requirements are discussed at some length in part 121 of the Federal
Air Regulations.G1 Specific rules for calculating the amount of reserve
fuel are given by the Air Transport Association.G2 The amount of reserve fuel given by these rules is in
excess of minimum FAR requirements but is representative of current
airline operational practices. The amount of reserve fuel specified
by reference G2 depends upon the type of aircraft and the nature of
its operation. For example, aircraft in domestic and international
operations carry different amounts of reserve fuel, as do supersonic
and subsonic transport aircraft. The reserve-fuel rules are also
different for propeller-driven aircraft equipped with reciprocating
engines and for turbine-powered aircraft.
The reserve-fuel requirements specified by reference G2 for subsonic turbine-powered aircraft employed in domestic and international operations are given as follows:
 International Operations
Flight to Alternate Airport (All Airplanes)
G1 "Certification and Operations: Domestic, Flag, and
Supplemental Air Carriers and Commercial Operators of Large
Aircraft," FAR Pt. 121, paragraph 121.195 (FAA, June 1974).
G2 Standard Method of Estimating Comparative Direct Operating Costs of Turbine Powered Transport Airplanes. (Air Transportation Association of America, December 1967).