Aircraft systems and instrumentsQuestion 519 of 934

An airplane is parked overnight. The pressure falls from 29.98 inches to 29.68 inches of mercury. What does the altimeter show?

  1. An increase of about 300 feet
  2. A decrease of about 300 feet
  3. An increase of about 30 feet
  4. No change while the engine is off
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Correct answer: An increase of about 300 feet

A decrease in pressure makes the altimeter indicate an increase in altitude. Resetting the altimeter setting shows the field elevation again.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 8: Flight Instruments — Altimeter — Altimeter Operation, page 208

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026