When the vacuum system fails, the artificial horizon slowly goes back into it's non-vacuumed position. I found no picture on that but it's a quite high angle of bank that is indicated.

Has there ever been an accident because of the failure of the vacuum system? In flightsim, I always needed some time to realize the AH is no more working and adjusted my bank to "fly straight" again.

  • 3
    $\begingroup$ On my first cross-country flight during training my vacuum pump failed (VFR) and the first thing I noticed was that the artificial horizon was a little low, but the larger telling sign was that the gyro compass was lagging heavily. A quick look at the vac gauge confirmed and by the time I turned around it was a complete failure. I landed and the school confirmed the pump was bad, but gave me the option to continue, which I declined (the instruments were not required). $\endgroup$
    – Ron Beyer
    May 25, 2017 at 14:13
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    $\begingroup$ t does not qualify as vacuum failure, because airliner IRUs use solid-state (vibrating or laser) gyros, but this West Atlantic Sweden CRJ2 crashed on Jan 8th 2016 due to attitude indicator failure—and poor design, because the system had enough information to declare itself failed, but didn't. $\endgroup$
    – Jan Hudec
    May 25, 2017 at 17:58

1 Answer 1


There have been many accidents because the vacuum system failed; AOPA has a good article that discusses some of them, and see this NTSB preliminary report for an example.

As for accidents caused because the pilot didn't notice, that's a more difficult question: if the pilot didn't survive then there's no definitive way to know what happened and what he experienced. It's always possible that the pilot was fully aware that the vacuum system failed, he just wasn't good enough at partial panel flying to keep the aircraft under control.


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