Reading Capt. Richard De Crepisgny’s account of the QF32 emergency I noted with interest his surprise in the final approach when the aircraft stall warnings sounded, although the same alarms had been silent when the landing had been ‘dry run’ at 4000 feet (p261 of QF32).
Captain De Crepisgny’s alarm at receiving speed and stall warnings on final is certainly understandable, but I think that such a surprise was almost predictable given the manner in which Airbus designs it’s flight control software. As I’ve noted elsewhere in this blog Airbus designers have a Weltanschauung that having designed their software around how the believe the aircraft should be operated that this is the only way it will be operated.
As control checking, a military technique to evaluate post battle damage to an aircraft, does not fit within the Airbus Weltanschauung I’m un-surprised that there would be such a difference. Undoubtedly when the over due final report of QF32 is released we’ll find that there is some specific parameter used in the software that has made the software mode sensitive.
My personal view is that conducting such a dry run was a critical success factor in the subsequent recovery of QF32 to Changi. Despite all the software bells and whistles when an aircraft has received such a massive insult as had QF32 it’s the learning and imagination that a human aircrew brought to the table that saved the aircraft. In some ways the actions Capt. De Crepisgny and his crew reflect a similar attitude of risk versus return as the early space flight pioneers.