"A notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or aeronautical hazard, the timely knowledge of which is essential for personnel related with flight operations." - ICAO Annex 15, original definition

Definition: A 1940s System Still Powering Modern Aviation

A NOTAM (Notice to Airmen) is an official message published through the Aeronautical Information Service (AIS) under the oversight of aviation authorities. While the authority governs the process, the information itself is typically created at the source — such as an airport operator or air traffic control unit — and then distributed via AIS. These notices alert pilots, dispatchers, and other operational staff to conditions that could affect flight safety.

The system has existed since the 1940s and has remained largely unchanged, continuing to serve as a cornerstone of aeronautical information management. NOTAMs follow a standardized global distribution process overseen by ICAO. Information typically originates at a local level — for example from an airport operator or ATC unit — and is submitted to the NOTAM Office (NOF). From there, it is transmitted via the Aeronautical Fixed Service (AFS) to central databases such as the European AIS Database (EAD), and then relayed through NOTAM Providers (e.g., flight planning systems like LIDO). Finally, the information reaches airline back-office operations (dispatchers) and, ultimately, the pilots who depend on it.

The terminology around NOTAMs has seen some variation over the years, including a brief period when the FAA used the wording “Notice to Air Missions.” However, the acronym NOTAM itself has remained constant, and since February 2025 the U.S. has officially reverted to “Notice to Airmen.”

Purpose: Runway Closures, Military Exercises, and More

The primary role of NOTAMs is to provide operationally significant, temporary updates that are not found in permanent publications such as Aeronautical Information Publications (AIPs).

They cover a wide range of information, such as:

• Airport operations: runway or taxiway closures, changes in lighting systems.

• Navigation aids: outages of ILS, VOR, GPS availability.

• Airspace restrictions: military exercises, VIP movements, natural disaster zones.

• Obstacles and hazards: cranes near airports, volcanic ash advisories, bird activity.

• Procedural updates: changes to approach procedures or temporary regulations.

Missing or misinterpreting a NOTAM can have serious safety consequences — a fact underscored by past incidents where overlooked notices contributed to runway incursions, closed airspace violations, or other operational hazards. This is why pilots are required to review NOTAMs as part of pre-flight planning.

A Wake‑up Call from San Francisco (2017)

On July 7, 2017, Air Canada Flight 759 nearly landed on Taxiway C at SFO—mistaking it for Runway 28R and passing within mere feet of four planes queued for takeoff. The NTSB found that the crew had “ineffective review of NOTAM information” regarding the closed parallel runway, illustrating how even a missed detail can escalate into a near catastrophe.

The NOTAM Code: A Global Aviation Language

NOTAMs follow a standardized structure to ensure consistency across countries. A typical message contains both coded fields and free text:

• Q-field: A coded summary that classifies the notice by subject, scope, and location.

• A-field: The ICAO location indicator of the relevant aerodrome or region.

• B & C fields: Start and end dates/times (validity period).

• E-field: Free-text description, written in abbreviated aviation jargon.

Example:

Note: This is a fictitious example, shown only to illustrate the standard NOTAM format.

A1234/25 NOTAMN Q) EGTT/QMRLC/IV/NBO/A/000/999/5128N00027W005 A) EGLL B) 2508200600 C) 2508231800 E) RUNWAY 09L/27R CLOSED DUE MAINTENANCE

This message indicates that London Heathrow (EGLL) runway 09L/27R will be closed for maintenance between August 20–23, 2025.

The Information Overload Problem

For every flight, pilots and dispatchers are legally required to review all relevant NOTAMs covering:

• Departure and destination airports

• Alternate airports

• Enroute airspace and navigation aids

NOTAMs are typically compiled into Pre-Flight Information Bulletins (PIBs), which for long-haul flights can easily exceed 100 pages. The result is often information overload: critical safety alerts risk being buried among dozens of routine advisories. It can feel like searching for a needle in a haystack.

This challenge has prompted a growing push across the industry to modernize how NOTAMs are managed and presented. Efforts are underway to make them more structured, machine-readable, and easier to interpret—a transformation that could significantly improve both efficiency and safety.

Now that we’ve covered the basics, the real question is: what does it look like in practice? In our next article, we will step into the briefing room and the cockpit to see how NOTAMs are actually used. We’ll look at what happens when flight crews face information overload, and how emerging innovations — from digital NOTAMs to AI-powered filtering — could reshape the way pilots and dispatchers work.