NOTAM

A NOTAM — Notice to Air Missions — is an official aeronautical notice containing time-sensitive information essential to flight safety that has not yet been incorporated into aeronautical charts, publications, or other permanent documentation. NOTAMs inform pilots, dispatchers, and other aviation users about hazards, temporary airspace restrictions, closed runways and taxiways, inoperative navigation aids, construction activities near runways, laser display events, presidential travel restrictions, and dozens of other conditions that affect the safety of a specific flight at a specific time.

What Is a NOTAM?

NOTAMs are issued by aviation authorities and airport operators through a global network that connects to the ICAO NOTAM system, allowing any pilot anywhere in the world to receive notices affecting their planned route. In the United States, the FAA's NOTAM system processes and distributes notices 24 hours a day. A NOTAM has a standardized structure: it begins with an identification number, specifies the type of NOTAM (new, replace, cancel), identifies the affected aerodrome or airspace using ICAO location identifiers, specifies the subject and condition codes that describe what is affected and how, and includes effective dates and times in UTC. The NOTAM code system was designed to be readable by pilots fluent in the abbreviation language, though the result is often described as nearly impenetrable to anyone outside aviation.

How It Works in Practice

Pilots and dispatchers must review all applicable NOTAMs during preflight planning for every flight. This means checking NOTAMs for the departure airport, the destination airport, the alternate airport, and all en-route waypoints and navigational aids. On a typical commercial flight, a dispatcher may review dozens of NOTAMs, filtering for those that affect the proposed routing, cruising altitude, or airport usability. A NOTAM indicating that the ILS for the destination runway is out of service may force a change in alternate airport selection if the forecast weather is near minimums. A NOTAM indicating a Temporary Flight Restriction (TFR) due to a presidential movement may require a routing change entirely. Presidential TFRs in the United States create a 30-nautical-mile outer ring and a 10-nautical-mile inner ring of restricted airspace wherever the president travels, managed by the Secret Service and the FAA.

Why It Matters

NOTAM failures have contributed to accidents and incidents. The 2006 Comair Flight 5191 crash in Lexington, Kentucky — where the crew attempted to take off from a runway that was too short for their aircraft — occurred partly because the NOTAM indicating that the main runway was closed for construction and that runway 26 was the active departure runway was not clearly communicated to the crew during an abnormal night departure. The accident killed 49 of 50 people aboard. This accident and others drove the FAA to revise NOTAM presentation, moving toward the more human-readable NOTAM format introduced in 2021, which replaced the compressed code-heavy format with plain English sentences, significantly reducing the cognitive load on pilots conducting preflight planning under time pressure.

Key Facts and Figures

• The FAA processes over 100,000 active NOTAMs in the national airspace system at any given time.
• The 2021 NOTAM reform introduced plain-language NOTAMs in the US, replacing compressed codes like "!ORD ORD RWY 14R/32L CLSD" with readable sentences.
• Presidential TFRs are defined under FAR 91.141 and are among the most broadly affecting NOTAMs in terms of geographic scope.
• NOTAMs are classified by type: NOTAM (D) for distant NOTAMs distributed throughout the national system, FDC NOTAMs for regulatory amendments, and POINTER NOTAMs for cross-referencing.
• A single NOTAM can affect a single taxiway light or an entire airspace sector of thousands of square miles.
• ICAO standardized the NOTAM format in Annex 15 to the Chicago Convention, ensuring global interoperability.

Related Concepts

ATC, Airspace Classification, TFR, ILS, Preflight Planning