FAA Aircraft Dispatcher (ADX)Flight Planning and PerformanceMedium
A dispatcher is planning a Part 121 flag (international) operation. Compared to a domestic operation under 121.639, how does the minimum fuel reserve requirement under 121.645 differ after arriving at the alternate?
- AIt requires an additional 45 minutes at normal cruising fuel consumption, the same as domestic
- BIt requires an additional 60 minutes at normal cruising fuel consumption, more than domestic
- CIt requires an additional 30 minutes at normal cruising fuel consumption, less than domestic
- DIt requires no additional reserve fuel beyond the alternate
Show answer & explanationAnswer & explanation
Correct answer: C. It requires an additional 30 minutes at normal cruising fuel consumption, less than domestic
Under 14 CFR 121.645, flag (international) operations require fuel to fly to the destination, then the alternate, then fly for an additional 30 minutes at normal cruising fuel consumption—less than the 45-minute reserve required for domestic operations under 121.639.
Why the other options are wrong
- A. 45 minutes is the domestic reserve requirement, not the flag reserve.
- B. 60 minutes overstates the flag reserve requirement, which is only 30 minutes.
- D. A reserve is still required after reaching the alternate; it is not eliminated.
Flag Operations Fuel Reserve (121.645)
Part 121 flag (international) operations require fuel to destination, then alternate, then an additional 30 minutes at normal cruising fuel consumption—less than the domestic 45-minute reserve.
- 121.645 governs flag/international fuel reserves
- Reserve is 30 minutes at normal cruising consumption
- Domestic operations (121.639) require 45 minutes instead
Memory trick: 'Flag flies far but reserves less — thirty, not forty-five.'