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FBO - Fixed-Based Operator, a commercial operator providing fuel, maintenance, flight training and other services at an airport.

FINAL APPROACH FIX (FAF) - The beginning of the final approach segment and the point where final segment descent may begin.

FIREPROOF - (1) With respect to materials and parts used to confine fire in a designated fire zone, means the capacity to withstand at least as well as steel in dimensions appropriate for the purpose for which they are used, the heat produced when there is a severe fire of extended duration in that zone; and (2) With respect to other materials and parts, means the capacity to withstand the heat associated with fire at least as well as steel in dimensions appropriate for the purpose for which they are used.

FIRE RESISTANT - (1) With respect to sheet or structural members means the capacity to withstand the heat associated with fire at least as well as aluminum alloy in dimensions appropriate for the purpose for which they are used; and (2) With respect to fluid-carrying lines, fluid system parts, wiring, air ducts, fittings, and powerplant controls, means the capacity to perform the intended functions under the heat and other conditions likely to occur when there is a fire at the place concerned.

FLAME RESISTANT - Not susceptible to combustion to the point of propagating a flame, beyond safe limits, after the ignition source is removed.

FLAMMABLE - With respect to a fluid or gas, means susceptible to igniting readily or to exploding.

FLASH RESISTANT - Not susceptible to burning violently when ignited.

FLIGHT CREW MEMBER - A pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.

FLIGHT PLAN - Specified information relating to the intended flight of an aircraft that is filed orally or in writing with an FSS or ATC facility.

FLIGHT TIME - (1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or (2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.

FLIGHT VISIBILITY - means the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.

FUSELAGE - An aircraft's main body structure housing the flight crew, passengers, and cargo and to which the wings, tail and in most single-engine airplanes, engine are attached.