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Aircraft systems and instrumentsQuestion 547 of 934

A static system blockage occurs in flight. What do the altimeter and the VSI show?

  1. The altimeter shows zero and the VSI freezes
  2. Both instruments indicate correctly
  3. The altimeter reads high and the VSI shows a descent
  4. The altimeter freezes and the VSI shows zero
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Correct answer: The altimeter freezes and the VSI shows zero

Trapped static pressure freezes the altimeter at the blockage altitude. The VSI shows a continuous zero.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 8: Flight Instruments — Blockage of the Pitot-Static System — Blocked Static System, page 213

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026