NOTAMs, Explained: Definition, Types, and Purpose of Notices to Airmen

Flight Air Traffic Control Tower, Put-in-Bay Airport (3W2), South Bass Island, Ohio, USA
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A notice to airmen is also known as a NOTAM for short. It is a brief bulletin filed with an aviation authority, such as the Federal Aviation Administration (FAA) in the U.S., to alert aircraft pilots and other personnel of important information that could affect a flight. That information might include:

  • Flight hazards, such as lasers, air shows or parachute jumps
  • Temporary flight or airspace restrictions
  • Closed or otherwise unavailable runways
  • Obstructions such as flocks of birds, large cranes, or clouds of ash or dust

Types of NOTAMs

NOTAMs are designed to convey temporary or timely information. Essentially, any abnormal conditions within the National Airspace System (NAS) trigger a NOTAM, because pilots require up-to-date details for flight planning.

Some NOTAMs are published immediately and some are published once a month. The FAA classifies NOTAMs in the U.S. into several categories, depending on the mode of transmission, reach, and intended audience.

Class I and Class II NOTAMs

Class I NOTAMs are notices published via telecommunication; Class II NOTAMs are published in the Notices to Airmen Publication (NTAP) every 28 days.

International and Domestic NOTAMs

These notices are intended for distribution in more than one country. Some international NOTAMs are published in the International section of the Notices to Airmen Publication or stored in the United States NOTAM System (USNS). International NOTAMs may be written according to ICAO format, which is a standard adopted by the International Civil Aviation Organization.

Domestic NOTAMs are normally distributed in the United States and sometimes Canada.

Civil and Military NOTAMs

Civil NOTAMs are any notices that are part of the civil NOTAM system.

Military NOTAMs, on the other hand, are notices that are primarily part of the military NOTAM system, especially those for military airports and airspace.


These are NOTAMs from the Flight Data Center and are mandatory notices. They concern information that is federal or regulatory in nature, such as information concerning changes to an instrument approach procedure. FDC NOTAMs are also issued for changes to charts or in the event of natural disasters.

Temporary Flight Restrictions (TFR) are a kind of FDC NOTAM, and so are Center Area NOTAMs. Center Area NOTAMs are notices about conditions affecting more than one airport.


In this type of notice, the letter D stands for Distant, as it is distributed not just locally but also distantly, beyond the area of responsibility of the Flight Service Station. NOTAMs (D) are further divided into NOTAMs (U), or unofficial information not yet confirmed by airport authorities, and NOTAMS (O), or other information that doesn't meet NOTAM criteria but nevertheless may be useful to flight personnel.

How to Check NOTAMs

There are a number of ways to check for NOTAMs. You can consult the Notices to Airmen Publication, which is a PDF file made available every four weeks. You can also search the FAA's PilotWeb site, which allows you to retrieve NOTAMs by airport, NOTAM number, flight path or latitude/longitude. It's up to pilots and other personnel to keep on top of essential flight information via these notices.

How to Read NOTAMs

At first, reading a NOTAM may be confusing, because it often is written in all uppercase and may contain contractions or abbreviations that may be unfamiliar to you. Once you understand the structure of a NOTAM, you may find it easier to decipher.

Most NOTAMs begin with what's known as the "accountable location," a signifier to tell you the airport location. For example, !PIT would refer to the Pittsburgh International Airport. FDC NOTAMs would begin with !FDC.

That information is followed by the NOTAM number. You can search the FAA's website for NOTAMs based on this number, which is particularly useful if one notice refers you to another. Just search the PilotWeb site for that number to see the referred NOTAM.

Following the number are keywords and conditions. This is key information that will tell you the type of NOTAM and the details relevant to your flight, whether it's a closed runway, icy conditions, changes to charts or frequencies or other important information. Lastly, the date and time the notice is in effect will be listed at the end of the transmission.

Knowing how to read NOTAMs and their contractions, plus basic aviation knowledge of navigation terminology and weight and balance definitions, will help you better understand factors that contribute to successful takeoffs, flights, and landings.