SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ifr-vacuum-failure

A vacuum pump fails in an airplane with vacuum-driven gyros. Which instruments become unreliable?

The attitude and heading indicators.

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  1. The attitude indicator and heading indicator ✔
  2. The airspeed indicator and altimeter
  3. The vertical speed indicator and magnetic compass

Why: Many attitude and heading indicators are driven by air flowing through a vacuum system. When it fails the gyros spin down. The pitot-static instruments, compass and an electric turn coordinator keep working, which is why partial panel practice matters.

Huh, didn't know that: Many small aircraft have no warning system for vacuum failure, so you should watch the vacuum gauge.

The dad joke
My vacuum pump quit. It really sucked at its job.
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References

Answer: The attitude indicator and heading indicator. Many attitude and heading indicators are driven by air flowing through a vacuum system. When it fails the gyros spin down. The pitot-static instruments, compass and an electric turn coordinator keep working, which is why partial panel practice matters.

  1. FAA Instrument Flying Handbook (FAA-H-8083-15B) www.faa.gov/sites/faa.gov/files/pilots/FAA-H-8083-15B.pdf
    Occasionally these pumps fail, leaving the pilot with inoperative attitude and heading indicators.
    Checked 2026-10-11.
  2. FAA Instrument Flying Handbook (FAA-H-8083-15B) www.faa.gov/sites/faa.gov/files/pilots/FAA-H-8083-15B.pdf
    Many small aircraft are not equipped with a warning system for vacuum failure;
    Checked 2026-10-11.

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