What is a NOTAM?
A NOTAM is a short, time-critical notice telling pilots about a change to the aviation system that they could not reasonably have known from their charts or the AIP. Runway closures, unserviceable navaids, cranes, frequency changes, restricted airspace — all of these arrive as NOTAMs.
What NOTAM stands for
Notice to Air Missions — formerly "Notice to Airmen." The name changed in 2021 to use gender-neutral language, but the format stayed exactly the same. Every NOTAM is issued by an Aeronautical Information Service (AIS) and distributed through national and international channels so flight crews can review it before departure.
Why NOTAMs exist
Charts and the AIP are updated on fixed cycles, but the real world changes faster. A runway can close overnight, a crane can appear near an approach path, or a navaid can fail. NOTAMs are the mechanism for getting those changes into pilots' hands quickly, without waiting for the next chart revision.
The trade-off is density. Because NOTAMs were designed for old teleprinter networks, they are written in all capitals with contractions. A single route can generate dozens or even hundreds of them, which is why the briefing process is as much about filtering as it is about reading.
The main types of NOTAM
New NOTAM
A brand-new notice. This is the most common type.
Replaces
Updates an earlier NOTAM. The old one is no longer valid.
Cancels
Withdraws an earlier NOTAM before its original end date.
Snowtam
Runway surface condition report: contamination, braking action, and depth.
Ashtam
Volcanic ash advisory: location, flight levels, and movement of an ash cloud.
FDC NOTAM
US regulatory NOTAMs covering procedure changes, airspace amendments, and TFRs.
What a NOTAM tells you
Despite the cryptic layout, most NOTAMs reduce to a handful of facts:
Closed runway
RWY 09L/27R CLSD DUE WIP — runway closed due to work in progress.
Unserviceable navaid
ILS RWY 27R U/S — the ILS for runway 27 right is out of service.
Temporary schedule
DLY 2100-0300 — active only between 21:00Z and 03:00Z each day.
Procedure change
CTAF FREQ CHANGED TO 122.800 — the Common Traffic Advisory Frequency has moved.
How pilots actually use them
Before a flight, the crew collects every NOTAM for the departure, destination, alternates, and en-route FIRs. The goal is not to memorise every line — it is to spot the handful that change the plan: a closed runway that affects the alternate, a navaid failure that removes an approach option, a restricted area that cuts across the route.
That filtering is where most of the risk lives. A critical frequency change can be buried in a pack of routine crane notices. Good briefing tools surface the ones that match your route and time, but the pilot still makes the operational decision.
Common NOTAM traps
- Valid is not active. A NOTAM can be valid for weeks while its D) schedule means it only applies at night. Always check the schedule against your actual off-blocks time.
- Everything is UTC. Every time in a NOTAM is Zulu. Local time zones are a common source of mistakes.
- Volume hides risk. The dangerous item is rarely the longest one; it is the short line about a frequency change or a closed taxiway that everyone else skimmed past.
- Crew responsibility never disappears. A decoder or briefing service makes NOTAMs readable, but the flight crew remains responsible for checking official sources and deciding what the notice means for the flight.
Decode a NOTAM instantly
Paste any NOTAM into our free decoder and read it in plain English — or let Dispatch Brief turn your whole route pack into a concise, spoken briefing.
Frequently asked
What does NOTAM stand for?
Notice to Air Missions. It is a short, time-critical message telling pilots about something they could not reasonably have known from charts or the AIP — a closed runway, an unserviceable navaid, a crane, restricted airspace, or a frequency change.
Who issues NOTAMs?
National aviation authorities and aerodrome operators issue NOTAMs through their Aeronautical Information Services (AIS). In the US, FAA NOTAMs are distributed through the NOTAM Search system; in Europe, they flow through the European AIS Database (EAD) and national providers.
What is the difference between a NOTAM, a SNOWTAM, and an ASHTAM?
A NOTAM covers general changes. A SNOWTAM reports runway surface conditions such as snow, slush, or ice. An ASHTAM warns of volcanic ash. An FDC NOTAM in the US carries regulatory information such as amendments to procedures or airspace.
Are NOTAMs mandatory to read?
Yes. Flight crews are required to review all relevant NOTAMs before flight. They are part of the official pre-flight briefing and remain the pilot's responsibility even when using a decoder or briefing service.
Why are NOTAMs written in all capitals with contractions?
The format was designed for low-bandwidth teleprinter networks. Capital letters and contractions keep messages short and unambiguous. Today the same format is used worldwide so every pilot and system reads the same message.
Keep reading
For training and situational awareness only. Always cross-check with your official briefing source before flight.