
4.An aid (such as a checklist or reference cards)
that is readily available during normal day −to−day
aircraft operations.
d.There are several sources for guidance relating
to airframe icing, including:
http://aircrafticing.grc.nasa.gov/index.html
2.http://www.ibac.org/is −bao/isbao.htm
3.http://www.natasafety1st.org/bus_deice.htm
4.Advisory Circular (AC) 91 −74, Pilot Guide,
Flight in Icing Conditions.
5.AC 135−17, Pilot Guide Small Aircraft
Ground Deicing.
6.AC 135−9, FAR Part 135 Icing Limitations.
7.AC 120−60, Ground Deicing and Anti −icing
Program.
8.AC 135−16, Ground Deicing and Anti −icing
Training and Checking.
The FAA Approved Deicing Program Updates is
published annually as a Flight Standards Information
Bulletin for Air Transportation and contains detailed
information on deicing and anti −icing procedures and
holdover times. It may be accessed at the following
website by selecting the current year’s informationbulletins:
http://www.faa.gov/library/manuals/examiners_inspe
ctors/8400/fsat
7−5−15. Avoid Flight in the Vicinity of
Exhaust Plumes (Smoke Stacks andCooling Towers)
a. Flight Hazards Exist Around Exhaust
Plumes. Exhaust plumes are defined as visible or
invisible emissions from power plants, industrial
production facilities, or other industrial systems that
release large amounts of vertically directed unstablegases (effluent). High temperature exhaust plumes
can cause significant air disturbances such as
turbulence and vertical shear. Other identifiedpotential hazards include, but are not necessarily
limited to: reduced visibility, oxygen depletion,
engine particulate contamination, exposure togaseous oxides, and/or icing. Results of encountering
a plume may include airframe damage, aircraft upset,
and/or engine damage/failure. These hazards are
most critical during low altitude flight in calm and
cold air, especially in and around approach anddeparture corridors or airport traffic areas.
Whether plumes are visible or invisible, the totalextent of their turbulent affect is difficult to predict.
Some studies do predict t hat the significant turbulent
effects of an exhaust plume can extend to heights ofover 1,000 feet above the height of the top of the stack
or cooling tower. Any effects will be more
pronounced in calm stable air where the plume is very
hot and the surrounding area is still and cold.
Fortunately, studies also predict that any amount of
crosswind will help to dissipate the effects. However,
the size of the tower or stack is not a good indicator
of the predicted effect the plume may produce. The
major effects are related to the heat or size of theplume effluent, the ambient air temperature, and the
wind speed affecting the plume. Smaller aircraft can
expect to feel an effect at a higher altitude thanheavier aircraft.
b. When able, a pilot should steer clear of
exhaust plumes by flying on the upwind side ofsmokestacks or cooling towers. When a plume is
visible via smoke or a condensation cloud, remain
clear and realize a plume may have both visible andinvisible characteristics. Exhaust stacks without
visible plumes may still be in full operation, and
airspace in the vicinity should be treated with caution.
AIM 10/12/17
7−5−14 Potential Flight HazardsAs with mountain wave turbulence or clear air
turbulence, an invisible plume may be encountered
unexpectedly. Cooling towers, power plant stacks,
exhaust fans, and other similar structures are depicted
in FIG 7−5−2.
Pilots are encouraged to exercise caution when flying
in the vicinity of exhaust plumes. Pilots are also
encouraged to reference the Chart Supplement U.S.
where amplifying notes may caution pilots andidentify the location of structure(s) emitting exhaust
plumes.The best available information on this phenomenon
must come from pilots via the PIREP reporting
procedures. All pilots encountering hazardous
plume conditions are urgently requested to report
time, location, and intensity ( light, moderate, severe,
or extreme) of the element to the FAA facility with
which they are maintaining radio contact. If time and
conditions permit, elements should be reportedaccording to the standards for other PIREPs and
position reports (AIM Paragraph 7 −1−23, PIREPS
Relating to Turbulence).
FIG 7−5−2
Plumes
AIM 10/12/17
7−6−1 Safety, Accident, and Hazard ReportsSection 6. Safety, Accident, and Hazard Reports
7−6−1. Aviation Safety Reporting Program
a.The FAA has established a voluntary Aviation
Safety Reporting Program designed to stimulate the
free and unrestricted flow of information concerningdeficiencies and discrepancies in the aviation system.
This is a positive program intended to ensure the
safest possible system by identifying and correctingunsafe conditions before they lead to accidents. The
primary objective of the program is to obtain
information to evaluate and enhance the safety and
efficiency of the present system.
b.This cooperative safety reporting program
invites pilots, controllers, flight attendants, mainte-
nance personnel and other users of the airspace
system, or any other person, to file written reports of
actual or potential discrepancies and deficiencies
involving the safety of aviation operations. The
operations covered by the program include departure,
en route, approach, and landing operations and
procedures, air traffic control procedures andequipment, crew and air traffic control communica-
tions, aircraft cabin operations, aircraft movement on
the airport, near midair collisions, aircraft mainte-nance and record keeping and airport conditions or
services.
c.The report should give the date, time, location,
persons and aircraft involved (if applicable), nature
of the event, and all pertinent details.
d.To ensure receipt of this information, the
program provides for the waiver of certain
disciplinary actions against persons, including pilots
and air traffic controllers, who file timely written
reports concerning potentially unsafe incidents. To be
considered timely, reports must be delivered or
postmarked within 10 days of the incident unless that
period is extended for good cause. Reports should be
submitted on NASA ARC Forms 277, which are
available free of charge, postage prepaid, at FAA
Flight Standards District Offices and Flight ServiceStations, and from NASA, ASRS, PO Box 189,
Moffet Field, CA 94035.
e.The FAA utilizes the National Aeronautics and
Space Administration (NASA) to act as an
independent third party to receive and analyze reports
submitted under the program. This program isdescribed in AC 00 −46, Aviation Safety Reporting
Program.
7−6−2. Aircraft Accident and Incident
Reporting
a. Occurrences Requiring Notification. The
operator of an aircraft must immediately, and by the
most expeditious means available, notify the nearest
National Transportation Safety Board (NTSB) FieldOffice when:
1.An aircraft accident or any of the following
listed incidents occur:
(a)Flight control system malfunction or
failure.
(b)Inability of any required flight crew
member to perform their normal flight duties as a
result of injury or illness.
(c)Failure of structural components of a
turbine engine excluding compressor and turbineblades and vanes.
(d)Inflight fire.
(e)Aircraft collide in flight.
(f)Damage to property, other than the
aircraft, estimated to exceed $25,000 for repair(including materials and labor) or fair market value in
the event of total loss, whichever is less.
(g)For large multi-engine aircraft (more than
12,500 pounds maximum certificated takeoff
weight):
(1)
Inflight failure of electrical systems
which requires the sustained use of an emergency bus
powered by a back-up source such as a battery,
auxiliary power unit, or air -driven generator to retain
flight control or essential instruments;
(2)Inflight failure of hydraulic systems
that results in sustained reliance on the sole remaining
hydraulic or mechanical system for movement of
flight control surfaces;
(3)Sustained loss of the power or thrust
produced by two or more engines; and
(4)An evacuation of aircraft in which an
emergency egress system is utilized.
AIM 10/12/17
7−6−2 Safety, Accident, and Hazard Reports2.An aircraft is overdue and is believed to have
been involved in an accident.
b. Manner of Notification.
1.The most expeditious method of notification
to the NTSB by the operator will be determined by the
circumstances existing at that time. The NTSB hasadvised that any of the following would be
considered examples of the type of notification that
would be acceptable:
(a)Direct telephone notification.
(b)Telegraphic notification.
(c)Notification to the FAA who would in turn
notify the NTSB by direct communication; i.e., dis-
patch or telephone.
c. Items to be Included in Notification. The
notification required above must contain thefollowing information, if available:
1.Type, nationality, and registration marks of
the aircraft.
2.Name of owner and operator of the aircraft.
3.Name of the pilot-in-command.
4.Date and time of the accident, or incident.
5.Last point of departure, and point of intended
landing of the aircraft.
6.Position of the aircraft with reference to some
easily defined geographical point.
7.Number of persons aboard, number killed,
and number seriously injured.
8.Nature of the accident, or incident, the
weather, and the extent of damage to the aircraft so far
as is known; and
9.A description of any explosives, radioactive
materials, or other dangerous articles carried.
d. Follow −up Reports.
1.The operator must file a report on NTSB
Form 6120.1 or 6120.2, available from NTSB FieldOffices or from the NTSB, Washington, DC, 20594:
(a)Within 10 days after an accident;
(b)When, after 7 days, an overdue aircraft is
still missing;(c)A report on an incident for which
notification is required as described in subpara-
graph a(1) must be filed only as requested by an
authorized representative of the NTSB.
2.Each crewmember, if physically able at the
time the report is submitted, must attach a statement
setting forth the facts, conditions, and circumstances
relating to the accident or incident as they appeared.If the crewmember is incapacitated, a statement must
be submitted as soon as physically possible.
e. Where to File the Reports.
1.The operator of an aircraft must file with the
NTSB Field Office nearest the accident or incidentany report required by this section.
2.The NTSB Field Of fices are listed under U.S.
Government in the telephone directories in the
following cities: Anchorage, AK; Atlanta, GA;
Chicago, IL; Denver, CO; Fort Worth, TX;Los Angeles, CA; Miami, FL; Parsippany, NJ;
Seattle, WA.
7−6−3. Near Midair Collision Reporting
a. Purpose and Data Uses. The primary purpose
of the Near Midair Collision (NMAC) Reporting
Program is to provide information for use inenhancing the safety and efficiency of the National
Airspace System. Data obtained from NMAC reports
are used by the FAA to improve the quality of FAAservices to users and to develop programs, policies,
and procedures aimed at the reduction of NMAC
occurrences. All NMAC reports are thoroughly
investigated by Flight Standards Facilities in
coordination with Air Traffic Facilities. Data from
these investigations are transmitted to FAA Head-quarters in W ashington, DC, where they are compiled
and analyzed, and where safety programs and
recommendations are developed.
b. Definition. A near midair collision is defined
as an incident associated with the operation of anaircraft in which a possibility of collision occurs as a
result of proximity of less than 500 feet to another
aircraft, or a report is received from a pilot or a flight
crew member stating that a collision hazard existed
between two or more aircraft.
c. Reporting Responsibility. It is the responsi-
bility of the pilot and/or flight crew to determine
whether a near midair collision did actually occur
and, if so, to initiate a NMAC report. Be specific, as
AIM 10/12/17
7−6−3 Safety, Accident, and Hazard ReportsATC will not interpret a casual remark to mean that
a NMAC is being reported. The pilot should state “I
wish to report a near midair collision.”
d. Where to File Reports. Pilots and/or flight
crew members involved in NMAC occurrences are
urged to report each incident immediately:
1.By radio or telephone to the nearest FAA ATC
facility or FSS.
2.In writing, in lieu of the above, to the nearest
Flight Standards District Office (FSDO).
e. Items to be Reported.
1.Date and time (UTC) of incident.
2.Location of incident and altitude.
3.Identification and type of reporting aircraft,
aircrew destination, name and home base of pilot.
4.Identification and type of other aircraft,
aircrew destination, name and home base of pilot.
5.Type of flight plans; station altimeter setting
used.
6.Detailed weather conditions at altitude or
flight level.
7.Approximate courses of both aircraft:
indicate if one or both aircraft were climbing or
descending.
8.Reported separation in distance at first
sighting, proximity at closest point horizontally andvertically, and length of time in sight prior to evasive
action.
9.Degree of evasive action taken, if any (from
both aircraft, if possible).
10.Injuries, if any.
f. Investigation. The FSDO in whose area the
incident occurred is responsible for the investigation
and reporting of NMACs.
g.Existing radar, communication, and weather
data will be examined in the conduct of theinvestigation. When possible, all cockpit crew
members will be interviewed regarding factors
involving the NMAC incident. Air traffic controllers
will be interviewed in cases where one or more of theinvolved aircraft was provided ATC service. Both
flight and ATC procedures will be evaluated. When
the investigation reveals a violation of an FAA
regulation, enforcement action will be pursued.
7−6−4. Unidentified Flying Object (UFO)
Reports
a.Persons wanting to report UFO/unexplained
phenomena activity should contact a UFO/unex-
plained phenomena reporting data collection center,such as the National UFO Reporting Center, etc.
b.If concern is expressed that life or property
might be endangered, report the activity to the local
law enforcement department.
7−6−5. Safety Alerts For Operators (SAFO)
and Information For Operators (InFO)
a.SAFOs contain important safety information
that is often time-critical. A SAFO may contain
information and/or recommended (non-regulatory)
action to be taken by the respective operators orparties identified in the SAFO. The audience for
SAFOs varies with each subject and may include: Air
carrier certificate holders, air operator certificateholders, general aviation operators, directors of
safety, directors of operations, directors of mainten-
ance, fractional ownership program managers,training center managers, accountable managers at
repair stations, and other parties as applicable.
b.InFOs are similar to SAFOs, but contain
valuable information for operators that should helpthem meet administrative requirements or certain
regulatory requirements with relatively low urgency
or impact in safety.
c.
The SAFO and InFO system provides a means
to rapidly distribute this information to operators and
can be found at the following website:
http://www.faa.gov/other_visit/aviation_industry/
airline_operators/airline_safety/safo and
http://www.faa.gov/other_visit/aviation_industry/
airline_operators/airline_safety/info
or search keyword FAA SAFO or FAA INFO. Free
electronic subscription is available on the “ALL
SAFOs” or “ALL InFOs” page of the website.
AIM 10/12/17
8−1−1 Fitness for FlightChapter 8. Medical Facts for Pilots
Section 1. Fitness for Flight
8−1−1. Fitness For Flight
a. Medical Certification.
1.All pilots except those flying gliders and free
air balloons must possess valid medical certificates inorder to exercise the privileges of their airman
certificates. The periodic medical examinations
required for medical certification are conducted bydesignated Aviation Medical Examiners, who are
physicians with a special interest in aviation safety
and training in aviation medicine.
2.The standards for medical certification are
contained in 14 CFR Part 67. Pilots who have a
history of certain medical conditions described in
these standards are mandatorily disqualified from
flying. These medical conditions include apersonality disorder manifested by overt acts, a
psychosis, alcoholism, drug dependence, epilepsy,
an unexplained disturbance of consciousness,myocardial infarction, angina pectoris and diabetes
requiring medication for its control. Other medical
conditions may be temporarily disqualifying, such as
acute infections, anemia, and peptic ulcer. Pilots who
do not meet medical standards may still be qualified
under special issuance provisions or the exemptionprocess. This may require that either additional
medical information be provided or practical flight
tests be conducted.
3.Student pilots should visit an Aviation
Medical Examiner as soon as possible in their flighttraining in order to avoid unnecessary training
expenses should they not meet the medical standards.
For the same reason, the student pilot who plans toenter commercial aviation should apply for the
highest class of medical certificate that might be
necessary in the pilot’s career.
CAUTION −
The CFRs prohibit a pilot who possesses a currentmedical certificate from performing crewmember dutieswhile the pilot has a known medical condition or increase
of a known medical condition that would make the pilot
unable to meet the standards for the medical certificate.b. Illness.
1.Even a minor illness suffered in day-to-day
living can seriously degrade performance of many
piloting tasks vital to safe flight. Illness can produce
fever and distracting symptoms that can impairjudgment, memory, alertness, and the ability to make
calculations. Although symptoms from an illness
may be under adequate control with a medication, themedication itself may decrease pilot performance.
2.The safest rule is not to fly while suffering
from any illness. If this rule is considered too
stringent for a particular illness, the pilot should
contact an Aviation Medical Examiner for advice.
c. Medication.
1.Pilot performance can be seriously degraded
by both prescribed and over-th e-counter medications,
as well as by the medical conditions for which theyare taken. Many medications, such as tranquilizers,
sedatives, strong pain relievers, and cough-suppres-
sant preparations, have primary effects that mayimpair judgment, memory, alertness, coordination,
vision, and the ability to make calculations. Others,
such as antihistamines, blood pres sure drugs, muscle
relaxants, and agents to control diarrhea and motion
sickness, have side effects that may impair the same
critical functions. Any medication that depresses thenervous system, such as a sedative, tranquilizer or
antihistamine, can make a pilot much more
susceptible to hypoxia.
2.The CFRs prohibit pilots from performing
crewmember duties while using any medication thataffects the faculties in any way contrary to safety. The
safest rule is not to fly as a crewmember while taking
any medication, unless approved to do so by the FAA.
d. Alcohol.
1.Extensive research has provided a number of
facts about the hazards of alcohol consumption and
flying. As little as one ounce of liquor, one bottle ofbeer or four ounces of wine can impair flying skills,
with the alcohol consumed in these drinks being
detectable in the breath and blood for at least 3 hours.
Even after the body completely destroys a moderate
amount of alcohol, a pilot can still be severely
AIM 10/12/17
8−1−2 Fitness for Flightimpaired for many hours by hangover. There is
simply no way of increasing the destruction of
alcohol or alleviating a hangover. Alcohol also
renders a pilot much more susceptible to disorienta-
tion and hypoxia.
2.A consistently high alcohol related fatal
aircraft accident rate serves to emphasize that alcohol
and flying are a potentially lethal combination. The
CFRs prohibit pilots from performing crewmemberduties within 8 hours after drinking any alcoholic
beverage or while under the influence of alcohol.
However, due to the slow destruction of alcohol, apilot may still be under influence 8 hours after
drinking a moderate amount of alcohol. Therefore, an
excellent rule is to allow at least 12 to 24 hoursbetween “bottle and throttle,” depending on the
amount of alcoholic beverage consumed.
e. Fatigue.
1.Fatigue continues to be one of the most
treacherous hazards to flight safety, as it may not be
apparent to a pilot until serious errors are made.
Fatigue is best described as either acute (short-term)or chronic (long-term).
2.A normal occurrence of everyday living,
acute fatigue is the tiredness felt after long periods of
physical and mental strain, including strenuous
muscular effort, immobility , heavy mental workload,
strong emotional pressure, monotony, and lack ofsleep. Consequently, coordination and alertness, so
vital to safe pilot performance, can be reduced. Acute
fatigue is prevented by adequate rest and sleep, aswell as by regular exercise and proper nutrition.
3.Chronic fatigue occurs when there is not
enough time for full recovery between episodes ofacute fatigue. Performance continues to fall off, and
judgment becomes impaired so that unwarranted
risks may be taken. Recovery from chronic fatiguerequires a prolonged period of rest.
4.OBSTRUCTIVE SLEEP APNEA (OSA).
OSA is now recognized as an important preventable
factor identified in transportation accidents. OSAinterrupts the normal restorative sleep necessary for
normal functioning and is associated with chronic
illnesses such as hypertension, heart attack, stroke,obesity, and diabetes. Symptoms include snoring,
excessive daytime sleepiness, intermittent prolonged
breathing pauses while sleeping, memory impair-ment and lack of concentration. There are many
available treatments which can reverse the day time
symptoms and reduce the chance of an accident. OSA
can be easily treated. Most treatments are acceptable
for medical certification upon demonstrating effect-ive treatment. If you have any symptoms described
above, or neck size over 17 inches in men or 16 inches
in women, or a body mass index greater than 30 youshould be evaluated for sleep apnea by a sleep
medicine specialist.
(https://www.cdc.gov/he althyweight/assessing/
bmi/adult_bmi/english_bmi_calculator/bmi_calc
ulator.html ) With treatment you can avoid or delay
the onset of these chronic illnesses and prolong aquality life.
f. Stress.
1.Stress from the pressures of everyday living
can impair pilot performance, often in very subtle
ways. Difficulties, particularly at work, can occupy
thought processes enough to markedly decreasealertness. Distraction can so interfere with judgment
that unwarranted risks are taken, such as flying into
deteriorating weather conditions to keep on schedule.
Stress and fatigue (see above) can be an extremely
hazardous combination.
2.Most pilots do not leave stress “on the
ground.” Therefore, when more than usual difficul-
ties are being experienced, a pilot should considerdelaying flight until these difficulties are satisfac-
torily resolved.
g. Emotion.
Certain emotionally upsetting events, including a
serious argument, death of a family member,
separation or divorce, loss of job, and financialcatastrophe, can render a pilot unable to fly an aircraft
safely. The emotions of anger, depression, and
anxiety from such events not only decrease alertness
but also may lead to taking risks that border on
self-destruction. Any pilot who experiences an
emotionally upsetting event should not fly untilsatisfactorily recovered from it.
h. Personal Checklist. Aircraft accident statis-
tics show that pilots should be conducting preflight
checklists on themselves as well as their aircraft for
pilot impairment contributes to many more accidents
than failures of aircraft systems. A personal checklist,
which includes all of the categories of pilot
impairment as discussed in this section, that can be
AIM 10/12/17
8−1−3 Fitness for Flighteasily committed to memory is being distributed by
the FAA in the form of a wallet-sized card.
i. PERSONAL CHECKLIST. I’m physically
and mentally safe to fly; not being impaired by:
Illness
Medication
Stress
Alcohol
Fatigue
Emotion
8−1−2. Effects of Altitude
a. Hypoxia.
1.Hypoxia is a state of oxygen deficiency in the
body sufficient to impair functions of the brain and
other organs. Hypoxia from exposure to altitude is
due only to the reduced barometric pressures
encountered at altitude, for the concentration of
oxygen in the atmosphere remains about 21 percentfrom the ground out to space.
2.Although a deterioration in night vision
occurs at a cabin pressure altitude as low as
5,000 feet, other significant effects of altitudehypoxia usually do not occur in the normal healthy
pilot below 12,000 feet. From 12,000 to 15,000 feet
of altitude, judgment, memory, alertness, coordina-tion and ability to make calculations are impaired,
and headache, drowsiness, dizziness and either a
sense of well-being (euphoria) or belligerence occur.
The effects appear following increasingly shorter
periods of exposure to increasing altitude. In fact,
pilot performance can seriously deteriorate within15 minutes at 15,000 feet.
3.At cabin pressure altitudes above 15,000 feet,
the periphery of the visual field grays out to a point
where only central vision remains (tunnel vision). Ablue coloration (cyanosis) of the fingernails and lips
develops. The ability to take corrective and protective
action is lost in 20 to 30 minutes at 18,000 feet and5 to 12 minutes at 20,000 feet, followed soon
thereafter by unconsciousness.
4.The altitude at which significant effects of
hypoxia occur can be lowered by a number of factors.
Carbon monoxide inhaled in smoking or fromexhaust fumes, lowered hemoglobin (anemia), and
certain medications can reduce the oxygen-carrying
capacity of the blood to the degree that the amount of
oxygen provided to body tissues will already be
equivalent to the oxygen provided to the tissues when
exposed to a cabin pressure altitude of several
thousand feet. Small amounts of alcohol and low
doses of certain drugs, such as antihistamines,tranquilizers, sedatives and analgesics can, through
their depressant action, render the brain much more
susceptible to hypoxia. Extreme heat and cold, fever,
and anxiety increase the body’s demand for oxygen,
and hence its susceptibility to hypoxia.
5.The effects of hypoxia are usually quite
difficult to recognize, especially when they occur
gradually. Since symptoms of hypoxia do not vary in
an individual, the ability to recognize hypoxia can be
greatly improved by experiencing and witnessing the
effects of hypoxia during an altitude chamber“flight.” The FAA provides this opportunity through
aviation physiology training, which is conducted at
the FAA Civil Aeromedical Institute and at manymilitary facilities across the U.S. To attend the
Physiological Training Program at the Civil
Aeromedical I nstitute, Mike Monroney Aeronautical
Center, Oklahoma City, OK, contact by telephone
(405) 954 −6212, or by writing Aerospace Medical
Education Division, AAM −400, CAMI, Mike
Monroney Aeronautical Center, P.O. Box 25082,
Oklahoma City, OK 73125.
NOTE−
To attend the physiological training program at one of themilitary installations having the training capability, anapplication form and a fee must be submitted. Fullparticulars about location, fees, scheduling procedures,
course content, individual requirements, etc., are con-
tained in the Physiological Training Application, FormNumber AC 3150 −7, which is obtained by contacting the
accident pr evention specialist or the office forms manager
in the nearest F AA office.
6.Hypoxia is prevented by heeding factors that
reduce to lerance to altitude, by enriching the inspired
air with oxygen from an appropriate oxygen system,and by maintaining a comfortable, safe cabin
pressure altitude. For optimum protection, pilots are
encouraged to use supplemental oxygen above
AIM 10/12/17
8−1−4 Fitness for Flight10,000 feet during the day, and above 5,000 feet at
night. The CFRs require that at the minimum, flight
crew be provided with and use supplemental oxygen
after 30 minutes of exposure to cabin pressure
altitudes between 12,500 and 14,000 feet andimmediately on exposure to cabin pressure altitudes
above 14,000 feet. Every occupant of the aircraft
must be provided with supplemental oxygen at cabin
pressure altitudes above 15,000 feet.
b. Ear Block.
1.As the aircraft cabin pressure decreases
during ascent, the expanding air in the middle ear
pushes the eustachian tube open, and by escaping
down it to the nasal passages, equalizes in pressurewith the cabin pressure. But during descent, the pilot
must periodically open the eustachian tube to
equalize pressure. This can be accomplished by
swallowing, yawning, tensing muscles in the throat,
or if these do not work, by a combination of closingthe mouth, pinching the nose closed, and attempting
to blow through the nostrils (Valsalva maneuver).
2.Either an upper respiratory infection, such as
a cold or sore throat, or a nasal allergic condition can
produce enough congestion around the eustachian
tube to make equalization dif ficult. Consequently, the
difference in pressure between the middle ear and
aircraft cabin can build up to a level that will hold the
eustachian tube closed, making equalization dif ficult
if not impossible. The problem is commonly referred
to as an “ear block.”
3.An ear block produces severe ear pain and
loss of hearing that can last from several hours to
several days. Rupture of the ear drum can occur in
flight or after landing. Fluid can accumulate in the
middle ear and become infected.
4.An ear block is prevented by not flying with
an upper respiratory infection or nasal allergic
condition. Adequate protection is usually not
provided by decongestant sprays or drops to reducecongestion around the eustachian tubes. Oral
decongestants have side ef fects that can significantly
impair pilot performance.
5.If an ear block does not clear shortly after
landing, a physician should be consulted.
c. Sinus Block.1.During ascent and descent, air pressure in the
sinuses equalizes with the aircraft cabin pressure
through small openings that connect the sinuses to the
nasal passages. Either an upper respiratory infection,
such as a cold or sinusitis, or a nasal aller gic condition
can produce enough congestion around an opening to
slow equalization, and as the difference in pressure
between the sinus and cabin mounts, eventually plug
the opening. This “sinus block” occurs most
frequently during descent.
2.A sinus block can occur in the frontal sinuses,
located above each eyebrow, or in the maxillarysinuses, located in each upper cheek. It will usually
produce excruciating pain over the sinus area. A
maxillary sinus block can also make the upper teethache. Bloody mucus may discharge from the nasal
passages.
3.A sinus block is prevented by not flying with
an upper respiratory infection or nasal allergic
condition. Adequate protection is usually not
provided by decongestant sprays or drops to reducecongestion around the sinus openings. Oral decon-
gestants have side effects that can impair pilot
performance.
4.If a sinus block does not clear shortly after
landing, a physician should be consulted.
d. Decompression Sickness After Scuba
Diving.
1.A pilot or passenger who intends to fly after
scuba diving should allow the body sufficient time to
rid itself of excess nitrogen absorbed during diving.
If not, decompression sickness due to evolved gas can
occur during exposure to low altitude and create a
serious inflight emergency.
2.The recommended waiting time before going
to flight altitudes of up to 8,000 feet is at least
12 hours after diving which has not required
controlled ascent (nondecompression stop diving),and at least 24 hours after diving which has required
controlled ascent (decompression stop diving). The
waiting time before going to flight altitudes above8,000 feet should be at least 24 hours after any
SCUBA dive. These recommended altitudes are
actual flight altitudes above mean sea level (AMSL)and not pressurized cabin altitudes. This takes into
consideration the risk of decompression of the
aircraft during flight.
AIM 10/12/17
8−1−5 Fitness for Flight8−1−3. Hyperventilation in Flight
a.Hyperventilation, or an abnormal increase in
the volume of air breathed in and out of the lungs, canoccur subconsciously when a stressful situation is
encountered in flight. As hyperventilation “blows
off” excessive carbon dioxide from the body, a pilotcan experience symptoms of lightheadedness,
suffocation, drowsiness, tingling in the extremities,
and coolness and react to them with even greater
hyperventilation. Incapacitation can eventually result
from incoordination, disorientation, and painful
muscle spasms. Finally, unconsciousness can occur.
b.The symptoms of hyperventilation subside
within a few minutes after the rate and depth ofbreathing are consciously brought back under
control. The buildup of carbon dioxide in the body
can be hastened by controlled breathing in and out ofa paper bag held over the nose and mouth.
c.Early symptoms of hyperventilation and
hypoxia are similar. Moreover, hyperventilation and
hypoxia can occur at the same time. Therefore, if apilot is using an oxygen system when symptoms are
experienced, the oxy gen regulator should immediate-
ly be set to deliver 100 percent oxygen, and then thesystem checked to assure that it has been functioning
effectively before giving attention to rate and depth of
breathing.
8−1−4. Carbon Monoxide Poisoning in
Flight
a.Carbon monoxide is a colorless, odorless, and
tasteless gas contained in exhaust fumes. When
breathed even in minute quantities over a period of
time, it can significantly reduce the ability of theblood to carry oxygen. Consequently, effects of
hypoxia occur.
b.Most heaters in light aircraft work by air
flowing over the manifold. Use of these heaters while
exhaust fumes are escaping through manifold cracks
and seals is responsible every year for several
nonfatal and fatal aircraft accidents from carbon
monoxide poisoning.
c.A pilot who detects the odor of exhaust or
experiences symptoms of headache, drowsiness, ordizziness while using the heater should suspect
carbon monoxide poisoning, and immediately shut
off the heater and open air vents. If symptoms aresevere or continue after landing, medical treatment
should be sought.
8−1−5. Illusions in Flight
a. Introduction. Many different illusions can be
experienced in flight. Some can lead to spatial
disorientation. Others can lead to landing errors.Illusions rank a mong the most common factors cited
as contributing to fatal aircraft accidents.
b. Illusions Leading to Spatial Disorientation.
1.Various complex motions and forces and
certain visual scenes encountered in flight can create
illusions of motion and position. Spatial disorienta-
tion from these illusions can be prevented only by
visual refer ence to reliable, fixed points on the ground
or to flight instruments.
2. The leans. An abrupt correction of a banked
attitude, which has been entered too slowly to
stimulate the motion sensing system in the inner ear,
can create the illusion of banking in the opposite
direction. The disoriented pilot will roll the aircraft
back into its original dangerous attitude, or if levelflight is maintained, will feel compelled to lean in the
perceived vertical plane until this illusion subsides.
(a) Coriolis illusion. An abrupt head move-
ment in a prolonged constant-rate turn that has ceased
stimulating the motion sensing system can create the
illusion of rotation or movement in an entirely
different axis. The disoriented pilot will maneuver the
aircraft into a dangerous attitude in an attempt to stop
rotation. This most overwhelming of all illusions in
flight may be prevented by not making sudden,extreme head movements, particularly while making
prolonged constant-rate turns under IFR conditions.
(b) Graveyard spin. A proper recovery
from a spin that has ceased stimulating the motionsensing system can create the illusion of spinning in
the opposite direction. The disoriented pilot will
return the aircraft to its original spin.
(c) Graveyard spiral. An observed loss of
altitude during a coordinated constant-rate turn that
has ceased stimulating the motion sensing system can
create the illusion of being in a descent with the wings
level. The disoriented pilot will pull back on the
controls, tightening the spiral and increasing the loss
of altitude.
(d) Somatogravic illusion. A rapid accel-
eration during takeoff can create the illusion of being
AIM 10/12/17
8−1−6 Fitness for Flightin a nose up attitude. The disoriented pilot will push
the aircraft into a nose low, or dive attitude. A rapid
deceleration by a quick reduction of the throttles can
have the opposite effect, with the disoriented pilot
pulling the aircraft into a nose up, or stall attitude.
(e) Inversion illusion. An abrupt change
from climb to straight and level flight can create the
illusion of tumbling backwards. The disoriented pilot
will push the aircraft abruptly into a nose low attitude,
possibly intensifying this illusion.
(f) Elevator illusion. An abrupt upward
vertical acceleration, usually by an updraft, can create
the illusion of being in a climb. The disoriented pilot
will push the aircraft into a nose low attitude. Anabrupt downward vertical acceleration, usually by a
downdraft, has the opposite effect, with the
disoriented pilot pulling the aircraft into a nose upattitude.
(g) False horizon. Sloping cloud forma-
tions, an obscured horizon, a dark scene spread withground lights and stars, and certain geometric
patterns of ground light can create illusions of not
being aligned correctly with the actual horizon. Thedisoriented pilot will place the aircraft in a dangerous
attitude.
(h) Autokinesis. In the dark, a static light
will appear to move about when stared at for many
seconds. The disoriented pilot will lose control of the
aircraft in attempting to align it with the light.
3. Illusions Leading to Landing Errors.
(a)Various surface features and atmospheric
conditions encountered in landing can create illusions
of incorrect height above and distance from the
runway threshold. Landing errors from these
illusions can be prevented by anticipating themduring approaches, aerial visual inspection of
unfamiliar airports before landing, using electronic
glide slope or V ASI systems when available, andmaintaining optimum proficiency in landing
procedures.
(b) Runway width illusion. A narrower-
than-usual runway can creat e the illusion that the
aircraft is at a higher altitude than it actually is. The
pilot who does not recognize this illusion will fly alower approach, with the risk of striking objects along
the approach path or landing short. A wider-than-
usual runway can have the opposite effect, with therisk of leveling out high and landing hard or
overshooting the runway.
(c) Runway and terrain slopes illusion. An
upsloping runway, upsloping terrain, or both, can
create the illusion that the aircraft is at a higheraltitude than it actually is. The pilot who does not
recognize this illusion will fly a lower approach. A
downsloping runway, downsloping approach terrain,
or both, can have the opposite effect.
(d) Featureless terrain illusion. An
absence of ground features, as when landing over
water, darkened areas, and terrain made featureless
by snow, can create the illusion that the aircraft is ata higher altitude than it actually is. The pilot who does
not recognize this illusion will fly a lower approach.
(e) Atmospheric illusions. Rain on the
windscreen can create the illusion of greater height,
and atmospheric haze the illusion of being at a greater
distance from the runway. The pilot who does not
recognize these illusions will fly a lower approach.
Penetration of fog can create the illusion of pitchingup. The pilot who does not recognize this illusion will
steepen the approach, often quite abruptly.
(f) Ground lighting illusions. Lights along
a straight path, such as a road, and even lights on
moving trains can be mistaken for runway and
approach lights. Bright runway and approach lighting
systems, especially where few lights illuminate the
surrounding terrain, may create the illusion of less
distance to the runway. The pilot who does not
recognize this illusion will fly a higher approach.
Conversely, the pilot overflying terrain w hich has few
lights to provide height cues may make a lower than
normal approach.
8−1−
6. Vision in Flight
a. Introduction. Of the body senses, vision is the
most important for safe flight. Major factors that
determine how effectively vision can be used are the
level of illumination and the technique of scanningthe sky for other aircraft.
b. Vision Under Dim and Bright Illumination.
1.Under conditions of dim illumination, small
print and colors on aeronautical charts and aircraft
instruments become unreadable unless adequatecockpit lighting is available. Moreover, another
aircraft must be much closer to be seen unless its
navigation lights are on.
AIM 10/12/17
8−1−7 Fitness for Flight2.In darkness, vision becomes more sensitive to
light, a process called dark adaptation. Although
exposure to total darkness for at least 30 minutes is
required for complete dark adaptation, a pilot can
achieve a moderate degree of dark adaptation within20 minutes under dim red cockpit lighting. Since red
light severely distorts colors, especially on aeronauti-
cal charts, and can cause serious dif ficulty in focusing
the eyes on objects inside the aircraft, its use is
advisable only where optimum outside night vision
capability is necessary. Even so, white cockpitlighting must be available when needed for map and
instrument reading, especially under IFR conditions.
Dark adaptation is impaired by exposure to cabinpressure altitudes above 5,000 feet, carbon monoxide
inhaled in smoking and from exhaust fumes,
deficiency of V itamin A in the diet, and by prolonged
exposure to bright sunlight. Since any degree of dark
adaptation is lost within a few seconds of viewing a
bright light, a pilot should close one eye when usinga light to preserve some degree of night vision.
3.Excessive illumination, especially from light
reflected off the canopy, surfaces inside the aircraft,
clouds, water, snow, and desert terrain, can produce
glare, with uncomfortable squinting, watering of the
eyes, and even temporary blindness. Sunglasses forprotection from glare should absorb at least
85 percent of visible light (15 percent transmittance)
and all colors equally (neutral transmittance), withnegligible image distortion from refractive and
prismatic errors.
c. Scanning for Other Aircraft.
1.Scanning the sky for other aircraft is a key
factor in collision avoidance. It should be usedcontinuously by the pilot and copilot (or right seat
passenger) to cover all areas of the sky visible from
the cockpit. Although pilots must meet specific visualacuity requirements, the ability to read an eye chart
does not ensure that one will be able to ef ficiently spot
other aircraft. Pilots must develop an effectivescanning technique which maximizes one’s visual
capabilities. The probability of spotting a potential
collision threat obviously increases with the time
spent looking outside the cockpit. Thus, one must use
timesharing techniques to efficiently scan thesurrounding airspace while monitoring instruments
as well.2.While the eyes can observe an approximate
200 degree arc of the horizon at one glance, only a
very small center area called the fovea, in the rear of
the eye, has the ability to send clear, sharply focused
messages to the brain. All other visual informationthat is not processed directly through the fovea will be
of less detail. An aircraft at a distance of 7 miles
which appears in sharp focus within the foveal center
of vision would have to be as close as
7/10 of a mile
in order to be recognized if it were outside of foveal
vision. Because the eyes can focus only on thisnarrow viewing area, effective scanning is accom-
plished with a series of short, regularly spaced eye
movements that bring successive areas of the sky into
the central visual field. Each movement should not
exceed 10 degrees, and each area should be observed
for at least 1 second to enable detection. Althoughhorizontal back-and-forth eye movements seem
preferred by most pilots, each pilot should develop a
scanning pattern that is most comfortable and thenadhere to it to assure optimum scanning.
3.Studies show that the time a pilot spends on
visual tasks inside the cabin should represent no more
that
1/4 to 1/3 of the scan time outside, or no more than
4 to 5 seconds on the instrument panel for every16 seconds outside. Since the brain is already trained
to process sight information that is presented from
left to right, one may find it easier to start scanningover the left shoulder and proceed across the
windshield to the right.
4.Pilots should realize that their eyes may
require several seconds to refocus when switching
views between items in the cockpit and distantobjects. The eyes will also tire more quickly when
forced to adjust to distances immediately after
close-up focus, as required for scanning theinstrument panel. Eye fatigue can be reduced by
looking from the instrument panel to the left wing
past the wing tip to the center of the first scan quadrant
when beginning the exterior scan. After having
scanned from left to right, allow the eyes to return to
the cabin along the right wing from its tip inward.Once back inside, one should automatically com-
mence the panel scan.
5.Effective scanning also helps avoid “empty-
field myopia.” This condition usually occurs when
flying above the clouds or in a haze layer thatprovides nothing specific to focus on outside the
aircraft. This causes the eyes to relax and seek a
AIM 10/12/17
8−1−8 Fitness for Flightcomfortable focal distance which may range from
10 to 30 feet. For the pilot, this means looking
without seeing, which is dangerous.
8−1−7. Aerobatic Flight
a.Pilots planning to engage in aerobatics should
be aware of the physiological stresses associated with
accelerative forces during aerobatic maneuvers.
Many prospective aerobatic trainees enthusiasticallyenter aerobatic instruction but find their first
experiences with G forces to be unanticipated and
very uncomfortable. To minimize or avoid potentialadverse effects, the aerobatic instructor and trainee
must have a basic understanding of the physiology of
G force adaptation.
b.Forces experienced with a rapid push-over
maneuver result in the blood and body organs being
displaced toward the head. Depending on forcesinvolved and individual tolerance, a pilot may
experience discomfort, headache, “red-out,” and
even unconsciousness.
c.Forces experienced with a rapid pull-up
maneuver result in the blood and body organ
displacement toward the lower part of the body away
from the head. Since the brain requires continuous
blood circulation for an adequate oxygen supply,
there is a physiologic limit to the time the pilot cantolerate higher forces before losing consciousness.
As the blood circulation to the brain decreases as a
result of forces involved, a pilot will experience“narrowing” of visual fields, “gray-out,” “black-
out,” and unconsciousness. Even a brief loss of
consciousness in a maneuver can lead to improper
control movement causing structural failure of the
aircraft or collision with another object or terrain.
d.In steep turns, the centrifugal forces tend to
push the pilot into the seat, thereby resulting in blood
and body or gan displacement toward the lower part of
the body as in the case of rapid pull-up maneuvers andwith the same physiologic effects and symptoms.
e.Physiologically, humans progressively adapt to
imposed strains and stress, and with practice, anymaneuver will have decreasing effect. Tolerance to
G forces is dependent on human physiology and the
individual pilot. These factors include the skeletalanatomy, the cardiovascular architecture, the nervous
system, the quality of the blood, the general physical
state, and experience and recency of exposure. Thepilot should consult an Aviation Medical Examiner
prior to aerobatic training and be aware that poor
physical condition can reduce tolerance to accelera-
tive forces.
f.The above information provides pilots with a
brief summary of the physiologic effects of G forces.
It does not address methods of “counteracting” these
effects. There are numerous references on the subject
of G forces during aerobatics available to pilots.Among these are “G Effects on the Pilot During
Aerobatics,” FAA −AM−72−28, and “G Incapacita-
tion in Aerobatic Pilots: A Flight Hazard”
FAA−AM−82−13. These are available from the
National Technical Information Service, Springfield,
Virginia 22161.
REFERENCE −
FAA AC 91 −61, A Hazard in Aerobatics: Effects of G −forces on Pilots.
8−1−8. Judgment Aspects of Collision
Avoidance
a. Introduction. The most important aspects of
vision and the techniques to scan for other airc raft are
described in paragraph 8 −1−6, Vision in Flight. Pilots
should also be familiar with the following informa-
tion to reduce the possibility of mid-air collisions.
b. Determining Relative Altitude. Use the
horizon as a reference point. If the other aircraft is
above the horizon, it is probably on a higher flightpath. If the aircraft appears to be below the horizon,
it is probably flying at a lower altitude.
c. Taking Appropriate Action. Pilots should be
familiar with rules on right-of-way, so if an aircraft is
on an obvious collision course, one can take
immediate evasive action, preferably in compliancewith applicable Federal Aviation Regulations.
d. Consider Multiple Threats. The decision to
climb, descend, or turn is a matter of personal
judgment, but one should anticipate that the other
pilot may also be making a quick maneuver. Watch
the other aircraft during the maneuver and begin yourscanning again immediately since there may be other
aircraft in the area.
e. Collision Course Targets. Any aircraft that
appears to have no relative motion and stays in onescan quadrant is likely to be on a collision course.
Also, if a target shows no lateral or vertical motion,
but increases in size, take evasive action.
AIM 10/12/17
8−1−9 Fitness for Flightf. Recognize High Hazard Areas.
1.Airways, especially near VORs, and Class B,
Class C, Class D, and Class E surface areas are places
where aircraft tend to cluster.
2.Remember, most collisions occur during days
when the weather is good. Being in a “radar
environment” still requires vigilance to avoid
collisions.
g. Cockpit Management. Studying maps,
checklists, and manuals before flight, with other
proper preflight planning; e.g., noting necessary
radio frequencies and organizing cockpit materials,can reduce the amount of time required to look at
these items during flight, permitting more scan time.
h. Windshield Conditions. Dirty or bug-
smeared windshields can greatly reduce the ability of
pilots to see other aircraft. Keep a clean windshield.
i. Visibility Conditions. Smoke, haze, dust, rain,
and flying towards the sun can also greatly reduce the
ability to detect targets.j. Visual Obstructions in the Cockpit.
1.Pilots need to move their heads to see around
blind spots caused by fixed aircraft structures, such as
door posts, wings, etc. It will be necessary at times to
maneuver the aircraft; e.g., lift a wing, to facilitate
seeing.
2.Pilots must ensure curtains and other cockpit
objects; e.g., maps on glare shield, are removed and
stowed during flight.
k. Lights On.
1.Day or night, use of exterior lights can greatly
increase the conspicuity of any aircraft.
2.Keep interior lights low at night.
l. ATC Support. ATC facilities often provide
radar traffic advisories on a workload-permittingbasis. Flight through Class C and Class D airspace
requires communication with ATC. Use this support
whenever possible or when required.
AIM 10/12/17
9−1−1 Types of Charts AvailableChapter 9. Aeronautical Charts and
Related Publications
Section 1. Types of Charts Available
9−1−1. General
Civil aeronautical charts for the U.S. and its
territories, and possessions are produced by
Aeronautical Information Services (AIS),
http://www.faa.gov/air_tra ffic/flight_info/aeronav
which is part of FAA’s Air Traffic Organization,
Mission Support Services.
9−1−2. Obtaining Aeronautical Charts
Public sales of charts and publications are available
through a network of FAA approved print providers.
A listing of products, dates of latest editions and
agents is available on the AIS website at:http://www.faa.gov/air_traffic/flight_info/aeronav.
9−1−3. Selected Charts and Products
Available
VFR Navigation Charts
IFR Navigation ChartsPlanning Charts
Supplementary Charts and Publications
Digital Products
9−1−4. General Description of Each Chart
Series
a. VFR Navigation Charts.
1. Sectional Aeronautical Charts. Sectional
Charts are designed for visual navigation of slow tomedium speed aircraft. The topographic information
consists of contour lines, shaded relief, drainage
patterns, and an extensive selection of visualcheckpoints and landmarks used for flight under
VFR. Cultural features include cities and towns,roads, railroads, and other distinct landmarks. The
aeronautical information includes visual and radio
aids to navigation, airports, controlled airspace,
special−use airspace, obstructions, and related data.
Scale 1 inch = 6.86 nm/1:500,000. 60 x 20 inchesfolded to 5 x 10 inches. Revised biannually, except
most Alaskan charts are revised annually.
(See FIG 9−1−1 and FIG 9−1−2.)
2. VFR Terminal Area Charts (TAC). TACs
depict the airspace designated as Class B airspace.
While similar to sectional charts, TACs have more
detail because the scale is larger. The TAC should be
used by pilots intending to operate to or from airfields
within or near Class B or Class C airspace. Areas with
TAC coverage are indicated by a • on the Sectional
Chart indexes. Scale 1 inch = 3.43 nm/1:250,000.
Charts are revised biannually, except Puerto
Rico−Virgin Islands which is revised annually.
(See FIG 9−1−1 and FIG 9−1−2.)
3. U.S. Gulf Coast VFR Aeronautical Chart.
The Gulf Coast Chart is designed primarily for
helicopter operation in the Gulf of Mexico area.Information depicted includes offshore mineral
leasing areas and blocks, oil drilling platforms, and
high density helicopter activity areas. Scale 1 inch =13.7 nm/1:1,000,000. 55 x 27 inches folded to
5 x 10 inches. Revised annually.
4. Grand Canyon VFR Aeronautical Chart.
Covers the Grand Canyon National Park area and is
designed to promote aviation safety, flight free zones,
and facilitate VFR navigation in this popular area.
The chart contains aeronautical information forgeneral aviation VFR pilots on one side and
commercial VFR air tour operators on the other side.
AIM 10/12/17
9−1−2 Types of Charts AvailableFIG 9−1−1
Sectional and VFR Terminal Area Charts for the Conterminous U.S.,
Hawaii, Puerto Rico, and Virgin Islands
FIG 9−1−2
Sectional and VFR Terminal Area Charts for Alaska
AIM 10/12/17
9−1−3 Types of Charts Available5. Caribbean VFR Aeronautical Charts.
Caribbean 1 and 2 (CAC−1 and CAC −2) are designed
for visual navigation to assist familiarization of
foreign aeronautical and topographic information.
The aeronautical information includes visual andradio aids to navigation, airports, controlled airspace,
special−use airspace, obstructions, and related data.
The topographic information consists of contourlines, shaded relief, drainage patterns, and a selection
of landmarks used for flight under VFR. Cultural
features include cities and towns, roads, railroads,
and other distinct landmarks. Scale 1 inch =
13.7 nm/1:1,000,000. CAC −1, revised annually,
consists of two sides measuring 30” x 60” each.
CAC−2, revised biennially, consists of two sides
measuring 20” x 60” each. (See FIG 9−1−3.)
FIG 9−1−3
Caribbean VFR Aeronautical Charts
AIM 10/12/17
9−1−4 Types of Charts Available6. Helicopter Route Charts. A three−color
chart series which shows current aeronautical
information useful to helicopter pilots navigating in
areas with high concentrations of helicopter activity.
Information depicted includes helicopter routes, four
classes of heliports with associated frequency and
lighting capabilities, NA V AIDs, and obstructions. Inaddition, pictorial symbols, roads, and easily
identified geographical features are portrayed.
Helicopter charts have a longer life span than other
chart products and may be current for several years.
Helicopter Route Charts are updated as requested by
the FAA. Scale 1 inch = 1.71 nm/1:125,000. 34 x 30
inches folded to 5 x 10 inches. (See FIG 9−1−4.)
FIG 9−1−4
Helicopter Route Charts
b. IFR Navigation Charts.
1. IFR En Route Low Altitude Charts
(Conterminous U.S. and Alaska). En route low
altitude charts provide aeronautical information fornavigation under IFR conditions below 18,000 feet
MSL. This four −color chart series includes airways;
limits of controlled airspace; VHF NA V AIDs withfrequency, identification, channel, geographic coor-
dinates; airports with terminal air/groundcommunications; minimum en route and obstruction
clearance altitudes; airway distances; reporting
points; special use airspace; and military training
routes. Scales vary from 1 inch = 5nm to 1 inch =
20 nm. 50 x 20 inches folded to 5 x 10 inches. Chartsrevised every 56 days. Area charts show congested
terminal areas at a large scale. They are included with
subscriptions to any conterminous U.S. Set Low (Full
set, East or West sets).
(See FIG 9−1−5 and FIG 9−1−6.)
AIM 10/12/17
9−1−5 Types of Charts AvailableFIG 9−1−5
En Route Low Altitude Instrument Charts for the Conterminous U.S. (Includes Area Charts)
FIG 9−1−6
Alaska En Route Low Altitude Chart
AIM 10/12/17
9−1−6 Types of Charts Available2. IFR En Route High Altitude Charts
(Conterminous U.S. and Alaska). En route high
altitude charts are designed for navigation at or above
18,000 feet MSL. This four −color chart series
includes the jet route structure; VHF NA V AIDs withfrequency, identification, channel, geographic coor-
dinates; selected airports; reporting points. Scales
vary from 1 inch = 45 nm to 1 inch = 18 nm. 55 x 20
inches folded to 5 x 10 inches. Revised every 56 days.
(See FIG 9−1−7 and FIG 9−1−8.)
FIG 9−1−7
En Route High Altitude Charts for the Conterminous U.S.
FIG 9−1−8
Alaskan En Route High Altitude Chart
AIM 10/12/17
9−1−7 Types of Charts Available3. U.S. Terminal Procedures Publication
(TPP). TPPs are published in 24 loose −leaf or
perfect bound volumes covering the conterminous
U.S., Puerto Rico and the Virgin Islands. A Change
Notice is published at the midpoint between revisions
in bound volume format and is available on the
internet for free download at the AIS website. (See
FIG 9−1−15.) The TPPs include:
(a) Instrument Appr oach Pr ocedure (IAP)
Charts. IAP charts portray the aeronautical data that
is required to execute instrument approaches to
airports. Each chart depicts the IAP, all relatednavigation data, communications information, and an
airport sketch. Each procedure is designated for use
with a specific electronic navigational aid, such asILS, VOR, NDB, RNA V , etc.
(b) Instrument Departure Procedure (DP)
Charts. DP charts are designed to expedite
clearance delivery and to facilitate transition between
takeoff and en route operations. They furnish pilots’
departure routing clearance information in graphic
and textual form.
(c) Standard Terminal Arrival (STAR)
Charts. STAR charts are designed to expedite ATC
arrival procedures and to facilitate transition between
en route and instrument approach operations. Theydepict preplanned IFR ATC arrival procedures in
graphic and textual form. Each STAR procedure is
presented as a separate chart and may serve either asingle airport or more than one airport in a given
geographic area.
(d) Airport Diagrams. Full page airport
diagrams are designed to assist in the movement ofground traffic at locations with complex runway/taxi-
way configurations and provide information for
updating geodetic position navigational systemsaboard aircraft. Airport diagrams are available for
free download at the AIS website.
4. Alaska Terminal Procedures Publication.
This publication contains all terminal flight proce-dures for civil and military aviation in Alaska.Included are IAP charts, DP charts, STAR charts,
airport diagrams, radar minimums, and supplemen-
tary support data such as IFR alternate minimums,
take−off minimums, rate of descent tables, rate of
climb tables and inoperative components tables.V olume is 5 −3/8 x 8−1/4 inch top bound. Publication
revised every 56 days with provisions for a Terminal
Change Notice, as required.
c. Planning Charts.
1. U.S. IFR/VFR Low Altitude Planning
Chart. This chart is designed for prefight and
en route flight planning for IFR/VFR flights.
Depiction includes low altitude airways and mileage,
NA V AIDs, airports, special use airspace, cities, times
zones, major drainage, a directory of airports with
their airspace classification, and a mileage table
showing great circle distances between majorairports. Scale 1 inch = 47nm/1:3,400,000. Chart
revised annually, and is available either folded or
unfolded for wall mounting. (See FIG 9−1−10.)
2. Gulf of Mexico and Caribbean Planning
Chart. This is a VFR planning chart on the reverse
side of the
Puerto Rico − V irgin Islands VFR T erminal
Area Chart. Information shown includes mileage
between airports of entry, a selection of special use
airspace and a directory of airports with their
available services. Scale 1 inch = 85nm/1:6,192,178.
60 x 20 inches folded to 5 x 10 inches. Chart revisedannually. (See FIG 9−1−10.)
3. Alaska VFR Wall Planning Chart. This
chart is designed for VFR preflight planning andchart selection. It includes aeronautical and topo-
graphic information of the state of Alaska. The
aeronautical information includes public and military
airports; radio aids to navigation; and Class B, Class
C, TRSA and special −use airspace. The topographic
information includes city tint, populated places,principal roads, and shaded relief. Scale 1 inch =
27.4 nm/1:2,000,000. The one sided chart is 58.5 x
40.75 inches and is designed for wall mounting. Chart
is revised biennially. (See FIG 9−1−9.)
AIM 10/12/17
9−1−8 Types of Charts AvailableFIG 9−1−9
Alaska VFR Wall Planning Chart
FIG 9−1−10
Planning Charts
AIM 10/12/17
9−1−9 Types of Charts Available4. U.S. VFR Wall Planning Chart. This chart
is designed for VFR preflight planning and chart
selection. It includes aeronautical and topographic
information of the conterminous U.S. The aeronauti-
cal information includes airports, radio aids tonavigation, Class B airspace and special use airspace.
The topographic information includes city tint,
populated places, principal roads, drainage patterns,and shaded relief. Scale 1 inch = 43 nm/ 1:3,100,000.
The one-sided chart is 59 x 36 inches and ships
unfolded for wall mounting. Chart is revisedbiennially. (See FIG 9−1−11.)
FIG 9−1−11
U.S. VFR Wall Planning Chart
5. Charted VFR Flyway Planning Charts.
This chart is printed on the reverse side of selected
TAC charts. The coverage is the same as theassociated T AC. Flyway planning charts depict flight
paths and altitudes recommended for use to bypass
high traffic areas. Ground references are provided asa guide for visual orientation. Flyway planning charts
are designed for use in conjunction with TACs and
sectional charts and are not to be used for navigation.
Chart scale 1 inch = 3.43 nm/1:250,000.
d. Supplementary Charts and Publications.
1. Chart Supplement U.S. This 7−volume
booklet series contains data on airports, seaplane
bases, heliports, NA V AIDs, communications data,
weather data sources, airspace, special notices, andoperational procedures. Coverage includes the
conterminous U.S., Puerto Rico, and the VirginIslands. The Chart Supplement U.S. shows data that
cannot be readily depicted in graphic form; for
example, airport hours of operations, types of fuel
available, runway widths, lighting codes, etc. The
Chart Supplement U.S. also provides a means forpilots to update visual charts between edition dates
(The Chart Supplement U.S. is published every 56
days while Sectional Aeronautical and VFR T erminal
Area Charts are generally revised every six months).
The Aeronautical Chart Bulletins (VFR Chart Update
Bulletins) are available for free download at the AIS
website. V olumes are side −bound 5−3/8 x 8−1/4
inches. (See FIG 9−1−14.)
2. Chart Supplement Alaska. This is a
civil/military flight information publication issued by
FAA every 56 days. It is a single volume booklet
designed for use with appropriate IFR or VFR charts.
The Chart Supplement Alaska contains airportsketches, communications data, weather data
sources, airspace, listing of navigational facilities,
and special notices and procedures. V olume isside−bound 5−3/8 x 8−1/4 inches.
3. Chart Supplement Pacific. This supple-
ment is designed for use with appropriate VFR or IFR
en route charts. Included in this one −volume booklet
are the chart supplement, communications data,
weather data sources, airspace, navigational facili-
ties, special notices, and Pacific area procedures. IAP
charts, DP charts, STAR charts, airport diagrams,
radar minimums, and supporting data for the
Hawaiian and Pacific Islands are included. Themanual is published every 56 days. V olume is
side−bound 5−3/8 x 8−1/4 inches.
4. North Atlantic Route Chart. Designed for
FAA controllers to monitor transatlantic flights, this5−color chart shows oceanic control areas, coastal
navigation aids, oceanic reporting points, and
NA V AID geographic coordinates. Full Size Chart:Scale 1 inch = 113.1 nm/1:8,250,000. Chart is
shipped flat only. Half Size Chart: Scale 1 inch =
150.8 nm/1:11,000,000. Chart is 29 −3/4 x
20−1/2 inches, shipped folded to 5 x 10 inches only.
Chart revised every 56 weeks. (See
FIG 9−1−12.)
AIM 10/12/17
9−1−10 Types of Charts AvailableFIG 9−1−12
North Atlantic Route Charts
5. North Pacific Route Charts. These charts
are designed for FAA controllers to monitor
transoceanic flights. They show established intercon-
tinental air routes, including reporting points with
geographic positions. Composite Chart: Scale
1 inch = 164 nm/1:12,000,000. 48 x 41 −1/2 inches.
Area Charts: Scale 1 inch = 95.9 nm/1:7,000,000.
52 x 40−1/2 inches. All charts shipped unfolded.
Charts revised every 56 days. (See FIG 9−1−13.)
FIG 9−1−13
North Pacific Oceanic Route Charts
6. Airport Obstruction Charts (OC). The
OC is a 1:12,000 scale graphic depicting 14 CFR
Part 77, Objects Affecting Navigable Airspace ,
surfaces, a representation of objects that penetrate
these surfaces, aircraft movement and apron areas,navigational aids, prominent airport buildings, and a
selection of roads and other planimetric detail in the
airport vicinity. Also included are tabulations ofrunway and other operational data.
7. FAA Aeronautical Chart User’s Guide.
A booklet designed to be used as a teaching aid andreference document. It describes the substantial
amount of information provided on FAA’s aeronauti-
cal charts and publications. It includes explanationsand illustrations of chart terms and symbols
organized by chart type. The users guide is available
for free download at the AIS website.
e. Digital Products.
1. The Digital Aeronautical Information CD
(DAICD). The DAICD is a combination of the
NA V AID Digital Data File, the Digital ChartSupplement, and the Digital Obstacle File on one
Compact Disk. These three digital products are no
longer sold separately. The files are updated every56 days and are available by subscription only.
(a) The NA V AID Digital Data File. This
file contains a current listing of NA V AIDs that arecompatible with the National Airspace System. This
file contains all NA V AIDs including ILS and its
components, in the U.S., Puerto Rico, and the Virgin
Islands plus bordering facilities in Canada, Mexico,
and the Atlantic and Pacific areas.
(b) The Digital Obstacle File. This file
describes all obstacles of interest to aviation users in
the U.S., with limited coverage of the Pacific,Caribbean, Canada, and Mexico. The obstacles are
assigned unique numerical identifiers, accuracy
codes, and listed in order of ascending latitude within
each state or area.
(c) The Digital Aeronautical Chart Supple-
ment (DACS). The DACS is specifically designed
to provide digital airspace data not otherwise readily
available. The supplement includes a Change Notice
for IAPFIX.dat at the mid −point between revisions.
The Change Notice is available only by free
download at the AIS website.
AIM 10/12/17
9−1−11 Types of Charts AvailableThe DACS individual data files are:
ENHIGH.DAT: High altitude airways (contermi-
nous U.S.)
ENLOW.DAT: Low altitude airways (conterminousU.S.)
IAPFIX.DAT: Selected instrument approach proce-
dure NA V AID and fix data.
MTRFIX.DAT: Military training routes data.
ALHIGH.DAT: Alaska high altitude airways data.ALLOW.DAT: Alaska low altitude airways data.
PR.DAT: Puerto Rico airways data.
HAWAII.DAT: Hawaii airways data.BAHAMA.DAT: Bahamas routes data.
OCEANIC.DAT: Oceanic routes data.
STARS.DAT: Standard terminal arrivals data.DP.DAT: Instrument departure procedures data.
LOPREF.DAT: Preferred low altitude IFR routes
data.HIPREF.DAT: Preferred high altitude IFR routes
data.
ARF.DAT: Air route radar facilities data.ASR.DAT: Airport surveillance radar facilities data.
2. The Coded Instrument Flight Procedures
(CIFP) (ARINC 424 [Ver 13 & 15]). The CIFP is a
basic digital dataset, modeled to an internationalstandard, which can be used as a basis to support GPS
navigation. Initial data elements included are: Airport
and Helicopter Records, VHF and NDB Navigation
aids, en route waypoints and airways. Additional data
elements will be added in subsequent releases toinclude: departure procedures, standard terminal
arrivals, and GPS/RNA V instrument approach
procedures. The database is updated every 28 days.The data is available by subscription only and is
distributed on CD −ROM or by ftp download.
3. digital −Visual Charts (d −VC). These digi-
tal VFR charts are geo −referenced images of FAA
Sectional Aeronautical, TAC, and Helicopter Routecharts. Additional digital data may easily be overlaid
on the raster image using commonly available
Geographic Information System software. Data such
as weather, temporary flight restrictions, obstacles, or
other geospatial data can be combined with d −VC
data to support a variety of needs. The file resolution
is 300 dots per inch and the data is 8 −bit color. The
data is provided as a GeoTIFF and distributed on
DVD−R media and on the AIS website. The root
mean square error of the transformation will not
exceed two pixels. Digital −VC DVDs are updated
every 28 days and are available by subscription only.
FIG 9−1−14
Chart Supplement U.S. Geographic Areas
AIM 10/12/17
9−1−12 Types of Charts AvailableFIG 9−1−15
U.S. Terminal Publication Volumes
AIM 10/12/17
9−1−13 Types of Charts Available9−1−5. Where and How to Get Charts of
Foreign Areas
a. National Geospatial −Intelligence Agency
(NGA) Products. For the latest information regard-
ing publication availability visit the NGA website:https://www.nga.mil/ProductsServices/Pages/de-
fault.aspx.
1. Flight Information Publication (FLIP)
Planning Documents.
General Planning (GP)
Area Planning
Area Planning − Special Use Airspace −
Planning Charts
2. FLIP En Route Charts and Chart
Supplements.
Pacific, Australasia, and Antarctica
U.S. − IFR and VFR Supplements
Flight Information HandbookCaribbean and South America − Low Altitude
Caribbean and South America − High Altitude
Europe, North Africa, and Middle East −
Low Altitude
Europe, North Africa, and Middle East −
High Altitude
Africa
Eastern Europe and Asia
Area Arrival Charts
3. FLIP Instrument Approach Procedures
(IAPs).
Africa
Canada and North Atlantic
Caribbean and South AmericaEastern Europe and Asia
Europe, North Africa, and Middle East
Pacific, Australasia, and AntarcticaVFR Arrival/Departure Routes − Europe and Korea
U.S.
4. Miscellaneous DOD Charts and Products.
Aeronautical Chart Updating Manual (CHUM)
DOD Weather Plotting Charts (WPC)Tactical Pilotage Charts (TPC)
Operational Navigation Charts (ONC)
Global Navigation and Planning Charts (GNC)Jet Navigation Charts (JNC) and Universal Jet
Navigation Charts (JNU)
Jet Navigation Charts (JNCA)
Aerospace Planning Charts (ASC)
Oceanic Planning Charts (OPC)Joint Operations Graphics − Air (JOG −A)
Standard Index Charts (SIC)
Universal Plotting Sheet (VP −OS)
Sight Reduction Tables for Air Navigation (PUB249)
Plotting Sheets (VP −30)
Dial−Up Electronic CHUM
b. Canadian Charts. Information on available
Canadian charts and publications may be obtained by
contacting the:
NA V CANADA
Aeronautical Publications
Sales and Distribution UnitP.O. Box 9840, Station T
Ottawa, Ontario K1G 6S8 Canada
Telephone: 613 −744−6393 or 1 −866−
731−7827
Fax: 613−744−7120 or 1−866−740−9992
c. Mexican Charts. Information on available
Mexican charts and publications may be obtained by
contacting:
Dirección de Navigacion Aereo
Blvd. Puerto Aereo 485Zona Federal Del Aeropuerto Int’l
15620 Mexico D.F.
Mexico
d. International Civil Aviation Organization
(ICAO). A free ICAO Publications and Audio −
Visual Training Aids Catalogue is available from:
International Civil Aviation Organization
ATTN: Document Sales Unit
999 University StreetMontreal, Quebec
H3C 5H7, Canada
Telephone: (514) 954 −8022
Fax: (514) 954 −6769
E−mail: sales_unit@icao.org
Internet: http://www.icao.org/cgi/goto.pl?icao/en/
sales.htm
Sitatex: YULCAYA
Telex: 05−24513
AIM 10/12/17
10−1−1 Helicopter IFR OperationsChapter 10. Helicopter Operations
Section 1. Helicopter IFR Operations
10−1−1. Helicopter Flight Control Systems
a.The certification requirements for helicopters to
operate under Instrument Flight Rules (IFR) are
contained in 14 CFR Part 27, AirworthinessStandards: Normal Category Rotorcraft, and 14 CFR
Part 29, Airworthiness Standards: Transport
Category Rotorcraft. To meet these requirements,helicopter manufacturers usually utilize a set of
stabilization and/or Automatic Flight Control
Systems (AFCSs).
b.Typically, these systems fall into the following
categories:
1.Aerodynamic surfaces, which impart some
stability or control capability not found in the basic
VFR configuration.
2.Trim systems, which provide a cyclic
centering effect. These systems typically involve amagnetic brake/spring device, and may also be
controlled by a four −way switch on the cyclic. This
is a system that supports “hands on” flying of thehelicopter by the pilot.
3.Stability Augmentation Systems (SASs),
which provide short −term rate damping control
inputs to increase helicopter stability. Like trim
systems, SAS supports “hands on” flying.
4.Attitude Retention Systems (ATTs), which
return the helicopter to a selected attitude after a
disturbance. Changes in desired attitude can beaccomplished usually through a four −way “beep”
switch, or by actuating a “force trim” switch on the
cyclic, setting the attitude manually, and releasing.Attitude retention may be a SAS function, or may be
the basic “hands off” autopilot function.
5.Autopilot Systems (APs), which provide for
“hands off” flight along specified lateral and vertical
paths, including heading, altitude, vertical speed,
navigation tracking, and approach. These systemstypically have a control panel for mode selection, and
system for indication of mode status. Autopilots may
or may not be installed with an associated Flight
Director System (FD). Autopilots typically control
the helicopter about the roll and pitch axes (cycliccontrol) but may also include yaw axis (pedal control)
and collective control servos.
6.FDs, which provide visual guidance to the
pilot to fly specific selected lateral and vertical modes
of operation. The visual guidance is typically
provided as either a “dual cue” (commonly known as
a “cross−pointer”) or “single cue” (commonly known
as a “vee−bar”) presentation superimposed over the
attitude indicator. Some FDs also include a collective
cue. The pilot manipulates the helicopter’s controls to
satisfy these commands, yielding the desired flight
path, or may couple the flight director to the autopilot
to perform automatic flight along the desired flightpath. Typically, flight director mode control and
indication is shared with the autopilot.
c.In order to be certificated for IFR operation, a
specific helicopter may require the use of one or more
of these systems, in any combination.
d.In many cases, helicopters are certificated for
IFR operations with either one or two pilots. Certain
equipment is required to be installed and functionalfor two pilot operations, and typically, additional
equipment is required for single pilot operation.
These requirements are usually described in thelimitations section of the Rotorcraft Flight Manual
(RFM).
e.In addition, the RFM also typically defines
systems and functions that are required to be inoperation or engaged for IFR flight in either the single
or two pilot configuration. Often, particularly in two
pilot operation, this level of augmentation is less than
the full capability of the installed systems. Likewise,
single pilot operation may require a higher level of
augmentation.
AIM 10/12/17
10−1−2 Helicopter IFR Operationsf.The RFM also identifies other specific limita-
tions associated with IFR flight. Typically, these
limitations include, but are not limited to:
1.Minimum equipment required for IFR flight
(in some cases, for both single pilot and two pilotoperations).
2.Vmini (minimum speed − IFR).
NOTE−
The manufacturer may also recommend a minimum IFRairspeed during instrument approach.
3.Vnei (never exceed speed − IFR).
4.Maximum approach angle.
5.Weight and center of gravity limits.
6.Aircraft configuration limitations (such as
aircraft door positions and external loads).
7.Aircraft system limitations (generators,
inverters, etc.).
8.System testing requirements (many avionics
and AFCS/AP/FD systems incorporate a self −test
feature).
9.Pilot action requirements (such as the pilot
must have his/her hands and feet on the controls
during certain operations, such as during instrument
approach below certain altitudes).
g.It is very important that pilots be familiar with
the IFR requirements for their particular helicopter.
Within the same make, model and series of helicopter,
variations in the installed avionics may change therequired equipment or the level of augmentation for
a particular operation.
h.During flight operations, pilots must be aware
of the mode of operation of the augmentation
systems, and the control logic and functionsemployed. For example, during an ILS approach
using a particular system in the three −cue mode
(lateral, vertical and collective cues), the flightdirector collective cue responds to glideslope
deviation, while the horizontal bar of the “cross −
pointer” responds to airspeed deviations. The same
system, while flying an ILS in the two −cue mode,
provides for the horizontal bar to respond to
glideslope deviations. This concern is particularly
significant when operating using two pilots. Pilots
should have an established set of procedures andresponsibilities for the control of flight director/auto-
pilot modes for the various phases of flight. Not only
does a full understanding of the system modesprovide for a higher degree of accuracy in control of
the helicopter, it is the basis for crew identification of
a faulty system.
i.Relief from the prohibition to takeoff with any
inoperative instruments or equipment may be
provided through a Minimum Equipment List (see14 CFR Section 91.213 and 14 CFR Section 135.179,
Inoperative Instruments and Equipment). In many
cases, a helicopter configured for single pilot IFRmay depart IFR with certain equipment inoperative,
provided a crew of two pilots is used. Pilots are
cautioned to ensure the pilot −in−command and
second−in−command meet the requirements of
14 CFR Section 61.58, Pilot −in−Command Profi-
ciency Check: Operation of Aircraft Requiring More
Than One Pilot Flight Crewmember, and 14 CFR
Section 61.55, Second −in−Command Qualifications,
or 14 CFR Part 135, Operating Requirements:
Commuter and On −Demand Operations, Subpart E,
Flight Crewmember Requirements, and Subpart G,Crewmember Testing Requirements, as appropriate.
j.
Experience has shown that modern AFCS/AP/
FD equipment installed in IFR helicopters can, insome cases, be very complex. This complexity
requires the pilot(s) to obtain and maintain a high
level of knowledge of system operation, limitations,failure indications and reversionary modes. In some
cases, this may only be reliably accomplished
through formal training.
AIM 10/12/17
10−1−3 Helicopter IFR Operations10−1−2. Helicopter Instrument Approaches
a.Helicopters are capable of flying any published
14 CFR Part 97, Standard Instrument Approach
Procedures (SIAPs), for which they are properlyequipped, subject to the following limitations and
conditions:
1.Helicopters flying conventional (non −
Copter) SIAPs may reduce the visibility minima to
not less than one half the published Category A
landing visibility minima, or
1/4 statute mile
visibility/1200 RVR, whichever is greater unless the
procedure is annotated with “ Visibility Reduction
by Helicopters NA .” This annotation means that
there are penetrations of the final approach obstacle
identification surface (OIS) and that the 14 CFR
Section 97.3 visibility reduction rule does not applyand you must take precaution to avoid any obstacles
in the visual segment. No reduction in MDA/DA is
permitted. The helicopter may initiate the finalapproach segment at speeds up to the upper limit of
the highest approach category authorized by the
procedure, but must be slowed to no more than
90 KIAS at the missed approach point (MAP) in
order to apply the visibility reduction. Pilots arecautioned that such a decelerating approach may
make early identification of wind shear on the
approach path dif ficult or impossible. If required, use
the Inoperative Components and Visual Aids Table
provided in the front cover of the U.S. Terminal
Procedures V olume to derive the Category A minima
before applying the 14 CFR Section 97.3(d −1) rule.
2.Helicopters flying Copter SIAPs may use the
published minima, with no reductions allowed. Themaximum airspeed is 90 KIAS on any segment of the
approach or missed approach.
3.Helicopters flying GPS Copter SIAPs must
limit airspeed to 90 KIAS or less when flying any
segment of the procedure, except speeds must be
limited to no more than 70 KIAS on the final andmissed approach segments. Military GPS Copter
SIAPs are limited to no more than 90 KIAS
throughout the procedure. If annotated, holding mayalso be limited to no more than 70 KIAS. Use the
published minima, no reductions allowed.
NOTE−
Obstruction clearance surfaces are based on the aircraft
speed and have been designed on these approaches for
70 knots. If the helicopter is flown at higher speeds, it may
fly outside of protected airspace. Some helicopters have aV
MINI greater than 70 knots; therefore, they cannot meet
the 70 knot limitation to conduct this type of procedure.
Some helicopter autopilots, when used in the “go −around”
mode, are programmed with a V YI greater than 70 knots,
therefore when using the autopilot “go −around” mode,
they cannot meet the 70 knot limitation to conduct this type
of approach. It may be possible to use the autopilot for the
missed approach in the other than the “go−around” mode
and meet the 70 knot limitation to conduct this type ofapproach. When operating at speeds other than V
YI or V Y,
performance data may not be available in the RFM topredict compliance with climb gradient requirements.
Pilots may use observed performance in similar
weight/altitude/temperature/speed conditions to evaluatethe suitability of performance. Pilots are cautioned tomonitor climb performance to ensure compliance withprocedure requirements.
4.TBL 10−1−1 summarizes these require-
ments.
5.Even with weather conditions reported at or
above landing minima, some combinations of
reduced cockpit cutoff angle, minimal approach/runway lighting, and high MDA/DH coupled with a
low visibility minima, the pilot may not be able to
identify the required visual reference(s) during theapproach, or those references may only be visible in
a very small portion of the pilot’s available field of
view. Even if identified by the pilot, these visualreferences may not support normal maneuvering and
normal rates of descent to landing. The effect of such
a combination may be exacerbated by otherconditions such as rain on the windshield, or
incomplete windshield defogging coverage.
6.Pilots are cautioned to be prepared to execute
a missed approach even though weather conditionsmay be reported at or above landing minima.
NOTE−
See paragraph 5 −4−21, Missed Approach, for additional
information on missed approach procedures.
AIM 10/12/17
10−1−4 Helicopter IFR OperationsTBL 10−1−1
Helicopter Use of Standard Instrument Approach Procedures
Procedure Helicopter Visibility
MinimaHelicopter MDA/DA Maximum Speed Limitations
Conventional(non−Copter) The greater of: one half
the Category A visibility
minima, 1/4 statute mile
visibility, or 1200 RVRAs published forCategory A The helicopter may initiate the finalapproach segment at speeds up to
the upper limit of the highest
Approach Category authorized bythe procedure, but must be slowedto no more than 90 KIAS at the
MAP in order to apply the visibility
reduction.
Copter Procedure As published As published 90 KIAS when on a publishedroute/track.
GPS Copter Procedure As published As published 90 KIAS when on a published routeor track, EXCEPT 70 KIAS when
on the final approach or missed
approach segment and, if annotated,in holding. Military procedures arelimited to 90 KIAS for all segments.
NOTE−
Several factors affect the ability of the pilot to acquire and
maintain the visual references specified in 14 CFRSection 91.175(c), even in cases where the flight visibility
may be at the minimum derived by TBL 10 −1−1. These
factors include, but are not limited to:
1.Cockpit cutoff angle (the angle at which the cockpit or
other airframe structure limits downward visibility belowthe horizon).2.Combinations of high MDA/DH and low visibility
minimum, such as a conventional nonprecision approachwith a reduced helicopter visibility minima (per 14 CFRSection 97.3).
3.Type, configuration, and intensity of approach and
runway lighting systems.
4.Type of obscuring phenom enon and/or windshield
contamination.
AIM 10/12/17
10−1−5 Helicopter IFR Operations10−1−3. Helicopter Approach Procedures
to VFR Heliports
a.Helicopter approaches may be developed for
heliports that do not meet the design standards for an
IFR heliport. The majority of IFR approaches to VFR
heliports are developed in support of helicopteremergency medical services (HEMS) operators.
These approaches can be developed from conven-
tional NA V AIDs or a RNA V system (including GPS).
They are developed either as a Special Approach
(pilot training is required for special procedures due
to their unique characteristics) or a public approach
(no special training required). These instrument
procedures are developed as either an approachdesigned to a specific landing site, or an approach
designed to a point−in−space.
1. Approach to a specific landing site. The
approach is aligned to a missed approach point from
which a landing can be accomplished with a
maximum course change of 30 degrees. The visualsegment from the MAP to the landing site is evaluated
for obstacle hazards. These procedures are annotated:
“PROCEED VISUALLY FROM (NAMED MAP)OR CONDUCT THE SPECIFIED MISSED
APPROACH.”
(a)This phrase requires the pilot to either
acquire and maintain visual contact with the landing
site at or prior to the MAP, or execute a missedapproach. The visibility minimum is based on the
distance from the MAP to the landing site, among
other factors.
(b)The pilot is required to maintain the
published minimum visibility throughout the visual
segment.
(c)Similar to an approach to a runway, the
missed approach segment protection is not providedbetween the MAP and the landing site, and obstacle
or terrain avoidance from the MAP to the landing site
is the responsibility of the pilot.
(d)Upon reaching the MAP defined on the
approach procedure, or as soon as practicable after
reaching the MAP, the pilot advises ATC whetherproceeding visually and canceling IFR or complying
with the missed approach instructions. See para-
graph 5−1−15, Canceling IFR Flight Plan.(e)At least one of the following visual
references must be visible or identifiable before the
pilot may proceed visually:
(1)FATO or FATO lights.
(2)TLOF or TLOF lights.
(3)Heliport Instrument Lighting System
(HILS).
(4)Heliport Approach Lighting System
(HALS) or lead −in lights.
(5)Visual Glideslope Indicator (VGSI).
(6)Windsock or windsock light(s). See
note below.
(7)Heliport beacon. See note below.
(8)Other facilities or systems approved by
the Flight Technologies and Procedures Division
(AFS−400).
NOTE−
Windsock lights and heliport beacons should be locatedwithin 500 ft of the TLOF .
2. Approach to a Point −in−Space (PinS). At
locations where the MAP is located more than 2 SM
from the landing site, or the path from the MAP to the
landing site is populated with obstructions which
require avoidance actions or requires turns greater
than 30 degrees, a PinS procedure may be developed.
These approaches are annotated “PROCEED VFR
FROM (NAMED MAP) OR CONDUCT THE
SPECIFIED MISSED APPROACH.”
(a)These procedures require the pilot, at or
prior to the MAP, to determine if the published
minimum visibility, or the weather minimumsrequired by the operating rule, or operations
specifications (whichever is higher) is available to
safely transition from IFR to VFR flight. If not, thepilot must execute a missed approach. For Part 135
operations, pilots may not begin the instrument
approach unless the latest weather report indicatesthat the weather conditions are at or above the
authorized IFR minimums or the VFR weather
minimums (as required by the class of airspace,operating rule and/or Operations Specifications)
whichever is higher.
(b)Visual contact with the landing site is not
required; however, the pilot must maintain the
appropriate VFR weather minimums throughout the
visual segment. The visibility is limited to no lower
AIM 10/12/17
10−1−6 Helicopter IFR Operationsthan that published in the procedure, until canceling
IFR.
(c)IFR obstruction clearance areas are not
applied to the VFR segment between the MAP and
the landing site. Obstacle or terrain avoidance from
the MAP to the landing site is the responsibility of thepilot.
(d)Upon reaching the MAP defined on the
approach procedure, or as soon as practicable after
reaching the MAP, the pilot advises ATC whetherproceeding VFR and canceling IFR, or complying
with the missed approach instructions. See para-
graph 5−1−15, Canceling IFR Flight Plan.
(e)If the visual segment penetrates Class B,
C, or D airspace, pilots are responsible for obtaining
a Special VFR clearance, when required.
10−1−4. The Gulf of Mexico Grid System
a.On October 8, 1998, the Southwest Regional
Office of the FAA, with assistance from the
Helicopter Safety Advisory Conference (HSAC),implemented the world’s first Instrument Flight
Rules (IFR) Grid System in the Gulf of Mexico. This
navigational route structure is completely indepen-
dent of ground −based navigation aids (NA V AIDs)
and was designed to facilitate helicopter IFRoperations to offshore destinations. The Grid System
is defined by over 300 offshore waypoints located 20
minutes apart (latitude and longitude). Flight planroutes are routinely defined by just 4 segments:
departure point (lat/long), first en route grid
waypoint, last en route grid waypoint prior toapproach procedure, and destination point (lat/long).
There are over 4,000 possible offshore landing sites.
Upon reaching the waypoint prior to the destination,the pilot may execute an Of fshore Standard Approach
Procedure (OSAP), a Helicopter En Route Descent
Areas (HEDA) approach, or an Airborne RadarApproach (ARA). For more information on these
helicopter instrument procedures, refer to FAA AC
90−80B, Approval of Offshore Standard Approach
Procedures, Airborne Radar Approaches, and
Helicopter En Route Descent Areas, on the FAA
website http://www.faa.gov under Advisory Circu-
lars. The return flight plan is just the reverse with the
requested stand−alone GPS approach contained in the
remarks section.1.The large number (over 300) of waypoints in
the grid system makes it difficult to assign
phonetically pronounceable names to the waypoints
that would be meaningful to pilots and controllers. A
unique naming system was adopted that enablespilots and controllers to derive the fix position from
the name. The five −letter names are derived as
follows:
(a)The waypoints are divided into sets of
3 columns each. A three −letter identifier, identifying
a geographical area or a NA V AID to the north,
represents each set.
(b)Each column in a set is named after its
position, i.e., left (L), center (C), and right (R).
(c)The rows of the grid are named
alphabetically from north to south, starting with A for
the northern most row.
EXAMPLE −
LCHRC would be pronounced “Lake Charles RomeoCharlie.” The waypoint is in the right −hand column of the
Lake Charles VOR set, in row C (third south from the
northern most row).
2.In December 2009, significant improvements
to the Gulf of Mexico grid system were realized with
the introduction of ATC separation services usingADS−B. In cooperation with the oil and gas services
industry, HSAC and Helicopter Association Interna-
tional (HAI), the FAA installed an infrastructure ofADS−B ground stations, weather stations (AWOS)
and VHF remote communication outlets (RCO)
throughout a large area of the Gulf of Mexico. Thisinfrastructure allows the FAA’s Houston ARTCC to
provide “domestic −like” air traffic control service in
the offshore area beyond 12nm from the coastline tohundreds of miles offshore to aircraft equipped with
ADS−B. Properly equipped aircraft can now be
authorized to receive more direct routing, domesticen route separation minima and real time flight
following. Operators who do not have authorization
to receive ATC separation services using ADS −B,
will continue to use the low altitude grid system and
receive procedural separation from Houston AR TCC.
Non−ADS−B equipped aircraft also benefit from
improved VHF communication and expanded
weather information coverage.
3.Three requirements must be met for operators
to file IFR flight plans utilizing the grid:
AIM 10/12/17
10−1−7 Helicopter IFR Operations(a)The helicopter must be equipped for IFR
operations and equipped with IFR approved GPS
navigational units.
(b)The operator must obtain prior written
approval from the appropriate Flight Standards
District Office through a Letter of Authorization orOperations Specification, as appropriate.
(c)The operator must be a signatory to the
Houston ARTCC Letter of Agreement.
4.Operators who wish to benefit from ADS −B
based ATC separation services must meet thefollowing additional requirements:
(a)The Operator’s installed ADS −B Out
equipment must meet the performance requirements
of one of the following FAA Technical StandardOrders (TSO), or later revisions: TSO −C154c,
Universal Access Transceiver (UAT) Automatic
Dependent Surveillance −Broadcast (ADS −B) Equip-ment, or TSO −C166b, Extended Squitter Automatic
Dependent Surveillance −Broadcast (ADS −B) and
Traffic Information.
(b)Flight crews must comply with the
procedures prescribed in the Houston ARTCC Letter
of Agreement dated December 17, 2009, or later.
NOTE−
The unique ADS −B architecture in the Gulf of Mexico
depends upon r eception of an air craft’ s Mode C in addition
to the other message elements described in 14 CFR 91.227.Flight cr ews must be made aware that loss of Mode C also
means that ATC will not receive the aircraft’ s ADS −B
signal.
5.FAA/AIS publishes the grid system way-
points on the IFR Gulf of Mexico Vertical Flight
Reference Chart. A commercial equivalent is also
available. The chart is updated annually and isavailable from an FAA approved print
provider or FAA directly, website address:
http://www.faa.gov/air_traffic/flight_info/aeronav.
AIM 10/12/17
10−2−1 Special OperationsSection 2. Special Operations
10−2−1. Offshore Helicopter Operations
a. Introduction
The offshore environment offers unique applications
and challenges for helicopter pilots. The mission
demands, the nature of oil and gas exploration andproduction facilities, and the flight environment
(weather, terrain, obstacles, traffic), demand special
practices, techniques and procedures not found inother flight operations. Several industry
organizations have risen to the task of reducing
risks in offshore operations, including the Heli-
copter Safety Advisory Conference (HSAC)
(
http://www.hsac.org ), and the Offshore Committee
of the Helicopter Association International (HAI)
(http://www.rotor.com ). The following recommended
practices for of fshore helicopter operations are based
on guidance developed by HSAC for use in the Gulf
of Mexico, and provided here with their permission.
While not regulatory, these recommended practicesprovide aviation and oil and gas industry operators
with useful information in developing procedures to
avoid certain hazards of offshore helicopter opera-tions.
NOTE−
Like all aviation practices, these recommended practicesare under constant review. In addition to normalprocedures for comments, suggested changes, or correc-
tions to the AIM (contained in the Preface), any questions
or feedback concerning these recommended proceduresmay also be directed to the HSAC through the feedback
feature of the HSAC website (
http:// www.hsac.org ).
b. Passenger Management on and about
Heliport Facilities
1. Background. Several incidents involving
offshore helicopter passengers have highlighted the
potential for incidents and accidents on and about the
heliport area. The following practices will minimizerisks to passengers and others involved in heliport
operations.
2. Recommended Practices
(a)Heliport facilities should have a desig-
nated and posted passenger waiting area which is
clear of the heliport, heliport access points, and
stairways.(b)Arriving passengers and cargo should be
unloaded and cleared from the heliport and access
route prior to loading departing passengers and cargo.
(c)Where a flight crew consists of more than
one pilot, one crewmember should supervise the
unloading/loading process from outside the aircraft.
(d)Where practical, a designated facility
employee should assist with loading/unloading, etc.
c. Crane −Helicopter Operational Procedures
1. Background. Historical experience has
shown that catastrophic consequences can occurwhen industry safe practices for crane/helicopter
operations are not observed. The following recom-
mended practices are designed to minimize risks
during crane and helicopter operations.
2. Recommended Practices
(a) Personnel awareness
(1)Crane operators and pilots should
develop a mutual understanding and respect of the
others’ operational limitations and cooperate in thespirit of safety;
(2)Pilots need to be aware that crane
operators sometimes cannot release the load to cradle
the crane boom, such as when attached to wire linelubricators or supporting diving bells; and
(3)Crane operators need to be aware that
helicopters require warm up before takeoff, a
two−minute cool down before shutdown, and cannot
circle for extended lengths of time because of fuelconsumption.
(b)It is recommended that when helicopters
are approaching, maneuvering, taking off, or running
on the heliport, cranes be shutdown and the operatorleave the cab. Cranes not in use must have their
booms cradled, if feasible. If in use, the crane’s
boom(s) are to be pointed away from the heliport and
the crane shutdown for helicopter operations.
(c)Pilots will not approach, land on, takeoff,
or have rotor blades turning on heliports of structures
not complying with the above practice.
AIM 10/12/17
10−2−2 Special Operations(d)It is recommended that cranes on of fshore
platforms, rigs, vessels, or any other facility, which
could interfere with helicopter operations (including
approach/departure paths):
(1)Be equipped with a red rotating beacon
or red high intensity strobe light connected to the
system powering the crane, indicating the crane is
under power;
(2)Be designed to allow the operator a
maximum view of the helideck area and should be
equipped with wide −angle mirrors to eliminate blind
spots; and
(3)Have their boom tips, headache balls,
and hooks painted with high visibility international
orange.
d. Helicopter/Tanker Operations
1. Background. The interface of helicopters
and tankers during shipboard helicopter operations iscomplex and may be hazardous unless appropriate
procedures are coordinated among all parties. The
following recommended practices are designed tominimize risks during helicopter/tanker operations:
2. Recommended Practices
(a)Management, flight operations personnel,
and pilots should be familiar with and apply the
operating safety standards set forth in “Guide toHelicopter/Ship Operations”, International Chamber
of Shipping, Third Edition, 5 −89 (as amended),
establishing operational guidelines/standards andsafe practices sufficient to safeguard helicopter/tank-
er operations.
(b)Appropriate plans, approvals, and com-
munications must be accomplished prior to reaching
the vessel, allowing tanker crews sufficient time to
perform required safety preparations and positioncrew members to receive or dispatch a helicopter
safely.
(c)Appropriate approvals and direct commu-
nications with the bridge of the tanker must be
maintained throughout all helicopter/tanker opera-tions.
(d)Helicopter/tanker operations, including
landings/departures, must not be conducted until the
helicopter pilot −in−command has received and
acknowledged permission from the bridge of the
tanker.(e)Helicopter/tanker operations must not be
conducted during product/cargo transfer.
(f)Generally, permission will not be granted
to land on tankers during mooring operations or while
maneuvering alongside another tanker.
e. Helideck/Heliport Operational Hazard
Warning(s) Procedures
1. Background
(a)A number of operational hazards can
develop on or near offshore helidecks or onshoreheliports that can be minimized through procedures
for proper notification or visual warning to pilots.
Examples of hazards include but are not limited to:
(1)Perforating operations: subpara-
graph f.
(2)H
2S gas presence: subparagraph g.
(3)Gas venting: subparagraph h; or,
(4)Closed helidecks or heliports: sub −
paragraph i (unspecified cause).
(b)These and other operational hazards are
currently minimized through timely dissemination of
a written Notice to Airmen (NOTAM) for pilots by
helicopter companies and operators. A NOTAMprovides a written description of the hazard, time and
duration of occurrence, and other pertinent informa-
tion. ANY POTENTIAL HAZARD should becommunicated to helicopter operators or company
aviation departments as early as possible to allow the
NOTAM to be activated.
(c)To supplement the existing NOTAM
procedure and further assist in reducing these
hazards, a standardized visual signal(s) on thehelideck/heliport will provide a positive indication to
an approaching helicopter of the status of the landing
area. Recommended Practice(s) have been developed
to reinforce the NOTAM procedures and standardize
visual signals.
f. Drilling Rig Perforating Operations:
Helideck/Heliport Operational Hazard
Warning(s)/Procedure(s)
1. Background. A critical step in the oil well
completion process is perforation, which involves the
use of explosive charges in the drill pipe to open thepipe to oil or gas deposits. Explosive charges used in
conjunction with perforation operations offshore can
potentially be prematurely detonated by radio
AIM 10/12/17
10−2−3 Special Operationstransmissions, including those from helicopters. The
following practices are recommended.
2. Recommended Practices
(a) Personnel Conducting Perforating
Operations. Whenever perforating operations are
scheduled and operators are concerned that radio
transmissions from helicopters in the vicinity mayjeopardize the operation, personnel conducting
perforating operations should take the following
precautionary measures:
(1)Notify company aviation departments,
helicopter operators or bases, and nearby manned
platforms of the pending perforation operation so the
Notice to Airmen (NOTAM) system can be activated
for the perforation operation and the temporary
helideck closure.
(2)Close the deck and make the radio
warning clearly visible to passing pilots, install atemporary marking (described in subpara-
graph 10−2−1i1(b)) with the words “NO RADIO”
stenciled in red on the legs of the diagonals. Theletters should be 24 inches high and 12 inches wide.
(See FIG 10−2−1.)
(3)The marker should be installed during
the time that charges may be affected by radio
transmissions.
(b) Pilots
(1)Pilots when operating within 1,000 feet
of a known perforation operation or observing the
white X with red “NO RADIO” warning indicating
perforation operations are underway will avoid radio
transmissions from or near the helideck (within
1,000 feet) and will not land on the deck if the X is
present. In addition to communications radios, radiotransmissions are also emitted by aircraft radar,transponders, radar altimeters, and DME equipment,
and ELTs.
(2)Whenever possible, make radio calls to
the platform being approached or to the Flight
Following Communications Center at least one mile
out on approach. Ensure all communications arecomplete outside the 1,000 foot hazard distance. If no
response is received, or if the platform is not radio
equipped, further radio transmissions should not be
made until visual contact with the deck indicates it is
open for operation (no white “X”).
g. Hydrogen Sulfide Gas Helideck/Heliport
Operational Hazard Warning(s)/Procedures
1. Background. Hydrogen sulfide (H
2S) gas:
Hydrogen sulfide gas in higher concentrations(300−500 ppm) can cause loss of consciousness
within a few seconds and presents a hazard to pilots
on/near offshore helidecks. When operating in
offshore areas that have been identified to have
concentrations of hydrogen sulfide gas, the following
practices are recommended.
2. Recommended Practices
(a) Pilots
(1)Ensure approved protective air packs
are available for emergency use by the crew on the
helicopter.
(2)If shutdown on a helideck, request the
supervisor in charge provide a briefing on location of
protective equipment and safety procedures.
(3)If while flying near a helideck and the
visual red beacon alarm is observed or an unusually
strong odor of “rotten eggs” is detected, immediately
don the protective air pack, exit to an area upwind,and notify the suspected source field of the hazard.
FIG 10−2−1
Closed Helideck Marking − No Radio
AIM 10/12/17
10−2−4 Special Operations(b) Oil Field Supervisors
(1)If presence of hydrogen sulfide is
detected, a red rotating beacon or red high intensity
strobe light adjacent to the primary helideck stairwell
or wind indicator on the structure should be turned on
to provide visual warning of hazard. If the beacon is
to be located near the stairwell, the State of Louisiana“Offshore Heliport Design Guide” and FAA
Advisory Circular (AC) 150/5390 −2A, Heliport
Design Guide, should be reviewed to ensure properclearance on the helideck.
(2)Notify nearby helicopter operators and
bases of the hazard and advise when hazard is cleared.
(3)Provide a safety briefing to include
location of protective equipment to all arriving
personnel.
(4)Wind socks or indicator should be
clearly visible to provide upwind indication for the
pilot.
h. Gas Venting Helideck/Heliport Operational
Hazard Warning(s)/Procedures − Operations
Near Gas Vent Booms
1. Background. Ignited flare booms can re-
lease a large volume of natural gas and create a hot
fire and intense heat with little time for the pilot to
react. Likewise, unignited gas vents can releasereasonably large volumes of methane gas under
certain conditions. Thus, operations conducted very
near unignited gas vents require precautions to
prevent inadvertent ingestion of combustible gases
by the helicopter engine(s). The following practicesare recommended.
2. Pilots
(a)Gas will drift upwards and downwind of
the vent. Plan the approach and takeoff to observe and
avoid the area downwind of the vent
, remaining as far
away as practicable from the open end of the ventboom.
(b)Do not attempt to start or land on an
offshore helideck when the deck is downwind of a gas
vent unless properly trained personnel verify
conditions are safe.3. Oil Field Supervisors
(a)During venting of large amounts of
unignited raw gas, a red rotating beacon or red highintensity strobe light adjacent to the primary helideck
stairwell or wind indicator should be turned on to
provide visible warning of hazard. If the beacon is to
be located near the stairwell, the State of Louisiana
“Offshore Heliport Design Guide” and FAA
AC 150/5390 −2A, Heliport Design Guide, should be
reviewed to ensure proper clearance from the
helideck.
(b)Notify nearby helicopter operators and
bases of the hazard for planned operations.
(c)Wind socks or indicator should be clearly
visible to provide upward indication for the pilot.
i. Helideck/Heliport Operational Warn-
ing(s)/Procedure(s) − Closed Helidecks or
Heliports
1. Background. A white “X” marked diago-
nally from corner to corner across a helideck or
heliport touchdown area is the universally accepted
visual indicator that the landing area is closed forsafety of other reasons and that helicopter operations
are not permitted. The following practices are
recommended.
(a) Permanent Closing. If a helideck or
heliport is to be permanently closed, X diagonals of
the same size and location as indicated above should
be used, but the markings should be painted on thelanding area.
NOTE−
White Decks: If a helideck is painted white, then
international orange or yellow markings can be used for
the temporary or permanent diagonals.
(b) Temporary Closing. A temporary
marker can be used for hazards of an interim nature.This marker could be made from vinyl or other
durable material in the shape of a diagonal “X.” The
marker should be white with legs at least 20 feet long
and 3 feet in width. This marker is designed to be
quickly secured and removed from the deck using
grommets and rope ties. The duration, time, location,
and nature of these temporary closings should be
provided to and coordinated with company aviation
departments, nearby helicopter bases, and helicopter
operators supporting the area. These markers MUST
be removed when the hazard no longer exists.
(See FIG 10−2−2.)
AIM 10/12/17
10−2−5 Special OperationsFIG 10−2−2
Closed Helideck Marking
j. Offshore (VFR) Operating Altitudes for
Helicopters
1. Background. Mid−air collisions constitute
a significant percentage of total fatal offshorehelicopter accidents. A method of reducing this risk
is the use of coordinated VFR cruising altitudes. To
enhance safety through standardized vertical separa-tion of helicopters when flying in the offshore
environment, it is recommended that helicopter
operators flying in a particular area establish a
cooperatively developed Standard Operating Proce-
dure (SOP) for VFR operating altitudes. An example
of such an SOP is contained in this example.
2. Recommended Practice Example
(a) Field Operations. Without compromis-
ing minimum safe operating altitudes, helicopters
working within an offshore field “constituting a
cluster” should use altitudes not to exceed 500 feet.
(b) En Route Operations
(1)Helicopters operating below 750’ AGL
should avoid transitioning through offshore fields.
(2)Helicopters en route to and from
offshore locations, below 3,000 feet, weather
permitting, should use en route altitudes as outlinedin TBL 10 −2−1.
TBL 10−2−1
Magnetic Heading Altitude
0/C0095 to 179 /C0095 750’
1750’
2750’
180/C0095 359/C0095 1250’
2250’(c) Area Agreements. See HSAC Area
Agreement Maps for operating procedures for
onshore high density traffic locations.
NOTE−
Pilots of helicopters operating VFR above 3,000 feet above
the surface should refer to the current Federal Aviation
Regulations (14 CFR Part 91), and paragraph 3 −1−4,
Basic VFR Weather Minimums, of the AIM.
(d) Landing Lights. Aircraft landing lights
should be on to enhance aircraft identification:
(1)During takeoff and landings;
(2)In congested helicopter or fixed wing
traffic areas;
(3)During reduced visibility; or,
(4)Anytime safety could be enhanced.
k. Offshore Helidecks/Landing Communica-
tions
1. Background. To enhance safety, and pro-
vide appropriate time to prepare for helicopter
operations, the following is recommended whenanticipating a landing on an offshore helideck.
2. Recommended Practices
(a)Before landing on an offshore helideck,
pilots are encouraged to establish communications
with the company owning or operating the helideckif frequencies exist for that purpose.
(b)When impracticable, or if frequencies do
not exist, pilots or operations personnel should
attempt to contact the company owning or operating
the helideck by telephone. Contact should be madebefore the pilot departs home base/point of departure
to advise of intentions and obtain landing permission
if necessary.
AIM 10/12/17
10−2−6 Special OperationsNOTE−
It is recommended that communications be established aminimum of 10 minutes prior to planned arrival time. This
practice may be a requirement of some offshore
owner/operators.
NOTE−
1.See subparagraph 10 −2−1d for Tanker Operations.
2.Private use Heliport. Offshore heliports are privately
owned/operated facilities and their use is limited to
persons having prior authorization to utilize the facility.
l. Two (2) Helicopter Operations on Offshore
Helidecks
1. Background. Standardized procedures can
enhance the safety of operating a second helicopter
on an offshore helideck, enabling pilots to
determine/maintain minimum operational parame-ters. Orientation of the parked helicopter on the
helideck, wind and other factors may prohibit
multi−helicopter operations. More conservative
Rotor Diameter (RD) cl earances may be required
under dif fering condition, i.e., temperature, wet deck,
wind (velocity/direction/gusts), obstacles, approach/departure angles, etc. Operations are at the pilot’s
discretion.
2. Recommended Practice. Helideck size,
structural weight capability, and type of main rotor on
the parked and operating helicopter will aid indetermining accessibility by a second helicopter.
Pilots should determine that multi −helicopter deck
operations are permitted by the helideck owner/operator.
3. Recommended Criteria
(a) Minimum one −third rotor diameter
clearance (
1/3 RD). The landing helicopter main-
tains a minimum 1/3 RD clearance between the tips of
its turning rotor and the closest part of a parked and
secured helicopter (rotors stopped and tied down).
(b) Three foot parking distance from deck
edge (3’). Helicopters operating on an offshore
helideck land or park the helicopter with a skid/wheel
assembly no closer than 3 feet from helideck edge.
(c) Tiedowns. Main rotors on all helicopters
that are shut down be properly secured (tied down) to
prevent the rotor blades from turning.
(d)Medium (transport) and lar ger helicopters
should not land on any of fshore helideck where a lighthelicopter is parked unless the light helicopter is
property secured to the helideck and has main rotor
tied down.
(e)Helideck owners/operators should ensure
that the helideck has a serviceable anti −skid surface.
4. Weight and limitations markings on
helideck. The helideck weight limitations should be
displayed by markings visible to the pilot (see Stateof Louisiana “Offshore Heliport Design Guide” and
FAA AC 150/5390 −2A, Heliport Design Guide).
NOTE−
Some offshore helideck owners/operators have r estrictions
on the number of helicopters allowed on a helideck. When
helideck size permits, multiple (more than two) helicopter
operations are permitted by some operators.
m. Helicopter Rapid Refueling Procedures
(HRR)
1. Background. Helicopter Rapid Refueling
(HRR), engine(s)/rotors operating, can be conducted
safely when utilizing tr ained personnel and observing
safe practices. This recommended practice providesminimum guidance for HRR as outlined in National
Fire Protection Association (NFPA) and industry
practices. For detailed guidance, please refer toNational Fire Protection Association (NFPA) Docu-
ment 407, “Standard for Aircraft Fuel Servicing,”
1990 edition, including 1993 HRR Amendment.
NOTE−
Certain operators prohibit HRR, or “hot refueling,” or
may have specific procedures for certain aircraft orrefueling locations. See the General Operations Manualand/or Operations Specifications to determine theapplicable procedures or limitations.
2. Recommended Practices
(a)Only turbine −engine helicopters fueled
with JET A or JET A −1 with fueling ports located
below any engine exhausts may be fueled while anonboard engine(s) is (are) operating.
(b)Helicopter fueling while an onboard
engine(s) is (are) operating should only be conducted
under the following conditions:
(1)A properly certificated and current pilot
is at the controls and a trained refueler attending thefuel nozzle during the entire fuel servicing process.
The pilot monitors the fuel quantity and signals the
refueler when quantity is reached.
AIM 10/12/17
10−2−7 Special Operations(2)No electrical storms (thunderstorms)
are present within 10 nautical miles. Lightning can
travel great distances beyond the actual thunder-
storm.
(3)Passengers disembark the helicopter
and move to a safe location prior to HRR operations.When the pilot −in−command deems it necessary for
passenger safety that they remain onboard, passen-
gers should be briefed on the evacuation route tofollow to clear the area.
(4)Passengers not board or disembark
during HRR operations nor should cargo be loaded or
unloaded.
(5)Only designated personnel, trained in
HRR operations should conduct HRR written
authorization to include safe handling of the fuel and
equipment. (See your Company Operations/Safety
Manual for detailed instructions.)
(6)All doors, windows, and access points
allowing entry to the interior of the helicopter that are
adjacent to or in the immediate vicinity of the fuel
inlet ports kept closed during HRR operations.
(7)Pilots ensure that appropriate electrical/
electronic equipment is placed in standby −off
position, to preclude the possibility of electrical
discharge or other fire hazard, such as [i.e., weather
radar is on standby and no radio transmissions aremade (keying of the microphone/transmitter)].
Remember, in addition to communications radios,
radio transmissions are also emitted by aircraft radar,
transponders, radar altimeters, DME equipment, and
ELTs.
(8)Smoking be prohibited in and around
the helicopter during all HRR operations.
The HRR procedures are critical and present
associated hazards requiring attention to detail
regarding quality control, weather conditions, staticelectricity, bonding, and spill/fires potential.
Any activity associated with rotors turning
(i.e.; refueling embarking/disembarking, loading/
unloading baggage/freight; etc.) personnel shouldonly
approach the aircraft when authorized to do so.
Approach should be made via safe approach
path/walkway or “arc”− remain clear of all rotors.NOTE−
1.Marine vessels, barges etc.: Vessel motion presents
additional potential hazards to helicopter operations(blade flex, aircraft movement).
2.See
National Fire Protection Association (NFP A)
Document 407, “Standard for Aircraft Fuel Servic-ing”
for specifics r egarding non−HRR (r outine refueling
operations).
10−2−2. Helicopter Night VFR Operations
a. Effect of Lighting on Seeing Conditions in
Night VFR Helicopter Operations
NOTE−
This guidance was developed to support safe night VFRhelicopter emergency medical services (HEMS) opera-
tions. The principles of lighting and seeing conditions are
useful in any night VFR operation.
While ceiling and visibility significantly affect safety
in night VFR operations, lighting conditions alsohave a profound effect on safety. Even in conditions
in which visibility and ceiling are determined to be
visual meteorological conditions, the ability to
discern unlighted or low contrast objects and terrain
at night may be compromised. The ability to discernthese objects and terrain is the seeing condition, and
is related to the amount of natural and man made
lighting available, and the contrast, reflectivity, andtexture of surface terrain and obstruction features. In
order to conduct operations safely, seeing conditions
must be accounted for in the planning and executionof night VFR operations.
Night VFR seeing conditions can be described by
identifying “high lighting conditions” and “low
lighting conditions.”
1.High lighting conditions exist when one of
two sets of conditions are present:
(a)The sky cover is less than broken (less
than 5/8 cloud cover), the time is between the local
Moon rise and Moon set, and the lunar disk is at least
50% illuminated; or
(b)The aircraft is operated over surface
lighting which, at least, provides for the lighting of
prominent obstacles, the identification of terrain
features (shorelines, valleys, hills, mountains, slopes)
and a horizontal reference by which the pilot may
control the helicopter. For example, this surface
lighting may be the result of:
(1)Extensive cultural lighting (man −made,
such as a built −up area of a city),
AIM 10/12/17
10−2−8 Special Operations(2)Significant reflected cultural lighting
(such as the illumination caused by the reflection of
a major metropolitan area’s lighting reflecting off a
cloud ceiling), or
(3)Limited cultural lighting combined
with a high level of natural reflectivity of celestial
illumination, such as that provided by a surface
covered by snow or a desert surface.
2.Low lighting conditions are those that do not
meet the high lighting conditions requirements.
3.Some areas may be considered a high lighting
environment only in specific circumstances. For
example, some surfaces, such as a forest with limited
cultural lighting, normally have little reflectivity,requiring dependence on significant moonlight to
achieve a high lighting condition. However, when
that same forest is covered with snow, its reflectivitymay support a high lighting condition based only on
starlight. Similarly, a desolate area, with little cultural
lighting, such as a desert, may have such inherentnatural reflectivity that it may be considered a high
lighting conditions area regardless of season,
provided the cloud cover does not prevent starlightfrom being reflected from the surface. Other surfaces,
such as areas of open water, may never have enough
reflectivity or cultural lighting to ever be character-ized as a high lighting area.
4.Through the accumulation of night flying
experience in a particular area, the operator willdevelop the ability to determine, prior to departure,
which areas can be considered supporting high or low
lighting conditions. Without that operational experi-ence, low lighting considerations should be applied
by operators for both pre −flight planning and
operations until high lighting conditions are observed
or determined to be regularly available.
b. Astronomical Definitions and Background
Information for Night Operations
1. Definitions
(a)Horizon. Wherever one is located on or
near the Earth’s surface, the Earth is perceived asessentially flat and, therefore, as a plane. If there are
no visual obstructions, the apparent intersection of
the sky with the Earth’s (plane) surface is the horizon,which appears as a circle centered at the observer. For
rise/set computations, the observer’s eye is consid-
ered to be on the surface of the Earth, so that thehorizon is geometrically exactly 90 degrees from the
local vertical direction.
(b)Rise, Set. During the course of a day the
Earth rotates once on its axis causing the phenomena
of rising and setting. All celestial bodies, the Sun,
Moon, stars and planets, seem to appear in the sky at
the horizon to the East of any particular place, then to
cross the sky and again disappear at the horizon to the
West. Because the Sun and Moon appear as circular
disks and not as points of light, a definition of rise or
set must be very specific, because not all of eitherbody is seen to rise or set at once.
(c)Sunrise and sunset refer to the times when
the upper edge of the disk of the Sun is on the horizon,considered unobstructed relative to the location of
interest. Atmospheric conditions are assumed to be
average, and the location is in a level region on theEarth’s surface.
(d)Moonrise and moonset times are com-
puted for exactly the same circumstances as forsunrise and sunset. However, moonrise and moonset
may occur at any time during a 24 hour period and,
consequently, it is often possible for the Moon to beseen during daylight, and to have moonless nights. It
is also possible that a moonrise or moonset does not
occur relative to a specific place on a given date.
(e)Transit. The transit time of a celestial
body refers to the instant that its center crosses an
imaginary line in the sky − the observer’s meridian −
running from north to south.
(f)Twilight. Before sunrise and again after
sunset there are intervals of time, known as“twilight,” during which there is natural light
provided by the upper atmosphere, which does
receive direct sunlight and reflects part of it towardthe Earth’s surface.
(g)Civil twilight is defined to begin in the
morning, and to end in the evening when the center of
the Sun is geometrically 6 degrees below the horizon.
This is the limit at which twilight illumination is
sufficient, under good weather conditions, forterrestrial objects to be clearly distinguished.
2.Title 14 of the Code of Federal Regulations
applies these concepts and definitions in addressingthe definition of night (Section 1.1), the requirement
for aircraft lighting (Section 91.209) and pilot
recency of night experience (Section 61.67).
AIM 10/12/17
10−2−9 Special Operationsc. Information on Moon Phases and Changes in
the Percentage of the Moon Illuminated
From any location on the Earth, the Moon appears to
be a circular disk which, at any specific time, is
illuminated to some degree by direct sunlight. During
each lunar orbit (a lunar month), we see the Moon’sappearance change from not visibly illuminated
through partially illuminated to fully illuminated,then back through partially illuminated to not
illuminated again. There are eight distinct, tradition-
ally recognized stages, called phases. The phases
designate both the degree to which the Moon is
illuminated and the geometric appearance of theilluminated part. These phases of the Moon, in the
sequence of their occurrence (starting from New
Moon), are listed in FIG 10−2−3.
FIG 10−2−3
Phases of the Moon
New Moon − The Moon’s unilluminated side is facing the Earth. The Moon is not visible
(except during a solar eclipse).
Waxing Crescent − The Moon appears to be partly but less than one −half illuminated by
direct sunlight. The fraction of the Moon’s disk that is illuminated is increasing.
First Quarter − One−half of the Moon appears to be illuminated by direct sunlight. The
fraction of the Moon’s disk that is illuminated is increasing.
Waxing Gibbous − The Moon appears to be more than one −half but not fully illuminated by
direct sunlight. The fraction of the Moon’s disk that is illuminated is increasing.
Full Moon − The Moon’s illuminated side is facing the Earth. The Moon appears to be
completely illuminated by direct sunlight.
Waning Gibbous − The Moon appears to be more than one −half but not fully
illuminated by direct sunlight. The fraction of the Moon’s disk that is illuminated is
decreasing.
Last Quarter − One−half of the Moon appears to be illuminated by direct sunlight. The
fraction of the Moon’s disk that is illuminated is decreasing.
Waning Crescent − The Moon appears to be partly but less than one −half illuminated by
direct sunlight. The fraction of the Moon’s disk that is illuminated is decreasing.
AIM 10/12/17
10−2−10 Special Operations1.The percent of the Moon’s surface illumi-
nated is a more refined, quantitative description of the
Moon’s appearance than is the phase. Considering the
Moon as a circular disk, at New Moon the percent
illuminated is 0; at First and Last Quarters it is 50%;
and at Full Moon it is 100%. During the crescent
phases the percent illuminated is between 0 and 50%
and during gibbous phases it is between 50% and100%.
2.For practical purposes, phases of the Moon
and the percent of the Moon illuminated are
independent of the location on the Earth from wherethe Moon is observed. That is, all the phases occur at
the same time regardless of the observer’s position.
3.For more detailed information, refer to the
United States Naval Observatory site referencedbelow.
d. Access to Astronomical Data for Determina-
tion of Moon Rise, Moon Set, and Percentage ofLunar Disk Illuminated
1.Astronomical data for the determination of
Moon rise and set and Moon phase may be obtained
from the United States Naval Observatory using aninteractive query available at:
http://aa.usno.navy.mil/
2.Click on “Data Services,” and then on
“Complete Sun and Moon Data for One Day.”
3.You can obtain the times of sunrise, sunset,
moonrise, moonset, transits of the Sun and Moon, and
the beginning and end of civil twilight, along with
information on the Moon’s phase by specifying thedate and location in one of the two forms on this web
page and clicking on the “Get data” button at the end
of the form. Form “A” is used for cities or towns in the
U.S. or its territories. Form “B” for all other locations.
An example of the data available from this site isshown in TBL 10 −2−2.
4.Additionally, a yearly table may be
constructed for a particular location by using the
“Table of Sunrise/Sunset, Moonrise/Moonset, orTwilight Times for an Entire Year” selection.TBL 10−2−2
Sample of Astronomical Data Available
from the Naval Observatory
The following information is provided for
New Orleans, Orleans Parish, Louisiana
(longitude W90.1, latitude N30.0)
Tuesday
29 May 2007Central Daylight Time
SUN
Begin civil twilight 5:34 a.m.
Sunrise 6:01 a.m.
Sun transit 12:58 p.m.
Sunset 7:55 p.m.
End civil twilight 8:22 p.m.
MOON
Moonrise 5:10 p.m. on preceding day
Moonset 4:07 a.m.
Moonrise 6:06 p.m.
Moon transit 11:26 p.m.
Moonset 4:41 a.m. on following day
Phase of the Moon on 29 May: waxing gibbous with
95% of the Moon’s visible disk illuminated.
Full Moon on 31 May 2007 at 8:04 p.m. Central
Daylight Time.
10−2−3. Landing Zone Safety
a.This information is provided for use by
helicopter emergency medical services (HEMS)
pilots, program managers, medical personnel, law
enforcement, fire, and rescue personnel to furthertheir understanding of the safety issues concerning
Landing Zones (LZs). It is recommended that HEMS
operators establish working relationships with theground responder organizations they may come in
contact with in their flight operations and share this
information in order to establish a common frame of
reference for LZ selection, operations, and safety.
AIM 10/12/17
10−2−11 Special Operationsb.The information provided is largely based on
the booklet, LZ − Preparing the Landing Zone, issued
by National Emergency Medical Services Pilots
Association (NEMSPA), and the guidance developed
by the University of Tennessee Medical Center’sLIFESTAR program, and is used with their
permission. For additional information, go to
http://www.nemspa.org/ .
c.Information concerning the estimation of wind
velocity is based on the Beaufort Scale. See
http://www.spc.noaa.gov/faq/tornado/beaufort.html
for more information.
d. Selecting a Scene LZ
1.If the situation requires the use of a helicopter,
first check to see if there is an area large enough to
land a helicopter safely.
FIG 10−2−4
Recommended Minimum Landing Zone Dimensions
2.For the purposes of FIG 10−2−4 the follow-
ing are provided as examples of relative helicoptersize:(a)Small Helicopter: Bell 206/407, Euro-
copter AS −350/355, BO −105, BK−117.
(b)Medium Helicopter: Bell UH −1 (Huey)
and derivatives (Bell 212/412), Bell 222/230/430Sikorsky S −76, Eurocopter SA −365.
(c)Large Helicopter: Boeing Chinook,
Eurocopter Puma, Sikorsky H −60 series
(Blackhawk), SK −92.
3.The LZ should be level, firm and free of loose
debris that could possibly blow up into the rotor
system.
4.The LZ should be clear of people, vehicles
and obstructions such as trees, poles and wires.Remember that wires are dif ficult to see from the air.
The LZ must also be free of stumps, brush, post and
large rocks. See FIG 10−2−5.
FIG 10−2−5
Landing Zone Hazards
5.Keep spectators back at least 200 feet. Keep
emergency vehicles 100 feet away and have fireequipment (if available) standing by. Ground
personnel should wear eye protection, if available,
during landing and takeoff operations. To avoid loose
objects being blown around in the LZ, hats should be
removed; if helmets are worn, chin straps must be
securely fastened.
6.Fire fighters (if available) should wet down
the LZ if it is extremely dusty.
AIM 10/12/17
10−2−12 Special Operationse. Helping the Flightcrew Locate the Scene
1.If the LZ coordinator has access to a GPS unit,
the exact latitude and longitude of the LZ should berelayed to the HEMS pilot. If unable to contact the
pilot directly, relay the information to the HEMS
ground communications specialist for relaying to the
pilot, so that they may locate your scene more
efficiently. Recognize that the aircraft may approach
from a direction different than the direct path from the
takeoff point to the scene, as the pilot may have to
detour around terrain, obstructions or weather
en route.
2.Especially in daylight hours, mountainous
and densely populated areas can make sighting a
scene from the air difficult. Often, the LZ coordinator
on the ground will be asked if she or he can see or hear
the helicopter.
3.Flightcrews use a clock reference method for
directing one another’s attention to a certain direction
from the aircraft. The nose of the aircraft is always
12 o’clock, the right side is 3 o’clock, etc. When the
LZ coordinator sees the aircraft, he/she should use
this method to assist the flightcrew by indicating the
scene’s clock reference position from the nose of the
aircraft. For example, “Accident scene is located at
your 2 o’clock position.” See FIG 10−2−6.
FIG 10−2−6
“Clock” System for Identifying Positions
Relative to the Nose of the Aircraft
4.When the helicopter approaches the scene, it
will normally orbit at least one time as the flight crew
observes the wind direction and obstacles that could
interfere with the landing. This is often referred to as
the “high reconnaissance” maneuver.
f. Wind Direction and Touchdown Area
1.Determine from which direction the wind is
blowing. Helicopters normally land and takeoff intothe wind.
2.If contact can be established with the pilot,
either directly or indirectly through the HEMS
ground communications specialist, describe the wind
in terms of the direction the wind is from and the
speed.
3.Common natural sources of wind direction
information are smoke, dust, vegetation movement,water streaks and waves. Flags, pennants, streamers
can also be used. When describing the direction, use
the compass direction from which the wind isblowing (example: from the North −West).
4.Wind speed can be measured by small
hand−held measurement devices, or an observer’s
estimate can be used to provide velocity information.
The wind value should be reported in knots (nautical
miles per hour). If unable to numerically measure
wind speed, use TBL 10 −2−3 to estimate velocity.
Also, report if the wind conditions are gusty, or if the
wind direction or velocity is variable or has changedrecently.
5.If any obstacle(s) exist, ensure their descrip-
tion, position and approximate height are
communicated to the pilot on the initial radio call.
AIM 10/12/17
10−2−13 Special OperationsTBL 10−2−3
Table of Common References for Estimating Wind Velocity
Wind
(Knots)Wind
ClassificationAppearance of Wind Effects
On the Water On Land
Less than 1 Calm Sea surface smooth and mirror −like Calm, smoke rises vertically
1−3 Light Air Scaly ripples, no foam crests Smoke drift indicates wind direction,
wind vanes are still
4−6 Light Breeze Small wavelets, crests glassy, no
breakingWind felt on face, leaves rustle, vanesbegin to move
7−10 Gentle Breeze Large wavelets, crests begin to break,
scattered whitecapsLeaves and small twigs constantlymoving, light flags extended
11−16 Moderate Breeze Small waves 1 −4 ft. becoming longer,
numerous whitecapsDust, leaves, and loose paper lifted,small tree branches move
17−21 Fresh Breeze Moderate waves 4 −8 ft. taking longer
form, many whitecaps, some spraySmall trees in leaf begin to sway
22−27 Strong Breeze Larger waves 8 −13 ft., whitecaps
common, more sprayLarger tree branches moving, whistlingin wires
28−33 Near Gale Sea heaps up, waves 13 −20 ft., white
foam streaks off breakersWhole trees moving, resistance feltwalking against wind
34−40 Gale Moderately high (13 −20 ft.) waves of
greater length, edges of crests begin to
break into spindrift, foam blown in
streaksWhole trees in motion, resistance feltwalking against wind
41−47 Strong Gale High waves (20 ft.), sea begins to roll,
dense streaks of foam, spray may reduce
visibilitySlight structural damage occurs, slate
blows off roofs
48−55 Storm Very high waves (20 −30 ft.) with
overhanging crests, sea white with
densely blown foam, heavy rolling,
lowered visibilitySeldom experienced on land, treesbroken or uprooted, “considerable
structural damage”
56−63 Violent Storm Exceptionally high (30 −45 ft.) waves,
foam patches cover sea, visibility more
reduced
64+ Hurricane Air filled with foam, waves over 45 ft.,
sea completely white with driving spray,
visibility greatly reduced
EXAMPLE −
Wind from the South −East, estimated speed 15 knots. Wind shifted from North −East about fifteen minutes ago, and is gusty.
AIM 10/12/17
10−2−14 Special Operationsg. Night LZs
1.There are several ways to light a night LZ:
(a)Mark the touchdown area with five lights
or road flares, one in each corner and one indicatingthe direction of the wind. See FIG 10−2−7.
FIG 10−2−7
Recommended Lighting for
Landing Zone Operations at Night
NOTE−
Road flares are an intense source of ignition and may be
unsuitable or dangerous in certain conditions. In any case,
they must be closely managed and firefighting equipmentshould be present when used. Other light sources arepreferred, if available.
(b)If chemical light sticks may be used, care
should be taken to assure they are adequately secured
against being dislodged by the helicopter’s rotor
wash.
(c)Another method of marking a LZ uses four
emergency vehicles with their low beam headlights
aimed toward the intended landing area.
(d)A third method for marking a LZ uses two
vehicles. Have the vehicles direct their headlight
beams into the wind, crossing at the center of the LZ.
(If fire/rescue personnel are available, the reflectivestripes on their bunker gear will assist the pilot
greatly.)
2.At night, spotlights, flood lights and hand
lights used to define the LZ are not to be pointed at the
helicopter. However, they are helpful when pointed
toward utility poles, trees or other hazards to the
landing aircraft. White lights such as spotlights,flashbulbs and hi −beam headlights ruin the pilot’s
night vision and temporarily blind him. Red lights,
however, are very helpful in finding accidentlocations and do not affect the pilot’s night vision as
significantly.
3.As in Day LZ operations, ensure radio contact
is accomplished between ground and air, if possible.
h. Ground Guide
1.When the helicopter is in sight, one person
should assist the LZ Coordinator by guiding the
helicopter into a safe landing area. In selecting an LZ
Coordinator, recognize that medical personnelusually are very busy with the patient at this time. It
is recommended that the LZ Coordinator be someone
other than a medical responder, if possible. Eyeprotection should be worn. The ground guide should
stand with his/her back to the wind and his/her arms
raised over his/her head (flashlights in each hand fornight operations.)
2.The pilot will confirm the LZ sighting by
radio. If possible, once the pilot has identified the LZ,
the ground guide should move out of the LZ.
3.As the helicopter turns into the wind and
begins a descent, the LZ coordinator should provideassistance by means of radio contact, or utilize the
“unsafe signal” to wave off the helicopter if the LZ is
not safe (see FIG 10 −2−8). The LZ Coordinator
should be far enough from the touchdown area that
he/she can still maintain visual contact with the pilot.
i. Assisting the Crew
1.After the helicopter has landed, do not
approach the helicopter. The crew will approach you.
2.Be prepared to assist the crew by providing
security for the helicopter. If asked to provide
security, allow no one but the crew to approach the
aircraft.
3.Once the patient is prepared and ready to load,
allow the crew to open the doors to the helicopter and
guide the loading of the patient.
4.When approaching or departing the helicop-
ter, always be aware of the tail rotor and always
follow the directions of the crew. Working around arunning helicopter can be potentially dangerous. The
environment is very noisy and, with exhaust gases
and rotor wash, often windy. In scene operations, thesurface may be uneven, soft, or slippery which can
lead to tripping. Be very careful of your footing in this
environment.
AIM 10/12/17
10−2−15 Special Operations5.The tail rotor poses a special threat to
working around a running helicopter. The tail rotor
turns many times faster than the main rotor, and is
often invisible even at idle engine power. Avoid
walking towards the tail of a helicopter beyond theend of the cabin, unless specifically directed by the
crew.
NOTE−
Helicopters typically have doors on the sides of the cabin,
but many use aft mounted “clamshell” type doors forloading and unloading patients on litters or stretchers.
When using these doors, it is important to avoid moving any
further aft than necessary to operate the doors andload/unload the patient. Again, always comply with thecrew’ s instructions.
j. General Rules
1.When working around helicopters, always
approach and depart from the front, never from therear. Approaching from the rear can increase your risk
of being struck by the tail rotor, which, when at
operating engine speed, is nearly invisible.
2.To prevent injury or damage from the main
rotor, never raise anything over your head.
3.If the helicopter landed on a slope, approach
and depart from the down slope side only.
4.When the helicopter is loaded and ready for
take off, keep the departure path free of vehicles andspectators. In an emergency, this area is needed to
execute a landing.
k. Hazardous Chemicals and Gases
1.Responding to accidents involving hazardous
materials requires special handling by fire/rescueunits on the ground. Equally important are the
preparations and considerations for helicopter
operations in these areas.
2.Hazardous materials of concern are those
which are toxic, poisonous, flammable, explosive,
irritating, or radioactive in nature. Helicopter
ambulance crews normally don’t carry protectivesuits or breathing apparatuses to protect them from
hazardous materials.
3.The helicopter ambulance crew must be told
of hazardous materials on the scene in order to avoidthe contamination of the crew. Patients/victims
contaminated by hazardous materials may require
special precautions in packaging before loading on
the aircraft for the medical crew’s protection, or may
be transported by other means.
4.Hazardous chemicals and gases may be fatal
to the unprotected person if inhaled or absorbed
through the skin.
5.Upon initial radio contact, the helicopter crew
must be made aware of any hazardous gases in the
area. Never assume that the crew has already been
informed. If the aircraft were to fly through thehazardous gases, the crew could be poisoned and/or
the engines could develop mechanical problems.
6.Poisonous or irritating gases may cling to a
victim’s clothing and go unnoticed until the patient is
loaded and the doors of the helicopter are closed. To
avoid possible compromise of the crew, all of these
patients must be decontaminated prior to loading.
l. Hand Signals
1.If unable to make radio contact with the
HEMS pilot, use the following signals:
FIG 10−2−8
Recommended Landing Zone Ground Signals
AIM 10/12/17
10−2−16 Special Operationsm. Emergency Situations
1.In the event of a helicopter accident in the
vicinity of the LZ, consider the following:
(a) Emergency Exits:
(1)Doors and emergency exits are typical-
ly prominently marked. If possible, operators should
familiarize ground responders with the door system
on their helicopter in preparation for an emergencyevent.
(2)In the event of an accident during the LZ
operation, be cautious of hazards such as sharp and
jagged metal, plastic windows, glass, any rotatingcomponents, such as the rotors, and fire sources, such
as the fuel tank(s) and the engine.
(b) Fire Suppression:
Helicopters used in HEMS operations are usually
powered by turboshaft engines, which use jet fuel.
Civil HEMS aircraft typically carry between 50 and
250 gallons of fuel, depending upon the size of the
helicopter, and planned flight duration, and the fuel
remaining after flying to the scene. Use water tocontrol heat and use foam over fuel to keep vapors
from ignition sources.
10−2−4. Emergency Medical Service (EMS)
Multiple Helicopter Operations
a. Background. EMS helicopter operators often
overlap other EMS operator areas. Standardized
procedures can enhance the safety of operatingmultiple helicopters to landing zones (LZs) and to
hospital heliports. Communication is the key to
successful operations and in maintaining organiza-tion between helicopters, ground units and
communication centers. EMS helicopter operators
which operate in the same areas should establish joint
operating procedures and provide them to related
agencies.
b. Recommended Procedures.
1. Landing Zone Operations. The first heli-
copter to arrive on −scene should establish
communications with the ground unit at least 10 NMs
from the LZ to receive a LZ briefing and to provide
ground control the number of helicopters that can be
expected. An attempt should be made to contact other
helicopters on 123.025 to pass on to them pertinent
LZ information and the ground unit’s frequency.
Subsequent helicopters arriving on scene shouldestablish communications on 123.025 at least 10
NMs from the LZ. After establishing contact on
123.025, they should contact the ground unit for
additional information. All helicopters should
monitor 123.025 at all times.
(a)If the landing zone is not established by
the ground unit when the first helicopter arrives,
then the first helicopter should establish altitudeand orbit location requirements for the other
arriving helicopters. Recommended altitude separa-
tion between helicopters is 500 feet (weather and
airspace permitting). Helicopters can orbit on
cardinal headings from the scene coordinates. (See
FIG 10−2−9.)
(b)Upon landing in the LZ, the first
helicopter should update the other helicopters on the
LZ conditions, i.e., space, hazards and terrain.
(c)Before initiating any helicopter move-
ment to leave the LZ, all operators should attempt to
contact other helicopters on 123.025, and state theirposition and route of flight intentions for departing
the LZ.
2. Hospital Operations. Because many
hospitals require landing permission and have
established procedures (frequencies to monitor,
primary and secondary routes for approaches anddepartures, and orbiting areas if the heliport is
occupied) pilots should always receive a briefing
from the appropriate facility (communication center,flight following, etc.) before proceeding to the
hospital.
(a)In the event of multiple helicopters
coming into the hospital heliport, the helicopter
nearest to the heliport should contact other inbound
helicopters on 123.025 and establish intentions.Follow the guidelines established in the LZ
operations.
(b)To facilitate approach times, the pilot
−in−
command of the helicopter occupying the hospital
heliport should advise any other operators whether
the patient will be off loaded with the rotor bladesturning or stopped, and the approximate time to do so.
(c)Before making any helicopter movement
to leave the hospital heliport, all operators shouldattempt to contact other helicopters on 123.025 and
state their position and route of flight intentions for
departing the heliport.
AIM 10/12/17
10−2−17 Special OperationsFIG 10−2−9
EMS Multiple Helicopter LZ/Heliport Operation
NOTE−
If the LZ/hospital heliport weather conditions or airs pace altitude restrictions prohibit the recommended vertical
separation, 1 NM separations should be kept between helicopter orbit areas.
AIM 10/12/17
Appendix 1 −1 Bird/Other Wildlife Strike ReportAppendix 1. Bird/Other Wildlife Strike Report
AIM 10/12/17
Appendix 1 −2 Bird/Other Wildlife Strike Report
FOLD AND TAPE HERE
AIM 10/12/17
Appendix 2 −1 V olcanic Activity Reporting Form (V AR)Appendix 2. Volcanic Activity Reporting Form (VAR)
E−mail address: GVN@volcano.si.edu
AIM 10/12/17
Appendix 3 −1 Abbreviations/AcronymsAppendix 3. Abbreviations/Acronyms
As used in this manual, the following abbreviations/
acronyms have the meanings indicated.
Abbreviation/
AcronymMeaning
A A W U ..... Alaskan Aviation Weather Unit
A A S ....... Airport Advisory Service
A C ........ Advisory Circular
ACAR ..... Aircraft Communications Addressing and
Reporting System
ADCUS .... Advise Customs
ADDS ...... Aviation Digital Data Service
A D F ....... Automatic Direction Finder
ADIZ ...... Air Defense Identification Zone
ADS−B..... Automatic Dependent
Surveillance −Broadcast
A F B ....... Air Force Base
AFCS ...... Automatic Flight Control System
AFIS ....... Automatic Flight Information Service
A F M....... Aircraft Flight Manual
A G L ....... Above Ground Level
AHRS ...... Attitude Heading Reference System
A I M ....... Aeronautical Information Manual
AIRMET . . . Airmen’s Meteorological Information
A I S ........ Aeronautical Information Services
A L D ....... Available Landing Distance
ALDARS . . . Automated Lightning Detection and
Reporting System
A L S ....... Approach Light Systems
AMSL ..... Above Mean Sea Level
A N P ....... Actual Navigation Performance
AOCC ..... Airline Operations Control Center
A P ........ Autopilot System
A P V ....... Approach with Vertical Guidance
A R ........ Authorization Required
ARENA .... Areas Noted for Attention
ARFF IC .... Aircraft Rescue and Fire Fighting Incident
Commander
ARINC ..... Aeronautical Radio Incorporated
A R O ....... Airport Reservations Office
ARSA ...... Airport Radar Service Area
ARSR ...... Air Route Surveillance Radar
A R T C C..... Air Route Traffic Control Center
A R T S ...... Automated Radar Terminal System
ASDE−X ... Airport Surface Detection Equipment −
Model X
ASOS ...... Automated Surface Observing System
A S R ....... Airport Surveillance RadarAbbreviation/
AcronymMeaning
ASRS ...... Aviation Safety Reporting System
ASSC Airport Surface Surveillance Capability
A T C ....... Air Traffic Control
ATCRBS .... Air Traffic Control Radar Beacon System
ATCSCC .... Air Traffic Control System Command
Center
A T C T ...... Airport Traffic Control Tower
A T D ....... Along−Track Distance
A T I S ....... Automatic Terminal Information Service
A T T ....... Attitude Retention System
A W C....... Aviation Weather Center
A W O S ..... Automated Weather Observing System
A W S S...... Automated Weather Sensor System
A W T T ..... Aviation Weather Technology Transfer
A W W ...... Severe Weather Forecast Alert
BAASS ..... Bigelow Aerospace Advanced Space
Studies
B B S ....... Bulletin Board System
B C ........ Back Course
BECMG .... Becoming group
C / A........ Coarse Acquisition
C A R T S..... Common Automated Radar Terminal
System (ARTS) (to include ARTS IIIE and
ARTS IIE)
C A T ....... Clear Air Turbulence
C D ........ Controller Display
C D I........ Course Deviation Indicator
C D R ....... Coded Departure Route
CERAP ..... Combined Center/RAPCON
C F A ....... Controlled Firing Area
CFIT ....... Controlled Flight into Terrain
C F R ....... Code of Federal Regulations
C O A ....... Certificate of Waiver or Authorization
CPDLC ..... Controller Pilot Data Link
Communications
C T A F ...... Common Traffic Advisory Frequency
CVFP ...... Charted Visual Flight Procedure
CVRS ...... Computerized V oice Reservation System
C W A....... Center Weather Advisory
CWSU ..... Center Weather Service Unit
D A ........ Decision Altitude
D C A ....... Ronald Reagan Washington National
Airport
D C P ....... Data Collection Package
D E R ....... Departure End of Runway
AIM 10/12/17
Appendix 3 −2 Abbreviations/AcronymsAbbreviation/
AcronymMeaning
D H ........ Decision Height
D M E....... Distance Measuring Equipment
DME/N ..... Standard DME
DME/P ..... Precision DME
D O D....... Department of Defense
D P ........ Instrument Departure Procedure
D P U ....... Data Processor Unit
D R T ....... Diversion Recovery Tool
D R V S M .... Domestic Reduced Vertical Separation
Minimum
D U A T S..... Direct User Access Terminal System
D V A ....... Diverse Vector Area
DVFR ...... Defense Visual Flight Rules
DVRSN .... Diversion
EDCT ...... Expect Departure Clearance Time
E F A S ...... En Route Flight Advisory Service
E F V ....... Enhanced Flight Visibility
EFVS ...... Enhanced Flight Vision System
E L T........ Emergency Locator Transmitter
EMAS ..... Engineered Materials Arresting System
E P E ....... Estimate of Position Error
E S V ....... Expanded Service V olume
E T A ....... Estimated Time of Arrival
E T D ....... Estimated Time of Departure
E T E ....... Estimated Time En Route
EWINS ..... Enhanced Weather Information System
E W R....... Newark International Airport
F A......... Area Forecast
F A A ....... Federal Aviation Administration
F A F........ Final Approach Fix
FAROS ..... Final Approach Runway Occupancy Signal
F A W P ...... Final Approach Waypoint
F B......... Fly−by
F C C ....... Federal Communications Commission
F D ........ Flight Director System
F D C ....... Flight Data Center
F D E ....... Fault Detection and Exclusion
F I R ........ Flight Information Region
F I S ........ Flight Information Service
FISDL ..... Flight Information Services Data Link
FLIP ....... Flight Information Publication
F M S ....... Flight Management System
F O ........ Fly−over
F P A........ Flight Path Angle
F P V ....... Flight Path Vector
FPNM ...... Feet Per Nautical Mile
FSDO ...... Flight Standards District OfficeAbbreviation/
AcronymMeaning
F S S........ Flight Service Station
GBAS ...... Ground Based Augmentation System
G E O ....... Geostationary Satellite
G L S ....... GBAS Landing System
GNSS ...... Global Navigation Satellite System
GNSSP ..... Global Navigation Satellite System Panel
G P S ....... Global Positioning System
G R I........ Group Repetition Interval
G S D ....... Geographical Situation Display
G U S ....... Ground Uplink Station
H A T ....... Height Above Touchdown
H D T A...... High Density Traffic Airports
HEMS ..... Helicopter Emergency Medical Services
HIRL ...... High Intensity Runway Lights
H I W A S..... Hazardous Inflight Weather Advisory
Service
H R R ....... Helicopter Rapid Refueling Procedures
H U D....... Head−Up Display
H z......... Hertz
I A F ........ Initial Approach Fix
I A P ........ Instrument Approach Procedure
I A S ........ Indicated Air Speed
I A W P ...... Initial Approach Waypoint
ICAO ...... International Civil Aviation Organization
I F ......... Intermediate Fix
IFIM ....... International Flight Information Manual
I F R ........ Instrument Flight Rules
I L S ........ Instrument Landing System
ILS/PRM . . . Instrument Landing System/Precision
Runway Monitor
I M......... Inner Marker
I M C ....... Instrument Meteorological Conditions
InFO ....... Information For Operators
I N S ........ Inertial Navigation System
I O C........ Initial Operational Capability
I R ......... IFR Military Training Route
I R U........ Inertial Reference Unit
ITWS ...... Integrated Terminal Weather System
J F K........ John F. Kennedy International Airport
k H z........ Kilohertz
L A A ....... Local Airport Advisory
LAAS ...... Local Area Augmentation System
LAHSO .... Land and Hold Short Operations
L A W R S .... Limited Aviation Weather Reporting
Station
L D A ....... Localizer Type Directional Aid
AIM 10/12/17
Appendix 3 −3 Abbreviations/AcronymsAbbreviation/
AcronymMeaning
LDA/PRM . . Localizer Type Directional Aid/PrecisionRunway Monitor
L G A ....... LaGuardia Airport
LIRL ....... Low Intensity Runway Lights
L L W A S..... Low Level Wind Shear Alert System
LLWAS NE . Low Level Wind Shear Alert System
Network Expansion
LLWAS−RS . Low Level Wind Shear Alert System
Relocation/Sustainment
L N A V...... Lateral Navigation
L O C ....... Localizer
L O P ....... Line−of−position
LORAN .... Long Range Navigation System
L P......... Localizer Performance
L P V ....... Localizer Performance with Vertical
Guidance
L U A W ..... Line Up and Wait
L Z......... Landing Zone
MAHWP . . . Missed Approach Holding Waypoint
M A P....... Missed Approach Point
M A W P ..... Missed Approach Waypoint
M D A ...... Minimum Descent Altitude
M E A....... Minimum En Route Altitude
MEARTS . . . Micro En Route Automated RadarTracking System
M E T A R .... Aviation Routine Weather Report
M H z ....... Megahertz
MIRL ...... Medium Intensity Runway Lights
M M ....... Middle Marker
M O A ...... Military Operations Area
MOCA ..... Minimum Obstruction Clearance Altitude
M R A ...... Minimum Reception Altitude
M R B....... Magnetic Reference Bearing
M S A....... Minimum Safe Altitude
M S A W ..... Minimum Safe Altitude Warning
M S L ....... Mean Sea Level
M T I ....... Moving Target Indicator
M T O S...... Mountain Obscuration
M T R....... Military Training Route
M V A....... Minimum Vectoring Altitude
M W A ...... Mountain Wave Activity
M W O ...... Meteorological Watch Office
N A S ....... National Airspace System
NASA ...... National Aeronautics and Space
Administration
N A V A I D.... Navigational Aid
NA VCEN . . . Coast Guard Navigation Center
NCWF ..... National Convective Weather ForecastAbbreviation/
AcronymMeaning
N D B ....... Nondirectional Radio Beacon
NEXRAD . . . Next Generation Weather Radar
NFDC ...... National Flight Data Center
N G A....... National Geospatial −Intelligence Agency
N M ........ Nautical Mile
NMAC ..... Near Midair Collision
NOAA ..... National Oceanic and Atmospheric
Administration
N O P A C .... North Pacific
NoPT ...... No Procedure Turn Required
N O T A M .... Notice to Airmen
N P A ....... Nonprecision Approach
N R S ....... Navigation Reference System
N S A ....... National Security Area
N S W....... No Significant Weather
N T A P ...... Notices to Airmen Publication
NTSB ...... National Transportation Safety Board
N T Z ....... No Transgression Zone
N W S....... National Weather Service
O A T ....... Outside Air Temperature
O B S ....... Omni−bearing Selector
O D P ....... Obstacle Departure Procedure
O I S ........ Operational Information System
O I S ........ Obstacle Identification Surface
O M ........ Outer Marker
O R D ....... Chicago O’Hare International Airport
P A......... Precision Approach
P A P I ....... Precision Approach Path Indicator
P A R ....... Precision Approach Radar
P A R ....... Preferred Arrival Route
P C......... Personal Computer
P/CG ....... Pilot/Controller Glossary
P D C ....... Pre−departure Clearance
P F D ....... Personal Flotation Device
PinS ....... Point−in−Space
PIREP ...... Pilot Weather Report
P O B ....... Persons on Board
POFZ ...... Precision Obstacle Free Zone
P O I ........ Principal Operations Inspector
P P S........ Precise Positioning Service
P R M ....... Precision Runway Monitor
P T......... Procedure Turn
QICP ...... Qualified Internet Communications
Provider
R A ........ Resolution Advisory
R A A ....... Remote Advisory Airport
RAIM ...... Receiver Autonomous Integrity Monitoring
AIM 10/12/17
Appendix 3 −4 Abbreviations/AcronymsAbbreviation/
AcronymMeaning
RAIS ...... Remote Airport Information Service
RBDT ...... Ribbon Display Terminals
RCAG ..... Remote Center Air/Ground
R C C ....... Rescue Coordination Center
RCLS ...... Runway Centerline Lighting System
R C O ....... Remote Communications Outlet
R D ........ Rotor Diameter
REIL ....... Runway End Identifier Lights
R E L ....... Runway Entrance Lights
R F M ....... Rotorcraft Flight Manual
R I L ........ Runway Intersection Lights
RLIM ...... Runway Light Intensity Monitor
R M I ....... Radio Magnetic Indicator
R N A V...... Area Navigation
R N P ....... Required Navigation Performance
R O C ....... Required Obstacle Clearance
R P A T ...... RNP Parallel Approach Runway
Transitions
R V R ....... Runway Visual Range
R V S M...... Reduced Vertical Separation Minimum
R W S L...... Runway Status Light
SAFO ...... Safety Alerts For Operators
S A M....... System Area Monitor
S A R ....... Search and Rescue
S A S ....... Stability Augmentation System
S A T R ...... Special Air Traffic Rules
SBAS ...... Satellite−based Augmentation System
SCAT−1
DGPS ...... Special Category I Differential GPS
S D F ....... Simplified Directional Facility
S F L........ Sequenced Flashing Lights
S F R ....... Special Flight Rules
SFRA ...... Special Flight Rules Area
SIAP ....... Standard Instrument Approach Procedure
S I D ........ Standard Instrument Departure
SIGMET .... Significant Meteorological Information
S M ........ Statute Mile
SMGCS .... Surface Movement Guidance Control
System
S N R ....... Signal−to−noise Ratio
SOIA ...... Simultaneous Offset Instrument
Approaches
S O P ....... Standard Operating Procedure
S P C ....... Storm Prediction Center
S P S........ Standard Positioning Service
S T A R ...... Standard Terminal Arrival
S T A R S ..... Standard Terminal AutomationReplacement SystemAbbreviation/
AcronymMeaning
STMP ...... Special Traffic Management Program
T A......... Traffic Advisory
T A A ....... Terminal Arrival Area
T A C ....... Terminal Area Chart
TACAN .... Tactical Air Navigation
T A F ....... Aerodrome Forecast
T A S ....... True Air Speed
TCAS ...... Traffic Alert and Collision Avoidance
System
T C H ....... Threshold Crossing Height
T D ........ Time Difference
TDLS ...... Tower Data Link System
TDWR ..... Terminal Doppler Weather Radar
T D Z ....... Touchdown Zone
TDZE ...... Touchdown Zone Elevation
TDZL ...... Touchdown Zone Lights
T E C ....... Tower En Route Control
T H L ....... Takeoff Hold Lights
TIBS ....... Telephone Information Briefing Service
T I S ........ Traffic Information Service
TIS−B...... Traffic Information Service −Broadcast
T L S ....... Transponder Landing System
T P P........ Terminal Procedures Publications
TRSA ...... Terminal Radar Service Area
T S O ....... Technical Standard Order
TWEB ..... Transcribed Weather Broadcast
TWIB ...... Terminal Weather Information for Pilots
System
U A ........ Unmanned Aircraft
U A S ....... Unmanned Aircraft System
U A V ....... Unmanned Aerial Vehicle
U F O ....... Unidentified Flying Object
U H F ....... Ultrahigh Frequency
U.S. ....... United States
USCG ...... United States Coast Guard
U T C ....... Coordinated Universal Time
U W S....... Urgent Weather SIGMET
V A R ....... V olcanic Activity Reporting
V A S I....... Visual Approach Slope Indicator
VCOA ..... Visual Climb Over the Airport
V D A....... Vertical Descent Angle
V D P ....... Visual Descent Point
V F R ....... Visual Flight Rules
VGSI ...... Visual Glide Slope Indicator
V H F ....... Very High Frequency
V I P ........ Video Integrator Processor
V M C ...... Visual Meteorological Conditions
AIM 10/12/17
Appendix 3 −5 Abbreviations/AcronymsAbbreviation/
AcronymMeaning
VMINI ...... Instrument flight minimum speed, utilizedin complying with minimum limit speed
requirements for instrument flight
V N A V...... Vertical Navigation
VNE....... Never exceed speed
VNEI....... Instrument flight never exceed speed,
utilized instead of V NE for compliance with
maximum limit speed requirements forinstrument flight
V O R ....... Very High Frequency Omni −directional
Range
VORTAC . . . VHF Omni −directional Range/Tactical Air
Navigation
V O T ....... VOR Test Facility
V R ........ VFR Military Training Route
VREF....... The reference landing approach speed,usually about 1.3 times V
so plus 50 percent
of the wind gust speed in excess of themean wind speed.
VSO........ The stalling speed or the minimum steady
flight speed in the landing configuration at
maximum weight.
V T F ....... Vector to Final
V V ........ Vertical VisibilityAbbreviation/
AcronymMeaning
V V I ....... Vertical Velocity Indicator
VY........ Speed for best rate of climb
VYI........ Instrument climb speed, utilized instead ofV
Y for compliance with the climb
requirements for instrument flight
W A ........ AIRMET
W A A S ..... Wide Area Augmentation System
W F O....... Weather Forecast Office
WGS−8 4.... World Geodetic System of 1984
W M O ...... World Meteorological Organization
WMS . . Wide−Area Master Station
WMSC ..... Weather Message Switching Center
WMSCR .... Weather Message Switching Center
Replacement
W P ........ Waypoint
W R A ...... Weather Reconnaissance Area
W R S....... Wide−Area Ground Reference Station
W S ........ SIGMET
WSO ...... Weather Service Office
W S P ....... Weather System Processor
W S T ....... Convective Significant Meteorological
Information
W W ....... Severe Weather Watch Bulletin
Pilot/Controller Glossary 10/12/17
PCG−1PILOT/CONTROLLER
GLOSSARY
PURPOSE
a.This Glossary was compiled to promote a common understanding of the terms used in the Air Traffic
Control system. It includes those terms which are intended for pilot/controller communications. Those termsmost frequently used in pilot/controller communications are printed in bold italics . The definitions are primarily
defined in an operational sense applicable to both users and operators of the National Airspace System. Use ofthe Glossary will preclude any misunderstandings concerning the system’s design, function, and purpose.
b.Because of the international nature of flying, terms used in the Lexicon, published by the International
Civil Aviation Organization (ICAO), are included when they differ from FAA definitions. These terms arefollowed by “[ICAO].” For the reader’s convenience, there are also cross references to related terms in other parts
of the Glossary and to other documents, such as the Code of Federal Regulations (CFR) and the AeronauticalInformation Manual (AIM).
c.This Glossary will be revised, as necessary, to maintain a common understanding of the system.
EXPLANATION OF CHANGES
d.Terms Added:
RUNWAY CONDITION CODES (RWYCC)
RUNWAY CONDITION REPORT (RWYCR)
SPECIAL AIR TRAFFIC RULES (SATR)
WEATHER RECONNAISSANCE AREA (WRA)
e.Terms Modified:
BRAKING ACTION (GOOD, FAIR, POOR, OR NIL)
BRAKING ACTION ADVISORIES
ENHANCED FLIGHT VISION SYSTEM (EFVS)
ESTABLISHED
PRECIPITATION RADAR WEATHER DESCRIPTIONS
RADAR IDENTIFICATION
f.Editorial/format changes were made where necessary. Revision bars were not used due to the insignificant
nature of the changes.
Pilot/Controller Glossary10/12/17
PCG A−1A
AAI−
(See ARRIVAL AIRCRAFT INTERVAL.)
AAR−
(See AIRPORT ARRIVAL RATE.)
ABBREVIATED IFR FLIGHT PLANS − An
authorization by A TC requiring pilots to submit only
that information needed for the purpose of ATC. Itincludes only a small portion of the usual IFR flightplan information. In certain instances, this may beonly aircraft identification, location, and pilotrequest. Other information may be requested ifneeded by ATC for separation/control purposes. It isfrequently used by aircraft which are airborne anddesire an instrument approach or by aircraft which are
on the ground and desire a climb to VFR-on-top.
(See VFR-ON-TOP.)
(Refer to AIM.)
ABEAM− An aircraft is “abeam” a fix, point, or
object when that fix, point, or object is approximately
90 degrees to the right or left of the aircraft track.Abeam indicates a general position rather than aprecise point.
ABORT− To terminate a preplanned aircraft
maneuver; e.g., an aborted takeoff.
ACC [ICAO] −
(See ICAO term AREA CONTROL CENTER.)
ACCELERATE-STOP DISTANCE AV AILABLE −
The runway plus stopway length declared availableand suitable for the acceleration and deceleration ofan airplane aborting a takeoff.
ACCELERATE-STOP DISTANCE A V AILABLE
[ICAO]− The length of the take-off run available plus
the length of the stopway if provided.
ACDO−
(See AIR CARRIER DISTRICT OFFICE.)
ACKNOWLEDGE − Let me know that you have
received and understood this message.
ACL−
(See AIRCRAFT LIST.)
ACLS−
(See AUTOMATIC CARRIER LANDING
SYSTEM.)ACLT−
(See ACTUAL CALCULATED LANDING TIME.)
ACROBATIC FLIGHT − An intentional maneuver
involving an abrupt change in an aircraft’ s attitude, an
abnormal attitude, or abnormal a cceleration not
necessary for normal flight.
(See ICAO term ACROBATIC FLIGHT.)
(Refer to 14 CFR Part 91.)
ACROBATIC FLIGHT [ICAO] − Maneuvers inten-
tionally performed by an aircraft involving an abrupt
change in its attitude, an abnormal attitude, or anabnormal variation in speed.
ACTIVE RUNWAY −
(See RUNWAY IN USE/ACTIVE RUNWAY/DUTY
RUNWAY.)
ACTUAL CALCULATED LANDING TIME −
ACLT is a flight’s frozen calculated landing time. Anactual time determined at freeze calculated landingtime (FCLT) or meter list display interval (MLDI) for
the adapted vertex for each arrival aircraft based uponrunway configuration, airport acceptance rate, airportarrival delay period, and other metered arrivalaircraft. This time is either the vertex time of arrival(VTA) of the aircraft or the tentative calculatedlanding time (TCLT)/ACLT of the previous aircraftplus the arrival aircraft interval (AAI), whichever islater. This time will not be updated in response to the
aircraft’s progress.
ACTUAL NA VIGATION PERFORMANCE
(ANP)−
(See REQUIRED NAVIGATION
PERFORMANCE.)
ADDITIONAL SERVICES − Advisory information
provided by A TC which includes but is not limited to
the following:
a.Traffic advisories.
b.Vectors, when requested by the pilot, to assist
aircraft receiving traffic advisories to avoid observed
traffic.
c.Altitude deviation information of 300 feet or
more from an assigned altitude as observed on averified (reading correctly) automatic altitudereadout (Mode C).
d.Advisories that traffic is no longer a factor.
Pilot/Controller Glossary 10/12/17
PCG A−2e.Weather and chaff information.
f.Weather assistance.
g.Bird activity information.
h.Holding pattern surveillance. Additional ser-
vices are provided to the extent possible contingentonly upon the controller’s capability to fit them intothe performance of higher priority duties and on thebasis of limitations of the radar, volume of traffic,frequency congestion, and controller workload. Thecontroller has complete discretion for determining if
he/she is able to provide or continue to provide aservice in a particular case. The controller’s reasonnot to provide or continue to provide a service in aparticular case is not subject to question by the pilotand need not be made known to him/her.
(See TRAFFIC ADVISORIES.)
(Refer to AIM.)
ADF−
(See AUTOMATIC DIRECTION FINDER.)
ADIZ−
(See AIR DEFENSE IDENTIFICATION ZONE.)
ADLY−
(See ARRIVAL DELAY.)
ADMINISTRATOR − The Federal Aviation Admin-
istrator or any person to whom he/she has delegatedhis/her authority in the matter concerned.
ADR−
(See AIRPORT DEPARTURE RATE.)
ADS [ICAO] −
(See ICAO term AUTOMATIC DEPENDENT
SURVEILLANCE.)
ADS−B−
(See AUTOMATIC DEPENDENT
SURVEILLANCE −BROADCAST.)
ADS−C−
(See AUTOMATIC DEPENDENT
SURVEILLANCE −CONTRACT.)
ADVISE INTENTIONS − Tell me what you plan to
do.
ADVISORY − Advice and information provided to
assist pilots in the safe conduct of flight and aircraft
movement.
(See ADVISORY SERVICE.)ADVISORY FREQUENCY − The appropriate fre-
quency to be used for Airport Advisory Service.
(See LOCAL AIRPORT ADVISORY.)
(See UNICOM.)
(Refer to ADVISORY CIRCULAR NO. 90-42.)
(Refer to AIM.)
ADVISORY SERVICE − Advice and information
provided by a facility to assist pilots in the safeconduct of flight and aircraft movement.
(See ADDITIONAL SERVICES.)
(See LOCAL AIRPORT ADVISORY.)
(See RADAR ADVISORY.)
(See SAFETY ALERT.)
(See TRAFFIC ADVISORIES.)
(Refer to AIM.)
AERIAL REFUELING − A procedure used by the
military to transfer fuel from one aircraft to anotherduring flight.
(Refer to VFR/IFR Wall Planning Charts.)
AERODROME − A defined area on land or water
(including any buildings, installations and equip-ment) intended to be used either wholly or in part for
the arrival, departure, and movement of aircraft.
AERODROME BEACON [ICAO] − Aeronautical
beacon used to indicate the location of an aerodrome
from the air.
AERODROME CONTROL SER VICE [ICAO] − Air
traffic control service for aerodrome traffic.
AERODROME CONTROL TOWER [ICAO] − A
unit established to provide air traffic control serviceto aerodrome traffic.
AERODROME ELEV ATION [ICAO] − The eleva-
tion of the highest point of the landing area.
AERODROME TRAFFIC CIRCUIT [ICAO] − The
specified path to be flown by aircraft operating in the
vicinity of an aerodrome.
AERONAUTICAL BEACON − A visual NA V AID
displaying flashes of white and/or colored light toindicate the location of an airport, a heliport, alandmark, a certain point of a Federal airway inmountainous terrain, or an obstruction.
(See AIRPORT ROTATING BEACON.)
(Refer to AIM.)
AERONAUTICAL CHART − A map used in air
navigation containing all or part of the following:topographic featur es, hazards and obstructions,
Pilot/Controller Glossary10/12/17
PCG A−3navigation aids, navigation routes, designated
airspace, and airports. Commonly used aeronauticalcharts are:
a.Sectional Aeronautical Charts (1:500,000) −
Designed for visual navigation of slow or mediumspeed aircraft. Topographic information on thesecharts features the portrayal of relief and a judiciousselection of visual check points for VFR flight.Aeronautical information includes visual and radioaids to navigation, airports, controlled airspace,restricted areas, obstructions, and related data.
b.VFR Terminal Area Charts (1:250,000) −
Depict Class B airspace which provides for thecontrol or segregation of all the aircraft within ClassB airspace. The chart depicts topographic informa-tion and aeronautical information which includesvisual and radio aids to navigation, airports,
controlled airspace, restricted areas, obstructions,and related data.
c.En Route Low Altitude Charts − Provide
aeronautical information for en route instrumentnavigation (IFR) in the low altitude stratum.Information includes the portrayal of airways, limitsof controlled airspace, position identification andfrequencies of radio aids, selected airports, minimum
en route and minimum obstruction clearancealtitudes, airway distances, reporting points, re-stricted areas, and related data. Area charts, which are
a part of this series, furnish terminal data at a largerscale in congested areas.
d.En Route High Altitude Charts − Provide
aeronautical information for en route instrumentnavigation (IFR) in the high altitude stratum.Information includes the portrayal of jet routes,identification and frequencies of radio aids, selectedairports, distances, time zones, special use airspace,and related information.
e.Instrument Approach Procedure (IAP) Charts−
Portray the aeronautical data which is required toexecute an instrument approach to an airport. Thesecharts depict the procedures, including all relateddata, and the airport diagram. Each procedure isdesignated for use with a specific type of electronicnavigation system including NDB, TACAN, VOR,ILS RNA V and GLS. These charts are identified bythe type of navigational aid(s)/equipment required toprovide final approach guidance.f.Instrument Departure Procedure (DP) Charts −
Designed to expedite clearance delivery and tofacilitate transition between takeoff and en routeoperations. Each DP is presented as a separate chartand may serve a single airport or more than oneairport in a given geographical location.
g.Standard Terminal Arrival (STAR) Charts −
Designed to expedite air traffic control arrivalprocedures and to facilitate transition between enroute and instrument approach operations. EachSTAR procedure is presented as a separate chart andmay serve a single airport or more than one airport ina given geographical location.
h.Airport Taxi Charts − Designed to expedite the
efficient and safe flow of ground traffic at an airport.
These charts are identified by the official airportname; e.g., Ronald Reagan Washington NationalAirport.
(See ICAO term AERONAUTICAL CHART.)
AERONAUTICAL CHAR T [ICAO] − A representa-
tion of a portion of the earth, its culture and relief,specifically designated to meet the requirements ofair navigation.
AERONAUTICAL INFORMATION MANUAL
(AIM)− A primary FAA publication whose purpose
is to instruct airmen about operating in the NationalAirspace System of the U.S. It provides basic flightinformation, ATC Procedures and general instruc-tional information concerning health, medical facts,factors affecting flight safety, accident and hazardreporting, and types of aeronautical charts and theiruse.
AERONAUTICAL INFORMATION PUBLICA-
TION (AIP) [ICAO] − A publication issued by or with
the authority of a State and containing aeronauticalinformation of a lasting character essential to airnavigation.
(See CHART SUPPLEMENT U.S.)
AFFIRMA TIVE− Yes.
AFIS−
(See AUTOMATIC FLIGHT INFORMATION
SERVICE − ALASKA FSSs ONLY.)
AFP−
(See AIRSPACE FLOW PROGRAM.)
AIM−
(See AERONAUTICAL INFORMATION
MANUAL.)
Pilot/Controller Glossary 10/12/17
PCG A−4AIP [ICAO] −
(See ICAO term AERONAUTICAL
INFORMATION PUBLICATION.)
AIR CARRIER DISTRICT OFFICE − An FAA field
office serving an assigned geographical area, staffedwith Flight Standards personnel serving the aviationindustry and the general public on matters related tothe certification and operation of scheduled aircarriers and other large aircraft operations.
AIR DEFENSE EMERGENCY − A military emer-
gency condition declared by a designated authority.This condition exists when an attack upon thecontinental U.S., Alaska, Canada, or U.S. installa-tions in Greenland by hostile aircraft or missiles isconsidered probable, is imminent, or is taking place.
(Refer to AIM.)
AIR DEFENSE IDENTIFICA TION ZONE (ADIZ) −
The area of airspace over land or water, extendingupward from the surface, within which the readyidentification, the location, and the control of aircraft
are required in the interest of national security.
a.Domestic Air Defense Identification Zone. An
ADIZ within the United States along an international
boundary of the United States.
b.Coastal Air Defense Identification Zone. An
ADIZ over the coastal waters of the United States.
c.Distant Early Warning Identification Zone
(DEWIZ). An ADIZ over the coastal waters of theState of Alaska.
d.Land−Based Air Defense Identification Zone.
An ADIZ over U.S. metropolitan areas, which isactivated and deactivated as needed, with dimen-sions, activation dates and other relevant information
disseminated via NOTAM.
Note: ADIZ locations and operating and flight plan
requirements for civil aircraft operations arespecified in 14 CFR Part 99.
(Refer to AIM.)
AIR NA VIGATION FACILITY − Any facility used
in, available for use in, or designed for use in, aid ofair navigation, including landing areas, lights, anyapparatus or equipment for disseminating weatherinformation, for signaling, for radio-directionalfinding, or for radio or other electrical communica-tion, and any other structure or mechanism having asimilar purpose for guiding or controlling flight in the
air or the landing and takeoff of aircraft.
(See NAVIGATIONAL AID.)AIR ROUTE SURVEILLANCE RADAR − Air route
traffic control center (ARTCC) radar used primarilyto detect and display an aircraft’s position while enroute between terminal areas. The ARSR enablescontrollers to provide radar air traffic control service
when aircraft are within the ARSR coverage. In some
instances, ARSR may enable an ARTCC to provideterminal radar services similar to but usually morelimited than those provided by a radar approachcontrol.
AIR ROUTE TRAFFIC CONTROL CENTER
(ARTCC) − A facility established to provide air traffic
control service to aircraft operating on IFR flightplans within controlled airspace and principallyduring the en route phase of flight. When equipmentcapabilities and controller workload permit, certainadvisory/assistance services may be provided to VFR
aircraft.
(See EN ROUTE AIR TRAFFIC CONTROL
SERVICES.)
(Refer to AIM.)
AIR TAXI − Used to describe a helicopter/VTOL
aircraft movement conducted above the surface butnormally not above 100 feet AGL. The aircraft mayproceed either via hover taxi or flight at speeds more
than 20 knots. The pilot is solely responsible forselecting a safe airspeed/altitude for the operationbeing conducted.
(See HOVER TAXI.)
(Refer to AIM.)
AIR TRAFFIC − Aircraft operating in the air or on an
airport surface, exclusive of loading ramps andparking areas.
(See ICAO term AIR TRAFFIC.)
AIR TRAFFIC [ICAO] − All aircraft in flight or
operating on the maneuvering area of an aerodrome.
AIR TRAFFIC CLEARANCE − An authorization by
air traffic control for the purpose of preventingcollision between known aircraft, for an aircraft toproceed under specified traffic conditions withincontrolled airspace. The pilot-in-command of anaircraft may not deviate from the provisions of avisual flight rules (VFR) or instrument flight rules(IFR) air traffic clearance except in an emergency orunless an amended clearance has been obtained.Additionally, the pilot may request a differentclearance from that which has been issued by airtraffic control (ATC) if information available to thepilot makes another course of action more practicable
Pilot/Controller Glossary10/12/17
PCG A−5or if aircraft equipment limitations or company
procedures forbid compliance with the clearanceissued. Pilots may also request clarification oramendment, as appropriate, any time a clearance isnot fully understood, or considered unacceptablebecause of safety of flight. Controllers should, insuch instances and to the extent of operationalpracticality and safety, honor the pilot’s request.14 CFR Part 91.3(a) states: “The pilot in commandof an aircraft is directly responsible for, and is thefinal authority as to, the operation of that aircraft.”THE PILOT IS RESPONSIBLE TO REQUEST ANAMENDED CLEARANCE if ATC issues aclearance that would cause a pilot to deviate from arule or regulation, or in the pilot’s opinion, wouldplace the aircraft in jeopardy.
(See ATC INSTRUCTIONS.)
(See ICAO term AIR TRAFFIC CONTROL
CLEARANCE.)
AIR TRAFFIC CONTROL − A service operated by
appropriate authority to promote the safe, orderly and
expeditious flow of air traffic.
(See ICAO term AIR TRAFFIC CONTROL
SERVICE.)
AIR TRAFFIC CONTROL CLEARANCE [ICAO] −
Authorization for an aircraft to proceed underconditions specified by an air traffic control unit.
Note 1: For convenience, the term air traf fic control
clearance is frequently abbreviated to clearance
when used in appropriate contexts.
Note 2: The abbreviated term clearance may be
prefixed by the words taxi, takeoff, departure, en
route, approach or landing to indicate the particular
portion of flight to which the air traffic control clear-
ance relates.
AIR TRAFFIC CONTROL SER VICE−
(See AIR TRAFFIC CONTROL.)
AIR TRAFFIC CONTROL SERVICE [ICAO] − A
service provided for the purpose of:
a.Preventing collisions:
1.Between aircraft; and
2.On the maneuvering area between aircraft
and obstructions.
b.Expediting and maintaining an orderly flow of
air traffic.AIR TRAFFIC CONTROL SPECIALIST − A person
authorized to provide air traffic control service.
(See AIR TRAFFIC CONTROL.)
(See FLIGHT SERVICE STATION.)(See ICAO term CONTROLLER.)
AIR TRAFFIC CONTROL SYSTEM COMMAND
CENTER (ATCSCC) − An Air Traffic Tactical
Operations facility responsible for monitoring andmanaging the flow of air traf fic throughout the NAS,
producing a safe, orderly, and expeditious flow oftraffic while minimizing delays. The followingfunctions are located at the ATCSCC:
a.Central Altitude Reservation Function
(CARF). Responsible for coordinating, planning,and approving special user requirements under theAltitude Reservation (ALTRV) concept.
(See ALTITUDE RESERVATION.)
b.Airport Reservation Office (ARO). Monitors
the operation and allocation of reservations forunscheduled operations at airports designated by the
Administrator as High Density Airports. Theseairports are generally known as slot controlledairports. The ARO allocates reservations on a firstcome, first served basis determined by the time therequest is received at the ARO.
(Refer to 14 CFR Part 93.)
(See CHART SUPPLEMENT U.S.)
c.U.S. Notice to Airmen (NOTAM) Office.
Responsible for collecting, maintaining, and distrib-uting NOTAMs for the U.S. civilian and military, aswell as international aviation communities.
(See NOTICE TO AIRMEN.)
d.Weather Unit. Monitor all aspects of weather
for the U.S. that might affect aviation including cloud
cover, visibility, winds, precipitation, thunderstorms,
icing, turbulence, and more. Provide forecasts based
on observations and on discussions with meteorolo-gists from various National Weather Service offices,FAA facilities, airlines, and private weather services.
AIR TRAFFIC SERVICE − A generic term meaning:
a.Flight Information Service.
b.Alerting Service.
c.Air Traffic Advisory Service.
d.Air Traffic Control Service:
1.Area Control Service,
2.Approach Control Service, or
3.Airport Control Service.
AIR TRAFFIC SERVICE (ATS) ROUTES − The
term “ATS Route” is a generic term that includes
Pilot/Controller Glossary 10/12/17
PCG A−6“VOR Federal airways,” “colored Federal airways,”
“jet routes,” and “RNA V routes.” The term “ATSroute” does not replace these more familiar routenames, but serves only as an overall title when listing
the types of routes that comprise the United Statesroute structure.
AIRBORNE − An aircraft is considered airborne
when all parts of the aircraft are off the ground.
AIRBORNE DELAY − Amount of delay to be
encountered in airborne holding.
AIRCRAFT − Device(s) that are used or intended to
be used for flight in the air , and when used in air traffic
control terminology, may include the flight crew.
(See ICAO term AIRCRAFT.)
AIRCRAFT [ICAO] − Any machine that can derive
support in the atmosphere from the reactions of the air
other than the reactions of the air against the earth’s
surface.
AIRCRAFT APPROACH CATEGORY − A
grouping of aircraft based on a speed of 1.3 times the
stall speed in the landing configuration at maximumgross landing weight. An aircraft must fit in only one
category. If it is necessary to maneuver at speeds inexcess of the upper limit of a speed range for acategory, the minimums for the category for thatspeed must be used. For example, an aircraft whichfalls in Category A, but is circling to land at a speedin excess of 91 knots, must use the approachCategory B minimums when circling to land. Thecategories are as follows:
a.Category A − Speed less than 91 knots.
b.Category B − Speed 91 knots or more but less
than 121 knots.
c.Category C − Speed 121 knots or more but less
than 141 knots.
d.Category D − Speed 141 knots or more but less
than 166 knots.
e.Category E − Speed 166 knots or more.
(Refer to 14 CFR Part 97.)
AIRCRAFT CLASSES − For the purposes of Wake
Turbulence Separation Minima, ATC classifiesaircraft as Super, Heavy, Lar ge, and Small as follows:
a.Super. The Airbus A-380-800 (A388) and the
Antonov An-225 (A225) are classified as super.
b.Heavy− Aircraft capable of takeoff weights of
300,000 pounds or more whether or not they areoperating at this weight during a particular phase of
flight.
c.Large− Aircraft of more than 41,000 pounds,
maximum certificated takeoff weight, up to but notincluding 300,000 pounds.
d.Small− Aircraft of 41,000 pounds or less
maximum certificated takeoff weight.
(Refer to AIM.)
AIRCRAFT CONFLICT − Predicted conflict, within
EDST of two aircraft, or between aircraft andairspace. A Red alert is used for conflicts when thepredicted minimum separation is 5 nautical miles orless. A Yellow alert is used when the predictedminimum separation is between 5 and approximately
12 nautical miles. A Blue alert is used for conflictsbetween an aircraft and predefined airspace.
(See EN ROUTE DECISION SUPPORT
TOOL .)
AIRCRAFT LIST (ACL) − A view available with
EDST that lists aircraft currently in or predicted to be
in a particular sector’s airspace. The view containstextual flight data information in line format and may
be sorted into various orders based on the specificneeds of the sector team.
(See EN ROUTE DECISION SUPPORT
TOOL .)
AIRCRAFT SURGE L AUNCH AND
RECOVERY − Procedures used at USAF bases to
provide increased launch and recovery rates ininstrument flight rules conditions. ASLAR is basedon:
a.Reduced separation between aircraft which is
based on time or distance. Standard arrival separation
applies between participants including multipleflights until the DRAG point. The DRAG point is apublished location on an ASLAR approach whereaircraft landing second in a formation slows to apredetermined airspeed. The DRAG point is thereference point at which MARSA applies asexpanding elements effect separation within a flightor between subsequent participating flights.
b.ASLAR procedures shall be covered in a Letter
of Agreement between the responsible USAFmilitary ATC facility and the concerned FederalAviation Administration facility. Initial ApproachFix spacing requirements are normally addressed asa minimum.
Pilot/Controller Glossary10/12/17
PCG A−7AIRMEN’S METEOROLOGICAL
INFORMA TION−
(See AIRMET.)
AIRMET − In-flight weather advisories issued only
to amend the area forecast concerning weatherphenomena which are of operational interest to allaircraft and potentially hazardous to aircraft havinglimited capability because of lack of equipment,instrumentation, or pilot qualifications. AIRMETsconcern weather of less severity than that covered by
SIGMETs or Convective SIGMETs. AIRMETscover moderate icing, moderate turbulence, sustained
winds of 30 knots or more at the surface, widespread
areas of ceilings less than 1,000 feet and/or visibilityless than 3 miles, and extensive mountainobscurement.
(See AWW.)
(See CONVECTIVE SIGMET.)
(See CWA.)
(See SIGMET.)
(Refer to AIM.)
AIRPORT − An area on land or water that is used or
intended to be used for the landing and takeoff ofaircraft and includes its buildings and facilities, ifany.
AIRPORT ADVISOR Y AREA− The area within ten
miles of an airport without a control tower or wherethe tower is not in operation, and on which a FlightService Station is located.
(See LOCAL AIRPORT ADVISORY.)
(Refer to AIM.)
AIRPORT ARRIV AL RATE (AAR) − A dynamic
input parameter specifying the number of arrivingaircraft which an airport or airspace can accept fromthe ARTCC per hour. The AAR is used to calculatethe desired interval between successive arrivalaircraft.
AIRPORT DEPAR TURE RATE (ADR)− A dynamic
parameter specifying the number of aircraft whichcan depart an airport and the airspace can accept perhour.
AIRPORT ELEV ATION − The highest point of an
airport’s usable runways measured in feet from mean
sea level.
(See TOUCHDOWN ZONE ELEVATION.)
(See ICAO term AERODROME ELEVATION.)AIRPORT LIGHTING − Various lighting aids that
may be installed on an airport. Types of airportlighting include:
a.Approach Light System (ALS) − An airport
lighting facility which provides visual guidance tolanding aircraft by radiating light beams in adirectional pattern by which the pilot aligns theaircraft with the extended centerline of the runway on
his/her final approach for landing. Condenser-Discharge Sequential Flashing Lights/SequencedFlashing Lights may be installed in conjunction with
the ALS at some airports. Types of Approach LightSystems are:
1.ALSF-1− Approach Light System with
Sequenced Flashing Lights in ILS Cat-I configura-tion.
2.ALSF-2− Approach Light System with
Sequenced Flashing Lights in ILS Cat-II configura-tion. The ALSF-2 may operate as an SSALR whenweather conditions permit.
3.SSALF− Simplified Short Approach Light
System with Sequenced Flashing Lights.
4.SSALR− Simplified Short Approach Light
System with Runway Alignment Indicator Lights.
5.MALSF− Medium Intensity Approach Light
System with Sequenced Flashing Lights.
6.MALSR− Medium Intensity Approach Light
System with Runway Alignment Indicator Lights.
7.RLLS− Runway Lead-in Light System
Consists of one or more series of flashing lightsinstalled at or near ground level that provides positive
visual guidance along an approach path, eithercurving or straight, where special problems exist with
hazardous terrain, obstructions, or noise abatementprocedures.
8.RAIL− Runway Alignment Indicator Lights −
Sequenced Flashing Lights which are installed onlyin combination with other light systems.
9.ODALS− Omnidirectional Approach Light-
ing System consists of seven omnidirectionalflashing lights located in the approach area of anonprecision runway. Five lights are located on therunway centerline extended with the first lightlocated 300 feet from the threshold and extending atequal intervals up to 1,500 feet from the threshold.The other two lights are located, one on each side ofthe runway threshold, at a lateral distance of 40 feetfrom the runway edge, or 75 feet from the runway
Pilot/Controller Glossary 10/12/17
PCG A−8edge when installed on a runway equipped with a
V ASI.
(Refer to FAA Order JO 6850.2, VISUAL
GUIDANCE LIGHTING SYSTEMS.)
b.Runway Lights/Runway Edge Lights − Lights
having a prescribed angle of emission used to definethe lateral limits of a runway. Runway lights areuniformly spaced at intervals of approximately 200feet, and the intensity may be controlled or preset.
c.Touchdown Zone Lighting − Two rows of
transverse light bars located symmetrically about the
runway centerline normally at 100 foot intervals. The
basic system extends 3,000 feet along the runway.
d.Runway Centerline Lighting − Flush centerline
lights spaced at 50-foot intervals beginning 75 feetfrom the landing threshold and extending to within 75
feet of the opposite end of the runway.
e.Threshold Lights − Fixed green lights arranged
symmetrically left and right of the runway centerline,
identifying the runway threshold.
f.Runway End Identifier Lights (REIL) − Two
synchronized flashing lights, one on each side of the
runway threshold, which provide rapid and positiveidentification of the approach end of a particularrunway.
g.Visual Approach Slope Indicator (V ASI) − An
airport lighting facility providing vertical visualapproach slope guidance to aircraft during approachto landing by radiating a directional pattern of highintensity red and white focused light beams whichindicate to the pilot that he/she is “on path” if he/she
sees red/white, “above path” if white/white, and“below path” if red/red. Some airports serving largeaircraft have three-bar V ASIs which provide twovisual glide paths to the same runway.
h.Precision Approach Path Indicator (P API)− An
airport lighting facility, similar to V ASI, providingvertical approach slope guidance to aircraft duringapproach to landing. PAPIs consist of a single row of
either two or four lights, normally installed on the left
side of the runway, and have an ef fective visual range
of about 5 miles during the day and up to 20 miles atnight. PAPIs radiate a directional pattern of highintensity red and white focused light beams whichindicate that the pilot is “on path” if the pilot sees an
equal number of white lights and red lights, withwhite to the left of the red; “above path” if the pilotsees more white than red lights; and “below path” ifthe pilot sees more red than white lights.i.Boundary Lights− Lights defining the perimeter
of an airport or landing area.
(Refer to AIM.)
AIRPORT MARKING AIDS − Markings used on
runway and taxiway surfaces to identify a specificrunway, a runway threshold, a centerline, a hold line,
etc. A runway should be marked in accordance with
its present usage such as:
a.Visual.
b.Nonprecision instrument.
c.Precision instrument.
(Refer to AIM.)
AIRPORT REFERENCE POINT (ARP) − The
approximate geometric center of all usable runwaysurfaces.
AIRPORT RESERV ATION OFFICE − Office
responsible for monitoring the operation of slotcontrolled airports. It receives and processes requests
for unscheduled operations at slot controlled airports.
AIRPORT ROTATING BEACON − A visual
NA V AID operated at many airports. At civil airports,alternating white and green flashes indicate thelocation of the airport. At military airports, thebeacons flash alternately white and green, but aredifferentiated from civil beacons by dualpeaked (two
quick) white flashes between the green flashes.
(See INSTRUMENT FLIGHT RULES.)
(See SPECIAL VFR OPERATIONS.)
(See ICAO term AERODROME BEACON.)
(Refer to AIM.)
AIRPORT STREAM FILTER (ASF) − An on/off
filter that allows the conflict notification function tobe inhibited for arrival streams into single or multipleairports to prevent nuisance alerts.
AIRPORT SURFACE DETECTION EQUIPMENT
(ASDE)− Surveillance equipment specifically de-
signed to detect aircraft, vehicular traffic, and otherobjects, on the surface of an airport, and to present the
image on a tower display. Used to augment visualobservation by tower personnel of aircraft and/orvehicular movements on runways and taxiways.There are three ASDE systems deployed in the NAS:
a.ASDE−3− a Surface Movement Radar.
b.ASDE−X− a system that uses an X −band
Surface Movement Radar, multilateration, andADS−B.
c.Airport Surface Surveillance Capability
(ASSC)− A system that uses Surface Movement
Radar, multilateration, and ADS −B.
Pilot/Controller Glossary10/12/17
PCG A−9AIRPORT SURVEILLANCE RADAR − Approach
control radar used to detect and display an aircraft’sposition in the terminal area. ASR provides range and
azimuth information but does not provide elevationdata. Coverage of the ASR can extend up to 60 miles.
AIRPORT TAXI CHARTS −
(See AERONAUTICAL CHART.)
AIRPORT TRAFFIC CONTROL SERVICE − A
service provided by a control tower for aircraftoperating on the movement area and in the vicinity of
an airport.
(See MOVEMENT AREA.)
(See TOWER.)(See ICAO term AERODROME CONTROL
SERVICE.)
AIRPORT TRAFFIC CONTROL T OWER−
(See TOWER.)
AIRSPACE CONFLICT − Predicted conflict of an
aircraft and active Special Activity Airspace (SAA).
AIRSPACE FLOW PROGRAM (AFP) − AFP is a
Traffic Management (TM) process administered bythe Air Traffic Control System Command Center(ATCSCC) where aircraft are assigned an ExpectDeparture Clearance Time (EDCT) in order tomanage capacity and demand for a specific area of the
National Airspace System (NAS). The purpose of theprogram is to mitigate the effects of en routeconstraints. It is a flexible program and may beimplemented in various forms depending upon theneeds of the air traffic system.
AIRSPACE HIERARCHY − Within the airspace
classes, there is a hierarchy and, in the event of anoverlap of airspace: Class A preempts Class B, Class
B preempts Class C, Class C preempts Class D, Class
D preempts Class E, and Class E preempts Class G.
AIRSPEED − The speed of an aircraft relative to its
surrounding air mass. The unqualified term“airspeed” means one of the following:
a.Indicated Airspeed − The speed shown on the
aircraft airspeed indicator. This is the speed used inpilot/controller communications under the generalterm “airspeed.”
(Refer to 14 CFR Part 1.)
b.True Airspeed − The airspeed of an aircraft
relative to undisturbed air. Used primarily in flightplanning and en route portion of flight. When used inpilot/controller communications, it is referred to as
“true airspeed” and not shortened to “airspeed.”
AIRSTART − The starting of an aircraft engine while
the aircraft is airborne, preceded by engine shutdownduring training flights or by actual engine failure.
AIRWAY − A Class E airspace area established in the
form of a corridor, the centerline of which is definedby radio navigational aids.
(See FEDERAL AIRWAYS.)
(See ICAO term AIRWAY.)
(Refer to 14 CFR Part 71.)
(Refer to AIM.)
AIRWAY [ICAO] − A control area or portion thereof
established in the form of corridor equipped withradio navigational aids.
AIRWAY BEACON − Used to mark airway segments
in remote mountain areas. The light flashes MorseCode to identify the beacon site.
(Refer to AIM.)
AIT−
(See AUTOMATED INFORMATION
TRANSFER.)
ALERFA (Alert Phase) [ICAO] − A situation wherein
apprehension exists as to the safety of an aircraft and
its occupants.
ALERT− A notification to a position that there
is an aircraft-to-aircraft or aircraft-to-airspaceconflict, as detected by Automated ProblemDetection (APD).
ALERT AREA −
(See SPECIAL USE AIRSPACE.)
ALERT NOTICE (ALNOT) − A request originated
by a flight service station (FSS) or an air route trafficcontrol center (ARTCC) for an extensive commu-nication search for overdue, unreported, or missingaircraft.
ALERTING SER VICE− A service provided to notify
appropriate organizations regarding aircraft in needof search and rescue aid and assist such or ganizations
as required.
ALNOT−
(See ALERT NOTICE.)
ALONG−TRACK DISTANCE (ATD)− The hori-
zontal distance between the aircraft’s current position
and a fix measured by an area navigation system that
is not subject to slant range errors.
Pilot/Controller Glossary 10/12/17
PCG A−10ALPHANUMERIC DISPLAY − Letters and numer-
als used to show identification, altitude, beacon code,
and other information concerning a target on a radardisplay.
(See AUTOMATED RADAR TERMINAL
SYSTEMS.)
ALTERNATE AERODROME [ICAO] − An aero-
drome to which an aircraft may proceed when itbecomes either impossible or inadvisable to proceed
to or to land at the aerodrome of intended landing.
Note: The aerodrome from which a flight departs
may also be an en-route or a destination alternate
aerodrome for the flight.
ALTERNATE AIRPORT − An airport at which an
aircraft may land if a landing at the intended airportbecomes inadvisable.
(See ICAO term ALTERNATE AERODROME.)
ALTIMETER SETTING − The barometric pressure
reading used to adjust a pressure altimeter forvariations in existing atmospheric pressure or to thestandard altimeter setting (29.92).
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
ALTITUDE − The height of a level, point, or object
measured in feet Above Ground Level (AGL) or from
Mean Sea Level (MSL).
(See FLIGHT LEVEL.)
a.MSL Altitude − Altitude expressed in feet
measured from mean sea level.
b.AGL Altitude − Altitude expressed in feet
measured above ground level.
c.Indicated Altitude− The altitude as shown by an
altimeter. On a pressure or barometric altimeter it isaltitude as shown uncorrected for instrument errorand uncompensated for variation from standardatmospheric conditions.
(See ICAO term ALTITUDE.)
ALTITUDE [ICAO]− The vertical distance of a level,
a point or an object considered as a point, measuredfrom mean sea level (MSL).
ALTITUDE READOUT − An aircraft’s altitude,
transmitted via the Mode C transponder feature, thatis visually displayed in 100-foot increments on a
radar scope having readout capability.
(See ALPHANUMERIC DISPLAY.)
(See AUTOMATED RADAR TERMINAL
SYSTEMS.)
(Refer to AIM.)
ALTITUDE RESERV ATION (ALTRV) − Airspace
utilization under prescribed conditions normally
employed for the mass movement of aircraft or other
special user requirements which cannot otherwise beaccomplished. ALTRVs are approved by theappropriate FAA facility.
(See AIR TRAFFIC CONTROL SYSTEM
COMMAND CENTER.)
ALTITUDE RESTRICTION − An altitude or alti-
tudes, stated in the order flown, which are to bemaintained until reaching a specific point or time.Altitude restrictions may be issued by ATC due totraffic, terrain, or other airspace considerations.
ALTITUDE RESTRICTIONS ARE CANCELED −
Adherence to previously imposed altitude restric-tions is no longer required during a climb or descent.
ALTRV−
(See ALTITUDE RESERVATION.)
AMVER−
(See AUTOMATED MUTUAL-ASSISTANCE
VESSEL RESCUE SYSTEM.)
APB−
(See AUTOMATED PROBLEM DETECTION
BOUNDARY.)
APD−
(See AUTOMATED PROBLEM DETECTION.)
APDIA−
(See AUTOMATED PROBLEM DETECTION
INHIBITED AREA.)
APPROACH CLEARANCE − Authorization by
ATC for a pilot to conduct an instrument approach.The type of instrument approach for which aclearance and other pertinent information is provided
in the approach clearance when required.
(See CLEARED APPROACH.)
(See INSTRUMENT APPROACH
PROCEDURE.)
(Refer to AIM.)
(Refer to 14 CFR Part 91.)
Pilot/Controller Glossary10/12/17
PCG A−11APPROACH CONTROL FACILITY − A terminal
ATC facility that provides approach control service ina terminal area.
(See APPROACH CONTROL SERVICE.)
(See RADAR APPROACH CONTROL
FACILITY.)
APPROACH CONTROL SERVICE − Air traffic
control service provided by an approach controlfacility for arriving and departing VFR/IFR aircraftand, on occasion, en route aircraft. At some airportsnot served by an approach control facility, theARTCC provides limited approach control service.
(See ICAO term APPROACH CONTROL
SERVICE.)
(Refer to AIM.)
APPROACH CONTROL SERVICE [ICAO] − Air
traffic control service for arriving or departingcontrolled flights.
APPROACH GATE − An imaginary point used
within ATC as a basis for vectoring aircraft to thefinal approach course. The gate will be establishedalong the final approach course 1 mile from the final
approach fix on the side away from the airport andwill be no closer than 5 miles from the landingthreshold.
APPROACH HOLD AREA − The locations on
taxiways in the approach or departure areas of arunway designated to protect landing or departingaircraft. These locations are identified by signs andmarkings.
APPROACH LIGHT SYSTEM −
(See AIRPORT LIGHTING.)
APPROACH SEQUENCE − The order in which
aircraft are positioned while on approach or awaiting
approach clearance.
(See LANDING SEQUENCE.)
(See ICAO term APPROACH SEQUENCE.)
APPROACH SEQUENCE [ICAO] − The order in
which two or more aircraft are cleared to approach to
land at the aerodrome.
APPROACH SPEED − The recommended speed
contained in aircraft manuals used by pilots whenmaking an approach to landing. This speed will vary
for different segments of an approach as well as foraircraft weight and configuration.APPROACH WITH VERTICAL GUIDANCE
(APV)– A term used to describe RNA V approachprocedures that provide lateral and vertical guidance
but do not meet the requirements to be considered aprecision approach.
APPROPRIATE ATS AUTHORITY [ICAO] − The
relevant authority designated by the State responsible
for providing air traffic services in the airspaceconcerned. In the United States, the “appropriate ATS
authority” is the Program Director for Air TrafficPlanning and Procedures, ATP-1.
APPROPRIATE AUTHORITY −
a.Regarding flight over the high seas: the relevant
authority is the State of Registry.
b.Regarding flight over other than the high seas:
the relevant authority is the State having sovereigntyover the territory being overflown.
APPROPRIATE OBSTACLE CLEARANCE
MINIMUM AL TITUDE− Any of the following:
(See MINIMUM EN ROUTE IFR ALTITUDE.)
(See MINIMUM IFR ALTITUDE.)
(See MINIMUM OBSTRUCTION CLEARANCE
ALTITUDE.)
(See MINIMUM VECTORING ALTITUDE.)
APPROPRIATE TERRAIN CLEARANCE
MINIMUM AL TITUDE− Any of the following:
(See MINIMUM EN ROUTE IFR ALTITUDE.)
(See MINIMUM IFR ALTITUDE.)
(See MINIMUM OBSTRUCTION CLEARANCE
ALTITUDE.)
(See MINIMUM VECTORING ALTITUDE.)
APRON− A defined area on an airport or heliport
intended to accommodate aircraft for purposes ofloading or unloading passengers or cargo, refueling,parking, or maintenance. With regard to seaplanes, a
ramp is used for access to the apron from the water.
(See ICAO term APRON.)
APRON [ICAO] − A defined area, on a land
aerodrome, intended to accommodate aircraft forpurposes of loading or unloading passengers, mail or
cargo, refueling, parking or maintenance.
ARC− The track over the ground of an aircraft flying
at a constant distance from a navigational aid byreference to distance measuring equipment (DME).
AREA CONTROL CENTER [ICAO] − An air traffic
control facility primarily responsible for ATCservices being provided IFR aircraft during the en
Pilot/Controller Glossary 10/12/17
PCG A−12route phase of flight. The U.S. equivalent facility is
an air route traffic control center (ARTCC).
AREA NA VIGATION (RNA V) − A method of
navigation which permits aircraft operation on anydesired flight path within the coverage of ground − or
space−based navigation aids or within the limits of
the capability of self-contained aids, or a combination
of these.
Note: Area navigation includes
performance −based navigation as well as other
operations that do not meet the definition of
performance −based navigation.
AREA NA VIGATION (RNA V) APPROACH
CONFIGURATION:
a.STANDARD T − An RNA V approach whose
design allows direct flight to any one of three initialapproach fixes (IAF) and eliminates the need forprocedure turns. The standard design is to align theprocedure on the extended centerline with the missed
approach point (MAP) at the runway threshold, thefinal approach fix (FAF), and the initial approach/intermediate fix (IAF/IF). The other two IAFs will be
established perpendicular to the IF.
b.MODIFIED T − An RNA V approach design for
single or multiple runways where terrain oroperational constraints do not allow for the standardT. The “T” may be modified by increasing ordecreasing the angle from the corner IAF(s) to the IF
or by eliminating one or both corner IAFs.
c.STANDARD I − An RNA V approach design for
a single runway with both corner IAFs eliminated.Course reversal or radar vectoring may be required at
busy terminals with multiple runways.
d.TERMINAL ARRIV AL AREA (TAA) − The
TAA is controlled airspace established in conjunctionwith the Standard or Modified T and I RNA Vapproach configurations. In the standard TAA, thereare three areas: straight-in, left base, and right base.The arc boundaries of the three areas of the TAA arepublished portions of the approach and allow aircraft
to transition from the en route structure direct to thenearest IAF. TAAs will also eliminate or reduce
feeder routes, departure extensions, and procedure
turns or course reversal.
1.STRAIGHT-IN AREA − A 30NM arc
centered on the IF bounded by a straight lineextending through the IF perpendicular to theintermediate course.2.LEFT BASE AREA − A 30NM arc centered
on the right corner IAF. The area shares a boundarywith the straight-in area except that it extends out for
30NM from the IAF and is bounded on the other sideby a line extending from the IF through the FAF to thearc.
3.RIGHT BASE AREA − A 30NM arc centered
on the left corner IAF. The area shares a boundarywith the straight-in area except that it extends out for
30NM from the IAF and is bounded on the other sideby a line extending from the IF through the FAF to thearc.
AREA NA VIGATION (RNA V) GLOBAL
POSITIONING SYSTEM (GPS) PRECISIONRUNW AY MONITORING (PRM) APPROACH– A GPS approach, which requires vertical guidance,used in lieu of an ILS PRM approach to conductapproaches to parallel runways whose extendedcenterlines are separated by less than 4,300 feet andat least 3,000 feet, where simultaneous close parallelapproaches are permitted. Also used in lieu of an ILSPRM and/or LDA PRM approach to conductSimultaneous Offset Instrument Approach (SOIA)operations.
ARINC− An acronym for Aeronautical Radio, Inc.,
a corporation largely owned by a group of airlines.ARINC is licensed by the FCC as an aeronauticalstation and contracted by the FAA to providecommunications support for air traffic control andmeteorological services in portions of internationalairspace.
ARMY A VIATION FLIGHT INFORMATION
BULLETIN − A bulletin that provides air operation
data covering Army, National Guard, and ArmyReserve aviation activities.
ARO−
(See AIRPORT RESERVATION OFFICE.)
ARRESTING SYSTEM − A safety device consisting
of two major components, namely, engaging orcatching devices and energy absorption devices forthe purpose of arresting both tailhook and/ornontailhook-equipped aircraft. It is used to preventaircraft from overrunning runways when the aircraftcannot be stopped after landing or during abortedtakeoff. Arresting systems have various names; e.g.,arresting gear, hook device, wire barrier cable.
(See ABORT.)
(Refer to AIM.)
Pilot/Controller Glossary10/12/17
PCG A−13ARRIVAL AIRCRAFT INTERV AL − An internally
generated program in hundredths of minutes basedupon the AAR. AAI is the desired optimum intervalbetween successive arrival aircraft over the vertex.
ARRIVAL CENTER − The ARTCC having jurisdic-
tion for the impacted airport.
ARRIVAL DELAY − A parameter which specifies a
period of time in which no aircraft will be metered for
arrival at the specified airport.
ARRIVAL SECTOR − An operational control sector
containing one or more meter fixes.
ARRIV AL SECTOR ADVISORY LIST − An
ordered list of data on arrivals displayed at thePVD/MDM of the sector which controls the meterfix.
ARRIVAL SEQUENCING PROGRAM − The auto-
mated program designed to assist in sequencingaircraft destined for the same airport.
ARRIVAL TIME− The time an aircraft touches down
on arrival.
ARSR−
(See AIR ROUTE SURVEILLANCE RADAR.)
ARTCC−
(See AIR ROUTE TRAFFIC CONTROL
CENTER.)
ARTS−
(See AUTOMATED RADAR TERMINAL
SYSTEMS.)
ASDA−
(See ACCELERATE-STOP DISTANCE
AVAILABLE.)
ASDA [ICAO] −
(See ICAO Term ACCELERATE-STOP
DISTANCE AVAILABLE.)
ASDE−
(See AIRPORT SURFACE DETECTION
EQUIPMENT.)
ASF−
(See AIRPORT STREAM FILTER.)
ASLAR−
(See AIRCRAFT SURGE LAUNCH AND
RECOVERY.)
ASP−
(See ARRIVAL SEQUENCING PROGRAM.)ASR−
(See AIRPORT SURVEILLANCE RADAR.)
ASR APPROACH −
(See SURVEILLANCE APPROACH.)
ASSOCIATED − A radar target displaying a data
block with flight identification and altitudeinformation.
(See UNASSOCIATED.)
ATC−
(See AIR TRAFFIC CONTROL.)
ATC ADVISES − Used to prefix a message of
noncontrol information when it is relayed to anaircraft by other than an air traffic controller.
(See ADVISORY.)
ATC ASSIGNED AIRSPACE − Airspace of defined
vertical/lateral limits, assigned by ATC, for thepurpose of providing air traffic segregation betweenthe specified activities being conducted within theassigned airspace and other IFR air traffic.
(See SPECIAL USE AIRSPACE.)
ATC CLEARANCE −
(See AIR TRAFFIC CLEARANCE.)
ATC CLEARS − Used to prefix an ATC clearance
when it is relayed to an aircraft by other than an airtraffic controller.
ATC INSTRUCTIONS − Directives issued by air
traffic control for the purpose of requiring a pilot totake specific actions; e.g., “Turn left heading two five
zero,” “Go around,” “Clear the runway.”
(Refer to 14 CFR Part 91.)
ATC PREFERRED ROUTE NOTIFICATION −
EDST notification to the appropriate controller of the
need to determine if an ATC preferred route needs to
be applied, based on destination airport.
(See ROUTE ACTION NOTIFICATION.)
(See EN ROUTE DECISION SUPPORT TOOL.)
ATC PREFERRED ROUTES − Preferred routes that
are not automatically applied by Host.
ATC REQUESTS − Used to prefix an ATC request
when it is relayed to an aircraft by other than an airtraffic controller.
ATC SECURITY SERVICES − Communications
and security tracking provided by an ATC facility insupport of the DHS, the DOD, or other Federalsecurity elements in the interest of national security.Such security services are only applicable within
Pilot/Controller Glossary 10/12/17
PCG A−14designated areas. ATC security services do not
include ATC basic radar services or flight following.
ATC SECURITY SERVICES POSITION − The
position responsible for providing ATC securityservices as defined. This position does not provideATC, IFR separation, or VFR flight followingservices, but is responsible for providing securityservices in an area comprising airspace assigned toone or more ATC operating sectors. This positionmay be combined with control positions.
ATC SECURITY TRACKING − The continuous
tracking of aircraft movement by an ATC facility insupport of the DHS, the DOD, or other securityelements for national security using radar (i.e., radar
tracking) or other means (e.g., manual tracking)without providing basic radar services (includingtraffic advisories) or other ATC services not definedin this section.
ATS SURVEILLANCE SERVICE [ICAO]– A term
used to indicate a service provided directly by means
of an ATS surveillance system.
ATC SURVEILLANCE SOURCE– Used by ATC
for establishing identification, control and separationusing a target depicted on an air traffic controlfacility’s video display that has met the relevantsafety standards for operational use and receivedfrom one, or a combination, of the followingsurveillance sources:a. Radar (See RADAR.)b. ADS-B (See AUTOMATIC DEPENDENTSURVEILLANCE −BROADCAST.)
c. W AM (See W IDE AREA MUL TILATERATION.)
(See INTERROGATOR.)
(See TRANSPONDER.)
(See ICAO term RADAR.)
(Refer to AIM.)
ATS SURVEILLANCE SYSTEM [ICAO]– A
generic term meaning variously, ADS −B, PSR, SSR
or any comparable ground −based system that enables
the identification of aircraft.
Note: A comparable ground −based system is one
that has been demonstrated, by comparative
assessment or other methodology, to have a level
of safety and performance equal to or better thanmonopulse SSR.
ATCAA−
(See ATC ASSIGNED AIRSPACE.)ATCRBS −
(See RADAR.)
ATCSCC −
(See AIR TRAFFIC CONTROL SYSTEM
COMMAND CENTER.)
ATCT−
(See TOWER.)
ATD−
(See ALONG −TRACK DISTANCE.)
ATIS−
(See AUTOMATIC TERMINAL INFORMATION
SERVICE.)
ATIS [ICAO] −
(See ICAO Term AUTOMATIC TERMINAL
INFORMATION SERVICE.)
ATS ROUTE [ICAO] − A specified route designed for
channeling the flow of traffic as necessary for theprovision of air traffic services.
Note: The term “ATS Route” is used to mean
variously, airway, advisory route, controlled oruncontrolled route, arrival or departure, etc.
ATTENTION ALL USERS PAGE (AAUP)- The
AAUP provides the pilot with additional information
relative to conducting a specific operation, forexample, PRM approaches and RNA V departures.
AUTOLAND APPROACH −An autoland system
aids by providing control of aircraft systems duringa precision instrument approach to at least decisionaltitude and possibly all the way to touchdown, aswell as in some cases, through the landing rollout.The autoland system is a sub-system of the autopilotsystem from which control surface managementoccurs. The aircraft autopilot sends instructions to the
autoland system and monitors the autoland systemperformance and integrity during its execution.
AUTOMATED INFORMATION TRANSFER
(AIT)− A precoordinated process, specifically
defined in facility directives, during which a transfer
of altitude control and/or radar identification isaccomplished without verbal coordination betweencontrollers using information communicated in a full
data block.
AUTOMATED MUTUAL-ASSISTANCE VESSEL
RESCUE SYSTEM − A facility which can deliver, in
a matter of minutes, a surface picture (SURPIC) ofvessels in the area of a potential or actual search and
Pilot/Controller Glossary10/12/17
PCG A−15rescue incident, including their predicted positions
and their characteristics.
(See FAA Order JO 7110.65, Para 10 −6−4,
INFLIGHT CONTINGENCIES.)
AUTOMATED PROBLEM DETECTION (APD) −
An Automation Processing capability that comparestrajectories in order to predict conflicts.
AUTOMATED PROBLEM DETECTION
BOUNDARY (APB) − The adapted distance beyond
a facilities boundary defining the airspace withinwhich EDST performs conflict detection.
(See EN ROUTE DECISION SUPPORT TOOL.)
AUTOMATED PROBLEM DETECTION INHIB-ITED AREA (APDIA) − Airspace surrounding a
terminal area within which APD is inhibited for allflights within that airspace.
AUTOMATED RADAR TERMINAL SYSTEMS
(ARTS)− A generic term for several tracking systems
included in the Terminal Automation Systems (TAS).
ARTS plus a suffix roman numeral denotes a majormodification to that system.
a.ARTS IIIA. The Radar Tracking and Beacon
Tracking Level (R T&BTL) of the modular, program-
mable automated radar terminal system. ARTS IIIAdetects, tracks, and predicts primary as well assecondary radar-derived aircraft targets. This moresophisticated computer-driven system upgrades theexisting ARTS III system by providing improvedtracking, continuous data recording, and fail-softcapabilities.
b.Common ARTS. Includes ARTS IIE, ARTS
IIIE; and ARTS IIIE with ACD (see DTAS) whichcombines functionalities of the previous ARTSsystems.
AUTOMATED WEATHER SYSTEM − Any of the
automated weather sensor platforms that collectweather data at airports and disseminate the weatherinformation via radio and/or landline. The systemscurrently consist of the Automated Surface Observ-ing System (ASOS), Automated Weather SensorSystem (AWSS) and Automated Weather Observa-tion System (AWOS).
AUTOMATED UNICOM − Provides completely
automated weather, radio check capability and airport
advisory information on an Automated UNICOMsystem. These systems offer a variety of features,typically selectable by microphone clicks, on theUNICOM frequency. Availability will be published
in the Chart Supplement U.S. and approach charts.
AUTOMATIC ALTITUDE REPORT −
(See ALTITUDE READOUT.)
AUTOMATIC ALTITUDE REPORTING − That
function of a transponder which responds to Mode C
interrogations by transmitting the aircraft’s altitudein 100-foot increments.
AUTOMATIC CARRIER LANDING SYSTEM −
U.S. Navy final approach equipment consisting ofprecision tracking radar coupled to a computer datalink to provide continuous information to the aircraft,
monitoring capability to the pilot, and a backupapproach system.
AUTOMATIC DEPENDENT SURVEILLANCE
(ADS) [ICAO] − A surveillance technique in which
aircraft automatically provide, via a data link, dataderived from on −board navigation and position
fixing systems, including aircraft identification, four
dimensional position and additional data asappropriate.
AUTOMATIC DEPENDENT SUR VEILLANCE −
BROADCAST (ADS-B) − A surveillance system in
which an aircraft or vehicle to be detected is fittedwith cooperative equipment in the form of a data link
transmitter. The aircraft or vehicle periodicallybroadcasts its GPS −derived position and other
information such as velocity over the data link, which
is received by a ground −based transmitter/receiver
(transceiver) for processing and display at an airtraffic control facility.
(See GLOBAL POSITIONING SYSTEM.)
(See GROUND −BASED TRANSCEIVER.)
AUTOMATIC DEPENDENT SUR VEILLANCE −
CONTRACT (ADS −C)− A data link position
reporting system, controlled by a ground station, that
establishes contracts with an aircraft’s avionics thatoccur automatically whenever specific events occur,or specific time intervals are reached.
AUTOMATIC DEPENDENT SURVEILLANCE-
REBROADCAST (ADS-R) − A datalink translation
function of the ADS −B ground system required to
accommodate the two separate operating frequencies
(978 MHz and 1090 MHz). The ADS −B system
receives the ADS −B messages transmitted on one
frequency and ADS −R translates and reformats the
information for rebroadcast and use on the otherfrequency. This allows ADS −B In equipped aircraft
Pilot/Controller Glossary 10/12/17
PCG A−16to see nearby ADS −B Out traffic regardless of the
operating link of the other aircraft. Aircraft operating
on the same ADS −B frequency exchange information
directly and do not require the ADS −R translation
function.
AUTOMATIC DIRECTION FINDER − An aircraft
radio navigation system which senses and indicatesthe direction to a L/MF nondirectional radio beacon(NDB) ground transmitter. Direction is indicated tothe pilot as a magnetic bearing or as a relative bearingto the longitudinal axis of the aircraft depending onthe type of indicator installed in the aircraft. In certainapplications, such as military, ADF operations maybe based on airborne and ground transmitters in theVHF/UHF frequency spectrum.
(See BEARING.)
(See NONDIRECTIONAL BEACON.)
AUTOMATIC FLIGHT INFORMATION SER-
VICE (AFIS) − ALASKA FSSs ONLY − The
continuous broadcast of recorded non −control
information at airports in Alaska where a FSSprovides local airport advisory service. The AFISbroadcast automates the repetitive transmission ofessential but routine information such as weather,wind, altimeter, favored runway, braking action,airport NOTAMs, and other applicable information.The information is continuously broadcast over adiscrete VHF radio frequency (usually the ASOS/AWSS/AWOS frequency).
AUTOMATIC TERMINAL INFORMATION SER-
VICE− The continuous broadcast of recorded
noncontrol information in selected terminal areas. Its
purpose is to improve controller effectiveness and to
relieve frequency congestion by automating therepetitive transmission of essential but routineinformation; e.g., “Los Angeles information Alfa.One three zero zero Coordinated Universal Time.Weather, measured ceiling two thousand overcast,visibility three, haze, smoke, temperature seven one,
dew point five seven, wind two five zero at five,altimeter two niner niner six. I-L-S Runway T wo FiveLeft approach in use, Runway Two Five Right closed,
advise you have Alfa.”
(See ICAO term AUTOMATIC TERMINAL
INFORMATION SERVICE.)
(Refer to AIM.)
AUTOMATIC TERMINAL INFORMATION SER-
VICE [ICAO] − The provision of current, routine
information to arriving and departing aircraft bymeans of continuous and repetitive broadcaststhroughout the day or a specified portion of the day.
AUTOROTA TION− A rotorcraft flight condition in
which the lifting rotor is driven entirely by action ofthe air when the rotorcraft is in motion.
a.Autorotative Landing/Touchdown Autorota-
tion. Used by a pilot to indicate that the landing willbe made without applying power to the rotor.
b.Low Level Autorotation. Commences at an
altitude well below the traffic pattern, usually below100 feet AGL and is used primarily for tacticalmilitary training.
c.180 degrees Autorotation. Initiated from a
downwind heading and is commenced well inside the
normal traffic pattern. “Go around” may not bepossible during the latter part of this maneuver.
A V AILABLE LANDING DISTANCE (ALD) − The
portion of a runway available for landing and roll-out
for aircraft cleared for LAHSO. This distance ismeasured from the landing threshold to thehold-short point.
A VIATION WEATHER SERVICE − A service
provided by the National W eather Service (NWS) and
FAA which collects and disseminates pertinentweather information for pilots, aircraft operators, and
ATC. Available aviation weather reports andforecasts are displayed at each NWS office and FAA
FSS.
(See TRANSCRIBED WEATHER BROADCAST.)
(See WEATHER ADVISORY.)(Refer to AIM.)
AWW−
(See SEVERE WEATHER FORECAST
ALERTS.)
Pilot/Controller Glossary10/12/17
PCG B−1B
BACK-TAXI − A term used by air traffic controllers
to taxi an aircraft on the runway opposite to the traffic
flow. The aircraft may be instructed to back-taxi tothe beginning of the runway or at some point beforereaching the runway end for the purpose of departure
or to exit the runway.
BASE LEG −
(See TRAFFIC PATTERN.)
BEACON −
(See AERONAUTICAL BEACON.)
(See AIRPORT ROTATING BEACON.)(See AIRWAY BEACON.)
(See MARKER BEACON.)
(See NONDIRECTIONAL BEACON.)
(See RADAR.)
BEARING − The horizontal direction to or from any
point, usually measured clockwise from true north,magnetic north, or some other reference pointthrough 360 degrees.
(See NONDIRECTIONAL BEACON.)
BELOW MINIMUMS − Weather conditions below
the minimums prescribed by regulation for theparticular action involved; e.g., landing minimums,takeoff minimums.
BLAST FENCE − A barrier that is used to divert or
dissipate jet or propeller blast.
BLAST PAD − A surface adjacent to the ends of a
runway provided to reduce the erosive effect of jetblast and propeller wash.
BLIND SPEED − The rate of departure or closing of
a target relative to the radar antenna at whichcancellation of the primary radar target by movingtarget indicator (MTI) circuits in the radar equipmentcauses a reduction or complete loss of signal.
(See ICAO term BLIND VELOCITY.)
BLIND SPOT − An area from which radio
transmissions and/or radar echoes cannot bereceived. The term is also used to describe portionsof the airport not visible from the control tower.
BLIND TRANSMISSION −
(See TRANSMITTING IN THE BLIND.)BLIND VELOCITY [ICAO] − The radial velocity of
a moving target such that the target is not seen onprimary radars fitted with certain forms of fixed echo
suppression.
BLIND ZONE−
(See BLIND SPOT.)
BLOCKED − Phraseology used to indicate that a
radio transmission has been distorted or interrupteddue to multiple simultaneous radio transmissions.
BOTTOM ALTITUDE– In reference to published
altitude restrictions on a STAR or STAR runwaytransition, the lowest altitude authorized.
BOUNDARY LIGHTS
−
(See AIRPORT LIGHTING.)
BRAKING ACTION (GOOD, GOOD TO MEDI-
UM, MEDIUM, MEDIUM TO POOR, POOR, ORNIL)− A report of conditions on the airport
movement area providing a pilot with a degree/quali-
ty of braking to expect. Braking action is reported in
terms of good, good to medium, medium, medium to
poor, poor, or nil.
(See RUNWAY CONDITION READING.)
(See RUNWAY CONDITION REPORT.)
(See RUNWAY CONDITION CODES.)
BRAKING ACTION ADVISORIES − When tower
controllers receive runway braking action reportswhich include the terms “medium,” “poor,” or “nil,”
or whenever weather conditions are conducive todeteriorating or rapidly changing runway brakingconditions, the tower will include on the ATISbroadcast the statement, “Braking Action Advisories
are in Effect.” During the time braking action
advisories are in effect, ATC will issue the most
current braking action report for the runway in use to
each arriving and departing aircraft. Pilots should be
prepared for deteriorating braking conditions andshould request current runway condition information
if not issued by controllers. Pilots should also be
prepared to provide a descriptive runway conditionreport to controllers after landing.
BREAKOUT − A technique to direct aircraft out of
the approach stream. In the context of simultaneous(independent) parallel operations, a breakout is usedto direct threatened aircraft away from a deviatingaircraft.
Pilot/Controller Glossary 10/12/17
PCG B−2BROADCAST − Transmission of information for
which an acknowledgement is not expected.
(See ICAO term BROADCAST.)
BROADCAST [ICAO]− A transmission of informa-
tion relating to air navigation that is not addressed toa specific station or stations.BUFFER AREA − As applied to an MV A or MIA
chart, a depicted three (3) or five (5) NM radiusMV A/MIA sector isolating a displayed obstacle forwhich the sector is established. A portion of a bufferarea can also be inclusive of a MV A/MIA sectorpolygon boundary.
Pilot/Controller Glossary10/12/17
PCG C−1C
CALCULATED LANDING TIME − A term that may
be used in place of tentative or actual calculatedlanding time, whichever applies.
CALL FOR RELEASE − Wherein the overlying
ARTCC requires a terminal facility to initiate verbal
coordination to secure ARTCC approval for releaseof a departure into the en route environment.
CALL UP − Initial voice contact between a facility
and an aircraft, using the identification of the unitbeing called and the unit initiating the call.
(Refer to AIM.)
CANADIAN MINIMUM NA VIGATION PERFOR-
MANCE SPECIFICATION AIRSPACE − That
portion of Canadian domestic airspace within whichMNPS separation may be applied.
CARDINAL ALTITUDES − “Odd” or “Even”
thousand-foot altitudes or flight levels; e.g., 5,000,6,000, 7,000, FL 250, FL 260, FL 270.
(See ALTITUDE.)
(See FLIGHT LEVEL.)
CARDINAL FLIGHT LEVELS −
(See CARDINAL ALTITUDES.)
CAT−
(See CLEAR-AIR TURBULENCE.)
CATCH POINT − A fix/waypoint that serves as a
transition point from the high altitude waypointnavigation structure to an arrival procedure (STAR)or the low altitude ground −based navigation
structure.
CEILING − The heights above the earth’s surface of
the lowest layer of clouds or obscuring phenomenathat is reported as “broken,” “overcast,” or“obscuration,” and not classified as “thin” or“partial.”
(See ICAO term CEILING.)
CEILING [ICAO] − The height above the ground or
water of the base of the lowest layer of cloud below6,000 meters (20,000 feet) covering more than halfthe sky.
CENRAP −
(See CENTER RADAR ARTS
PRESENTATION/PROCESSING.)CENRAP-PLUS −
(See CENTER RADAR ARTS
PRESENTATION/PROCESSING-PLUS.)
CENTER −
(See AIR ROUTE TRAFFIC CONTROL
CENTER.)
CENTER’S AREA − The specified airspace within
which an air route traffic control center (ARTCC)provides air traffic control and advisory service.
(See AIR ROUTE TRAFFIC CONTROL
CENTER.)
(Refer to AIM.)
CENTER RADAR ARTS PRESENTATION/
PROCESSING − A computer program developed to
provide a back-up system for airport surveillanceradar in the event of a failure or malfunction. Theprogram uses air route traffic control center radar for
the processing and presentation of data on the ARTSIIA or IIIA displays.
CENTER RADAR ARTS PRESENTATION/
PROCESSING-PLUS − A computer program
developed to provide a back-up system for airportsurveillance radar in the event of a terminal secondary
radar system failure. The program uses a combinationof Air Route Traffic Control Center Radar andterminal airport surveillance radar primary targetsdisplayed simultaneously for the processing andpresentation of data on the ARTS IIA or IIIAdisplays.
CENTER TRACON AUTOMATION SYSTEM
(CTAS)− A computerized set of programs designed
to aid Air Route Traffic Control Centers andTRACONs in the management and control of airtraffic.
CENTER WEATHER ADVISORY − An unsched-
uled weather advisory issued by Center WeatherService Unit meteorologists for ATC use to alertpilots of existing or anticipated adverse weatherconditions within the next 2 hours. A CWA maymodify or redefine a SIGMET.
(See AWW.)
(See AIRMET.)(See CONVECTIVE SIGMET.)(See SIGMET.)
(Refer to AIM.)
Pilot/Controller Glossary 10/12/17
PCG C−2CENTRAL EAST PACIFIC− An organized route
system between the U.S. West Coast and Hawaii.
CEP−
(See CENTRAL EAST PACIFIC.)
CERAP−
(See COMBINED CENTER-RAPCON.)
CERTIFIED TOWER RADAR DISPLAY (CTRD)−
An FAA radar display certified for use in the NAS.
CFR−
(See CALL FOR RELEASE.)
CHAFF− Thin, narrow metallic reflectors of various
lengths and frequency responses, used to reflect radar
energy. These reflectors, when dropped from aircraftand allowed to drift downward, result in lar ge targets
on the radar display.
CHART SUPPLEMENT U.S. − A publication
designed primarily as a pilot’s operational manualcontaining all airports, seaplane bases, and heliportsopen to the public including communications data,navigational facilities, and certain special notices and
procedures. This publication is issued in sevenvolumes according to geographical area.
CHARTED VFR FLYWAYS − Charted VFR Fly-
ways are flight paths recommended for use to bypass
areas heavily traversed by large turbine-poweredaircraft. Pilot compliance with recommendedflyways and associated altitudes is strictly voluntary.
VFR Flyway Planning charts are published on theback of existing VFR Terminal Area charts.
CHARTED VISUAL FLIGHT PROCEDURE
APPROACH − An approach conducted while
operating on an instrument flight rules (IFR) flightplan which authorizes the pilot of an aircraft toproceed visually and clear of clouds to the airport via
visual landmarks and other information depicted ona charted visual flight procedure. This approach mustbe authorized and under the control of the appropriate
air traffic control facility. Weather minimumsrequired are depicted on the chart.
CHASE− An aircraft flown in proximity to another
aircraft normally to observe its performance duringtraining or testing.
CHASE AIRCRAFT −
(See CHASE.)
CIRCLE-TO-LAND MANEUVER − A maneuver
initiated by the pilot to align the aircraft with arunway for landing when a straight-in landing from
an instrument approach is not possible or is notdesirable. At tower controlled airports, this maneuver
is made only after ATC authorization has beenobtained a nd the pilot has established required visual
reference to the airport.
(See CIRCLE TO RUNWAY.)
(See LANDING MINIMUMS.)(Refer to AIM.)
CIRCLE TO RUNWAY (RUNWAY NUMBER) −
Used by ATC to inform the pilot that he/she mustcircle to land because the runway in use is other than
the runway aligned with the instrument approachprocedure. When the direction of the circlingmaneuver in relation to the airport/runway isrequired, the controller will state the direction (eightcardinal compass points) and specify a left or rightdownwind or base leg as appropriate; e.g., “ClearedVOR Runway Three Six Approach circle to RunwayTwo Two,” or “Circle northwest of the airport for aright downwind to Runway Two Two.”
(See CIRCLE-TO-LAND MANEUVER.)
(See LANDING MINIMUMS.)(Refer to AIM.)
CIRCLING APPROACH −
(See CIRCLE-TO-LAND MANEUVER.)
CIRCLING MANEUVER −
(See CIRCLE-TO-LAND MANEUVER.)
CIRCLING MINIMA −
(See LANDING MINIMUMS.)
CLASS A AIRSPACE −
(See CONTROLLED AIRSPACE.)
CLASS B AIRSPACE −
(See CONTROLLED AIRSPACE.)
CLASS C AIRSPACE −
(See CONTROLLED AIRSPACE.)
CLASS D AIRSPACE −
(See CONTROLLED AIRSPACE.)
CLASS E AIRSPACE −
(See CONTROLLED AIRSPACE.)
CLASS G AIRSPACE − That airspace not designated
as Class A, B, C, D or E.
CLEAR AIR TURBULENCE (CAT) − Turbulence
encountered in air where no clouds are present. Thisterm is commonly applied to high-level turbulence
Pilot/Controller Glossary10/12/17
PCG C−3associated with wind shear. CA T is often encountered
in the vicinity of the jet stream.
(See WIND SHEAR.)
(See JET STREAM.)
CLEAR OF THE RUNWAY −
a.Taxiing aircraft, which is approaching a
runway, is clear of the runway when all parts of theaircraft are held short of the applicable runwayholding position marking.
b.A pilot or controller may consider an aircraft,
which is exiting or crossing a runway, to be clear ofthe runway when all parts of the aircraft are beyondthe runway edge and there are no restrictions to itscontinued movement beyond the applicable runwayholding position marking.
c.Pilots and controllers shall exercise good
judgement to ensure that adequate separation existsbetween all aircraft on runways and taxiways atairports with inadequate runway edge lines orholding position markings.
CLEARANCE −
(See AIR TRAFFIC CLEARANCE.)
CLEARANCE LIMIT− The fix, point, or location to
which an aircraft is cleared when issued an air traffic
clearance.
(See ICAO term CLEARANCE LIMIT.)
CLEARANCE LIMIT [ICAO] − The point to which
an aircraft is granted an air traffic control clearance.
CLEARANCE VOID IF NOT OFF BY (TIME) −
Used by ATC to advise an aircraft that the departureclearance is automatically canceled if takeoff is not
made prior to a specified time. The pilot must obtain
a new clearance or cancel his/her IFR flight plan if notoff by the specified time.
(See ICAO term CLEARANCE VOID TIME.)
CLEARANCE VOID TIME [ICAO] − A time
specified by an air traffic control unit at which aclearance ceases to be valid unless the aircraftconcerned has already taken action to complytherewith.
CLEARED APPROACH − ATC authorization for an
aircraft to execute any standard or special instrumentapproach procedure for that airport. Normally, anaircraft will be cleared for a specific instrument
approach procedure.
(See CLEARED (Type of) APPROACH.)
(See INSTRUMENT APPROACH
PROCEDURE.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
CLEARED (T ype of) APPROACH − ATC authoriza-
tion for an aircraft to execute a specific instrumentapproach procedure to an airport; e.g., “Cleared ILSRunway Three Six Approach.”
(See APPROACH CLEARANCE.)
(See INSTRUMENT APPROACH
PROCEDURE.)
(Refer to 14 CFR Part 91.)(Refer to AIM.)
CLEARED AS FILED− Means the aircraft is cleared
to proceed in accordance with the route of flight filedin the flight plan. This clearance does not include thealtitude, DP, or DP Transition.
(See REQUEST FULL ROUTE CLEARANCE.)
(Refer to AIM.)
CLEARED FOR TAKEOFF − ATC authorization
for an aircraft to depart. It is predicated on knowntraffic and known physical airport conditions.
CLEARED FOR THE OPTION − ATC authoriza-
tion for an aircraft to make a touch-and-go, lowapproach, missed approach, stop and go, or full stoplanding at the discretion of the pilot. It is normallyused in training so that an instructor can evaluate astudent’s performance under changing situations.Pilots should advise ATC if they decide to remain on
the runway, of any delay in their stop and go, delayclearing the runway, or are unable to comply with the
instruction(s).
(See OPTION APPROACH.)
(Refer to AIM.)
CLEARED THROUGH − ATC authorization for an
aircraft to make intermediate stops at specifiedairports without refiling a flight plan while en routeto the clearance limit.
CLEARED TO LAND − ATC authorization for an
aircraft to land. It is predicated on known traffic andknown physical airport conditions.
CLEARWAY − An area beyond the takeoff runway
under the control of airport authorities within whichterrain or fixed obstacles may not extend above
Pilot/Controller Glossary 10/12/17
PCG C−4specified limits. These areas may be required for
certain turbine-powered operations and the size andupward slope of the clearway will differ depending on
when the aircraft was certificated.
(Refer to 14 CFR Part 1.)
CLIMB TO VFR − ATC authorization for an aircraft
to climb to VFR conditions within Class B, C, D, andE surface areas when the only weather limitation isrestricted visibility. The aircraft must remain clear of
clouds while climbing to VFR.
(See SPECIAL VFR CONDITIONS.)
(Refer to AIM.)
CLIMBOUT − That portion of flight operation
between takeoff and the initial cruising altitude.
CLIMB VIA– An abbreviated ATC clearance that
requires compliance with the procedure lateral path,associated speed restrictions, and altitude restrictions
along the cleared route or procedure.
CLOSE PARALLEL RUNWAYS − Two parallel
runways whose extended centerlines are separated by
less than 4,300 feet and at least 3000 feet (750 feet forSOIA operations) for which ATC is authorized toconduct simultaneous independent approach opera-tions. PRM and simultaneous close parallel appear in
approach title. Dual communications, special pilottraining, an Attention All Users Page (AAUP), NTZmonitoring by displays that have aural and visualalerting algorithms are required. A high update ratesurveillance sensor is required for certain runway orapproach course spacing.
CLOSED RUNWAY − A runway that is unusable for
aircraft operations. Only the airport management/military operations office can close a runway.
CLOSED TRAFFIC − Successive operations involv-
ing takeoffs and landings or low approaches wherethe aircraft does not exit the traffic pattern.
CLOUD− A cloud is a visible accumulation of
minute water droplets and/or ice particles in theatmosphere above the Earth’s surface. Cloud differsfrom ground fog, fog, or ice fog only in that the latter
are, by definition, in contact with the Earth’s surface.
CLT−
(See CALCULATED LANDING TIME.)
CLUTTER − In radar operations, clutter refers to the
reception and visual display of radar returns causedby precipitation, chaff, terrain, numerous aircraft
targets, or other phenomena. Such returns may limitor preclude ATC from providing services based onradar.
(See CHAFF.)
(See GROUND CLUTTER.)
(See PRECIPITATION.)
(See TARGET.)
(See ICAO term RADAR CLUTTER.)
CMNPS−
(See CANADIAN MINIMUM NAVIGATION
PERFORMANCE SPECIFICATION AIRSPACE.)
COASTAL FIX − A navigation aid or intersection
where an aircraft transitions between the domesticroute structure and the oceanic route structure.
CODES− The number assigned to a particular
multiple pulse reply signal transmitted by atransponder.
(See DISCRETE CODE.)
COLD TEMPERATURE COMPENSATION − An
action on the part of the pilot to adjust an aircraft’sindicated altitude due to the effect of coldtemperatures on true altitude above terrain versusaircraft indicated altitude. The amount ofcompensation required increases at a greater rate with
a decrease in temperature and increase in heightabove the reporting station.
COLLABORATIVE TRAJECTORY OPTIONS
PROGRAM (CTOP)- CTOP is a traffic management
program administered by the Air Traffic ControlSystem Command Center (ATCSCC) that managesdemand through constrained airspace, while consid-ering operator preference with regard to both routeand delay as defined in a Trajectory Options Set(TOS).
COMBINED CENTER-RAPCON − An air traffic
facility which combines the functions of an ARTCCand a radar approach control facility.
(See AIR ROUTE TRAFFIC CONTROL
CENTER.)
(See RADAR APPROACH CONTROL
FACILITY.)
COMMON POINT − A significant point over which
two or more aircraft will report passing or havereported passing before proceeding on the same ordiverging tracks. To establish/maintain longitudinalseparation, a controller may determine a common
Pilot/Controller Glossary10/12/17
PCG C−5point not originally in the aircraft’s flight plan and
then clear the aircraft to fly over the point.
(See SIGNIFICANT POINT.)
COMMON POR TION−
(See COMMON ROUTE.)
COMMON ROUTE − That segment of a North
American Route between the inland navigationfacility and the coastal fix.
OR
COMMON ROUTE − Typically the portion of a
RNA V STAR between the en route transition endpoint and the runway transition start point; however,the common route may only consist of a single pointthat joins the en route and runway transitions.
COMMON TRAFFIC ADVISORY FREQUENCY
(CTAF)− A frequency designed for the purpose of
carrying out airport advisory practices whileoperating to or from an airport without an operatingcontrol tower. The CTAF may be a UNICOM,Multicom, FSS, or tower frequency and is identified
in appropriate aeronautical publications.
(See DESIGNATED COMMON TRAFFIC
ADVISORY FREQUENCY (CTAF) AREA.)
(Refer to AC 90-42, Traffic Advisory Practices at
Airports Without Operating Control Towers.)
COMPASS LOCATOR − A low power, low or
medium frequency (L/MF) radio beacon installed atthe site of the outer or middle marker of an instrumentlanding system (ILS). It can be used for navigation at
distances of approximately 15 miles or as authorized
in the approach procedure.
a.Outer Compass Locator (LOM) − A compass
locator installed at the site of the outer marker of aninstrument landing system.
(See OUTER MARKER.)
b.Middle Compass Locator (LMM) − A compass
locator installed at the site of the middle marker of an
instrument landing system.
(See MIDDLE MARKER.)
(See ICAO term LOCATOR.)
COMPASS ROSE − A circle, graduated in degrees,
printed on some charts or marked on the ground at an
airport. It is used as a reference to either true ormagnetic direction .
COMPLY WITH RESTRICTIONS − An ATC
instruction that requires an aircraft being vectoredback onto an arrival or departure procedure to complywith all altitude and/or speed restrictions depicted on
the procedure. This term may be used in lieu ofrepeating each remaining restriction that appears onthe procedure.
COMPOSITE FL IGHT PLAN − A flight plan which
specifies VFR operation for one portion of flight and
IFR for another portion. It is used primarily inmilitary operations.
(Refer to AIM.)
COMPOSITE ROUTE SYSTEM − An organized
oceanic route structure, incorporating reduced lateral
spacing between routes, in which compositeseparation is authorized.
COMPOSITE SEPARATION − A method of separat-
ing aircraft in a composite route system where, bymanagement of route and altitude assignments, acombination of half the lateral minimum specified for
the area concerned and half the vertical minimum isapplied.
COMPULSORY REPORTING POINTS − Reporting
points which must be reported to ATC. They aredesignated on aeronautical charts by solid triangles or
filed in a flight plan as fixes selected to define directroutes. These points are geographical locationswhich are defined by navigation aids/fixes. Pilotsshould discontinue position reporting over compul-sory reporting points when informed by ATC thattheir aircraft is in “radar contact.”
CONDITIONS NOT MONITORED − When an
airport operator cannot monitor the condition of themovement area or airfield surface area, thisinformation is issued as a NOTAM. Usuallynecessitated due to staffing, operating hours or other
mitigating factors associated with airport operations.
CONFIDENCE MANEUVER − A confidence man-
euver consists of one or more turns, a climb ordescent, or other maneuver to determine if the pilotin command (PIC) is able to receive and comply withATC instructions.
CONFLICT ALERT− A function of certain air traffic
control automated systems designed to alert radarcontrollers to existing or pending situations between
tracked targets (known IFR or VFR aircraft) thatrequire his/her immediate attention/action.
(See MODE C INTRUDER ALERT.)
CONFLICT RESOLUTION − The resolution of
potential conflictions between aircraft that are radaridentified and in communication with ATC by
Pilot/Controller Glossary 10/12/17
PCG C−6ensuring that radar targets do not touch. Pertinent
traffic advisories shall be issued when this procedure
is applied.
Note: This procedure shall not be provided utilizing
mosaic radar systems.
CONFORMANCE − The condition established when
an aircraft’s actual position is within the conformanceregion constructed around that aircraft at its position,
according to the trajectory associated with theaircraft’s Current Plan.
CONFORMANCE REGION − A volume, bounded
laterally, vertically, and longitudinally, within whichan aircraft must be at a given time in order to be inconformance with the Current Plan Trajectory for that
aircraft. At a given time, the conformance region isdetermined by the simultaneous application of thelateral, vertical, and longitudinal conformancebounds for the aircraft at the position defined by time
and aircraft’s trajectory.
CONSOLAN − A low frequency, long-distance
NA V AID used principally for transoceanic naviga-tions.
CONTACT −
a.Establish communication with (followed by the
name of the facility and, if appropriate, the frequency
to be used).
b.A flight condition wherein the pilot ascertains
the attitude of his/her aircraft and navigates by visualreference to the surface.
(See CONTACT APPROACH.)
(See RADAR CONTACT.)
CONTACT APPROACH − An approach wherein an
aircraft on an IFR flight plan, having an air trafficcontrol authorization, operating clear of clouds withat least 1 mile flight visibility and a reasonableexpectation of continuing to the destination airport in
those conditions, may deviate from the instrumentapproach procedure and proceed to the destinationairport by visual reference to the surface. Thisapproach will only be authorized when requested bythe pilot and the reported ground visibility at thedestination airport is at least 1 statute mile.
(Refer to AIM.)
CONTAMINATED RUNWAY − A runway is
considered contaminated whenever standing water,ice, snow, slush, frost in any form, heavy rubber, orother substances are present. A runway is contami-nated with respect to rubber deposits or other
friction-degrading substances when the averagefriction value for any 500-foot segment of the runway
within the ALD fails below the recommendedminimum friction level and the average friction value
in the adjacent 500-foot segments falls below themaintenance planning friction level.
CONTERMINOUS U.S. − The 48 adjoining States
and the District of Columbia.
CONTINENTAL UNITED STATES − The 49 States
located on the continent of North America and theDistrict of Columbia .
CONTINUE − When used as a control instruction
should be followed by another word or wordsclarifying what is expected of the pilot. Example:“continue taxi,” “continue descent,” “continueinbound,” etc.
CONTROL AREA [ICAO] − A controlled airspace
extending upwards from a specified limit above theearth.
CONTROL SECTOR − An airspace area of defined
horizontal and vertical dimensions for which acontroller or group of controllers has air trafficcontrol responsibility, normally within an air routetraffic control center or an approach control facility.Sectors are established based on predominant trafficflows, altitude strata, and controller workload. Pilotcommunications during operations within a sectorare normally maintained on discrete frequenciesassigned to the sector.
(See DISCRETE FREQUENCY.)
CONTROL SLASH − A radar beacon slash repre-
senting the actual position of the associated aircraft.Normally, the control slash is the one closest to theinterrogating radar beacon site. When ARTCC radaris operating in narrowband (digitized) mode, thecontrol slash is converted to a target symbol.
CONTROLLED AIRSPACE − An airspace of
defined dimensions within which air traffic controlservice is provided to IFR flights and to VFR flightsin accordance with the airspace classification.
a.Controlled airspace is a generic term that covers
Class A, Class B, Class C, Class D, and Class Eairspace.
b.Controlled airspace is also that airspace within
which all aircraft operators are subject to certain pilot
qualifications, operating rules, and equipmentrequirements in 14 CFR Part 91 (for specific
Pilot/Controller Glossary10/12/17
PCG C−7operating requirements, please refer to 14 CFR
Part 91). For IFR operations in any class of controlled
airspace, a pilot must file an IFR flight plan andreceive an appropriate ATC clearance. Each Class B,
Class C, and Class D airspace area designated for anairport contains at least one primary airport aroundwhich the airspace is designated (for specificdesignations and descriptions of the airspace classes,
please refer to 14 CFR Part 71).
c.Controlled airspace in the United States is
designated as follows:
1.CLASS A − Generally, that airspace from
18,000 feet MSL up to and including FL 600,including the airspace overlying the waters within 12
nautical miles of the coast of the 48 contiguous Statesand Alaska. Unless otherwise authorized, all personsmust operate their aircraft under IFR.
2.CLASS B − Generally, that airspace from the
surface to 10,000 feet MSL surrounding the nation’sbusiest airports in terms of airport operations orpassenger enplanements. The configuration of eachClass B airspace area is individually tailored andconsists of a surface area and two or more layers(some Class B airspace areas resemble upside-downwedding cakes), and is designed to contain allpublished instrument procedures once an aircraftenters the airspace. An ATC clearance is required for
all aircraft to operate in the area, and all aircraft thatare so cleared receive separation services within theairspace. The cloud clearance requirement for VFRoperations is “clear of clouds.”
3.CLASS C − Generally, that airspace from the
surface to 4,000 feet above the airport elevation(charted in MSL) surrounding those airports thathave an operational control tower, are serviced by aradar approach control, and that have a certainnumber of IFR operations or passenger enplane-ments. Although the configuration of each Class Carea is individually tailored, the airspace usuallyconsists of a surface area with a 5 nautical mile (NM)
radius, a circle with a 10NM radius that extends nolower than 1,200 feet up to 4,000 feet above theairport elevation, and an outer area that is not charted.
Each person must establish two-way radio commu-nications with the ATC facility providing air trafficservices prior to entering the airspace and thereaftermaintain those communications while within theairspace. VFR aircraft are only separated from IFRaircraft within the airspace.
(See OUTER AREA.)4.CLASS D − Generally, that airspace from the
surface to 2,500 feet above the airport elevation(charted in MSL) surrounding those airports thathave an operational control tower. The configurationof each Class D airspace area is individually tailoredand when instrument procedures are published, theairspace will normally be designed to contain theprocedures. Arrival extensions for instrumentapproach procedures may be Class D or Class Eairspace. Unless otherwise authorized, each personmust establish two-way radio communications withthe A TC facility providing air traffic services prior toentering the airspace and thereafter maintain thosecommunications while in the airspace. No separation
services are provided to VFR aircraft.
5.CLASS E − Generally, if the airspace is not
Class A, Class B, Class C, or Class D, and it iscontrolled airspace, it is Class E airspace. Class Eairspace extends upward from either the surface or adesignated altitude to the overlying or adj acent
controlled airspace. When designated as a surfacearea, the airspace will be configured to contain allinstrument procedures. Also in this class are Federal
airways, airspace beginning at either 700 or 1,200feet AGL used to transition to/from the terminal or en
route environment, en route domestic, and offshoreairspace areas designated below 18,000 feet MSL.Unless designated at a lower altitude, Class Eairspace begins at 14,500 MSL over the UnitedStates, including that airspace overlying the waterswithin 12 nautical miles of the coast of the 48contiguous States and Alaska, up to, but notincluding 18,000 feet MSL, and the airspace aboveFL 600.
CONTROLLED AIRSPACE [ICAO] − An airspace
of defined dimensions within which air traffic controlservice is provided to IFR flights and to VFR flightsin accordance with the airspace classification.
Note: Controlled airspace is a generic term which
covers ATS airspace Classes A, B, C, D, and E.
CONTROLLED TIME OF ARRIV AL − Arrival time
assigned during a Traf fic Management Program. This
time may be modified due to adjustments or useroptions.
CONTROLLER −
(See AIR TRAFFIC CONTROL SPECIALIST.)
CONTROLLER [ICAO] − A person authorized to
provide air traffic control services.
Pilot/Controller Glossary 10/12/17
PCG C−8CONTROLLER PILOT DATA LINK
COMMUNICATIONS (CPDLC) − A two−way
digital communications system that conveys textualair traffic control messages between controllers andpilots using ground or satellite-based radio relaystations.
CONVECTIVE SIGMET − A weather advisory
concerning convective weather significant to thesafety of all aircraft. Convective SIGMETs are issued
for tornadoes, lines of thunderstorms, embeddedthunderstorms of any intensity level, areas ofthunderstorms greater than or equal to VIP level 4with an area coverage of
4/10 (40%) or more, and hail
3/4 inch or greater.
(See AIRMET.)
(See AWW.)(See CWA.)
(See SIGMET.)
(Refer to AIM.)
CONVECTIVE SIGNIFICANT METEOROLOG-
ICAL INFORMA TION−
(See CONVECTIVE SIGMET.)
COORDINATES − The intersection of lines of
reference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determineposition or location.
COORDINATION FIX − The fix in relation to which
facilities will handoff, transfer control of an aircraft,or coordinate flight progress data. For terminalfacilities, it may also serve as a clearance for arriving
aircraft.
COPTER −
(See HELICOPTER.)
CORRECTION − An error has been made in the
transmission and the correct version follows.
COUPLED APPROACH − An instrument approach
performed by the aircraft autopilot, and/or visuallydepicted on the flight director, which is receivingposition in formation and/or steering commands from
onboard navigational equipment. In general, coupled
non-precision approaches must be flown manually(autopilot disengaged) at altitudes lower than 50 feet
AGL below the minimum descent altitude, andcoupled precision approaches must be flownmanually (autopilot disengaged) below 50 feet AGL
unless authorized to conduct autoland operations.Coupled instrument approaches are commonly flown
to the allowable IFR weather minima established bythe operator or PIC, or flown VFR for training andsafety.
COURSE −
a.The intended direction of flight in the horizontal
plane measured in degrees from north.
b.The ILS localizer signal pattern usually
specified as the front course or the back course.
(See BEARING.)
(See INSTRUMENT LANDING SYSTEM.)(See RADIAL.)
CPDLC−
(See CONTROLLER PILOT DATA LINK
COMMUNICATIONS.)
CPL [ICAO] −
(See ICAO term CURRENT FLIGHT PLAN.)
CRITICAL ENGINE − The engine which, upon
failure, would most adversely affect the performance
or handling qualities of an aircraft.
CROSS (FIX) AT (ALTITUDE) − Used by ATC
when a specific altitude restriction at a specified fixis required.
CROSS (FIX) AT OR ABOVE (AL TITUDE) − Used
by ATC when an altitude restriction at a specified fixis required. It does not prohibit the aircraft fromcrossing the fix at a higher altitude than specified;however, the higher altitude may not be one that will
violate a succeeding altitude restriction or altitudeassignment.
(See ALTITUDE RESTRICTION.)
(Refer to AIM.)
CROSS (FIX) AT OR BELOW (ALTITUDE) −
Used by ATC when a maximum crossing altitude ata specific fix is required. It does not prohibit theaircraft from crossing the fix at a lower altitude;however, it must be at or above the minimum IFRaltitude.
(See ALTITUDE RESTRICTION.)
(See MINIMUM IFR ALTITUDES.)(Refer to 14 CFR Part 91.)
CROSSWIND −
a.When used concerning the traffic pattern, the
word means “crosswind leg.”
(See TRAFFIC PATTERN.)
Pilot/Controller Glossary10/12/17
PCG C−9b.When used concerning wind conditions, the
word means a wind not parallel to the runway or thepath of an aircraft.
(See CROSSWIND COMPONENT.)
CROSSWIND COMPONENT − The wind compo-
nent measured in knots at 90 degrees to thelongitudinal axis of the runway.
CRUISE− Used in an ATC clearance to authorize a
pilot to conduct flight at any altitude from theminimum IFR altitude up to and including thealtitude specified in the clearance. The pilot maylevel off at any intermediate altitude within this block
of airspace. Climb/descent within the block is to bemade at the discretion of the pilot. However, once the
pilot starts descent and verbally reports leaving analtitude in the block, he/she may not return to thataltitude without additional ATC clearance. Further, it
is approval for the pilot to proceed to and make anapproach at destination airport and can be used inconjunction with:
a.An airport clearance limit at locations with a
standard/special instrument approach procedure. The
CFRs require that if an instrument letdown to anairport is necessary, the pilot shall make the letdownin accordance with a standard/special instrumentapproach procedure for that airport, or
b.An airport clearance limit at locations that are
within/below/outside controlled airspace and with-out a standard/special instrument approachprocedure. Such a clearance is NOT AUTHORIZA-TION for the pilot to descend under IFR conditionsbelow the applicable minimum IFR altitude nor does
it imply that ATC is exercising control over aircraftin Class G airspace; however, it provides a means forthe aircraft to proceed to destination airport, descend,and land in accordance with applicable CFRsgoverning VFR flight operations. Also, this provides
search and rescue protection until such time as theIFR flight plan is closed.
(See INSTRUMENT APPROACH
PROCEDURE.)
CRUISE CLIMB − A climb technique employed by
aircraft, usually at a constant power setting, resulting
in an increase of altitude as the aircraft weightdecreases.
CRUISING ALTITUDE − An altitude or flight level
maintained during en route level flight. This is aconstant altitude and should not be confused with a
cruise clearance.
(See ALTITUDE.)
(See ICAO term CRUISING LEVEL.)
CRUISING LEVEL −
(See CRUISING ALTITUDE.)
CRUISING LEVEL [ICAO] − A level maintained
during a significant portion of a flight.
CT MESSAGE − An EDCT time generated by the
ATCSCC to regulate traffic at arrival airports.Normally, a CT message is automatically transferred
from the traffic management system computer to theNAS en route computer and appears as an EDCT. Inthe event of a communication failure between thetraffic management system computer and the NAS,the CT message can be manually entered by the TMCat the en route facility.
CTA−
(See CONTROLLED TIME OF ARRIVAL.)
(See ICAO term CONTROL AREA.)
CTAF−
(See COMMON TRAFFIC ADVISORY
FREQUENCY.)
CTAS−
(See CENTER TRACON AUTOMATION
SYSTEM.)
CTOP−
(See COLLABORATIVE TRAJECTORY
OPTIONS PROGRAM)
CTRD−
(See CERTIFIED TOWER RADAR DISPLAY.)
CURRENT FLIGHT PLAN [ICAO] − The flight
plan, including changes, if any, brought about bysubsequent clearances.
CURRENT PLAN − The ATC clearance the aircraft
has received and is expected to fly.
CVFP APPROACH −
(See CHARTED VISUAL FLIGHT PROCEDURE
APPROACH.)
CWA−
(See CENTER WEATHER ADVISORY and
WEATHER ADVISORY.)
Pilot/Controller Glossary10/12/17
PCG D−1D
D-ATIS−
(See DIGITAL-AUTOMATIC TERMINAL
INFORMATION SERVICE.)
D−A TIS [ICAO] −
(See ICAO Term DATA LINK AUTOMATIC
TERMINAL INFORMATION SERVICE.)
DA [ICAO] −
(See ICAO Term DECISION
ALTITUDE/DECISION HEIGHT.)
DAIR−
(See DIRECT ALTITUDE AND IDENTITY
READOUT.)
DANGER AREA [ICAO] − An airspace of defined
dimensions within which activities dangerous to theflight of aircraft may exist at specified times.
Note: The term “Danger Area” is not used in
reference to areas within the United States or any
of its possessions or territories.
DAS−
(See DELAY ASSIGNMENT .)
DATA BLOCK −
(See ALPHANUMERIC DISPLAY.)
DATA LINK AUTOMATIC TERMINAL INFOR-
MATION SERVICE (D −ATIS) [ICAO] − The
provision of ATIS via data link.
DEAD RECKONING − Dead reckoning, as applied
to flying, is the navigation of an airplane solely bymeans of computations based on airspeed, course,heading, wind direction, and speed, groundspeed,and elapsed time.
DECISION ALTITUDE/DECISION HEIGHT
[ICAO Annex 6]- A specified altitude or height (A/H)
in the precision approach at which a missed approachmust be initiated if the required visual reference tocontinue the approach has not been established. 1. Decision altitude (DA) is referenced to mean sealevel and decision height (DH) is referenced to thethreshold elevation. 2. Category II and III minima are expressed as a DHand not a DA. Minima is assessed by reference to aradio altimeter and not a barometric altimeter, which
makes the minima a DH. 3. The required visual reference means that section of
the visual aids or of the approach area which shouldhave been in view for sufficient time for the pilot tohave made an assessment of the aircraft position andrate of change of position, in relation to the desiredflight path.
DECISION ALTITUDE (DA) − A specified altitude
(mean sea level (MSL)) on an instrument approachprocedure (ILS, GLS, vertically guided RNA V) atwhich the pilot must decide whether to continue theapproach or initiate an immediate missed approach if
the pilot does not see the required visual references.
DECISION HEIGHT (DH) − With respect to the
operation of aircraft, means the height at which adecision must be made during an ILS or PARinstrument approach to either continue the approachor to execute a missed approach.
(See ICAO term DECISION
ALTITUDE/DECISION HEIGHT.)
DECODER − The device used to decipher signals
received from ATCRBS transponders to effect theirdisplay as select codes.
(See CODES.)
(See RADAR.)
DEFENSE AREA– Any airspace of the contiguous
United States that is not an ADIZ in which the control
of aircraft is required for reasons of national security.
DEFENSE VISUAL FLIGHT RULES − Rules
applicable to flights within an ADIZ conducted under
the visual flight rules in 14 CFR Part 91.
(See AIR DEFENSE IDENTIFICATION ZONE.)
(Refer to 14 CFR Part 91.)
(Refer to 14 CFR Part 99.)
DELAY ASSIGNMENT (DAS) − Delays are distrib-
uted to aircraft based on the traffic managementprogram parameters. The delay assignment iscalculated in 15 −minute increments and appears as a
table in Traffic Flow Management System (TFMS).
DELAY INDEFINITE (REASON IF KNOWN)
EXPECT FUR THER CLEARANCE (TIME) − Used
by ATC to inform a pilot when an accurate estimateof the delay time and the reason for the delay cannotimmediately be determined; e.g., a disabled aircraft
Pilot/Controller Glossary 10/12/17
PCG D−2on the runway, terminal or center area saturation,
weather below landing minimums, etc.
(See EXPECT FURTHER CLEARANCE (TIME).)
DELAY TIME − The amount of time that the arrival
must lose to cross the meter fix at the assigned meter
fix time. This is the difference between ACLT andVTA.
DEPARTURE CENTER − The ARTCC having
jurisdiction for the airspace that generates a flight tothe impacted airport.
DEPARTURE CONTROL − A function of an
approach control facility providing air traffic control
service for departing IFR and, under certainconditions, VFR aircraft.
(See APPROACH CONTROL FACILITY.)
(Refer to AIM.)
DEPARTURE SEQUENCING PROGRAM − A
program designed to assist in achieving a specifiedinterval over a common point for departures.
DEPARTURE TIME − The time an aircraft becomes
airborne.
DESCEND VIA– An abbreviated A TC clearance that
requires compliance with a published procedure
lateral path and associated speed restrictions andprovides a pilot-discretion descent to comply withpublished altitude restrictions.
DESCENT SPEED ADJUSTMENTS − Speed decel-
eration calculations made to determine an accurateVTA. These calculations start at the transition pointand use arrival speed segments to the vertex.
DESIGNATED COMMON TRAFFIC ADVISORY
FREQUENCY (CTAF) AREA- In Alaska, inaddition to being designated for the purpose ofcarrying out airport advisory practices whileoperating to or from an airport without an operatingairport traffic control tower, a CTAF may also bedesignated for the purpose of carrying out advisorypractices for operations in and through areas with ahigh volume of VFR traffic.
DESIRED COURSE −
a.True− A predetermined desired course direction
to be followed (measured in degrees from true north).
b.Magnetic − A predetermined desired course
direction to be followed (measured in degrees fromlocal magnetic north).DESIRED TRACK − The planned or intended track
between two waypoints. It is measured in degreesfrom either magnetic or true north. The ins tantaneous
angle m ay change from point to point along the great
circle track between waypoints.
DETRESFA (DISTRESS PHASE) [ICAO] − The
code word used to designate an emergency phasewherein there is reasonable certainty that an aircraftand its occupants are threatened by grave andimminent danger or require immediate assistance.
DEVIA TIONS−
a.A departure from a current clearance, such as an
off course maneuver to avoid weather or turbulence.
b.Where specifically authorized in the CFRs and
requested by the pilot, ATC may permit pilots todeviate from certain regulations.
DH−
(See DECISION HEIGHT.)
DH [ICAO] −
(See ICAO Term DECISION ALTITUDE/
DECISION HEIGHT.)
DIGITAL-AUTOMATIC TERMINAL INFORMA-
TION SERVICE (D-ATIS) − The service provides
text messages to aircraft, airlines, and other usersoutside the standard reception range of conventionalATIS via landline and data link communications tothe cockpit. Also, the service provides a computer −
synthesized voice message that can be transmitted to
all aircraft within range of existing transmitters. TheTerminal Data Link System (TDLS) D-ATISapplication u ses weather inputs from local automated
weather sources or manually entered meteorologicaldata together with preprogrammed menus to providestandard information to users. Airports with D-ATIScapability are listed in the Chart Supplement U.S.
DIGITAL T ARGET− A computer −generated symbol
representing an aircraft’s position, based on a primary
return or radar beacon reply, shown on a digitaldisplay.
DIGITAL TERMINAL AUTOMATION SYSTEM
(DTAS)− A system where digital radar and beacon
data is presented on digital displays and theoperational program monitors the system perfor-mance on a real −time basis.
DIGITIZED TARGET − A computer −generated
indication shown on an analog radar display resulting
from a primary radar return or a radar beacon reply.
Pilot/Controller Glossary10/12/17
PCG D−3DIRECT− Straight line flight between two naviga-
tional aids, fixes, points, or any combination thereof.
When used by pilots in describing off-airway routes,points defining direct route segments becomecompulsory reporting points unless the aircraft isunder radar contact.
DIRECTLY BEHIND − An aircraft is considered to
be operating directly behind when it is following theactual flight path of the lead aircraft over the surfaceof the earth except when applying wake turbulenceseparation criteria.
DISCRETE BEACON CODE −
(See DISCRETE CODE.)
DISCRETE CODE − As used in the Air Traffic
Control Radar Beacon System (ATCRBS), any oneof the 4096 selectable Mode 3/A aircraft transpondercodes except those ending in zero zero; e.g., discretecodes: 0010, 1201, 2317, 7777; nondiscrete codes:0100, 1200, 7700. Nondiscrete codes are normallyreserved for radar facilities that are not equipped with
discrete decoding capability and for other purposessuch as emer gencies (7700), VFR aircraft (1200), etc.
(See RADAR.)
(Refer to AIM.)
DISCRETE FREQUENCY − A separate radio
frequency for use in direct pilot-controller commu-nications in air traffic control which reducesfrequency congestion by controlling the number ofaircraft operating on a particular frequency at onetime. Discrete frequencies are normally designatedfor each control sector in en route/terminal ATCfacilities. Discrete frequencies are listed in the Chart
Supplement U.S. and the DOD FLIP IFR En RouteSupplement.
(See CONTROL SECTOR.)
DISPLACED THRESHOLD − A threshold that is
located at a point on the runway other than thedesignated beginning of the runway.
(See THRESHOLD.)
(Refer to AIM.)
DISTANCE MEASURING EQUIPMENT (DME) −
Equipment (airborne and ground) used to measure, in
nautical miles, the slant range distance of an aircraftfrom the DME navigational aid.
(See TACAN.)
(See VORTAC.)DISTRESS − A condition of being threatened by
serious and/or imminent danger and of requiringimmediate assistance.
DIVE BRAKES −
(See SPEED BRAKES.)
DIVERSE VECTOR AREA − In a radar environ-
ment, that area in which a prescribed departure route
is not required as the only suitable route to avoidobstacles. The area in which random radar vectorsbelow the MV A/MIA, established in accordance with
the TERPS criteria for diverse departures, obstaclesand terrain avoidance, may be issued to departingaircraft.
DIVERSION (DVRSN) − Flights that are required to
land at other than their original destination forreasons beyond the control of the pilot/company, e.g.
periods of significant weather.
DME−
(See DISTANCE MEASURING EQUIPMENT.)
DME FIX − A geographical position determined by
reference to a navigational aid which providesdistance and azimuth information. It is defined by aspecific distance in nautical miles and a radial,azimuth, or course (i.e., localizer) in degreesmagnetic from that aid.
(See DISTANCE MEASURING EQUIPMENT.)
(See FIX.)
DME SEPARATION − Spacing of aircraft in terms of
distances (nautical miles) determined by reference to
distance measuring equipment (DME).
(See DISTANCE MEASURING EQUIPMENT.)
DOD FLIP − Department of Defense Flight Informa-
tion Publications used for flight planning, en route,and terminal operations. FLIP is produced by theNational Geospatial −Intelligence Agency (NGA) for
world-wide use. United States Government FlightInformation Publications (en route charts andinstrument approach procedure charts) are incorpo-rated in DOD FLIP for use in the National AirspaceSystem (NAS).
DOMESTIC AIRSPACE − Airspace which overlies
the continental land mass of the United States plusHawaii and U.S. possessions. Domestic airspaceextends to 12 miles offshore.
DOWNBURST − A strong downdraft which induces
an outburst of damaging winds on or near the ground.Damaging winds, either straight or curved, are highly
Pilot/Controller Glossary 10/12/17
PCG D−4divergent. The sizes of downbursts vary from 1/2
mile or less to more than 10 miles. An intensedownburst often causes widespread damage. Damag-
ing winds, lasting 5 to 30 minutes, could reach speedsas high as 120 knots.
DOWNWIND LEG −
(See TRAFFIC PATTERN.)
DP−
(See INSTRUMENT DEPARTURE PROCEDURE.)
DRAG CHUTE − A parachute device installed on
certain aircraft which is deployed on landing roll toassist in deceleration of the aircraft.
DROP ZONE− Any pre-determined area upon which
parachutists or objects land after making anintentional parachute jump or drop.
(Refer to 14 CFR §105.3, Definitions)
DSP−
(See DEPARTURE SEQUENCING PROGRAM.)
DT−
(See DELAY TIME.)
DTAS−
(See DIGITAL TERMINAL AUTOMATION
SYSTEM.)
DUE REGARD − A phase of flight wherein an
aircraft commander of a State-operated aircraftassumes responsibility to separate his/her aircraft
from all other aircraft.
(See also FAA Order JO 7110.65, Para 1 −2−1,
WORD MEANINGS.)
DUTY RUNWAY −
(See RUNWAY IN USE/ACTIVE RUNWAY/DUTY
RUNWAY.)
DV A−
(See DIVERSE VECTOR AREA.)
DVFR−
(See DEFENSE VISUAL FLIGHT RULES.)
DVFR FLIGHT PLAN − A flight plan filed for a VFR
aircraft which intends to operate in airspace withinwhich the ready identification, location, and controlof aircraft are required in the interest of nationalsecurity.
DVRSN−
(See DIVERSION.)
DYNAMIC − Continuous review, evaluation, and
change to meet demands.
DYNAMIC RESTRICTIONS − Those restrictions
imposed by t he local facility on an “as needed” basis
to manage unpredictable fluctuations in trafficdemands.
Pilot/Controller Glossary10/12/17
PCG E−1E
EAS−
(See EN ROUTE AUTOMATION SYSTEM.)
EDCT−
(See EXPECT DEPARTURE CLEARANCE
TIME.)
EDST−
(See EN ROUTE DECISION SUPPORT TOOL)
EFC−
(See EXPECT FURTHER CLEARANCE (TIME).)
ELT−
(See EMERGENCY LOCATOR TRANSMITTER.)
EMERGENCY − A distress or an urgency condition.
EMERGENCY LOCATOR TRANSMITTER − A
radio transmitter attached to the aircraft structurewhich operates from its own power source on121.5 MHz and 243.0 MHz. It aids in locatingdowned aircraft by radiating a downward sweepingaudio tone, 2-4 times per second. It is designed tofunction without human action after an accident.
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
E-MSAW −
(See EN ROUTE MINIMUM SAFE ALTITUDE
WARNING.)
ENHANCED FLIGHT VISION SYSTEM (EFVS) −
An EFVS is an installed aircraft system which uses
an electronic means to provide a display of theforward external scene topography (the natural or
man−made features of a place or region especially in
a way to show their relative positions and elevation)through the use of imaging sensors, including but not
limited to forward −looking infrared, millimeter wave
radiometry, millimeter wave radar, or low −light level
image intensification. An EFVS includes the display
element, sensors, computers and power supplies,
indications, and controls. An operator’s authoriza-
tion to conduct an EFVS operation may have
provisions which allow pilots to conduct IAPs when
the reported weather is below minimums prescribed
on the IAP to be flown.
EN ROUTE AIR TRAFFIC CONTROL SER-
VICES− Air traffic control service provided aircrafton IFR flight plans, generally by centers, when these
aircraft are operating between departure anddestination terminal areas. When equipment, capa-bilities, and controller workload permit, certainadvisory/assistance services may be provided to VFR
aircraft.
(See AIR ROUTE TRAFFIC CONTROL
CENTER.)
(Refer to AIM.)
EN ROUTE AUTOMATION SYSTEM (EAS) − The
complex integrated environment consisting ofsituation display systems, surveillance systems andflight data processing, remote devices, decisionsupport tools, and the related communicationsequipment that form the heart of the automated IFRair traf fic control system. It interfaces with automated
terminal systems and is used in the control of en routeIFR aircraft.
(Refer to AIM.)
EN ROUTE CHARTS −
(See AERONAUTICAL CHART.)
EN ROUTE DECISION SUPPORT TOOL − An
automated tool provided at each Radar Associateposition in selected En Route facilities. This toolutilizes flight and radar data to determine present and
future trajectories for all active and proposal aircraftand provides enhanced automated flight datamanagement.
EN ROUTE DESCENT − Descent from the en route
cruising altitude which takes place along the route of
flight.
EN ROUTE HIGH ALTITUDE CHARTS −
(See AERONAUTICAL CHART.)
EN ROUTE LOW ALTITUDE CHARTS −
(See AERONAUTICAL CHART.)
EN ROUTE MINIMUM SAFE ALTITUDE WARN-
ING− A function of the EAS that aids the controller
by providing an alert when a tracked aircraft is belowor predicted by the computer to go below apredetermined minimum IFR altitude (MIA).
EN ROUTE SPACING PROGRAM (ESP) − A
program designed to assist the exit sector inachieving the required in-trail spacing.
Pilot/Controller Glossary 10/12/17
PCG E−2EN ROUTE TRANSITION −
a.Conventional STARs/SIDs. The portion of a
SID/STAR that connects to one or more en routeairway/jet route.
b.RNA V STARs/SIDs. The portion of a STAR
preceding the common route or point, or for a SID the
portion following, that is coded for a specific en routefix, airway or jet route.
ESP−
(See EN ROUTE SPACING PROGRAM.)
EST−
(See ESTIMATED.)
ESTABLISHED − To be stable or fixed at an altitude
or on a course, route, route segment, heading,
instrument approach or departure procedure, etc.
ESTIMATED (EST) −When used in NOTAMs
“EST” is a contraction that is used by the issuingauthority only when the condition is expected toreturn to service prior to the expiration time. Using“EST” lets the user know that this NOTAM has thepossibility of returning to service earlier than the
expiration time. Any NOTAM which includes an
“EST” will be auto −expired at the designated
expiration time.
ESTIMATED ELAPSED TIME [ICAO] − The
estimated time required to proceed from onesignificant point to another.
(See ICAO Term TOTAL ESTIMATED ELAPSED
TIME.)
ESTIMATED OFF-BLOCK TIME [ICAO] − The
estimated time at which the aircraft will commencemovement associated with departure.
ESTIMATED POSITION ERROR (EPE) −
(See Required Navigation Performance)
ESTIMATED TIME OF ARRIV AL − The time the
flight is estimated to arrive at the gate (scheduledoperators) or the actual runway on times fornonscheduled operators.
ESTIMATED TIME EN ROUTE − The estimated
flying time from departure point to destination(lift-off to touchdown).
ETA−
(See ESTIMATED TIME OF ARRIVAL.)ETE−
(See ESTIMATED TIME EN ROUTE.)
EXECUTE MISSED APPROACH − Instructions
issued to a pilot making an instrument approachwhich means continue inbound to the missedapproach point and execute the missed approachprocedure as described on the Instrument ApproachProcedure Chart or as previously assigned by ATC.The pilot may climb immediately to the altitudespecified in the missed approach procedure uponmaking a missed approach. No turns should beinitiated prior to reaching the missed approach point.
When conducting an ASR or PAR approach, executethe assigned missed approach procedure immediately
upon recei ving instructions to “execute missed
approach.”
(Refer to AIM.)
EXPECT (AL TITUDE) AT (TIME) or (FIX) − Used
under certain conditions to provide a pilot with an
altitude to be used in the event of two-waycommunications failure. It also provides altitudeinformation to assist the pilot in planning.
(Refer to AIM.)
EXPECT DEPARTURE CLEARANCE TIME(EDCT)− The runway release time assigned to an
aircraft in a traffic management program and shownon the flight progress strip as an EDCT.
(See GROUND DELAY PROGRAM.)
EXPECT FURTHER CLEARANCE (TIME) − The
time a pilot can expect to receive clearance beyond a
clearance limit.
EXPECT FURTHER CLEARANCE VIA (AIR-
WAYS, ROUTES OR FIXES) − Used to inform a
pilot of the routing he/she can expect if any part of the
route beyond a short range clearance limit differsfrom that filed.
EXPEDITE − Used by ATC when prompt com-
pliance is required to avoid the development of animminent situation. Expedite climb/descent normal-ly indicates to a pilot that the approximate best rateof climb/descent should be used without requiring an
exceptional change in aircraft handling characteris-tics.
Pilot/Controller Glossary10/12/17
PCG F−1F
FAF−
(See FINAL APPROACH FIX.)
FAST FILE − An FSS system whereby a pilot files a
flight plan via telephone that is recorded and latertranscribed for transmission to the appropriate airtraffic facility. (Alaska only.)
FAWP− Final Approach Waypoint
FCLT−
(See FREEZE CALCULATED LANDING TIME.)
FEATHERED PROPELLER − A propeller whose
blades have been rotated so that the leading andtrailing edges are nearly parallel with the aircraftflight path to stop or minimize drag and enginerotation. Normally used to indicate shutdown of areciprocating or turboprop engine due to malfunc-tion.
FEDERAL AIRWAYS −
(See LOW ALTITUDE AIRWAY STRUCTURE.)
FEEDER FIX − The fix depicted on Instrument
Approach Procedure Charts which establishes thestarting point of the feeder route.
FEEDER ROUTE − A route depicted on instrument
approach procedure charts to designate routes foraircraft to proceed from the en route structure to theinitial approach fix (IAF).
(See INSTRUMENT APPROACH
PROCEDURE.)
FERRY FLIGHT − A flight for the purpose of:
a.Returning an aircraft to base.
b.Delivering an aircraft from one location to
another.
c.Moving an aircraft to and from a maintenance
base.− Ferry flights, under certain conditions, may be
conducted under terms of a special flight permit.
FIELD ELEV A TION−
(See AIRPORT ELEVATION.)
FILED− Normally used in conjunction with flight
plans, meaning a flight plan has been submitted toATC.
FILED EN ROUTE DELAY − Any of the following
preplanned delays at points/areas along the route offlight which require special flight plan filing and
handling techniques.
a.Terminal Area Delay. A delay within a terminal
area for touch-and-go, low approach, or otherterminal area activity.
b.Special Use Airspace Delay. A delay within a
Military Operations Area, Restricted Area, WarningArea, or ATC Assigned Airspace.
c.Aerial Refueling Delay. A delay within an
Aerial Refueling Track or Anchor.
FILED FLIGHT PLAN − The flight plan as filed with
an ATS unit by the pilot or his/her designatedrepresentative without any subsequent changes orclearances.
FINAL− Commonly used to mean that an aircraft is
on the final approach course or is aligned with alanding area.
(See FINAL APPROACH COURSE.)
(See FINAL APPROACH-IFR.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
FINAL APPROACH [ICAO] − That part of an
instrument approach procedure which commences at
the specified final approach fix or point, or wheresuch a fix or point is not specified.
a.At the end of the last procedure turn, base turn
or inbound turn of a racetrack procedure, if specified;
or
b.At the point of interception of the last track
specified in the approach procedure; and ends at apoint in the vicinity of an aerodrome from which:
1.A landing can be made; or
2.A missed approach procedure is initiated.
FINAL APPROACH COURSE − A bearing/radial/
track of an instrument approach leading to a runwayor an extended runway centerline all without regardto distance.
FINAL APPROACH FIX − The fix from which the
final approach (IFR) to an airport is executed andwhich identifies the beginning of the final approachsegment. It is designated on Government charts bythe Maltese Cross symbol for nonprecisionapproaches and the lightning bolt symbol,designating the PFAF, for precision approaches; or
Pilot/Controller Glossary 10/12/17
PCG F−2when ATC directs a lower-than-published
glideslope/path or vertical path intercept altitude, it is
the resultant actual point of the glideslope/path orvertical path intercept.
(See FINAL APPROACH POINT.)
(See GLIDESLOPE INTERCEPT ALTITUDE.)(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
FINAL APPROACH-IFR − The flight path of an
aircraft which is inbound to an airport on a finalinstrument approach course, beginning at the finalapproach fix or point and extending to the airport orthe point where a circle-to-land maneuver or a missedapproach is executed.
(See FINAL APPROACH COURSE.)
(See FINAL APPROACH FIX.)(See FINAL APPROACH POINT.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
(See ICAO term FINAL APPROACH.)
FINAL APPROACH POINT − The point, applicable
only to a nonprecision approach with no depictedFAF (such as an on airport VOR), where the aircraftis established inbound on the final approach coursefrom the procedure turn and where the final approach
descent may be commenced. The FAP serves as theFAF and identifies the beginning of the finalapproach segment.
(See FINAL APPROACH FIX.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
FINAL APPROACH SEGMENT −
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
FINAL APPROACH SEGMENT [ICAO] − That
segment of an instrument approach procedure inwhich alignment and descent for landing areaccomplished.
FINAL CONTROLLER − The controller providing
information and final approach guidance during PAR
and ASR approaches utilizing radar equipment.
(See RADAR APPROACH.)
FINAL GUARD SERVICE − A value added service
provided in conjunction with LAA/RAA only during
periods of significant and fast changing weatherconditions that may affect landing and takeoffoperations.FINAL MONITOR AID − A high resolution color
display that is equipped with the controller alertsystem hardware/software used to monitor the notransgression zone (NTZ) during simultaneousparallel approach operations. The display includesalert algorithms providing the target predictors, acolor change alert when a target penetrates or ispredicted to penetrate the no transgression zone(NTZ), synthesized voice alerts, and digital mapping.
(See RADAR APPROACH.)
FINAL MONITOR CONTROLLER − Air Traffic
Control Specialist assigned to radar monitor theflight path of aircraft during simultaneous parallel(approach courses spaced less than 9000 feet/9200feet above 5000 feet) and simultaneous close parallel
approach operations. Each runway is assigned a finalmonitor controller during simultaneous parallel andsimultaneous close parallel ILS approaches.
FIR−
(See FLIGHT INFORMATION REGION.)
FIRST TIER CENTER − The ARTCC immediately
adjacent to the impacted center.
FIS−B−
(See FLIGHT INFORMATION
SERVICE −BROADCAST.)
FIX− A geographical position determined by visual
reference to the surface, by reference to one or moreradio NA V AIDs, by celestial plotting, or by anothernavigational device.
FIX BALANCING − A process whereby aircraft are
evenly distributed over several available arrival fixes
reducing delays and controller workload.
FLAG− A warning device incorporated in certain
airborne navigation and flight instruments indicating
that:
a.Instruments are inoperative or otherwise not
operating satisfactorily, or
b.Signal s trength or quality of the received signal
falls below acceptable values.
FLAG ALARM −
(See FLAG.)
FLAMEOUT − An emergency condition caused by a
loss of engine power.
FLAMEOUT PATTERN − An approach normally
conducted by a single-engine military aircraftexperiencing loss or anticipating loss of engine
Pilot/Controller Glossary10/12/17
PCG F−3power or control. The standard overhead approach
starts at a relatively high altitude over a runway(“high key”) followed by a continuous 180 degreeturn to a high, wide position (“low key”) followed by
a continuous 180 degree turn final. The standardstraight-in pattern starts at a point that results in astraight-in approach with a high rate of descent to the
runway. Flameout approaches terminate in the typeapproach requested by the pilot (normally fullstop).
FLIGHT CHECK − A call-sign prefix used by FAA
aircraft engaged in flight inspection/certification ofnavigational aids and flight procedures. The word“recorded” may be added as a suffix; e.g., “FlightCheck 320 recorded” to indicate that an automatedflight inspection is in progress in terminal areas.
(See FLIGHT INSPECTION.)
(Refer to AIM.)
FLIGHT FOLLOWING −
(See TRAFFIC ADVISORIES.)
FLIGHT INFORMATION REGION− An airspace of
defined dimensions within which Flight InformationService and Alerting Service are provided.
a.Flight Information Service. A service provided
for the purpose of giving advice and informationuseful for the safe and efficient conduct of flights.
b.Alerting Service. A service provided to notify
appropriate organizations regarding aircraft in needof search and rescue aid and to assist suchorganizations as required.
FLIGHT INFORMATION SERVICE − A service
provided for the purpose of giving advice andinformation useful for the safe and efficient conductof flights.
FLIGHT INFORMATION SERVICE −
BROADCAST (FIS−B)− A ground broadcast service
provided through the ADS −B Broadcast Services
network over the UAT data link that operates on 978
MHz. The FIS −B system provides pilots and flight
crews of properly equipped aircraft with a cockpitdisplay of certain aviation weather and aeronauticalinformation.
FLIGHT INSPECTION − Inflight investigation and
evaluation of a navigational aid to determine whether
it meets established tolerances.
(See FLIGHT CHECK.)
(See NAVIGATIONAL AID.)FLIGHT LEVEL − A level of constant atmospheric
pressure related to a reference datum of 29.92 inches
of mercury. Each is stated in three digits that representhundreds of feet. For example, flight level (FL) 250represents a barometric altimeter indication of25,000 feet; FL 255, an indication of 25,500 feet.
(See ICAO term FLIGHT LEVEL.)
FLIGHT LEVEL [ICAO] − A surface of constant
atmospheric pressure which is related to a specificpressure datum, 1013.2 hPa (1013.2 mb), and isseparated from other such surfaces by specificpressure intervals.
Note 1: A pressure type altimeter calibrated in
accordance with the standard atmosphere:
a.When set to a QNH altimeter setting, will
indicate altitude;b.When set to a QFE altimeter setting, will
indicate height above the QFE reference datum;andc.When set to a pressure of 1013.2 hPa
(1013.2 mb), may be used to indicate flight levels.
Note 2: The terms ‘height’ and ‘altitude,’ used in
Note 1 above, indicate altimetric rather than
geometric heights and altitudes.
FLIGHT LINE − A term used to describe the precise
movement of a civil photogrammetric aircraft alonga predetermined course(s) at a predetermined altitudeduring the actual photographic run.
FLIGHT MANAGEMENT SYSTEMS − A comput-
er system that uses a large data base to allow routesto be preprogrammed and fed into the system bymeans of a data loader. The system is constantlyupdated with respect to position accuracy byreference to conventional navigation aids. Thesophisticated program and its associated data baseensures that the most appropriate aids are automati-cally selected during the information update cycle.
FLIGHT PATH − A line, course, or track along which
an aircraft is flying or intended to be flown.
(See COURSE.)
(See TRACK.)
FLIGHT PLAN − Specified information relating to
the intended flight of an aircraft that is filed orally orin writing with an FSS or an ATC facility.
(See FAST FILE.)
(See FILED.)(Refer to AIM.)
FLIGHT PLAN AREA (FPA) − The geographical
area assigned to a flight service station (FSS) for the
Pilot/Controller Glossary 10/12/17
PCG F−4purpose of establishing primary responsibility for
services that may include search and rescue for VFR
aircraft, issuance of NOTAMs, pilot briefings,inflight services, broadcast services, emergencyservices, flight data processing, international opera-tions, and aviation weather services. Largeconsolidated FSS facilities may combine FPAs intolarger areas of responsibility (AOR).
(See FLIGHT SERVICE STATION.)
(See TIE-IN FACILITY .)
FLIGHT RECORDER − A general term applied to
any instrument or device that records informationabout the performance of an aircraft in flight or about
conditions encountered in flight. Flight recordersmay make records of airspeed, outside airtemperature, vertical acceleration, engine RPM,manifold pressure, and other pertinent variables for a
given flight.
(See ICAO term FLIGHT RECORDER.)
FLIGHT RECORDER [ICAO] − Any type of
recorder installed in the aircraft for the purpose ofcomplementing accident/incident investigation.
Note: See Annex 6 Part I, for specifications relating
to flight recorders.
FLIGHT SERVICE STATION (FSS) − An air traffic
facility which provides pilot briefings, flight planprocessing, en route flight advisories, search andrescue services, and assistance to lost aircraft andaircraft in emergency situations. FSS also relay ATC
clearances, process Notices to Airmen, broadcastaviation weather and aeronautical information, andadvise Customs and Immigration of transborderflights. In Alaska, FSS provide Airport AdvisoryServices.
(See FLIGHT PLAN AREA.)
(See TIE-IN FACILITY.)
FLIGHT STANDARDS DISTRICT OFFICE − An
FAA field office serving an assigned geographicalarea and staffed with Flight Standards personnel who
serve the aviation industry and the general public onmatters relating to the certification and operation ofair carrier and general aviation aircraft. Activitiesinclude general surveillance of operational safety,certification of airmen and aircraft, accidentprevention, investigation, enforcement, etc.
FLIGHT TERMINATION − The intentional and
deliberate process of terminating the flight of a UA in
the event of an unrecoverable lost link, loss ofcontrol, or other failure that compromises the safety
of flight.
FLIGHT TEST − A flight for the purpose of:
a.Investigating the operation/flight characteris-
tics of an aircraft or aircraft component.
b.Evaluating an applicant for a pilot certificate or
rating.
FLIGHT VISIBILITY −
(See VISIBILITY.)
FLIP−
(See DOD FLIP.)
FLY HEADING (DEGREES) − Informs the pilot of
the heading he/she should fly . The pilot may have to
turn to, or continue on, a specific compass directionin order to comply with the instructions. The pilot isexpected to turn in the shorter direction to the heading
unless otherwise instructed by ATC.
FLY-BY WAYPOINT − A fly-by waypoint requires
the use of turn anticipation to avoid overshoot of thenext flight segment.
FLY-OVER WAYPOINT − A fly-over waypoint
precludes any turn until the waypoint is overflownand is followed by an intercept maneuver of the nextflight segment.
FLY VISUAL TO AIRPORT −
(See PUBLISHED INSTRUMENT APPROACH
PROCEDURE VISUAL SEGMENT.)
FMA−
(See FINAL MONITOR AID.)
FMS−
(See FLIGHT MANAGEMENT SYSTEM.)
FORMATION FLIGHT − More than one aircraft
which, by prior arrangement between the pilots,operate as a single aircraft with regard to navigationand position reporting. Separation between aircraftwithin the formation is the responsibility of the flight
leader and the pilots of the other aircraft in the flight.
This includes transition periods when aircraft withinthe formation are maneuvering to attain separationfrom each other to effect individual control andduring join-up and breakaway.
a.A standard formation is one in which a
proximity of no more than 1 mile laterally orlongitudinally and within 100 feet vertically from the
flight leader is maintained by each wingman.
b.Nonstandard formations are those operating
under any of the following conditions:
Pilot/Controller Glossary10/12/17
PCG F−51.When the flight leader has requested and ATC
has approved other than standard formationdimensions.
2.When operating within an authorized altitude
reservation (ALTRV) or under the provisions of aletter of agreement.
3.When the operations are conducted in
airspace specifically designed for a special activity.
(See ALTITUDE RESERVATION.)
(Refer to 14 CFR Part 91.)
FRC−
(See REQUEST FULL ROUTE CLEARANCE.)
FREEZE/FROZEN − Terms used in referring to
arrivals which have been assigned ACLTs and to thelists in which they are displayed.
FREEZE CALCULATED LANDING TIME − A
dynamic parameter number of minutes prior to themeter fix calculated time of arrival for each aircraftwhen the TCLT is frozen and becomes an ACLT (i.e.,
the VTA is updated and consequently the TCLT ismodified as appropriate until FCLT minutes prior tometer fix calculated time of arrival, at which timeupdating is suspended and an ACLT and a frozenmeter fix crossing time (MFT) is assigned).
FREEZE HORIZON − The time or point at which an
aircraft’s STA becomes fixed and no longer fluctuates
with each radar update. This setting ensures aconstant time for each aircraft, necessary for themetering controller to plan his/her delay technique.This setting can be either in distance from the meterfix or a prescribed flying time to the meter fix.
FREEZE SPEED PARAMETER − A speed adapted
for each aircraft to determine fast and slow aircraft.Fast aircraft freeze on parameter FCLT and slowaircraft freeze on parameter MLDI.
FRICTION MEASUREMENT − A measurement of
the friction characteristics of the runway pavementsurface using continuous self-watering frictionmeasurement equipment in accordance with thespecifications, procedures and schedules contained
in AC 150/5320 −12, Measurement, Construction,
and Maintenance of Skid Resistant Airport Pavement
Surfaces.
FSDO−
(See FLIGHT STANDARDS DISTRICT OFFICE.)
FSPD−
(See FREEZE SPEED PARAMETER.)
FSS−
(See FLIGHT SERVICE STATION.)
FUEL DUMPING − Airborne release of usable fuel.
This does not include the dropping of fuel tanks.
(See JETTISONING OF EXTERNAL STORES.)
FUEL REMAINING − A phrase used by either pilots
or controllers when relating to the fuel remaining onboard until actual fuel exhaustion. When transmitting
such information in response to either a controllerquestion or pilot initiated cautionary advisory to airtraffic control, pilots will state the APPROXIMATENUMBER OF MINUTES the flight can continuewith the fuel remaining. All reserve fuel SHOULDBE INCLUDED in the time stated, as should anallowance for established fuel gauge system error.
FUEL SIPHONING − Unintentional release of fuel
caused by overflow, puncture, loose cap, etc.
FUEL VENTING −
(See FUEL SIPHONING.)
FUSED TARGET-
(See DIGITAL TARGET)
FUSION [STARS/CARTS]- the combination of all
available surveillance sources (airport surveillanceradar [ASR], air route surveillance radar [ARSR],ADS-B, etc.) into the display of a single trackedtarget for air traffic control separation services.FUSION is the equivalent of the currentsingle-sensor radar display. FUSION performance is
characteristic of a single-sensor radar display system.Terminal areas use mono-pulse secondary surveil-lance radar (ASR 9, Mode S or ASR 11, MSSR).
Pilot/Controller Glossary10/12/17
PCG G−1G
GATE HOLD PROCEDURES − Procedures at
selected airports to hold aircraft at the gate or otherground location whenever departure delays exceed or
are anticipated to exceed 15 minutes. The sequencefor departure will be maintained in accordance withinitial call −up unless modified by flow control
restrictions. Pilots should monitor the groundcontrol/clearance delivery frequency for enginestart/taxi advisories or new proposed start/taxi timeif the delay changes.
GBT−
(See GROUND −BASED TRANSCEIVER.)
GCA−
(See GROUND CONTROLLED APPROACH.)
GDP−
(See GROUND DELAY PROGRAM.)
GENERAL A VIATION − That portion of civil
aviation that does not include scheduled orunscheduled air carriers or commercial spaceoperations.
(See ICAO term GENERAL AVIATION.)
GENERAL A VIATION [ICAO] − All civil aviation
operations other than sche duled air services and
nonscheduled air transport operations for remunera-tion or hire.
GEO MAP − The digitized map markings associated
with the ASR-9 Radar System.
GLIDEPATH −
(See GLIDESLOPE.)
GLIDEPATH [ICAO]− A descent profile determined
for vertical guidance during a final approach.
GLIDEPATH INTERCEPT AL TITUDE−
(See GLIDESLOPE INTERCEPT ALTITUDE.)
GLIDESLOPE − Provides vertical guidance for
aircraft during approach and landing. The glideslope/
glidepath is based on the following:
a.Electronic components emitting signals which
provide vertical guidance by reference to airborneinstruments during instrument approaches such asILS orb.Visual ground aids, such as V ASI, which
provide vertical guidance for a VFR approach or forthe visual portion of an instrument approach andlanding.
c.PAR. Used by A TC to inform an aircraft making
a PAR approach of its vertical position (elevation)relative to the descent profile.
(See ICAO term GLIDEPATH.)
GLIDESLOPE INTERCEPT ALTITUDE − The
published minimum altitude to intercept theglideslope in the intermediate segment of aninstrument approach. Government charts use thelightning bolt symbol to identify this intercept point.
This intersection is called the Precise Final Approach
fix (PFAF). ATC directs a higher altitude, theresultant intercept becomes the PFAF.
(See FINAL APPROACH FIX.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
GLOBAL NA VIGATION SATELLITE SYSTEM
(GNSS) [ICAO] − GNSS refers collectively to the
worldwide positioning, navigation, and timingdetermination capability available from one or moresatellite constellation in conjunction with a networkof ground stations.
GLOBAL NA VIGATION SATELLITE SYSTEM
MINIMUM EN ROUTE IFR ALTITUDE (GNSSMEA)− The minimum en route IFR altitude on a
published ATS route or route segment which assures
acceptable Global Navigation Sate llite System
reception and meets obstacle clearance requirements.
(Refer to 14 CFR Part 91.)(Refer to 14 CFR Part 95.)
GLOBAL POSITIONING SYSTEM (GPS) −
GPS
refers to the worldwide positioning, navigationand timing determination capability available
from the U.S. satellite constellation. The service
provided by GPS for civil use is defined in theGPS Standard Positioning System PerformanceStandard. GPS is composed of space, control,and user elements.
GNSS [ICAO] −
(See GLOBAL NAVIGATION SATELLITE
SYSTEM .)
Pilot/Controller Glossary 10/12/17
PCG G−2GNSS MEA −
(See GLOBAL NAVIGATION SATELLITE
SYSTEM MINIMUM EN ROUTE IFRALTITUDE.)
GO AHEAD − Proceed with your message. Not to be
used for any other purpose.
GO AROUND − Instructions for a pilot to abandon
his/her approach to landing. Additional instructionsmay follow. Unless otherwise advised by ATC, aVFR aircraft or an aircraft conducting visualapproach should overfly the runway while climbingto traffic pattern altitude and enter the traffic patternvia the crosswind leg. A pilot on an IFR flight planmaking an instrument approach should execute thepublished missed approach procedure or proceed asinstructed by ATC; e.g., “Go around” (additionalinstructions if required).
(See LOW APPROACH.)
(See MISSED APPROACH.)
GPD−
(See GRAPHIC PLAN DISPLAY.)
GPS−
(See GLOBAL POSITIONING SYSTEM.)
GRAPHIC PLAN DISPLAY (GPD) − A view
available with EDST that provides a graphic displayof aircraft, traffic, and notification of predictedconflicts. Graphic routes for Current Plans and TrialPlans are displayed upon controller request.
(See EN ROUTE DECISION SUPPORT TOOL. )
GROSS NA VIGATION ERROR (GNE) − A lateral
deviation from a cleared track, normally in excess of
25 Nautical Miles (NM). More stringent standards(for example, 10NM in some parts of the NorthAtlantic region) may be used in certain regions tosupport reductions in lateral separation.
GROUND BASED AUGMENTATION SYSTEM
(GBAS)– A ground based GNSS station whichprovides local differential corrections, integrityparameters and approach data via VHF data broadcast
to GNSS users to meet real-time performancerequirements for CAT I precision approaches. Theaircraft applies the broadcast data to improve theaccuracy and integrity of its GNSS signals andcomputes the deviations to the selected approach. A
single ground station can serve multiple runway ends
up to an approximate radius of 23 NM. GROUND BASED AUGMENTATION SYSTEM
(GBAS) LANDING SYSTEM (GLS)- A type ofprecision IAP based on local augmentation of GNSS
data using a single GBAS station to transmit locallycorrected GNSS data, integrity parameters andapproach information. This improves the accuracy of
aircraft GNSS receivers’ signal in space, enabling the
pilot to fly a precision approach with much greaterflexibility, reliability and complexity. The GLSprocedure is published on standard IAP charts,features the title GLS with the designated runway and
minima as low as 200 feet DA. Future plans areexpected to support Cat II and CAT III operations.
GROUND −BASED TRANSCEIVER (GBT) − The
ground−based transmitter/receiver (transceiver) re-
ceives automatic dependent surveillance −broadcast
messages, which are forwarded to an air trafficcontrol facility for processing and display with other
radar targets on the plan position indicator (radardisplay).
(See AUTOMATIC DEPENDENT
SURVEILLANCE-BROADCAST.)
GROUND CLUTTER − A pattern produced on the
radar scope by ground returns which may degradeother radar returns in the affected area. The effect ofground clutter is minimized by the use of movingtarget indicator (MTI) circuits in the radar equipmentresulting in a radar presentation which displays onlytargets which are in motion.
(See CLUTTER.)
GROUND COMMUNICATION OUTLET (GCO) −
An unstaffed, remotely controlled, ground/groundcommunications facility. Pilots at uncontrolledairports may contact ATC and FSS via VHF to atelephone connection to obtain an instrumentclearance or close a VFR or IFR flight plan. They may
also get an updated weather briefing prior to takeoff.Pilots will use four “key clicks” on the VHF radio tocontact the appropriate ATC facility or six “keyclicks” to contact the FSS. The GCO system isintended to be used only on the ground.
GROUND CONTROLLED APPROACH − A radar
approach system operated from the ground by airtraffic control personnel transmitting instructions tothe pilot by radio. The approach may be conductedwith surveillance radar (ASR) only or with bothsurveillance and precision approach radar (PAR).Usage of the term “GCA” by pilots is discouragedexcept when referring to a GCA facility. Pilots should
specifically request a “PAR” approach when a
Pilot/Controller Glossary10/12/17
PCG G−3precision radar approach is desired or request an
“ASR” or “surveillance” approach when a nonpreci-sion radar approach is desired.
(See RADAR APPROACH.)
GROUND DELAY PROGRAM (GDP) − A traffic
management process administered by the ATCSCC;when aircraft are held on the ground. The purpose of
the program is to support the TM mission and limitairborne holding. It is a flexible program and may be
implemented in various forms depending upon theneeds of the AT system. Ground delay programsprovide for equitable assignment of delays to allsystem users.
GROUND SPEED− The speed of an aircraft relativeto the surface of the earth.
GROUND STOP (GS) − The GS is a process that
requires aircraft that meet a specific criteria to remain
on the ground. The criteria may be airport specific,airspace specific, or equipment specific; for example,
all departures to San Francisco, or all departuresentering Yorktown sector, or all Category I and IIaircraft going to Charlotte. GSs normally occur with
little or no warning.
GROUND VISIBILITY −
(See VISIBILITY.)
GS−
(See GROUND STOP.)
Pilot/Controller Glossary10/12/17
PCG H−1H
HAA−
(See HEIGHT ABOVE AIRPORT.)
HAL−
(See HEIGHT ABOVE LANDING.)
HANDOFF − An action taken to transfer the radar
identification of an aircraft from one controller toanother if the aircraft will enter the receivingcontroller’s airspace and radio communications with
the aircraft will be transferred.
HAR−
(See HIGH ALTITUDE REDESIGN .)
HAT−
(See HEIGHT ABOVE TOUCHDOWN.)
HAVE NUMBERS − Used by pilots to inform ATC
that they have received runway, wind, and altimeterinformation only.
HAZARDOUS INFLIGHT WEATHER ADVISO-
RY SERVICE − Continuous r ecorded hazar dous
inflight weather forecasts broadcasted to airbornepilots over selected VOR outlets defined as anHIWAS BROADCAST AREA.
HAZARDOUS WEATHER INFORMATION −
Summary of significant meteorological information(SIGMET/WS), convective significant meteorologi-cal information (convective SIGMET/WST), urgentpilot weather reports (urgent PIREP/UUA), centerweather advisories (CWA), airmen’s meteorologicalinformation (AIRMET/WA) and any other weathersuch as isolated thunderstorms that are rapidlydeveloping and increasing in intensity, or lowceilings and visibilities that are becoming wide-spread which is considered significant and are notincluded in a current hazardous weather advisory.
HEAVY (AIRCRAFT) −
(See AIRCRAFT CLASSES.)
HEIGHT ABOVE AIRPORT − The height of the
Minimum Descent Altitude above the publishedairport elevation. This is published in conjunctionwith circling minimums.
(See MINIMUM DESCENT ALTITUDE.)HEIGHT ABOVE LANDING − The height above a
designated helicopter landing area used for helicopter
instrument approach procedures.
(Refer to 14 CFR Part 97.)
HEIGHT ABOVE TOUCHDOWN − The height of
the Decision Height or Minimum Descent Altitudeabove the highest runway elevation in the touchdown
zone (first 3,000 feet of the runway). HAT ispublished on instrument approach charts in conjunc-
tion with all straight-in minimums.
(See DECISION HEIGHT.)
(See MINIMUM DESCENT ALTITUDE.)
HELICOPTER − A heavier-than-air aircraft sup-
ported in flight chiefly by the reactions of the air onone or more power-driven rotors on substantiallyvertical axes.
HELIPAD − A small, designated area, usually with a
prepared surface, on a heliport, airport, landing/take-
off area, apron/ramp, or movement area used fortakeoff, landing, or parking of helicopters.
HELIPORT − An area of land, water, or structure used
or intended to be used for the landing and takeoff ofhelicopters and includes its buildings and facilities if
any.
HELIPORT REFERENCE POINT (HRP) − The
geographic center of a heliport.
HERTZ− The standard radio equivalent of frequency
in cycles per second of an electromagnetic wave.Kilohertz (kHz) is a frequency of one thousand cycles
per second. Megahertz (MHz) is a frequency of onemillion cycles per second.
HF−
(See HIGH FREQUENCY.)
HF COMMUNICA TIONS−
(See HIGH FREQUENCY COMMUNICATIONS.)
HIGH ALTITUDE REDESIGN (HAR) − A level of
non−restrictive routing (NRR) service for aircraft
that have all waypoints associated with the HARprogram in their flight management systems orRNA V equipage.
HIGH FREQUENCY − The frequency band between
3 and 30 MHz.
(See HIGH FREQUENCY COMMUNICATIONS.)
Pilot/Controller Glossary 10/12/17
PCG H−2HIGH FREQUENCY COMMUNICA TIONS− High
radio frequencies (HF) between 3 and 30 MHz usedfor air-to-ground voice communication in overseasoperations.
HIGH SPEED EXIT −
(See HIGH SPEED TAXIWAY.)
HIGH SPEED TAXIWAY − A long radius taxiway
designed and provided with lighting or marking todefine the path of aircraft, traveling at high speed (up
to 60 knots), from the runway center to a point on thecenter of a taxiway. Also referred to as long radiusexit or turn-off taxiway. The high speed taxiway isdesigned to expedite aircraft turning off the runwayafter landing, thus reducing runway occupancy time.
HIGH SPEED TURNOFF −
(See HIGH SPEED TAXIWAY.)
HIWAS−
(See HAZARDOUS INFLIGHT WEATHER
ADVISORY SERVICE.)
HIWAS AREA −
(See HAZARDOUS INFLIGHT WEATHER
ADVISORY SERVICE.)
HIWAS BROADCAST AREA − A geographical area
of responsibility including one or more HIWASoutlet areas assigned to a FSS for hazardous weather
advisory broadcasting.
HIWAS OUTLET AREA − An area defined as a 150
NM radius of a HIWAS outlet, expanded as necessary
to provide coverage.
HOLD FOR RELEASE − Used by ATC to delay an
aircraft for traf fic management reasons; i.e., weather,
traffic volume, etc. Hold for release instructions(including departure delay information) are used toinform a pilot or a controller (either directly or
through an authorized relay) that an IFR departure
clearance is not valid until a release time or additional
instructions have been received.
(See ICAO term HOLDING POINT.)
HOLD IN LIEU OF PROCEDURE TURN − A hold
in lieu of procedure turn shall be established over afinal or intermediate fix when an approach can bemade from a properly aligned holding pattern. Thehold in lieu of procedure turn permits the pilot toalign with the final or intermediate segment of theapproach and/or descend in the holding pattern to analtitude that will permit a normal descent to the final
approach fix altitude. The hold in lieu of procedureturn is a required maneuver (the same as a procedure
turn) unless the aircraft is being radar vectored to thefinal approach course, when “NoPT” is shown on theapproach chart, or when the pilot requests or thecontroller advises the pilot to make a “straight −in”
approach.
HOLD PROCEDURE − A predetermined maneuver
which keeps aircraft within a specified airspace while
awaiting further clearance from air traffic control.Also used during ground operations to keep aircraftwithin a specified area or at a specified point whileawaiting further clearance from air traffic control.
(See HOLDING FIX.)
(Refer to AIM.)
HOLDING FIX − A specified fix identifiable to a
pilot by NA V AIDs or visual reference to the groundused as a reference point in establishing andmaintaining the position of an aircraft while holding.
(See FIX.)
(See VISUAL HOLDING.)(Refer to AIM.)
HOLDING POINT [ICAO] − A specified location,
identified by visual or other means, in the vicinity of
which the position of an aircraft in flight ismaintained in accordance with air traffic controlclearances.
HOLDING PROCEDURE −
(See HOLD PROCEDURE.)
HOLD-SHORT POINT − A point on the runway
beyond which a landing aircraft with a LAHSOclearance is not authorized to proceed. This pointmay be located prior to an intersecting runway,taxiway, predetermined point, or approach/departure
flight path.
HOLD-SHORT POSITION LIGHTS − Flashing
in-pavement white lights located at specifiedhold-short points.
HOLD-SHORT POSITION MARKING − The
painted runway marking located at the hold-shortpoint on all LAHSO runways.
HOLD-SHORT POSITION SIGNS − Red and white
holding position signs located alongside thehold-short point.
Pilot/Controller Glossary10/12/17
PCG H−3HOMING − Flight toward a NA V AID, without
correcting for wind, by adjusting the aircraft heading
to maintain a relative bearing of zero degrees.
(See BEARING.)
(See ICAO term HOMING.)
HOMING [ICAO] − The procedure of using the
direction-finding equipment of one radio station with
the emission of another radio station, where at leastone of the stations is mobile, and whereby the mobilestation proceeds continuously towards the other
station.
HOVER CHECK − Used to describe when a
helicopter/VTOL aircraft requires a stabilized hoverto conduct a performance/power check prior to hover
taxi, air taxi, or takeoff. Altitude of the hover willvary based on the purpose of the check.HOVER T AXI − Used to describe a helicopter/VTOL
aircraft movement conducted above the surface andin ground effect at airspeeds less than approximately20 knots. The actual height may vary, and somehelicopters may require hover taxi above 25 feet AGL
to reduce ground effect turbulence or provideclearance for cargo slingloads.
(See AIR TAXI.)
(See HOVER CHECK.)(Refer to AIM.)
HOW DO YOU HEAR ME? − A question relating to
the quality of the transmission or to determine howwell the transmission is being received.
HZ−
(See HERTZ.)
Pilot/Controller Glossary10/12/17
PCG I−1I
I SAY AGAIN − The message will be repeated.
IAF−
(See INITIAL APPROACH FIX.)
IAP−
(See INSTRUMENT APPROACH
PROCEDURE.)
IAWP− Initial Approach Waypoint
ICAO−
(See ICAO Term INTERNATIONAL CIVIL
AVIATION ORGANIZATION.)
ICING− The accumulation of airframe ice.
Types of icing are:
a.Rime Ice− Rough, milky, opaque ice formed by
the instantaneous freezing of small supercooledwater droplets.
b.Clear Ice − A glossy, clear, or translucent ice
formed by the relatively slow freezing or largesupercooled water droplets.
c.Mixed− A mixture of clear ice and rime ice.
Intensity of icing:
a.Trace− Ice becomes perceptible. Rate of
accumulation is slightly greater than the rate ofsublimation. Deicing/anti-icing equipment is notutilized unless encountered for an extended period of
time (over 1 hour).
b.Light− The rate of accumulation may create a
problem if flight is prolonged in this environment(over 1 hour). Occasional use of deicing/anti-icingequipment removes/prevents accumulation. It doesnot present a problem if the deicing/anti-icingequipment is used.
c.Moderate − The rate of accumulation is such that
even short encounters become potentially hazardousand use of deicing/anti-icing equipment or flightdiversion is necessary.
d.Severe− The rate of ice accumulation is such
that ice protection systems fail to remove theaccumulation of ice, or ice accumulates in locationsnot normally prone to icing, such as areas aft ofprotected surfaces and any other areas identified bythe manufacturer. Immediate exit from the condition
is necessary.
Note:
Severe icing is aircraft dependent, as are the other
categories of icing intensity. Severe icing may
occur at any ice accumulation rate.
IDENT− A request for a pilot to activate the aircraft
transponder identification feature. This will help thecontroller to confirm an aircraft identity or to identify
an aircraft.
(Refer to AIM.)
IDENT FEATURE − The special feature in the Air
Traffic Control Radar Beacon System (ATCRBS)equipment. It is used to immediately distinguish one
displayed beacon target from other beacon targets.
(See IDENT.)
IDENTIFICATION [ICAO] − The situation which
exists when the position indication of a particularaircraft is seen on a situation display and positivelyidentified.
IF−
(See INTERMEDIATE FIX.)
IFIM−
(See INTERNATIONAL FLIGHT INFORMATION
MANUAL.)
IF NO TRANSMISSION RECEIVED FOR
(TIME)− Used by ATC in radar approaches to prefix
procedures which should be followed by the pilot inevent of lost communications.
(See LOST COMMUNICATIONS.)
IFR−
(See INSTRUMENT FLIGHT RULES.)
IFR AIRCRAFT − An aircraft conducting flight in
accordance with instrument flight rules.
IFR CONDITIONS − Weather conditions below the
minimum for flight under visual flight rules.
(See INSTRUMENT METEOROLOGICAL
CONDITIONS.)
IFR DEPARTURE PROCEDURE −
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(Refer to AIM.)
IFR FLIGHT −
(See IFR AIRCRAFT.)
Pilot/Controller Glossary 10/12/17
PCG I−2IFR LANDING MINIMUMS −
(See LANDING MINIMUMS.)
IFR MILITARY TRAINING ROUTES (IR) − Routes
used by the Department of Defense and associatedReserve and Air Guard units for the purpose ofconducting low-altitude navigation and tacticaltraining in both IFR and VFR weather conditionsbelow 10,000 feet MSL at airspeeds in excess of 250
knots IAS.
IFR TAKEOFF MINIMUMS AND DEPARTURE
PROCEDURES − Title 14 Code of Federal
Regulations Part 91, prescribes standard takeoff rules
for certain civil users. At some airports, obstructionsor other factors require the establishment ofnonstandard takeoff minimums, departure proce-dures, or both to assist pilots in avoiding obstaclesduring climb to the minimum en route altitude. Those
airports are listed in FAA/DOD Instrument Approach
Procedures (IAPs) Charts under a section entitled“IFR Takeoff Minimums and Departure Procedures.”
The FAA/DOD IAP chart legend illustrates thesymbol used to alert the pilot to nonstandard takeoffminimums and departure procedures. When depart-ing IFR from such airports or from any airports wherethere are no departure procedures, DPs, or ATCfacilities available, pilots should advise ATC of anydeparture limitations. Controllers may query a pilotto determine acceptable departure directions, turns,or headings after takeoff. Pilots should be familiarwith the departure procedures and must assure thattheir aircraft can meet or exceed any specified climbgradients.
IF/IAWP− Intermediate Fix/Initial Approach Way-
point. The waypoint where the final approach course
of a T approach meets the crossbar of the T. Whendesignated (in conjunction with a TAA) thiswaypoint will be used as an IAWP when approaching
the airport from certain directions, and as an IFWPwhen beginning the approach from another IAWP.
IFWP− Intermediate Fix Waypoint
ILS−
(See INSTRUMENT LANDING SYSTEM.)
ILS CATEGORIES − 1. Category I. An ILS approach
procedure which provides for approach to a heightabove touchdown of not less than 200 feet and withrunway visual range of not less than 1,800 feet. −
2. Special Authorization Category I. An ILSapproach procedure which provides for approach toa height above touchdown of not less than 150 feet
and with runway visual range of not less than 1,400feet, HUD to DH. 3. Category II. An ILS approachprocedure which provides for approach to a heightabove touchdown of not less than 100 feet and withrunway visual range of not less than 1,200 feet (with
autoland or HUD to touchdown and noted onauthorization, RVR 1,000 feet). − 4. Special
Authorization Category II with Reduced Lighting.An ILS approach procedure which provides forapproach to a height above touchdown of not lessthan 100 feet and with runway visual range of not less
than 1,200 feet with autoland or HUD to touchdownand noted on authorization (no touchdown zone andcenterline lighting are required). − 5. Category III:
a.IIIA.−An ILS approach procedure which
provides for approach without a decision heightminimum and with runway visual range of not lessthan 700 feet.
b.IIIB.−An ILS approach procedure which
provides for approach without a decision heightminimum and with runway visual range of not lessthan 150 feet.
c.IIIC.−An ILS approach procedure which
provides for approach without a decision heightminimum and without runway visual rangeminimum.
ILS PRM APPROACH − An instrument landing
system (ILS) approach conducted to parallel runways
whose extended centerlines are separated by less than4,300 feet and at least 3,000 feet where independentclosely spaced approaches are permitted. Also usedin conjunction with an LDA PRM, RNA V PRM orGLS PRM approach to conduct Simultaneous OffsetInstrument Approach (SOIA) operations. NoTransgression Zone (NTZ) monitoring is required to
conduct these approaches. ATC utilizes an enhanceddisplay with alerting and, with certain runwayspacing, a high update rate PRM surveillance sensor.
Use of a secondary monitor frequency, pilot PRMtraining, and publication of an Attention All UsersPage are also required for all PRM approaches.
(Refer to AIM)
IM−
(See INNER MARKER. )
IMC−
(See INSTRUMENT METEOROLOGICAL
CONDITIONS.)
Pilot/Controller Glossary10/12/17
PCG I−3IMMEDIATELY − Used by ATC or pilots when such
action compliance is required to avoid an imminentsituation.
INCERFA (Uncertainty Phase) [ICAO] − A situation
wherein uncertainty exists as to the safety of anaircraft and its occupants.
INCREASE SPEED TO (SPEED) −
(See SPEED ADJUSTMENT.)
INERTIAL NA VIGATION SYSTEM − An RNA V
system which is a form of self-contained navigation.
(See Area Navigation/RNAV.)
INFLIGHT REFUELING −
(See AERIAL REFUELING.)
INFLIGHT WEATHER ADVISORY −
(See WEATHER ADVISORY.)
INFORMATION REQUEST − A request originated
by an FSS for information concerning an overdueVFR aircraft.
INITIAL APPROACH FIX − The fixes depicted on
instrument approach procedure charts that identifythe beginning of the initial approach segment(s).
(See FIX.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
INITIAL APPROACH SEGMENT −
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
INITIAL APPROACH SEGMENT [ICAO] − That
segment of an instrument approach procedurebetween the initial approach fix and the intermediate
approach fix or, where applicable, the final approachfix or point.
INLAND NA VIGATION FACILITY − A navigation
aid on a North American Route at which the commonroute and/or the noncommon route begins or ends.
INNER MARKER − A marker beacon used with an
ILS (CAT II) precision approach located between themiddle marker and the end of the ILS runway,transmitting a radiation pattern keyed at six dots persecond and indicating to the pilot, both aurally andvisually, that he/she is at the designated decisionheight (DH), normally 100 feet above the touchdown
zone elevation, on the ILS CAT II approach. It alsomarks progress during a CAT III approach.
(See INSTRUMENT LANDING SYSTEM.)
(Refer to AIM.)INNER MARKER BEACON −
(See INNER MARKER.)
INREQ−
(See INFORMATION REQUEST.)
INS−
(See INERTIAL NAVIGATION SYSTEM.)
INSTRUMENT APPROACH −
(See INSTRUMENT APPROACH
PROCEDURE.)
INSTRUMENT APPROACH PROCEDURE − A
series of predetermined maneuvers for the orderlytransfer of an aircraft under instrument flightconditions from the beginning of the initial approach
to a landing or to a point from which a landing maybe made visually. It is prescribed and approved for aspecific airport by competent authority.
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
a.U.S. civil standard instrument approach
procedures are approved by the FAA as prescribedunder 14 CFR Part 97 and are available for publicuse.
b.U.S. military standard instrument approach
procedures are approved and published by theDepartment of Defense.
c.Special instrument approach procedures are
approved by the FAA for individual operators but are
not published in 14 CFR Part 97 for public use.
(See ICAO term INSTRUMENT APPROACH
PROCEDURE.)
INSTRUMENT APPROACH OPERATIONS
[ICAO]* An approach and landing using instruments
for navigation guidance based on an instrumentapproach procedure. There are two methods forexecuting instrument approach operations:
a.A two−dimensional (2D) instrument approach
operation, using lateral navigation guidance only;and
b.A three−dimensional (3D) instrument approach
operation, using both lateral and vertical navigationguidance.
Note: Lateral and vertical navigation guidance
refers to the guidance provided either by:a) a ground −based radio navigation aid; or
b) computer −generated navigation data from
Pilot/Controller Glossary 10/12/17
PCG I−4ground−based, space −based, self −contained
navigation aids or a combination of these.
(See ICAO term INSTRUMENT APPROACH
PROCEDURE.)
INSTRUMENT APPROACH PROCEDURE
[ICAO]− A series of predetermined maneuvers by
reference to flight instruments with specifiedprotection from obstacles from the initial approachfix, or where applicable, from the beginning of adefined arrival route to a point from which a landing
can be completed and thereafter, if a landing is notcompleted, to a position at which holding or en route
obstacle clearance criteria apply.
(See ICAO term INSTRUMENT APPROACH
OPERATIONS)
INSTRUMENT APPROACH PROCEDURES
CHARTS −
(See AERONAUTICAL CHART.)
INSTRUMENT DEPARTURE PROCEDURE
(DP)− A preplanned instrument flight rule (IFR)
departure procedure published for pilot use, ingraphic or textual format, that provides obstructionclearance from the terminal area to the appropriate en
route structure. There are two types of DP, ObstacleDeparture Procedure (ODP), printed either textuallyor graphically, and, Standard Instrument Departure(SID), which is always printed graphically.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(See OBSTACLE DEPARTURE PROCEDURES.)
(See STANDARD INSTRUMENT DEPARTURES.)(Refer to AIM.)
INSTRUMENT DEPAR TURE PROCEDURE (DP)
CHARTS −
(See AERONAUTICAL CHART.)
INSTRUMENT FLIGHT RULES − Rules governing
the procedures for conducting instrument flight. Alsoa term used by pilots and controllers to indicate typeof flight plan.
(See INSTRUMENT METEOROLOGICAL
CONDITIONS.)
(See VISUAL FLIGHT RULES.)
(See VISUAL METEOROLOGICAL
CONDITIONS.)
(See ICAO term INSTRUMENT FLIGHT
RULES.)
(Refer to AIM.)INSTRUMENT FLIGHT RULES [ICAO] − A set of
rules governing the conduct of flight underinstrument meteorological conditions.
INSTRUMENT LANDING SYSTEM − A precision
instrument approach system which normally consists
of the following electronic components and visualaids:
a.Localizer.
(See LOCALIZER.)
b.Glideslope.
(See GLIDESLOPE.)
c.Outer Marker.
(See OUTER MARKER.)
d.Middle Marker.
(See MIDDLE MARKER.)
e.Approach Lights.
(See AIRPORT LIGHTING.)
(Refer to 14 CFR Part 91.)(Refer to AIM.)
INSTRUMENT METEOROLOGICAL CONDI-
TIONS− Meteorological conditions expressed in
terms of visibility, distance from cloud, and ceilingless than the minima specified for visual meteorolog-
ical conditions.
(See INSTRUMENT FLIGHT RULES.)
(See VISUAL FLIGHT RULES.)(See VISUAL METEOROLOGICAL
CONDITIONS.)
INSTRUMENT RUNWAY − A runway equipped
with electronic and visual navigation aids for whicha precision or nonprecision approach procedurehaving straight-in landi ng minimums has been
approved.
(See ICAO term INSTRUMENT RUNWAY.)
INSTRUMENT RUNWAY [ICAO] − One of the
following types of runways intended for theoperation of aircraft using instrument approachprocedures:
a.Nonprecision Approach Runway −An instru-
ment runway served by visual aids and a nonvisualaid providing at least directional guidance adequatefor a straight-in approach.
b.Precision Approach Runway, Category I −An
instrument runway served by ILS and visual aidsintended for operations down to 60 m (200 feet)decision height and down to an RVR of the order of800 m.
Pilot/Controller Glossary10/12/17
PCG I−5c.Precision Approach Runway, Category II −An
instrument runway served by ILS and visual aidsintended for operations down to 30 m (100 feet)decision height and down to an RVR of the order of400 m.
d.Precision Approach Runway , Category III −An
instrument runway served by ILS to and along thesurface of the runway and:
1.Intended for operations down to an RVR of
the order of 200 m (no decision height beingapplicable) using visual aids during the final phase of
landing;
2.Intended for operations down to an RVR of
the order of 50 m (no decision height beingapplicable) using visual aids for taxiing;
3.Intended for operations without reliance on
visual reference for landing or taxiing.
Note 1: See Annex 10 Volume I, Part I, Chapter 3,
for related ILS specifications.
Note 2: Visual aids need not necessarily be
matched to the scale of nonvisual aids provided.The criterion for the selection of visual aids is theconditions in which operations are intended to be
conducted.
INTEGRITY − The ability of a system to provide
timely warnings to users when the system should not
be used for navigation.
INTERMEDIATE APPROACH SEGMENT −
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
INTERMEDIATE APPROACH SEGMENT
[ICAO]− That segment of an instrument approach
procedure between either the intermediate approachfix and the final approach fix or point, or between theend of a reversal, race track or dead reckoning trackprocedure and the final approach fix or point, asappropriate.
INTERMEDIATE FIX − The fix that identifies the
beginning of the intermediate approach segment of an
instrument approach procedure. The fix is notnormally identified on the instrument approach chart
as an intermediate fix (IF).
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
INTERMEDIATE LANDING − On the rare occasion
that this option is requested, it should be approved.The departure center, however, must advise theATCSCC so that the appropriate delay is carried overand assigned at the intermediate airport. An
intermediate landing airport within the arrival center
will not be accepted without coordination with andthe approval of the ATCSCC.
INTERNATIONAL AIRPORT − Relating to interna-
tional flight, it means:
a.An airport of entry which has been designated
by the Secretary of Treasury or Commissioner ofCustoms as an international airport for customsservice.
b.A landing rights airport at which specific
permission to land must be obtained from customsauthorities in advance of contemplated use.
c.Airports designated under the Convention on
International Civil Aviation as an airport for use byinternational commercial air transport and/or interna-
tional general aviation.
(See ICAO term INTERNATIONAL AIRPORT.)
(Refer to Chart Supplement U.S .)
(Refer to IFIM.)
INTERNATIONAL AIRPORT [ICAO] − Any airport
designated by the Contracting State in whoseterritory it is situated as an airport of entry anddeparture for international air traffic, where theformalities incident to customs, immigration, publichealth, animal and plant quarantine and similarprocedures are carried out.
INTERNATIONAL CIVIL A VIATION ORGA-
NIZATION [ICAO] − A specialized agency of the
United Nations whose objective is to develop theprinciples and techniques of international airnavigation and to foster planning and development of
international civil air transport.
a.Regions include:
1.African-Indian Ocean Region
2.Caribbean Region
3.European Region
4.Middle East/Asia Region
5.North American Region
6.North Atlantic Region
7.Pacific Region
8.South American Region
INTERNATIONAL FLIGHT INFORMATION
MANUAL − A publication designed primarily as a
pilot’s preflight planning guide for flights intoforeign airspace and for flights returning to the U.S.from foreign locations.
Pilot/Controller Glossary 10/12/17
PCG I−6INTERROGATOR − The ground-based surveillance
radar beacon transmitter -receiver, which normally
scans in synchronism with a primary radar,transmitting discrete radio signals which repetitious-
ly request all transponders on the mode being used toreply. The replies received are mixed with theprimary radar returns and displayed on the same plan
position indicator (radar scope). Also, applied to theairborne element of the TACAN/DME system.
(See TRANSPONDER.)
(Refer to AIM.)
INTERSECTING RUNWAYS − Two or more
runways which cross or meet within their lengths.
(See INTERSECTION.)
INTERSECTION −
a.A point defined by any combination of courses,
radials, or bearings of two or more navigational aids.b.Used to describe the point where two runways,
a runway and a taxiway, or two taxiways cross ormeet.
INTERSECTION DEPARTURE − A departure from
any runway intersection except the end of the runway.
(See INTERSECTION.)
INTERSECTION T AKEOFF −
(See INTERSECTION DEPARTURE.)
IR−
(See IFR MILITARY TRAINING ROUTES.)
IRREGULAR SURFACE − A surface that is open for
use but not per regulations.
ISR– Indicates the confidence level of the track
requires 5NM separation. 3NM separation, 1 1/2NM
separation, and target resolution cannot be used.
Pilot/Controller Glossary10/12/17
PCG J−1J
JAMMING − Electronic or mechanical interference
which may disrupt the display of aircraft on radar orthe transmission/reception of radio communications/
navigation.
JET BLAST − Jet engine exhaust (thrust stream
turbulence).
(See WAKE TURBULENCE.)
JET ROUTE − A route designed to serve aircraft
operations from 18,000 feet MSL up to and including
flight level 450. The routes are referred to as “J”routes with numbering to identify the designatedroute; e.g., J105.
(See Class A AIRSPACE.)
(Refer to 14 CFR Part 71.)JET STREAM − A migrating stream of high-speed
winds present at high altitudes.
JETTISONING OF EXTERNAL STORES − Air-
borne release of external stores; e.g., tiptanks,ordnance.
(See FUEL DUMPING.)
(Refer to 14 CFR Part 91.)
JOINT USE RESTRICTED AREA −
(See RESTRICTED AREA.)
JUMP ZONE− The airspace directly associated with
a Drop Zone. Vertical and horizontal limits may belocally defined.
Pilot/Controller Glossary10/12/17
PCG K−1K
KNOWN TRAFFIC − With respect to ATC clear-
ances, means aircraft whose altitude, position, andintentions are known to ATC.
Pilot/Controller Glossary10/12/17
PCG L−1L
LAA−
(See LOCAL AIRPORT ADVISORY.)
LAAS−
(See LOW ALTITUDE ALERT SYSTEM.)
LAHSO− An acronym for “Land and Hold Short
Operation.” These operations include landing andholding short of an intersecting runway, a taxiway, apredetermined point, or an approach/departureflightpath.
LAHSO-DRY − Land and hold short operations on
runways that are dry.
LAHSO-WET − Land and hold short operations on
runways that are wet (but not contaminated).
LAND AND HOLD SHORT OPERATIONS −
Operations which include simultaneous takeoffs andlandings and/or simultaneous landings when alanding aircraft is able and is instructed by thecontroller to hold-short of the intersecting runway/taxiway or designated hold-short point. Pilots areexpected to promptly inform the controller if the hold
short clearance cannot be accepted.
(See PARALLEL RUNWAYS.)
(Refer to AIM.)
LANDING AREA − Any locality either on land,
water, or structures, including airports/heliports andintermediate landing fields, which is used, orintended to be used, for the landing and takeoff ofaircraft whether or not facilities are provided for theshelter, servicing, or for receiving or dischargingpassengers or cargo.
(See ICAO term LANDING AREA.)
LANDING AREA [ICAO] − That part of a movement
area intended for the landing or take-off of aircraft.
LANDING DIRECTION INDICATOR − A device
which visually indicates the direction in whichlandings and takeoffs should be made.
(See TETRAHEDRON.)
(Refer to AIM.)LANDING DISTANCE A V AILABLE (LDA) − The
runway length declared available and suitable for alanding airplane.
(See ICAO term LANDING DISTANCE
AVAILABLE.)
LANDING DISTANCE A VAILABLE [ICAO] − The
length of runway which is declared available andsuitable for the ground run of an aeroplane landing.
LANDING MINIMUMS − The minimum visibility
prescribed for landing a civil aircraft while using aninstrument approach procedure. The minimumapplies with other limitations set forth in 14 CFRPart 91 with respect to the Minimum DescentAltitude (MDA) or Decision Height (DH) prescribed
in the instrument approach procedures as follows:
a.Straight-in landing minimums. A statement of
MDA and visibility, or DH and visibility, required for
a straight-in landing on a specified runway, or
b.Circling minimums. A statement of MDA and
visibility required for the circle-to-land maneuver.
Note: Descent below the MDA or DH must meet the
conditions stated in 14 CFR Section 91.175.
(See CIRCLE-TO-LAND MANEUVER.)
(See DECISION HEIGHT.)(See INSTRUMENT APPROACH
PROCEDURE.)
(See MINIMUM DESCENT ALTITUDE.)(See STRAIGHT-IN LANDING.)(See VISIBILITY.)
(Refer to 14 CFR Part 91.)
LANDING ROLL − The distance from the point of
touchdown to the point where the aircraft can bebrought to a stop or exit the runway.
LANDING SEQUENCE − The order in which
aircraft are positioned for landing.
(See APPROACH SEQUENCE.)
LAST ASSIGNED ALTITUDE − The last altitude/
flight level assigned by ATC and acknowledged bythe pilot.
(See MAINTAIN.)
(Refer to 14 CFR Part 91.)
LATERAL NA VIGATION (LNA V)– A function of
area navigation (RNA V) equipment which calculates,
Pilot/Controller Glossary 10/12/17
PCG L−2displays, and provides lateral guidance to a profile or
path.
LATERAL SEPARATION − The lateral spacing of
aircraft at the same altitude by requiring operation on
different routes or in dif ferent geographical locations.
(See SEPARATION.)
LDA−
(See LOCALIZER TYPE DIRECTIONAL AID.)
(See LANDING DISTANCE AVAILABLE.)(See ICAO Term LANDING DISTANCE
AVAILABLE.)
LF−
(See LOW FREQUENCY.)
LIGHTED AIRPORT − An airport where runway and
obstruction lighting is available.
(See AIRPORT LIGHTING.)
(Refer to AIM.)
LIGHT GUN − A handheld directional light signaling
device which emits a brilliant narrow beam of white,
green, or red light as selected by the tower controller.The color and type of light transmitted can be used toapprove or disapprove anticipated pilot actions where
radio communication is not available. The light gunis used for controlling traffic operating in the vicinity
of the airport and on the airport movement area.
(Refer to AIM.)
LIGHT-SPORT AIRCRAFT (LSA)- AnFAA-registered aircraft, other than a helicopter orpowered-lift, that meets certain weight andperformance. Principally it is a single engine aircraft
with a maximum of two seats and weighing no morethan 1,430 pounds if intended for operation on water,
or 1,320 pounds if not. They must be of simple design(fixed landing gear (except if intended for operations
on water or a glider) piston powered,non-pressurized, with a fixed or ground adjustablepropeller), Performance is also limited to a maximum
airspeed in level flight of not more than 120 knotsCAS, have a maximum never-exceed speed of notmore than 120 knots CAS for a glider, and have amaximum stalling speed, without the use oflift-enhancing devices (VS1 ) of not more than45 knots CAS. They may be certificated as eitherExperimental LSA or as a Special LSA aircraft. A
minimum of a sport pilot
certificate is required to
operate light-sport aircraft.” (Refer to 14 CFR Part 1,
§1.1.)LINE UP AND WAIT (LUAW) − Used by ATC to
inform a pilot to taxi onto the departure runway to line
up and wait. It is not authorization for takeoff. It isused when takeoff clearance cannot immediately beissued because of traffic or other reasons.
(See CLEARED FOR TAKEOFF.)
LOCAL AIRPORT ADVISORY (LAA) − A service
available only in Alaska and provided by facilities,which are located on the landing airport, have adiscrete ground −to−air communication frequency or
the tower frequency when the tower is closed,automated weather reporting with voice broadcast-ing, and a continuous ASOS/AWSS/AWOS datadisplay, other continuous direct reading instruments,or manual observations available to the specialist.
(See AIRPORT ADVISORY AREA.)
LOCAL TRAFFIC − Aircraft operating in the traffic
pattern or within sight of the tower, or aircraft known
to be departing or arriving from flight in local practiceareas, or aircraft executing practice instrumentapproaches at the airport.
(See TRAFFIC PATTERN.)
LOCALIZER − The component of an ILS which
provides course guidance to the runway.
(See INSTRUMENT LANDING SYSTEM.)
(See ICAO term LOCALIZER COURSE.)
(Refer to AIM.)
LOCALIZER COURSE [ICAO] − The locus of
points, in any given horizontal plane, at which theDDM (difference in depth of modulation) is zero.
LOCALIZER OFFSET − An angular offset of the
localizer aligned with 3 /C0095 of the runway alignment.
LOCALIZER TYPE DIRECTIONAL AID − A
localizer with an angular offset that exceeds 3 /C0095. of the
runway alignment used for nonprecision instrumentapproaches with utility and accuracy comparable toa localizer but which are not part of a complete ILS.
(Refer to AIM.)
LOCALIZER TYPE DIRECTIONAL AID (LDA)PRECISION RUNWAY MONITOR (PRM)APPROACH − An approach, which includes a
glidslope, used in conjunction with an ILS PRM,RNA V PRM or GLS PRM approach to an adjacentrunway to conduct Simultaneous Offset InstrumentApproaches (SOIA) to parallel runways whosecenterlines are separated by less than 3,000 feet and
Pilot/Controller Glossary10/12/17
PCG L−3at least 750 feet. NTZ monitoring is required to
conduct these approaches.
(See SIMULTANEOUS OFFSET INSTRUMENT
APPROACH (SOIA).)
(Refer to AIM)
LOCALIZER USABLE DISTANCE − The maxi-
mum distance from the localizer transmitter at aspecified altitude, as verified by flight inspection, atwhich reliable course information is continuouslyreceived.
(Refer to AIM.)
LOCATOR [ICAO] − An LM/MF NDB used as an aid
to final approach.
Note: A locator usually has an average radius of
rated coverage of between 18.5 and 46.3 km (10and 25 NM).
LONG RANGE NA VIGA TION−
(See LORAN.)
LONGITUDINAL SEPARATION − The longitudi-
nal spacing of aircraft at the same altitude by aminimum distance expressed in units of time ormiles.
(See SEPARATION.)
(Refer to AIM.)
LORAN− An electronic navigational system by
which hyperbolic lines of position are determined by
measuring the difference in the time of reception ofsynchronized pulse signals from two fixed transmit-ters. Loran A operates in the 1750-1950 kHzfrequency band. Loran C and D operate in the100-110 kHz frequency band. In 2010, the U.S. Coast
Guard terminated all U.S. LORAN-C transmissions.
(Refer to AIM.)
LOST COMMUNICATIONS − Loss of the ability to
communicate by radio. Aircraft are sometimesreferred to as NORDO (No Radio). Standard pilotprocedures are specified in 14 CFR Part 91. Radarcontrollers issue procedures for pilots to follow in the
event of lost communications during a radar approach
when weather reports indicate that an aircraft willlikely encounter IFR weather conditions during theapproach.
(Refer to 14 CFR Part 91.)
(Refer to AIM.)LOST LINK − An interruption or loss of the control
link, or when the pilot is unable to effect control of the
aircraft and, as a result, the UA will perform apredictable or planned maneuver. Loss of command
and control link between the Control Station and theaircraft. There are two types of links:
a.An uplink which transmits command instruc-
tions to the aircraft, and
b.A downlink which transmits the status of the
aircraft and provides situational awareness to thepilot.
LOST LINK PROCEDURE − Preprogrammed or
predetermined mitigations to ensure the continuedsafe operation of the UA in the event of a lost link(LL). In the event positive link cannot be established,
flight termination must be implemented.
LOW ALTITUDE AIRWAY STRUCTURE − The
network of airways serving aircraft operations up tobut not including 18,000 feet MSL.
(See AIRWAY.)
(Refer to AIM.)
LOW ALTITUDE ALERT, CHECK YOUR ALTI-
TUDE IMMEDIATELY −
(See SAFETY ALERT.)
LOW APPROACH − An approach over an airport or
runway following an instrument approach or a VFRapproach including the go-around maneuver wherethe pilot intentionally does not make contact with the
runway.
(Refer to AIM.)
LOW FREQUENCY − The frequency band between
30 and 300 kHz.
(Refer to AIM.)
LPV− A type of approach with vertical guidance
(APV) based on WAAS, published on RNA V (GPS)approach charts. This procedure takes advantage ofthe precise lateral guidance available from WAAS.The minima is published as a decision altitude (DA).
LUAW−
(See LINE UP AND WAIT.)
Pilot/Controller Glossary10/12/17
PCG M−1M
MAA−
(See MAXIMUM AUTHORIZED ALTITUDE.)
MACH NUMBER − The ratio of true airspeed to the
speed of sound; e.g., MACH .82, MACH 1.6.
(See AIRSPEED.)
MACH TECHNIQUE [ICAO] − Describes a control
technique used by air traf fic control whereby turbojet
aircraft operating successively along suitable routesare cleared to maintain appropriate MACH numbersfor a relevant portion of the en route phase of flight.The principle objective is to achieve improvedutilization of the airspace and to ensure thatseparation between successive aircraft does notdecrease below the established minima.
MAHWP − Missed Approach Holding Waypoint
MAINTAIN −
a.Concerning altitude/flight level, the term
means to remain at the altitude/flight level specified.The phrase “climb and” or “descend and” normallyprecedes “maintain” and the altitude assignment;e.g., “descend and maintain 5,000.”
b.Concerning other ATC instructions, the term is
used in its literal sense; e.g., maintain VFR.
MAINTENANCE PLANNING FRICTION
LEVEL− The friction level specified in
AC 150/5320-12, Measurement, Construction, andMaintenance of Skid Resistant Airport PavementSurfaces, which represents the friction value belowwhich the runway pavement surface remainsacceptable for any category or class of aircraftoperations but which is beginning to show signs ofdeterioration. This value will vary depending on theparticular friction measurement equipment used.
MAKE SHORT APPROACH − Used by ATC to
inform a pilot to alter his/her traffic pattern so as tomake a short final approach.
(See TRAFFIC PATTERN.)
MAN PORTABLE AIR DEFENSE SYSTEMS(MANP ADS)− MANPADS are lightweight, shoul-
der−launched, missile systems used to bring down
aircraft and create mass casualties. The potential forMANPADS use against airborne aircraft is real andrequires familiarity with the subject. Terrorists
choose MANPADS because the weapons are lowcost, highly mobile, require minimal set −up time, and
are easy to use and maintain. Although the weaponshave limited range, and their accuracy is affected bypoor visibility and adverse weather, they can be fired
from anywhere on land or from boats where there isunrestricted visibility to the target.
MANDATORY ALTITUDE − An altitude depicted
on an instrument Approach Procedure Chartrequiring the aircraft to maintain altitude at thedepicted value.
MANPADS −
(See MAN PORTABLE AIR DEFENSE
SYSTEMS.)
MAP−
(See MISSED APPROACH POINT.)
MARKER BEACON − An electronic navigation
facility transmitting a 75 MHz vertical fan orboneshaped radiation pattern. Marker beacons areidentified by their modulation frequency and keyingcode, and when received by compatible airborneequipment, indicate to the pilot, both aurally andvisually, that he/she is passing over the facility.
(See INNER MARKER.)
(See MIDDLE MARKER.)
(See OUTER MARKER.)
(Refer to AIM.)
MARSA−
(See MILITARY AUTHORITY ASSUMES
RESPONSIBILITY FOR SEPARATION OF
AIRCRAFT.)
MAWP− Missed Approach Waypoint
MAXIMUM AUTHORIZED ALTITUDE − A pub-
lished altitude representing the maximum usablealtitude or flight level for an airspace structure orroute segment. It is the highest altitude on a Federalairway, jet route, area navigation low or high route,or other direct route for which an MEA is designatedin 14 CFR Part 95 at which adequate reception ofnavigation aid signals is assured.
MAYDAY − The international radiotelephony distress
signal. When repeated three times, it indicates
Pilot/Controller Glossary 10/12/17
PCG M−2imminent and grave danger and that immediate
assistance is requested.
(See PAN-PAN.)
(Refer to AIM.)
MCA−
(See MINIMUM CROSSING ALTITUDE.)
MDA−
(See MINIMUM DESCENT ALTITUDE.)
MEA−
(See MINIMUM EN ROUTE IFR ALTITUDE.)
MEARTS −
(See MICRO-EN ROUTE AUTOMATED RADAR
TRACKING SYSTEM.)
METEOROLOGICAL IMPACT STATEMENT −
An unscheduled planning forecast describingconditions expected to begin within 4 to 12 hourswhich may impact the flow of air traffic in a specific
center’s (ARTCC) area.
METER FIX ARC − A semicircle, equidistant from
a meter fix, usually in low altitude relatively close tothe meter fix, used to help CTAS/HOST calculate ameter time, and determine appropriate sector meterlist assignments for aircraft not on an establishedarrival route or assigned a meter fix.
METER FIX TIME/SLOT TIME − A calculated time
to depart the meter fix in order to cross the vertex atthe ACLT. This time reflects descent speedadjustment and any applicable time that must beabsorbed prior to crossing the meter fix.
METER LIST −
(See ARRIV AL SECTOR ADVISORY LIST.)
METER LIST DISPLAY INTERV AL − A dynamic
parameter which controls the number of minutesprior to the flight plan calculated time of arrival at the
meter fix for each aircraft, at which time the TCLT is
frozen and becomes an ACLT; i.e., the VTA isupdated and consequently the TCLT modified asappropriate until frozen at which time updating issuspended and an ACLT is assigned. When frozen,the flight entry is inserted into the arrival sector’smeter list for display on the sector PVD/MDM.MLDI is used if filed true airspeed is less than orequal to freeze speed parameters (FSPD).
METERING − A method of time-regulating arrival
traffic flow into a terminal area so as not to exceed apredetermined terminal acceptance rate.METERING AIRPORTS − Airports adapted for
metering and for which optimum flight paths aredefined. A maximum of 15 airports may be adapted.
METERING FIX − A fix along an established route
from over which aircraft will be metered prior toentering terminal airspace. Normally, this fix shouldbe established at a distance from the airport whichwill facilitate a profile descent 10,000 feet aboveairport elevation (AAE) or above.
METERING POSITION(S) − Adapted PVDs/
MDMs and associated “D” positions eligible fordisplay of a metering position list. A maximum offour PVDs/MDMs may be adapted.
METERING POSITION LIST − An ordered list of
data on arrivals for a selected metering airportdisplayed on a metering position PVD/MDM.
MFT−
(See METER FIX TIME/SLOT TIME.)
MHA−
(See MINIMUM HOLDING ALTITUDE.)
MIA−
(See MINIMUM IFR ALTITUDES.)
MICROBURST − A small downburst with outbursts
of damaging winds extending 2.5 miles or less. Inspite of its small horizontal scale, an intensemicroburst could induce wind speeds as high as 150knots
(Refer to AIM.)
MICRO-EN ROUTE AUTOMATED RADARTRACKING SYSTEM (MEARTS) − An automated
radar and radar beacon tracking system capable ofemploying both short-range (ASR) and long-range(ARSR) radars. This microcomputer driven systemprovides improved tracking, continuous data record-
ing, and use of full digital radar displays.
MID RVR −
(See VISIBILITY.)
MIDDLE COMPASS LOCATOR −
(See COMPASS LOCATOR.)
MIDDLE MARKER − A marker beacon that defines
a point along the glideslope of an ILS normallylocated at or near the point of decision height (ILSCategory I). It is keyed to transmit alternate dots and
dashes, with the alternate dots and dashes keyed at the
rate of 95 dot/dash combinations per minute on a
Pilot/Controller Glossary10/12/17
PCG M−31300 Hz tone, which is received aurally and visually
by compatible airborne equipment.
(See INSTRUMENT LANDING SYSTEM.)
(See MARKER BEACON.)
(Refer to AIM.)
MILES-IN-TRAIL − A specified distance between
aircraft, normally, in the same stratum associatedwith the same destination or route of flight.
MILITARY AUTHORITY ASSU MES RESPONSI-
BILITY FOR SEPARATION OF AIRCRAFT − A
condition whereby the military services involvedassume responsibility for separation betweenparticipating military aircraft in the A TC system. It is
used only for required IFR operations which arespecified in letters of agreement or other appropriate
FAA or military documents.
MILITARY LANDING ZONE − A landing strip used
exclusively by the military for training. A militarylanding zone does not carry a runway designation.
MILITARY OPERATIONS AREA −
(See SPECIAL USE AIRSPACE.)
MILITARY TRAINING ROUTES − Airspace of
defined vertical and lateral dimensions establishedfor the conduct of military flight training at airspeedsin excess of 250 knots IAS.
(See IFR MILITARY TRAINING ROUTES.)
(See VFR MILITARY TRAINING ROUTES.)
MINIMA −
(See MINIMUMS.)
MINIMUM CROSSING ALTITUDE − The lowest
altitude at certain fixes at which an aircraft must cross
when proceeding in the direction of a higherminimum en route IFR altitude (MEA).
(See MINIMUM EN ROUTE IFR ALTITUDE.)
MINIMUM DESCENT ALTITUDE − The lowest
altitude, expressed in feet above mean sea level, towhich descent is authorized on final approach orduring circle-to-land maneuvering in execution of astandard instrument approach procedure where noelectronic glideslope is provided.
(See NONPRECISION APPROACH
PROCEDURE.)
MINIMUM EN ROUTE IFR ALTITUDE (MEA) −
The lowest published altitude between radio fixeswhich assures acceptable navigational signal cover-
age and meets obstacle clearance requirementsbetween those fixes. The MEA prescribed for aFederal airway or segment thereof, area navigationlow or high route, or other direct route applies to theentire width of the airway , segment, or route between
the radio fixes defining the airway, segment, or route.
(Refer to 14 CFR Part 91.)
(Refer to 14 CFR Part 95.)
(Refer to AIM.)
MINIMUM FRICTION LEVEL − The friction level
specified in AC 150/5320-12, Measurement,Construction, and Maintenance of Skid ResistantAirport Pavement Surfaces, that represents theminimum recommended wet pavement surfacefriction value for any turbojet aircraft engaged inLAHSO. This value will vary with the particularfriction measurement equipment used.
MINIMUM FUEL − Indicates that an aircraft’s fuel
supply has reached a state where, upon reaching thedestination, it can accept little or no delay. This is not
an emergency situation but merely indicates anemergency situation is possible should any unduedelay occur.
(Refer to AIM.)
MINIMUM HOLDING ALTITUDE − The lowest
altitude prescribed for a holding pattern whichassures navigational signal coverage, communica-tions, and meets obstacle clearance requirements.
MINIMUM IFR ALTITUDES (MIA) − Minimum
altitudes for IFR operations as prescribed in 14 CFR
Part 91. These altitudes are published on aeronautical
charts and prescribed in 14 CFR Part 95 for airwaysand routes, and in 14 CFR Part 97 for standardinstrument approach procedures. If no applicableminimum altitude is prescribed in 14 CFR Part 95 or
14 CFR Part 97, the following minimum IFRaltitude applies:
a.In designated mountainous areas, 2,000 feet
above the highest obstacle within a horizontaldistance of 4 nautical miles from the course to beflown; or
b.Other than mountainous areas, 1,000 feet above
the highest obstacle within a horizontal distance of 4nautical miles from the course to be flown; or
Pilot/Controller Glossary 10/12/17
PCG M−4c.As otherwise authorized by the Administrator
or assigned by ATC.
(See MINIMUM CROSSING ALTITUDE.)
(See MINIMUM EN ROUTE IFR ALTITUDE.)(See MINIMUM OBSTRUCTION CLEARANCE
ALTITUDE.)
(See MINIMUM SAFE ALTITUDE.)(See MINIMUM VECTORING ALTITUDE.)
(Refer to 14 CFR Part 91.)
MINIMUM OBSTRUCTION CLEARANCE ALTI-
TUDE (MOCA) − The lowest published altitude in
effect between radio fixes on VOR airways,off-airway routes, or route segments which meets
obstacle clearance requirements for the entire routesegment and which assures acceptable navigationalsignal coverage only within 25 statute (22 nautical)miles of a VOR.
(Refer to 14 CFR Part 91.)
(Refer to 14 CFR Part 95.)
MINIMUM RECEPTION ALTITUDE − The lowest
altitude at which an intersection can be determined.
(Refer to 14 CFR Part 95.)
MINIMUM SAFE AL TITUDE−
a.The minimum altitude specified in 14 CFR
Part 91 for various aircraft operations.
b.Altitudes depicted on approach charts which
provide at least 1,000 feet of obstacle clearance foremergency use. These altitudes will be identified asMinimum Safe Altitudes or Emergency SafeAltitudes and are established as follows:
1.Minimum Safe Altitude (MSA). Altitudes
depicted on approach charts which provide at least1,000 feet of obstacle clearance within a 25-mileradius of the navigation facility, waypoint, or airportreference point upon which the MSA is predicated.MSAs are for emergency use only and do notnecessarily assure acceptable navigational signalcoverage.
(See ICAO term Minimum Sector Altitude.)
2.Emergency Safe Altitude (ESA). Altitudes
depicted on approach charts which provide at least1,000 feet of obstacle clearance in nonmountainousareas and 2,000 feet of obstacle clearance indesignated mountainous areas within a 100-mileradius of the navigation facility or waypoint used asthe ESA center. These altitudes are normally usedonly in military procedures and are identified onpublished procedures as “Emergency Safe
Altitudes.”
MINIMUM SAFE ALTITUDE WARNING − A
function of the ARTS III computer that aids thecontroller by alerting him/her when a tracked ModeC equipped aircraft is below or is predicted by thecomputer to go below a predetermined minimum safe
altitude.
(Refer to AIM.)
MINIMUM SECTOR ALTITUDE [ICAO] − The
lowest altitude which may be used under emergency
conditions which will provide a minimum clearanceof 300 m (1,000 feet) above all obstacles located inan area contained within a sector of a circle of 46 km(25 NM) radius centered on a radio aid to navigation.
MINIMUMS − Weather condition requirements
established for a particular operation or type ofoperation; e.g., IFR takeoff or landing, alternateairport for IFR flight plans, VFR flight, etc.
(See IFR CONDITIONS.)
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(See LANDING MINIMUMS.)(See VFR CONDITIONS.)(Refer to 14 CFR Part 91.)
(Refer to AIM.)
MINIMUM VECTORING ALTITUDE (MV A) −
The lowest MSL altitude at which an IFR aircraft will
be vectored by a radar controller, except as otherwiseauthorized for radar approaches, departures, andmissed approaches. The altitude meets IFR obstacleclearance criteria. It may be lower than the published
MEA along an airway or J-route segment. It may beutilized for radar vectoring only upon the controller’s
determination that an adequate radar return is beingreceived from the aircraft being controlled. Chartsdepicting minimum vectoring altitudes are normallyavailable only to the controllers and not to pilots.
(Refer to AIM.)
MINUTES-IN-TRAIL − A specified interval be-
tween aircraft expressed in time. This method wouldmore likely be utilized regardless of altitude.
MIS−
(See METEOROLOGICAL IMPACT
STATEMENT.)
MISSED APPROACH −
a.A maneuver conducted by a pilot when an
instrument approach cannot be completed to a
Pilot/Controller Glossary10/12/17
PCG M−5landing. The route of flight and altitude are shown on
instrument approach procedure charts. A pilotexecuting a missed approach prior to the MissedApproach Point (MAP) must continue along the final
approach to the MAP.
b.A term used by the pilot to inform ATC that
he/she is executing the missed approach.
c.At locations where ATC radar service is
provided, the pilot should conform to radar vectorswhen provided by ATC in lieu of the publishedmissed approach procedure.
(See MISSED APPROACH POINT.)
(Refer to AIM.)
MISSED APPROACH POINT − A point prescribed
in each instrument approach procedure at which amissed approach procedure shall be executed if therequired visual reference does not exist.
(See MISSED APPROACH.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
MISSED APPROACH PROCEDURE [ICAO] − The
procedure to be followed if the approach cannot becontinued.
MISSED APPROACH SEGMENT −
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
MLDI−
(See METER LIST DISPLAY INTERVAL.)
MM−
(See MIDDLE MARKER.)
MOA−
(See MILITARY OPERATIONS AREA.)
MOCA−
(See MINIMUM OBSTRUCTION CLEARANCE
ALTITUDE.)
MODE− The letter or number assigned to a specific
pulse spacing of radio signals transmitted or received
by ground interrogator or airborne transpondercomponents of the Air Traffic Control Radar Beacon
System (ATCRBS). Mode A (military Mode 3) andMode C (altitude reporting) are used in air traffic
control.
(See INTERROGATOR.)
(See RADAR.)
(See TRANSPONDER.)
(See ICAO term MODE.)(Refer to AIM.)
MODE (SSR MODE) [ICAO] − The letter or number
assigned to a specific pulse spacing of theinterrogation signals transmitted by an interrogator.There are 4 modes, A, B, C and D specified in Annex
10, corresponding to four different interrogationpulse spacings.
MODE C INTRUDER ALERT − A function of
certain air traf fic control automated systems designed
to alert radar controllers to existing or pendingsituations between a tracked target (known IFR orVFR aircraft) and an untracked target (unknown IFR
or VFR aircraft) that requires immediate attention/action.
(See CONFLICT ALERT.)
MODEL AIRCRAFT − An unmanned aircraft that is:
(1) capable of sustained flight in the atmosphere; (2)flown within visual line of sight of the personoperating the aircraft; and (3) flown for hobby orrecreational purposes.
MONITOR − (When used with communication
transfer) listen on a specific frequency and stand byfor instructions. Under normal circumstances do notestablish communications.
MONITOR ALERT (MA) − A function of the TFMS
that provides traffic management personnel with atool for predicting potential capacity problems inindividual operational sectors. The MA is anindication that traffic management personnel need to
analyze a particular sector for actual activity and todetermine the required action(s), if any, needed tocontrol the demand.
MONITOR ALERT PARAMETER (MAP) − The
number designated for use in monitor alertprocessing by the TFMS. The MAP is designated for
each operational sector for increments of 15 minutes.
MOSAIC/MULTI −SENSOR MODE − Accepts posi-
tional data from multiple radar or ADS −B sites.
Targets are displayed from a single source within aradar sort box according to the hierarchy of thesources assigned.
Pilot/Controller Glossary 10/12/17
PCG M−6MOVEMENT AREA − The runways, taxiways, and
other areas of an airport/heliport which are utilizedfor taxiing/hover taxiing, air taxiing, takeoff, andlanding of aircraft, exclusive of loading ramps andparking areas. At those airports/heliports with atower, specific approval for entry onto the movement
area must be obtained from ATC.
(See ICAO term MOVEMENT AREA.)
MOVEMENT AREA [ICAO] − That part of an
aerodrome to be used for the takeoff, landing andtaxiing of aircraft, consisting of the maneuvering area
and the apron(s).
MOVING TARGET INDICATOR − An electronic
device which will permit radar scope presentationonly from targets which are in motion. A partialremedy for ground clutter.
MRA−
(See MINIMUM RECEPTION ALTITUDE.)MSA−
(See MINIMUM SAFE ALTITUDE.)
MSAW−
(See MINIMUM SAFE ALTITUDE WARNING.)
MTI−
(See MOVING TARGET INDICATOR.)
MTR−
(See MILITARY TRAINING ROUTES.)
MULTICOM − A mobile service not open to public
correspondence used to provide communicationsessential to conduct the activities being performed by
or directed from private aircraft.
MULTIPLE RUNWAYS − The utilization of a
dedicated arrival runway(s) for departures and adedicated departure runway(s) for arrivals whenfeasible to reduce delays and enhance capacity.
MV A−
(See MINIMUM VECTORING ALTITUDE.)
Pilot/Controller Glossary10/12/17
PCG N−1N
NAS−
(See NATIONAL AIRSPACE SYSTEM.)
NAT HLA –
(See NORTH ATLANTIC HIGH LEVEL
AIRSPACE)
NATIONAL AIRSPACE SYSTEM − The common
network of U.S. airspace; air navigation facilities,equipment and services, airports or landing areas;aeronautical charts, information and services; rules,regulations and procedures, technical information,and manpower and material. Included are systemcomponents shared jointly with the military.
NATIONAL BEACON CODE ALLOCATION
PLAN AIRSPACE − Airspace over United States
territory located within the North American continent
between Canada and Mexico, including adjacentterritorial waters outward to about boundaries ofoceanic control areas (CTA)/Flight InformationRegions (FIR).
(See FLIGHT INFORMATION REGION.)
NATIONAL FLIGHT DATA CENTER − A facility in
Washington D.C., established by FAA to operate acentral aeronautical information service for thecollection, validation, and dissemination ofaeronautical data in support of the activities ofgovernment, industry, and the aviation community.The information is published in the National FlightData Digest.
(See NATIONAL FLIGHT DATA DIGEST.)
NATIONAL FLIGHT DATA DIGEST − A daily
(except weekends and Federal holidays) publicationof flight information appropriate to aeronauticalcharts, aeronautical publications, Notices to Airmen,
or other media serving the purpose of providingoperational flight data essential to safe and efficientaircraft operations.
NATIONAL SEARCH AND RESCUE PLAN − An
interagency agreement which provides for theeffective utilization of all available facilities in alltypes of search and rescue missions.
NAVAID−
(See NAVIGATIONAL AID.)NA V AID CLASSES − VOR, VORTAC, and T ACAN
aids are classed according to their operational use.The three classes of NA V AIDs are:
a.T− Terminal.
b.L− Low altitude.
c.H− High altitude.
Note: The normal service range for T, L, and H class
aids is found in the AIM. Certain operationalrequirements make it necessary to use some of
these aids at greater service ranges than
specified. Extended range is made possiblethrough flight inspection determinations. Someaids also have lesser service range due to location,
terrain, frequency protection, etc. Restrictions toservice range are listed in Chart Supplement U.S.
NA VIGABLE AIRSPACE − Airspace at and above
the minimum flight altitudes prescribed in the CFRsincluding airspace needed for safe takeoff andlanding.
(Refer to 14 CFR Part 91.)
NA VIGATION REFERENCE SYSTEM (NRS) −
The NRS is a system of waypoints developed for usewithin the United States for flight planning andnavigation without reference to ground basednavigational aids. The NRS waypoints are located in
a grid pattern along defined latitude and longitudelines. The initial use of the NRS will be in the highaltitude environment in conjunction with the HighAltitude Redesign initiative. The NRS waypoints are
intended for use by aircraft capable of point −to−point
navigation.
NA VIGATION SPECIFICATION [ICAO]− A set of
aircraft and flight crew requirements needed tosupport performance −based navigation operations
within a defined airspace. There are two kinds ofnavigation specifications:
a.RNP specification. A navigation specification
based on area navigation that includes therequirement for performance monitoring andalerting, designated by the prefix RNP; e.g., RNP 4,RNP APCH.
b.RNA V specification. A navigation specifica-
tion based on area navigation that does not include the
requirement for performance monitoring and alert-
Pilot/Controller Glossary 10/12/17
PCG N−2ing, designated by the prefix RNA V; e.g., RNA V 5,
RNA V 1.
Note: The Performance −based Navigation Manual
(Doc 9613), Volume II contains detailed guidanceon navigation specifications.
NA VIGATIONAL AID − Any visual or electronic
device airborne or on the surface which providespoint-to-point guidance information or position data
to aircraft in flight.
(See AIR NAVIGATION FACILITY.)
NBCAP AIRSPACE −
(See NATIONAL BEACON CODE ALLOCATION
PLAN AIRSPACE.)
NDB−
(See NONDIRECTIONAL BEACON.)
NEGA TIVE− “No,” or “permission not granted,” or
“that is not correct.”
NEGATIVE CONTACT − Used by pilots to inform
ATC that:
a.Previously issued traffic is not in sight. It may
be followed by the pilot’s request for the controller toprovide assistance in avoiding the traffic.
b.They were unable to contact ATC on a
particular frequency.
NFDC−
(See NATIONAL FLIGHT DATA CENTER.)
NFDD−
(See NATIONAL FLIGHT DATA DIGEST.)
NIGHT− The time between the end of evening civil
twilight and the beginning of morning civil twilight,as published in the Air Almanac, converted to localtime.
(See ICAO term NIGHT.)
NIGHT [ICAO] − The hours between the end of
evening civil twilight and the beginning of morningcivil twilight or such other period between sunset and
sunrise as may be specified by the appropriateauthority.
Note: Civil twilight ends in the evening when the
center of the sun’s disk is 6 degrees below thehorizon and begins in the morning when the center
of the sun’s disk is 6 degrees below the horizon.
NO GYRO APPROACH − A radar approach/vector
provided in case of a malfunctioning gyro-compassor directional gyro. Instead of providing the pilotwith h eadings to be flown, the controller observes the
radar track and issues control instructions “turnright/left” or “stop turn” as appropriate.
(Refer to AIM.)
NO GYRO VECTOR −
(See NO GYRO APPROACH.)
NO TRANSGRESSION ZONE (NTZ) − The NTZ is
a 2,000 foot wide zone, located equidistant betweenparallel runway or SOIA final approach courses inwhich flight is normally not allowed.
NONAPPROACH CONTROL TOWER − Author-
izes aircraft to land or takeof f at the airport controlled
by the tower or to transit the Class D airspace. Theprimary function of a nonapproach control tower isthe sequencing of aircraft in the traffic pattern and onthe landing area. Nonapproach control towers alsoseparate aircraft operating under instrument flightrules clearances from approach controls and centers.They provide ground control services to aircraft,vehicles, personnel, and equipment on the airportmovement area.
NONCOMMON ROUTE/POR TION− That segment
of a North American Route between the inlandnavigation facility and a designated North American
terminal.
NONCOMPOSITE SEPARATION − Separation in
accordance with minima other than the compositeseparation minimum specified for the area con-cerned.
NONDIRECTIONAL BEACON − An L/MF or UHF
radio beacon transm itting nondirectional signals
whereby the pilot of an aircraft equipped withdirection finding equipment can determine his/herbearing to or from the radio beacon and “home” on or
track to or from the station. When the radio beacon isinstalled in conjunction with the Instrument LandingSystem marker, it is normally called a CompassLocator.
(See AUTOMATIC DIRECTION FINDER.)
(See COMPASS LOCATOR.)
NONMOVEMENT AREAS − Taxiways and apron
(ramp) areas not under the control of air traffic.
NONPRECISION APPROACH −
(See NONPRECISION APPROACH
PROCEDURE.)
NONPRECISION APPROACH PROCEDURE − A
standard instrument approach procedure in which no
Pilot/Controller Glossary10/12/17
PCG N−3electronic glideslope is provided; e.g., VOR,
TACAN, NDB, LOC, ASR, LDA, or SDFapproaches.
NONRADAR − Precedes other terms and generally
means without the use of radar, such as:
a.Nonradar Approach. Used to describe
instrument approaches for which course guidance on
final approach is not provided by ground-basedprecision or surveillance radar. Radar vectors to thefinal approach course may or may not be provided by
ATC. Examples of nonradar approaches are VOR,NDB, TACAN, ILS, RNA V , and GLS approaches.
(See FINAL APPROACH COURSE.)
(See FINAL APPROACH-IFR.)
(See INSTRUMENT APPROACH
PROCEDURE.)
(See RADAR APPROACH.)
b.Nonradar Approach Control. An ATC facility
providing approach control service without the use of
radar.
(See APPROACH CONTROL FACILITY.)
(See APPROACH CONTROL SERVICE.)
c.Nonradar Arrival. An aircraft arriving at an
airport without radar service or at an airport served by
a radar facility and radar contact has not beenestablished or has been terminated due to a lack ofradar service to the airport.
(See RADAR ARRIVAL.)
(See RADAR SERVICE.)
d.Nonradar Route. A flight path or route over
which the pilot is performing his/her own navigation.
The pilot may be receiving radar separation, radarmonitoring, or other ATC services while on anonradar route.
(See RADAR ROUTE.)
e.Nonradar Separation. The spacing of aircraft in
accordance with established minima without the useof radar; e.g., vertical, lateral, or longitudinalseparation.
(See RADAR SEPARATION.)
NON−RESTRICTIVE ROUTING (NRR) − Portions
of a proposed route of flight where a user can flightplan the most advantageous flight path with norequirement to make reference to ground −based
NA V AIDs.
NOPAC−
(See NORTH PACIFIC.)NORDO (No Radio) − Aircraft that cannot or do not
communicate by radio when radio communication is
required are referred to as “NORDO.”
(See LOST COMMUNICATIONS.)
NORMAL OPERATING ZONE (NOZ) − The NOZ
is the operating zone within which aircraft flightremains during normal independent simultaneousparallel ILS approaches.
NORTH AMERICAN ROUTE − A numerically
coded route preplanned over existing airway androute systems to and from specific coastal fixesserving the North Atlantic. North American Routesconsist of the following:
a.Common Route/Portion. That segment of a
North American Route between the inland navigation
facility and the coastal fix.
b.Noncommon Route/Portion. That segment of a
North American Route between the inland navigation
facility and a designated North American terminal.
c.Inland Navigation Facility . A navigation aid on
a North American Route at which the common routeand/or the noncommon route begins or ends.
d.Coastal Fix. A navigation aid or intersection
where an aircraft transitions between the domesticroute structure and the oceanic route structure.
NORTH AMERICAN ROUTE PROGRAM (NRP)−
The NRP is a set of rules and procedures which aredesigned to increase the flexibility of user flightplanning within published guidelines.
NORTH ATLANTIC HIGH LEVEL AIRSPACE
(NAT HLA) − That volume of airspace (as defined in
ICAO Document 7030) between FL 285 and FL 420within the Oceanic Control Areas of Bodo Oceanic,Gander Oceanic, New Y ork Oceanic East, Reykjavik,
Santa Maria, and Shanwick, excluding the Shannonand Brest Ocean Transition Areas. ICAO Doc 007North Atlantic Operations and Airspace Manualprovides detailed information on related aircraft andoperational requirements.
NORTH MARK − A beacon data block sent by the
host computer to be displayed by the ARTS on a 360degree bearing at a locally selected radar azimuth and
distance. The North Mark is used to ensure correctrange/azimuth orientation during periods ofCENRAP.
NORTH PACIFIC − An organized route system
between the Alaskan west coast and Japan.
Pilot/Controller Glossary 10/12/17
PCG N−4NOT STANDARD − Varying from what is expected
or published. For use in NOTAMs only.
NOT STD -
(See NOT STANDARD)
NOTAM−
(See NOTICE TO AIRMEN.)
NOTAM [ICAO] − A notice containing information
concerning the establishment, condition or change in
any aeronautical facility, service, procedure orhazard, the timely knowledge of which is essential to
personnel concerned with flight operations.
a.I Distribution − Distribution by means of
telecommunication.
b.II Distribution − Distribution by means other
than telecommunications.
NOTICE TO AIRMEN − A notice containing
information (not known sufficiently in advance topublicize by other means) concerning theestablishment, condition, or change in anycomponent (facility, service, or procedure of, orhazard in the National Airspace System) the timelyknowledge of which is essential to personnelconcerned with flight operations.
NOTAM(D) − A NOTAM given (in addition to local
dissemination) distant dissemination beyond the areaof responsibility of the Flight Service Station. These
NOTAMs will be stored and available until canceled.
c.FDC NOTAM − A NOTAM regulatory in
nature, transmitted by USNOF and given systemwide dissemination.
(See ICAO term NOTAM.)
NOTICES TO AIRMEN PUBLICATION − A
publication issued every 28 days, designed primarily
for the pilot, which contains current NOTAMinformation considered essential to the safety offlight as well as supplemental data to otheraeronautical publications. The contraction NTAP isused in NOTAM text.
(See NOTICE TO AIRMEN.)
NRR−
(See NON −RESTRICTIVE ROUTING.)
NRS−
(See NAVIGATION REFERENCE SYSTEM.)
NTAP−
(See NOTICES TO AIRMEN PUBLICATION.)
NUMEROUS TARGETS VICINITY (LOCA-
TION)− A traffic advisory issued by ATC to advise
pilots that tar gets on the radar scope are too numerous
to issue individually.
(See TRAFFIC ADVISORIES.)
Pilot/Controller Glossary10/12/17
PCG O−1O
OBST ACLE− An existing object, object of natural
growth, or terrain at a fixed geographical location orwhich may be expected at a fixed location within aprescribed area with reference to which verticalclearance is or must be provided during flightoperation.
OBSTACLE DEP ARTURE PROCEDURE (ODP)−
A preplanned instrument flight rule (IFR) departureprocedure printed for pilot use in textual or graphicform to provide obstruction clearance via the leastonerous route from the terminal area to theappropriate en route structure. ODPs are recom-mended for obstruction clearance and may be flownwithout ATC clearance unless an alternate departureprocedure (SID or radar vector) has been specifically
assigned by ATC.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(See STANDARD INSTRUMENT
DEPARTURES.)
(Refer to AIM.)
OBSTACLE FREE ZONE − The OFZ is a three
dimensional volume of airspace which protects forthe transition of aircraft to and from the runway. TheOFZ clearing standard precludes taxiing and parkedairplanes and object penetrations, except forfrangible NA V AID locations that are fixed byfunction. Additionally, vehicles, equipment, andpersonnel may be authorized by air traffic control toenter the area using the provisions of FAA OrderJO 7110.65, Para 3 −1−5, Vehicles/Equipment/Per-
sonnal Near/On Runways. The runway OFZ and
when applicable, the inner-approach OFZ, and theinner-transitional OFZ, comprise the OFZ.
a.Runway OFZ. The runway OFZ is a defined
volume of airspace centered above the runway. Therunway OFZ is the airspace above a surface whoseelevation at any point is the same as the elevation ofthe nearest point on the runway centerline. Therunway OFZ extends 200 feet beyond each end of the
runway. The width is as follows:
1.For runways serving large airplanes, the
greater of:
(a)400 feet, or(b)180 feet, plus the wingspan of the most
demanding airplane, plus 20 feet per 1,000 feet ofairport elevation.
2.For runways serving only small airplanes:
(a)300 feet for precision instrument run-
ways.
(b)250 feet for other runways serving small
airplanes with approach speeds of 50 knots, or more.
(c)120 feet for other runways serving small
airplanes with approach speeds of less than 50 knots.
b.Inner-approach OFZ. The inner-approach OFZ
is a defined volume of airspace centered on theapproach area. The inner-approach OFZ applies only
to runways with an approach lighting system. Theinner-approach OFZ begins 200 feet from the runway
threshold at the same elevation as the runwaythreshold and extends 200 feet beyond the last lightunit in the approach lighting system. The width of the
inner-approach OFZ is the same as the runway OFZ
and rises at a slope of 50 (horizontal) to 1 (vertical)from the beginning.
c.Inner-transitional OFZ. The inner transitional
surface OFZ is a defined volume of airspace along the
sides of the runway and inner-approach OFZ andapplies only to precision instrument runways. Theinner-transitional surface OFZ slopes 3 (horizontal)to 1 (vertical) out from the edges of the runway OFZand inner-approach OFZ to a height of 150 feet abovethe established airport elevation.
(Refer to AC 150/5300-13, Chapter 3.)
(Refer to FAA Order JO 7110.65, Para 3 −1−5,
Vehicles/Equipment/Personnel Near/On
Runways.)
OBSTRUCTION − Any object/obstacle exceeding
the obstruction standards specified by 14 CFRPart 77, Subpart C.
OBSTRUCTION LIGHT − A light or one of a group
of lights, usually red or white, frequently mounted ona surface structure or natural terrain to warn pilots ofthe presence of an obstruction.
OCEANIC AIRSPACE − Airspace over the oceans of
the world, considered international airspace, whereoceanic separation and procedures per the Interna-tional Civil Aviation Organization are applied.Responsibility for the provisions of air traf fic control
Pilot/Controller Glossary 10/12/17
PCG O−2service in this airspace is delegated to various
countries, based generally upon geographic proxim-ity and the availability of the required resources.
OCEANIC ERROR REPORT − A report filed when
ATC observes an Oceanic Error as defined byFAAO 7110.82, Reporting Oceanic Errors.
OCEANIC PUBLISHED ROUTE − A route estab-
lished in international airspace and charted ordescribed in flight information publications, such asRoute Charts, DOD En route Charts, ChartSupplements, NOTAMs, and Track Messages.
OCEANIC TRANSITION ROUTE − An ATS route
established for the purpose of transitioning aircraftto/from an organized track system.
ODP−
(See OBSTACLE DEPARTURE PROCEDURE.)
OFF COURSE − A term used to describe a situation
where an aircraft has reported a position fix or isobserved on radar at a point not on the A TC-approved
route of flight.
OFF-ROUTE VECTOR − A vector by ATC which
takes an aircraft off a previously assigned route.Altitudes assigned by ATC during such vectorsprovide required obstacle clearance.
OFFSET PARA LLEL RUNWAYS − Staggered
runways having centerlines which are parallel.
OFFSHORE/CONTROL AIRSPACE AREA − That
portion of airspace between the U.S. 12 NM limit and
the oceanic CTA/FIR boundary within which airtraffic control is exercised. These areas areestablished to provide air traffic control services.Offshore/Control Airspace Areas may be classifiedas either Class A airspace or Class E airspace.
OFT−
(See OUTER FIX TIME.)
OM−
(See OUTER MARKER.)
ON COURSE −
a.Used to indicate that an aircraft is established on
the route centerline.b.Used by ATC to advise a pilot making a radar
approach that his/her aircraft is lined up on the finalapproach course.
(See ON-COURSE INDICATION.)
ON-COURSE INDICATION − An indication on an
instrument, which provides the pilot a visual meansof determining that the aircraft is located on thecenterline of a given navigational track, or anindication on a radar scope that an aircraft is on agiven track.
ONE-MINUTE WEATHER − The most recent one
minute updated weather broadcast received by a pilot
from an uncontrolled airport ASOS/AWSS/AWOS.
ONER−
(See OCEANIC NAVIGATIONAL ERROR
REPORT.)
OPERA TIONAL−
(See DUE REGARD.)
OPERATIONS SPECIFICATIONS [ICAO] − The
authorizations, conditions and limitations associated
with the air operator certificate and subject to theconditions in the operations manual.
OPPOSITE DIRECTION AIRCRAFT − Aircraft are
operating in opposite directions when:
a.They are following the same track in reciprocal
directions; or
b.Their tracks are parallel and the aircraft are
flying in reciprocal directions; or
c.Their tracks intersect at an angle of more than
135/C0095.
OPTION APPROACH − An approach requested and
conducted by a pilot which will result in either atouch-and-go, missed approach, low approach,stop-and-go, or full stop landing. Pilots should advise
ATC if they decide to remain on the runway, of anydelay in their stop and go, delay clearing the runway,
or are unable to comply with the instruction(s).
(See CLEARED FOR THE OPTION.)
(Refer to AIM.)
ORGANIZED TRACK SYSTEM − A series of ATS
routes which are fixed and charted; i.e., CEP,NOPAC, or flexible and described by NOTAM; i.e.,NAT TRACK MESSAGE.
Pilot/Controller Glossary10/12/17
PCG O−3OROCA− An off-route altitude which provides
obstruction clearance with a 1,000 foot buffer innon−mountainous terrain areas and a 2,000 foot
buffer in designated mountainous areas within theUnited States. This altitude may not provide signalcoverage from ground-based navigational aids, airtraffic control radar, or communications coverage.
OTR−
(See OCEANIC TRANSITION ROUTE.)
OTS−
(See ORGANIZED TRACK SYSTEM.)
OUT− The conversation is ended and no response is
expected.
OUT OF SERVICE − When a piece of equipment, a
system, a facility or a service is not operational,certified (if required) and immediately “available”for Air Traffic or public use.
OUTER AREA (associated with Class C airspace) −
Non−regulatory airspace surrounding designated
Class C airspace airports wherein ATC provides radar
vectoring and sequencing on a full-time basis for allIFR and participating VFR aircraft. The serviceprovided in the outer area is called Class C servicewhich includes: IFR/IFR −IFR separation; IFR/
VFR−traffic advisories and conflict resolution; and
VFR/VFR −traffic advisories and, as appropriate,
safety alerts. The normal radius will be 20 nauticalmiles with some variations based on site-specificrequirements. The outer area extends outward fromthe primary Class C airspace airport and extends fromthe lower limits of radar/radio coverage up to theceiling of the approach control’s delegated airspaceexcluding the Class C charted area and other airspace
as appropriate.
(See CONFLICT RESOLUTION.)
(See CONTROLLED AIRSPACE.)
OUTER COMPASS LOCATOR −
(See COMPASS LOCATOR.)
OUTER FIX − A general term used within ATC to
describe fixes in the terminal area, other than the final
approach fix. Aircraft are normally cleared to thesefixes by an Air Route Traffic Control Center or anApproach Control Facility. Aircraft are normallycleared from these fixes to the final approach fix orfinal approach course.
OROUTER FIX − An adapted fix along the converted
route of flight, prior to the meter fix, for whichcrossing times are calculated and displayed in themetering position list.
OUTER FIX ARC − A semicircle, usually about a
50−70 mile radius from a meter fix, usually in high
altitude, which is used by CTAS/HOST to calculateouter fix times and determine appropriate sectormeter list assignments for aircraft on an establishedarrival route that will traverse the arc.
OUTER FIX TIME − A calculated time to depart the
outer fix in order to cross the vertex at the ACLT. The
time reflects descent speed adjustments and anyapplicable delay time that must be absorbed prior tocrossing the meter fix.
OUTER MARKER − A marker beacon at or near the
glideslope intercept altitude of an ILS approach. It iskeyed to transmit two dashes per second on a 400 Hz
tone, which is received aurally and visually bycompatible airborne equipment. The OM is normally
located four to seven miles from the runway threshold
on the extended centerline of the runway.
(See INSTRUMENT LANDING SYSTEM.)
(See MARKER BEACON.)(Refer to AIM.)
OVER− My transmission is ended; I expect a
response.
OVERHEAD MANEUVER − A series of predeter-
mined maneuvers prescribed for aircraft (often information) for entry into the visual flight rules (VFR)
traffic pattern and to proceed to a landing. Anoverhead maneuver is not an instrument flight rules(IFR) approach procedure. An aircraft executing anoverhead maneuver is considered VFR and the IFRflight plan is cancelled when the aircraft reaches the“initial point” on the initial approach portion of themaneuver. The pattern usually specifies thefollowing:
a.The radio contact required of the pilot.
b.The speed to be maintained.
c.An initial approach 3 to 5 miles in length.
d.An elliptical pattern consisting of two 180
degree turns.
e.A break point at which the first 180 degree turn
is started.
f.The direction of turns.
g.Altitude (at least 500 feet above the convention-
al pattern).
Pilot/Controller Glossary 10/12/17
PCG O−4h.A “Roll-out” on final approach not less than 1/4
mile from the landing threshold and not less than 300
feet above the ground.OVERLYING CENTER − The ARTCC facility that
is responsible for arrival/departure operations at aspecific terminal.
Pilot/Controller Glossary10/12/17
PCG P−1P
P TIME−
(See PROPOSED DEPARTURE TIME.)
P-ACP−
(See PREARRANGED COORDINATION
PROCEDURES.)
PAN-PAN − The international radio-telephony urgen-
cy signal. When repeated three times, indicatesuncertainty or alert followed by the nature of theurgency.
(See MAYDAY.)
(Refer to AIM.)
PAR−
(See PRECISION APPROACH RADAR.)
PAR [ICAO] −
(See ICAO Term PRECISION APPROACH
RADAR.)
PARALLEL ILS APPROACHES − Approaches to
parallel runways by IFR aircraft which, whenestablished inbound toward the airport on theadjacent final approach courses, are radar-separated
by at least 2 miles.
(See FINAL APPROACH COURSE.)
(See SIMULTANEOUS ILS APPROACHES.)
PARALLEL OFFSET ROUTE − A parallel track to
the left or right of the designated or establishedairway/route. Normally associated with Area Navi-gation (RNA V) operations.
(See AREA NAVIGATION.)
PARALLEL RUNWAYS − Two or more runways at
the same airport whose centerlines are parallel. Inaddition to runway number, parallel runways aredesignated as L (left) and R (right) or , if three parallel
runways exist, L (left), C (center), and R (right).
PBCT−
(See PROPOSED BOUNDARY CROSSING
TIME.)
PBN
(See ICAO Term PERFORMANCE −BASED
NAVIGATION.)
PDC−
(See PRE−DEPARTURE CLEARANCE .)PERFORMANCE −BASED NA VIGATION (PBN)
[ICAO]− Area navigation based on performance
requirements for aircraft operating along an ATSroute, on an instrument approach procedure or in adesignated airspace.
Note: Performance requirements are expressed in
navigation specifications (RNAV specification,RNP specification) in terms of accuracy, integrity,continuity, availability, and functionality needed for
the proposed operation in the context of a
particular airspace concept.
PERMANENT ECHO− Radar signals reflected from
fixed objects on the earth’s surface; e.g., buildings,towers, terrain. Permanent echoes are distinguishedfrom “ground clutter” by being definable locationsrather than large areas. Under certain conditions they
may be used to check radar alignment.
PHOTO RECONNAISSANCE − Military activity
that requires locating individual photo targets andnavigating to the targets at a preplanned angle andaltitude. The activity normally requires a lateral route
width of 16 NM and altitude range of 1,500 feet to10,000 feet AGL.
PILOT BRIEFING − A service provided by the FSS
to assist pilots in flight planning. Briefing items mayinclude weather information, NOTAMS, militaryactivities, flow control information, and other itemsas requested.
(Refer to AIM.)
PILOT IN COMMAND − The pilot responsible for
the operation and safety of an aircraft during flighttime.
(Refer to 14 CFR Part 91.)
PILOT WEATHER REPORT − A report of meteoro-
logical phenomena encountered by aircraft in flight.
(Refer to AIM.)
PILOT’S DISCRETION − When used in conjunc-
tion with altitude assignments, means that ATC hasoffered the pilot the option of starting climb ordescent whenever he/she wishes and conducting theclimb or descent at any rate he/she wishes. He/shemay temporarily level off at any intermediatealtitude. However, once he/she has vacated analtitude, he/she may not return to that altitude.
Pilot/Controller Glossary 10/12/17
PCG P−2PIREP−
(See PILOT WEATHER REPORT.)
PITCH POINT − A fix/waypoint that serves as a
transition point from a departure procedure or the low
altitude ground −based navigation structure into the
high altitude waypoint system.
PLANS DISPLAY − A display available in EDST
that provides detailed flight plan and predictedconflict information in textual format for requestedCurrent Plans and all Trial Plans.
(See EN ROUTE DECISION SUPPORT TOOL)
POFZ−
(See PRECISION OBSTACLE FREE ZONE.)
POINT OUT −
(See RADAR POINT OUT.)
POINT−TO−POINT (PTP) − A level of NRR service
for aircraft that is based on traditional waypoints intheir FMSs or RNA V equipage.
POLAR TRACK STRUCTURE − A system of
organized routes between Iceland and Alaska whichoverlie Canadian MNPS Airspace.
POSITION REPORT − A report over a known
location as transmitted by an aircraft to ATC.
(Refer to AIM.)
POSITION SYMBOL − A computer-generated
indication shown on a radar display to indicate themode of tracking.
POSITIVE CONTROL − The separation of all air
traffic within designated airspace by air trafficcontrol.
PRACTICE INSTRUMENT APPROACH − An
instrument approach procedure conducted by a VFR
or an IFR aircraft for the purpose of pilot training orproficiency demonstrations.
PRE−DEPARTURE CLEARANCE − An application
with the Terminal Data Link System (TDLS) thatprovides clearance information to subscribers,through a service provider, in text to the cockpit orgate printer.PREARRANGED COORDINATION − A standard-
ized procedure which permits an air traf fic controller
to enter the airspace assigned to another air trafficcontroller without verbal coordination. The proce-dures are defined in a facility directive which ensures
approved separation between aircraft.
PREARRANGED COORDINATION PROCE-
DURES− A facility’s standardized procedure that
describes the process by which one controller shallallow an aircraft to penetrate or transit anothercontroller’s airspace in a manner that assuresapproved separation without individual coordination
for each aircraft.
PRECIPITATION − Any or all forms of water
particles (rain, sleet, hail, or snow) that fall from theatmosphere and reach the surface.
PRECIPITATION RADAR WEATHER DESCRIP-
TIONS− Existing radar systems cannot detect
turbulence. However, there is a direct correlationbetween the degree of turbulence and other weatherfeatures associated with thunderstorms and theweather radar precipitation intensity . Controllers will
issue (where capable) precipitation intensity asobserved by radar when using weather and radarprocessor (WARP) or NAS ground based digitalradars with weather capabilities. When precipitationintensity information is not available, the intensitywill be described as UNKNOWN. When intensitylevels can be determined, they shall be described as:
a.LIGHT (< 26 dBZ)
b.MODERATE (26 to 40 dBZ)
c.HEA VY (> 40 to 50 dBZ)
d.EXTREME (> 50 dBZ)
(Refer to AC 00 −45, Aviation Weather Services.)
PRECISION APPROACH −
(See PRECISION APPROACH PROCEDURE.)
PRECISION APPROACH PROCEDURE − A
standard instrument approach procedure in which an
electronic glideslope/or other type of glidepath isprovided ; e.g., ILS, PAR, and GLS.
(See INSTRUMENT LANDING SYSTEM.)
(See PRECISION APPROACH RADAR.)
Pilot/Controller Glossary10/12/17
PCG P−3PRECISION APPROACH RADAR − Radar equip-
ment in some ATC facilities operated by the FAAand/or the military services at joint-use civil/military
locations and separate military installations to detectand display azimuth, elevation, and range of aircrafton the final approach course to a runway. Thisequipment may be used to monitor certain non −radar
approaches, but is primarily used to conduct aprecision instrument approach (PAR) wherein thecontroller issues guidance instructions to the pilotbased on the aircraft’s position in relation to the final
approach course (azimuth), the glidepath (elevation),
and the distance (range) from the touchdown point onthe runway as displayed on the radar scope.
Note: The abbreviation “PAR” is also used to
denote preferential arrival routes in ARTCC
computers.
(See GLIDEPATH.)
(See PAR.)(See PREFERENTIAL ROUTES.)(See ICAO term PRECISION APPROACH
RADAR.)
(Refer to AIM.)
PRECISION APPROACH RADAR [ICAO] − Pri-
mary radar equipment used to determine the position
of an aircraft during final approach, in terms of lateraland vertical deviations relative to a nominal approachpath, and in range relative to touchdown.
Note: Precision approach radars are designed to
enable pilots of aircraft to be given guidance by
radio communication during the final stages of the
approach to land.
PRECISION OBSTACLE FREE ZONE (POFZ) −
An 800 foot wide by 200 foot long area centered onthe runway centerline adjacent to the thresholddesigned to protect airc raft flying precision
approaches from ground vehicles and other aircraftwhen ceiling is less than 250 feet or visibility is lessthan 3/4 statute mile (or runway visual range below4,000 feet.)
PRECISION RUNWAY MONITOR (PRM)
SYSTEM − Provides air traffic controllers
monitoring the NTZ during simultaneous closeparallel PRM approaches with precision, high update
rate secondary surveillance data. The high update rate
surveillance sensor component of the PRM system is
only required for specific runway or approach courseseparation. The high resolution color monitoringdisplay, Final Monitor Aid (FMA) of the PRMsystem, or other FMA with the same capability,
presents (NTZ) surveillance track data to controllersalong with detailed maps depicting approaches andno transgression zone and is required for allsimultaneous close parallel PRM NTZ monitoringoperations.
(Refer to AIM)
PREDICTIVE WIND SHEAR ALERT SYSTEM(PWS)− A self−contained system used onboard some
aircraft to alert the flight crew to the presence of apotential w ind shear. PWS systems typically monitor
3 miles ahead and 25 degrees left and right of theaircraft’s heading at or below 1200’ AGL. Departing
flights may receive a wind shear alert after they startthe takeoff roll and may elect to abort the takeoff.Aircraft on approach receiving an alert may elect togo around or perform a wind shear escape maneuver.
PREFERENTIAL ROUTES − Preferential routes
(PDRs, PARs, and PDARs) are adapted in ARTCCcomputers to accomplish inter/intrafacility controller
coordination and to assure that flight data is posted at
the proper control positions. Locations having a needfor these specific inbound and outbound routesnormally publish such routes in local facilitybulletins, and their use by pilots minimizes flightplan route amendments. When the workload or traffic
situation permits, controllers normally provide radar
vectors or assign requested routes to minimizecircuitous routing. Preferential routes are usuallyconfined to one AR TCC’s area and are referred to by
the following names or acronyms:
a.Preferential Departure Route (PDR). A specific
departure route from an airport or terminal area to an
en route point where there is no further need for flowcontrol. It may be included in an InstrumentDeparture Procedure (DP) or a Preferred IFR Route.
b.Preferential Arrival Route (PAR). A specific
arrival route from an appropriate en route point to an
airport or terminal area. It may be included in aStandard T erminal Arrival (ST AR) or a Preferred IFR
Route. The abbreviation “PAR” is used primarilywithin the ARTCC and should not be confused withthe abbreviation for Precision Approach Radar.
c.Preferential Departure and Arrival Route
(PDAR). A route between two terminals which arewithin or immediately adjacent to one AR TCC’s area.
PDARs are not synonymous with Preferred IFRRoutes but may be listed as such as they doaccomplish essentially the same purpose.
(See PREFERRED IFR ROUTES.)
Pilot/Controller Glossary 10/12/17
PCG P−4PREFERRED IFR ROUTES − Routes established
between busier airports to increase system ef ficiency
and capacity. They normally extend through one ormore ARTCC areas and are designed to achievebalanced traffic flows among high density terminals.
IFR clearances are issued on the basis of these routesexcept when severe weather avoidance procedures orother factors dictate otherwise. Preferred IFR Routesare listed in the Chart Supplement U.S. If a flight isplanned to or from an area having such routes but the
departure or arrival point is not listed in the ChartSupplement U.S., pilots may use that part of aPreferred IFR Route which is appropriate for thedeparture or arrival point that is listed. Preferred IFR
Routes are correlated with DPs and STARs and maybe defined by airways, jet routes, direct routesbetween NA V AIDs, Waypoints, NA V AID radials/DME, or any combinations thereof.
(See CENTER’S AREA.)
(See INSTRUMENT DEPARTURE
PROCEDURE.)
(See PREFERENTIAL ROUTES.)(See STANDARD TERMINAL ARRIVAL.)
(Refer to
CHART SUPPLEMENT U.S. )
(Refer to NOTICES TO AIRMEN PUBLICATION.)
PRE-FLIGHT PILOT BRIEFING −
(See PILOT BRIEFING.)
PREVAILING VISIBILITY −
(See VISIBILITY.)
PRIMARY RADAR TARGET − An analog or digital
target, exclusive of a secondary radar target,presented on a radar display.
PRM−
(See ILS PRM APPROACH and PRECISION
RUNWAY MONITOR SYSTEM.)
PROCEDURAL CONTROL [ICAO]– Term used to
indicate that information derived from an ATSsurveillance system is not required for the provisionof air traffic control service.
PROCEDURAL SEPARA TION [ICAO]– The sepa-
ration used when providing procedural control.
PROCEDURE TURN − The maneuver prescribed
when it is necessary to reverse direction to establishan aircraft on the intermediate approach segment orfinal approach course. The outbound course,direction of tu rn, distance within which the turn must
be completed, and minimum altitude are specified inthe procedure. However, unless otherwise restricted,
the point at which the turn may be commenced andthe type and rate of turn are left to the discretion of thepilot.
(See ICAO term PROCEDURE TURN.)
PROCEDURE TURN [ICAO] − A maneuver in
which a turn is made away from a designated trackfollowed by a turn in the opposite direction to permit
the aircraft to intercept and proceed along thereciprocal of the designated track.
Note 1: Procedure turns are designated “left” or
“right” according to the direction of the initial turn.
Note 2: Procedure turns may be designated as
being made either in level flight or while
descending, according to the circumstances of
each individual approach procedure.
PROCEDURE TURN INBOUND − That point of a
procedure turn maneuver where course reversal hasbeen completed and an aircraft is established inbound
on the intermediate approach segment or finalapproach course. A report of “procedure turninbound” is normally used by ATC as a positionreport for separation purposes.
(See FINAL APPROACH COURSE.)
(See PROCEDURE TURN.)
(See SEGMENTS OF AN INSTRUMENT
APPROACH PROCEDURE.)
PROFILE DESCENT − An uninterrupted descent
(except where level flight is required for speedadjustment; e. g., 250 knots at 10,000 feet MSL) from
cruising altitude/level to interception of a glideslopeor to a minimum altitude specified for the initial orintermediate approach segment of a nonprecisioninstrument approach. The profile descent normallyterminates at the approach gate or where theglideslope or other appropriate minimum altitude isintercepted.
PROGRESS REPORT −
(See POSITION REPORT.)
PROGRESSIVE TAXI − Precise taxi instructions
given to a pilot unfamiliar with the airport or issuedin stages as the aircraft proceeds along the taxi route.
PROHIBITED AREA−
(See SPECIAL USE AIRSPACE.)
(See ICAO term PROHIBITED AREA.)
PROHIBITED AREA [ICAO] − An airspace of
defined dimensions, above the land areas or territorial
waters of a State, within which the flight of aircraftis prohibited.
Pilot/Controller Glossary10/12/17
PCG P−5PROMINENT OBSTACLE– An obstacle that meets
one or more of the following conditions:
a.An obstacle which stands out beyond the
adjacent surface of surrounding terrain and immedi-ately projects a noticeable hazard to aircraft in flight.
b.An obstacle, not characterized as low and close
in, whose height is no less than 300 feet above thedeparture end of takeoff runway (DER) elevation, iswithin 10NM from the DER, and that penetrates that
airport/heliport’s diverse departure obstacle clear-ance surface (OCS).
c.An obstacle beyond 10NM from an airport/heli-
port that requires an obstacle departure procedure(ODP) to ensure obstacle avoidance.
(See OBSTACLE.)
(See OBSTRUCTION.)
PROPOSED BOUNDARY CROSSING TIME −
Each center has a PBCT parameter for each internalairport. Proposed internal flight plans are transmitted
to the adjacent center if the flight time along theproposed route from the departure airport to thecenter boundary is less than or equal to the value ofPBCT or if airport adaptation specifies transmissionregardless of PBCT.
PROPOSED DEPAR TURE TIME − The time that the
aircraft expects to become airborne.
PROTECTED AIRSPACE − The airspace on either
side of an oceanic route/track that is equal to one-halfthe lateral separation minimum except where
reduction of protected airspace has been authorized.
PROTECTED SEGMENT- The protected segment is
a segment on the amended TFM route that is to beinhibited from automatic adapted route alteration byERAM.
PT−
(See PROCEDURE TURN.)
PTP−
(See POINT −TO−POINT.)
PTS−
(See POLAR TRACK STRUCTURE.)
PUBLISHED INSTRUMENT APPROACH
PROCEDURE VISUAL SEGMENT − A segment on
an IAP chart annotated as “Fly Visual to Airport” or“Fly Visual.” A dashed arrow will indicate the visual
flight path on the profile and plan view with anassociated note on the approximate heading anddistance. The visual segment should be flown as adead reckoning course while maintaining visualconditions.
PUBLISHED ROUTE − A route for which an IFR
altitude has been established and published; e.g.,Federal Airways, Jet Routes, Area NavigationRoutes, Specified Direct Routes.
PWS−
(See PREDICTIVE WIND SHEAR ALERT
SYSTEM.)
Pilot/Controller Glossary10/12/17
PCG Q−1Q
Q ROUTE − ‘Q’ is the designator assigned to
published RNA V routes used by the United States.
QNE− The barometric pressure used for the standard
altimeter setting (29.92 inches Hg.).
QNH− The barometric pressure as reported by a
particular station.
QUADRANT − A quarter part of a circle, centered on
a NA V AID, oriented clockwise from magnetic northas follows: NE quadrant 000-089, SE quadrant
090-179, SW quadrant 180-269, NW quadrant270-359.
QUEUING −
(See STAGING/QUEUING.)
QUICK LOOK − A feature of the EAS and ARTS
which provides the controller the capability todisplay full data blocks of tracked aircraft from other
control positions.
Pilot/Controller Glossary10/12/17
PCG R−1R
RADAR− A device which, by measuring the time
interval between transmission and reception of radio
pulses and correlating the angular orientation of theradiated antenna beam or beams in azimuth and/orelevation, provides information on range, azimuth,and/or elevation of objects in the path of thetransmitted pulses.
a.Primary Radar − A radar system in which a
minute portion of a radio pulse transmitted from a site
is reflected by an object and then received back at thatsite for processing and display at an air traf fic control
facility.
b.Secondary Radar/Radar Beacon (ATCRBS) − A
radar system in which the object to be detected isfitted with cooperative equipment in the form of aradio receiver/transm itter (transponder). Radar
pulses transmitted from the searching transmitter/re-ceiver (interrogator) site are received in thecooperative equipment and used to trigger adistinctive transmission from the transponder. Thisreply transmission, rather than a reflected signal, isthen received back at the transmitter/receiver site forprocessing and display at an air traf fic control facility.
(See INTERROGATOR.)
(See TRANSPONDER.)
(See ICAO term RADAR.)
(Refer to AIM.)
RADAR [ICAO] − A radio detection device which
provides information on range, azimuth and/orelevation of objects.
a.Primary Radar − Radar system which uses
reflected radio signals.
b.Secondary Radar − Radar system wherein a
radio signal transmitted from a radar station initiatesthe transmission of a radio signal from anotherstation.
RADAR ADVISORY − The provision of advice and
information based on radar observations.
(See ADVISORY SERVICE.)
RADAR AL TIMETER −
(See RADIO ALTIMETER.)RADAR APPROACH − An instrument approach
procedure which utilizes Precision Approach Radar(PAR) or Airport Surveillance Radar (ASR).
(See AIRPORT SURVEILLANCE RADAR.)
(See INSTRUMENT APPROACH
PROCEDURE.)
(See PRECISION APPROACH RADAR.)
(See SURVEILLANCE APPROACH.)
(See ICAO term RADAR APPROACH.)(Refer to AIM.)
RADAR APPROACH [ICAO] − An approach,
executed by an aircraft, under the direction of a radar
controller.
RADAR APPROACH CONTROL FACILITY − A
terminal ATC facility that uses radar and nonradarcapabilities to provide approach control services toaircraft arriving, departing, or transiting airspacecontrolled by the facility.
(See APPROACH CONTROL SERVICE.)
a.Provides radar ATC services to aircraft
operating in the vicinity of one or more civil and/ormilitary airports in a terminal area. The facility mayprovide services of a ground controlled approach(GCA); i.e., ASR and PAR approaches. A radarapproach control facility may be operated by FAA,USAF, US Army, USN, USMC, or jointly by FAAand a military service. Specific facility nomencla-tures are used for administrative purposes only andare related to the physical location of the facility andthe operating service generally as follows:
1.Army Radar Approach Control (ARAC)
(Army).
2.Radar Air Traffic Control Facility (RATCF)
(Navy/FAA).
3.Radar Approach Control (RAPCON) (Air
Force/FAA).
4.Terminal Radar Approach Control
(TRACON) (FAA).
5.Air Traffic Control Tower (ATCT) (FAA).
(Only those towers delegated approach controlauthority.)
RADAR ARRIV AL − An aircraft arriving at an
airport served by a radar facility and in radar contact
with the facility.
(See NONRADAR.)
Pilot/Controller Glossary 10/12/17
PCG R−2RADAR BEACON −
(See RADAR.)
RADAR CLUTTER [ICAO] − The visual indication
on a radar display of unwanted signals.
RADAR CONTACT −
a.Used by ATC to inform an aircraft that it is
identified using an approved ATC surveillancesource on an air traffic controller’s display and thatradar flight following will be provided until radarservice is terminated. Radar service may also beprovided within the limits of necessity and capability.
When a pilot is informed of “radar contact,” he/sheautomatically discontinues reporting over compuls-ory reporting points.
(See ATC SURVEILLANCE SOURCE.)
(See RADAR CONTACT LOST.)(See RADAR FLIGHT FOLLOWING.)(See RADAR SERVICE.)(See RADAR SERVICE TERMINATED.)(Refer to AIM.)
b.The term used to inform the controller that the
aircraft is identified and approval is granted for theaircraft to enter the receiving controllers airspace.
(See ICAO term RADAR CONTACT.)
RADAR CONTACT [ICAO] − The situation which
exists when the radar blip or radar position symbol of
a particular aircraft is seen and identified on a radar
display.
RADAR CONT ACT LOST − Used by ATC to inform
a pilot that the surveil lance data used to determine the
aircraft’s position is no longer being received, or is no
longer reliable and radar service is no longer beingprovided. The loss may be attributed to severalfactors including the aircraft mer ging with weather or
ground clutter, the aircraft operating below radar line
of sight coverage, the aircraft entering an area of poorradar return, failure of the aircraft’s equipment, orfailure of the surveillance equipment.
(See CLUTTER.)
(See RADAR CONTACT.)
RADAR ENVIRONMENT − An area in which radar
service may be provided.
(See ADDITIONAL SERVICES.)
(See RADAR CONTACT.)(See RADAR SERVICE.)(See TRAFFIC ADVISORIES.)RADAR FLIGHT FOLLOWING − The observation
of the progress of radar identified aircraft, whoseprimary navigation is being provided by the pilot,wherein the controller retains and correlates theaircraft identity with the appropriate target or targetsymbol displayed on the radar scope.
(See RADAR CONTACT.)
(See RADAR SERVICE.)(Refer to AIM.)
RADAR IDENTIFICATION − The process of
ascertaining that an observed radar target is the radar
return from a particular aircraft.
(See RADAR CONTACT.)
(See RADAR SERVICE.)
RADAR IDENTIFIED AIRCRAFT − An aircraft, the
position of which has been correlated with anobserved target or symbol on the radar display.
(See RADAR CONTACT.)
(See RADAR CONTACT LOST.)
RADAR MONIT ORING−
(See RADAR SERVICE.)
RADAR NA VIGATIONAL GUIDANCE −
(See RADAR SERVICE.)
RADAR POINT OUT − An action taken by a
controller to transfer the radar identification of anaircraft to another controller if the aircraft will or may
enter the airspace or protected airspace of anothercontroller and radio communications will not betransferred.
RADAR REQUIRED − A term displayed on charts
and approach plates and included in FDC NOTAMsto alert pilots that segments of either an instrumentapproach procedure or a route are not navigablebecause of either the absence or unusability of aNA V AID. The pilot can expect to be provided radarnavigational guidance while transiting segmentslabeled with this term.
(See RADAR ROUTE.)
(See RADAR SERVICE.)
RADAR ROUTE − A flight path or route over which
an aircraft is vectored. Navigational guidance andaltitude assignments are provided by ATC.
(See FLIGHT PATH.)
(See ROUTE.)
RADAR SEPARA TION−
(See RADAR SERVICE.)
RADAR SER VICE− A term which encompasses one
or more of the following services based on the use of
Pilot/Controller Glossary10/12/17
PCG R−3radar which can be provided by a controller to a pilot
of a radar identified aircraft.
a.Radar Monitoring − The radar flight-following
of aircraft, whose primary navigation is beingperformed by the pilot, to observe and note deviations
from its authorized flight path, airway, or route.When being applied specifically to radar monitoringof instrument approaches; i.e., with precisionapproach radar (PAR) or radar monitoring ofsimultaneous ILS,RNA V and GLS approaches, itincludes advice and instructions whenever an aircraft
nears or exceeds the prescribed PAR safety limit orsimultaneous ILS RNA V and GLS no transgressionzone.
(See ADDITIONAL SERVICES.)
(See TRAFFIC ADVISORIES.)
b.Radar Navigational Guidance − Vectoring
aircraft to provide course guidance.
c.Radar Separation − Radar spacing of aircraft in
accordance with established minima.
(See ICAO term RADAR SERVICE.)
RADAR SERVICE [ICAO] − Term used to indicate
a service provided directly by means of radar.
a.Monitoring − The use of radar for the purpose of
providing aircraft with information and advicerelative to significant deviations from nominal flight
path.
b.Separation − The separation used when aircraft
position information is derived from radar sources.
RADAR SERVICE TERMINATED − Used by ATC
to inform a pilot that he/she will no longer beprovided any of the services that could be receivedwhile in radar contact. Radar service is automatically
terminated, and the pilot is not advised in thefollowing cases:
a.An aircraft cancels its IFR flight plan, except
within Class B airspace, Class C airspace, a TRSA,or where Basic Radar service is provided.
b.An aircraft conducting an instrument, visual, or
contact approach has landed or has been instructed tochange to advisory frequency.
c.An arriving VFR aircraft, receiving radar
service to a tower-controlled airport within Class Bairspace, Class C airspace, a TRSA, or wheresequencing service is provided, has landed; or to allother airports, is instructed to change to tower oradvisory frequency.
d.An aircraft completes a radar approach.RADAR SURVEILLANCE − The radar observation
of a given geographical area for the purpose ofperforming some radar function.
RADAR TRAFFIC ADVISORIES − Advisories
issued to alert pilots to known or observed radartraffic which may affect the intended route of flightof their aircraft.
(See TRAFFIC ADVISORIES.)
RADAR TRAFFIC INFORMATION SER VICE−
(See TRAFFIC ADVISORIES.)
RADAR VECTORING [ICAO] − Provision of
navigational guidance to aircraft in the form ofspecific headings, based on the use of radar.
RADIAL− A magnetic bearing extending from a
VOR/VORTAC/TACAN navigation facility.
RADIO−
a.A device used for communication.
b.Used to refer to a flight service station; e.g.,
“Seattle Radio” is used to call Seattle FSS.
RADIO ALTIMETER − Aircraft equipment which
makes use of the reflection of radio waves from theground to determine the height of the aircraft abovethe surface.
RADIO BEACON −
(See NONDIRECTIONAL BEACON.)
RADIO DETECTION AND RANGING −
(See RADAR.)
RADIO MAGNETIC INDICATOR − An aircraft
navigational instrument coupled with a gyro compass
or similar compass that indicates the direction of aselected NA V AID and indicates bearing with respect
to the heading of the aircraft.
RAIS−
(See REMOTE AIRPORT INFORMATION
SERVICE.)
RAMP−
(See APRON.)
RANDOM ALTITUDE − An altitude inappropriate
for direction of flight and/or not in accordance withFAA Order JO 7110.65, Para 4 −5−1, VERTICAL
SEPARATION MINIMA.
RANDOM ROUTE − Any route not established or
charted/published or not otherwise available to allusers.
RC−
(See ROAD RECONNAISSANCE.)
Pilot/Controller Glossary 10/12/17
PCG R−4RCAG−
(See REMOTE COMMUNICATIONS
AIR/GROUND FACILITY.)
RCC−
(See RESCUE COORDINATION CENTER.)
RCO−
(See REMOTE COMMUNICATIONS OUTLET.)
RCR−
(See RUNWAY CONDITION READING.)
READ BACK − Repeat my message back to me.
RECEIVER AUTONOMOUS INTEGRITY MON-
ITORING (RAIM) − A technique whereby a civil
GNSS receiver/processor determines the integrity ofthe GNSS navigation signals without reference tosensors or non-DoD integrity systems other than thereceiver itself. This determination is achieved by aconsistency check among redundant pseudorangemeasurements.
RECEIVING CONTROLLER − A controller/facility
receiving control of an aircraft from anothercontroller/facility.
RECEIVING FACILITY −
(See RECEIVING CONTROLLER.)
RECONFORMANCE − The automated process of
bringing an aircraft’s Current Plan Trajectory intoconformance with its track.
REDUCE SPEED TO (SPEED) −
(See SPEED ADJUSTMENT.)
REIL−
(See RUNWAY END IDENTIFIER LIGHTS.)
RELEASE TIME − A departure time restriction
issued to a pilot by ATC (either directly or through an
authorized relay) when necessary to separate adeparting aircraft from other traffic.
(See ICAO term RELEASE TIME.)
RELEASE TIME [ICAO] − Time prior to which an
aircraft should be given further clearance or prior towhich it should not proceed in case of radio failure.
REMOTE AIRPORT INFORMATION SERVICE
(RAIS)− A temporary service provided by facilities,
which are not located on the landing airport, but have
communication capability and automated weatherreporting available to the pilot at the landing airport.REMOTE COMMUNICATIONS AIR/GROUND
FACILITY − An unmanned VHF/UHF transmitter/
receiver facility which is used to expand ARTCCair/ground communications coverage and to facilitate
direct contact between pilots and controllers. RCAGfacilities are sometimes not equipped with emergen-cy frequencies 121.5 MHz and 243.0 MHz.
(Refer to AIM.)
REMOTE COMMUNICATIONS OUTLET − An
unmanned communications facility remotely con-trolled by air traffic personnel. RCOs serve FSSs.RTRs serve terminal ATC facilities. An RCO or RTRmay be UHF or VHF and will extend thecommunication range of the air traf fic facility. There
are several classes of RCOs and RTRs. The class isdetermined by the number of transmitters orreceivers. Classes A through G are used primarily for
air/ground purposes. RCO and RTR class Ofacilities are nonprotected outlets subject toundetected and prolonged outages. RCO (O’s) andRTR (O’s) were established for the express purposeof providing ground-to-ground communicationsbetween air traffic control specialists and pilotslocated at a satellite airport for delivering en routeclearances, issuing departure authorizations, andacknowledging instrument flight rules cancellationsor departure/landing times. As a secondary function,they may be used for advisory purposes whenever the
aircraft is below the coverage of the primaryair/ground frequency.
REMOTE TRANSMITTER/RECEIVER −
(See REMOTE COMMUNICATIONS OUTLET.)
REPORT − Used to instruct pilots to advise ATC of
specified information; e.g., “Report passing Hamil-ton VOR.”
REPORTING POINT − A geographical location in
relation to which the position of an aircraft isreported.
(See COMPULSORY REPORTING POINTS.)
(See ICAO term REPORTING POINT.)(Refer to AIM.)
REPORTING POINT [ICAO] − A specified geo-
graphical location in relation to which the position of
an aircraft can be reported.
REQUEST FULL ROUTE CLEARANCE − Used
by pilots to request that the entire route of flight beread verbatim in an ATC clearance. Such requestshould be made to precl ude recei ving an ATC
clearance based on the original filed flight plan when
Pilot/Controller Glossary10/12/17
PCG R−5a filed IFR flight plan has been revised by the pilot,
company, or operations prior to departure.
REQUIRED NA VIGATION PERFORMANCE
(RNP)– A statement of the navigational performance
necessary for operation within a defined airspace.The following terms are commonly associated withRNP:
a.Required Navigation Performance Level or
Type (RNP-X). A value, in nautical miles (NM), from
the intended horizontal position within which an
aircraft would be at least 95-percent of the total flying
time.
b.Required Navigation Performance (RNP)
Airspace. A generic term designating airspace, route
(s), leg (s), operation (s), or procedure (s) whereminimum required navigational performance (RNP)have been established.
c.Actual Navigation Performance (ANP). A
measure of the current estimated navigationalperformance. Also referred to as Estimated PositionError (EPE).
d.Estimated Position Error (EPE). A measure of
the current estimated navigational performance. Alsoreferred to as Actual Navigation Performance (ANP).
e.Lateral Navigation (LNA V). A function of area
navigation (RNA V) equipment which calculates,displays, and provides lateral guidance to a profile or
path.
f.Vertical Navigation (VNA V). A function of area
navigation (RNA V) equipment which calculates,displays, and provides vertical guidance to a profileor path.
RESCUE COORDINATION CENTER − A search
and rescue (SAR) facility equipped and manned tocoordinate and control SAR operations in an areadesignated by the SAR plan. The U.S. Coast Guardand the U.S. Air Force have responsibility for theoperation of RCCs.
(See ICAO term RESCUE CO-ORDINATION
CENTRE.)
RESCUE CO-ORDINA TION CENTRE [ICAO] − A
unit responsible for promoting efficient organization
of search and rescue service and for coordinating theconduct of search and rescue operations within asearch and rescue region.
RESOLUTION ADVISORY −A display indication
given to the pilot by the traffic alert and collisionavoidance systems (TCAS II) recommending a
maneuver to increase vertical separation relative to an
intruding aircraft. Positive, negative, and verticalspeed limit (VSL) advisories constitute the resolution
advisories. A resolution advisory is also classified as
corrective or preventive
RESTRICTED AREA −
(See SPECIAL USE AIRSPACE.)
(See ICAO term RESTRICTED AREA.)
RESTRICTED AREA [ICAO] − An airspace of
defined dimensions, above the land areas or territorial
waters of a State, within which the flight of aircraftis restricted in accordance with certain specifiedconditions.
RESUME NORMAL SPEED − Used by ATC to
advise a pilot to resume an aircraft’s normal operating
speed. It is issued to terminate a speed adjustmentwhere no published speed restrictions apply. It doesnot delete speed restrictions in published proceduresof upcoming segments of flight. This does not relievethe pilot of those speed restrictions, which areapplicable to 14 CFR Section 91.117.
RESUME OWN NAVIGATION − Used by ATC to
advise a pilot to resume his/her own navigationalresponsibility. It is issued after completion of a radar
vector or when radar contact is lost while the aircraftis being radar vectored.
(See RADAR CONTACT LOST.)
(See RADAR SERVICE TERMINATED.)
RESUME PUBLISHED SPEED- Used by ATC to
advise a pilot to resume published speed restrictionsthat are applicable to a SID, STAR, or otherinstrument procedure. It is issued to terminate a speed
adjustment where speed restrictions are published on
a charted procedure.
RMI−
(See RADIO MAGNETIC INDICATOR.)
RNA V−
(See AREA NAVIGATION (RNAV).)
RNA V APPROACH − An instrument approach
procedure which relies on aircraft area navigationequipment for navigational guidance.
(See AREA NAVIGATION (RNAV).)
(See INSTRUMENT APPROACH
PROCEDURE.)
ROAD RECONNAISSANCE − Military activity
requiring navigation along roads, railroads, and
Pilot/Controller Glossary 10/12/17
PCG R−6rivers. Reconnaissance route/route segments are
seldom along a straight line and normally require alateral route width of 10 NM to 30 NM and an altitude
range of 500 feet to 10,000 feet AGL.
ROGER − I have received all of your last
transmission. It should not be used to answer aquestion requiring a yes or a no answer.
(See AFFIRMATIVE.)
(See NEGATIVE.)
ROLLOUT RVR −
(See VISIBILITY.)
ROUTE− A defined path, consisting of one or more
courses in a horizontal plane, which aircraft traverseover the surface of the earth.
(See AIRWAY.)
(See JET ROUTE.)(See PUBLISHED ROUTE.)(See UNPUBLISHED ROUTE.)
ROUTE ACTION NOTIFICATION − EDST notifi-
cation that a P AR/PDR/PDAR has been applied to the
flight plan.
(See ATC PREFERRED ROUTE
NOTIFICATION.)
(See EN ROUTE DECISION SUPPORT TOOL)
ROUTE SEGMENT − As used in Air Traf fic Control,
a part of a route that can be defined by twonavigational fixes, two NA V AIDs, or a fix and aNA V AID.
(See FIX.)
(See ROUTE.)(See ICAO term ROUTE SEGMENT.)
ROUTE SEGMENT [ICAO] − A portion of a route to
be flown, as defined by two consecutive significantpoints specified in a flight plan.
RSA−
(See RUNWAY SAFETY AREA.)
RTR−
(See REMOTE TRANSMITTER/RECEIVER.)
RUNWAY − A defined rectangular area on a land
airport prepared for the landing and takeoff run ofaircraft along its length. Runways are normallynumbered in relation to their magnetic directionrounded off to the nearest 10 degrees; e.g., Runway1, Runway 25.
(See PARALLEL RUNWAYS.)
(See ICAO term RUNWAY.)RUNWAY [ICAO] − A defined rectangular area on a
land aerodrome prepared for the landing and take-off
of aircraft.
RUNWAY CENTERLINE LIGHTING −
(See AIRPORT LIGHTING.)
RUNWAY CONDITION CODES (RwyCC) /C0042
Numerical readings, provided by airport operators,
that indicate runway surface contamination (for
example, slush, ice, rain, etc.). These values range
from “1” ( poor) to “6” (dry) and must be included on
the ATIS when the reportable condition is less than 6
in any one or more of the three runway zones
(touchdown, midpoint, rollout).
RUNWAY CONDITION READING − Numerical
decelerometer readings relayed by air trafficcontrollers at USAF and certain civil bases for use by
the pilot in determining runway braking action.These readings are routinely relayed only to USAFand Air National Guard Aircraft.
(See BRAKING ACTION.)
RUNWAY CONDITION REPORT (RwyCR) − A
data collection worksheet used by airport operators
that correlates the runway percentage of coverage
along with the depth and type of contaminant for the
purpose of creating a FICON NOTAM.
(See RUNWAY CONDITION CODES)
RUNWAY END IDENTIFIER LIGHTS −
(See AIRPORT LIGHTING.)
RUNWAY E NTRANCE LIGHTS (REL)—An array
of red lights which include the first light at the holdline followed by a series of evenly spaced lights to the
runway edge aligned with the taxiway centerline, andone additional light at the runway centerline in linewith the last two lights before the runway edge.
RUNWAY GRADIENT − The average slope, mea-
sured in percent, between two ends or points on arunway. Runway gradient is depicted on Government
aerodrome sketches when total runway gradientexceeds 0.3%.
RUNWAY HEADING − The magnetic direction that
corresponds with the runway centerline extended, not
the painted runway number. When cleared to “fly ormaintain runway heading,” pilots are expected to fly
or maintain the heading that corresponds with theextended centerline of the departure runway. Driftcorrection shall not be applied; e.g., Runway 4, actual
magnetic heading of the runway centerline 044, fly044.
Pilot/Controller Glossary10/12/17
PCG R−7RUNWAY IN USE/ACTIVE RUNWAY/DUTY
RUNWAY − Any runway or runways currently being
used for takeoff or landing. When multiple runwaysare used, they are all considered active runways. Inthe metering sense, a selectable adapted item whichspecifies the landing runway configuration ordirection of traffic flow. The adapted optimum flight
plan from each transition fix to the vertex isdetermined by the runway configuration for arrivalmetering processing purposes.
RUNWAY LIGHTS −
(See AIRPORT LIGHTING.)
RUNWAY MARKINGS −
(See AIRPORT MARKING AIDS.)
RUNWAY OVERRUN − In military aviation exclu-
sively, a stabilized or paved area beyond the end of a
runway, of the same width as the runway plusshoulders, centered on the extended runwaycenterline.
RUNWAY PROFILE DESCENT − An instrument
flight rules (IFR) air traffic control arrival procedure
to a runway published for pilot use in graphic and/or
textual form and may be associated with a STAR.Runway Profile Descents provide routing and maydepict crossing altitudes, speed restrictions, andheadings to be flown from the en route structure to the
point where the pilot will receive clearance for andexecute an instrument approach procedure. ARunway Profile Descent may apply to more than one
runway if so stated on the chart.
(Refer to AIM.)
RUNWAY SAFETY AREA − A defined surface
surrounding the runway prepared, or suitable, forreducing the risk of damage to airplanes in the eventof an undershoot, overshoot, or excursion from therunway. The dimensions of the RSA vary and can be
determined by using the criteria contained withinAC 150/5300-13, Airport Design, Chapter 3.Figure 3−1 in AC 150/5300-13 depicts the RSA. The
design standards dictate that the RSA shall be:
a.Cleared, graded, and have no potentially
hazardous ruts, humps, depressions, or other surface
variations;
b.Drained by grading or storm sewers to prevent
water accumulation;
c.Capable, under dry conditions, of supporting
snow removal equipment, aircraft rescue andfirefighting equipment, and the occasional passage ofaircraft without causing structural damage to the
aircraft; and,
d.Free of objects, except for objects that need to
be located in the runway safety area because of theirfunction. These objects shall be constructed on lowimpact resistant supports (frangible mounted struc-tures) to the lowest practical height with the frangible
point no higher than 3 inches above grade.
(Refer to AC 150/5300-13, Airport Design,
Chapter 3.)
RUNWAY STATUS LIGHTS (RWSL)
SYSTEM—The RWSL is a system of runway andtaxiway lighting to provide pilots increasedsituational awareness by illuminating runway entrylights (REL) when the runway is unsafe for entry orcrossing, and take-off hold lights (THL) when therunway is unsafe for departure.
RUNWAY TRANSITION −
a.Conventional STARs/SIDs. The portion of a
STAR/SID that serves a particular runway orrunways at an airport.
b.RNA V STARs/SIDs. Defines a path(s) from
the common route to the final point(s) on a STAR. Fora SID, the common route that serves a particularrunway or runways at an airport.
RUNWAY USE PROGRAM − A noise abatement
runway selection plan designed to enhance noiseabatement ef forts with regard to airport communities
for arriving and departing aircraft. These plans aredeveloped into runway use programs and apply to all
turbojet aircraft 12,500 pounds or heavier; turbojetaircraft less than 12,500 pounds are included only ifthe airport proprietor determines that the aircraftcreates a noise problem. Runway use programs arecoordinated with FAA offices, and safety criteriaused in these programs are developed by the Of fice of
Flight Operations. Runway use programs areadministered by the Air Traffic Service as “Formal”or “Informal” programs.
a.Formal Runway Use Program − An approved
noise abatement program which is defined andacknowledged in a Letter of Understanding between
Flight Operations, Air Traffic Service, the airportproprietor, and the users. Once established, participa-
tion in the program is mandatory for aircraft operatorsand pilots as provided for in 14 CFR Section 91.129.
b.Informal Runway Use Program − An approved
noise abatement program which does not require a
Pilot/Controller Glossary 10/12/17
PCG R−8Letter of Understanding, and participation in the
program is voluntary for aircraft operators/pilots.
RUNWAY VISIBILITY V ALUE−
(See VISIBILITY.)
RUNWAY VISUAL RANGE −
(See VISIBILITY.)RwyCC−
(See RUNWAY CONDITION CODES.)
RwyCR−
(See RUNWAY CONDITION REPORT.)
Pilot/Controller Glossary10/12/17
PCG S−1S
SAA−
(See SPECIAL ACTIVITY AIRSPACE.)
SAFETY ALERT − A safety alert issued by ATC to
aircraft under their control if ATC is aware the aircraft
is at an altitude which, in the controller’s judgment,places the aircraft in unsafe proximity to terrain,obstructions, or other aircraft. The controller maydiscontinue the issuance of further alerts if the pilotadvises he/she is taking action to correct the situation
or has the other aircraft in sight.
a.Terrain/Obstruction Alert− A safety alert issued
by ATC to aircraft under their control if ATC is aware
the aircraft is at an altitude which, in the controller’sjudgment, places the aircraft in unsafe proximity toterrain/obstructions; e.g., “Low Altitude Alert, check
your altitude immediately.”
b.Aircraft Conflict Alert − A safety alert issued by
ATC to aircraft under their control if ATC is aware ofan aircraft that is not under their control at an altitudewhich, in the controlle r’s judgment, places both
aircraft in unsafe proximity to each other. With thealert, ATC will offer the pilot an alternate course ofaction when feasible; e.g., “Traffic Alert, advise youturn right heading zero niner zero or climb to eightthousand immediately.”
Note: The issuance of a safety alert is contingent
upon the capability of the controller to have anawareness of an unsafe condition. The course ofaction provided will be predicated on other trafficunder ATC control. Once the alert is issued, it issolely the pilot’s prerogative to determine what
course of action, if any, he/she will take.
SAFETY LOGIC SYSTEM − A software enhance-
ment to ASDE−3, ASDE−X, and ASSC, that predicts
the path of aircraft landing and/or departing, and/orvehicular movements on runways. Visual and auralalarms are activated when the safety logic projects apotential collision. The Airport Movement AreaSafety System (AMASS) is a safety logic systemenhancement to the ASDE −3. The Safety Logic
System for ASDE −X and ASSC is an integral part of
the software program.
SAFETY LOGIC SYSTEM ALERTS −
a.ALERT− An actual situation involving two real
safety logic tracks (aircraft/aircraft, aircraft/vehicle,or aircraft/other tangible object) that safety logic has
predicted will result in an imminent collision, basedupon the current set of Safety Logic parameters.
b.FALSE ALERT −
1.Alerts generated by one or more false
surface−radar tar gets that the system has interpreted
as real tracks and placed into safety logic.
2.Alerts in which the safety logic software did
not perform correctly, based upon the designspecifications and the current set of Safety Logicparameters.
3.The alert is generated by surface radar tar gets
caused by moderate or greater precipitation.
c.NUISANCE ALERT − An alert in which one or
more of the following is true:
1.The alert is generated by a known situation
that is not considered an unsafe operation, such asLAHSO or other approved operations.
2.The alert is generated by inaccurate secon-
dary radar data received by the Safety Logic System.
3.One or more of the aircraft involved in the
alert is not intending to use a runway (for example,helicopter, pipeline patrol, non −Mode C overflight,
etc.).
d.V ALID NON −ALERT− A situation in which
the safety logic software correctly determines that analert is not required, based upon the designspecifications and the current set of Safety Logicparameters.
e.INV ALID NON −ALERT− A situation in which
the safety logic software did not issue an alert whenan alert was required, based upon the designspecifications.
SAIL BACK − A maneuver during high wind
conditions (usually with power off) where float plane
movement is controlled by water rudders/openingand closing cabin doors.
SAME DIRECTION AIRCRAFT − Aircraft are
operating in the same direction when:
a.They are following the same track in the same
direction; or
b.Their tracks are parallel and the aircraft are
flying in the same direction; or
c.Their tracks intersect at an angle of less than 45
degrees.
Pilot/Controller Glossary 10/12/17
PCG S−2SAR−
(See SEARCH AND RESCUE.)
SAY AGAIN − Used to request a repeat of the last
transmission. Usually specifies transmission orportion thereof not understood or received; e.g., “Say
again all after ABRAM VOR.”
SAY ALTITUDE − Used by ATC to ascertain an
aircraft’s specific altitude/flight level. When theaircraft is climbing or descending, the pilot shouldstate the indicated altitude rounded to the nearest 100
feet.
SAY HEADING − Used by ATC to request an aircraft
heading. The pilot should state the actual heading ofthe aircraft.
SCHEDULED TIME OF ARRIV AL (STA) − A STA
is the desired time that an aircraft should cross acertain point (landing or metering fix). It takes othertraffic and airspace configuration into account. ASTA time shows the results of the TBFM schedulerthat has calculated an arrival time according toparameters such as optimized spacing, aircraftperformance, and weather.
SDF−
(See SIMPLIFIED DIRECTIONAL FACILITY.)
SEA LANE − A designated portion of water outlined
by visual surface markers for and intended to be usedby aircraft designed to operate on water.
SEARCH AND RESCUE − A service which seeks
missing aircraft and assists those found to be in need
of assistance. It is a cooperative effort using thefacilities and services of available Federal, state andlocal agencies. The U.S. Coast Guard is responsiblefor coordination of sea rch and rescue for the Maritime
Region, and the U.S. Air Force is responsible forsearch and rescue for the Inland Region. Information
pertinent to search and rescue should be passedthrough any air traffic facility or be transmitteddirectly to the Rescue Coordination Center bytelephone.
(See FLIGHT SERVICE STATION.)
(See RESCUE COORDINATION CENTER.)(Refer to AIM.)
SEARCH AND RESCUE FACILITY − A facility
responsible for maintaining and operating a searchand rescue (SAR) service to render aid to persons andproperty in distress. It is any SAR unit, station, NET,
or other operational activity which can be usefullyemployed during an SAR Mission; e.g., a Civil Air
Patrol Wing, or a Coast Guard Station.
(See SEARCH AND RESCUE.)
SECNOT −
(See SECURITY NOTICE.)
SECONDARY RADAR TARGET − A target derived
from a transponder return presented on a radardisplay.
SECTIONAL AERONAUTICAL CHARTS −
(See AERONAUTICAL CHART.)
SECTOR LIST DROP INTERV AL − A parameter
number of minutes after the meter fix time whenarrival aircraft will be deleted from the arrival sector
list.
SECURITY NOTICE (SECNOT) − A SECNOT is a
request originated by the Air Traffic SecurityCoordinator (ATSC) for an extensive communica-tions search for aircraft involved, or suspected ofbeing involved, in a security violation, or areconsidered a security risk. A SECNOT will includethe aircraft identification, search area, and expirationtime. The search area, as defined by the ATSC, could
be a single airport, multiple airports, a radius of anairport or fix, or a route of flight. Once the expiration
time has been reached, the SECNOT is considered tobe cancelled.
SECURITY SERVICES AIRSPACE − Areas
established through the regulatory process or byNOTAM, issued by the Administrator under title 14,CFR, sections 99.7, 91.141, and 91.139, whichspecify that ATC security services are required; i.e.,ADIZ or temporary flight rules areas.
SEE AND A VOID − When weather conditions
permit, pilots operating IFR or VFR are required toobserve and maneuver to avoid other aircraft.Right-of-way rules are contained in 14 CFR Part 91.
SEGMENTED CIRCLE − A system of visual
indicators designed to provide traffic patterninformation at airports without operating controltowers.
(Refer to AIM.)
SEGMENTS OF AN INSTRUMENT APPROACHPROCEDURE − An instrument approach procedure
may have as many as four separate segmentsdepending on how the approach procedure isstructured.
a.Initial Approach − The segment between the
initial approach fix and the intermediate fix or the
Pilot/Controller Glossary10/12/17
PCG S−3point where the aircraft is established on the
intermediate course or final approach course.
(See ICAO term INITIAL APPROACH
SEGMENT.)
b.Intermediate Approach − The segment between
the intermediate fix or point and the final approachfix.
(See ICAO term INTERMEDIATE APPROACH
SEGMENT.)
c.Final Approach − The segment between the final
approach fix or point and the runway, airport, ormissed approach point.
(See ICAO term FINAL APPROACH SEGMENT.)
d.Missed Approach − The segment between the
missed approach point or the point of arrival atdecision height and the missed approach fix at theprescribed altitude.
(Refer to 14 CFR Part 97.)
(See ICAO term MISSED APPROACH
PROCEDURE.)
SEPARATION − In air traffic control, the spacing of
aircraft to achieve their safe and orderly movement in
flight and while landing and taking off.
(See SEPARATION MINIMA.)
(See ICAO term SEPARATION.)
SEPARATION [ICAO] − Spacing between aircraft,
levels or tracks.
SEPARATION MINIMA − The minimum longitudi-
nal, lateral, or vertical distances by which aircraft are
spaced through the application of air traffic controlprocedures.
(See SEPARATION.)
SERVICE − A generic term that designates functions
or assistance available from or rendered by air traffic
control. For example, Class C service would denotethe ATC services provided within a Class C airspacearea.
SEVERE WEATHER A VOIDANCE PLAN − An
approved plan to minimize the affect of severeweather on traffic flows in impacted terminal and/orARTCC areas. SWAP is normally implemented toprovide the least disruption to the ATC system when
flight through portions of airspace is difficult orimpossible due to severe weather.SEVERE WEATHER FORECAST ALERTS −
Preliminary messages issued in order to alert usersthat a Severe Weather Watch Bulletin (WW) is being
issued. These messages define areas of possiblesevere thunderstorms or tornado activity. Themessages are unscheduled and issued as required bythe Storm Prediction Center (SPC) at Norman,Oklahoma.
(See AIRMET.)
(See CONVECTIVE SIGMET.)
(See CWA.)
(See SIGMET.)
SFA−
(See SINGLE FREQUENCY APPROACH.)
SFO−
(See SIMULATED FLAMEOUT.)
SHF−
(See SUPER HIGH FREQUENCY.)
SHORT RANGE CLEARANCE − A clearance
issued to a departing IFR flight which authorizes IFR
flight to a specific fix short of the destination whileair traffic control facilities are coordinating andobtaining the complete clearance.
SHORT TAKEOFF AND LANDING AIRCRAFT −
An aircraft which, at some weight within its approvedoperating weight, is capable of operating from arunway in compliance with the applicable STOLcharacteristics, airworthiness, operations, noise, andpollution standards.
(See VERTICAL TAKEOFF AND LANDING
AIRCRAFT.)
SIAP−
(See STANDARD INSTRUMENT APPROACH
PROCEDURE.)
SID−
(See STANDARD INSTRUMENT DEPARTURE.)
SIDESTEP MANEUVER − A visual maneuver
accomplished by a pilot at the completion of aninstrument approach to permit a straight-in landingon a parallel runway not more than 1,200 feet to eitherside of the runway to which the instrument approachwas conducted.
(Refer to AIM.)
SIGMET − A weather advisory issued concerning
weather significant to the safety of all aircraft.
Pilot/Controller Glossary 10/12/17
PCG S−4SIGMET advisories cover severe and extreme
turbulence, severe icing, and widespread dust orsandstorms that reduce visibility to less than 3 miles.
(See AIRMET.)
(See AWW.)
(See CONVECTIVE SIGMET.)
(See CWA.)
(See ICAO term SIGMET INFORMATION.)
(Refer to AIM.)
SIGMET INFORMATION [ICAO] − Information
issued by a meteorological watch office concerningthe occurrence or expected occurrence of specifieden-route weather phenomena which may affect thesafety of aircraft operations.
SIGNIFICANT METEOROLOGICAL INFOR-
MATION −
(See SIGMET.)
SIGNIFICANT POINT − A point, whether a named
intersection, a NAVAID, a fix derived from aNA V AID(s), or geographical coordinate expressed in
degrees of latitude and longitude, which isestablished for the purpose of providing separation,as a reporting point, or to delineate a route of flight.
SIMPLIFIED DIRECTIONAL FACILITY − A
NA V AID used for nonprecision instrumentapproaches. The final approach course is similar tothat of an ILS localizer except that the SDF coursemay be offset from the runway, generally not morethan 3 degrees, and the course may be wider than the
localizer, resulting in a lower degree of accuracy.
(Refer to AIM.)
SIMULATED FLAMEOUT − A practice approach
by a jet aircraft (normally military) at idle thrust to arunway. The approach may start at a runway (highkey) and may continue on a relatively high and widedownwind leg with a continuous turn to final. Itterminates in landing or low approach. The purposeof this approach is to simulate a flameout.
(See FLAMEOUT.)
SIMULTANEOUS CLOSE PARALLELAPPROACHES- A simultaneous, independentapproach operation permitting ILS/RNA V/GLSapproaches to airports having parallel runwaysseparated by at least 3,000 feet and less than 4300 feet
between centerlines. Aircraft are permitted to passeach other during these simultaneous operations.Integral parts of a total system are radar, NTZmonitoring with enhanced FMA color displays thatinclude aural and visual alerts and predictive aircraft
position software, communications override, ATCprocedures, an Attention All Users Page (AAUP),PRM in the approach name, and appropriate groundbased and airborne equipment. High update ratesurveillance sensor required for certain runway orapproach course separations.
SIMULTANEOUS (CONVERGING)
DEPENDENT APPROACHES-An approachoperation permitting ILS/RNA V/GLS approaches torunways or missed approach courses that intersectwhere required minimum spacing between theaircraft on each final approach course is required.
SIMULTANEOUS (CONVERGING)
INDEPENDENT APPROACHES- An approachoperation permitting ILS/RNA V/GLS approaches tonon-parallel runways where approach proceduredesign maintains the required aircraft spacingthroughout the approach and missed approach andhence the operations may be conductedindependently.
SIMULTANEOUS ILS APPROACHES − An
approach system permitting simultaneous ILSapproaches to airports having parallel runwaysseparated by at least 4,300 feet between centerlines.Integral parts of a total system are ILS, radar,communications, ATC procedures, and appropriateairborne equipment.
(See PARALLEL RUNWAYS.)
(Refer to AIM.)
SIMULTANEOUS OFFSET INSTRUMENT
APPROACH (SOIA) − An instrument landing
system comprised of an ILS PRM, RNA V PRM orGLS PRM approach to one runway and an offsetLDA PRM with glideslope or an RNA V PRM orGLS PRM approach utilizing vertical guidance toanother where parallel runway spaced less than 3,000
feet and at least 750 feet apart. The approach courses
converge by 2.5 to 3 degrees. Simultaneous closeparallel PRM approach procedures apply up to thepoint where the approach course separation becomes
3,000 feet, at the offset MAP. From the offset MAPto the runway threshold, visual separation by theaircraft conducting the offset approach is utilized.
(Refer to AIM)
SIMULTANEOUS (PARALLEL) DEPENDENTAPPROACHES- An approach operation permittingILS/RNA V/GLS approaches to adjacent parallelrunways where prescribed diagonal spacing must be
Pilot/Controller Glossary10/12/17
PCG S−5maintained. Aircraft are not permitted to pass each
other during simultaneous dependent operations.Integral parts of a total system ATC procedures, andappropriate airborne and ground based equipment.
SINGLE DIRECTION ROUTES − Preferred IFR
Routes which are sometimes depicted on highaltitude en route charts and which are normally flown
in one direction only.
(See PREFERRED IFR ROUTES.)
(Refer to CHART SUPPLEMENT U.S.)
SINGLE FREQUENCY APPROACH − A service
provided under a letter of agreement to militarysingle-piloted turbojet aircraft which permits use ofa single UHF frequency during approach for landing.Pilots will not normally be required to changefrequency from the beginning of the approach totouchdown except that pilots conducting an en route
descent are required to change frequency whencontrol is transferred from the air route traf fic control
center to the terminal facility. The abbreviation“SFA” in the DOD FLIP IFR Supplement under“Communications” indicates this service is available
at an aerodrome.
SINGLE-PILOTED AIRCRAFT − A military
turbojet aircraft possessing one set of flight controls,
tandem cockpits, or two sets of flight controls butoperated by one pilot is considered single-piloted byATC when determining the appropriate air trafficservice to be applied.
(See SINGLE FREQUENCY APPROACH.)
SKYSPOTTER − A pilot who has received
specialized training in observing and reportinginflight weather phenomena.
SLASH− A radar beacon reply displayed as an
elongated target.
SLDI−
(See SECTOR LIST DROP INTERVAL.)
SLOT TIME −
(See METER FIX TIME/SLOT TIME.)
SLOW TAXI − To taxi a float plane at low power or
low RPM.
SN−
(See SYSTEM STRATEGIC NAVIGATION.)
SPEAK SLOWER − Used in verbal communications
as a request to reduce speech rate.SPECIAL ACTIVITY AIRSPACE (SAA) − Any
airspace with defined dimensions within the National
Airspace System wherein limitations may beimposed upon aircraft operations. This airspace maybe restricted areas, prohibited areas, militaryoperations areas, air ATC assigned airspace, and any
other designated airspace areas. The dimensions ofthis airspace are programmed into EDST and can bedesignated as either active or inactive by screen entry.
Aircraft trajectories are constantly tested against thedimensions of active areas and alerts issued to theapplicable sectors when violations are predicted.
(See EN ROUTE DECISION SUPPORT TOOL .)
SPECIAL AIR TRAFFIC RULES (SATR) − Rules
that govern procedures for conducting flights in
certain areas listed in 14 CFR Part 93. The term
“SATR” is used in the United States to describe the
rules for operations in specific areas designated in the
Code of Federal Regulations.
(Refer to 14 CFR Part 93)
SPECIAL EMERGENCY − A condition of air piracy
or other hostile act by a person(s) aboard an aircraftwhich threatens the safety of the aircraft or itspassengers.
SPECIAL INSTRUMENT APPROACH PROCE-
DURE−
(See INSTRUMENT APPROACH PROCEDURE.)
SPECIAL USE AIRSPACE − Airspace of defined
dimensions identified by an area on the surface of the
earth wherein activities must be confined because oftheir nature and/or wherein limitations may beimposed upon aircraft operations that are not a part of
those activities. Types of special use airspace are:
a.Alert Area− Airspace which may contain a high
volume of pilot training activities or an unusual typeof aerial activity, neither of which is hazardous toaircraft. Alert Areas are depicted on aeronauticalcharts for the information of nonparticipating pilots.All activities within an Alert Area are conducted inaccordance with Federal Aviation Regulations, andpilots of participating aircraft as well as pilotstransiting the area are equally responsible forcollision avoidance.
b.Controlled Firing Area − Airspace wherein
activities are conducted under conditions socontrolled as to eliminate hazards to nonparticipating
aircraft and to ensure the safety of persons andproperty on the ground.
Pilot/Controller Glossary 10/12/17
PCG S−6c.Military Operations Area (MOA) − A MOA is
airspace established outside of Class A airspace area
to separate or segr egate certain nonhazardous
military activities from IFR traffic and to identify for
VFR traffic where these activities are conducted.
(Refer to AIM.)
d.Prohibited Area − Airspace designated under
14 CFR Part 73 within which no person may operate
an aircraft without the permission of the usingagency.
(Refer to AIM.)
(Refer to En Route Charts.)
e.Restricted Area − Airspace designated under
14 CFR Part 73, within which the flight of aircraft,while not wholly prohibited, is subject to restriction.Most restricted areas are designated joint use andIFR/VFR operations in the area may be authorized by
the controlling ATC facility when it is not beingutilized by the using agency. Restricted areas aredepicted on en route charts. Where joint use isauthorized, the name of the ATC controlling facilityis also shown.
(Refer to 14 CFR Part 73.)
(Refer to AIM.)
f.Warning Area − A warning area is airspace of
defined dimensions extending from 3 nautical milesoutward from the coast of the United States, thatcontains activity that may be hazar dous to
nonparticipating aircraft. The purpose of suchwarning area is to warn nonparticipating pilots of the
potential danger. A warning area may be located over
domestic or international waters or both.
SPECIAL VFR CONDITIONS − Meteorological
conditions that are less than those required for basicVFR flight in Class B, C, D, or E surface areas andin which some aircraft are permitted flight undervisual flight rules.
(See SPECIAL VFR OPERATIONS.)
(Refer to 14 CFR Part 91.)
SPECIAL VFR FLIGHT [ICAO] − A VFR flight
cleared by air traffic control to operate within ClassB, C, D, and E surface areas in metrologicalconditions below VMC.
SPECIAL VFR OPERATIONS − Aircraft operating
in accordance with clearances within Class B, C, D,and E surface areas in weather conditions less than thebasic VFR weather minima. Such operations must be
requested by the pilot and approved by ATC.
(See SPECIAL VFR CONDITIONS.)
(See ICAO term SPECIAL VFR FLIGHT.)
SPEED−
(See AIRSPEED.)
(See GROUND SPEED.)
SPEED ADJUSTMENT − An A TC procedure used to
request pilots to adjust aircraft speed to a specificvalue for the purpose of providing desired spacing.Pilots are expected to maintain a speed of plus orminus 10 knots or 0.02 Mach number of the specified
speed. Examples of speed adjustments are:
a.“Increase/reduce speed to Mach point
(number.)”
b.“Increase/reduce speed to (speed in knots)” or
“Increase/reduce speed (number of knots) knots.”
SPEED BRAKES − Moveable aerodynamic devices
on aircraft that reduce airspeed during descent andlanding.
SPEED SEGMENTS − Portions of the arrival route
between the transition point and the vertex along theoptimum flight path for which speeds and altitudesare specified. There is one set of arrival speedsegments adapted from each transition point to eachvertex. Each set may contain up to six segments.
SQUAWK (Mode, Code, Function) − Activate
specific modes/codes/functions on the aircrafttransponder; e.g., “Squawk three/alpha, two one zero
five, low.”
(See TRANSPONDER.)
STA−
(See SCHEDULED TIME OF ARRIVAL.)
STAGING/QUEUING − The placement, integration,
and segregation of departure aircraft in designatedmovement areas of an airport by departure fix, EDCT,
and/or restriction.
STAND BY − Means the controller or pilot must
pause for a few seconds, usually to attend to otherduties of a higher priority. Also means to wait as in“stand by for clearance.” The caller shouldreestablish contact if a delay is lengthy. “Stand by” is
not an approval or denial.
STANDARD INSTRUMENT APPROACH PRO-
CEDURE (SIAP) −
(See INSTRUMENT APPROACH PROCEDURE.)
STANDARD INSTRUMENT DEPAR TURE (SID) −
A preplanned instrument flight rule (IFR) air traffic
Pilot/Controller Glossary10/12/17
PCG S−7control (ATC) departure procedure printed for
pilot/controller use in graphic form to provideobstacle clearance and a transition from the terminalarea to the appropriate en route structure. SIDs areprimarily designed for system enhancement toexpedite traffic flow and to reduce pilot/controllerworkload. ATC clearance must always be receivedprior to flying a SID.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
(See OBSTACLE DEPARTURE PROCEDURE.)(Refer to AIM.)
STANDARD RATE TURN − A turn of three degrees
per second.
STANDARD TERMINAL ARRIV AL − A
preplanned instrument flight rule (IFR) air trafficcontrol arrival procedure published for pilot use ingraphic and/or textual form. STARs providetransition from the en route structure to an outer fixor an instrument approach fix/arrival waypoint in theterminal area.
STANDARD TERMINAL ARRIV AL CHARTS −
(See AERONAUTICAL CHART.)
STANDARD TERMINAL AUTOMATION RE-
PLACEMENT SYSTEM (STARS)−
(See DTAS.)
STAR−
(See STANDARD TERMINAL ARRIVAL.)
STATE AIRCRAFT − Aircraft used in military,
customs and police service, in the exclusive serviceof any government, or of any political subdivision,thereof including the government of any state,territory, or possession of the United States or theDistrict of Columbia, but not including anygovernment-owned aircraft engaged in carryingpersons or property for commercial purposes.
STATIC RESTRICTIONS − Those restrictions that
are usually not subject to change, fixed, in place,and/or published.
STATIONARY RESERV ATIONS − Altitude
reservations which encompass activities in a fixedarea. Stationary reservations may include activities,such as special tests of weapons systems orequipment, certain U.S. Navy carrier, fleet, andanti-submarine operations, rocket, missile and drone
operations, and certain aerial refueling or similaroperations.STEP TAXI − To taxi a float plane at full power or
high RPM.
STEP TURN − A maneuver used to put a float plane
in a planing configuration prior to entering an active
sea lane for takeoff. The STEP TURN maneuvershould only be used upon pilot request.
STEPDOWN FIX − A fix permitting additional
descent within a segment of an instrument approachprocedure by identifying a point at which acontrolling obstacle has been safely overflown.
STEREO ROUTE − A routinely used route of flight
established by users and ARTCCs identified by acoded name; e.g., ALPHA 2. These routes minimizeflight plan handling and communications.
STOL AIRCRAFT −
(See SHORT TAKEOFF AND LANDING
AIRCRAFT.)
STOP ALTITUDE SQUAWK − Used by ATC to
inform an aircraft to turn-off the automatic altitudereporting feature of its transponder. It is issued when
the verbally reported altitude varies 300 feet or morefrom the automatic altitude report.
(See ALTITUDE READOUT.)
(See TRANSPONDER.)
STOP AND GO − A procedure wherein an aircraft
will land, make a complete stop on the runway, andthen commence a takeoff from that point.
(See LOW APPROACH.)
(See OPTION APPROACH.)
STOP BURST −
(See STOP STREAM.)
STOP BUZZER −
(See STOP STREAM.)
STOP SQUAWK (Mode or Code) − Used by ATC to
tell the pilot to turn specified functions of the aircraft
transponder off.
(See STOP ALTITUDE SQUAWK.)
(See TRANSPONDER.)
STOP STREAM − Used by ATC to request a pilot to
suspend electronic attack activity.
(See JAMMING.)
STOPOVER FLIGHT PLAN − A flight plan format
which permits in a single submission the filing of asequence of flight plans through interim full-stopdestinations to a final destination.
STOPWAY − An area beyond the takeoff runway no
less wide than the runway and centered upon the
Pilot/Controller Glossary 10/12/17
PCG S−8extended centerline of the runway, able to support the
airplane during an aborted takeoff, without causingstructural damage to the airplane, and designated bythe airport authorities for use in decelerating theairplane during an aborted takeoff.
STRAIGHT-IN APPROACH IFR − An instrument
approach wherein final approach is begun withoutfirst having executed a procedure turn, notnecessarily completed with a straight-in landing ormade to straight-in landing minimums.
(See LANDING MINIMUMS.)
(See STRAIGHT-IN APPROACH VFR.)
(See STRAIGHT-IN LANDING.)
STRAIGHT-IN APPROACH VFR − Entry into the
traffic pattern by interception of the extended runway
centerline (final approach course) without executingany other portion of the traffic pattern.
(See TRAFFIC PATTERN.)
STRAIGHT-IN LANDING − A landing made on a
runway aligned within 30 /C0095 of the final approach
course following completion of an instrumentapproach.
(See STRAIGHT-IN APPROACH IFR.)
STRAIGHT-IN LANDING MINIMUMS −
(See LANDING MINIMUMS.)
STRAIGHT-IN MINIMUMS −
(See STRAIGHT-IN LANDING MINIMUMS.)
STRATEGIC PLANNING − Planning whereby
solutions are sought to resolve potential conflicts.
SUBSTITUTE ROUTE − A route assigned to pilots
when any part of an airway or route is unusablebecause of NA V AID status. These routes consist of:
a.Substitute routes which are shown on U.S.
Government charts.
b.Routes defined by ATC as specific NA V AID
radials or courses.
c.Routes defined by ATC as direct to or between
NA V AIDs.
SUNSET AND SUNRISE − The mean solar times of
sunset and sunrise as published in the NauticalAlmanac, converted to local standard time for thelocality concerned. Within Alaska, the end of eveningcivil twilight and the beginning of morning civil
twilight, as defined for each locality.
SUPPLEMENTAL WEATHER SERVICE
LOCA TION− Airport facilities staffed with contract
personnel who take weather observations andprovide current local weather to pilots via telephoneor radio. (All other services are provided by the parentFSS.)
SUPPS− Refers to ICAO Document 7030 Regional
Supplementary Procedures. SUPPS containprocedures for each ICAO Region which are uniqueto that Region and are not covered in the worldwideprovisions identified in the ICAO Air NavigationPlan. Procedures contained in Chapter 8 are based in
part on those published in SUPPS.
SURFACE AREA − The airspace contained by the
lateral boundary of the Class B, C, D, or E airspacedesignated for an airport that begins at the surface and
extends upward.
SURPIC− A description of surface vessels in the area
of a Search and Rescue incident including theirpredicted positions and their characteristics.
(Refer to FAA Order JO 7110.65, Para 10 −6−4,
INFLIGHT CONTINGENCIES.)
SURVEILLANCE APPROACH − An instrument
approach wherein the air traffic controller issuesinstructions, for pilot compliance, based on aircraftposition in relation to the final approach course(azimuth), and the distance (range) from the end ofthe runway as displayed on the controller’s radarscope. The controller will provide recommendedaltitudes on final approach if requested by the pilot.
(Refer to AIM.)
SWAP−
(See SEVERE WEATHER AVOIDANCE PLAN.)
SWSL−
(See SUPPLEMENTAL WEATHER SERVICE
LOCATION.)
SYSTEM STRATEGIC NA VIGATION − Military
activity accomplished by navigating along apreplanned route using internal aircraft systems tomaintain a desired track. This activity normallyrequires a lateral route width of 10 NM and altituderange of 1,000 feet to 6,000 feet AGL with some route
segments that permit terrain following.
Pilot/Controller Glossary10/12/17
PCG T−1T
TACAN−
(See TACTICAL AIR NAVIGATION.)
TACAN-ONLY AIRCRAFT − An aircraft, normally
military, possessing TACAN with DME but no VOR
navigational system capability. Clearances mustspecify TACAN or VORTAC fixes and approaches.
TACTICAL AIR NA VIGATION − An ultra-high
frequency electronic rho-theta air navigation aidwhich provides suitably equipped aircraft acontinuous indication of bearing and distance to theTACAN station.
(See VORTAC.)
(Refer to AIM.)
TAILWIND − Any wind more than 90 degrees to the
longitudinal axis of the runway. The magneticdirection of the runway shall be used as the basis for
determining the longitudinal axis.
TAKEOFF AREA −
(See LANDING AREA.)
TAKEOFF DISTANCE A V AILABLE (TODA)– The
takeoff run available plus the length of any remaining
runway or clearway beyond the far end of the takeoff
run available.
(See ICAO term TAKEOFF DISTANCE
AVAILABLE.)
TAKEOFF DIST ANCE A V AILABLE [ICAO] − The
length of the takeoff run available plus the length ofthe clearway, if provided.
TAKEOFF HOLD LIGHTS (THL)– The THL
system is composed of in-pavement lighting in adouble, longitudinal row of lights aligned either side
of the runway centerline. The lights are focusedtoward the arrival end of the runway at the “line upand wait” point, and they extend for 1,500 feet infront of the holding aircraft. Illuminated red lightsindicate to an aircraft in position for takeoff or rolling
that it is unsafe to takeoff because the runway isoccupied or about to be occupied by an aircraft orvehicle.
TAKEOFF ROLL − The process whereby an aircraft
is aligned with the runway centerline and the aircraftis moving with the intent to take of f. For helicopters,this pertains to the act of becoming airborne after
departing a takeoff area.
TAKEOFF RUN A V AILABLE (TORA) – The
runway length declared available and suitable for the
ground run of an airplane taking off.
(See ICAO term TAKEOFF RUN AVAILABLE.)
TAKEOFF RUN A V AILABLE [ICAO] − The length
of runway declared available and suitable for theground run of an aeroplane take-off.
TARGET − The indication shown on an analog
display resulting from a primary radar return or aradar beacon reply.
(See ASSOCIATED.)
(See DIGITAL TARGET.)
(See DIGITIZED RADAR TARGET.)
(See FUSED TARGET)(See PRIMARY RADAR TARGET.)(See RADAR.)(See SECONDARY RADAR TARGET.)
(See TARGET SYMBOL.)
(See ICAO term TARGET.)(See UNASSOCIATED.)
TARGET [ICAO] − In radar:
a.Generally, any discrete object which reflects or
retransmits energy back to the radar equipment.
b.Specifically, an object of radar search or
surveillance.
TARGET RESOLUTION − A process to ensure that
correlated radar targets do not touch. Targetresolution must be applied as follows:
a.Between the edges of two primary targets or the
edges of the ASR-9/11 primary target symbol.
b.Between the end of the beacon control slash and
the edge of a primary target.
c.Between the ends of two beacon control slashes.
Note 1: Mandatory traffic advisories and safety
alerts must be issued when this procedure is used.
Note 2: This procedure must not be used when
utilizing mosaic radar systems or multi −sensor
mode.
TARGET SYMBOL − A computer -generated indica-
tion shown on a radar display resulting from aprimary radar return or a radar beacon reply.
Pilot/Controller Glossary 10/12/17
PCG T−2TARMAC DELAY− The holding of an aircraft on the
ground either before departure or after landing withno opportunity for its passengers to deplane.
TARMAC DELAY AIRCRAFT − An aircraft whose
pilot−in−command has requested to taxi to the ramp,
gate, or alternate deplaning area to comply with theThree−hour T armac Rule.
TARMAC DELAY REQUEST − A request by the
pilot−in−command to taxi to the ramp, gate, or
alternate deplaning location to comply with theThree−hour T armac Rule.
TAS−
(See TERMINAL AUTOMATION SYSTEMS.)
TAWS−
(See TERRAIN AWARENESS WARNING
SYSTEM.)
TAXI− The movement of an airplane under its own
power on the surface of an airport (14 CFRSection 135.100 [Note]). Also, it describes thesurface movement of helicopters equipped withwheels.
(See AIR TAXI.)
(See HOVER TAXI.)
(Refer to 14 CFR Section 135.100.)(Refer to AIM.)
TAXI PATTERNS − Patterns established to illustrate
the desired flow of ground traffic for the differentrunways or airport areas available for use.
TCAS−
(See TRAFFIC ALERT AND COLLISION
AVOIDANCE SYSTEM.)
TCH−
(See THRESHOLD CROSSING HEIGHT.)
TCLT−
(See TENTATIVE CALCULATED LANDING
TIME.)
TDLS−
(See TERMINAL DATA LINK SYSTEM .)
TDZE−
(See TOUCHDOWN ZONE ELEVATION.)
TELEPHONE INFORMATION BRIEFING SER-
VICE− A continuous telephone recording of
meteorological and/or aeronautical information.
(Refer to AIM.)TEMPORARY FLIGHT RESTRICTION (TFR) − A
TFR is a regulatory action issued by the FAA via theU.S. NOTAM System, under the authority of UnitedStates Code, Title 49. TFRs are issued within thesovereign airspace of the United States and itsterritories to restrict certain aircraft from operatingwithin a defined area on a temporary basis to protect
persons or property in the air or on the ground. While
not all inclusive, TFRs may be issued for disaster orhazard situations such as: toxic gas leaks or spills,fumes from flammable agents, aircraft accident/in-cident sites, aviation or ground resources engaged inwildfire suppression, or aircraft relief activitiesfollowing a disaster. TFRs may also be issued insupport of VIP movements; for reasons of nationalsecurity; or when determined necessary for themanagement of air traffic in the vicinity of aerialdemonstrations or major sporting events. NAS users
or other interested parties should contact a FSS forTFR information. Additionally , TFR information can
be found in automated briefings, NOTAM publica-tions, and on the internet at http://www.faa.gov. TheFAA also distributes TFR information to aviationuser groups for further dissemination.
TENTATIVE CALCULA TED LANDING TIME − A
projected time calculated for adapted vertex for each
arrival aircraft based upon runway configuration,airport acceptance rate, airport arrival delay period,and other metered arrival aircraft. This time is eitherthe VTA of the aircraft or the TCLT/ACLT of theprevious aircraft plus the AAI, whichever is later.This time will be updated in response to an aircraft’sprogress and its current relationship to other arrivals.
TERMINAL AREA− A general term used to describe
airspace in which approach control service or airport
traffic control service is provided.
TERMINAL AREA FACILITY − A facility provid-
ing air traffic control service for arriving anddeparting IFR, VFR, Special VFR, and on occasionen route aircraft.
(See APPROACH CONTROL FACILITY.)
(See TOWER.)
TERMINAL AUTOMATION SYSTEMS (TAS) −
TAS is used to identify the numerous automatedtracking systems including ARTS IIE, ARTS IIIA,ARTS IIIE, STARS, and MEARTS.
TERMINAL DATA LINK SYSTEM (TDLS) − A
system that provides Digital Automatic TerminalInformation Service (D −ATIS) both on a specified
Pilot/Controller Glossary10/12/17
PCG T−3radio frequency and also, for subscribers, in a text
message via data link to the cockpit or to a gateprinter. TDLS also provides Pre −departure Clear-
ances (PDC), at selected airports, to subscribers,through a service provider, in text to the cockpit or to
a gate printer. In addition, TDLS will emulate theFlight Data Input/Output (FDIO) information withinthe control tower.
TERMINAL RADAR SERVICE AREA − Airspace
surrounding designated airports wherein ATCprovides radar vectoring, sequencing, and separation
on a full-time basis for all IFR and participating VFR
aircraft. The AIM contains an explanation of TRSA.
TRSAs are depicted on VFR aeronautical charts.Pilot participation is urged but is not mandatory.
TERMINAL VFR RADAR SERVICE − A national
program instituted to extend the terminal radarservices provided instrument flight rules (IFR)aircraft to visual flight rules (VFR) aircraft. Theprogram is divided into four types service referred to
as basic radar service, terminal radar service area(TRSA) service, Class B service and Class C service.
The type of service provided at a particular locationis contained in the Chart Supplement U.S.
a.Basic Radar Service − These services are
provided for VFR aircraft by all commissionedterminal radar facilities. Basic radar service includes
safety alerts, traffic advisories, limited radarvectoring when requested by the pilot, andsequencing at locations where procedures have beenestablished for this purpose and/or when covered bya letter of agreement. The purpose of this service is toadjust the flow of arriving IFR and VFR aircraft into
the traffic pattern in a safe and orderly manner and to
provide traffic advisories to departing VFR aircraft.
b.TRSA Service − This service provides, in
addition to basic radar service, sequencing of all IFR
and participating VFR aircraft to the primary airportand separation between all participating VFRaircraft. The purpose of this service is to provideseparation between all participating VFR aircraft and
all IFR aircraft operating within the area defined as aTRSA.
c.Class C Service − This service provides, in
addition to basic radar service, approved separationbetween IFR and VFR aircraft, and sequencing ofVFR aircraft, and sequencing of VFR arrivals to theprimary airport.d.Class B Service − This service provides, in
addition to basic radar service, approved separationof aircraft based on IFR, VFR, and/or weight, andsequencing of VFR arrivals to the primary airport(s).
(See CONTROLLED AIRSPACE.)
(See TERMINAL RADAR SERVICE AREA.)
(Refer to AIM.)
(Refer to CHART SUPPLEMENT U.S.)
TERMINAL-VERY HIGH FREQUENCY OMNI-
DIRECTIONAL RANGE STA TION− A very high
frequency terminal omnirange station located on ornear an airport and used as an approach aid.
(See NAVIGATIONAL AID.)
(See VOR.)
TERRAIN AWARENESS WARNING SYSTEM
(TAWS)− An on−board, terrain proximity alerting
system providing the aircrew ‘Low Altitudewarnings’ to allow immediate pilot action.
TERRAIN FOLLOWING − The flight of a military
aircraft maintaining a constant AGL altitude abovethe terrain or the highest obstruction. The altitude ofthe aircraft will constantly change with the varyingterrain and/or obstruction.
TETRAHEDRON − A device normally located on
uncontrolled airports and used as a landing direction
indicator. The small end of a tetrahedron points in the
direction of landing. At controlled airports, thetetrahedron, if installed, should be disregardedbecause tower instructions supersede the indicator.
(See SEGMENTED CIRCLE.)
(Refer to AIM.)
TF−
(See TERRAIN FOLLOWING.)
THAT IS CORRECT − The understanding you have
is right.
THREE−HOUR TARMAC RULE– Rule that relates
to Department of T ransportation (DOT) requirements
placed on airlines when tarmac delays are anticipated
to reach 3 hours.
360 OVERHEAD −
(See OVERHEAD MANEUVER.)
THRESHOLD − The beginning of that portion of the
runway usable for landing.
(See AIRPORT LIGHTING.)
(See DISPLACED THRESHOLD.)
THRESHOLD CROSSING HEIGHT − The
theoretical height above the runway threshold at
Pilot/Controller Glossary 10/12/17
PCG T−4which the aircraft’s glideslope antenna would be if
the aircraft maintains the trajectory established by themean ILS glideslope or the altitude at which thecalculated glidepath of an RNA V or GPS approaches.
(See GLIDESLOPE.)
(See THRESHOLD.)
THRESHOLD LIGHTS −
(See AIRPORT LIGHTING.)
TIBS−
(See TELEPHONE INFORMATION BRIEFING
SERVICE.)
TIE-IN FACILITY– The FSS primarily responsible
for providing FSS services, including telecommu-nications services for landing facilities ornavigational aids located within the boundaries of aflight plan area (FPA). Three-letter identifiers areassigned to each FSS/FPA and are annotated as tie-in
facilities in the Chart Supplement U.S., the AlaskaSupplement, the Pacific Supplement, and FAA Order
JO 7350.9, Location Identifiers. Large consolidatedFSS facilities may have many tie-in facilities or FSSsectors within one facility.
(See FLIGHT PLAN AREA.)
(See FLIGHT SERVICE STATION.)
TIME BASED FLOW MANAGEMENT (TBFM) −
The hardware, software, methods, processes, andinitiatives to manage air traffic flows based on timeto balance air traffic demand with system capacity,and support the management of PBN. This includes,but not limited to, Adjacent Center Metering (ACM).En Route Departure Capability (EDC),Ground-Interval Management-Spacing (GIM-S),Integrated Departure/Arrival Capability (IDAC),Single Center Metering (SCM), Time-BasedMetering (TBM), Time-Based Scheduling (TBS),and Extended/Coupled Metering.
TIME GROUP − Four digits representing the hour
and minutes from the Coordinated Universal Time(UTC) clock. FAA uses UTC for all operations. Theterm “ZULU” may be used to denote UTC. The word
“local” or the time zone equivalent shall be used todenote local when local time is given during radio and
telephone communications. When written, a timezone designator is used to indicate local time; e.g.“0205M” (Mountain). The local time may be basedon the 24-hour clock system. The day begins at 0000
and ends at 2359.TIS−B−
(See TRAFFIC INFORMATION
SERVICE −BROADCAST.)
TMPA−
(See TRAFFIC MANAGEMENT PROGRAM
ALERT.)
TMU−
(See TRAFFIC MANAGEMENT UNIT.)
TODA−
(See TAKEOFF DISTANCE AVAILABLE.)
(See ICAO term TAKEOFF DISTANCE
AVAILABLE.)
TOI−
(See TRACK OF INTEREST.)
TOP ALTITUDE– In reference to SID published
altitude restrictions the charted “maintain” altitude
contained in the procedure description or assigned by
ATC.
TORA−
(See TAKEOFF RUN AVAILABLE.)
(See ICAO term TAKEOFF RUN AVAILABLE.)
TORCHING − The burning of fuel at the end of an
exhaust pipe or stack of a reciprocating aircraftengine, the result of an excessive richness in the fuel
air mixture.
TOS−
(See TRAJECTORY OPTIONS SET)
TOTAL ESTIMATED ELAPSED TIME [ICAO] −
For IFR flights, the estimated time required fromtake-off to arrive over that designated point, definedby reference to navigation aids, from which it isintended that an instrument approach procedure willbe commenced, or, if no navigation aid is associatedwith the destination aerodrome, to arrive over thedestination aerodrome. For VFR flights, theestimated time required from take-off to arrive overthe destination aerodrome.
(See ICAO term ESTIMATED ELAPSED TIME.)
TOUCH-AND-GO − An operation by an aircraft that
lands and departs on a runway without stopping orexiting the runway.
TOUCH-AND-GO LANDING −
(See TOUCH-AND-GO.)
TOUCHDOWN −
a.The point at which an aircraft first makes
contact with the landing surface.
Pilot/Controller Glossary10/12/17
PCG T−5b.Concerning a precision radar approach (PAR),
it is the point where the glide path intercepts thelanding surface.
(See ICAO term TOUCHDOWN.)
TOUCHDOWN [ICAO] − The point where the
nominal glide path intercepts the runway.
Note: Touchdown as defined above is only a datum
and is not necessarily the actual point at which theaircraft will touch the runway.
TOUCHDOWN RVR −
(See VISIBILITY.)
TOUCHDOWN ZONE − The first 3,000 feet of the
runway beginning at the threshold. The area is usedfor determination of Touchdown Zone Elevation inthe development of straight-in landing minimums forinstrument approaches.
(See ICAO term TOUCHDOWN ZONE.)
TOUCHDOWN ZONE [ICAO] − The portion of a
runway, beyond the threshold, where it is intendedlanding aircraft first contact the runway.
TOUCHDOWN ZONE ELEV ATION − The highest
elevation in the first 3,000 feet of the landing surface.
TDZE is indicated on the instrument approachprocedure chart when straight-in landing minimumsare authorized.
(See TOUCHDOWN ZONE.)
TOUCHDOWN ZONE LIGHTING −
(See AIRPORT LIGHTING.)
TOWER− A terminal facility that uses air/ground
communications, visual signaling, and other devices
to provide ATC services to aircraft operating in thevicinity of an airport or on the movement area.Authorizes aircraft to land or takeoff at the airportcontrolled by the tower or to transit the Class Dairspace area regardless of flight plan or weatherconditions (IFR or VFR). A tower may also provideapproach control services (radar or nonradar).
(See AIRPORT TRAFFIC CONTROL SERVICE.)
(See APPROACH CONTROL FACILITY.)
(See APPROACH CONTROL SERVICE.)
(See MOVEMENT AREA.)
(See TOWER EN ROUTE CONTROL
SERVICE.)
(See ICAO term AERODROME CONTROL
TOWER.)
(Refer to AIM.)TOWER EN ROUTE CONTROL SERVICE − The
control of IFR en route traffic within delegatedairspace between two or more adjacent approachcontrol facilities. This service is designed to expedite
traffic and reduce control and pilot communicationrequirements.
TOWER TO TOWER −
(See TOWER EN ROUTE CONTROL
SERVICE.)
TRACEABLE PRESSURE STANDARD − The
facility station pressure instrument, with certifica-tion/calibration traceable to the National Institute ofStandards and Technology . Traceable pressure
standards may be mercurial barometers, commis-sioned ASOS/AWSS or dual transducer AWOS, orportable pressure standards or DASI.
TRACK− The actual flight path of an aircraft over the
surface of the earth.
(See COURSE.)
(See FLIGHT PATH.)(See ROUTE.)(See ICAO term TRACK.)
TRACK [ICAO] − The projection on the earth’s
surface of the path of an aircraft, the direction ofwhich path at any point is usually expressed indegrees from North (True, Magnetic, or Grid).
TRACK OF INTEREST (TOI) − Displayed data
representing an airborne object that threatens or hasthe potential to threaten North America or NationalSecurity. Indicators may include, but are not limitedto: noncompliance with air traffic control instructions
or aviation regulations; extended loss of communica-tions; unusual transmissions or unusual flightbehavior; unauthorized intrusion into controlledairspace or an ADIZ; noncompliance with issuedflight restrictions/security procedures; or unlawfulinterference with airborne flight crews, up to andincluding hijack. In certain circumstances, an objectmay become a TOI based on specific and credibleintelligence pertaining to that particular aircraft/object, its passengers, or its cargo.
TRACK OF INTEREST RESOLUTION − A TOI
will normally be considered resolved when: theaircraft/object is no longer airborne; the aircraftcomplies with air traf fic control instructions, aviation
regulations, and/or issued flight restrictions/securityprocedures; radio contact is re −established and
authorized control of the aircraft is verified; theaircraft is intercepted and intent is verified to be
Pilot/Controller Glossary 10/12/17
PCG T−6nonthreatening/nonhostile; T OI was identified based
on specific and credible intelligence that was laterdetermined to be invalid or unreliable; or displayeddata is identified and characterized as invalid.
TRAFFIC −
a.A term used by a controller to transfer radar
identification of an aircraft to another controller forthe purpose of coordinating separation action. Trafficis normally issued:
1.In response to a handoff or point out,
2.In anticipation of a handoff or point out, or
3.In conjunction with a request for control of an
aircraft.
b.A term used by ATC to refer to one or more
aircraft.
TRAFFIC ADVISORIES − Advisories issued to alert
pilots to other known or observed air traffic whichmay be in such proximity to the position or intendedroute of flight of their aircraft to warrant theirattention. Such advisories may be based on:
a.Visual observation.
b.Observation of radar identified and nonidenti-
fied aircraft targets on an ATC radar display, or
c.Verbal reports from pilots or other facilities.
Note 1: The word “traffic” followed by additional
information, if known, is used to provide such
advisories; e.g., “T raffic, 2 o’clock, one zero miles,
southbound, eight thousand.”
Note 2: Traffic advisory service will be provided to
the extent possible depending on higher priorityduties of the controller or other limitations; e.g.,radar limitations, volume of traffic, frequency
congestion, or controller workload. Radar/
nonradar traffic advisories do not relieve the pilotof his/her responsibility to see and avoid otheraircraft. Pilots are cautioned that there are manytimes when the controller is not able to give trafficadvisories concerning all traffic in the aircraft’s
proximity; in other words, when a pilot requests or
is receiving traffic advisories, he/she should notassume that all traffic will be issued.
(Refer to AIM.)
TRAFFIC ALERT (aircraft call sign), TURN
(left/right) IMMEDIATELY, (climb/descend) ANDMAINTAIN (altitude).
(See SAFETY ALERT.)
TRAFFIC ALERT AND COLLISION A VOID-ANCE SYSTEM − An airborne collision avoidancesystem based on radar beacon signals which operates
independent of ground-based equipment. TCAS-Igenerates traffic advisories only. TCAS-II generatestraffic advisories, and resolution (collision avoid-ance) advisories in the vertical plane.
TRAFFIC INFORMATION −
(See TRAFFIC ADVISORIES.)
TRAFFIC INFORMATION SERVICE −
BROADCAST (TIS −B)− The broadcast of ATC
derived traffic information to ADS −B equipped
(1090ES or UAT) aircraft. The source of this trafficinformation is derived from ground −based air traffic
surveillance sensors, typically from radar targets.TIS−B service will be available throughout the NAS
where there are both adequate surveillance coverage(radar) and adequate broadcast coverage fromADS−B ground stations. Loss of TIS −B will occur
when an aircraft enters an area not covered by theGBT network. If this occurs in an area with adequate
surveillance coverage (radar), nearby aircraft thatremain within the adequate broadcast coverage(ADS−B) area will view the first aircraft. TIS −B may
continue when an aircraft enters an area withinadequate surveillance coverage (radar); nearbyaircraft that remain within the adequate broadcastcoverage (ADS −B) area will not view the first
aircraft.
TRAFFIC IN SIGHT − Used by pilots to inform a
controller that previously issued traffic is in sight.
(See NEGATIVE CONTACT.)
(See TRAFFIC ADVISORIES.)
TRAFFIC MANAGEMENT PROGRAM ALERT −
A term used in a Notice to Airmen (NOTAM) issuedin conjunction with a special traffic managementprogram to alert pilots to the existence of the program
and to refer them to either the Notices to Airmenpublication or a special traf fic management program
advisory message for program details. The contrac-tion TMPA is used in NOTAM text.
TRAFFIC MANAGEMENT UNIT − The entity in
ARTCCs and designated terminals directly involvedin the active management of facility traffic. Usuallyunder the direct supervision of an assistant managerfor traffic management.
TRAFFIC NO FACTOR − Indicates that the traffic
described in a previously issued traffic advisory is no
factor.
TRAFFIC NO LONGER OBSERVED − Indicates
that the traffic described in a previously issued traffic
Pilot/Controller Glossary10/12/17
PCG T−7advisory is no longer depicted on radar, but may still
be a factor.
TRAFFIC PATTERN − The traffic flow that is
prescribed for aircraft landing at, taxiing on, or taking
off from an airport. The components of a typicaltraffic pattern are upwind leg, crosswind leg,downwind leg, base leg, and final approach.
a.Upwind Leg − A flight path parallel to the
landing runway in the direction of landing.
b.Crosswind Leg − A flight path at right angles to
the landing runway off its upwind end.
c.Downwind Leg − A flight path parallel to the
landing runway in the direction opposite to landing.The downwind leg normally extends between thecrosswind leg and the base leg.
d.Base Leg − A flight path at right angles to the
landing runway off its approach end. The base legnormally extends from the downwind leg to theintersection of the extended runway centerline.
e.Final Approach. A flight path in the direction of
landing along the extended runway centerline. Thefinal approach normally extends from the base leg to
the runway. An aircraft making a straight-in approachVFR is also considered to be on final approach.
(See STRAIGHT-IN APPROACH VFR.)
(See TAXI PATTERNS.)
(See ICAO term AERODROME TRAFFIC
CIRCUIT.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
TRAFFIC SITUATION DISPLAY (TSD)− TSD is a
computer system that receives radar track data fromall 20 CONUS ARTCCs, organizes this data into amosaic display , and presents it on a computer screen.
The display allows the traffic management coordina-tor multiple methods of selection and highlighting ofindividual aircraft or groups of aircraft. The user has
the option of superimposing these aircraft positionsover any number of background displays. Thesebackground options include ARTCC boundaries, any
stratum of en route sector boundaries, fixes, airways,
military and other special use airspace, airports, andgeopolitical boundaries. By using the TSD, acoordinator can monitor any number of trafficsituations or the entire systemwide traffic flows.TRAJECTORY − A EDST representation of the path
an aircraft is predicted to fly based upon a CurrentPlan or Trial Plan.
(See EN ROUTE DECISION SUPPORT TOOL.)
TRAJECTORY MODELING − The automated pro-
cess of calculating a trajectory.
TRAJECTORY OPTIONS SET (T OS)- A TOS is an
electronic message, submitted by the operator, that isused by the Collaborative Trajectory OptionsProgram (CTOP) to manage the airspace captured in
the traffic management program. The TOS will allow
the operator to express the route and delay trade-offoptions that they are willing to accept.
TRANSCRIBED WEATHER BROADCAST − A
continuous recording of meteorological and aeronau-
tical information that is broadcast on L/MF and VORfacilities for pilots. (Provided only in Alaska.)
(Refer to AIM.)
TRANSFER OF CONTROL − That action whereby
the responsibility for the separation of an aircraft istransferred from one controller to another.
(See ICAO term TRANSFER OF CONTROL.)
TRANSFER OF CONTROL [ICAO] − Transfer of
responsibility for providing air traf fic control service.
TRANSFERRING CONTROLLER − A controller/
facility transferring control of an aircraft to anothercontroller/facility.
(See ICAO term TRANSFERRING
UNIT/CONTROLLER.)
TRANSFERRING FACILITY −
(See TRANSFERRING CONTROLLER.)
TRANSFERRING UNIT/CONTROLLER [ICAO] −
Air traffic control unit/air traffic controller in theprocess of transferring the responsibility forproviding air traffic control service to an aircraft tothe next air traffic control unit/air traffic controlleralong the route of flight.
Note: See definition of accepting unit/controller.
TRANSITION −
a.The general term that describes the change from
one phase of flight or flight condition to another; e.g.,transition from en route flight to the approach ortransition from instrument flight to visual flight.
b.A published procedure (DP Transition) used to
connect the basic DP to one of several en routeairways/jet routes, or a published procedure (STAR
Pilot/Controller Glossary 10/12/17
PCG T−8Transition) used to connect one of several en route
airways/jet routes to the basic STAR.
(Refer to DP/STAR Charts.)
TRANSITION POINT − A point at an adapted
number of miles from the vertex at which an arrivalaircraft would normally commence descent from itsen route altitude. This is the first fix adapted on thearrival speed segments.
TRANSITION WAYPOINT − The waypoint that
defines the beginning of a runway or en routetransition on an RNA V SID or STAR.
TRANSITIONAL AIRSPACE − That portion of
controlled airspace wherein aircraft change from one
phase of flight or flight condition to another.
TRANSMISSOMETER − An apparatus used to
determine visibility by measuring the transmission of
light through the atmosphere. It is the measurementsource for determining runway visual range (RVR)and runway visibility value (RVV).
(See VISIBILITY.)
TRANSMITTING IN THE BLIND − A transmis-
sion from one station to other stations incircumstances where two-way communicationcannot be established, but where it is believed that the
called stations may be able to receive thetransmission.
TRANSPONDER − The airborne radar beacon
receiver/transmitter portion of the Air Traf fic Control
Radar Beacon System (ATCRBS) which automati-cally receives radio signals from interrogators on the
ground, and selectively replies with a specific replypulse or pulse group only to those interrogationsbeing received on the mode to which it is set torespond.
(See INTERROGATOR.)
(See ICAO term TRANSPONDER.)(Refer to AIM.)TRANSPONDER [ICAO] − A receiver/transmitter
which will generate a reply signal upon properinterrogation; the interrogation and reply being ondifferent frequencies.
TRANSPONDER CODES −
(See CODES.)
TRANSPONDER OBSERVED − Phraseology used
to inform a VFR pilot the aircraft ’s assigned beacon
code and position have been observed. Specifically,this term conveys to a VFR pilot the transponderreply has been observed and its position correlated for
transit through the designated area.
TRIAL PLAN − A proposed amendment which
utilizes automation to analyze and display potentialconflicts along the predicted trajectory of the selected
aircraft.
TRSA−
(See TERMINAL RADAR SERVICE AREA.)
TSD−
(See TRAFFIC SITUATION DISPLAY.)
TURBOJET AIRCRAFT − An aircraft having a jet
engine in which the energy of the jet operates aturbine which in turn operates the air compressor.
TURBOPROP AIRCRAFT − An aircraft having a jet
engine in which the energy of the jet operates aturbine which drives the propeller.
TURN ANTICIPATION − (maneuver anticipation).
TVOR−
(See TERMINAL-VERY HIGH FREQUENCY
OMNIDIRECTIONAL RANGE STATION.)
TWEB−
(See TRANSCRIBED WEATHER BROADCAST.)
TWO-WAY RADIO COMMUNICATIONS FAIL-
URE−
(See LOST COMMUNICATIONS.)
Pilot/Controller Glossary10/12/17
PCG U−1U
UHF−
(See ULTRAHIGH FREQUENCY.)
ULTRAHIGH FREQUENCY − The frequency band
between 300 and 3,000 MHz. The bank of radiofrequencies used for military air/ground voicecommunications. In some instances this may go aslow as 225 MHz and still be referred to as UHF.
ULTRALIGHT VEHICLE − A single-occupant
aeronautical vehicle operated for sport or recreational
purposes which does not require FAA registration, an
airworthiness certificate, nor pilot certification.Operation of an ultralight vehicle in certain airspacerequires authorization from ATC
(Refer to 14 CFR Part 103.)
UNABLE − Indicates inability to comply with a
specific instruction, request, or clearance.
UNASSOCIATED − A radar target that does not
display a data block with flight identification andaltitude information.
(See ASSOCIATED.)
UNDER THE HOOD − Indicates that the pilot is
using a hood to restrict visibility outside the cockpitwhile simulating instrument flight. An appropriately
rated pilot is required in the other control seat whilethis operation is being conducted.
(Refer to 14 CFR Part 91.)
UNFROZEN − The Scheduled Time of Arrival (STA)
tags, which are still being rescheduled by the timebased flow management (TBFM) calculations. Theaircraft will remain unfrozen until the time thecorresponding estimated time of arrival (ETA) tagpasses the preset freeze horizon for that aircraft’sstream class. At this point the automatic rescheduling
will stop, and the STA becomes “frozen.”
UNICOM − A nongovernment communication facil-
ity which may provide airport information at certainairports. Locations and frequencies of UNICOMs are
shown on aeronautical charts and publications.
(See CHART SUPPLEMENT U.S.)
(Refer to AIM.)UNMANNED AIRCRAFT (UA) - A device used or
intended to be used for flight that has no onboardpilot. This device can be any type of airplane,helicopter, airship, or powered-lift aircraft.Unmanned free balloons, moored balloons, tetheredaircraft, gliders, and unmanned rockets are notconsidered to be a UA.
UNMANNED AIRCRAFT SYSTEM (UAS)- An
unmanned aircraft and its associated elements related
to safe operations, which may include controlstations (ground, ship, or air based), control links,support equipment, payloads, flight terminationsystems, and launch/recovery equipment. It consists
of three elements: unmanned aircraft, control station,and data link.
UNPUBLISHED ROUTE − A route for which no
minimum altitude is published or charted for pilotuse. It may include a direct route between NA V AIDs,
a radial, a radar vector, or a final approach coursebeyond the segments of an instrument approachprocedure.
(See PUBLISHED ROUTE.)
(See ROUTE.)
UNRELIABLE (GPS/WAAS) − An advisory to
pilots indicating the expected level of service of theGPS and/or W AAS may not be available. Pilots must
then determine the adequacy of the signal for desired
use.
UPWIND LEG −
(See TRAFFIC PATTERN.)
URGENCY − A condition of being concerned about
safety and of requiring timely but not immediateassistance; a potential distress condition.
(See ICAO term URGENCY.)
URGENCY [ICAO] − A condition concerning the
safety of an aircraft or other vehicle, or of person onboard or in sight, but which does not requireimmediate assistance.
USAFIB−
(See ARMY AVIATION FLIGHT INFORMATION
BULLETIN.)
Pilot/Controller Glossary10/12/17
PCG V−1V
VASI−
(See VISUAL APPROACH SLOPE INDICATOR.)
VCOA−
(See VISUAL CLIMB OVER AIRPORT.)
VDP−
(See VISUAL DESCENT POINT.)
VECTOR − A heading issued to an aircraft to provide
navigational guidance by radar.
(See ICAO term RADAR VECTORING.)
VERIFY − Request confirmation of information;
e.g., “verify assigned altitude.”
VERIFY SPECIFIC DIRECTION OF TAKEOFF
(OR TURNS AFTER TAKEOFF) − Used by ATC to
ascertain an aircraft’s direction of takeoff and/ordirection of turn after takeoff. It is normally used for
IFR departures from an airport not having a controltower. When direct communication with the pilot isnot possible, the request and information may berelayed through an FSS, dispatcher, or by other
means.
(See IFR TAKEOFF MINIMUMS AND
DEPARTURE PROCEDURES.)
VERTEX − The last fix adapted on the arrival speed
segments. Normally, it will be the outer marker of the
runway in use. However, it may be the actualthreshold or other suitable common point on theapproach path for the particular runway configura-tion.
VERTEX TIME OF ARRIV AL − A calculated time of
aircraft arrival over the adapted vertex for the runway
configuration in use. The time is calculated via theoptimum flight path using adapted speed segments.
VERTICAL NA VIGATION (VNA V)– A function of
area navigation (RNA V) equipment which calculates,
displays, and provides vertical guidance to a profileor path.
VERTICAL SEPARATION − Separation between
aircraft expressed in units of vertical distance.
(See SEPARATION.)
VERTICAL TAKEOFF AND LANDING AIR-CRAFT− Aircraft capable of vertical climbs and/ordescents and of using very short runways or small
areas for takeoff and landings. These aircraft include,
but are not limited to, helicopters.
(See SHORT TAKEOFF AND LANDING
AIRCRAFT.)
VERY HIGH FREQUENCY − The frequency band
between 30 and 300 MHz. Portions of this band, 108
to 118 MHz, are used for certain NA V AIDs; 118 to136 MHz are used for civil air/ground voicecommunications. Other frequencies in this band areused for purposes not related to air traffic control.
VERY HIGH FREQUENCY OMNIDIRECTION-
AL RANGE STA TION−
(See VOR.)
VERY LOW FREQUENCY − The frequency band
between 3 and 30 kHz.
VFR−
(See VISUAL FLIGHT RULES.)
VFR AIRCRAFT − An aircraft conducting flight in
accordance with visual flight rules.
(See VISUAL FLIGHT RULES.)
VFR CONDITIONS − Weather conditions equal to
or better than the minimum for flight under visualflight rules. The term may be used as an ATCclearance/instruction only when:
a.An IFR aircraft requests a climb/descent in
VFR conditions.
b.The clearance will result in noise abatement
benefits where part of the IFR departure route doesnot conform to an FAA approved noise abatementroute or altitude.
c.A pilot has requested a practice instrument
approach and is not on an IFR flight plan.
Note: All pilots receiving this authorization must
comply with the VFR visibility and distance fromcloud criteria in 14 CFR Part 91. Use of the termdoes not relieve controllers of their responsibility to
separate aircraft in Class B and Class C airspace
or TRSAs as required by FAA Order JO 7110.65.
When used as an ATC clearance/instruction, theterm may be abbreviated “VFR;” e.g., “MAINTAINVFR,” “CLIMB/DESCEND VFR,” etc.
VFR FLIGHT −
(See VFR AIRCRAFT.)
Pilot/Controller Glossary 10/12/17
PCG V−2VFR MILITARY TRAINING ROUTES − Routes
used by the Department of Defense and associatedReserve and Air Guard units for the purpose ofconducting low-altitude navigation and tacticaltraining under VFR below 10,000 feet MSL atairspeeds in excess of 250 knots IAS.
VFR NOT RECOMMENDED − An advisory
provided by a flight service station to a pilot duringa preflight or inflight weather briefing that flightunder visual flight rules is not recommended. To begiven when the current and/or forecast weatherconditions are at or below VFR minimums. It doesnot abrogate the pilot’s authority to make his/her owndecision.
VFR-ON-TOP − ATC authorization for an IFR
aircraft to operate in VFR conditions at anyappropriate VFR altitude (as specified in 14 CFR and
as restricted by ATC). A pilot receiving thisauthorization must comply with the VFR visibility,distance from cloud criteria, and the minimum IFRaltitudes specified in 14 CFR Part 91. The use of this
term does not relieve controllers of their responsibil-ity to separate aircraft in Class B and Class C airspace
or TRSAs as required by FAAO JO 7110.65.
VFR TERMINAL AREA CHARTS −
(See AERONAUTICAL CHART.)
VFR WA YPOINT−
(See WAYPOINT.)
VHF−
(See VERY HIGH FREQUENCY.)
VHF OMNIDIRECTIONAL RANGE/TACTICAL
AIR NA VIGA TION−
(See VORTAC.)
VIDEO MAP − An electronically displayed map on
the radar display that may depict data such as airports,heliports, runway centerline extensions, hospitalemergency landing areas, NA V AIDs and fixes,reporting points, airway/route centerlines, bound-aries, handoff points, special use tracks, obstructions,
prominent geographic features, map alignmentindicators, range accuracy marks, minimum vector-ing altitudes.
VISIBILITY − The ability, as determined by
atmospheric conditions and expressed in units ofdistance, to see and identify prominent unlighted
objects by day and prominent lighted objects bynight. Vi sibility is reported as statute miles, hundreds
of feet or meters.
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
a.Flight Visibility− The average forward horizon-
tal distance, from the cockpit of an aircraft in flight,at which prominent unlighted objects may be seenand identified by day and prominent lighted objectsmay be seen and identified by night.
b.Ground Visibility − Prevailing horizontal visi-
bility near the earth’s surface as reported by theUnited States National Weather Service or anaccredited observer.
c.Prevailing Visibility − The greatest horizontal
visibility equaled or exceeded throughout at least halfthe horizon circle which need not necessarily becontinuous.
d.Runway Visibility V alue (RVV) − The visibility
determined for a particular runway by a transmis-someter. A meter provides a continuous indication of
the visibility (reported in miles or fractions of miles)for the runway. RVV is used in lieu of prevailingvisibility in determining minimums for a particularrunway.
e.Runway Visual Range (RVR) − An instrumen-
tally derived value, based on standard calibrations,that represents the horizontal distance a pilot will see
down the runway from the approach end. It is basedon the sighting of either high intensity runway lightsor on the visual contrast of other targets whicheveryields the greater visual range. RVR, in contrast toprevailing or runway visibility, is based on what apilot in a moving aircraft should see looking down the
runway. RVR is horizontal visual range, not slantvisual range. It is based on the measurement of atransmissometer made near the touchdown point ofthe instrument runway and is reported in hundreds offeet. RVR is used in lieu of RVV and/or prevailingvisibility in determining minimums for a particularrunway.
1.Touchdown RVR
− The RVR visibility
readout values obtained from RVR equipmentserving the runway touchdown zone.
2.Mid-RVR
− The RVR readout values obtained
from RVR equipment located midfield of the runway.
Pilot/Controller Glossary10/12/17
PCG V−33.Rollout RVR − The RVR readout values
obtained from RVR equipment located nearest therollout end of the runway.
(See ICAO term FLIGHT VISIBILITY.)
(See ICAO term GROUND VISIBILITY.)
(See ICAO term RUNWAY VISUAL RANGE.)
(See ICAO term VISIBILITY.)
VISIBILITY [ICAO]− The ability, as determined by
atmospheric conditions and expressed in units ofdistance, to see and identify prominent unlightedobjects by day and prominent lighted objects bynight.
a.Flight Visibility −The visibility forward from
the cockpit of an aircraft in flight.
b.Ground Visibility −The visibility at an aero-
drome as reported by an accredited observer.
c.Runway Visual Range [RVR] −The range over
which the pilot of an aircraft on the centerline of arunway can see the runway surface markings or thelights delineating the runway or identifying itscenterline.
VISUAL APPROACH − An approach conducted on
an instrument flight rules (IFR) flight plan whichauthorizes the pilot to proceed visually and clear ofclouds to the airport. The pilot must, at all times, have
either the airport or the preceding aircraft in sight.This approach must be authorized and under thecontrol of the appropriate air traffic control facility.Reported weather at the airport must be ceiling at orabove 1,000 feet and visibility of 3 miles or greater.
(See ICAO term VISUAL APPROACH.)
VISUAL APPROACH [ICAO] − An approach by an
IFR flight when either part or all of an instrumentapproach procedure is not completed and theapproach is executed in visual reference to terrain.
VISUAL APPROACH SLOPE INDICATOR −
(See AIRPORT LIGHTING.)
VISUAL CLIMB OVER AIRPORT (VCOA) − A
departure option for an IFR aircraft, operating invisual meteorological conditions equal to or greaterthan the specified visibility and ceiling, to visuallyconduct climbing turns over the airport to thepublished “climb−to” altitude from which to proceed
with the instrument portion of the departure. VCOAprocedures are developed to avoid obstacles greaterthan 3 statute miles from the departure end of therunway as an alternative to complying with climb
gradients greater than 200 feet per nautical mile.Pilots are responsible to advise ATC as early aspossible of the intent to fly the VCOA option prior to
departure. These textual procedures are published inthe ‘Take−Off Minimums and (Obstacle) Departure
Procedures’ section of the Terminal ProceduresPublications and/or appear as an option on a Graphic
ODP.
(See AIM.)
VISUAL DESCENT POINT − A defined point on the
final approach course of a nonprecision straight-inapproach procedure from which normal descent from
the MDA to the runway touchdown point may becommenced, provided the approach threshold of that
runway, or approach lights, or other markingsidentifiable with the approach end of that runway are
clearly visible to the pilot.
VISUAL FLIGHT RULES − Rules that govern the
procedures for conducting flight under visual
conditions. The term “VFR” is also used in theUnited States to indicate weather conditions that areequal to or greater than minimum VFR requirements.
In addition, it is used by pilots and controllers toindicate type of flight plan.
(See INSTRUMENT FLIGHT RULES.)
(See INSTRUMENT METEOROLOGICAL
CONDITIONS.)
(See VISUAL METEOROLOGICAL
CONDITIONS.)
(Refer to 14 CFR Part 91.)
(Refer to AIM.)
VISUAL HOLDING − The holding of aircraft at
selected, prominent geographical fixes which can be
easily recognized from the air.
(See HOLDING FIX.)
VISUAL METEOROLOGICAL CONDITIONS −
Meteorological conditions expressed in terms ofvisibility, distance from cloud, and ceiling equal to or
better than specified minima.
(See INSTRUMENT FLIGHT RULES.)
(See INSTRUMENT METEOROLOGICAL
CONDITIONS.)
(See VISUAL FLIGHT RULES.)
VISUAL SEGMENT −
(See PUBLISHED INSTRUMENT APPROACH
PROCEDURE VISUAL SEGMENT.)
Pilot/Controller Glossary 10/12/17
PCG V−4VISUAL SEPARATION − A means employed by
ATC to separate aircraft in terminal areas and en routeairspace in the NAS. There are two ways to ef fect this
separation:
a.The tower controller sees the aircraft involved
and issues instructions, as necessary, to ensure thatthe aircraft avoid each other.
b.A pilot sees the other aircraft involved and upon
instructions from the controller provides his/her own
separation by maneuvering his/her aircraft asnecessary to avoid it. This may involve followinganother aircraft or keeping it in sight until it is nolonger a factor.
(See SEE AND AVOID.)
(Refer to 14 CFR Part 91.)
VLF−
(See VERY LOW FREQUENCY.)
VMC−
(See VISUAL METEOROLOGICAL
CONDITIONS.)
VOICE SWI TCHING AND CONTROL SYSTEM −
The VSCS is a computer controlled switching systemthat provides air traffic controllers with all voicecircuits (air to ground and ground to ground)necessary for air traffic control.
(See VOICE SWITCHING AND CONTROL
SYSTEM.)
(Refer to AIM.)
VOR− A ground-based electronic navigation aid
transmitting very high frequency navigation signals,360 degrees in azimuth, oriented from magneticnorth. Used as the basis for navigation in the National
Airspace System. The VOR periodically identifiesitself by Morse Code and may have an additionalvoice identification feature. V oice features may beused by ATC or FSS for transmitting instructions/information to pilots.
(See NAVIGATIONAL AID.)
(Refer to AIM.)
VOR TEST SIGNAL −
(See VOT.)VORTAC − A navigation aid providing VOR
azimuth, TACAN azimuth, and TACAN distancemeasuring equipment (DME) at one site.
(See DISTANCE MEASURING EQUIPMENT.)
(See NAVIGATIONAL AID.)(See TACAN.)(See VOR.)(Refer to AIM.)
VORTICES − Circular patterns of air created by the
movement of an airfoil through the air whengenerating lift. As an airfoil moves through theatmosphere in sustained flight, an area of area of low
pressure is created above it. The air flowing from thehigh pressure area to the low pressure area around and
about the tips of the airfoil tends to roll up into tworapidly rotating vortices, cylindrical in shape. Thesevortices are the most predominant parts of aircraftwake turbulence and their rotational force isdependent upon the wing loading, gross weight, andspeed of the generating aircraft. The vortices frommedium to super aircraft can be of extremely highvelocity and hazardous to smaller aircraft.
(See AIRCRAFT CLASSES.)
(See WAKE TURBULENCE.)
(Refer to AIM.)
VOT− A ground facility which emits a test signal to
check VOR receiver accuracy. Some VOTs areavailable to the user while airborne, and others arelimited to ground use only.
(See CHART SUPPLEMENT U.S.)
(Refer to 14 CFR Part 91.)(Refer to AIM.)
VR−
(See VFR MILITARY TRAINING ROUTES.)
VSCS−
(See VOICE SWITCHING AND CONTROL
SYSTEM.)
VTA−
(See VERTEX TIME OF ARRIVAL.)
VTOL AIRCRAFT −
(See VERTICAL TAKEOFF AND LANDING
AIRCRAFT.)
Pilot/Controller Glossary10/12/17
PCG W−1W
WA−
(See AIRMET.)
(See WEATHER ADVISORY.)
WAAS−
(See WIDE-AREA AUGMENTATION SYSTEM.)
WAKE TURBULENCE − Phenomena resulting from
the passage of an aircraft through the atmosphere.The term includes vortices, thrust stream turbulence,jet blast, jet wash, propeller wash, and rotor washboth on the ground and in the air.
(See AIRCRAFT CLASSES.)
(See JET BLAST.)(See VORTICES.)(Refer to AIM.)
WARNING AREA −
(See SPECIAL USE AIRSPACE.)
WAYPOINT − A predetermined geographical posi-
tion used for route/instrument approach definition,progress reports, published VFR routes, visualreporting points or points for transitioning and/orcircumnavigating controlled and/or special useairspace, that is defined relative to a VORTAC station
or in terms of latitude/longitude coordinates.
WEATHER ADVISORY − In aviation weather
forecast practice, an expression of hazardous weather
conditions not predicted in the area forecast, as theyaffect the operation of air traffic and as prepared bythe NWS.
(See AIRMET.)
(See SIGMET.)
WEATHER RECONNAISSANCE AREA (WRA) −
A WRS is airspace with defined dimensions and
published by Notice to Airmen, which is established
to support weather reconnaissance/research flights.
Air traffic control services are not provided within
WRAs. Only participating weather reconnaissance/
research aircraft from the 53rd Weather
Reconnaissance Squadron and National Oceanic and
Atmospheric Administration Aircraft Operations
Center are permitted to operate within a WRA. A
WRA may only be established in airspace within U.S.
Flight Information Regions outside of U.S. territorial
airspace.WHEN ABLE−
a.In conjunction with ATC instructions, gives the
pilot the latitude to delay compliance until acondition or event has been reconciled. Unlike “pilot
discretion,” when instructions are prefaced “whenable,” the pilot is expected to seek the firstopportunity to comply.
b.In conjunction with a weather deviation
clearance, requires the pilot to determine when he/she
is clear of weather, then execute ATC instructions.
c.Once a maneuver has been initiated, the pilot is
expected to continue until the specifications of theinstructions have been met. “When able,” should not
be used when expeditious compliance is required.
WIDE-AREA AUGMENTATION SYSTEM
(WAAS)− The W AAS is a satellite navigation system
consisting of the equipment and software whichaugments the GPS Standard Positioning Service(SPS). The WAAS provides enhanced integrity,accuracy, availability, and continuity over and above
GPS SPS. The differential correction functionprovides improved accuracy required for precisionapproach.
WIDE AREA MULTILATERATION (WAM)– A
distributed surveillance technology which mayutilize any combination of signals from Air TrafficControl Radar Beacon System (ATCRBS) (Modes A
and C) and Mode S transponders, and ADS-Btransmissions. Multiple geographically dispersedground sensors measure the time-of-arrival of thetransponder messages. Aircraft position is deter-mined by joint processing of thetime-dif ference-of-arrival (TDOA) measurements
computed between a reference and the groundstations’ measured time-of-arrival.
WILCO− I have received your message, understand
it, and will comply with it.
WIND GRID DISPLAY − A display that presents the
latest forecasted wind data overlaid on a map of theARTCC area. Wind data is automatically entered and
updated periodically by transmissions from theNational Weather Service. Winds at specificaltitudes, along with temperatures and air pressurecan be viewed.
Pilot/Controller Glossary 10/12/17
PCG W−2WIND SHEAR− A change in wind speed and/or wind
direction in a short distance resulting in a tearing orshearing ef fect. It can exist in a horizontal or vertical
direction and occasionally in both.
WIND SHEAR ESCAPE– An unplanned abortive
maneuver initiated by the pilot in command (PIC) as
a result of onboard cockpit systems. Wind shearescapes are characterized by maximum thrust climbs
in the low altitude terminal environment until windshear conditions are no longer detected.
WING TIP VORTICES −
(See VORTICES.)WORDS TWICE −
a.As a request: “Communication is difficult.
Please say every phrase twice.”
b.As information: “Since communications are
difficult, every phrase in this message will be spoken
twice.”
WS−
(See SIGMET.)
(See WEATHER ADVISORY.)
WST−
(See CONVECTIVE SIGMET.)
(See WEATHER ADVISORY.)
10/12/17 AIM
Index I−1INDEX
[References are to page numbers]
A
Accident, Aircraft, Reporting, 7 −6−1
Accident Cause Factors, 7 −5−1
Adherence to Clearance, 4 −4−5
ADS−B. See Automatic Dependent Broadcast Services
ADS−R. See Automatic Dependent
Surveillance −Rebroadcast
Advisories
Braking Action, 4 −3−12
Inflight Aviation Weather, 7 −1−9
Minimum Fuel, 5 −5−7
Traffic, 5−5−5
Aerobatic Flight, 8 −1−8
Aerodrome Forecast (T AF), 7−1−68, 7−1−69, 7−1−70
Aeronautical
Charts, 9−1−1
Publications, 9 −1−1
Aeronautical Light Beacons, 2 −2−1
AFIS. See Automatic Flight Information Service
AHRS. See Attitude Heading Reference System
Air Ambulance Flights, 4 −2−4
Air Defense Identification Zones, 5 −6−13
Air Route Surveillance Radar, 4 −5−7
Air Route Traffic Control Centers, 4 −1−1
Air Traffic Control
Aircraft Separation, 4 −4−1
Clearances, 4 −4−1
Pilot Services, 4 −1−1
Air Route Traffic Control Centers, 4 −1−1
Airport Reservations, 4 −1−18
Approach Control Service, Arriving VFR Aircraft,
4−1−2
Automatic Terminal Information Service, 4 −1−7
Communications, Release of IFR Aircraft, Airports
without Operating Control Tower, 4 −1−1
Control T owers, 4−1−1
Flight Service Stations, 4 −1−1
Ground Vehicle Operations, 4 −1−6
IFR Approaches, 4 −1−6
Operation Rain Check, 4 −1−2
Radar Assistance to VFR Aircraft, 4 −1−11
Radar Traffic Information Service, 4 −1−9
Recording and Monitoring, 4 −1−1Safety Alert, 4 −1−10
Terminal Radar Services for VFR Aircraft, 4 −1−12
Tower En Route Control, 4 −1−14
Traffic Advisory Practices, Airports Without
Operating Control T owers, 4−1−2
Transponder Operation, 4 −1−15
Unicom, Use for ATC Purposes, 4 −1−7
Unicom/Multicom, 4 −1−6
Air Traffic Control Radar Beacon System, 4 −1−15,
4−5−2
Aircraft
Arresting Devices, 2 −3−30
Call Signs, 4 −2−3
Lights, Use in Airport Operations, 4 −3−26
Unmanned, 7 −5−2
VFR, Emergency Radar Service, 6 −2−1
Aircraft Conflict Alert, 4 −1−11
Airport
Aids, Marking, 2 −3−1
Holding Position, 2 −3−12
Pavement, 2 −3−1
Holding Position, 2 −3−1
Other, 2−3−1
Runway, 2 −3−1
Taxiway, 2 −3−1
Airport Advisory/Information Services, 3 −5−1
Lighting Aids, 2 −1−1
Local Airport Advisory (LAA), 4 −1−4
Operations, 4 −3−1
Communications, 4 −3−19
Exiting the Runway, After Landing, 4 −3−24
Flight Check Aircraft, In Terminal Areas, 4 −3−26
Flight Inspection, 4 −3−26
Gate Holding, Departure Delays, 4 −3−20
Intersection Takeof fs, 4−3−15
Low Approach, 4 −3−18
Low Level Wind Shear/Microburst Detection
Systems, 4 −3−12
Option Approach, 4 −3−25
Signals, Hand, 4 −3−27
Taxi During Low Visibility, 4 −3−23
Traffic Control Light Signals, 4 −3−18
Traffic Patterns, 4 −3−1, 4−3−2
Use of Aircraft Lights, 4 −3−26
Use of Runways, 4 −3−7
VFR Flights in Terminal Areas, 4 −3−20
VFR Helicopter at Controlled Airports, 4 −3−20
With Operating Control Tower, 4 −3−1
Without Operating Control Tower, 4 −3−6
Remote Airport Advisory (RAA), 3 −5−1
10/12/17 AIM
Index I−2[References are to page numbers]
Remote Airport Information Service (RAIS), 3 −5−1,
4−1−4
Signs, 2−3−1, 2−3−19
Destination, 2 −3−28
Direction, 2 −3−25
Information, 2 −3−29
Location, 2 −3−23
Mandatory Instruction, 2 −3−20
Runway Distance Remaining, 2 −3−29
Airport Reservations, 4 −1−18
Airport Surface Detection Equipment, 4 −5−7
Airport Surface Surveillance Capability, 4 −5−7
Airport Surveillance Radar, 4 −5−7
Airspace, 3 −1−1
Basic VFR Weather Minimums, 3 −1−1
Class D, 3 −2−8
Class E, 3 −2−9
Class G, 3 −3−1
Controlled, 3 −2−1
Advisories, Traf fic, 3−2−1
Alerts, Safety, 3 −2−1
Class A, 3 −2−2
Class B, 3 −2−2
Class C, 3 −2−4
IFR Requirements, 3 −2−1
IFR Separation, 3 −2−1
Parachute Jumps, 3 −2−2
Ultralight Vehicles, 3 −2−2
Unmanned Free Balloons, 3 −2−2
VFR Requirements, 3 −2−1
Flight Levels, 3 −1−2
General Dimensions, Segments, 3 −1−1
Military Training Routes, 3 −5−1
Other Areas, 3 −5−1
Parachute Jumping, 3 −5−5
Special Use, 3 −4−1
Temporary Flight Restrictions, 3 −5−2
Terminal Radar Service Areas, 3 −5−9
VFR Cruising Altitudes, 3 −1−2
VFR Routes, Published, 3 −5−5
Class B Airspace, VFR Transition Routes, 3 −5−7
VFR Corridors, 3 −5−7
VFR Flyways, 3 −5−5
Airway, 5 −3−5
Airways, Course Changes, 5 −3−7
Alcohol, 8 −1−1
Alert, Safety, 4 −1−10, 5−5−3
Alert Areas, 3 −4−2Alignment of Elements Approach Slope Indicator,
2−1−5
Alphabet, Phonetic, 4 −2−5
ALS. See Approach Light Systems
Altimeter
Density Altitude, 7 −5−4
Errors, 7−2−3
Setting, 7 −2−1
High Barometric Pressure, 7 −2−4
Low Barometric Pressure, 7 −2−4
Altitude
Automatic Reporting, 4 −1−16
Effects, 8 −1−3
Hypoxia, 8 −1−3
High Altitude Destinations, 5 −1−27
Mandatory, 5 −4−7
Maximum, 5 −4−7
Minimum, 5 −4−7
Ambulance, Air, 4 −2−4
Amended Clearances, 4 −4−2
Approach
Advance Information, Instrument Approach, 5 −4−4
Approach Control, 5 −4−3
Clearance, 5 −4−25
Contact, 5 −4−63, 5−5−2
Instrument, 5 −5−2
Instrument Approach Procedure, Charts, 5 −4−5
Instrument Approach Procedures, 5 −4−27
Low, 4−3−18
Minimums, 5 −4−53
Missed, 5 −4−56, 5−5−3
No−Gyro, 5−4−36
Option, 4−3−25
Overhead Approach Maneuver, 5 −4−64
Precision, 5 −4−35
Surveillance, 5 −4−35
Visual, 5−4−62, 5−5−5
Approach Control Service, VFR Arriving Aircraft,
4−1−2
Approach Light Systems, 2 −1−1
Approaches
IFR, 4−1−6
Parallel Runways, ILS/RNA V/GLS, 5 −4−36
Radar, 5−4−35
Timed, 5−4−32
Area Navigation (RNA V), 5−1−14, 5−3−6, 5−5−7See
also Area Navigation
Area Navigation (RNAV) Routes, 5 −3−6
10/12/17 AIM
Index I−3[References are to page numbers]
ARFF (Aircraft Rescue and Fire Fighting) Emergency
Hand Signals, 6 −5−1
ARFF (Aircraft Rescue and Fire Fighting) Radio Call
Sign, 6−5−1
Arresting Devices, Aircraft, 2 −3−30
ARSR. See Air Route Surveillance Radar
ARTCC. See Air Route Traffic Control Centers
ASDE−X. See Airport Surface Detection
Equipment −Model X
Ash, Volcanic, 7 −5−7
ASOS. See Automated Surface Observing System
ASR. See Airport Surveillance Radar; Surveillance
Approach
ASSC, 4−5−7
ATCRBS. See Air Traffic Control Radar Beacon
System
ATCT. See Control Towers
ATIS. See Automatic Terminal Information Service
Attitude Heading Reference System (AHRS), 1 −1−16
Authority, Statutory, 1 −1−1
Automated Surface Observing System (ASOS), 4 −3−31,
7−1−27
Automated Weather Observing System (AWOS),
4−3−31, 7−1−24
Automated Weather Sensor System (AWSS), 4 −3−31
Automated Weather Sensor System (AWSS), 7 −1−27
Automatic Altitude Reporting, 4 −1−16
Automatic Dependent Surveillance −Broadcast Services,
4−5−14
Automatic Dependent Surveillance −Rebroadcast,
4−5−21
Automatic Flight Information Service (AFIS) − Alaska
FSSs Only, 4 −1−8
Automatic Terminal Information Service, 4 −1−7
AWOS. See Automated Weather Observing System
B
Balloons, Unmanned, 7 −5−2
Free, 3−2−2
BeaconAeronautical Light, 2 −2−1
Code, 2−2−1
Marker, 1 −1−10
Nondirectional Radio, 1 −1−1
Beacons, Airport/Heliport, 2 −1−14
Bird
Bird Strike
Reduction, 7 −4−1
Reporting, 7 −4−1
Hazards, 7 −4−1
Migratory, 7 −4−1
Bird/Other Wildlife Strike Reporting, Form. See
Appendix 1
Braking Action Advisories, 4 −3−12
Braking Action Reports, 4 −3−12
Briefing, Preflight, 7 −1−7
C
Call Signs
Aircraft, 4 −2−3
Ground Station, 4 −2−4
Carbon Monoxide Poisoning, 8 −1−5
CAT. See Clear Air Turbulence
CDR. See Coded Depature Route
Changeover Points, 5 −3−8
Charted Visual Flight Procedures, 5 −4−63
Charts, Aeronautical, 9 −1−1
Class A Airspace, 3 −2−2
Definition, 3 −2−2
Operating Rules, 3 −2−2
Pilot/Equipment Requirements, 3 −2−2
Class B Airspace, 3 −2−2
ATC Clearances, 3 −2−3
Definition, 3 −2−2
Flight Procedures, 3 −2−3
Mode C Veil, 3 −2−3
Operating Rules, 3 −2−2
Pilot/Equipment Requirements, VFR Operations,
3−2−2
Proximity Operations, 3 −2−4
Separation, 3 −2−3
VFR Transition Routes, 3 −5−7
Class C Airspace, 3 −2−4
Air Traffic Services, 3 −2−5
Aircraft Separation, 3 −2−5
10/12/17 AIM
Index I−4[References are to page numbers]
Definition, 3 −2−4
Operating Rules, 3 −2−4
Outer Area, 3 −2−5
Pilot/Equipment Requirements, 3 −2−4
Secondary Airports, 3 −2−6
Class D Airspace, 3 −2−8
Definition, 3 −2−8
Operating Rules, 3 −2−8
Pilot/Equipment Requirements, 3 −2−8
Separation for VFR Aircraft, 3 −2−9
Class E Airspace, 3 −2−9
Definition, 3 −2−9
Operating Rules, 3 −2−9
Pilot/Equipment Requirements, 3 −2−9
Separation for VFR Aircraft, 3 −2−10
Types, 3−2−9
Vertical Limits, 3 −2−9
Class G Airspace, 3 −3−1
IFR Requirements, 3 −3−1
VFR Requirements, 3 −3−1
Clear Air Turbulence, 7 −1−46
Clearance
Abbreviated IFR Departure, 5 −2−3
Adherence, 4 −4−5
Air Traffic, 5 −5−1
Air Traffic Control, 4 −4−1
Amended, 4 −4−2
Approach, 5 −4−25
IFR, VFR −on−Top, 4−4−4
IFR Flights, 4 −4−5
Issuance, Pilot Responsibility, 4 −4−4
Items, 4−4−1
Altitude Data, 4 −4−2
Clearance Limit, 4 −4−1
Departure Procedure, 4 −4−1
Holding Instructions, 4 −4−2
Route of Flight, 4 −4−1
Pre−Taxi, 5−2−1
Prefix, 4−4−1
Taxi, 5−2−2
VFR Flights, 4 −4−5
Void Times, 5 −2−4
Clearances, Special VFR Clearances, 4 −4−3
Clearing Procedures, Visual, 4 −4−11
Coded Depature Route, 4 −4−3
Cold Temperature Operations, 5 −1−31
Pilot Responsibilities, 5 −5−2, 5−5−3
Collision, Avoidance, Judgment, 8 −1−8Communication, Radio
Contact, Reestablishing, 6 −4−2
Two−way Failure, 6 −4−1
IFR Conditions, 6 −4−1
Transponder Usage, 6 −4−2
VFR Conditions, 6 −4−1
Communications
ARTCC, 5 −3−1
Additional Reports, 5 −3−4
Position Reporting, 5 −3−3
Distress, 6 −3−1
Radio, 4−2−1
Phonetic Alphabet, 4 −2−5
Release, 4 −1−1
Urgency, 6 −3−1
Conflict Alert, Aircraft, 4 −1−11
Contact Approach, 5 −4−63
Contact Procedures, 4 −2−1
Initial Contact, 4 −2−1
Control of Lighting Systems, 2 −1−11
Control T owers, 4−1−1
Controlled Firing Areas, 3 −4−2
Controller, Responsibility, 5 −3−8, 5−4−62, 5−5−1
COP. See Changeover Points
CORONA, 7 −5−9
Course Lights, 2 −2−1
CVFP . See Charted Visual Flight Procedures
D
Decompression Sickness, 8 −1−4
Density Altitude, Ef fects, 7−5−4
Departure, Restrictions, 5 −2−4
Departure Control, 5 −2−5
Departures, Instrument, 5 −5−7
Discrete Emergency Frequency, 6 −5−1
Distance Measuring Equipment, 1 −1−5, 1−1−10,
5−3−13
Distress, 6 −3−1
Ditching Procedures, 6 −3−3
DME. See Distance Measuring Equipment
Doppler Radar, 1 −1−16
10/12/17 AIM
Index I−5[References are to page numbers]
E
Ear Block, 8 −1−4
EFVS. See Enhanced Flight Vision Systems
ELT. See Emergency Locator Transmitters
Emergency, 6 −1−1
Air Piracy, 6 −3−6
Airborne Aircraft Inspection, 7 −5−8
Aircraft, Overdue, 6 −2−5
Body Signals, 6 −2−6
Ditching Procedures, 6 −3−3
Explosives Detection, FAA K −9 Team Program,
6−2−3
Fuel Dumping, 6 −3−7
Inflight Monitoring and Reporting, 6 −2−3
Intercept and Escort, 6 −2−1
Locator Transmitters, 6 −2−2
Obtaining Assistance, 6 −3−1
Pilot Authority, 6 −1−1
Pilot Responsibility, 6 −1−1
Request Assistance Immediately, 6 −1−1
Search and Rescue, 6 −2−4
Services, 6 −2−1
Radar Service for VFR Aircraft in Difficulty,
6−2−1
Survival Equipment, 6 −2−6
Transponder Operation, 6 −2−1
VFR Search and Rescue Protection, 6 −2−5
Emergency Locator Transmitter, 6 −2−2
Enhanced Flight Vision Systems, 5 −4−58
Escort, 6−2−1
Explosives, FAA K −9 Detection Team Program, 6 −2−3
F
FAROS. See Final Approach Runway Occupancy
Signal (FAROS)
Final Approach Runway Occupancy Signal (FAROS),
2−1−9
Final Guard, 3 −5−1
FIS−B. See Flight Information Service −Broadcast
Fitness, Flight
Alcohol, 8 −1−1
Emotion, 8 −1−2
Fatigue, 8 −1−2
Hypoxia, 8 −1−3
Stress, 8−1−2Flight
Aerobatic, 8 −1−8
Fitness, 8 −1−1
Illusions, 8 −1−5
Over National Forests, 7 −4−1
Over National Parks, 7 −4−1
Over National Refuges, 7 −4−1
Safety, Meteorology, 7 −1−1
Vision, 8−1−6
Flight Check Aircraft, 4 −3−26
Flight Information Service −Broadcast, 4 −5−19
Flight Information Services, 7 −1−20
Flight Inspections Aircraft, 4 −3−26
Flight Management System, 1 −2−4, 5−1−12
Flight Plan
Change, 5 −1−30
Proposed Departure Time, 5 −1−30
Closing
DVFR, 5−1−30
VFR, 5−1−30
Composite, VFR/IFR, 5 −1−11
DVFR Flights, 5 −1−10
Explanation of IFR, 5 −1−15
Explanation of VFR, 5 −1−9
Form 7233 −1, 5−1−9, 5−1−16
IFR, Canceling, 5 −1−30
IFR Flights, Domestic, 5 −1−11
VFR Flights, 5 −1−7
Flight Restrictions, Temporary, 3 −5−2
Flight Service Stations, 4 −1−1
Flights, Outside the United States, 5 −1−28
Flying, Mountain, 7 −5−3
FMS. See Flight Management System
Forms
Bird Strike Incident/Ingestion Report, Appendix 1 −1
Volcanic Activity Reporting Form, Appendix 2 −1
Frequency, Instrument Landing System, 1 −1−11
FSS. See Flight Service Stations
Fuel Dumping, 6 −3−7
G
Gate Holding, 4 −3−20
GBAS. See Ground Based Augmentation System
Glideslope, Visual Indicators, 2 −1−1
Global Navigation Satellite System, 1 −1−15, 1−1−34,
5−1−12
10/12/17 AIM
Index I−6[References are to page numbers]
Global Positioning System, 1 −1−16
GNSS. See Global Navigation Satellite System
GPS. See Global Positioning System
Graphical Forecasts for A viation (GF A), 7−1−5
Ground Based Augmentation System (GBAS), 1 −1−35
Ground Based Augmentation System (GBAS) Landing
System (GLS), 1 −1−34
Ground Station, Call Signs, 4 −2−4
Ground Vehicle Operations, 4 −1−6
Gulf of Mexico Grid System, 10 −1−6
H
Half−Way Signs, 7 −5−5
Hand Signals, 4 −3−27
Hazard
Antenna Tower, 7 −5−1
Bird, 7−4−1
Flight
Obstructions to Flight, 7 −5−1
Potential, 7 −5−1
VFR in Congested Areas, 7 −5−1
Ground Icing Conditions, 7 −5−12
Mountain Flying, 7 −5−3
Overhead Wires, 7 −5−2
Thermal Plumes, 7 −5−13
Unmanned Balloons, 7 −5−2
Volcanic Ash, 7 −5−7
HDTA. See High Density Traffic Airports
Helicopter
IFR Operations, 10 −1−1
Landing Area Markings, 2 −3−19
VFR Operations at Controlled Airports, 4 −3−20
Special Operations, 10 −2−1
Wake Turbulence, 7 −3−6
High Density Traffic Airports, 4 −1−18
Hold, For Release, 5 −2−4
Holding, 5 −3−8
Holding Position Markings, 2 −3−1, 2−3−12
for Instrument Landing Systems, 2 −3−12
for Intersecting Taxiways , 2 −3−12
Holding Position Signs, Surface Painted, 2 −3−13
Hypoxia, 8 −1−3I
Icing Terms, 7 −1−43
IFR, 4−4−4
Operations, To High Altitude Destinations, 5 −1−27
Procedures, Use When Operating VFR, 5 −1−2
IFR
Approaches, 4 −1−6
Military Training Routes, 3 −5−1
Separation Standards, 4 −4−7
ILS. See Instrument Landing System
In−Runway Lighting, 2 −1−6
Taxiway Centerline Lead −off Lights, 2 −1−6
Taxiway Centerline Lead −On Lights, 2 −1−6
Touchdown Zone Lighting, 2 −1−6
Incident, Aircraft, Reporting, 7 −6−1
Inertial Navigation System, 1 −1−16
Inertial Reference Unit (IRU), 1 −1−16, 5−1−12
Initial Contact, 4 −2−1
INS. See Internal Navigation System
Instrument Departure Procedures (DP), 5 −2−6
Instrument Landing System, 1 −1−8
Category, 1 −1−12
Compass Locator, 1 −1−11
Course, Distortion, 1 −1−12
Distance Measuring Equipment, 1 −1−10
Frequency, 1 −1−11
Glide Path, 1 −1−10
Glide Slope, 1 −1−10
Critical Area, 1 −1−12
Holding Position Markings, 2 −3−12
Inoperative Components, 1 −1−12
Localizer, 1 −1−9
Critical Area, 1 −1−12
Locators, Compass, 1 −1−8
Marker Beacon, 1 −1−10
Minimums, 1 −1−12
Instrument Meteorological Conditions (IMC), 5 −2−6
Integrated Terminal Weather System, 4 −3−12
Intercept, 6 −2−1
Interception
Procedures, 5 −6−8
Signals, 5 −6−11
Interchange Aircraft, 4 −2−4
International Flight Plan, IFR, Domestic, International,
5−1−17
10/12/17 AIM
Index I−7[References are to page numbers]
International Flight Plan (FAA Form 7233 −4)− IFR
Flights (For Domestic or International Flights),
5−1−17
Intersection Takeof fs, 4−3−15
IR. See IFR Military Training Routes
IRU. See Inertial Reference Unit
ITWS. See Integrated Terminal Weather System
K
K−9 Explosives Detection Team, 6 −2−3
L
LAHSO. See Land and Hold Short Operations
Land and Hold Short Lights, 2 −1−6
Land and Hold Short Operations (LAHSO), 4 −3−15
Landing
Minimums, 5 −4−53
Priority, 5 −4−64
Laser Operations, 7 −5−10
Law Enforcement Operations
Civil, 5−6−10
Military, 5 −6−10
LDA. See Localizer −Type Directional Aid
Leased Aircraft, 4 −2−4
Lifeguard, 4 −2−4
Light Signals, Traffic Control, 4 −3−18
Lighting
Aeronautical Light Beacons, 2 −2−1
Aids
Airport, 2 −1−1
Approach Light Systems, 2 −1−1
Control of Lighting Systems, 2 −1−11
In−Runway Lighting, 2 −1−6
Pilot Control of Airport Lighting, 2 −1−11
Runway End Identifier Lights, 2 −1−6
Taxiway Lights, 2 −1−15
Airport/Heliport Beacons, 2 −1−14
Airport, Radio Control, 4 −1−6
Code Beacon, 2 −2−1
Course, 2 −2−1
Navigation, 2 −2−1
Obstruction, 2 −2−1
Line Up and Wait , 5 −2−2LLWAS. See Low Level Wind Shear Alert System
Local Airport Advisory (LAA), 3 −5−1, 4−1−4
Local Flow Traffic Management Program, 5 −4−3
Localizer −Type Directional Aid, 1 −1−9
Locator, Compass, 1 −1−11
Long Range Navigation, 1 −1−16
LORAN. See Long Range Navigation
Low Approach, 4 −3−18
Low Level Wind Shear Alert System (LLWAS),
4−3−12, 7−1−50
Low Level Wind Shear/Microburst Detection Systems,
4−3−12
LUAW. See Line Up and Wait
M
MAYDAY, 6 −3−1
Medical
Carbon Monoxide Poisoning, 8 −1−5
Decompression Sickness, 8 −1−4
Facts, Pilots, 8 −1−1
Flight, Ear Block, 8 −1−4
Illness, 8−1−1
Medication, 8 −1−1
Sinus Block, 8 −1−4
Meteorology, 7 −1−1
ATC InFlight Weather Avoidance, 7 −1−36
Automated Surface Observing System, 7 −1−27
Categorical Outlooks, 7 −1−16
Clear Air Turbulence, 7 −1−46
Cloud Heights, Reporting, 7 −1−40
Drizzle, Intensity, 7 −1−41
FAA Weather Services, 7 −1−2
ICAO, Weather Formats, 7 −1−62
Icing, Airframe, 7 −1−42
Inflight Aviation Weather Advisories, 7 −1−9
Inflight Weather Broadcasts, 7 −1−17
Microbursts, 7 −1−46
National Weather Service, Aviation Weather Service,
7−1−1
Pilot Weather Reports, 7 −1−41
Precipitation, Intensity, 7 −1−40
Preflight Briefing, 7 −1−7
Runway Visual Range, 7 −1−38
Telephone Information Briefing Service, 7 −1−17
Thunderstorms, 7 −1−57
10/12/17 AIM
Index I−8[References are to page numbers]
Flying, 7−1−58
Transcribed Weather Broadcast, 7 −1−17
Turbulence, 7 −1−45
Visibility, Reporting, 7 −1−40
Weather, Radar Services, 7 −1−32
Weather Observing Programs, 7 −1−24
Wind Shear, 7 −1−46
Military NOT AMs, 5−1−3
Military Operations Areas, 3 −4−2
Military Training Routes, 3 −5−1
IFR, 3−5−1
VFR, 3−5−1
Minimum, Fuel Advisory, 5 −5−7
Minimum Safe Altitudes, 5 −4−9
Minimum Turning Altitude (MTA), 5 −3−8
Minimum Vectoring Altitudes, 5 −4−17
Minimums
Approach, 5 −4−53
Instrument Landing Systems, 1 −1−12
Landing, 5 −4−53
Missed Approach, 5 −4−56
MOA. See Military Operations Areas
Mode C, 4 −1−16
Mountain Flying, 7 −5−3
Mountain Wave, 7 −5−4
Mountainous Areas, 5 −6−13
MSA. See Minimum Safe Altitudes
MTA. See Minimum Turning Altitude (MTA)
Multicom, 4 −1−6
MVA. See Minimum Vectoring Altitudes
N
National Forests, 7 −4−1
National Geospatial −Intelligence Agency (NGA),
5−4−7
National Parks, 7 −4−1
National Refuges, 7 −4−1
National Security, 5 −6−1
ADIZ, 5−6−1
ADIZ Requirements, 5 −6−2Civil Aircraft Operations, 5 −6−3
Defense Area, 5 −6−1
Requirements, 5 −6−1
Territorial Airspace, 5 −6−1
National Security Areas, 3 −4−2
NAVAID
Identifier Removal During Maintenance, 1 −1−15
Maintenance, 1 −1−15
Performance, User Report, 1 −1−15
Service Volumes, 1 −1−5
with Voice, 1 −1−15
Navigation, Aids, 1 −1−1
Nondirectional Radio Beacon, 1 −1−1
Radio, VHF Omni −directional Range, 1 −1−1
Navigation Reference System (NRS), 5 −1−15
Navigation Specifications (Nav Specs), 1 −2−4
Navigational
Aids, Radio
Distance Measuring Equipment, 1 −1−5
Doppler Radar, 1 −1−16
Identifier Removal During Maintenance, 1 −1−15
Instrument Landing System, 1 −1−8
Localizer −Type Directional Aid, 1 −1−9
Long Range Navigation, 1 −1−16
Navaid Service Volumes, 1 −1−5
NAVAIDs with Voice, 1 −1−15
Performance, User Report, 1 −1−15
Simplified Directional Facility, 1 −1−13
Tactical Air Navigation, 1 −1−4
VHF Omni −directional Range/Tactical Air
Navigation, 1 −1−4
Inertial Navigation System, 1 −1−16
NDB. See Nondirectional Radio Beacon
Near Midair Collision, 7 −6−2
NGA. See National Geospatial −Intelligence Agency
NMAC. See Near Midair Collision
Nondirectional Radio Beacon, 1 −1−1
Nonmovement Area Boundary Markings, 2 −3−18
NOTAM. See Notice to Airmen
Notice to Airmen, 5 −1−2
FDC NOTAM, 5 −1−3
NOTAM Contractions, 5 −1−6
NOTAM D, 5 −1−3
Notice to Airmen System, 5 −1−2
Notices to Airmen Publication, NTAP , 5 −1−3
10/12/17 AIM
Index I−9[References are to page numbers]
O
Obstacle Departure Procedures, 5 −2−6
Obstruction Alert, 4 −1−11
Operation Take −off, 4−1−2
Operational Information System (OIS), 5 −1−10
Option Approach, 4 −3−25
P
P−static, 7−5−9
PAN−PAN, 6−3−1
PAPI. See Precision Approach Path Indicator
PAR. See Precision Approach; Precision Approach
Radar
Parachute Jumps, 3 −2−2, 3−5−5
Performance −Based Navigation (PBN), 1 −2−1
Phonetic Alphabet, 4 −2−5
Pilot
Authority, 6 −1−1
Responsibility, 4 −1−14, 4−4−1, 4−4−4, 5−4−62,
5−5−1, 6−1−1, 7−3−6
Pilot Control of Airport Lighting, 2 −1−11
Pilot Visits to Air Traffic Facilities, 4 −1−1
Pilot Weather Reports, 7 −1−41
Piracy, Air, Emergency, 6 −3−6
PIREPs. See Pilot Weather Reports
Pointer NOT AMs, 5−1−3
Position Reporting, 5 −3−3
Pre−Departure Clearance Procedures, 5 −2−1
Precipitation Static, 7 −5−9
Precision Approach, 5 −4−35
Precision Approach Path Indicator, 2 −1−4
Precision Approach Radar, 4 −5−7
Precision Approach Systems, 1 −1−34
Preflight, Preparation, 5 −1−1
Priority, Landing, 5 −4−64
Procedure Turn, 5 −4−29
Limitations, 5 −4−32
ProceduresArrival, 5 −4−1
En Route, 5 −3−1
Instrument Approach, 5 −4−27
Interception, 5 −6−8
Prohibited Areas, 3 −4−1
Publications, Aeronautical, 9 −1−1
Pulsating Visual Approach Slope Indicator, 2 −1−5
R
Radar
Air Traffic Control Radar Beacon System, 4 −5−2
Airport Route Surveillance Radar, 4 −5−7
Airport Surveillance Radar, 4 −5−7
Approach Control, 5 −4−3
Approaches, 5 −4−35
Capabilities, 4 −5−1
Doppler, 1 −1−16
Limitations, 4 −5−1
Monitoring of Instrument Approaches, 5 −4−36
Precision Approach, 4 −5−7
Precision Approach Radar, 4 −5−7
Surveillance, 4 −5−7
Vector, 5−5−3
Radar Assistance to VFR Aircraft, 4 −1−11
Radar Beacon, Phraseology, 4 −1−17
Radar Sequencing and Separation, VFR Aircraft,
TRSA, 4−1−13
Radar Traffic Information Service, 4 −1−9
Radio, Communications, 4 −2−1
Altitudes, 4 −2−6
Contact Procedures, 4 −2−1
Directions, 4 −2−6
Inoperative Transmitter, 4 −2−7
Phonetic Alphabet, 4 −2−5
Receiver Inoperative, 4 −2−7
Speeds, 4 −2−6
Student Pilots, 4 −2−4
Technique, 4 −2−1
Time, 4−2−6
Transmitter and Receiver Inoperative, 4 −2−7
VFR Flights, 4 −2−8
RCLS. See Runway Centerline Lighting
Receiver, VOR, Check, 1 −1−3
REIL. See Runway End Identifier Lights
REL. See Runway Entrance Lights
Release Time, 5 −2−4
10/12/17 AIM
Index I−10[References are to page numbers]
Remote Airport Advisory (RAA), 3 −5−1
Remote Airport Information Service (RAIS), 3 −5−1,
4−1−4
Required Navigation Performance (RNP), 5 −4−23
Required Navigation Performance (RNP) Operations,
5−1−31, 5−5−7
Rescue Coordination Center
Air Force, 6 −2−5
Alaska, 6−2−5
Coast Guard, 6 −2−4
Joint Rescue, Hawaii, 6 −2−5
Reservations, Airport, 4 −1−18
Responsibility
Controller, 5 −3−8, 5−4−62, 5−5−1
Pilot, 4−1−14, 4−4−1, 4−4−4, 5−4−62, 5−5−1, 6−1−1,
7−3−6
Restricted Areas, 3 −4−1
Restrictions
Departure, 5 −2−4
Flight, Temporary, 3 −5−2
RIL. See Runway Intersection Lights (RIL)
RNAV. See Area Navigation
Route
Coded Departure Route, 4 −4−3
Course Changes, 5 −3−7
Route System, 5 −3−5
Runway
Aiming Point Markings, 2 −3−2
Centerline Markings, 2 −3−2
Closed
Lighting, 2 −3−18
Marking, 2 −3−18
Condition Reports, 4 −3−13
Demarcation Bar, 2 −3−4
Designators, 2 −3−2
Holding Position Markings, 2 −3−12
Markings, 2 −3−1
Separation, 4 −4−10
Shoulder Markings, 2 −3−3
Side Stripe Markings, 2 −3−3
Signs, Distance Remaining, 2 −3−29
Threshold Bar, 2 −3−4
Threshold Markings, 2 −3−3
Touchdown Zone Markers, 2 −3−2
Runway
Edge Light Systems, 2 −1−6
End Identifier Lights, 2 −1−6Entrance Lights, 2 −1−7
Centerline Lighting System, 2 −1−6
Status Light (RWSL) System, 2 −1−7, 2−1−8
Runway Intersection Lights (RIL), 2 −1−9
RWSL System, Runway Status Light (RWSL) System.
See Runway Status Light (RWSL) System
Runway, Visual Range, 7 −1−38
Runways, Use, 4 −3−7
RVR. See Runway Visual Range
S
Safety
Alert, 5−5−3
Alerts, 3−2−1
Aircraft Conflict, 3 −2−1
Mode C Intruder, 3 −2−1
Terrain/Obstruction, 3 −2−1
Aviation, Reporting, 7 −6−1
Seaplane, 7 −5−6
Safety Alert, 4 −1−10
Aircraft Conflict Alert, 4 −1−11
Obstruction Alert, 4 −1−11
Terrain Alert, 4 −1−11
SAR. See Search and Rescue
SCAT−I DGPS. See Special Category I Differential
GPS
Scuba Diving, Decompression Sickness, 8 −1−4
SDF. See Simplified Directional Facility
Seaplane, Safety, 7 −5−6
Search and Rescue, 6 −2−1, 6−2−4
Security Identification Display Area, 2 −3−31
See and Avoid, 5 −5−4
Separation
IFR, Standards, 4 −4−7
Runway, 4 −4−10
Visual, 4−4−10, 5−5−6
Wake Turbulence, 7 −3−7
Sequenced flashing lights (SFL), 2 −1−11
SFL. See Sequenced flashing lights
SIDA. See Security Identifications Display Area
Side−Step Maneuver, 5 −4−53
Signs
Airport, 2 −3−1
Half−Way, 7−5−5
10/12/17 AIM
Index I−11[References are to page numbers]
Simplified Directional Facility, 1 −1−13
Sinus Block, 8 −1−4
Special Air Traffic Rules (SATR), 3 −5−9
Special Category I Differential GPS (SCAT −I DGPS),
1−1−35
Special Flight Rules Area (SFRA), 3 −5−9
Special Instrument Approach Procedures, 1 −1−34,
5−4−28
Special Traffic Management Programs, 4 −1−18
Special Use Airspace, 3 −4−1
Alert Areas, 3 −4−2
Controlled Firing Areas, 3 −4−2
Military Operations Areas, 3 −4−2
Prohibited Areas, 3 −4−1
Restricted Areas, 3 −4−1
Warning Areas, 3 −4−1
Special Use Airspace (SUA) NOTAMs, 5 −1−3
Special VFR Clearances, 4 −4−3
Speed, Adjustments, 4 −4−7, 5−5−4
Spoofing, 1 −2−8
Standard Instrument Departures, 5 −2−6
Standard Terminal Arrival, 5 −4−1
STAR. See Standard Terminal Arrival
Surface Painted Holding Position Signs, 2 −3−13
Surveillance Approach, 5 −4−35
Surveillance Radar, 4 −5−7
Surveillance Systems, 4 −5−1
T
TACAN. See Tactical Air Navigation
Tactical Air Navigation, 1 −1−4
TAF. See Aerodrome Forecast
Takeoff Hold Lights (THL), 2 −1−8
Takeoffs, Intersection, 4 −3−15
Taxi
Clearance, 5 −2−2
During Low Visibility, 4 −3−23
Taxiway
Centerline Markings, 2 −3−7
Closed
Lighting, 2 −3−18
Marking, 2 −3−18Edge Markings, 2 −3−7
Geographic Position Markings, 2 −3−10
Holding Position Markings, 2 −3−12
Markings, 2 −3−1, 2−3−7
Shoulder Markings, 2 −3−7
Surface Painted Direction Signs, 2 −3−10
Surface Painted Location Signs, 2 −3−10
Taxiway Centerline Lead −Off Lights, 2 −1−6
Taxiway Lights, 2 −1−15
Centerline, 2 −1−15
Clearance Bar, 2 −1−15
Edge, 2−1−15
Runway Guard, 2 −1−15
Stop Bar, 2 −1−15
TCAS. See Traffic Alert and Collision Avoidance
System
TDWR. See Terminal Doppler Weather Radar
TDZL. See Touchdown Zone Lights
TEC. See Tower En Route Control
Telephone Information Briefing Service, 7 −1−17
Temporary Flight Restrictions, 3 −5−2
Terminal Arrival Area (TAA), 5−4−9
Terminal Doppler Weather Radar (TDWR), 4 −3−12,
7−1−51
Terminal Radar Service Areas, 3 −5−9
Terminal Radar Services for VFR Aircraft, 4 −1−12
Terminal Weather Information For Pilots System
(TWIP), 7 −1−56
Terrain Alert, 4 −1−11
THL. See Takeoff Hold Lights
TIBS. See Telephone Information Briefing Service
Time
Clearance V oid, 5−2−4
Release, 5 −2−4
TIS. See Traffic Information Service
TIS−B. See Traffic Information Service −Broadcast
TLS. See Transponder Landing System
Touchdown Zone Lights (TDZL), 2 −1−6
Tower, Antenna, 7 −5−1
Tower En Route Control, 4 −1−14
Traffic
Advisories, 5 −5−5
Local Flow Traffic Management Program, 5 −4−3
10/12/17 AIM
Index I−12[References are to page numbers]
Traffic Advisory Practices, Airports Without Operating
Control T owers, 4−1−2
Traffic Alert and Collision Avoidance System, 4 −4−11
Traffic Control Light Signals, 4 −3−18
Traffic Information Service, 4 −5−8
Traffic Information Service (TIS), 4 −4−12
Traffic Information Service −Broadcast , 4 −5−18
Traffic Patterns, 4 −3−2
Transcribed Weather Broadcast, 7 −1−17
Transponder Landing System (TLS), 1 −1−35
Transponder Operation, 4 −1−15
Automatic Altitude Reporting, 4 −1−16
Code Changes, 4 −1−16
Emergency, 6 −2−1
Ident Feature, 4 −1−16
Mode C, 4 −1−16
Under Visual Flight Rules, 4 −1−17
VFR, 4−1−17
Tri−Color Visual Approach Slope Indicator, 2 −1−4
TRSA. See Terminal Radar Service Areas
Turbulence, Wake, 7 −3−1
Air Traffic Separation, 7 −3−7
Helicopters, 7 −3−6
Pilot Responsibility, 7 −3−6
Vortex Behavior, 7 −3−2
Vortex Generation, 7 −3−1
Vortex Strength, 7 −3−1
TWEB. See Transcribed Weather Broadcast
TWIP. See Terminal Weather Information For Pilots
System
U
Ultralight Vehicles, 3 −2−2
Unicom, 4 −1−6
Unidentified Flying Object (UFO) Reports, 7 −6−3
Unmanned Aircraft, 7 −5−2
Urgency, 6 −3−1V
VASI. See Visual Approach Slope Indicator
VDP . See Visual Descent Points
Vector, Radar, 5 −5−3
Vehicle Roadway Markings, 2 −3−16
Vertical Navigation, 5 −1−12
VFR Corridors, 3 −5−7
VFR Flights in Terminal Areas, 4 −3−20
VFR Flyways, 3 −5−5
VFR Military Training Routes, 3 −5−1
VFR Transition Routes, 3 −5−7
VFR−on−Top, 5−5−6
VHF Omni −directional Range, 1 −1−1
Minimum Operational Network (MON), 1 −1−2
VHF Omni −directional Range/Tactical Air Navigation,
1−1−4
Visual
Approach, 5 −4−62, 5−5−5
Clearing Procedures, 4 −4−11
Glideslope Indicators, 2 −1−1
Separation, 4 −4−10, 5−5−6
Visual Approach Slope Indicator, 2 −1−1
Visual Climb Over Airport, 5 −2−8
Visual Descent Point, 5 −4−19
Visual Meteorological Conditions (VMC), 5 −2−6
VNA V. See Vertical Navigation
VOCA. See Visual Climb Over Airport
Void Times, Clearance, 5 −2−4
Volcanic, Ash, 7 −5−7
Volcanic Activity Reporting, Forms. See Appendix 2
VOR See also VHF Omni −directional Range
Receiver Check, 1 −1−3
VOR Receiver Checkpoint Markings, 2 −3−16
VORTAC. See VHF Omni −directional Range/Tactical
Air Navigation
VR. See VFR Military Training Routes
10/12/17 AIM
Index I−13[References are to page numbers]
W
Waivers, 4 −1−20
Wake, Turbulence, 7 −3−1
Warning Areas, 3 −4−1
WeatherDeviations in Oceanic Controlled Airspace, 7 −1−37
ICAO, Weather Formats, 7 −1−62
Weather Reconnaissance Area (WRA), 3 −5−9
Weather System Processor (WSP), 4 −1−20, 4−3−12,
7−1−52
WSP. See Weather System Processor
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