A French report has found that human error and technical malfunctions caused the 2009 crash of an Air France flight from Rio to Paris that killed 228 people, a source close to the case said Wednesday.
The judicial report -- due to be presented to victims' families on Tuesday next week -- has concluded that pilot error and malfunctioning speed sensors were responsible, the source told AFP.
The French aviation safety authority BEA is due Thursday to present its final report on the June 2009 crash, a document eagerly awaited amid a row between Airbus and Air France about who ultimately bears responsibility.
The source said the separate 356-page judicial report found that speed sensors froze up and failed, but also that the "captain had failed in his duties" and "prevented the co-pilot from reacting".
The aircraft had entered a zone of turbulence two hours into the flight over the Atlantic when the autopilot suddenly disengaged, the BEA said in a preliminary report last year.
Shortly thereafter one instrument showed "a sharp fall" in airspeed and a stall warning sounded, indicating the plane was no longer being lifted by the air pushing under the wings, the BEA said.
As the two co-pilots struggled to understand what had happened the captain, who had left the cockpit to take a rest, returned but did not retake control of the plane, it said.
Air France has insisted the pilots were not to blame, saying the stall alarm had malfunctioned.
French magistrates are investigating Air France and Airbus for alleged manslaughter over the crash, notably because of the malfunctioning speed sensors, known as Pitots.
The airline replaced the Pitots, manufactured by French company Thales, on its Airbus planes with a newer model after the crash.
Victims' families have previously alleged that the involvement of big French corporations such as Airbus and Air France was influencing the affair.