Human error and technical failures were responsible for the crash of the Air France flight 447 into the Atlantic Ocean as it travelled from Paris from Rio de Janeiro in June 2009 killing 228 passengers.
According to the final report by French aviation investigator BEA, a speed sensor aboard the airline's Airbus A330, called a pitot tube, malfunctioned following the ice blockage at high-altitude, and delivered inaccurate data to the cockpit during the aircraft's flight through a thunderstorm.
The flight management computer disengaged the autopilot due to the disproportionate airspeed data it was receiving and shifted the controls back to the pilots.
Due to the heavy turbulence, the pilots failed to properly analyse the severity of the problem and the plane started descending and entered a deep stall.
BEA report revealed that the pilots lacked the correct training to react to a surprise scenario of malfunctioning of aircraft's speed sensors and recommended the pilots should be better trained to manually fly commercial aircraft at high altitudes and called for strict plane certification protocols.
The report said that the aeroplane went into a sustained stall, signalled by the stall warning and strong buffet.
"Despite these persistent symptoms, the crew never understood that they were stalling and consequently never applied a recovery manoeuvre," the report added.
BEA alos said that the two pilots not flying (PNF) had failed to note the inappropriate inputs by the pilot flying on the flight controls at high altitude.
The report also recommended an enhanced cockpit instrument layout to assist crews in order to better identify and handle unusual situations and provision of enhanced simulators.
Currently, French magistrates are investigating both Air France and Airbus for the alleged homicide related to the crash.
Image: recovering the wreckage of the Air France flight 447. Image: courtesy of Pawel Kierzkowski.