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Computer-Related Incidents with Commercial Aircraft

Comair, Embraer Brasilia turboprop, Primary Flight Display information loss, 19 March 2001

19 March 2001

Synopsis In Flight International, 11-17 Mar 2003, p12, David Learmount reported on the loss of attitude information on the electronic attitude direction indicators (EADI) in a temporary loss-of-control incident due to icing with an Embraer Brasilia commuter turboprop operated by Comair. The incident was investigated by the US National Transportation Safety Board.

The aircraft was cruising at 17,000 ft when it encountered icing conditions. It oscillated violently in roll (110 degrees left, 130 degrees right, then a 360 degree roll to the right -yes, that's a full rotation) and pitched 60 degrees nose down. During this manoeuvre, the EADIs, which present crucial information to the pilots, "blacked out". The attitude indicator gives perhaps the most crucial control information available to pilots in instrument flight conditions. They recovered at 10,000 ft altitude when the aircraft emerged into visual flight conditions below the cloud. They pulled 3.6g to recover from the descent,

I recounted this incident, with discussion, in an article Failure of aircraft electronic displays at a critical moment in the Risks Digest, Volume 22 Number 65, 28 March, 2003.