Friday, September 30, 2005

RISKS: Software hijacks jet airliner ... again?

Via RISKS Digest.

The Australian (17 Sep 2005) has a chilling story about the pilots of a Malaysian Airlines 777 flying from Perth to Kuala Lumpur last month battling to regain control after an "unknown computer error" caused the aircraft to pitch violently, and brought it close to stalling.

An Australian Transport Safety Bureau report released yesterday reveals the pilot in command disconnected the autopilot and lowered the plane's nose to prevent a stall, after incorrect data from a supposedly fail-safe device caused the plane to pitch up and climb 3000ft, cutting its indicated air speed from 500kmh to 292kmh, activating a stall warning and a "stickshaker". [A stickshaker vibrates the aircraft's controls to warn the piot when he is approaching stall speed ... which, you know, means the plane is about to fall out of the air.]

The system refused to give up control, however. It increased the power on the automatic throttle, forcing the pilot to counter by pushing the thrust levers to the idle position. The aircraft immediately pitched up again, and climbed 2000ft.

The pilot turned back to Perth under manual control. When he kicked in the two autopilot systems, the plane banked to the right, and the nose pitched down.

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