Many pilots had their first–but thankfully second-hand–exposure to the pitfalls of flight systems automation when they watched a remarkable video of an Airbus A320 performing a gear-down, nose-high flypast demonstration at the small French airport at Habsheim in 1988. At the end of the flypast, onlookers expected that the pilot would increase power and the aircraft would climb away. But it didn’t. Instead it continued straight-and-level at between 30 and 100 feet agl (both were claimed in subsequent testimony) before flying into trees just beyond the airport boundary. Three of the passengers died and there were several injuries. The aircraft was mostly destroyed in an intense fire that quickly broke out.
What happened? We may never know for certain, but the consensus among technical specialists and A320 pilots was that the aircraft was most likely under flight system autothrust control–a perfectly acceptable procedure–during the flypast, where power would be increased automatically should the airspeed fall below the speed set by the pilot, which have might have been, say, 120 knots. Manually pushing the thrust levers forward to increase power in autothrust mode would have had no effect. The crew could increase power only by deselecting autothrust.
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