Definition
A NOTAM is a time-critical notice issued by aviation authorities to alert pilots and other flight personnel of conditions affecting the National Airspace System that are not known far enough in advance to be published on charts or in standard flight publications. NOTAMs cover items such as runway closures, navigation aid outages, taxiway construction, airspace restrictions, obstacles, unlighted obstructions, and changes to airport services or procedures. Pilots are required to review relevant NOTAMs as part of preflight planning under 14 CFR 91.103.
Plain English
A NOTAM is an official short-notice alert telling pilots about something that has changed at an airport, along a route, or in the airspace — closed runways, broken lights, restricted areas, and so on — so they can plan around it before they fly.
Context Anchor
Pilots check NOTAMs during preflight planning, usually as part of a weather briefing or flight-planning review before departure.
Derivation
The name is a plain description of what it is: a notice issued to airmen (the historical term for pilots and flight crew). The phrasing dates from when most aviation regulations referred to flight personnel collectively as airmen. The FAA has been transitioning the expansion to 'Notice to Air Missions' to reflect modern usage, but the acronym NOTAM is unchanged.
Why Pilots Care
Pilots must review NOTAMs before every flight to avoid hazards such as closed runways, temporary flight restrictions, or equipment outages that could compromise safety.
Analogy
A NOTAM is like a road-closure alert before a drive. The road may still appear on the map, but the current notice tells you what has changed right now.
Intuition Check
A NOTAM is not just a general announcement. It is official flight information that may directly affect whether, where, or how you can safely operate.
Example Sentence 1
During preflight, the pilot checked NOTAMs and found that the primary runway at the destination was closed for maintenance until 1800 local.
Example Sentence 2
A NOTAM warned of temporary flight restrictions in the area due to a presidential movement.