Performance and weight and balanceQuestion 854 of 934

The main gear tire pressure is 49 psi. About what minimum speed starts dynamic hydroplaning?

  1. 63 knots
  2. 49 knots
  3. 54 knots
  4. 98 knots
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Correct answer: 63 knots

The minimum hydroplaning speed is nine times the square root of the tire pressure. Nine times 7 is 63 knots.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 11: Aircraft Performance — Water on the Runway and Dynamic Hydroplaning, page 270

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Questions last reviewed: 18 October 2026