NOTAM: Format and Decoding

A NOTAM carries the aeronautical news that cannot wait for the next edition of the AIP. A runway closed for resurfacing, an ILS out of service, a crane beside the final approach, a danger area activated for an exercise: each goes out as a short, coded message, is collected with the others for the route and aerodromes of a flight, and is read in the pre-flight briefing.

The format is set by ICAO Annex 15 and the Procedures for Air Navigation Services, Aeronautical Information Management (PANS-AIM, Doc 10066), so a NOTAM looks almost the same everywhere and EASA exams test the format itself. The United States also keeps a domestic format of its own, described below. How NOTAMs fit among the other aeronautical information products is explained in aeronautical information services.

What NOTAMs are for

ICAO defines a NOTAM as a notice distributed by telecommunication, mainly over the Aeronautical Fixed Telecommunication Network (AFTN), containing information on the establishment, condition or change of any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations. Whenever possible it is issued at least 24 hours in advance. PANS-AIM adds drafting rules: each NOTAM deals with only one subject and one condition of that subject, is as brief as possible, and can be understood without reference to another document.

The NOTAM is one channel among several, and the exam often asks which one carries what:

• information of lasting character goes into the AIP, and operationally significant permanent changes take effect on a common AIRAC date;
• a temporary change lasting three months or more, or one needing extensive text or graphics, is published as an AIP Supplement;
• advisory or administrative material goes into an Aeronautical Information Circular (AIC);
• temporary or short-notice information that matters to operations goes out by NOTAM.

Typical subjects are a closed runway or taxiway, an unserviceable navigation aid or lighting system, a changed or suspended procedure, a new obstacle near an approach path, the activation of a danger or restricted area, parachute dropping, air displays and a short-term change to a permanent area. A NOTAM is not advice. Flight planning is based on what will be available at the estimated time of use, so an ILS notified as unserviceable at the ETA is planned as unavailable, and a NOTAM withdrawing the only instrument approach can make an otherwise ideal alternate unusable (see alternate aerodromes).

The ICAO NOTAM format

An ICAO NOTAM has a header line, a qualifier line marked Q) and items A) to G). The example below is invented for illustration, but its layout is standard:

The header gives the NOTAM series, a letter, then a four-digit number, a stroke and the last two digits of the year. Each series is numbered in sequence, starting again at 0001 at 0000 UTC on 1 January. The header ends with the type of message: NOTAMN, NOTAMR or NOTAMC.

The Q-line and NOTAM codes

The Q-line is written for computers as much as for pilots. Its eight fields, separated by strokes, let briefing systems sort and select NOTAMs automatically, and some displays do not show it at all.

The NOTAM code always has five letters. The first is Q; the second and third identify the subject, and the fourth and fifth its condition. The code tables are in ICAO's PANS-ABC (Doc 8400).

A fourth and fifth letter TT mark a trigger NOTAM, described below, and the letter K in the qualifiers marks a checklist.

Items A to G: where, when and what

• A) The ICAO location indicator of the aerodrome, or of the FIR, where the facility or hazard is located.
• B) The start of validity, a ten-figure date-time group in UTC in the form year, month, day, hours, minutes.
• C) The end of validity, in the same form. EST after the group means the end time is an estimate: the NOTAM does not lapse by itself and must be replaced or canceled. PERM means the change is permanent and will be incorporated into the AIP.
• D) A schedule, when the condition applies only at certain times within the period, such as DAILY 2200-0500.
• E) The text, in plain language using ICAO abbreviations: CLSD (closed), U/S (unserviceable), WIP (works in progress), WIE (with immediate effect), BTN (between), EXC (except), ACT (active), SFC (surface) and UNL (unlimited) are among the most common.
• F) and G) The lower and upper limits of a navigation warning or an airspace reservation, such as SFC and 2500FT AMSL.

All times are UTC, so a pilot planning in local time converts once, at the start, and then works in UTC throughout.

NOTAMN, NOTAMR and NOTAMC

There are three types of NOTAM message:

• NOTAMN contains new information;
• NOTAMR replaces an earlier NOTAM, quoted in the header, as in A0461/26 NOTAMR A0457/26;
• NOTAMC cancels an earlier NOTAM, quoted in the same way, as in A0470/26 NOTAMC A0461/26.

A replaced or canceled NOTAM no longer applies, and a replacement carries a number of its own. At intervals of not more than one month a checklist of the NOTAMs currently valid is issued, itself as a NOTAM, together with a monthly printed plain-language list, so that users can confirm they hold the complete set. The old division into Class I and Class II NOTAM, telecommunication and post, is no longer used.

A trigger NOTAM announces an AIP Amendment or AIP Supplement published under the AIRAC system. Its NOTAM code ends in TT, it briefly describes the change and gives the reference of the amendment or supplement, and it comes into force on the same effective date. It remains valid for 14 days after a permanent change, or for the whole duration of a temporary one. A NOTAM is never a substitute for the AIRAC process: a change that needs charts and databases amended at the same moment everywhere waits for an AIRAC date.

SNOWTAM and ASHTAM

A SNOWTAM is a special series NOTAM, in a format of its own, reporting snow, slush, ice, frost or standing water on the movement area. Since the ICAO Global Reporting Format, applied in the EU from 12 August 2021 and worldwide from 4 November 2021, its airplane performance section gives:

• A) the aerodrome, B) the time of assessment and C) the runway;
• D) a runway condition code (RWYCC) from 6 (dry) to 0 for each third of the runway;
• E) the percent coverage, F) the depth of loose contaminant in millimeters and G) a plain-language description, each for every third;
• H) the width to which the codes apply, if less than the published width.

A SNOWTAM is valid for at most 8 hours, and a new one is issued with every new runway condition report. The old format allowed 24 hours and had a braking action code 9 (unreliable), which no longer exists; some question banks still use both. How crews turn the codes into performance is covered in wet and contaminated runways.

An ASHTAM is a special series NOTAM reporting a change in the activity of a volcano, an eruption or a volcanic ash cloud that matters to aviation. It gives the aviation color code of the volcano, from green to red, and its maximum validity is 24 hours; a new ASHTAM is issued whenever the alert level changes (see volcanic ash).

FAA NOTAMs

The FAA renamed the NOTAM "Notice to Air Missions" in 2021 and returned to "Notice to Airmen" in February 2025. The AIM describes several categories:

• NOTAM (D): navigation aids, public-use airports, runways, taxiways, lighting and obstacles, each introduced by a keyword such as RWY, TWY, APRON, AD, OBST, NAV, COM, SVC or AIRSPACE;
• FDC NOTAM: regulatory notices from the Flight Data Center, such as amendments to instrument approach procedures and charts, and temporary flight restrictions (TFRs);
• pointer NOTAM, which draws attention to another NOTAM, such as a TFR;
• special activity airspace (SAA) NOTAM, for special use airspace and other special activity airspace, such as military training routes, active outside its published times;
• military NOTAM, for military airports and navigation aids.

The domestic format is shorter than the ICAO one. In !DEN 09/047 DEN RWY 17L/35R CLSD 2609221300-2609230200, DEN is the accountability location, 09/047 the 47th NOTAM of September, then come the affected location, the keyword, the condition and the period: from 1300 UTC on 22 September 2026 to 0200 UTC the next day. The FAA's NOTAM system also provides NOTAMs in the ICAO format, so the same closure can appear in a briefing in both forms. Runway surface condition is reported in a FICON NOTAM, such as RWY 17 FICON 5/5/3, which gives a runway condition code for each third, the US counterpart of the SNOWTAM.

FDC NOTAMs deserve special attention. The FAA's terminal procedures are published every 56 days, and between editions raised minimums, unusable navigation aids and suspended procedures are issued as FDC NOTAMs. Temporary flight restrictions, under rules such as 14 CFR 91.137 (disaster areas), 91.141 (presidential movements) and 91.145 (sporting events and air shows), and security restrictions under 14 CFR 99.7 also come as FDC NOTAMs, often at short notice. Under 14 CFR 91.103 the pilot in command must become familiar with all available information concerning the flight, and NOTAMs are part of it.

Reading NOTAMs in a pre-flight briefing

A pre-flight information bulletin (PIB) is a presentation of current NOTAM information of operational significance, prepared before flight for the aerodromes and route requested. Briefing systems build it by filtering on the Q-line: location, traffic, purpose, the flight level band and the distance from the route. It does not replace the AIP, which holds the permanent information, or the meteorological documentation, which is separate (see meteorological services and briefings). ICAO Annex 2 and SERA require the pilot in command to become familiar before flight with all available information appropriate to the intended operation, and commercial operators under EASA rules carry the NOTAM and AIS briefing documentation on board and keep it for three months after the flight.

The difficulty is volume: a bulletin can hold many NOTAMs, most of them routine, and the critical one can be buried among them. On 7 July 2017, an Air Canada Airbus A320 cleared to land on runway 28R at San Francisco at night lined up instead with the parallel taxiway C, where four airliners were waiting to take off. It descended to about 100 ft above the ground and flew over the first of them before the crew began a go-around, and it reached its lowest point, about 60 ft, over the second. The parallel runway 28L was closed and its lights were off, which the NOTAMs and the ATIS reported. The NTSB found that the crew misidentified the taxiway as the runway because they were not aware of the closure, owing to their ineffective review of the NOTAM information before the flight and in the approach briefing. It cited the airline's ineffective presentation of approach procedure and NOTAM information as a contributing factor and recommended that the FAA improve how flight operations information is presented to pilots.

A practical reading method:

1. Check that the bulletin covers the departure, destination, alternates and route, for a window around each estimated time of use, and that it is current.
2. Read the aerodrome NOTAMs first: runways, approaches and navigation aids, lighting, then taxiways and services.
3. Then read the en-route items: airspace activations, restrictions and navigation warnings at the levels to be flown.
4. Translate each relevant NOTAM into a consequence for the plan (a different approach and minima, a shorter declared distance, a route change) and brief it.
5. Before departure and in flight, update the picture through the ATIS, ATC and datalink, because NOTAMs issued after the bulletin was printed are not in it.

v1prep's Flight Briefing lists NOTAMs from a stored copy of the FAA NOTAM system, refreshed about once a day. It is a study and quick-look tool, not an official briefing: a flight is planned with NOTAMs from an official source, such as the FAA's NOTAM Search, EUROCONTROL's European AIS Database or the State's AIS.

Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.