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Aircraft systems and instrumentsQuestion 563 of 934

How much error can the Earth's rotation cause in a heading indicator?

  1. Up to 1° per hour
  2. Up to 45° per hour
  3. Up to 90° per day
  4. Up to 15° per hour
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Correct answer: Up to 15° per hour

The Earth rotates 15° in 1 hour. Precession from friction adds to the drift.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 8: Flight Instruments — Gyroscopic Flight Instruments — Heading Indicator, page 222

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026