FAA Commercial Pilot Airplane (CAX)Navigation and Flight PlanningHard
An aircraft is being planned for an IFR flight that requires a filed alternate. Fuel to the destination is computed at 45 gallons, fuel from the destination to the alternate is 15 gallons, and the airplane burns 10 gallons per hour at normal cruise. What minimum amount of usable fuel must be aboard at takeoff to comply with 14 CFR 91.167?
- A67.5 gallons
- B60 gallons
- C65 gallons
- D62.5 gallons
Show answer & explanationAnswer & explanation
Correct answer: A. 67.5 gallons
14 CFR 91.167 requires fuel to fly to the destination, then to the alternate, then for 45 minutes at normal cruising speed thereafter. Reserve = 10 GPH x 0.75 hr = 7.5 gallons. Total = 45 + 15 + 7.5 = 67.5 gallons.
Why the other options are wrong
- B. This omits the 45-minute IFR reserve entirely.
- C. This applies a 30-minute reserve, which is the VFR day standard, not IFR.
- D. This applies only a 15-minute reserve, well short of the requirement.
IFR Fuel Requirements (91.167)
For IFR flights requiring an alternate, the aircraft must carry enough fuel to fly to the destination, then to the alternate airport, then for 45 minutes at normal cruising speed.
- Applies when an alternate is required under 91.169
- Reserve is 45 minutes at normal cruise, same time as night VFR but a different rule
- If no alternate is required, only destination fuel plus 45-minute reserve applies
Memory trick: 'Destination, Diversion, Forty-five' — the IFR fuel triad.