The crew of flight AF447 was in a state of almost total loss of control of the situation, according to the air accident chief leading the investigation into the downing of the Air France A330 jet in June 2009.
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French accident investigation chief Alain Bouillard explained how malfunctioning speed sensors initially triggered the disconnection of the autopilot at which point the pilots failed to react correctly as the aircraft started to stall and lose altitude.
The report stated that the so-called ‘startle effect’ played a major role in the destabilisation of the flight path and in the two pilots understanding the situation.
It judged that control inputs were likely reflexive actions that resulted from the startle effect produced by the overspeed warning. “Sometimes this effect sparks primal instinctive reaction, instant and inadequate motor responses,” the report said. “These basic reflexes may prove to be incorrect and difficult to correct under time pressure and may affect the pilot’s decision-making ability.”
“Initial and recurrent training as delivered today does not promote and test the capacity to react to the unexpected,” the report noted. “Indeed the exercises are repetitive, well known to crews and do not enable skills in resource management to be tested outside of this context,” the report stated.
“All of the effort invested in anticipation and predetermination of procedural responses does not exclude the possibility of situations with a ‘fundamental surprise’ for which the current system does not generate the indispensable capacity to react.”
Investigators said they had found it hard to understand why the crew failed to respond to the repeated stall alarms saying this could have been explained by the crew not understanding the alarm’s sound or that it was too quiet.
“The pilots stuck to what they do usually… When you lose awareness of the situation you hang on to what you’re used to doing,” said Bouillard.
The final accident report – which made 25 new safety recommendations in addition to the 16 lodged in an earlier interim report – stressed the importance of adequate training so that pilots have a better knowledge of flight mechanics in the event of an unusual situation.
It recommended that the organisation charged with overseeing European pilot training – the European Aviation Safety Agency – modify rules in order to ensure better fidelity for simulators in reproducing realistic scenarios of abnormal situations, in addition to introducing the effects of surprise and situations with a highly charged emotional factor.
“If the BEA thought that this accident was only down to the crew, we would not have made recommendations about the systems, the training, etc. Which means that this accident could no doubt have happened to other crews,” said the head of the French air accident investigation bureau Jean-Paul Troadec.