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SESK: Stuff Everyone Should Know · sesk.info/pilot-groundspeed-for-fuel

When wind is present, which speed must you use to figure flight time and fuel burn?

Groundspeed.

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  1. Indicated airspeed
  2. True airspeed
  3. Groundspeed ✔

Why: Fuel burns by the hour, and the hours depend on how fast you cover the ground. A headwind lowers groundspeed, so the trip takes longer and uses more fuel.

Huh, didn't know that: The PHAK example: 400 nautical miles at 100 knots groundspeed takes 4 hours, so 5 gallons per hour uses 20 gallons.

The dad joke
A headwind is nature's way of making a short trip feel like a long story.
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References

Answer: Groundspeed. Fuel burns by the hour, and the hours depend on how fast you cover the ground. A headwind lowers groundspeed, so the trip takes longer and uses more fuel.

  1. Pilot's Handbook of Aeronautical Knowledge FAA-H-8083-25C, Chapter 16 Navigation www.faa.gov/sites/faa.gov/files/18_phak_ch16.pdf
    you must use GS to calculate fuel consumption when wind is present.
    Checked 2026-10-09.

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