French investigators say faulty sensors and inadequate pilot training caused Air France's Rio-to-Paris 447 flight to crash into the Atlantic in 2009. Their final report caps a bitter row between the airline and Airbus.
In its report, the French aviation safety authority, BEA, made 25 new safety recommendations on Thursday, including better cockpit design and better training for pilots.
Chief investigator Alain Bouillard said the two co-pilots - left at the controls while the captain rested - never understood that their plane was in a stall and were in a situation of near total loss of control in darkness during the final four minutes before the plane slammed into the ocean 1,500 kilometers off Brazil's coast.
Only a well-experienced crew with a clear understanding of the situation would have stabilized the plane in those conditions, Bouillard said.
The report also found that the co-pilots had also lacked instruments to help them identify and manage unusual situations.
This accident results from an airplane being taken out of its normal operating environment by a crew that had not understood the situation, said BEA director Jean-Paul Troadec.
“The international aeronautic community will likely focus on the crew's loss of awareness of what was going on”, Bouillard said.
The use of automatic systems on planes has improved safety overall, he explained, but when it comes down to it, safety will always be based on the capacity of the pilots and the signals which they are given, which they have to understand and react to.
It was an exceptional inquiry because of the scale of the disaster, the number of countries involved and the difficulty of locating the plane's data recorders, he said. The intense media coverage of the crash added to the pressure, Bouillard said.
One of the bereaved relatives briefed earlier on Thursday, Robert Soulas said that the pilot nosed the A330 up during the stall, instead of downward, and also gave more throttle, because of false date from speed sensors.
Soulas, who lost his daughter and son-in-law, said pilots had reacted to erroneous information, believing that their plane was diving despite dozens of stall warnings in the cockpit.
Flight 447, an Airbus A330, vanished from radar at high altitude during an Atlantic storm on June 1, 2009. All 228 on board were killed. It took days before debris was located. Robotic submarines found its black boxes 23 months later.
When the BEA issued its interim report last year, Air France insisted that its co-pilots were not to blame, claiming that the stall alarm had malfunctioned.
After the crash, the airline replaced speed sensors known as Pitots on its Airbus planes with a new model manufactured by the French company Thales.
Pilots' trade unions had also been at loggerheads with Airbus over whom or what was to blame for the airline's worst loss.
Both Air France and Airbus are under investigation for manslaughter in a separate French judicial investigation. The judge will present her findings on July 10.