FAA Instrument Flight Instructor (FII)Instrument RegulationsEasy
A pilot plans an IFR flight in a nonturbine airplane and determines that an alternate airport is required under 91.169. The estimated flight time to the destination airport is 2 hours 10 minutes, and the estimated flight time from the destination to the filed alternate is 40 minutes. Under 14 CFR 91.167, what is the minimum total fuel supply (expressed as flight time) the aircraft must carry at takeoff?
- A2 hours 10 minutes
- B3 hours 50 minutes
- C2 hours 50 minutes
- D3 hours 35 minutes
Show answer & explanationAnswer & explanation
Correct answer: D. 3 hours 35 minutes
91.167 requires enough fuel to fly to the destination (2:10), then to the alternate (0:40), then fly for 45 additional minutes at normal cruising speed. 2:10 + 0:40 = 2:50, plus the 0:45 reserve = 3:35 total.
Why the other options are wrong
- A. Only accounts for the leg to the destination, ignoring the alternate leg and reserve.
- B. Overstates the required fuel beyond the regulatory minimum.
- C. Adds the alternate leg but omits the required 45-minute reserve.
91.167 IFR Fuel Requirements
When an alternate is required, IFR fuel planning must cover the flight to the destination, then to the alternate, then 45 minutes of additional flight at normal cruising speed (nonturbine aircraft).
- Applies when an alternate is required under 91.169(a).
- Reserve is 45 minutes for nonturbine, 30 minutes for turbine.
- If no alternate is required, only fuel to destination plus reserve is needed.
Memory trick: 'Destination, Divert, then Delay 45' keeps you legal and fueled.