AC 91-85B - RVSM Operations

U

.S. Department

of Transportation

Federal Aviation

Administration Advisory

Circular

Subject: Authorization of Aircraft and

Operators for Flight in Reduced

Vertical Separation Minimum

(RVSM) Airspace Date: 1 /29/19 AC No: 91-85B

Initiated by: AFS- 400 Change:

This advisory circular ( AC) provides airworthiness and operational authorization guidance

material for operators, pilots, certificate holders, and/or program managers conducting Title 14

of the Code of Federal Regulations (14 CFR) part 91, §§ 91.180 and 91.706 Reduced Vertical

Separation Minimum (RVSM) operations . RVSM airspace is any airspace or route between

flight level (FL) 290 and FL 410 inclusive where aircraft are separated vertically by 1,000 feet.

This AC has been updated to include guidance on eligibility and compliance for §§ 91.180 and 91.706 RVSM operations when operators seek RVSM authorization under the provisions of

the new Part 91 Appendix G

, Section 9, Aircraft Equipped with A utomatic Dependent

Surveillance – Broadcast Out .

The Federal Aviation Administration ( FAA ) intends to transition current authorizations, issued

under part 91 appendix G, s ection 3 , to monitor operations under the provisions of part 91

appendix G, s ection 9 . This action reduces the operator and FAA administrative burdens

associated with maintaining the part 91 appendix G, section 3 authorizations.

R

obert C. Carty

Deputy Executive Director, Flight Standards Service

1/29/19 AC 91 -85B

CONTENTS

Paragraph Page

Chapter 1. General ...................................................................................................................... 1-1

1.1 Purpose of This Advisory Circular (AC) ...................................................................... 1-1

1.2 Audience ....................................................................................................................... 1-1

1.3 Where You Can Find This AC ...................................................................................... 1-1

1.4 What This AC Cancels .................................................................................................. 1-1

1.5 AC Format .................................................................................................................... 1-1

1.6 Airworthin ess ................................................................................................................ 1-1

1.7 Related Regulations ...................................................................................................... 1-2

1.8 Related Reading Materia l ............................................................................................. 1-2

1.9 AC Feedback Form ....................................................................................................... 1-2

Chapter 2. Aircraft Eligibility ..................................................................................................... 2-1

2.1 Introduction ................................................................................................................... 2-1

2.2 Aircraft Eligibility ......................................................................................................... 2-1

2.3 Configuration Control ................................................................................................... 2-1

2.4 Maintenance .................................................................................................................. 2-1

2.5 RVSM Performance ...................................................................................................... 2-1

Chapter 3. Knowledge and Training ........................................................................................... 3-1

3.1 Pilot Knowledge ............................................................................................................ 3-1

3.2 Pilot Knowledge Subject Areas .................................................................................... 3-1

3.3 Pilot Currency ............................................................................................................... 3-2

Chapter 4. Authorizations for Opera tors of RVSM Aircraft Equipped W ith a Qualified

ADS -B OUT System .................................................................................................. 4-1

4.1 Introduction ................................................................................................................... 4-1

4.2 Flight Planning .............................................................................................................. 4-1

4.3 Altitude -Keeping Performance Monitoring for RVSM Aircraft Equipped With

ADS -B OUT ................................................................................................................. 4-1

4.4 RVSM Altitude -Keeping Performance Website ........................................................... 4-3

ii

1/29/19 AC 91 -85B

Chapter 5. Operators Applying for RVSM OpSpec s, MS pecs, or LOAs ................................... 5-1

5.1 Introduction ................................................................................................................... 5-1

5.2 RVSM Authorization Elements Background ................................................................ 5-1

5.3 Authorization Matrix .................................................................................................... 5-1

5.4 Applying for an RVSM OpSpec, MSpec, or LOA ....................................................... 5-3

5.5 Providing Evidence for RVSM Authorization .............................................................. 5-3

5.6 RVSM Applicant .......................................................................................................... 5-4

5.7 Responsible Person ....................................................................................................... 5-5

5.8 Considerations When Applying for an RVSM OpSpec, MSpec, or LOA .................... 5-6

5.9 Applicable Forms for t he RVSM Authorization Documents ....................................... 5-9

5.10 Conditions Requiring th e Removal of an Authorization ........................................... 5-10

Appendix A. RVSM Airworthiness Certification ...................................................................... A-1

Appendix B. Training Programs and Operating Practices and P rocedures ................................B -1

Appendix C. Operations Outside of U.S.- Controlled Airspace ..................................................C -1

Appendix D. Severe Turb ulence and M ountain Wave Activity ................................................ D-1

Appendix E. RVSM Altitude -Keeping P erformance Monitoring When Operating With

an RVSM OpSpec, MS pec, or L OA ..................................................................... E-1

Appendix F. Decision Matrix When Applying for an RVSM OpSpec, MSpec, or LOA .......... F-1

iii

1/29/19 AC 91 -85B

List of Figures

Figure A -1. Example of Air Data System/Autopilot Configuration ....................................... A-13

Figure A -2. Single Air -Data Computer Configuration for Autopilot Input ............................ A-14

Figure A -3. Altimetry System Error and Its Components ....................................................... A-18

Figure A -4. Static Source Error/Static Source Error Correction Relationships for

Altimetry System Error Where Static Line, Press ure Measurement, and

Conversion Errors Are Zero ................................................................................. A-22

Figur e A-5. Process for Showing Initial and Continued Complia nce of Airframe Static

Pressure System ................................................................................................... A-27

Figure A -6. Compliance Demonstration Ground- To-Flight Test Correlation

Process Example .................................................................................................. A-27

Figure A-7. Process for Showing Initial and Continued Complia nce of Airframe Static

Pressure Systems for In -Service and New Model Aircraft .................................. A-28

Figure B -1. Flight Level Orientation Scheme ........................................................................... B-1

List of Tables

Table A -1. Full RVSM Envelope Boundaries ......................................................................... A-5

Table A -2. Static Source Error ............................................................................................... A-20

Table A -3. Residual Static Source Error (Aircraft w ith Avionic Static Source

Error Correction) .................................................................................................. A-21

Table B -1. RVSM Phraseology ............................................................................................... B-6

Table B -2. Contingency Actions: Weather Encounters and Airc raft System Failures

That Occur After Entry into RVSM Airspace ....................................................... B-7

Table F -1. RVSM Decision Matrix .......................................................................................... F-1

iv

1/29/19 AC 91 -85B

CHAPTER 1. GENERAL

1.1 Purpose of This Advisory Circular (AC). This AC provides airworthiness and

operational authorization guidance material fo r operators, pilots, certificate holders,

and/or program managers conducting Title 14 of the Code of Federal Regulations

(14 CFR ) part 91, §§ 91.180 and 91.706 Reduced Vertical Separation Minimum (RVSM)

operations. RVSM airspace is any airspace or route between flight level (FL) 290 and

FL 410 inclusive where aircraft are separated vertically by 1,000 feet. The term “must” is

used in this AC to indicate a mandatory requirement driven by regulation or required for a system to operate properly. The term “should” is used to indicate a r ecommendation.

The term “operator” refers to the certificate holder, program manager, and operator/company for aircraft used i n RVSM airspace for 14 CFR part s

91, 91 subpart K

(part 91K), 121, 125, and 135 operations.

1.2 Audience. This AC applies to operators, pilots, certificate h olders, and/or program

managers under parts 91, 91K, 121, 125, and 135 conducti ng RVSM operations in the

United States or in oceanic and remote airspace. This AC also applies to U.S. -registered

operators where foreign authority has adopted International Civil Aviation Organization

(ICAO) RVSM operations.

1.3 Where You Can Find This AC. You can find this AC on the Federal Aviation

Administration’s ( FAA ) website at

http://www.faa.gov/reg ulations_policies/advisory_circulars .

1.4 What This AC Cancels. AC 91 -85A, Authorization of Aircraft and Operators for Flight

in Reduced Vertical Separation Minimum (RVSM) Ai rspace, dated July 21, 2016, is

canceled.

1.5 AC Format.

• Chapter 2, Aircraft Eligibility , and Chapter 3 , Knowledge and Training , apply to all

operators, pilots, certificate holders, and/or program managers.

• Chapter 4 , Authorizations for Operators of RVSM Aircraft Equipped with a Qualified

ADS -B OUT System , applies to operators and pilots intending to operate in RVSM

airspace under the provisions of part 91 a ppendix G, section 9.

• Chapter 5 , Operators Applying for RVSM OpSpecs, MSpecs, or LOAs , applies to

operators and pilots of aircraft not equipped with a qualified Automatic Dependent Surveillance- Broadcast ( ADS -B) OUT system or when operating in a country

requiring specific approval. Operators may also obtain this approval if the aircraft is not routinely flown in airspace where the FAA has sufficient ADS -B data to

determine RVSM performance.

1.6 Airworthiness. For RVSM a ircraft a irworthiness requirements , see Appendix A , RVSM

Airworthiness Cert ification .

1/29/19 AC 91 -85B

1.7 Related Regulations. Title 14 CFR:

• Part 91, §§ 91.180 and 91.706, subpart K , and a ppendix G .

• Part 121 .

• Part 125 .

• Part 135 .

1.8 Related Reading Material.

1.8.1 FAA Documents . The following documents are available at

https://www.faa.gov/air_traffic/publications/ :

• Aeronautical Information Manual (AIM).

• Aeronautical Information Publication (AIP).

1.8.2 ICAO Documents :

• ICAO Annex 2, Rules of the Air.

• ICAO Annex 6, Operation of Aircraft, Part I—Internati onal Commercial

Air Transport —Aeroplanes and Part II—International General

Aviation —Aeroplanes.

• ICAO Annex 11, Air Traffic Services.

• ICAO Doc 4444 , Procedures for Air Navigation Services, Air Traffic Management.

• ICAO Doc 7030 , Regi onal Supplementary Procedures.

• ICAO Doc 9574 , Manual on a 300 m (1,000 ft) Vertica l Separation Minimum

Between FL 290 and FL 410 Inclusive.

1.9 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of

this AC. Note any deficiencies found, clarifications needed, or suggested improvements

regarding the contents of this AC on the Feedback Form.

1/29/19 AC 91 -85B

CHAPTER 2. AIRCRAFT ELIGIBILITY

2.1 Introduction. This chapter provides guidance on how operators can determine if their

aircraft is compliant and eligible for operations in RVSM airspace.

2.2 Aircraft Eligibility. An aircraft is an “RVSM -Compliant Aircraft” when :

1. The aircraft design ensures the aircraft will meet RVSM performance

requirements ; and

2. The aircraft has been properly maintained on an ongoing ba sis to conduct such

operations.

2.2.1 Aircraft may be produced RVSM -compliant or brought into compliance through the

application of appropriate Service Bulletins (SB), Service Letters (SL), Engineering

Change Orders (EO), or Supplemental Type Certificates (STC). For airworthiness

guidance, see Appendix A , RVSM Airworthiness Certification .

2.2.2 To determine eligibility for RVSM operations , the limitations section of the Airplane

Flight Manual (AFM) or AFM Supplement (AFMS) should indicate the aircraft has been

determined to be capable of meeting the RVSM performance requirements of 14 CFR

part 91 a ppendix G.

Note: For operators and pilots authorized under part 91 appendix G , section 9 , the

aircraft may have qualified as Group or Non -Group aircraft described in

Appendix A.

2.3 Configuration Control. Operators must maintain their aircraft altimetry and

altitude -keeping configuration which has been sho wn to provide the required RVSM

performance.

2.4 Maintenance. The operator is responsible for maintenance of the systems affecting

RVSM performance on the aircraft. The operator must ensure that it complies with the

appropriate i nstructions for c ontinued a irworthiness (ICA).

2.4.1 System Alteration or Design Modifications (Including Software Updates) . Operat ors

must evaluate alterations to the aircraft and identify any changes that impact altitude -keeping ability. The operator should establish that the alteration did not affect the

RVSM system , or if it was affected, affirm the compliance to meet associated

performance standards. When modifying an aircraft based on an approved design change ,

the owner of the approved design change should identify any effect on RVSM performance. Operators must determine aircraft RVSM eligi bility after each alteration or

modific ation.

2.5 RVSM Performance. Altitude -keeping performance of airplanes is a key element in

ensuring safe operations in RVSM airspace. RVSM is a “performance- based” operation

requiring monitoring on an ongoing basis.

1/29/19 AC 91 -85B

2.5.1 Altitude -Keeping Performance Monitoring . RVSM aircraft must participate in

altitude -keeping performance monitoring programs to ensure safe and efficient operations

in RVSM airspace.

2.5.1.1 Operators and pilots conducting RVSM operations under the provisions of

part 91 appendix G, s ection 9 must ensure t heir aircraft meet the RVSM

altitude -keeping performance monitoring requirements as described in

Chapter 4, paragraph 4.3 . Under these provisions, airc raft with qualified

ADS -B OUT systems will be monitored during normal operations whenever

operating at RVSM altitudes where sufficient ADS -B data is available to the

FAA to determine RVSM performance. All aircraft in an operator’s fleet must

have been moni tored within the previous 24 months and found to be in

compliance with the performance requirement specified in part 91 appendix G, section 9(b).

2.5.1.2 Operators conducting RVSM operations under the provision of part 91 appendix G, s ection 3 must meet the RVSM M inimum M onitoring

Requirements (MMR) and have their aircraft monitored as specified in

Appendix E

, RVSM Altitude -Keeping Perform ance Monitoring When

Operating W ith an R VSM OpSpec, MSpec, or LOA .

1/29/19 AC 91 -85B

CHAPTER 3. KNOWLEDGE AND TRAINI NG

3.1 Pilot Knowledge. All pilots conducting operation s in RVSM airspace must be proficient

with the procedures and operations associated with RVSM.

3.1.1 Title 14 CFR Parts 91K , 121, 125, and 135 Operator Training . Part s 91K , 121, 125 ,

and 135 operators should have a training program addressing the operational practices,

procedures , and training items related to RVSM (e.g., initial, upgrade, or recurrent

training for pilots, operational control personnel, and maintenance personnel).

Note: A separate training program is not required if RVSM training is integrated

into the operator’s existing training program.

3.2 Pilot Knowledge Subject Areas. The following subjects should be addressed during the

initial introduction of a pilot to RVSM operations (see also Appendi x B, Training

Programs and Ope rating Practices and Procedures; Appendix C, Operations Outside of

U.S.-Controlled Airspace ; and Appendix D, Seve re Turbulence and Mountain Wave

Activity ):

1. Description of RVSM airspace, including Flight Level Allocation

Schemes (FLAS).

2. Flight planning for RVSM aircraft.

3. Preflight procedures.

4. Procedures before RVSM airspace entry.

5. In-flight procedures.

6. RVSM pilot air traffic control (ATC ) phraseology.

7. Contingency procedures after entering RVSM airspace.

8. Postflight procedures.

9. Non-RVSM aircraft.

10. Altitude -keeping performance monitoring.

11. Minimum e quipment l ist (MEL).

12. Traffic Alert and Collision Avoidance System (TCAS) considerations for

RVSM (if TCAS -equipped).

13. RVSM oceanic operations (if applicable).

14. International operations (if applicable).

15. Severe t urbulence and Mountain Wave Activity (MWA) .

1/29/19 AC 91 -85B

Note: For subsequent ground training, only the new, revised, or emphasized items

need be addressed.

3.3 Pilot Currency. Pilot currency programs/training should also include RVSM elements

listed in paragraph 3.2 .

1/29/19 AC 91 -85B

CHAPTER 4. AUTHORIZATIONS FOR O PERATORS OF RVSM AIRCRAFT

EQUIPPED WITH A QUALIFIED ADS -B OUT SYSTEM

4.1 Introduction. This chapter discusses RVSM operations for operators and pilots seeking

to conduct flight in RVSM airspace under the provisions of 14 CFR part 91 appendix G ,

section 9.

4.1.1 Operators and pilots seeking to operate in RVSM airspace under the provisions of part 91

appendix G, s ection 9 are not required to apply for authorizations. The operator or pilot

needs to ensure all applicable requirements in part 91 appendix G to operate in RVSM airspace are met. The operator or pilot should:

1.Determine the aircraft is RVSM -compliant ( see Chapter 2

, Aircraft

Eligibility );

2. Ensure pilots are knowledgeable ( see Chapter 3 , Knowledge and Training);

3.Ensure the aircraft meets RVSM performance and the aircraft has been

height-monitored in accordance with paragraph 4.3 (see paragraph 4.3.5 when

an operator is conducti ng the initial flight in RVSM airspace); and

4. Properly file a flight plan and understand the policies and procedures for the

RVSM airspace in which the aircraft will operate.

4.2 Flight Planning. ATC uses flight planning codes to determine when to assign 1,000 ft

separation in RVSM- designated airspace. See Appendix B , Training Programs and

Operating Practices and Procedures, for proper flight planning procedures.

4.2.1 Non-RVSM Aircraft . If the aircraft is not eligible for RVSM operations or the flightcrew

does not have knowledge of RVSM requirements, policies, and procedures sufficient for the conduct of operations in RVSM airspace, the aircraft is considered a non- RVSM

aircraft.

4.3 Altitude -Keeping Performance Monitoring f or RVSM Aircraft Equipped W ith

ADS -B OUT. The goal of altitude -keeping performance monitoring is to ensure safe and

efficient operations and determine aircraft compliance on an ongoing basis.

4.3.1 Altimetry System Error (ASE). Proper vertical separation in RVSM air space relies on

strict altitude -keeping pe rformance of the aircraft. AS E is the difference between t he

pressure altitude displayed to the flightcrew a nd free stream pressure a ltitude. It is a ke y

component of Total Vertical E rror (TVE). T his di fference i s not seen on the displayed

altitude in the flight deck a nd it is not in the Altitude Reporting Mode of Secondary

Radar ( Mode C) or M ode S elect S econdary R adar w ith Data Link (Mode S) reply from

the aircraft transponder . Therefore, it is invisible to the pilot, to routine ATC , and to

the TCAS.

1/29/19 AC 91 -85B

4.3.2 Aircraft ICA s are designed to keep the ASE to within the limits of the error budget

throughout the flight envelope. Regardless, even with attention to continuing

airworthiness, there are factors that can affect the ASE significantly and can go undetected with out altitu de-keeping performance monitoring.

4.3.3 Aircraft equipped with qualified ADS -B OUT systems will be height- monitored during

normal operations at RVSM altitudes when operating in airspace where sufficient ADS -B

data is available to the FAA to determine RVSM perfo rmance.

4.3.4 For RVSM altitude -keeping performance monitoring purposes , a qualified ADS -B OUT

system is one that meets the performance requirements in part 91, § 91.227

4.3.4.1 ADS -B OUT provides the necessary aircraft information for the FAA to

perform altitude -keeping performance monitoring on a continual basis during

normal RVSM aircraft operations whenever the aircraft is operating at RVSM

altitudes in airspace where sufficient ADS -B data is available to the FAA to

determine RVSM performance. A map of that airspace can be found at

https://www.faa.gov/nextgen/programs/ads b/coverageMap/ .

Note: The FAA may also expand the airspace in which we collect

altitude -keeping performance data via ADS -B through collaboration

with other air navigation service providers (ANSP) .

4.3.4.2 The ADS -B OUT equipment requirement i s necessary for aircraft

altitude -keeping performance monitoring, but not for aircraft altitude -keeping

capability. Accordingly, an aircraft meeting RVSM altitude -keeping

performance specified in part 91 appendix G, s ection 9, and having a current

successful monitoring in accordance with paragraph 4.3.5, is authorized to

operate in RVSM airspace when ADS -B OUT is temporarily inoperable.

Note: This does not relieve the operator of any other requirements

regarding the use of ADS -B for the specific airspace where operations

are intended.

4.3.5 The a ltitude -keeping performance must be monitored as follows:

4.3.5.1 The initial RVSM operation of an aircraft must be in airspace where sufficient ADS -B data will be collected for the FAA to evaluate RVSM performance.

Initial RVSM operation occurs at the first RVS M flight of a new aircraft, the

first RVSM flight after alterations affecting RVSM performance have been performed, or the first RVSM flight of an aircraft returned to RVSM operational status after having been removed for any reason.

1. Operators must ensure co mpliant performance prior to operations

in RVSM airspace out side U.S.- controlled airspace (s ee

paragraph 4.4

). An operator may obtain authorization without first

flying in airspace in which the FAA moni tors ADS -B operations

1/29/19 AC 91 -85B

as described in Chapter 5, Operators Applying for RVSM

OpSpecs, MSpecs, or LOAs .

2. For altitude -keeping performance monitoring purposes, the FAA

tracks aircraft by serial number. Transfer of ow nership or the

registration number of a properly maintained aircraft does not

affect aircraft RVSM status under part 91 appendix G, s ection 9.

4.3.5.2 The aircraft’s altitude -keeping performance must have been monitored within

the previous 24 months in airspace the FAA can monitor the aircraft

ADS -B OUT signal and found to be in RVSM compliance.

4.3.5.3 The aircraft must continue to meet the altitude -keeping performance specified

in part 91 appendix G, s ection 9(b).

4.4 RVSM Altitude -Keeping Performance Website. U.S. -registered operators may obtain

monitoring performance from the FAA altitude -keeping performance website at

https://www.faa.gov/air_traffic/separation_standards/naarmo/ .

4.4.1 If the operator does not meet the monitoring requirements specified in paragr aph 4.3.5 ,

the operator must file as non- RVSM aircraft until the issue is resolved. Common

resolution actions include:

1. If a specific oper ational issue is identified as the cause of the unsatisfactory

performance, conduct appropriate knowledge training and/or modification of training programs, as applicable, and obtain concurrence from the FAA Flight

Standards Service prior to resuming RVSM operations;

2. If the unsatisfactory performance is attributed to an aircraft component failure, RVSM operation may be resumed after repair and return to service of the aircraft. The operator must comply with the provisions of paragraph 4.3.5 (initial RVSM op eration flight); or

3. If the cause of the unsatisfactory performance cannot be attributed to an operational issue or aircraft component failure, an airworthiness evaluation of the aircraft must take place with attention to conformity of design and alteration s/modifications, with discrepancies noted and repaired. Prior to

resuming RVSM operations , a monitoring flight of the aircraft in normal

operating configuration must be performed to ensure acceptable performance and obtain concurrence from the FAA Flight S tandards Service prior to

resuming RVSM operations.

4.4.2 Operators of airplanes that do not routinely operate in airspace where sufficient ADS -B

data is available to the FAA to determine RVSM performance, or when a foreign country requires a specific approval, may seek an RVSM auth orization via operations

specification ( OpSpec ), management specification ( MSpec) , or letter of authorization

(LOA ) under the provisions of part 91 appendix G, s ection 3. (See Ch apter 5.)

1/29/19 AC 91 -85B

CHAPTER 5. OPERATORS APPLYING F OR RVSM OPSPECS , MSPEC S, OR LOA s

5.1 Introduction. This chapter provides guidance on applying for RVSM authorization

under the provisions of 14 CFR part 91 appendix G , section 3. Operators must obtain an

operations specification ( OpSpec ), management specification ( MSpec ), or letter of

authorization ( LOA ) for RVSM operations to operate an airc raft that is not Automatic

Dependent Surveillance- Broadcast ( ADS -B) OUT-equipped, or when operating in a

country requiring specific approval. Operators may also obtain this approval if the

aircraft is not routinely flown in airspace where the FAA has sufficient ADS -B data to

determine RVSM performance.

5.1.1 Definitions . For the purposes of efficiency and consistency, when the various capitalized

terms below are used in this AC, then they have the following meanings :

1. Operator. The person who should be the R VSM authorization applicant and

holder. See paragraph 5.6 for a detailed discussion on who is and is not the

correct person to be designated as an operator for the purposes of holding an RVSM authorization.

2. RVSM -Compliant Aircraft. An aircraft the FAA has found to comply with

the requirements of part 91 appendix G, for the purposes of conducting

RVSM operations. ( See Chapter 2 , Aircraft Eligibility .)

3. RVSM -Knowledgeable Pilots. Pilots who have been trained according to

RVSM operating policies and/or procedures for pilots (and, if applicable, dispatchers) with sufficient knowledge for the conduct of operations in RVSM airspace. ( See Chapter 3

, Knowledge and Training.)

4. RVSM -Point of Contact (POC). A pers on an operator can designate in

addition to the RVSM -Responsible Person to act as a contact person who has

actual day -to-day knowledge of the RVSM -Compliant Aircraft operations and

RVSM airworthiness statu s and who the FAA may contact to gather such

information when the need arises.

5. RVSM -Responsible Person. A person(s) designated by the operator who has

the legal authority to sign the RVSM authorization on behalf of the operator and who has adequate knowledge of R VSM requirements, policies, and

procedures. (See paragraph 5.7

.)

5.2 RVSM Authorization Elements Background. The RVSM authorization process

recognizes two key elements of any RVSM authorization : an RVSM -Compliant Aircraft

(see Chapter 2) and properly trained pilots who have met applicable

RVSM -Knowledgeable Pilots requirements ( see Chapter 3). Under the provisions of

part 91 a ppendix G , section 3, an operator must comply with both of these elements to be

authorized to operate in RVSM airspace.

5.3 Authorization Matrix. The RVSM Authorization Matrix (or simply the “Matrix”) is a

tool created to assist operators and the FAA in determining the typical documentation needed for application and which RVSM authorization approval action the applicant

1/29/19 AC 91 -85B

is seeking. (See Appendix F , Decision Matrix When Applying for an RVSM OpSpec,

MSpec, or LOA .)

5.3.1 Authorization Group I . Authorization Group I applies to applicants seeking only

administrative c hanges to an existing authorization. The following changes are

considered to be administrative in nature only when all other existing RVSM elements

are not changed:

1. Change in the primary business address of an RVSM -Compliant Aircraft

and/or RVSM authorizat ion holder.

2. Change in an existing RVSM operator’s designated Responsible Pers on (or

RVSM -Authorized Representative or RVSM -POC).

3. Change in the registration markings of an RVSM -Compliant Aircraft being

operated by an existing RVSM authorization holder.

4. Remo val of an RVSM -Compliant Aircraft from an existing RVSM

authorization having multiple RVSM -Compliant Aircraft listed.

5.3.2 Authorization Group II . Authorization Group II applies to applicants seeking new RVSM

authorizations based on one or more existing approve d RVSM elements. This G roup will

normally apply to a new or proposed RVSM operator seeking the issuance of an RVSM authorization for an aircraft already an RVSM -Compliant Aircraft or where the new

RVSM operator will be utilizing previously accepted RVSM -Knowledgeable Pilots

requirements with respect to its operations of that specific aircraft. Examples given in the

Matrix include:

1. There is a change in the legal status or identity of the business entity that is the approved RVSM operator, but the Responsible Person, RVSM -Authorized

Representative, and/or RVSM -POC and each of the approved RVSM

Authorization Elements are remaining the same.

2. A new proposed RVSM operator will be using an existing RVSM -Compliant

Aircraft or previously accepted RVSM -Knowledgeable P ilots.

3. An existing or new ly proposed approved RVSM operator seeks an RVSM

authorization and will be utilizing one or more existing approved RVSM Authorization Elements.

5.3.3 Authorization Group III . Authorization Group III applies to applicants for new RVSM

authorizations not based on any existing RVSM Authorization Elements. If neither

Authorization Group I nor II apply, the applicant should submit sufficient evidence to show its ability to comply with each of the RVSM Authorization Elements.

5.3.4 Additional Issues When Using the Matrix . The FAA has created inspector guidance to

allow for the most efficient processing of an RVSM authorization without sacrificing operational safety. While a safety inspector may rely on that guidance in issuing new or amended RVSM auth orizations, applicants should understand each appropriate Flight

Standards office, principal operations inspector (POI), principal avionics inspector (PAI),

1/29/19 AC 91 -85B

principal maintenance inspector (PMI), and/or aviation saf ety inspector (ASI) ret ains the

authority to conduct as much review and research wi th respect to any proposed

RVSM -Compliant Aircraft or RVSM -Knowledg eable Pilots requirements as is

warranted. This authority is to ensure safety and regulatory compliance requirements

have been met. Applicants should also understand that i t is the operator’ s responsibility to

ensure documentation reflects the requirements for authoriz ation. A positive s tatement by

the operator detailing any changes made to previously approved programs can assist the

inspector in determining the level of review necessary.

5.4 Applying for an RVSM OpSpec, MSpec, or LOA. A summary of this process is

as follows:

1. The applicant identifies the appropriate FAA office to apply to. ( See

paragraph 5.8.1 .)

2. The applicant determines if a new RVSM authorization is required, or if only

an amendment to an existing RVSM authorization is require d. (See

paragraph 5.8.2 and Appendix F .)

3. If only an amendment to an existing RVSM authorization is required, then the applicant follows the procedures described wi th respect to Authorization

Group I in the Matrix.

4. If the applicant determines a new RVSM authorization is required, then the applicant should first determine who the correct operator will be with respect to applying for and holding the RVSM authorization.

5. Once the appropriate operator is determined, the applicant will determine if it will be using any existing RVSM A uthorization E lements, and if so, will then

follow the process described in paragraph 5.8.4

with respect to Authorization

Group II in the Matrix.

5.5 Providing Evidence for RVSM Authorization. An operator applying for authorization

under the provisions of part 91 appendix G, s ection 3 must provide evidence the aircraft

is RVSM -compliant and the pilots have knowledge sufficient for the conduct of

operations in RVSM airspace.

5.5.1 RVSM -Compliant Aircraft. Aircraft may be produced RVSM -compliant or brought into

compliance through the application of appropriate Service Bulletins (SB), Service Letters (SL), Engineerin g Change Orders (EO), or Supplemental Type Certificates ( STC). (See

Chapter

2.)

1. If the aircraft was manufactured RVSM -compliant, the date of the

airworthiness c ertificate is usually the compliancy date. (For additio nal

information , refer to the Airplane Flight Manual (AFM), AFM Supplement

(AFMS), and/or Type Certificate Data Sheet (TCDS). )

2. If the aircraft was made RVSM -compliant through a n SB, STC, or SL, or

other appropriate methods, the RVSM -compliant date will be listed in the

1/29/19 AC 91 -85B

airframe maintenance log. Include copies of the maintenance record

return- to-service entry.

5.5.2 RVSM -Knowledgeable Pilots . To obtain authorization from the Administrator to conduct

operations in RVSM airspace, the Administrator must find the oper ator to have adopted

RVSM operating policies and/or procedures for pilots (and, if applicable, dispatchers)

and ensure each pilot has adequate knowledge of R VSM requirements, policies, and

procedures with those pilots (and, if applicable, dispatc hers) bein g referred to in this AC

as “RVSM -Knowledgeable Pilots.” ( See Chapter 3.)

5.5.2.1 For an applicant operating only under part 91 or 14 CFR part 125 (including

part 125 Letter of Deviation Authority ( A125 LODA) holders), demonstrating

it has RVSM -Knowledgeable Pilots will consis t of providing evidence to

ensure sufficient knowledge for the conduct of operations in RVSM airspace

as required by part 91 appendix G , section 3(c)(2). The following are

acceptable means for the operator to show the FAA that its pilots have

adequate know ledge of the RVSM oper ating practices and procedures:

• Title 14 CFR part 142 training center certificates without further

evaluation;

• Certificates documenting completion of a course of instruction on RVSM

policy and procedures; and/or

• An operator’s in -house training program.

Note: The FAA, at its discretion, may evaluate a training course prior

to accepting a training certificate.

5.5.2.2 For an appl icant who operates under 14 CFR part 91 subpart K (part 91K ),

121, or 135, in addition to meeting knowledge requirements for part 91

operators, that applicant will need to provide sufficient evidence of initial and

recurring pilot training and/or testing requirements , as well as policies and

procedures allowing the operator to conduct RVSM operations safely as

required in part 91 a ppendix G, section 3(b)(2) and (3).

5.6 RVSM Applicant.

5.6.1 Who is the Correct Person to Apply for and Hold the RVSM Authorization ? The person

exercising operational control of the aircraft during the operation requiring an RVSM authorization is the proper person to be the applicant for that authorization. It is important

to note it is the RVSM applicant’s responsibility to submit a request for RVSM authorization in the name of the person having operational control of the aircraft, not the responsibility of the specific ASI to make such a determination. The following general

information may be useful in assisting the RVSM applicant in determining if the appropriate party has been properly designated as the legal operator with respect to the RVSM authorization request:

1/29/19 AC 91 -85B

5.6.1.1 For commercial and fractional ownership program operations conducted under

parts 91K, 121, 125, and 135, the authorization applicant and holder should be

the operating certificate holder, air carrier certificate holder, or fractional ownership program manage r. The authorization will be issued in the form of

an appropriate OpSpec or MSpec.

5.6.1.2 For noncommercial operations conducted under part 91 and part 125 (A125 LODA holders), the authorization applicant and legal operator should

normally be one of the following persons. The authorization will be issued in

the form of an appropriate LOA:

• A registered owner of the aircraft operating the air craft incidental to its

own non- air transportation business or personal activity.

• A person assuming operational control of the aircraft through a lease or

use agreement for that person’s operation of the aircraft incidental to that person’s own non- air transportation business or personal activity.

Note: The legal operator will generally not be an owner trustee not

operating the aircraf t for its own business ; a management company

that has not accepted a transfer of operational control from the operator ; or a holding company or bank that holds title to the aircraft

solely for the purpose of leasing or transferring operational control of

the aircraft to other persons.

5.6.1.3 It is both possible and common to have multiple operators for part 91, part 91K, and/or part 125/135 aircraft over a short period of time and on a

non-exclusive basis ( e.g., multiple dr y leases for the use of any one aircraft

can be in place at one time). In such instanc es, each individual operator is

required to have an appropriate RVSM authorization issued in its own name in order for that operator to ha ve access to RVSM airspace. For example, if an

aircraft owner elects to l ease the aircraft to a part 135 certificate holder for

charter operations but retain operational control of the aircraft for its own

part 91 flights, then the part 135 certificate holder will hold its RVSM

authorization under its OpSpec for those charter o perations, and the owner

will simultaneously hold a separate RVSM LOA for its own part 91 operations.

5.7 Responsible Person. For part 91 RVSM applicants, the application for authorization to

operate within RVSM airspace must include the designation of a Responsible Person, and may further include the designation of a separate RVSM -POC, as follows:

5.7.1 The operator should designate a person(s) who has the legal authority to sign the RVSM authorization on behalf of the operator and who has adequate knowledge of RVSM

requirements, policies, and procedures. That person may be the individual person who will be the operator, or, if the operator is a legal e ntity, then an officer or employee of

that entity, or a separate person with whom that individual person or ent ity has contracted

1/29/19 AC 91 -85B

to act on behalf of the individual person or legal entity with respect to the RVSM

authorization.

5.7.2 The operator should also designate a person(s) to act as a contact person who has actual day-to-day knowledge of the RVSM -Compliant Aircraf t operations and RVSM

airworthiness status and who the FAA may contact to gather such information when the

need arises.

5.7.3 The operator may use one individual to ful fill both roles as described in paragraphs 5.7.1

and 5.7.2, or the operator may elect to designate separate persons to fulfill these roles.

5.7.4 Whoever the operator designates to fulfill the role described in paragraph 5.7.1 will be designated as the “Responsible Person,” and that Responsible Person will sign LOA s,

as appropriate.

5.7.5 If the operator chooses to use separate individuals, then the person fulfilling the role described in paragraph 5.7.2 will be designated as the “RVSM -POC.” In such an event,

the separate person designated as the RVSM -POC (i.e., someone w ho has not also been

designated as a Responsible Person) will not have any authority to sign the RVSM authorization on behalf of the operator. Additionally, if an operator has designated a separate RVSM -POC, then that is the individual the FAA should first contact with

respect to the operator’s RVSM -Compliant Aircraft op erations and RVSM

airworthiness status.

5.7.6 In any event, the Responsible Person and/or the RVSM -POC should be a person having

ongoing knowledge of the opera tions of the aircraft under the RVSM authorization.

5.7.7 Additionally, it generally is not appropriate to designate an “Agent for Service” with respect to RVSM authorizations being issued to part 91.

Note: Refer to LOA B046 , Operations in Reduced Vertical Separation Minimum

(RVSM) Airspace , for further details regarding Responsible Persons.

5.8 Considerations When Applying for an RVSM OpSpec, MSpec, or LOA.

5.8.1 Preapplication Meeting . The regulations do not require an applicant to participate in a

preapplication meeting. However, an applicant may wish to request a preapplication

meeting if the applicant is unfamiliar with the application process, seeks additional

information with respect to RVSM authorizations, or has other questions concerning how

to move forward with the application process.

5.8.1.1 An applicant who wishes to request a preapplication meeting should make initial contact with the FAA office as follows :

1. Parts 91K, 121, 125 (A125 LODA holders), and 135 operators should notify the appropriate Flight Standards office of their intent

to obtain authorization for RVSM operations.

1/29/19 AC 91 -85B

2. Part 91 operators apply for an RVSM LOA to the appropriate

Flight Standards office with a service area covering the operator’s

primary business address. If your primary business address is not in the United States, apply to the appropr iate International Field

Office (IFO) at

http://www.faa.gov/about/office_org/field_offices/ifo/

. Once on

the w ebsite, click on the service area under each o ffice for

additional informat ion.

5.8.2 Application Requirements . Prior to making a request , determine if the procedures for

Authorization Group I, Authorization Group II, or Authorization Group III should apply.

Note: In your written request to the appropriate Flight Standards office,

use Appendix F , Table F-1, RVSM Decision Matrix , to identify the specific

RVSM Authorization Group for your request. Include sufficient administrative information to allow the FAA inspector to make the necessary form field entries when creating the authorization document. Providing sufficient information to the appropriate Flight Standards office can assist in streamlining the application

process and help prevent processing delays while the inspector waits for the needed information to be submitted.

5.8.3 General Steps for an Application Which Falls Within RVS M Authorization Group I .

5.8.3.1 Prior to making a request for service for a n authorization amendment, each

existing authorization holder should make a positive determination that none

of the previously accepted RVSM Authorization Elements are changing.

5.8.3.2 That authorization holder should then submit a written request to the appropriate Flight Standards office that:

1. States which of the applicable administrative changes are

occurring;

2. Further affirmatively states none of the previously accepted RVSM Authoriza tion Elements forming the basis for the initial issuance of

the affected RVSM authorizatio n have changed or are

changing; and

3. Requests the issuance of an amendment to the existing RVSM authorization acknowledging the administrative change being made.

5.8.3.3 The authorization holder should also provide such further information as requested by the FAA to efficiently process the request.

1/29/19 AC 91 -85B

5.8.4 General Steps for an Application Which Falls Within RVSM Authorization Group II .

5.8.4.1 The applicant should make a positive determination the existing or new

proposed RVSM operator is seeking an RVSM authorization utilizing at least one previously approved/accepted RVSM Authorization Element.

5.8.4.2 Submit a written request to the appropriate Flight Standards office that:

1. Provides complete documentation of an RVSM -compliant

program, including written information evidencing the specific aircraft meets the requirements of an RVSM -Compliant Aircraft;

2. Further specifically states previously accepted RVSM -Knowledgeable Pilots requirements will be used wi th

respect to the operation of the proposed approved RVSM a ircraft

in RVSM airspace, as applicable;

3. Provides such additional information as necessary to evidence compliance with new or different RVSM -Knowledgeable Pilots

requirements (or to be able to gain such approvals); and

4. Asks for the issuance of an RVSM authorization applying to the operation of the aircraft by that proposed RVSM operator.

5.8.4.3 Provide such further information requested by the FAA to efficiently process the request.

5.8.5 General Steps for an Ap plication Which Falls Within RVSM Authorization Group III .

5.8.5.1 In the event a proposed new or existing approved RVSM operator seeks the issuance of an RVSM authorization not based on any existing RVSM Authorization Element, then neither Authoriz ation Group I nor II above

will apply.

5.8.5.2 The applicant should submit a written request to the appropriate Flight

Standards office with sufficient evidence to show its ability to comply with each of the RVSM Authorization Elements in paragraph 5.2

, and the FAA

should process the request as a new and unique request by reviewing all of the materials provided by the applicant to ensure each of the RVSM Authorization Elements have been met.

5.8.5.3 The applicant should also provide such further information requested by the FAA to efficiently process the request .

5.8.6 Other Items for Application .

5.8.6.1 Minimum Equipment List (MEL) . Operators conducting operations under

an MEL should include items pertinent to operating in RVSM airspace.

1/29/19 AC 91 -85B

5.8.6.2 Operating History. An operating history should be included in the

application, if applicable. The applicant should show any events or incidents related to poor altitude -keeping performance indicating weaknesses in

training, procedures, maintenance, or the aircraft G roup intended to be used.

5.8.6.3 Participation in RVSM Altitude -Keeping Performance Monitoring. See

Appendix E

, RVSM Altitude -Keeping Performance Monitoring When

Operating With an R VSM OpSpec, MSpec, or LOA .

5.9 Applicable Forms for the RVSM Authorization Documents.

5.9.1 Parts 121, 125, and 135 Operators . Authorization for parts 121, 125, and 135 operators to

operate in RVSM airspace should be granted through the issuance of an OpSpec from Part B , En Route Authorizations, Limitations, and Procedures ; and Part D , Authorized

Areas of En Route Operations, Limitations, and Provisions . Each aircraft for which the

operator is granted authority should be listed in the OpSpecs. Authorization to conduct RVSM operations in an RVSM a rea of operations new to the operator shoul d be granted

by adding the Part B RVSM OpSpec number to the appropriate area of operations in OpSpec B050, Authorized Areas of En Route Operations, Limitations , and Provisions.

5.9.2 Part 129 Operators . The State of the Operator provides t he operational authorization of

RVSM for part 129. OpSpec A003, Aircraft Authoriz ed for Operations to the

United States , is used to confi rm that the foreign air carrier has operati onal approval. The

State of the Operator must have regulation and supporting guidance documents for the issuance of RVSM. The following are examples of guidance documents the FAA considers to be consistent with ICAO standards on RVSM :

• The current edition of this AC 91- 85; and

• Joint Aviation Authority (JAA) Temporary Guidance Leaflet (TGL ) No. 6 , Guidance

Material on the Approval of Aircraft and Operators for Flight in Airspace Above Flight Level 290 Where a 300 m (1,000 ft) Vertical Separation Minimum Is Applied.

Note: For part 129 operators, inspector guidance for OpSpec A003 is contained in

FAA Order 8900.1, Volume 12, Chapter 2, Section 3 , Part 129 Part A Operations

Specifications .

5.9.3 Part 91K Operat ions. A p art 91K program manager’s authorization for operat ions in

RVSM airspace should be granted through the issuance of an M Spec from Part B and

Part D. Authorization for RVSM is granted by M Spec B046 , Operations in Reduced

Vertical Separation Minimum ( RVSM ) Airspace. Each aircraft for which the operator is

granted authority should be listed in MSpec D092, Airplanes Authorized for Operations

in Designated Reduced Vertical Separation Minimum ( RVSM ) Airspace. Authorization

to conduct RVSM operations in an RVSM area of operations new to the operator should

be granted b y adding the Part B RVSM OpSpec number to the appropriate area of

operations in OpSpec B050 .

1/29/19 AC 91 -85B

5.9.4 Parts 91 and 125 ( A125 LODA Holder) Operators . Part 91 operators and part 125

operators holding a LODA should be issued a n LOA when the initial autho rization

proce ss has been completed.

Note: A LODA is a formal authorization issued by the appropriate Flight

Standards office, authorizing a deviation from specified sections of part 125 and

identified in the Web -based Operations Safety System ( WebOPSS)

(125M database) as an A125 LODA operator.

5.9.5 LOA Exemptions . Operators issued OpSpecs are not required to obtain an LOA for those

operations conducted under part 91 provided that:

1. The aircraft is operated under the operator name listed on the OpSpecs.

2. The fl ight is conducted in an area of operations listed in the OpSpecs.

3. The aircraft is operated under the conditions under which the OpSpecs were granted (e.g., if the operator holds part 121 or 135 OpSpecs, then the pilots used for the part 91 operation must have received part 121 or 135 training) .

4. Each part 91 operation, not associated with a certificated operator, will need an LOA to operate in RVSM airspace.

5.10 Conditions Requiring the Removal of an Authorization.

Note: Examples of reasons for amendment, revocation, or restriction of RVSM

authorization include, but are not limited to, the reasons listed in part 91

appendix G, section 7.

5.10.1 Altitude -Keeping Errors . The incidence of altitude -keeping errors tolerated in an RVSM

environment is very small. It is incumbent upon each operator to take immediate action to rectify the conditions causing the error. The operator should also report the event to the FAA within 72 hours with initial analysis of causal factors and measures to prevent

further events. The FAA should determ ine the requirement for followup reports. Errors

which should be reported and investigated are: T otal Vertical Error (TVE) equal to or

greater than ±300 ft (±90 m), altimetry system error ( ASE ) equal to or greater than

±245 ft (±75 m), and assigned altitude deviation (AAD) equal to or greater than ±300 ft (±90 m).

5.10.2 Error Categories . Altitude -keeping errors fall into two broad categories: 1) errors caused

by malfunction of aircraft equipment, and 2) operational errors. An operator who commits a n altitude -keeping error may be required to forfeit authority for RVSM

operations. If a problem is identified related to one specific aircraft , then RVSM authority

may be removed for the operator for that specific type.

5.10.3 Effective, Timely Response. The operator shoul d make an effective, timely response to

each altitude -keeping error report. The FAA may consider removing RVSM operational

authorization if the operator response to a n altitude -keeping error is not effective or

timely. The FAA should also consider the oper ator’s past performance record in

1/29/19 AC 91 -85B

determining the action to take. If an operator shows a history of operational and/or

airworthiness errors, then authorization may be removed until the root causes of these

errors are shown to be eliminated and RVSM program s and procedures are shown to be

effective. The FAA will review each situation on a case -by-case basis.

5.10.4 Review Relevant OpSpec/MSpec/LOA Paragraphs . Operators may also consider

reviewing all relevant paragraphs of their respective OpSpec, MSpec, or LOA (e.g., A001, Issuance and Applicability ) for elements which may affect RVSM

authorizations.

1/29/19 AC 91 -85B

Appendix A

APPENDIX A. RVSM AIRWORTHINESS CERTIFICATION

CONTENTS

Paragraph Page

A.1 Introduction ............................................................................................................... A-2

A.2 RVSM Flight Envelopes ........................................................................................... A-4

A.3 Group and Non- Group Aircraft ................................................................................ A-6

A.4 Aircraft Syste ms—Group and Non- Group Aircraft ................................................. A-6

A.5 Altimetry System Performance ................................................................................. A-9

A.6 Aircraft System Configura tions: Older “Legacy” Airframes ................................. A-11

A.7 Altimetry Sy stem Performance Substantiation ....................................................... A-15

A.8 Altimetr y System Component Error Budget........................................................... A-16

A.9 Establishing and Monitoring SSEs ......................................................................... A-25

A.10 Maintenance Requirements ..................................................................................... A-29

A.11 RVSM Airworthiness Approval ............................................................................. A-31

A-1

1/29/19 AC 91 -85B

Appendix A

A.1 Introduction.

A.1.1 General . This a ppendix provides guidance on the aircraft airworthiness certification

process for RVSM compliance. Key elements necessary to substantiate the aircraft

systems performance required for RVSM certification are summarized. Differences

between a Group and Non- Group aircraft certification program are presented. A

comprehensive discussion of altimetry system error (ASE) and ASE variation is also provided.

Note: For additiona l information on obtaining RVSM airworthiness certification ,

contact the appropriate FAA Aircraft Certification O ffice (ACO) for guidance.

Contact information for ACO s can be found on the FAA website at

https://www.faa.gov .

A.1.2 Definitions .

1. Air Data Sensor. Line replaceable units (LRU) designed to detect air data

characteristics (e.g., pressure and temperature) to support the air data system

(ADS) of the aircraft.

2. Air Data System (ADS) . Systems used to collect and pr ocess air data

characteristics from various sensors to compute critical air data parameters (e.g., altitude, airspeed, height deviation, and temperature) for use by the pilot and other systems in the aircraft.

3. Aircraft Group. A G roup of aircraft of nominal ly identical design and build

with respect to all details that could influence the accuracy of altitude -keeping

performance.

4. Altimetry System Error (ASE). The difference between the pressure altitude

displayed to the flightcrew when referenced t o Internati onal System of Units

(SI) standard ground pressure setting (29.92 inches of mercury (inHg )/1013.25 hectopascals ( hPa)) and free stream pressure altitude.

5. Altitude -Keeping Capability. Aircraft altitude -keeping performance

expected under nominal environmental operating conditions with proper

aircraft operating practices and maintenance.

6. Altitude -Keeping Performance. The observed performance of an aircraft

with respect to adherence to a flight level (FL).

7. Assigned Altitude Deviation (AAD). The diff erence between the altitude

transmitted by a n Altitude Reporting Mode of Secondary Radar (Mode C )

transponder and the assigned altitude/ FL.

8. Automatic Altitude Control System. Any system designed to automatically

control the aircraft to a referenced pressur e altitude.

9. Avionics Error. The error in the processes of converting the sensed pressure

into an electrical output, of applying any static source error correction (SSEC) as appropriate, and of displaying the corresponding altitude.

A-2

1/29/19 AC 91 -85B

Appendix A

10. Basic Reduced Vertical S eparation Minimum ( RVSM ) Envelope. The

range of Mach numbers and gross weights within t he alti tude ranges FL 290

to FL 410 (or max imum available altitude) where an aircraft is expected to

operate most frequently.

11. Derivative Aircraft. Aircraft of the same m odel type, certified under the

same t ype c ertificate (TC). The aircraft may have different exterior

dimensions, such as fuselage length and wingspan, but share the same

altimetry system architecture. In addition, derivative aircraft share the same SSEC at RVSM FL s. In most cases, derivative aircraft will have differing

flight envelopes, so the RVSM flight envelope defined for the Group must be carefully constructed such that the performance of all models within the Group is captured.

12. Full RVSM Envelope. The entire range of operational Mach numbers, W/ δ,

and altitude values over which the aircraft is operated within RVSM airspace.

13. Instruction s for Continued Airworthiness (ICA). Documentation giving

instructions and requirements for the maintenance essenti al to the continued

airworthiness of an aircraft.

14. Non-Group Aircraft. An aircraft for which the operator applies for approval

on the characteristics of the unique airframe rather than on a G roup basis.

15. Reduced Vertical Separation Minimum (RVSM). Designated airspace,

typically between FL 290 and FL 410, where 1,000 ft vertical separation

between aircraft is applied. This airspace is considered special qualification airspace.

16. Residual Static Source Error (SSE). The amount by which SSE remains

undercorrected o r overcorrected after application of an SSEC .

17. Static Source Error (SSE). The difference between the pressure sensed by

the aircraft static source and the undisturbed ambient pressure.

18. Static Source Error Correction (SSEC). A correction applied to the

altimetry system to produce minimal residual SSE.

19. Total Vertical Error (TVE). Vertical geometric d ifference between the

actual pressure altitude flown by an aircraft and its assigned pressure

altitude (FL).

20. Worst -Case Avionics. The combination of tolerance values, specified by the

manufacturer for the altimetry fit into the aircraft, which gives the largest combined absolute value of avionics errors.

21. W/δ. Aircraft weight, W, divided by the atmospheric pressure ratio, δ.

A-3

1/29/19 AC 91 -85B

Appendix A

A.1.3 An Explanation of W/ δ. Throughout this a ppendix, there are multiple references to the

performance parameter W/ δ. The following discussion is provided for the benefit of

readers who may not be familiar with the use of this parameter.

A.1.3.1 It would be difficult to show all of the gross weight, altitude , and speed

conditions constitut ing the RVSM envelope(s) on a single plot. This is

because most of the speed boundaries of the envelopes are a function of both

altitude and gross weight. As a result, a separate chart of altitude v ersus Mach

would be requir ed for each aircraft gross weight. Aircraft performance

engineers commonly use the following technique to solve this problem.

A.1.3.2 For most aircraft with RVSM altitude capability, the required flight envelope can be collapsed to a single chart, with good approx imation, by use of the

parameter W/ δ (weight divided by atmospheric pressure ratio). This fact is

due to the relationship between W/ δ and the fundamental aerodynamic

variables M and lift coefficient as shown below :

W/δ =1481.4 C

L M2 SREF

where δ = ambient pressure at flight altitude divided by sea level

standard pressure of 29.92126 inches Hg .

W/δ = Weight over Atmospheric Pressure Ratio.

CL = Lift Coefficient (C L = L/qS REF).

L = Lift (in cruise flight L is equal to W) .

q = Dynamic Pressure, q = 1481.4M2 δ.

Dynamic pressure is in the form of lbs/ft2.

M = Mach number .

SREF = Reference Wing Area in square feet .

W is the weight in pounds .

A.1.3.3 As a result, the flight envelope may be collapsed into one chart by simply

plotting W/δ , rather than altitude, versus Mach number. Since δ is a fixed

value for a given altitude, weight can be obtained for a given condition by simply multiplying the W/δ value by δ.

A.1.3.4 Over the RVSM altitude range, it is an accurate approximation to assume th at

position error is uniquely related to Mach number and W/ δ for a given

aircraft.

A.2 RVSM Flight Envelopes.

A.2.1 General . For the purposes of RVSM approval, the aircraft flight envelope is considered in

two parts: 1) the full RVSM envelope, and 2) the basic RVSM envelope. The basic

RVSM envelope is the part of the flight envelope where a ircraft operate the majority

A-4

1/29/19 AC 91 -85B

Appendix A

of time. The full RVSM envelope is the entire range of operational Mach numbers, W/ δ,

and altitude values over which the aircraft is operated within RVSM airspace. In general,

the full RVSM envelope comprises parts of the flight envelope where the aircraft

operates less frequently and where a larger ASE tolerance is allowed.

A.2.2 Full RVSM Envelope . The full RVSM envelope will comprise the entire range of

operational Mach number s, W/δ, and altitude values over which the aircraft can operate

within RVSM airspace. Table A -1 establishes the parameters to consider.

Table A -1. Full R VSM Envelope Boundaries

Lower Boundary

Is Defined By: Upper Boundary

Is Defined By:

Altitude Flight Level ( FL) 290 The lower of the following:

• FL 410

• Airplane maximum certified altitude

• Altitude limited by: cruise thrust; buffet; other aircraft

flight limitations

Mach or Speed The lower of the following:

• Maximum endurance (holding) speed

• Maneuver speed The lower of the following:

• MMO/VMO (maximum

operating limit speed

(Mach/velocity))

• Speed limited by: cruise thrust; buffet; other aircraft

flight limitations

Gross Weight The lowest gross weight

compatible with operation in

RVSM airspace The highest gross weig ht

compatible with operation

in RVSM airspace

A.2.3 Basic RVSM Envelope . The boundaries for the basi c RVSM envelope are the same as

those for the full RVSM envelope except in regard to the upper Mach boundary.

A.2.3.1 For the basic RVSM envelope, the upper Ma ch boundary may be limited to a

range of airspeeds over which the aircraft Group can reasonably expect to

operate most frequently. The manufacturer or design organization should define this boundary for each aircraft Group. It may be defined as equal to the

upper Mach/airspeed boundary defined for the full RVSM envelope or a

specified lower value. This lower value s hould not be less than the Long

Range Cruise (LRC) Mach number plus 0.04 Mach unless limited by available

cruise thrust, buffet, or other aircra ft flight limitations.

A-5

1/29/19 AC 91 -85B

Appendix A

A.2.3.2 The LRC Mach number is the Mach for 99 percent of best fuel mileage at the

particular W/ δ under consideration.

A.3 Group and Non- Group Aircraft.

A.3.1 Group Aircraft . Aircraft comprising a Group must be of nominally identical design and

build with respect to all details that could influence the accuracy of the altitude -keeping

performance. The following conditions should be met:

1. Aircraft should be approved b y the same TC, TC amendment, or

Supplemental Type Certificate (STC), as applicable.

2. For derivative aircraft, it may be possible to use the database from the parent

configuration to minimize the amount of additional data required to show compliance. The extent of additional data required will depend on the nature of the changes between the par ent aircraft and the derivative aircraft .

3. The static system of each aircraft should be installed in a nominally identical manner and position. The same SSE C should be incorporate d in all aircraft of

the Group.

4. The avionics units installed on each aircraft to meet the minimum RVSM equipment requirements ( see paragraph A. 4) should be manufactured to the

manufacturer’s same specification, and have the same equipment part number and software part number (or version and revision).

Note: Aircraft which have avionics units which are of a different

manufacturer or equipment part number, softw are part number (or version and

revision) may be considered part of the Group if the applicant demonstrates to

the appropriate FAA office this standard of avionic equipment provide s

identical or better system performance.

5. The airframe manufacturer or design organization produced or provided the RVSM data package.

A.3.2 Non-Group Aircraft . If an airframe does not meet the conditions of paragraph A.3.1 to

qualify as a member of a Group or i s presented as an individual airframe for approval,

then it must be considered as a Non- Group aircraft for the purposes of RVSM approval.

A.4 Aircraft Systems —Group and Non- Group Aircraft.

A.4.1 Equipment for RVSM Operations . The minimum equipment fit should be as presented

below. Additional examples of aircraft systems found on older, “legacy” airframes are presented in paragraph

A.6.

A-6

1/29/19 AC 91 -85B

Appendix A

A.4.1.1 Two Independent Altitude Measurement Syst ems. Each system should be

comprised and configured with the following elements:

A.4.1.1.1 Static Sources . Cross-coupled static source/system, provided with ice

protection if located in areas subject to ice accretion.

A.4.1.1.2 Altitude Display . Equipment for measuring static pressure sensed by the static

source, converting it to pressure altitude, and displaying the pressure altitude

to the flightcrew.

A.4.1.1.3 Altitude Reporting . Equipment for providing a digitally coded signal

corresponding to the displ ayed pressure altitude, for automatic altitude

reporting purposes. The pressure altitude from which the signal is derived must meet the requirements of paragraphs

A.5.2.1 and A.5.2.2 , or

paragraph A.5.3.2 , as appropriate.

A.4.1.1.4 Altimetry System Components. The altimetry system should comprise all

those elements involved in the process of sampling free stream static pressure and converting it to a pressure altitude output. The elements of the altimetry system fall into two main groups:

•Airframe plus static sources (pitot- static pr obe/static port), including the

area around the static sources in the system design that must be

maintained.

•Avionics and/or instruments.

A.4.1.1.5 Altimetry System Accuracy . The total altimetry system accuracy should

satisfy the requirements of paragraphs A.5.2.1 and A.5.2.2, or paragraph A.5.3.2, as appropriate.

A.4.1.1.6 SSEC . If the design and characteristics of the aircraft and altimetry system are

such that the standards of paragraphs A.5.2.1 and A.5.2.2, or paragraph A.5.3.2, are not satisfied by the location and geometry of the static

sources alone, then suitable SSEC should be applied automatically within the avionic part of the altimetry system. The design aim for SSEC, whether aerodynamic/geometric or avionic, should be to produce a minimum residual SSE, but in all cases it should lead to satisfaction of the standards of

paragraphs A.5.2.1 and A.5.2.2, or paragraph A.5.3.2, as appropriate.

A.4.1.1.7 Output to the Automatic Altitude Control and Altitude Alert Systems .

The altimetry system equipment fit should provide reference signals for

automatic a ltitude control and alerting a t selected altitude. These signals

should be derived f rom an altitude measurement system meeting the full

requirements of this a ppendix. The output may be used either directly or

combined with other sensor signals . If SSEC is necessary to satisfy the

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Appendix A

requirements of paragraphs A.5.2.1 and A.5.2.2, or paragraph A.5.3.2 , then an

equivalent SSEC must be applied to t he altitude control output. The output

may be an altitude deviation signal, relative to the selected altitude, or a

suitable absolute altitude output. Whatever the system architecture and SSEC system, the difference between the output to the altitude control system and the altitude displayed must be minimal.

A.4.1.1.8 System Safety Analysis . During the RVSM approval process, it must be

verified analytically that the predicted rate of occurrence of undetected altimetry system failures does not exceed 1 x 10

-5 per flight -hour. All failures

and failure combi nations whose occurrence would not be evident from

cross -flight deck checks, and which would lead to altitude

measurement/display errors outside the specified limits, need to be assessed against this budget. No other failures or failure combinations need t o be

considered.

A.4.1.1.9 ADS s and Configurations with Multiple Static Source Inputs . Many aircraft

are produced with ADS s making use of three or more static source inputs,

and/or three or more air -data computers (ADC) . Such systems (often referred

to as “triplex” systems or “voting” schemes) are designed with integrated algorithms that monitor and compare the pressures sensed at the static sources. Sources providing “good” pressure values are used in the calculation of corrected altitude. Such configurati ons are acceptable provided at least

two ADS s meet the requirements of paragraphs

A.4.1.1.1 through A .4.1.1.8.

Upon fa ilure of one ADS , a second system must remain fully functional in

compliance with the requirements of paragraphs A.4.1.1.1 through A .4.1.1.8.

A.4.1.2 One Secondary Surveillance Radar (SSR) Altitude Reporting

Transponder. Any transponder meet ing or exceed ing the requirements of

Technical Standard Order (TSO)- C74, Air Traffic Control Radar Beacon

System (ATCRBS) Airborne Equipment, or TSO -C112 , Air Traffic Control

Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment ,

as applicable, in accordance with the operational regulati ons under which the

airplane is approved. An aircraft may be equipped with one or more

transponde rs. If only one is fitted, it should have the capability for switching

to obtain input from either altitude measurement system.

A.4.1.3 An Altitude Alert System. The altitude alert system should be capable of

operation from either of the two required independent a ltitude measurement

systems. The altitude alert system may be comprised of one or more LRU s, or

it may be an integral part of a flight management system (FMS) or flight

management computer (FMC) . The altitude deviation warning system should

signal an alert when the altitude displayed to the flightcrew deviates from

selected altitud e by more than a nominal value.

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Appendix A

1. For aircraft for which application for TC or major change in type

design is on or before April 9, 1997, the nominal value must not be

greater than ±300 ft (±90 m).

2. For aircraft for which application for TC or major chang e in type

design (e.g., STC) i s made after April 9, 1997, the nominal value

should not be gr eater than ±200 ft (±60 m). The overall equipment

tolerance in implementing these nominal threshold values should

not exceed ±50 ft (±15 m).

A.4.1.4 An Automatic Altitude Control System. The automatic altitude control

system is generally comprised of an aut opilot with altitude hold mode. The

automatic altitude control system should be capable of operation from either of the two required independent altitude measurement systems. Paragraph A.6

presents additional options for automatic altitude control configurations found on older, “legacy” aircraf t.

1. As a minimum, a single automatic altitude control system should be installed which is capable of controlling aircraft height within a tolerance band of ±65 ft (±20 m) about the acquired altitude when the aircraft is operated in straight and level flight under

nonturbulent, nongust conditions.

a. Aircraft types for which application for TC is on or before

April 9, 1997, which are equipped with an automatic altitude control

system with FMS/performance management system inputs allow ing

variations up to ±130 ft (±40 m) under nonturbulent, nongust

conditions do not require retrofit or design alteration.

b. If specific tuning is needed for a “legacy” autopilot to meet performance standards in RVSM airspace, this gain scheduling or tuning must not negatively impact th e way the autopilot performs in

other phases of flight and at non- RVSM altitudes. For example, it is

common for older systems to be tuned to meet RVSM tolerance, only to realize they no longer have acceptable vertical performance on a coupled approach.

2. Whe re an altitude select/acquire function is provided, the altitude

select/acquire control panel must b e configured such that an error

of no more than ±25 ft (±8 m) exists between the display selected by the flightcrew and the corresponding output to the cont rol

system.

A.5 Altimetry System Performance.

A.5.1 General . The statistical performance statements of International Civil Aviation

Organization ( ICAO ) Doc 9574 , Manual on a 300 m (1,000 ft) Vertica l Separation

Minimum Between FL 290 and FL 410 Inclusive, for a population of aircraf t are

translated into airworthiness standards by assessment of the characteristics of ASE and

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Appendix A

altitude control. The following standards differ in some r espects from that document, but

they are consistent with the requirements of RVSM and in accordance w ith 14 CFR

part 91 appendix G , section 2 .

A.5.2 Group Approval .

A.5.2.1 The requirements in the basic RVSM envelope are as follows:

1. At the point in the basic RVSM envelope where the mean for ASE

(ASE mean) reaches its largest absolute value, the abso lute value

should not exceed 80 ft (25 m).

2. At the point in the basic RVSM envelope where ASE mean plus

three standard deviations ( ASE3 SD ) reaches its largest absolute

value, the absolute value should not exceed 200 ft (60 m).

A.5.2.2 The requirements in the full R VSM envelope are as follows:

1. At the point in the full RVSM envelope where ASE mean reaches its

largest absolute value, the absolute value should not exceed 120 ft (37 m).

2. At the point in the full RVSM envelope where ASE

mean plus

ASE3 SD reaches its largest absolute value, the absolute value

should not exceed 245 ft (75 m).

3. If necessary, for the purpose of achieving RVSM approval for an

aircraft Group, an operating restriction may be established to

restrict aircraft from conducting RVSM operations in areas of the

full RVSM envelope where the absolute value of ASE mean exceeds

120 ft (37 m) and/or the absolute value of ASE mean plus ASE3 SD

exceed 245 ft (75 m). When such a restriction is established,

identify it in the data package and document it in appropriate

aircraft operating manuals; however, visual or aural warning/indication systems should not be required to be installed on the aircraft.

A.5.2.3 Aircraft types for which application for TC or major change in type design is

made after April 9, 1997, should meet the criteria established for the basic

envelope in the full RVSM envelope. The FAA will consider factors providing an equivalent level of safety in the application of this criteria as

stated in 14 CFR part 21, § 21.21( b)(1)

A.5.3 Non-Group Approval .

A.5.3.1 The standards of par agraphs A.5.2.1, A.5.2.2, and A.5.2.3 cannot be applied to

Non-Group aircraft approval because there can be no Group data with which

to develop airframe -to-airframe variability. Therefore, a single ASE value has

been established that controls the simple sum of the ASE s. In order to control

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Appendix A

the overall population distribution, this limit has been set at a value less than

that for Group approval.

A.5.3.2 The standa rd for aircraft submitted for app roval as Non- Group aircraft, as

defined in paragraph A.3.2 , is as follows:

1. For all conditions in the basic RVSM envelope :

|Residual SSE + worst -case avionics | ≤ 160 ft (50 m )

2. For all conditions in the full RVSM envelope :

|Residual SSE + worst -case avionics | ≤ 200 ft (60 m )

3. “Worst -case avionics ” means that combination of tolerance values,

specified by the manufacturer for the altimetry fit into the aircraft,

which gives the largest combined absolute value of avionics errors. For most systems, this may not be a fixed value over time.

A.5.3.3 An operating restriction may be established to restrict the Non- Group aircraft

from conducting RVSM operations in areas of the full RVSM envelope where the requirements of paragraph A.5.3.2 cannot be met.

A.5.3.4 The ASE airworthiness standards in paragraphs A.5.2 and A.5.3

should not be

confused with the ASE values stated in the altitude -keeping paragraph 4.3.

Paragraphs A.5.2 and A.5.3 represent the ASE performance spe cification for

RVSM airframe airworthiness certification, which is a key element of the

RVSM airplane airworthiness certification process. Paragraph 4.3 presents

performance criteria specified for the RVSM height -monitoring program,

which is an element of the operational quality assurance process. The monitoring program is independent of the airworthiness certification program.

A.6 Aircraft System Configurations: Older “Legacy” Airframes.

A.6.1 Background. This paragraph provides additional guidance regarding configurations found

on older model airplanes (also known as “legacy” airplanes ( e.g., B707, DC -8, older

business jet s, and turboprop aircraft )) for which RVSM approval is sought.

A.6.2 Single Autopilot Installation . Paragraph A.4.1.1.7 states the ADS should provide

reference signals for automatic control and alerting at selected altitude. These signals should preferably be derived from an altitude measurement system meeting the full requirements of this a ppendix. In addition, paragraph A.4.1.1.7 states the altimetry

system must provide an output which can be used by an automatic altitude control system

to control the aircraft at a commanded altitude. The output may be used either directly or combined with other sensor signals. The altitu de control output may be an altitude

deviation signal, relative to the selected altitude, or a suitable absolute altitude output.

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Appendix A

A.6.2.1 A distinction can be made between signals derived from an ADC and signals

derived from an altitude measurement system. P aragraph A.4.1.1.7 does not

mandate the need for dual ADC inputs to the automatic altitude control system.

A.6.2.2 Several airplane model types are equipped with a single autopilot installation. In many cases, the autopilot is only capable of re ceiving altitude hold inputs

from a single source. It has been further noted retrofit ting of these autopilot

installations to receive altitude hold input from additional sources (e.g., another ADC) may yield one or more of the following problems:

1. The retro fit costs are a significant p ercentage of the total worth of

the airframe.

2. The retrofit is not possible without replacement of the autopilot.

3. The retrofit increases ADS complexity, which in turn increases the

scenarios and rates of failure.

4. Upgraded avioni cs (i.e., ADCs) are not available, or the vendors

will not support retrofits.

A.6.2.3 There are two common avionics configurations that may meet RVSM requirements, but do not have dual ADC input to the autopilot. A general description and possible means of complia nce are given below . They are:

1. Figure A -1

, Example of Air Data System/Autopilot Configuration.

2. Figure A -2, Single Air -Data Computer Configuration for

Autopilot Input.

A.6.2.4 Figure A -1 is a typical confi guration for an aircraft using an i ndependent

source for a ltitude hold i nput to the autopilot.

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Appendix A

Figure A-1. Example of Air Data System/Autopilot Configuration

A

.6.2.4.1 The air data sensor is a single LRU activated in altitude hold mode when

the pilot presses an ALT HOLD button, af ter reaching the desired cruise

FL. It is not tied to either ADC or other components comprising the ADS .

The air data sensor provides ∆ H information to the autopilot so the

airplane can maintain the desired altitu de. In some configurations, the pilot

further provides FL information to the autopilot by manually selecting the

displayed altitude (either pilot’s or copilot’s).

A.6.2.4.2 Airplanes equipped with the avionics configuration shown in Figure A-1

may show compliance as fo llows:

1. The airplane must maintain altitude to within ± 65 ft of the

acquired altitude as required by item 1 under

paragraph A.4.1.4 . For RVSM compliance, the ∆ H signal must

be accurate enough such that the airplane maintains the required ± 65 ft altitude deviation specification. This may be

substantiated with flight test data and/or manufacturer’s

specification data.

2. The altitude alerter should function if the air data sensor /ADC

fails. If the altitude alert function is not operational, altitude hold performance must be monitored manually.

3. The air data sensor should be compensated such that an

airspeed change at a cruise FL is not interpreted by the system as change in altitude, causing altitude hold deviation in exces s

of ±65 ft.

4. The altimetry systems meet the RVSM accuracy requirements specified in paragraphs A.5.2.1 and A.5.2.2

, or

paragraph A.5.3.2 , as appropriate.

5. All other requirements set forth in this AC , as appropriate, are

satisfied.

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Appendix A

A.6.2.5 Single ADC input to the autopilot: On a large number of older airplane

models, the avionics configuration is such that one ADC provides altitude hold information to the autopilot ( see Figure A-2). In most models, a second

ADC is also present, or provisions exist so a second can be installed.

Figure A-2. Single Air-Data Computer Configuration f or Autopilot Input

A

.6.2.5.1 Airplanes equipped with the avionics configuration shown in Figure A-2

may show compliance as follows:

1. The airplane must maintain altitude to within ± 65 ft of the

acquired altitude required by item 1 under paragraph A.4.1.4 .

This may be substantiated with flight test data or

manufacturer’s specification data.

2. The altitude alerter should function i f either ADS or ADC fails.

If the altitude alert function is not operational, altitude hold performa nce must be monitored manually.

3. If ADC 1 fails, the airplane mu st be controlled manually until

air traffic control ( ATC ) contingency procedures are executed.

Annunciation should be provided if the pilot deviates ±300 ft from desired altitude. This annunciation must be provided automatically by the altitude alert system. If the altitude alert system is not functioning, altitude hold performance must be

monitored manually.

4. The altimetry systems meet the RVSM accuracy requirements

specified in paragraph s A.5.2.1 and A.5.2.2

, or

paragraph A.5.3.2 , as appropriate.

5. All other requirements in this AC, as appropriate, are satisfied.

A.6.3 Operational Restrictions . Applicants should be aware operational restrictions and/or

changes may also be required for aircraft with avionics con figurations shown in

Figures A-1 and A- 2, to meet all RVSM requirements.

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Appendix A

A.7 Altimetry System Performance Substantiation.

A.7.1 Flight Testing: Group and Non- Group Aircraft .

A.7.1.1 Where precision flight calibrations are used to quantify or verify altimetry

system performance, they may be accomplished by any of the following methods. Flight calibrations should only be performed once appropriate ground checks have been completed, and the certifying authority should agree to the number of flight test conditions. Uncertainties in application of the method must be assessed and taken into account in the data package.

1. Precision tracking radar in conjunction with pressure calibration of the atmosphere at test altitude.

2. Trailing cone.

3. Pacer aircraft. The pacer aircraft must have been di rectly calibrated

to a known standard. It is not acceptable to calibrate a pacer

aircraft by another pacer aircraft.

4. Any other method acceptable to the FAA or approving authority.

Note: Data acquired using elements from the RVSM monitoring

program, such as a ground- based height monitoring unit ( HMU ) or

Aircraft Geometric Height Measurement Element ( AGHME ), or a

portable Global Positioning System ( GPS)-based monitoring unit

(GMU) , is not acceptable for substantiating the ASE performance

specified in paragraphs A.5.2 and A.5.3

A.7.1.2 ASE will generally vary with flight condition. The data package should provide coverage of the RVSM envelope sufficient to define the largest errors in the basic and full RVSM envelopes. Note that, in the case of Group

approval , the worst flight condition may be different for each of the

requirements of paragraphs A.5.2.1 and A.5.2.2

, and each should be

evaluated. Similarly, for Non-Group approval, the worst flight condition may

be different for each of the requirements of paragraph A.5.3.2 and each should

be evaluated.

A.7.2 ASE Variability . In order to evaluate a system against the ASE performance statements

established by the Review of the General Concept o f Separation Panel (RGCSP) (see

Appendix D), it is necessary to quantify the mean and three SD values for ASE,

expressed as ASE mean and ASE3 SD. In order to do this, it is necessary to account for the

different ways in which variations in ASE can arise. The factors affect ing ASE are as

follows and should be considered in the ASE evaluation:

1. Unit-to-unit variability of avionics .

2. Effect of environmental operating conditions on avionics.

3. Effect of transducer and/or avionics component error drift over time.

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Appendix A

4. Effect of flight operating condition on SSE.

5. Airframe -to-airframe variability of SSE, including the following:

• Skin waviness, skin splices/joints, access panels, and radome fit/fair.

• Pitot- static probe variation. This includes manufacturing variation, installation

variation , and probe degra dation (erosion/corrosion) over time.

• Static port variation (for aircraft configured with static sources flush to the skin

surface). Sources of variation include port step- height, degradation, and static port

condition.

• SmartProbes© (integrated ADC /pitot- static probe). Smart probes are s ensitive to

installation variation. They are also capable of complex SSEC algorithms that are

a function of several variables, all of which may be affected by probe condition and installation.

A.7.2.1 Assessment of ASE, whether based on measured or predicted data , must

include the factors listed above in items 1 through 5. The effect of item 4 as a

variable can be eliminated by evaluating ASE at the most adverse flight condition in an RVSM flight envelope.

A.7.2.2 This document does not specify separate limits for the various er ror sources

contribut ing to the mean and variable components of ASE as long as the

overall ASE accuracy requirements of paragraph A.5.2 or A.5.3

are met. For

example, in the case o f Group approval, the smaller the mean of the Group

and the more stringent the avionics standard, the larger the available allowance for SSE variations. In all cases, present the tradeoff adopted in the

data package in the form of an error budget including all significant error

sources.

A.8 Altimetry System Component Error Budget.

A.8.1 General . The ASE budget demonstrates the allocation of tolerances among the various

parts of the altimetry system is, for the particular data package, consistent with the overall

statistical ASE requirements. These individual tolerances within the ASE budget repres ent the maximum error levels for each of the ADS components contribut ing to

ASE. These error levels form the basis of the maintenance procedures used to substantiate the RVSM airworthiness compliance status o f Group or Non- Group aircraft.

The component err or evaluation should be assessed at the worst flight condition in the

basic and f ull envelope.

A.8.2 ASE Components .

A.8.2.1 General. Figure A-3, Altimetry System Error and Its Components, shows the

breakdown of total ASE into its main components, with each error block representing the error associated with one of the functions needed to generate a display of pressure altitude. This breakdown encompasses all ASE s that can

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Appendix A

occu r, although different system architectures may combine the components

in slightly different ways.

A.8.2.1.1 The “Actual Pressure Altitude” is the pressure altitude corresponding to the

undisturbed ambient pressure.

A.8.2.1.2 “Static Source Error ” is the di fference between the undisturbed ambient

pressure and the pressure within the static port at the input end of the static

pressure line.

A.8.2.1.3 “Static Line Error” is any difference in pressure along the length of the line.

A.8.2.1.4 “Pressure Measuremen t & Conversion” is the error associated with the

processes of transducing the pneumatic input seen by the avionics and converting the resulting pressure signal into altitude. As drawn, Figure A-3

represents a self -sensing altimeter system in which the pressure measurement

and altitude conversion functions would not normally be separable. In an ADC system, the two functions would be separate and SSEC would probably

then be applied be fore pressure altitude (Hp) was calculated.

A.8.2.1.5 “Perfect SSEC” would be that correction which compensated exactly for the SSE actually present at any time. If such a correction could be applied, then the resulting value of Hp calculated by the system would differ from the actual altitude only by the static line error plus the pressure measurement and

conversion error. In general, this cannot be ac hieved, so although the “Actual

SSEC” can be expected to reduce the effect of SSE, it will do so imperfectly.

A.8.2.1.6 “Residual S tatic Source Error ” is applicable only in systems applying an

avionic SSEC. It is the difference between the SSE and the correction actually

applied. The corrected value of Hp will therefore differ from actual pressure altitude by the sum of static line error, pressure measu rement and conversion

error, and residual SSE.

A.8.2.1.7 The baro -correction error and the display error occur between Hp and the

displayed altitude . Figure A -3 represents their sequence for a self -sensing

altimeter system. ADC systems can implement baro -correction in a number of

ways that would slightly modify this part of the block diagram, but the errors

would still be associated with either the baro -correction function or the

display function. The only exception is those systems that can be switched to operate the displa y directly from the Hp signal. T hese systems can eliminate

baro-correction error where standard ground pressure setting is used, as in

RVSM operations.

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Appendix A

Figure A -3. Altimetry System Error a nd Its Components

A

.8.2.2 SSE Components. The component parts of SSE are presented in Table A-2,

Static Source Error, with the factors controlling their magnitude.

A.8.2.2.1 The reference SSE is the best estimate of actual SSE, for a single aircraft or an

aircraft Group, obtained from flight calibration measurements. It is variable

with operating condition, characteristically reducing to a family of W/ δ curves

that are functions of Mach. It includes the effect of any aerodynamic

compensation incorporated in the design, and once it has been determined, the

reference SSE is f ixed for the single aircraft or Group, although it may be

revised if substantiated with subsequent data.

A.8.2.2.2 The test techniques used to derive the reference SSE will have some

measurement uncertainty associ ated with them, even though known

instrumentation errors will normally be eliminated from the data. For

trailing -cone measurements, the uncertainty arises from limitations on

pressure measurement accuracy, calibration of the trailing -cone installation,

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Appendix A

and variability in in stallations where more than one is used. Once the

reference SSE has been determined, the actual measurement error is fixed, but

as it is unknown, it can only be handled within the ASE budget as an estimated uncertainty.

A.8.2.2.3 The airf rame variability and pitot- static probe/static port variability

components arise from differences between th e individual airframe and

pitot-static probe/static port, and the example(s) of airframe and probe/port

used to derive the reference SSE.

A.8.2.3 Residual S SE.

A.8.2.3.1 Figure A -3

presents the components and factors. Residual SSE consists of

those error components that make actual SSE different from the reference value ( components 2) , 3), and 4) from Table

A-2), plus the amount by which

the actual SSEC differs from the value that would correct the reference value exactly ( components 2) a), 2)b), and 2) c) from Table

A-3, Residual Static

Source Error (Airc raft with Avionic Static Source Error Correction) ).

A.8.2.3.2 There will generally be a difference between the SSEC that would exactly compensate the reference SSE, and the SSEC that the avionics is designed to

apply. This arises from practical avionics de sign limitations. The resulting

Table A -3 error component 2) a) will therefore be fixed, for a particular flight

condition, for the single aircraft or Gr oup. Additional variable errors 2)b)

and 2)c) arise from those factors caus ing a particu lar set of avion ics to apply

an actual SSEC that differs from its design value.

A.8.2.3.3 The relationship between perfe ct SSEC, reference SSEC, design SSEC , and

actual SSEC is illustrated in Figure A -4

, Static Source Error/Static Source

Error Correction Relationships for Altimetry System Error Where Static Line,

Pressure Measurement, and Conversion Errors Are Zero, for the case where static line errors and pressure measurements and conversion errors are taken as zero.

A.8.2.3.4 Account for factors creat ing variability of SSE relative to the reference

characteristic in two ways : first, as noted for the SSE itself in Table A -2, and

second, for its effect on the application of SSEC as in factor 2 )a)i) of

Table A -3. Similarly, account for the static pressure measurement erro r in two

separate ways : the main effect will be via the “pressure measurement and

conversion,” but a secondary effect will be via factor 2 )a)ii) of Table A-3.

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Appendix A

Table A -2. Static Source Error

(Cause: Aerodynamic Disturbance to Free -Stream Conditions)

Factors Error Components

Airframe Effects

Operating Condition (M, Hp, ∝ , β)*

Geometry: Shape of airframe

Location of static sources

Variati ons of surface contour near

the sources

Variatio ns in fit of nearby doors,

skin panels, or other items 1) Reference SSE values from flight

calibration measurements.

2) Uncertainty of flight calibration

measurements.

3) Airframe -to-airframe variability.

4) Probe/ port-to-probe/ port

variability.

Probe/Port Effects

Operating Condition (M, Hp, ∝ , β)*

Geometry: Shape of probe/port

Manufacturing variations

Installation variations

*M Mach, speed;

Hp pressure altitude;

∝ angle of attack (AOA) ;

β yaw (sideslip).

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Appendix A

Table A -3. Residual Static Source Error (Aircraft w ith Avionic Static Source

Error Correction)

(Cause: Difference Between the Static Source Error Correction Actually Applied

and the Actual Static Source Error)

Factors Error Components

1) As for SSE.

PLUS

2) Source of input data for SSEC function:

a) Where SSEC is a function of Mach:

i) PS sensing: difference in SSEC from

reference SSE.

ii) PS mea surement: pressure

transduction error.

iii) PT errors: mainly pressure transduction error.

b) Where SSEC is a function of a ngle of

attack (AOA) :

i) Geometric effects on alpha:

• Sensor tolerances .

• Installation tolerances .

• Local surface variations .

ii) Measurement error :

• Angle transducer accuracy .

3) Implementation of SSEC function:

a) Calculation of SSEC from input data.

b) Combination of SSEC with uncorrected

height. 1) Static Source Error Components 2 ),

3), and 4) from Table A-2.

PLUS

2a) Approximation in fitting design SSEC to flight calibration reference SSE.

2b) Effect of production variability (sensors and avionics) on achieving design SSEC.

2c) Effect of operating environment

(sensors and avionics) on achieving design SSEC.

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Appendix A

Figure A-4. Static Source Error/Static Source Error Correction Relationships

for Altimetry System Error Where Static Line, Pressure Measurement,

and Conversion Errors A re Zero

A.8.2.3.5

Static line errors arise from leaks and pneumatic lags. In level cruise, these

can be made negligible for a system correctly designed and correctly installed.

A.8.2.3.6 Pressure m easurement and conversion e rror:

1. The functional elements are static pressure transduction (which

may be mechanical, electromechanical, or solid -state) and the

conversion of pressure signal to pressure altitude. The error components are:

• Calibration uncertainty;

• Nominal design performance;

• Unit-to-unit manufacturing variations; and

• Effect of operating environment.

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Appendix A

2. The equipment specification usually covers the combined effect of

the error components. If the value of pressure measurements and conversion error used in the error budget is the worst -case

specification value, then it is not necessary to assess the above components separately. However, calibration uncertainty, nominal design performance, and effect of operating environment can all contribute to bias errors within the equipment tol erance. Therefore,

if it is desired to take statistical account of the likely spread of errors within the tolerance band, it will be necessary to assess their likely interaction for the particular hardware design under consideration.

3. It is particularly imp ortant to ensure the specified environmental

performance is adequate for the intended application.

A.8.2.3.7 Baro -setting error is defined as the difference between the value displayed and

the value applied within the system. For RVSM operation, the value displayed

should always be International Standard Atmosphere ( ISA) standard ground

pressure, but setting mistakes, although part of T VE, are not com ponents

of ASE.

1. The components of the b aro-setting e rror are:

• Resolution of setting knob/display (“Setabilit y”);

• Transduction of displayed value; and

• Application of transduced value.

2. The applicability of these factors and the way they combine

depends on the particular system architecture.

3. For systems in which the display is remote from the pressure measurement f unction there may be elements of the transduction

and/or application or transduced value error components aris ing

from the need to transmit and receive the set ting between the

two locations.

A.8.2.3.8 Imperfect conversion from altitude signal to di splay ca uses display error. The

components are:

• Conversion of display input signal;

• Graticule/format accuracy; and

• Readability.

Note: In self -sensing altimeters, the first of these would normally be

separate from the pressure measurement and conversion error.

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Appendix A

A.8.3 ASE Component Error Budget: Group Approval . Where approval is sought for an aircraft

Group, the data package must be sufficient to show the requirements of paragraphs A.5.1

and A.5.2 are met. Because of the statistical nature of these requirements, the content of

the data package may vary considerably from Group to Group. Paragraph A.8 should

serve as a guide to properly account for ASE sour ces.

A.8.3.1 Establish the mean and airframe -to-airframe variability of ASE based on

precision flight test calibration of a number of aircraft. Where analytical

methods are available, it may be possible to enhance the flight test database and to track subsequent change in the mean and variability based on geometric inspections and bench test s or any other method acceptable to the approving

authority. In the case of derivative aircraft, it may be possible to utilize data from the parent as part of the database ( e.g., a fuselage stretch where the only

difference in ASE

mean between Groups could be reliably accounted for by

analytical means) .

A.8.3.2 All avionics equipment contributing to ASE must be identified by function and part number. The applicant must demonstrate the avionics equipment can meet the requirements established according to the error budget when operating the equipment in the environmental conditions expected to be met during RVSM operations.

A.8.3.3 Assess the aircraft -to-aircraft variability of each error source. The error

assessment may take various forms as appropriate to the nature and magnitude of the source and the type of data available. For example, for some error sources (especially small ones) it may be acceptable to use specification values to represent 3 SD. For other error sou rces (especially larger ones) , a

more comprehensive assessment may be required; this is especially true for airframe error sources where “specification” values of ASE contribution may not have been previously established.

A.8.3.4 In many cases, one or more of the major ASE sources will be aerodynamic in

nature (such as variations in the aircraft surface contour near the static

pressure source). If evaluation of these errors is based on geometric measurements, substantiation should be provide d that the methodology used is

adequate to en sure compliance. (See Figure A -6

, Compliance Demonstration

Ground- To-Flight Test Correlation Process Example.)

A.8.3.5 In showing compliance with the overall requirements, combine the compo nent

error sources in an appropriate manner. In most cases, this will involve the algebraic summation of the mean components of the errors, root sum square (RSS) combination of the variable components of the errors, and summation of the RSS value with the absolute value of the overall mean. Be sure the RSS

combines only variable component error sources independent of each other.

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Appendix A

A.8.3.6 The methodology described above for Group approval is statistical in nature.

This is the result of the statistical nature of the r isk analysis and previous

statistical statements made when developing RVSM. In the context of a

statistical method, a statement that, “Each individual aircraft in the Group

must be built to have ASE contained within ±200 ft ,” does not mean every

airframe s hould be calibrated with a trailing cone or equivalent to demonstrate

ASE is within 200 ft. Such an interpretation would be unduly onerous. However, if any aircraft is identified as having an error exceeding ±200 ft ,

then it should receive corrective actio n.

A.8.4 ASE Component Error Budget: Non -Group Approval . Where an aircraft is submitted for

approval as a Non- Group aircraft, the data should be sufficient to show the requirements

of paragraph A.5.3.2 are met. The data package should specify how the ASE budget has

been allocated between residual SSE and avionics error. The operator and the FAA

should agree on what data will satisfy approval requirements. The following data should

be acquired and presen ted:

1. Calibration of the avionics used in the flight test as required establishing

actual avionics errors contribut ing to ASE. Since the purpose of the flight test

is to determine the residual SSE, specially calibrated altimetry equipment may be used.

2. All a vionics equipment contributing to ASE must be identified by function

and part number. The applicant must demonstrate the avionics equipment can meet the requirements established according to the error budget when operating the equipment in the environmenta l conditions expected during

RVSM operations.

3. Specifications for the installed altimetry avionics equipment indicating the largest allo wable errors must be presented. The error sources shown in items 1

through 5 under paragraph A.7.2 are n ecessary elements of the altimetry

system component error budget for a Non -Group aircraft.

A.9 Establishing and Monitoring SSEs.

A.9.1 General . Paragraph A.8.3.4 requires the methodology used to establish the SSE be

substantiated. Further, maintenance procedures must be established to ensure conformity of both newly manufactured airplanes and those with in- service history. There may be

many ways of satisfying the se requirements; two examples are included below.

A.9.1.1 Example 1: Group Aircraft. One process for showing compliance with

RVSM requirements is shown in Figure A -5, Process for Showing Initial and

Continued Compliance of Airframe Static Pressure System. Figure A-5

illustrates flight test calibrations and geometric inspections will be performed on a given number of aircraft. The flight calibrations and inspections will continue until a correlation between the two is established. Geo metric

tolerances and SSEC will be established to satisfy RVSM requirements. For

aircraft being manufactured, every Nth aircraft will be inspected in detail and

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Appendix A

every Mth aircraft will be flight test calibrated, where N and M are determined

by the manufact urer and agreed to by the approving aut hority. The data

generated by N inspections and M flight calibrations must be used to track the

mean and 3 SD values to ensure continued compliance of the model with the

requirements of paragraphs A.5.2.1 and A.5.2.2 . As additional data are

acquired, they should be reviewed to determine if it is appropriate to change the values of N and M as indicated by the quality of the res ults obtaine d.

A.9.1.1.1 There are various ways in which the flight test and inspection data might be

used to establish the correlation. The example shown in Figure A -6 is a

process in which each of the error sources for several airplanes is evaluated

based on bench tests, inspections, and analysis. Correlation between these evaluations and the actual flight test results would be use d to substantiate the

method. A highly favorable correlation may be used to augment flight test

data, and if appropriate, mitigate the need to conduct periodic flight tests

(every Mth aircraft) as presented in paragraph A.9.1.1 above.

A.9.1.1.2 The method illustrated in Figures A -5 and A -6 is appropriate for new models

since it does not rely on any preexisting database for the Group.

A.9.1.2 Example 2: Group Aircraft. Figure A -7, Process for Showing Initial and

Continued Compliance of Airframe Static Pressure Systems f or In -Service

and New Model Aircraft, illustrates flight test calibrations should be

performed on a given number of aircraft and consistency rules for air data information between all concerned systems verified. Geometric tolerances and SSEC should be esta blished to satisfy the requirements. A correlation should

be established between the design tolerances and the consistency rules. For

aircraft being manufactured, air data information for all aircraft should be checked in term s of consistency in cruise conditions and every Mth aircraft

should be calibrated, where M is determined by the manufacturer and agreed to by the approving authority. The data generated by the M flight calibrations should be used to track the mean and 3 SD values to ensure continued compliance of the Group with the requirements of paragraphs A.5.2.1

and A.5.2.2.

A.9.1.3 Non-Group Aircraft. Where airworthiness ap proval has been based on flight

tests, the continuing integrity and accuracy of the altimetry system must be

demonstrated by periodic g round and flight tests of the aircraft and its

altimetry system at periods to be agreed with the approving authority. However, exemption from flight test requirements may be granted if the applicant can adequately demonstrate the relationship between any s ubsequent

airframe/system degradation and its effects on altimetry system accuracy is understood and adequately compensated/corrected for.

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Appendix A

Figure A-5. Process f or Showing Initial and Continued Compliance of Airframe Static

Pressure System

Fi

gure A-6. Com pliance Demonstration Ground- To-Flight Test Correlation

Process Example

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Appendix A

Figure A -7. Process for Showing Initial and Continued Compliance of Airframe Static

Pressure Systems for In -Service and New Model Aircraft

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Appendix A

A.10 Maintenance Requirements.

A.10.1 General . The data package must include a definition of the procedures, inspections/tests ,

and limits used to ensure all aircraft approved against the data package “conform to type

design .” All future approvals, whether of new build or in- service aircraft, must also meet

the error budget allowances develo ped according to paragraph A.8. The tolerances will be

established by the data package and include a methodology allowing for tracking the mean and SD for new build aircraft .

A.10.1.1 Define compliance requirements and test procedures for each potential source of ASE . Ensure the error sources remain as allocated in the ASE budget.

Provide guidance for corrective action in the event of equipment, test , and/or

inspection failure. Typica l RVSM -specific maintenance procedures include

the following:

1. Verification of a vionics component part numbers.

2. ADS Ground Test. This is a direct assessment of altimetry system

component errors and correct application of the SSEC.

3. Assessment/measurement of the skin surrounding the static sources

(e.g., s kin waviness, skin splices/joints, access panels, radome

fit/fair, and damage ).

4. Inspection of the pitot- static probe or static port (e.g., e rosion,

corrosion, damage, static port orifice degradation, static port step-height, excessive or non- homogenous paint ).

5. SmartProbe

©. Inspection for corrosion, erosion, damage, and

degradation.

A.10.1.2 RVSM -specific maintenance requirements may be necessary to ensure the

automatic altitude control and altitude alerting systems mee t the requirements

of paragraphs A.4.1.3 and A.4.1.4 . The data package should provide data to

substantiate these requirements, if needed.

A.10.1.3 Where an operating restriction has been adopted ( paragraph s A.5.2.2 or

A.5.3.3 , as appropriate ), the data package should contain the data and

information necessary to document a nd establish that restriction. The Airplane

Flight Manual ( AFM ), Pilot O perating M anual (POM), or a n RVSM -specific

flight manual supplement must be revised/created as necessary to reflect this restriction.

A.10.1.4 Any variation/modification from the initial installation affect ing RVSM

approval should be approved by the airframe manufacturer or approved design organization and allowed by the FAA to show RVSM compliance has not been compromised.

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Appendix A

1. ADS modifications. Changes to the components compris ing an

RVSM -complian t ADS cannot be effectively evaluated without the

develo pment of a revised ASE budget. Such modifications must be

approved by the airframe manufacturer or approved design

organization.

2. Automatic a ltitude c ontrol and a ltitude a lert s ystem m odifications.

Changes to components compris ing an RVSM -compliant

automatic altitude control or altitude alert system should be evaluated by the airframe manufacturer or approved design organization.

3. Altitude r eporting. As stated in paragraph A.4.1.2

, any transponder

meet ing or exceed ing the requirements of TSO -C74( ) or

TSO -C112( ), as applicable, in accordance with the operational

regulations under which the airplane is approved.

4. Airframe m odifications. Over time, a RVSM -approved aircraft

may become a candidate for airframe modifications, such as installation of large antennas, radomes, fairings, equipment lockers, winglets, etc. Any modification chang ing the exterior

contour of the aircraft, or potentially impact ing the ADS static

sources and /or pneumatic configuration, aircraft weight , and/or

performance in any manner, must be evaluated by the manufacturer or design organization to ascertain the RVSM compliance status.

A.10.2 Continued Airworthiness Documentation.

A.10.2.1 Aircraft m anufacturers . Review and update the following items ,

as appropriate , to include the effects of RVSM implementation:

1. The Structural Repair Manual (SRM), with special attention to the

areas around the static source, angle of at tack (AOA) sensors , and

doors if their rigging can affect airflow around the previously mentioned sensors.

2. The Master Minimum Equipment List (MMEL).

A.10.2.2 Design o rganizations. The RVSM airworthiness approval will generally take

the form of a n RVSM -specific STC. The STC should contain the following:

1. RVSM -specific maintenance instructions for initial and continued

airworthiness. These maintenance instructions should include procedures ensur ing all sources of ASE and aircraft systems

performance degradation can be assessed and controlled. Paragraphs A.10.1.1, A.10.1.2, and A.10.1.4

summarize key

elements of RVSM -specific maintenance pr ocedures.

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Appendix A

2. An A irplane Flight M anual S upplement (AFMS). The AFMS

should summarize any RVSM -specific performance, configuration ,

and/or operational considerations ( see paragraph A.10.1.3 ) specific

to RVSM performance.

A.10.2.3 The data package should include the required periodicity of the maintenance

procedures presented in paragraph A.10.1.1 and A.10.1.2 , to ensure continued

airworthiness compliance with RVSM requirements.

A.10.2.4 The data package should include descriptions of any special procedures not

covered in paragraph A.10.1 , but may be needed to ensure continued

compliance with RVSM req uirements.

A.10.2.5 To the extent possible, define in- flight defect reporting procedures to facilitate

identification of ASE sources. Such procedures could cover acceptable

differences between primary and alternat e static sources, and others as

appropriate.

A.11 RVSM Ai rworthiness Approval.

A.11.1 General . Obtaining RVSM airworthiness approval is a two -step process. First, the

manufacturer or design organization develops the data package for airworthiness approval and submits the package to the appropriate ACO. Once the ACO approves the data package, the operator applies the procedures defined in the package to obtain authorization from the appropriate Flight Standards office to use its aircr aft to conduct

flight in RVSM airspace. The initial airworthiness review process must consider continued airworthiness requirements. This paragraph summarizes the requirements of the RVSM airworthiness approval data package, and presents a means of complia nce for

a Group or Non -Group aircraft. All aircraft must meet the equipment, configuration , and

performance requirements of paragraph

A.4, and the altimetry system performance

requirements of paragraph A.5.

A.11.2 Contents of the Data Package . As a minimum, the data package should consist of the

following items:

1. A definition of the flight envelope(s) appli cable to the subject aircraft. ( See

paragraph A.2 .)

2. A definition of the Group or Non- Group aircraft to which the dat a package

applies. ( See paragraph A.3.)

3. The data needed to show compliance with the requirements of paragraphs A.4

and A. 5. This data will include most elements presented in paragraphs A.7

through A.9, as appropriate. Older , “legacy” airframes may require guidance

presented in pa ragraph A.6.

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Appendix A

4. The engineering data and com pliance procedures required to:

• Validate all aircraft submitted for airworthiness approval meet RVSM

requirements ; and

• Validate continued in-service RVSM approval integrity of the Group or

Non-Group aircraft.

A.11.2.1 Data Package Approval. All necessary data should be submitted to the

appropriate ACO for action. The operator will be required to implement the procedures for initial and continued airfra me airworthiness compliance, as

presented in the approved data package, to demonstrate the aircraft is in compliance with RVSM performance standards .

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Appendix B

APPENDIX B. TRAINING PROGRAMS AND OPERATING PRACTICES

AND PRO CEDURES

B.1 Introduction. Items listed in this appendix should be standardized and incorporated into

training programs and operating practices and procedures. Certain items may already be

adequately standardized in existing operator programs and procedures. Ne w technologies

may also eliminate the need for certain crew actions. If this is the case, then the intent of this guidance can be considered to be met.

Note: This AC was written for use by a wide vari ety of operator types (e.g.,

14 CFR part s 91, 91K , 121, 125, 129, and 135

operators); therefore, certain items

are included for purposes of clarity and completeness.

B.2 RVSM General.

B.2.1 RVSM Description . RVSM airspace was designed to allow 1 ,000 ft vertical separation

between aircraft operating at f light l evels (FL) at or above FL 290. At 0901 universal

coordinated time ( UTC ) on January 20, 2005, the FAA implemented RVSM between

FL 290−410 (inclusive) in the following airspace: the airspace of the lower 48 states of

the United States, Alaska, Atlantic , and Gulf of Mexico High Offshore Airspace, and the

San Juan flight information region ( FIR). On the same time and date, RVSM was also

introduced into the adjoining airspace of Canada and Mexico to provide a seamless environment for aircraft traversing those borders. In addition, RVSM was implemented on the same date in the Caribbean and South American regions.

B.2.1.1 In the domestic U nited States , Alaska, o ffshore airspace, and the San Juan FIR

RVSM airspace, altitude assignments for direction of flight follow a scheme of odd altitude assignment for magnetic courses 000−179 degrees and even altitud es for magnetic courses 180−359 degrees for flights up to and including

FL 410, as indicated in Figure B -1.

Figure B -1. Flight Level Orientation Scheme

Note: Odd f light levels (FL) : magnetic course 000−179 d egrees.

Even FLs : magnetic c ourse 180−359 degrees.

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Appendix B

B.3 Operating Policies and Procedures in U.S. -Controlled RVSM Airspace. Operators

and pilots should reference the U.S. Aeronautical Information Manual (AIM) , Chapter 4,

Section 6 , Operational Policy/Proc edures for Reduced Vertical Separation Minimum

(RVSM ) in the Domestic U.S., Alaska, Off shore Airspace and the San Juan FIR, and the

U.S. Aeronautical Information Publication (AIP) , En Route Section 7, Oceanic

Operations, as applicable, prior to conducting RVSM operations in U.S.- controlled

RVSM airspace.

B.3.1 Flight Planning . During flight planning, the flightcrew and dispatchers, if applicable,

should pay particular attention to conditions which may affect operation in RVSM

airspace. These include, but may not be limited to:

1. Verifying the aircraft and operator meet RVSM requirements .

2. Annotating the flight plan to be filed with the Air Traffic Service Provider

(ATSP) to show compliance for RVSM operations. T he International Civil

Aviation Organization (ICAO) flight plan , FAA Form 7233- 4, Pre-Flight Pilot

Checklist and International Flight Plan, Item 10, Equipment, should be annotated with the le tter W for filing in RVSM airspace.

• When using FAA Form 7233- 4, operators should ensure that the aircraft’s

registration number (Reg/) is listed in Item 18 (Other Information), if different than that listed in Item 7 (Aircraft Identification).

• For exceptions to the use of FAA Form 7233- 4, refer to the FAA AIM , Chapter 5,

Air Traffic Procedures, for the proper flight codes.

Note: An aircraft or operator not meeting the requirements for RVSM

operations including an aircraft without operable RVSM equipme nt is

referred to as non -RVSM. If either the flightcrew or aircraft do not meet

the requ irements for RVSM , the operator or dispatcher will not file the

RVSM equi pment code in the flight plan and follow the procedures for a

non-RVSM status, including the appropriate pilot- air traffic c ontrol ( ATC )

phraseology in Table B-1

, RVSM Phraseology .

3. Reported and forecast weather co nditions on the route of flight.

4. Minimum equipment requirements pertaining to altitude -keeping systems .

5. Traffic Alert and Collision Avoidance System ( TCAS ) equipage. TCAS

equipage requirements are contained in part 121, § 121.356 ; part 125,

§ 125.224; part 129, § 129.18; and part 135, § 135.180. Part 91 a ppendix G

does not contain TCAS equipage requirements spec ific to RVSM ; however,

part 91 a ppendix G does require that aircraft equ ipped with TCAS II and

flown in RVSM airspace be modified to incorporate TCAS II Version 7.0 or a

later version.

6. If required for the specific aircraft G roup, accounting for any aircraft

operating restrictions related to RVSM airworthiness approval. (See Appendi x A, RVSM Airworthiness Certification, paragraph A.10.1.3

.)

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Appendix B

B.3.2 Preflight Procedures . Accomplish the following actions during preflight:

1. Review maintenance logs and for ms to ascertain the condition of equipment

required for flight in the RVSM airspace. Ensure maintenance action has been

taken to correct defects to required equipment.

2. During the external inspection of aircraft, pay particular attention to the condition of static sources , the condition of the fuselage skin near each static

source , and any other component affect ing altimetry system accuracy. (A

qualified and authorized person other than the pilot ( e.g., a Flight Engineer

(FE) or maintenance personnel ) may perform this check.)

3. Before takeoff:

• The aircraft altimeters should be set to the barometric pressure for local a ltimeter

setting (QNH) and should display a known elevation (e.g., field elevation) within

the limits specified in aircraft operating manu als. The difference between the

known elevation and the elevation displayed on the altimeters should not exceed 75 ft.

• The two primary altimeters should also agree within limits specified by the

aircraft operating manual/ Airplane F light M anual (AFM) , as ap plicable. An

alternative procedure using atmospheric pressure at aerodrome e levation (QFE)

may also be used.

Note: Both checks should be an emphas is item for training materials.

4. Equipment required for flight in RVSM airspace should be operational, and

indication s of malfunction should be resolved.

B.3.3 Procedures Before RVSM Airspace Entry . If any of the required equipment fails prior to

the aircraft entering RVSM airspace, the pilot should request a new clearance to avoid

flight in this airspace. The following equipm ent must be operating normally at entry into

RVSM airspace:

1. Two primary altitude measurement systems.

2. One automatic altitude control system.

3. One altitude alerting device.

Note: The operator or pilot should ascertain the requirement for an operational

transponder and TCAS in each RVSM area where operations are intended.

B.3.4 In-Flight Procedures . Incorporate the following policies into flightcrew training and

procedures , as applicable :

1. Flightcrews should comply with aircraft operating restrictions (if required for the specific aircraft G roup) related to RV SM airworthiness approval. (See

paragraph A.10.1.3

.)

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Appendix B

2. Place emphasis on promptly setting the sub -scale on all primary and standby

altimeters to 29.92 inches of mercury ( inHg )/1013.25 hectopascals ( hPa)

when climbing through the transition altitude and rechecking for proper

altimeter setting when reaching the initial cleared flight level (CFL).

3. In lev el cruise, it is essential the aircraft is flown at the CFL. This requires

particular care is taken to ensure ATC clearances are fully understood and followed. Except in contingen cy or emergency situations, the aircraft should

not intentionally depart from CFL without a positive clearance from ATC.

4. During cleared transition between FLs, the aircraft should not be allowed to

overshoot or undershoot the CFL by more than 150 ft (45 m).

Note: It is recommended the level -off be accomplished using the altitude

capture feature of the automatic altitude control system, if installed.

5. An automatic altitude control system must be operative and engaged during

level cruise, except when circumstances such as the need to retrim the aircraft or turbulence require disengagement. I n any event, adherence to cruise

altitude should be done by reference to one of the two primary altimeters.

6. The altitude alerti ng system must be operational.

7. At cruise FL, the two primary altimeters should agree within 200 ft (60 m) or

a lesser value if specified in the aircraft operating manual. (Failure to meet

this condition will require that the altimetry system be reported as defective and notified to ATC .) Note the difference between the primary and standby

altimeters for use in contingency situatio ns.

8. At intervals of approximately 1 hour, make cross -checks between the primary

altimeters and the standby altimeter.

a. The normal pilot scan of flight deck instruments should suffice for altimeter

cross -checking on most flights.

b. When operating in surveillance airspace ( Radar /Automatic Dependent

Surveillance- Broadcast ( ADS -B)), the initial altimeter cross -check should be

performed after level -off.

c. In oceanic and remote continental (procedural) airspace, a cross -check should be

performed and recorded in the vi cinity of the point where oceanic and remote

continental navigation begins (e.g., on coast out). The readings of the primary and

standby altimeters should be recorded and available for use in contingency situations.

d. Some aircraft have automatic comparators that compare the two primary altimetry

systems. The comparators include a monitoring, w arning, and fault function. The

faults may be recorded automatically by the system, but a record of the differences in the primary altimetry systems may not be easily d erived.

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Appendix B

Note: In oceanic and remote continental (procedural) airspace, e ven if the

aircraft is equipped with automatic comparators , the crew should be recording

the altimeter cross -checks for u se in a contingency situation.

9. Normally, the altimetry system being u sed to control the aircraft should be

selected to provide the input to the altitude -reporting transponder transmitting

information to ATC.

10. If ATC notifies the pilot of an assigned altitude deviation (AAD) error equal

to or exceed ing 300 ft (90 m) , then the pilot should take action to return to

CFL as quickly as possible.

B.3.5 Pilot C ontroller Phraseology for RVSM O perations . See Table B-1.

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Appendix B

Table B-1. RVSM 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 n on-RVSM status, as follows:

a. On the initial call on any frequency in the RVSM

airspace;

b. In all requests for flight level (FL) changes

pertaining to FLs within the RVSM airspace;

c. In all read backs to FL clearances pertaining to FLs

within the RVSM airspace; and

d. In read back of FL clearances involving climb and

descent through RVSM airspace (FL 290−410). Negative RVSM (s upplementary information,

e.g., “Certification flight”).

Pilot report of one of the following after entry into RVSM

airspace: all primary altimeters, automatic altitude control

systems , or altitude alerters have failed.

(Refer to AIM Paragraph 4 -6-9, Contingency Actions:

Weather Encounters and Aircraft System Failures that Occur

After Entry into RVSM Airspace.)

NOTE: This phrase is to be used to convey both the init ial

indication of RVSM aircraft system failure and on initial contact on all frequencies in RVSM airspace until the

problem ceases to exist or 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

(CFL) due to weather encounter.

(Refer to AIM paragraph 4 -6-9.) *Unable RVSM due (state reason) (e.g., turbulence,

mountain wave) .

ATC requesting pilot to confirm that an aircraft has regained

RVSM -approved status or a pilot is ready to resume RVSM . Confirm able to resume RVSM .

Pilot ready to resume RVSM after aircraft system or weather

contingency . Ready to resume RVSM .

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Appendix B

B.3.6 Contingency Procedures After Entering RVSM Airspace. The flightcrew , after realizing

that they no longer can comply with RVSM requirements (aircraft system failure,

weather, lost com, etc.) , must request a new clearance from the controller/radio operator

as soon as the s ituation allows. If a new clearance is not available or the nature of the

emergency requires rapid action , the pilot should notify ATC of their action and

contingenc y procedures. Operators should refer to the RVSM section of the AIM when

experiencing abnor mal situations and implementing conti ngency procedures. It is also the

responsibility of the crew to notify ATC when the implementation of the contingency procedures is no longer required.

Table B -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:

• Notify ATC and request assistance as detailed below.

• Maintain CFL, to the extent possible, while evaluating the situation.

• Watch for conflicting traffic both visually and by reference to TCAS, if equipped .

• Alert nearby aircraft by illum inating exterior lights (commensurate with aircraft limitations).

Severe Turbulence and/or Mountain Wave Activity (MWA) Induced

Altitude Deviations of Approximately 200 Feet or G reater

Pilot will:

• When experi encing severe turbulence and/or MWA

induced altitude deviations of approximately 200 ft

or greater, pilot will contact ATC and state “Unable

RVSM due [state reason ]” (e.g., turbulence,

mountain wave) .

• If not issued by the controller, request vector clear

of traffic at adjacent FLs .

• If desir ed, request FL change or reroute .

• Report location and magnitude of turbulence or

MWA to ATC . Controller will:

• Vector aircraft to avoid merging target with traffic at adjacent FLs , traffic permitting .

• Advise pilot of conflicting traffic .

• Issue FL change or reroute, traffic permitting .

• Issue Pilot Weather Report ( PIREP ) to other

aircraft .

MWA Encounters – General

Pilot actions:

• Contact ATC and report experiencing MWA .

• If so desired, pilot may request a n FL change or

reroute .

• Report location and magnitude of MWA to ATC .

See Appendix D , Severe Turbulence and Mountain

Wave Activity . Controller actions:

• Advise pilot of conflicting traffic at adjacent FL .

• If pilot requests, vector aircraft to avoid merging target with traffic at adjacent RVSM FLs, traffic

permitting .

• Issue FL change or reroute, traffic permitting .

• Issue PIREP to other aircraft .

NOTE : MWA encounters do not necessarily result in altitude deviations on the order of 200 ft. The guidance

below is intended to address less significant MWA encounters.

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Appendix B

Wake Turbulence Encounters

Pilot should:

• Contact ATC and request vector, FL change, or,

if capable, a lateral offset .

See Appendix D . Controller should:

• Provide 2, 000 ft vertical separation or appropriate

horizontal separation .

• Clear aircraft out of RVSM airspace unless

operational situation dictates otherwise .

“Unable RVSM Due Equipment”

Failure of Automatic Altitude Control System, Altitude Alerter , or All Primary Altimeters

Pilot will:

• Contact ATC and state “Unable RVSM d ue

equipment .”

• Request clearance out of RVSM airspace unless

operational situation dictates otherwise . Controller will:

• Provide 2,000 ft vertical separation or appropriate

horizontal separation .

• Clear aircraft out of RVS M airspace unless

operational situation dictates otherwise .

One Primary Altimeter Remains Operational

Pilot will:

• Cross -check standby altimeter .

• Notify ATC of operation with single primary

altimeter .

• If unable to confirm primary altimeter accuracy,

follow actions for failure of all primary altimeters . Controller will:

• Acknowledge operation with single primary

altimeter .

Transponder Failure

Pilot will:

• Contact ATC and request authority to continue to operate at CFL .

• Comply with revised ATC clearance, if issued .

NOTE : Part 91, § 91.215

, ATC Transponder and

Altitude Reporting Equipment and Use, regulates

operation with the transponder inoperative. Controller will:

• Consider request to continue to operate at CFL .

• Issue revised clearance, if necessary .

Note 1: For an expanded description and explanation of severe turbulence and MWA , see

Appendix D.

Note 2: Transponder or TCAS Failure : In air space not controlled by the United States ,

the provider States will determine the specific actions operators should take in the event

of transponder or TCAS failure while operating in RVSM airspace.

B.3.7 Postflight. In making maintenance logbook entries against malfunctions in

altitude -keeping systems, the pilot should provide sufficient detail to enable maintenance

to effectively troubleshoot and repair the system. The pilot should detail the actual defect

and the c rew action taken to try to isolate and rectify the fault. Note the following

information when appropriate:

1. Primary and standby altimeter reading.

2. Altitude selector setting.

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Appendix B

3. Subscale setting on altimeter.

4. Autopilot used to control the airplane and any diffe rences when the alternate

system was selected.

5. Differences in altimeter readings if alternate static ports selected.

6. Use of air -data computer (ADC) selector for fault diagnosis procedure.

7. Transponder selected to provide altitude information to ATC and any

difference if alternate transponder or altitude source is manually selected.

B.4 Accommodation of Non -RVSM Aircraft. Operators must be authorized and aircraft

must be compliant to fly in designated RVSM airspace with limited exceptions. An

operator not author ized for RVSM operations or an operator/aircraft without operable

RVSM equipment is referred to as non- RVSM. The operator or dispatcher must not file

the RVSM equipment code in the flight plan. The pilot of a non- RVSM aircraft must

inform the controller of the lack of RVSM approval in accordance with the direction provided in Table B-1

B.4.1 The procedures for accommodation of non- RVSM a ircraft in RVSM airspace for

operations in the domestic United States , Alaska , offshore airspace, and the San Juan FIR

are contained in the FAA AIM , Paragraph 4- 6-10, Procedures for Accommodation of

Non-RVSM Aircraft . For operations within oceanic airspace , refer to the U.S. AIP,

En Route Section 7.

B.4.2 Specific categories of non -RVSM a ircraft m ay be accommodated . Subject to FAA

approval and clearance, the following categories of non- RVSM aircraft ma y operate in

domestic U.S. RVSM airspace provided they have an operational transponder.

1. Department of Defense (DOD) aircraft .

2. Active air ambulance flights utilizing the “MEDEVAC” call sign .

3. Aircraft capable of climbing/descending through RVSM FLs without

level -off.

B.4.3 In addition to those aircraft identified in paragraph B.4.2 above, in oceanic and offshore airspace controlled by the U nited States , the following non- RVSM aircraft may be

accommodated on a workload permitting basis with prior coordination:

1. Aircraft being initially delivered to the State of Registry or State of the Operator; and

2. Aircraft that was formerly RVSM -compliant but has experie nced equipment

failure being fl own to a maintenance facility.

B.5 Minimum Equipment List (MEL) . Operators conducting operations under an MEL

adopted from the Master Minimum Equipment List (MMEL) should include items pertinent to operating in RVSM airspace.

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Appendix B

B.6 Oceanic Operations . In general , RVSM procedures in oceanic airspace are no different

from those in domestic airspace. However, s ome regional differences apply. Operators

should be cognizant of differences for the area in which they are intending to operate.

Note: ICAO Doc 7030 , Regional Supplementary Procedures, provides differences

for individual regions of the world.

B.6.1 Strategic Lateral Offset Pr ocedures (SLOP) . SLOP are approved oceanic procedures

allow ing aircraft to fly on a parallel track to the right of the centerline relative to the

direction of flight to mitigate the lateral overlap probability due to increased navigation

accuracy and wake turbulence encounters. Unless specified in the separation standard, an

aircraft’s use of these procedures does not affect the application of prescribed separation standards. Implementation of SLOP must be coordinated among the States involved.

Procedures for the conduct of SLOP are contained in ICAO Doc

4444 , Procedures for Air

Navigation Se rvices, Air Traffic Management , Chapter 16.5, Strategic Lateral Offset

Procedures (SLOP).

Note: In domestic U.S. airspace, pilots must request clearance to fly a lateral

offset. Strategic lateral offsets flown in oceanic airspace do not apply. ( Refer to

FAA AIM Paragraph 4- 6-7, Guidance on Wake Turbulence.)

B.6.2 Special Procedures for In -Flight Contingencies in Oceanic Airspace . Special procedures,

including weather deviation procedures , can be found in ICAO Doc 4444, Chapter 15,

Procedures Related to Emergencies, Communication Failure and Contingencies .

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Appendix C

APPENDIX C. OPERATIONS OUTSIDE O F U.S. -CONTROLLED AIRSPACE

C.1 Introduction. RVSM was initially implemented in North Atlantic m inimum navigation

performance s pecifications (MNPS) airspace in March 1997 (MNPS a irspace was later

renamed North Atlantic High Level Airspace (NAT HLA) ). Since then , RVSM

operations have been implemented worldwide. Operators should expect to have to

comply with RVSM procedures whenever operating at FL 290 to FL 410 inclusive.

C.2 ICAO Doc 9574, Manual on a 300 m (1,000 f t) Vertical Separation Minimum

Between FL 290 and FL 410 Inclusive. RVSM guidance to State authorities can be found in ICAO Doc 9574 . The operating procedures specified in Appendix B

, Training

Programs and Operating Practices and Procedures, are consistent with this guidance.

C.3 ICAO Doc 7030, Regional Supplementary Procedures , and State -Specific Guidance.

While States make every effort to harmonize RVSM implementations, there are

differences that are highlighted in State guidance.

C.3.1 Operators are res ponsible for knowing the RVSM procedures in the areas of intended

operation. Operators starting RVSM operation in an RVSM area of operation new to them should ensure their RVSM programs incorporate RVSM policy and procedures

unique to the new area of operations.

C.3.2 Operators should review ICAO Doc 7030

and State AIPs prior to starting RVSM

operations in an area new to the operator.

C.4 RVSM Met ric FLs, China and Mongolia.

C.4.1 China RVSM. Metric RVSM was implemented in the Shenyang, Beijing, Shanghai,

Guangzhou, Kunming, Wuhan, Lanzhou, and Urumqi FIRs and Sector AR01 (Island

airspace) of the Sanya control area ( CTA ) between 8 ,900 meters ( m) (FL 291) and

12,500 m (FL 411) inclusive. The airspace between 8,900 m (FL 291) and 12,500 m

(FL 411) is defined as RVSM airspace. China RVSM airspace is exclusive RVSM

airspace; aircraft that are not RVSM -compliant may not operate into China RVSM

airspace between 8,900 m (FL 291) and 12,500 m (FL 411).

• ATC will issue the FL clearance in meters, but the aircraft shall be flown using the

FL in feet . The China RVSM FLAS and specific RVSM procedures can be found in

the State AIP.

• Operators must review the State AIP pr ior to operating in these areas.

Note: Operators can find RVSM- related documents , including the RVSM

Aeronautical Information Circular (AIC) Nr. 06/07, Policy and Procedures of

RVSM in China Airspace, at http://www.chinarma.cn/documenten/index.jhtml .

C.4.2 Mongolia RVSM. Metric RVSM wa s implemented in the Ulaanbaatar FIR between

8,900 m (29 ,100 ft) and 12,500 m (41 ,100 ft) inclusive. The a irspace between 8 ,900 m

(29,100 ft) and 12,500 m (41 ,100 ft) is defined as RVSM airspace. Mongolia RVSM

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Appendix C

airspace is exclusive RVSM airspace, and aircr aft that are not RVSM -compliant may not

operate into Mongolia RVSM airspace between 8 ,900 m (29,100 ft) and 12 ,500 m

(41,100 ft).

C.4.2.1 ATC will issue the FL clearance in meters, but the aircraft shall be flown

using the FL in feet . The Mongolia RVSM FLAS and specific RVSM

procedures can be found in the Civil Aviation Authority (CAA) of Mongolia

AIC 03/11 , Policy and Procedures of Reduced Vertical Separation Minimum

(RVSM) in the Airspace of Mongolia .

Note: Operators can find the AIC on the FAA RVSM documentation web page at

https://www.faa.go v/air_traffic/separation_standards/rvsm/documentation/ .

C.5 U.S.-Registered Operators Based Outside of U.S. -Controlled Airspace.

C.5.1 U.S.-registered operators that are based or routinely operate in airspace not controlled b y

the United States must be cognizant of the RVSM policies and procedures in the areas of

intended operation.

C.5.1.1 Operators wishing to operate under the provisions of 14 CFR part 91

appendix G, section 9 must meet all of the requirements, including RVSM

altitude -keeping performance standards as specifi ed in part 91 appendix G,

section 9(b), prior to conducting RVSM operations outside of U.S.- controlled

airspace.

C.5.1.2 The aircraft’s altitude -keeping performance must have been monitored within

the previous 24 months in airspace the FAA can monitor the aircraft

ADS -B OUT signal and found to be in compliance . A map of FAA ADS -B

monitored airspace can be found at

https://www.faa.gov/nextgen/programs/adsb/coverageMap/ .

Note: The FAA may also expand the airspace in which we collect

altitude -keeping performance data via ADS -B through collaboration

with other ANSP s.

C.5.1.3 U.S.-registered operators may obtain monitoring performance from the FAA

altitude -keeping performance website at

https://www.faa.gov/air_traffic/separation_standards/naarmo/ .

C.5.2 Operators of a irplanes that do not routinely operate in airspace where sufficient ADS -B

data is available to the FAA to determine RVSM performance, or when a foreign country

requires a specific approval , may seek an RVSM authorization via OpSpec, MSpec , or

LOA under the provisions of part 91 appendix G, s ection 3. ( See Chapter 5 , Operators

Applying for RVSM OpSpecs, MSpecs, or LOAs .)

C-2

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Appendix D

APPENDIX D. SEVERE TURBULENCE AN D MOUNTAIN WAVE ACTIVITY

D.1 Introduction/Explanation. The information and practices in this paragraph are provided

to emphasize to pilots the importance of taking appropriate action in RVSM airspace when aircraft experience severe turbulence and/or Mountain Wave Activity ( MWA ) that

is of sufficient magnitude t o significantly affect altitude -keeping.

1. Severe turbulence causes large, abrupt changes in altitude and/or attitude usually accompanied by large variations in indicated airspeed. Aircraft may be momentarily out of control. Encounters with severe turbulenc e must be

remedied immediately in any phase of flight. Severe turbulence may be associated with MWA.

2. Also refer to the FAA AIM

, Chapter 4, Section 6, Operational

Policy/Procedures for Reduced Ve rtical Separation Minimum ( RVSM ) in the

Domestic U.S., Alaska, Offshore Airspace and the San Juan FIR.

D.1.1 MWA . Significant MWA occurs both below and above the floor of RVSM airspace,

FL 290. MWA often occurs in western states in the vicinity of mountain range s. 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 highly localized and short-lived.

D.1.1.1 Wave A ctivity I s Not Necessarily L imited to the V icinity of M ountain

Ranges. Pilots experiencing wave activity anywhere that significantly affects altitude -keeping can follow the guidance provided below.

D.1.1.2 In-Flight MWA I ndicators ( Including T urbulence). Indicators that the

aircraft is being subjected to MWA are:

• Altitude excu rsions and/or airspeed fluctuations with or without associated

turbulence.

• Pitch and trim changes required to maintain altitude with accompanying

airspeed fluctuations.

• Light to severe turbulence, depending on the magnitude of the MWA.

D.1.2 Application of Mergi ng Target Procedures .

D.1.2.1 Explanation of Merging Target Procedures. ATC will use “merging target

procedures” to mitigate the effects of both severe turbulence and MWA.

En route controllers will advise pilots of potential traffic that they perceive may fly dire ctly above or below his or her aircraft at minimum vertical

separation . In response, pilots are given the option of requesting a radar vector

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Appendix D

to ensure their radar target will not merge or overlap with the traffic’s radar

target.

D.1.2.2 Priority . The provision of “merging target procedures” to mitigate the effects

of severe turbulence and/or MWA is not optional for the controller, but rather

is a priority responsibility. Pilot requests for vectors for traffic avoidance

when encountering MWA or pilot reports of “Un able RVSM due turbulence

or MWA” are considered first priority aircraft separation and sequencing

responsibilities. The controller’s first priority is to separate aircraft and issue

safety alerts.

D.1.2.3 Explanation of the T erm “ Traffic P ermitting.” The contingency actions for

MWA and severe turbulence detailed in this a ppendix state that the controller

will “vector aircraft to avoid merging targets with traffic at adjacent FL s,

traffic permitting.” The term “traffic permitting” is not intended to imply that

mergi ng target procedures are not a priority duty. The term is intended to

recognize t here are circumstances 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. Further

direction given is: “That action which is most critical from a safety standpoint

is performed first.”

D.1.3 TCAS Sensitivity . For both MWA and severe turbulence encounters in RVSM airspace,

an additional concern is the sensitivity of collision avoidance systems when one or both

aircraft operating in close proximity receive TCAS advisories in response to disruptions

in altitude hold capability.

D.1.4 Preflight T ools. Sources of observed and forecast information that can help th e pilot

ascertain the possibility of MWA or severe turbulence are Forecast Winds and

Temperatures Aloft (FD), Area Forecast (FA), Graphical Turbulence Guidance (GTG),

significant meteorological information ( SIGMET ) and Pilot Weather Reports ( PIREP ).

D.1.5 Pilot Actions When Encountering Weather (e.g., Severe Turbulence or MWA) .

D.1.5.1 Weather Encounters Inducing Altitude Deviations of A pproximately

200 F eet. When the pilot experiences weather -induced altitude deviations of

approximately 200 ft, the pilot will contact ATC and state “Unable RVSM

due [ state reason ]” (e.g., turbulence, MWA ).

D.1.5.2 Severe Turbulence ( Including T hat A ssociated With MWA). When pilots

encounter severe turbulence, they should contact ATC and report the situation.

Until the pilot reports clear of severe turbulence, the controller will apply merging target vectors to one or both passing aircraft to prevent their targets

from merging.

D-2

1/29/19 AC 91 -85B

Appendix D

Example: “Yankee 123, FL 310, unable RVSM due severe

turbulence.”

“Yankee 123, fly heading 290; traffic twelve o’cloc k, 10 miles,

opposite direction; eastbound MD -80 at FL 320” (or the controller

may issue a vector to the MD -80 traffic to avoid Yankee 123).

D.1.5.3 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 ft or greater, the pilot will request a vec tor to avoid

traffic. 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

merging .

Example: “Yankee 123, FL 310, unable RVSM due mountain wave.”

“Yankee 123, f ly heading 290; traffic twelve o’clock, 10 miles,

opposite direction; eastbound MD -80 at FL 320” (or the controller

may issue a vector to the MD -80 traffic to avoid Yankee 123).

D.1.5.4 FL Change or Re route. To leave airspace where MWA or severe turbulence

is bein g encountered, the pilot may request a n FL change and/or re route, if

necessary.

D.2 Wake Turbulence.

D.2.1 Background.

D.2.1.1 Pilots should be aware of the potential for wake turbulence encounters in RVSM airspace. Experience gained since 1997 has shown that such encounters in RVSM airspace are generally moderate or less in magnitude.

D.2.1.2 Prior to Domestic RVSM ( DRVSM ) implementation, the FAA established

provisions for pilots to report wake turbulence events in RVSM airspace using the National Aeronautics and Space Adm inistration ( NASA) Aviation Safety

Reporting System (ASRS). A “Safety Reporting” section established on the FAA RVSM Documentation web page provides contacts, forms, and reporting

procedures.

D.2.1.3 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 seven reports in a 10 -month period). In addition,

they found that reported wake turbulence was generally similar to moderate clear air turbulence.

D-3

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Appendix D

D.2.2 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. Appr oximately 10−30 miles after passing 1,000 ft below opposite -direction

traffic.

c. Approximately 10−30 miles behind and 1,000 ft 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 wingspan upwind generally can move the

aircraft out of the immediate vicinity of another aircraft’s wake vortex.

Note 2: In domestic U.S. airspace, pilots must request clearance to fly a lateral

offset. Strategic lateral offsets flown in oceanic airspace do not apply.

D.3 Pilot/Controller Phraseology. See Appendi x B, Training Programs and Operating

Practices and Procedures , Table B-1, RVSM Phraseology, for a table of pilot/controller

phrase ology.

D.4 Contingency Actions. See Appendix B, Table B -2, Contingency Actions: Weather

Encounters and Aircraft System Failures That Occur After Entry into RVSM Airspace, for a table of conting ency actions.

D-4

1/29/19 AC 91 -85B

Appendix E

APPENDIX E. RVSM ALTITUDE -KEEPING PERFORMANCE MONITORING WHEN

OPERATING WITH A N RVSM OPSPEC, MSPEC , OR LOA

E.1 Introduction. This appendix explains how an operator can meet the requirements for

altitude -keeping performance monitoring when operating under the provisions of 14 CFR

part 91 appendix G , section 3 when issued an OpSpec, MSpec, or LOA.

Note: If the operator’s aircraft is equipped with a qualified ADS- B OUT system

and wishes to conduct operations under the provisions of part 91 appendix G,

section 9 , see Chapter 4 , Authorizations for Operators of RVSM Aircraft

Equipped With a Qualified ADS- B OUT System .

E.1.1 All O perators W ishing to Conduct Operations in RVSM-D esignated A irspace A re

Required to P articipate in RVSM H eight -Monitoring.

E.1.1.1 Part 91 appendix G, s ection 3 stipulates how the operator, in a manner

prescribed by the Administrator, must provide evidence that “[i]t is capable to

operate and maintain each aircraft or aircraft Group for which it applies for

approva l to operate in RVSM airspace.” Height -monitoring is the method

prescribed to verify ASE remains within required performance limits.

E.1.2 When D o I H ave to G et My A irplanes Monitored ? U.S.-registered operators are required

to conduct initial height- monitoring within 6 months of the authorization date of issue

and must conduct height-monitoring every 2 years , or within intervals of

1,000 flight-hours, whichever period is longer.

1. Monitoring is not required prior to being granted operational approval.

2. Evidence of previous successful monitoring of an airplane may be used to

meet the monitoring requirements.

3. When calculating the 1,000-hour provision of the M inimum Monitoring

Requirement (MMR) , the calculation of the flight time should be from the last

satisfactory height -monitoring date on record.

E.1.3 How Many Airplanes Need to B e Monitored?

1. An operator with multiple airplanes may not need to have all airplanes monitored. For height-monitoring, only a sampling of airframes of each airplane type need to be monitored.

2. To determine the number of airframes each operator is required to have monitored, use the RVSM Minimum Monitoring Requirement (MMR) chart

(Refer to the RVSM Documentation w eb page at

https://www.faa.gov/air_traffic/separation_standards/rvsm/documentation/ .)

Note: An operator that is unable to meet the minimum height- monitoring

requirements within the specified timeframe should contact the appropriate Flight

Standards office prior to exceeding the specified timeframe.

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Appendix E

E.1.4 How Do I Get My A irplanes M onitored?

1. An operator may choose to fly with a trained technician from an

FAA -approved RVSM monitoring support provider utilizing a GMU on board

the airplanes.

2. An operator may fly an airplan e through an established ground- based

height -measuring system. Currently , ground- based systems exist in:

• North America, AGHME (requires Mode S equipment); or approved

ground -based height -measuring systems in other regions ( e.g., Europe or Japan) .

• An RVSM -authorized aircraft eq uipped and operating with ADS -B OUT avionics

meeting the performance requirements of part 91, § 91.227 at an RVSM altitude

where ADS -B height -monitoring is provided.

E.1.5 How C an I Verify If My Airplanes Were M onitored in the Last 2 Y ears?

1. An operator that has a valid RVSM authorizatio n can check the RVSM

Approvals datab ase to determine if their last valid monitoring occu rred within

the last 2 years.

2. The following methods satisfy monitoring requirements:

• Entry of successful AGHME or other approved ground- based monitoring system

result in the U.S. RVSM Approvals datab ase.

• A report of a successful monitoring supplied by an F AA-approved, GPS -based

provider.

• Evidenc e provided through another ICAO -sponsored r egional m onitoring a gency,

such as EUROCONTROL.

Note: For North American operators, the data base can be accessed from the FAA

RVSM w ebsite un der the RVSM Documentation section or on the FAA’s North

American Approvals Registry and Monitoring Organization ( NAARMO) website

at https://www.faa.gov/air_traffic /separation_standards/naarmo/rvsm_approvals/ .

E.1.6 RVSM Height -Monitoring Plan . Operators, upon application, should submit a monitoring

plan including:

• Number and identification (registration number/se rial number) of airplanes to be

monitored.

• Expected timefram e for completion of monitoring requirements.

• Expected method for monitoring.

E-2

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Appendix F

APPENDIX F. DECISION MATRIX WHEN APPLYING FOR AN RVSM OPSPEC,

MSPEC , OR LOA

F.1 Introduction. The RVSM Authorization Matrix (or simply the “Matrix”) is a tool created

to assist operator s and the FAA in determining the typical documentation needed for

application and which RVSM Authorization Elements approval action the applicant is

seeking.

Tabl e F-1. RVSM Decision Matrix

RVSM DECISION MATRIX

AUTHORIZATION GROUP I:

RVSM AUTHORIZATION AMENDMENTS

• The following changes are considered to be administrative in nature only.

• This Group only applies in circumstances where a previously authorized RVSM operator and each

of the previously accepted RVSM Authorization Elements are remaining the same.

I. A. Examples of Requested Action/Nature of Change

1. Change in the primary business address of an RVSM- Compliant Aircraft and/or RVSM

authorization holder.

2. Change in an existing RVSM operator’s designated Responsible Person (or RVSM -Authorized

Representative or RVSM- Point of Contact (POC)).

3. Change in the registration markings of an RVSM-Compliant Aircraft being operated by an

existing RVSM authorization holder.

4. Removal of wording describing use of an RVSM-Approved Maintenance Program for

operators otherwise not having a requirement for an approved maintenance program.

5. Removal of an RVSM-Compliant Aircraft from an existing RVSM authorization that has

multiple RVSM -Compliant Aircraft listed.

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Appendix F

I. B. Applicable Steps and Information Required From RVSM Authorization Holder

1. Prior to making a request for service for an authorization amendment, each existing

authorization holder should make a positive determination as to which portions of the

previously accepted RVSM Authorization Elements the authorization holder is requesting

to change.

2. That authorization holder should then submit a written request to the appropriate Flight

Standards office that:

a. States which of the applicable administrative changes are occurring;

b. Further affirmatively states that none of the previously accepted RVSM Authorization Elements that formed the basis for the initial issuance of the affected RVSM authorization

have changed or are changing; and

c. Requests the issuance of an amendment to the existing RVSM authorization that

acknowledges the administrative change being made.

3. If the nature of the requested amendment is to change the primary business address from

one service area to another, he or she must notify, in writing, the losing (previously

responsible) FAA office of the new physical location and mailing address within

30 calendar -days following relocation. The losing office must request that the Web -based

Opera tions Safety System (WebOPSS) Help Desk move the operator’s database to the

appropriate receiving FAA office. The losing office must also notify the receiving office of

the change. The receiving office should then update and reissue the operator’s A001 tem plate

to reflect the new address, and the receiving office becomes the appropriate Flight Standards

office for processing new letters of authorization (LOA) for that operator.

4. The authorization holder should also provide such further information as requested by the

FAA to efficiently process the request.

I. C. Applicable Procedures to Be Followed by the Appropriate Flight

Standards Office

1. Review the request and supporting documentation received from the RVSM authorization

applicant to determine if it appears that an amended RVSM authorization is warranted.

2. Reissue the amended RVSM authorization that is identical to the initial RVSM authorization

in all respects other than reflecting the new amended information.

3. If the nature of the requested amendment is to change the primary business address from

one service area to another, see the additional applicable guidance in FAA Order 8900.1,

Volume 3, Cha pter 2, Section 2 , Responsibility for Part 91 Letters of Authorization (LOA).

4. If an existing RVSM authorization holder has made a written affirmation that none of the

underlying previously accepted RVSM Authorization Elements ha ve changed or will change ,

and there is no other information provided to the FAA raising any questions or concerns with

respect to the ongoing validity or applicability of those RVSM Authorization Elements, then,

subject to paragraph 5.3.4 of this AC, the appropriate Flight Standards office should issue the

requested amendment without further inspections being required.

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1/29/19 AC 91 -85B

Appendix F

AUTHORIZATION GROUP II:

RVSM AUTHORIZATION BASED ON

ONE OR MORE EXISTING APPROVED RVSM AUTHORIZATION ELEMENTS

• The following RVSM authorizations are new authorizations.

• This G roup will normally apply to a new or proposed RVSM operator that is seeking the issuance of

an RVSM authorization for an aircraft that is already an RVSM -Compliant Aircraft and/or

previously accep ted RVSM -Knowledgeable Pilots requirements with respect to its operations of that

specific aircraft.

II. A. Examples of Requested Action/Nature of Change

1. There is a change in the legal status or identity of the business entity that is the Approved

RVSM o perator, but the Responsible Person, RVSM -Authorized Representative, and/or

RVSM -POC and each of the Approved RVSM Authorization Elements are remaining the

same.

a. One example of this situation may occur where an operator is converted from an

S corporation to a limited liability company under applicable state law, but no other

changes are occurring.

b. Another example may occur where the ownership and operat ion of an aircraft is

transferred from one company to a legal affiliate, but there are no other changes occurring.

2. A new proposed RVSM operator will be using an existing RVSM -Compliant Airc raft and/or

previously accepted RVSM -Knowledgeable P ilots requir ements. Examples of this type of

situation may include:

a. An operator takes delivery of a newly manufactured air craft that is type -certif ied as

RVSM -compliant.

b. An Approved RVSM Aircraft is being operated under an RVSM authorization issued to a Title 14 of the Code of Federal Regulations ( 14 CFR ) part 135

air carrier, and the

underlying owner or a separate lessee will occasionally u se that specific aircraft and/or the

same RVSM- Knowledgeable Pilots requirements.

c. A group of underlying owners or lessees use a n RVSM -Compliant Aircraft, each

maintaining their own operational control of that aircraft pursuant to a dry lease and/or the

same RVSM- Knowledgeable Pilots requirements.

3. An existing or newly proposed Approved RVSM operator seeks an RVSM authorizat ion and

will be utilizing one or more existing Approved RVSM Authorization Elements.

a. An example may be where an existing RVSM op erator seeks to add a new proposed

RVSM -Compliant Aircraft to an existing RVSM authorization where that operator will

continue to use previously accepted RVSM- Knowledgeable Pilots requirements.

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1/29/19 AC 91 -85B

Appendix F

II. B. Applicable Steps and Information Required F rom RVSM Authorization

Applicant

1. Make a positive determination that the existing or newly proposed RVSM operator is seeking

an RVSM authorization that will utilize at least one previously Approved RVSM

Authorization Element (i.e., an existing RVSM -Compliant Aircraft and/or

RVSM -Knowledgeable Pilots requirements).

2. Submit a written request to the appropriate Flight Standards office that:

a. Provides complete documentation of an RVSM compliance program, including written information evidencing that the specific aircraft meets the requirements of an RVSM -Compliant Aircraft;

b. Further specifically states that previously accepted RVSM- Knowledgeable Pilots

requirements will be used with respect to the operation of the proposed Approved RVSM

Aircraft in RV SM airspace, as applicable;

c. Provides such additional information as necessary to evidence complianc e with new or

different RVSM -Knowledgeable Pilots requirements (or to be able to gain such

approvals); and

d. Asks for the issuance of an RVSM authorizati on that applies to the operation of the

aircraft by that proposed RVSM operator .

3. Provide such further information requested by the FAA to efficie ntly process the request.

II. C. Applicable Pr ocedures to Be Followed by the Appropriate Flight Standards

Office

1. Review the request and supporting documentation received from the RVSM authorization

applicant to determine if it appears that the requested RVSM authorization is warranted.

2. To the extent the RVSM applicant has provided wr itten documentation evidencing that the

operator will be using a previously accepted RVSM Authorization Element, and accept that

RVSM Authorization Element as a valid basis for the issuance of the new RVSM

authorization, and to the extent the applicant has presented a proposed RVSM Authorization

Element that has not been previously reviewed and accepted, conduct such additional review

and research with respect to that RVSM Authorization Element only as is required to issue the

new RVSM authorization.

3. If an RVSM applicant has made a written affirmation that one or more of the underlying

previously accepted RVSM Authorization Element s have not changed or will not change,

there is no other information provided to the FAA raising any questions or concerns wit h

respect to the ongoing validity or applicability of those RVSM Authorization Elements, and

the applicant has otherwise presented sufficient evidence of compliance with the requirements

of the remaining RVSM Authorization Elements, then, subject to paragr aph 5.3.4 , the

appropriate Flight Standards office should issue the requested amendment without further

inspections being required.

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1/29/19 AC 91 -85B

Appendix F

AUTHORIZATION GROUP III :

RVSM AUTHORIZATION NOT BASED ON

ONE OR MORE EXISTING RVSM AUTHORIZATION ELEMENTS

In the event a proposed new or existing approved RVSM operator seeks the issuance of an RVSM

authorization that will not be based on any existing RVSM Authorization Element, then neither

Authorization Group I nor II above will apply. The proposed approved RVSM operator should submit

sufficient evidence to show his or her ability to comply with each of the RVSM Authorization

Elements, and the appropriate Flight Standards office should process the request as a new and unique

request by reviewing all of the materials provided by the applicant to ensure that each of the RVSM

Authorization Elements have been met.

F-5

Advisory Circular Feedback Form

If you find an error in this AC, have recommendations for improving it, or have suggestions for

new items/subjects to be added, you may let us know by contacting the Flight Technologies

and Procedures Division at 9-AWA-AFS400-Coord@faa.gov or the Flight Standards

Directives Management Officer at 9-AWA-AFB-140-Directives@faa.gov.

Subject: AC 91-85B, Authorization of Aircraft and Operators for Flight in Reduced Vertical Separation

Minimum (RVSM) Airspace

Date: _____________________

Please check all appropriate line items:

An error (procedural or typographical) has been noted in paragraph ____________

on page _______ .

Recommend paragraph _____________ on page __________ be changed as follows:

______________________________________________________________________

______________________________________________________________________

In a future change to this AC, please cover the following subject:

(Briefly describe what you want added.)

______________________________________________________________________

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Other comments:

______________________________________________________________________

______________________________________________________________________

I would like to discuss the above. Please contact me.

Submitted by: Date: ______________________