The fuel reserve requirements for turbine-powered Part 121 carriers operating to/from outside of the 48-contiguous US (e.g., from San Juan) are different from the basic requirements listed above.
- Instead of a 45 minute reserve, the en route reserve is calculated as 10% of the en route time (may be reduced with special operational specifications)
- Time to reach the most distant alternate must be added
- An additional 30 minutes of holding time must be added (sometimes called an "international reserve")
- Additional fuel for contingencies must be added; such as fuel to account for winds, traffic delays, a possible missed approach, and "any other conditions" which may delay the arrival of the aircraft
- Then additional fuel considerations may be specified by company procedures and/or requested by the Captain
These requirements are spelled out in 121.645(b) and 121.647:
121.645 Fuel supply: Turbine-engine powered airplanes, other than turbo propeller: Flag and supplemental operations
(b) For any certificate holder conducting flag or supplemental operations outside the 48 contiguous United States and the District of Columbia, unless authorized by the Administrator in the operations specifications, no person may release for flight or takeoff a turbine-engine powered airplane (other than a turbo-propeller powered airplane) unless, considering wind and other weather conditions expected, it has enough fuel—
(1) To fly to and land at the airport to which it is released;
(2) After that, to fly for a period of 10 percent of the total time required to fly from the airport of departure to, and land at, the airport to which it was released;
(3) After that, to fly to and land at the most distant alternate airport specified in the flight release, if an alternate is required; and
(4) After that, to fly for 30 minutes at holding speed at 1,500 feet above the alternate airport (or the destination airport if no alternate is required) under standard temperature conditions.
121.647 Factors for computing fuel required.
Each person computing fuel required for the purposes of this subpart shall consider the following:
(a) Wind and other weather conditions forecast.
(b) Anticipated traffic delays.
(c) One instrument approach and possible missed approach at destination.
(d) Any other conditions that may delay landing of the aircraft.