FAA Instrument Rating Airplane (IRA)Regulations and CurrencyMedium
A pilot flying a piston airplane under IFR calculates 40 minutes of flight time to the destination and 30 minutes from there to the filed alternate, with a fuel burn rate of 12 gallons per hour. Applying 14 CFR 91.167, what minimum amount of usable fuel must be aboard at takeoff?
- A14 gallons
- B18 gallons
- C23 gallons
- D26 gallons
Show answer & explanationAnswer & explanation
Correct answer: C. 23 gallons
91.167 requires fuel to fly to the destination, then to the alternate, then for 45 minutes at normal cruising speed. Total time = 40 + 30 + 45 = 115 minutes = 1.9167 hours. At 12 gal/hr, required fuel = 1.9167 × 12 = 23 gallons.
Why the other options are wrong
- A. This only accounts for the destination leg plus a partial reserve.
- B. This omits the required 45-minute reserve.
- D. This overstates the requirement by adding extra unneeded time.
IFR Fuel Reserve — 91.167
IFR flights must carry enough fuel to reach the destination, then the alternate (if required), then fly 45 minutes at normal cruising speed (piston aircraft).
- Applies fuel math to destination + alternate + 45-minute reserve
- 45 minutes applies to reciprocating engines; 30 minutes to turbine (91.167(a)(3))
- No alternate needed reserve applies if none is required by 91.169
Memory trick: 'Destination, Diversion, then Forty-Five'