Originally Posted by
FGD135
Don't know about the data protocol(s), edmundronald, but can tell you that both Boeing and Airbus flight computers act on unfiltered data.
Take the incident of QF72, for example. Airbus A330, 7 October, 2008. During cruise, the angle of attack data suddenly indicated a very high value. The computer suddenly thought the plane was stalled and pushed the nose down. Passengers and Flight Attendants were thrown into the ceiling and there were several serious injuries.
There was a single spike in the data. That the readings immediately before were normal was not checked for. That the aircraft could have pitched from normal cruise AoA up to and beyond the stalling AoA instantly was not checked for. And if that wasn't amateurish enough, there was then the flight computers, thinking that a sudden pitch down whilst going at 450 knots was a good idea.
There was not a single spike..from the report
Although the FCPC algorithm for processing AOA data was generally very effective, it could not manage a scenario where there were multiple spikes in AOA from one ADIRU that were 1.2 seconds apart. The occurrence was the only known example where this design limitation led to a pitch-down command in over 28 million flight hours on A330/A340 aircraft, and the aircraft manufacturer subsequently redesigned the AOA algorithm to prevent the same type of accident from occurring again.