Understanding NOTAMs

A NOTAM is a short, coded notice that warns you about a temporary change or hazard affecting a flight, from a closed runway to an unserviceable approach aid.

This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.

What a NOTAM is

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 timely knowledge of which is essential to people involved in flight operations. That definition, and the format, come from ICAO Annex 15 (Aeronautical Information Services), with detailed guidance in ICAO's AIS manuals. The FAA uses the same essential definition.

A word on the name. NOTAM has long stood for "Notice to Airmen". The FAA adopted the more inclusive "Notice to Air Missions" effective 2 December 2021, then reverted to "Notice to Airmen" in 2025; ICAO and many international sources continue to expand it as "Notice to Airmen". The point worth remembering is what the notice does, not which expansion is current in a given year.

The three NOTAM types

Every NOTAM is one of three types, shown by a suffix and corroborated by the EUROCONTROL OPADD guidelines:

• NOTAMN is a new NOTAM.
• NOTAMR replaces a previous NOTAM, and cancels the one it replaces.
• NOTAMC cancels a previous NOTAM.

So if you see a NOTAMR, look for the reference to the earlier NOTAM it supersedes, and read the new one rather than the old.

A worked example

A NOTAM in the ICAO format is built from a header, a qualifier line, and a set of lettered fields. Take this runway closure:

• A1234/26 NOTAMN is the NOTAM number (series A, number 1234, year 2026) and type (new).
• Q) EGTT/QMRLC/IV/NBO/A/000/999/5129N00028W005 is the Q-line, or qualifier line.
• A) EGLL is the location: London Heathrow.
• B) 2606180600 is the start of validity: 2026, June, the 18th, at 0600 UTC.
• C) 2606181800 is the end of validity: the same day at 1800 UTC.
• E) RWY 09L/27R CLOSED DUE WIP is the plain-language text: runway 09L/27R closed due to work in progress.

The Q-line packs the machine-readable qualifiers used to sort and filter NOTAMs. Reading EGTT/QMRLC/IV/NBO/A/000/999/5129N00028W005: EGTT is the London flight information region; QMRLC is the five-letter Q-code, which always starts with Q, where the subject letters MR mean runway and the condition letters LC mean closed (the Q-code structure is set out in FAA Order JO 7930.2, Appendix B); IV shows the traffic affected (IFR and VFR); NBO are purpose qualifiers; A is the scope (aerodrome); 000/999 are the lower and upper height limits as flight levels; and 5129N00028W005 is the centre coordinate with a radius of 5 nautical miles.

Two more fields appear on many NOTAMs. Field D) carries a schedule or timetable when the activity is intermittent, and fields F) and G) give the lower and upper height limits for airspace and navigation NOTAMs. Per FAA Order JO 7930.2, the date-time groups in B) and C) are UTC, C) can read PERM for a permanent change, and a time followed by EST means the end time is only estimated and the NOTAM will be replaced or cancelled later.

NOTAM overload is a real problem

NOTAMs are conventionally written in capitals using ICAO abbreviations and contractions, and they arrive in large numbers. A single pre-flight package can run to dozens of items, and a genuinely important one (a closed runway, a lowered approach minimum) can hide among routine entries about crane lights and grass cutting. This information overload is a recognised safety issue, and authorities are modernising how NOTAMs are managed and filtered, including the FAA's NOTAM modernisation work. The practical defence is disciplined reading: filter by your route, aerodromes, and altitudes, and read the high-impact categories first.

The packaged set of NOTAMs for a route or area is called a Pre-flight Information Bulletin (PIB), available from services such as the EUROCONTROL European AIS Database and the UK NATS AIS.

In Pilot EFB

Pilot EFB pulls the NOTAMs for your route and helps you work through them by aerodrome and area, so the items that matter are easier to find. NOTAMs you have already pulled stay readable with no signal, because your device holds what you have saved; getting the latest issued NOTAMs needs a connection. Pilot EFB is offline-first and is not a certified Electronic Flight Bag, so confirm against the official AIS source before you fly.