Definition
A facility master file (FMF) is the official record maintained by an air traffic control facility that contains the standardized data, procedures, and reference information that facility uses for daily operations. It typically includes details such as airspace boundaries, sector configurations, letters of agreement, standard operating procedures, equipment data, and other facility-specific information needed by controllers.
Plain English
It is the master reference file kept by an air traffic control facility that holds all the official information about how that facility runs — its airspace, procedures, agreements with other facilities, and equipment details.
Context Anchor
Seen in FAA acronym lists, NOTAM-related material, and discussions of official aeronautical data.
Why Pilots Care
Pilots do not use the FMF directly, but the procedures and agreements documented in it shape the clearances, routings, and handoffs they receive in flight. Knowing the term helps when reading FAA publications that reference it.
Intuition Check
Do not read “facility master file” as a checklist or document a pilot normally opens in the cockpit. Here, it means an official FAA data record used behind the scenes to keep aviation facility information consistent.
Example Sentence 1
The new letter of agreement between the two centers was added to the facility master file before the procedure went into effect.
Example Sentence 2
When a navaid is relocated the FMF is updated so charts and databases stay current.