A330 Qantas pinned on Data spike effect

Three years ago mysterious in-flight upset to a Qantas Airbus A330, in which injured 119 of the 315 occupants, have resulted in improvement of flight-computer algorithms processing angle-of-attack data


In cruise at flight level 370, one of the A330's three air data inertial reference units began transmitting incorrect data spikes, including spurious information on angle of attack, which prompted the flight-control computer to command a pitch-down response.


it examined several possibilities for the cause of the failure in the Northrop Grumman air-data unit - even considering a cosmic particle strike - the inquiry could not establish a reason. It said the failure was "probably not triggered" by a software or hardware fault, environmental factors, or electromagnetic interference.




The A330's flight-control computer normally compares the angle-of-attack values received from all three air-data units, to check for validity and consistency.


This limitation of the algorithm effectively meant a spike occurring after the memorisation period expired was treated as valid data, and the flight-control system responded by suddenly pitching the aircraft nose-down.