NavigationQuestion 279 of 934

An airplane flies at 120 knots airspeed. The air mass moves in the same direction at 20 knots. What is the groundspeed?

  1. 100 knots
  2. 140 knots
  3. 120 knots
  4. 160 knots
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Correct answer: 140 knots

A tailwind adds to the airspeed. 120 plus 20 gives a groundspeed of 140 knots.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 16: Navigation — Effect of Wind, page 396

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Questions last reviewed: 18 October 2026