Decoding NOTAMs.

What a NOTAM is, and why it exists

A NOTAM is a notice distributed by telecommunication that contains information on the establishment, condition or change of any aeronautical facility, service, procedure or hazard. The word historically expanded to "Notice to Airmen"; many states now read it as "Notice to Air Missions". Either way the function is the same.

The aeronautical environment is described in detail in a state's Aeronautical Information Publication (AIP). But the AIP is a stable, formally amended document. It cannot react quickly to a runway closing tonight for repairs, a navigation aid failing this afternoon, or a temporary restricted area set up for an event next week. The NOTAM system carries exactly that kind of time-critical, short-notice information.

NOTAMs broadly fall into a few categories:

• New NOTAM — introduces new information not previously notified.
• Replacement NOTAM — supersedes an earlier NOTAM; the field NOTAMR names the one it replaces.
• Cancellation NOTAM — ends an earlier NOTAM; the field NOTAMC names the one it cancels.

Checking the relevant NOTAMs is a mandatory part of pre-flight preparation. Missing one — a displaced threshold, a frequency change, a temporary obstacle — can directly compromise a flight.

The series and number

Every NOTAM is identified by a series letter followed by a number and the year, for example A0451/26 — series A, NOTAM 451, issued in 2026. The number runs sequentially within each series for the calendar year and resets at the start of the new year.

The series letter groups NOTAMs by subject or scope so that a recipient can filter for what is relevant. The exact use of each series is decided by the issuing state, but a common pattern is:

• Series for international en-route and major-aerodrome information of wide interest.
• Series for domestic aerodromes and lower-level information.
• A separate series for navigation warnings and similar.

A NOTAM that replaces or cancels another names it explicitly: NOTAMR A0430/26 means "this replaces A0430/26". Always work from the most recent NOTAM in a chain and treat the ones it replaces as superseded.

The Q-line and its fields

The first content line of a NOTAM is the qualifier line, or Q-line. It is a compact, machine-readable summary that briefing systems use to sort, filter and route NOTAMs. Its fields, separated by oblique strokes, are:

Field	Meaning
FIR	The Flight Information Region the NOTAM applies to, e.g. OEJD.
NOTAM code	A five-letter code starting with Q. Letters two and three identify the subject (what the NOTAM is about); letters four and five identify the condition (its status), e.g. QMRLC — runway (MR) closed (LC).
Traffic	Whether it concerns I (IFR), V (VFR) or IV (both).
Purpose	A combination of N (immediate attention), B (for the pre-flight bulletin), O (operationally significant) and M (miscellaneous).
Scope	A aerodrome, E en-route, W navigation warning, AE, K checklist, and so on.
Lower / Upper limit	The vertical band affected, in hundreds of feet (flight levels). Defaults are 000 and 999.
Coordinates and radius	A latitude/longitude and a radius in nautical miles defining the geographic area affected.

You do not always need to decode the Q-line by hand — its job is mostly to drive the briefing software. But understanding it explains why a NOTAM did or did not appear in your bulletin, and the subject/condition code is a quick way to grasp what a NOTAM is about before reading the text.

The A to G item format

Below the Q-line, a NOTAM is laid out as a set of lettered items. Not every item appears in every NOTAM — D, F and G in particular are used only when relevant.

A — Location

The ICAO indicator(s) of the aerodrome or FIR the NOTAM applies to, e.g. OERK.

B — Start of validity

A ten-digit date-time group (year, month, day, hour, minute) in UTC marking when the NOTAM takes effect.

C — End of validity

A ten-digit UTC date-time group for when it ends. PERM means permanent (pending an AIP amendment). The suffix EST means the end time is estimated and the NOTAM must later be cancelled or replaced.

D — Schedule

Optional. A timetable for an intermittent NOTAM — for example active only on certain days or between certain hours within the B–C window.

E — Description

The plain-text body. This is the part that actually tells you what is happening, written in standard ICAO contractions and phrasing, e.g. RWY 16L/34R CLSD.

F — Lower limit

Optional. The lower vertical limit of the affected area, used mainly for airspace and obstacle NOTAMs.

G — Upper limit

Optional. The upper vertical limit, paired with F.

A worked example:

A0451/26 NOTAMN
Q) OEJD/QMRLC/IV/NBO/A/000/999/2138N03934E005
A) OEJN B) 2606010600 C) 2606011400
E) RWY 16C/34C CLSD DUE WIP

Decoded: NOTAM 451 of 2026 (new), in the Jeddah FIR, subject "runway closed", affecting both IFR and VFR traffic, at Jeddah King Abdulaziz International. It is effective from 0600 UTC to 1400 UTC on 1 June 2026, and it says runway 16C/34C is closed due to work in progress.

Common contractions

NOTAM text uses a fixed, internationally agreed set of abbreviations so messages stay short and unambiguous. A working selection:

Contraction	Meaning
RWY / TWY	Runway / taxiway
CLSD	Closed
U/S	Unserviceable
WIP	Work in progress
OBST	Obstacle
AGL / AMSL	Above ground level / above mean sea level
ACFT	Aircraft
AVBL	Available
DUE	Due to / because of
TWR / APP	Tower / approach control
FREQ	Frequency
NAV / NDB / VOR / ILS / DME	Navigation / the named navigation aid types
PSN	Position
EXC	Except
BTN	Between
WEF	With effect from
TIL	Until
DLY	Daily
SR / SS	Sunrise / sunset

The complete list is published in ICAO Doc 8400 (PANS-ABC). When a contraction is unfamiliar, do not guess — look it up, because the difference between "available" and "unavailable" is exactly the kind of thing that gets shortened.

The Pre-Flight Information Bulletin (PIB)

You rarely read NOTAMs one at a time from the raw feed. Before a flight you receive a Pre-Flight Information Bulletin — a PIB — which is a packaged set of the NOTAMs relevant to your specific operation.

A PIB is assembled by an automated briefing system from the parameters of your planned flight: the departure, destination and alternate aerodromes, the route and FIRs crossed, the flight rules (IFR or VFR) and the time window. The system uses the Q-line fields to select only the NOTAMs that match, so a PIB is far shorter and more relevant than the full national NOTAM list.

A typical PIB is organised into sections — aerodrome NOTAMs for each airport on the plan, en-route NOTAMs for the FIRs along the route, and navigation-warning NOTAMs. Reviewing the PIB for the actual planned flight, generated close to departure, is a standard part of flight preparation. A PIB generated days earlier may miss a NOTAM issued since.

How NOTAMs relate to the AIP and AIRAC

NOTAMs do not stand alone. They sit inside a wider system of aeronautical information.

• The AIP is the permanent, authoritative reference describing a state's airspace, aerodromes, procedures and services. It is the baseline picture.
• The AIRAC cycle is the 28-day schedule on which significant, planned changes to the AIP and to charts take effect on common, internationally fixed dates, so operators can prepare in advance.
• NOTAMs carry what neither of those can deliver fast enough: temporary changes, short-notice changes, and hazards that arise between AIRAC dates.

The relationship is a hierarchy of timeliness. A long-planned change — a new procedure, a redrawn airspace boundary — goes through an AIRAC amendment to the AIP. A temporary or urgent change — a runway closed for a week, a navaid down today — goes out as a NOTAM. When a NOTAM's content becomes permanent, it is eventually absorbed into the AIP by a normal amendment and the NOTAM is cancelled. A special category, the Trigger NOTAM, is issued specifically to flag that an AIRAC amendment is coming into effect, pointing readers to the formal change.

The practical takeaway: reading the AIP, holding a current AIRAC chart database and checking the latest NOTAMs are three parts of one job, not alternatives. The exact NOTAM series structure and distribution arrangements for the Kingdom should be verified against the current AIP-KSA.