A NOTAM is an abbreviation for a Notice to Airmen. NOTAMs are issued by the FAA for many different reasons, but mostly to inform pilots of changes to airports, airways and local procedures that affect the safety of flight.
There are many types of NOTAMs, including international, domestic, military and civilian. They can be mandatory or advisory in nature. Private pilots and commercial pilots in the United States should concern themselves with the following NOTAM types:
- NOTAM(D): NOTAMs that are distributed to an area beyond that of the local airport area are considered NOTAM(D) (think 'D' for Distant). These are distributed beyond the area of the flight service station and are divided into two groups, (U) NOTAMs and (O) NOTAMs. (U) NOTAMs are those that come from an unofficial source and aren't verified by the airport manager. (O) NOTAMs are notices to airmen that don't meet the standards of a typical NOTAM but can be beneficial to pilots.
- NOTAM(L): The NOTAM(L) category doesn't exist any longer for civilian pilots. This type of NOTAM is still used in the military. A NOTAM(L) is a voice NOTAM, confined to the local airport area, and is typically broadcast over the radio or telephone. NOTAM(L)s that were used before have been reclassified as NOTAM(D)s.
- GPS NOTAMs: GPS NOTAMs are issued for areas of service problems or outages.
- FDC NOTAMs Flight Data Center NOTAMs are mandatory and require compliance. These include instrument approach procedure and airway changes or safety hazards involved with either. Temporary Flight Restrictions (TFRs) are considered FDC NOTAMs. TFRs are issued for necessary and immediate airspace closures, such as the airspace around the White House or the temporary closure of airspace around live events such as the Olympics.
- Center Area NOTAMs: A Center Area NOTAM is actually an FDC NOTAM issued for a large area. It's distributed by the Air Route Traffic Control Center (ARTCC) and covers multiple airports. Airway restrictions, laser activity and TFRs are examples of Center Area NOTAMs.
- Class I NOTAMs: Standard NOTAMs released via telecommunication.
- Class II NOTAMs or Published NOTAMs: Published NOTAMS are not distributed via telecommunication. Instead, they are published in a Notice to Airmen Publication (NTAP), updated every 28 days.
- International NOTAMs: International NOTAMs are distributed to more than one country. International NOTAMS are published in ICAO format and stored in the International section of the NTAP. International NOTAMS aren't offered in a regular flight service briefing; they must be specifically requested by the pilot.
- Domestic NOTAMs: Include NOTAMS from the United States and sometimes Canada, and are completed in FAA format instead of ICAO.
- There is also a distinction between civil and military NOTAMs. Military NOTAMs include safety concerns specific to military airfield and military operations that aren't otherwise covered under the civil NOTAM system.