Final report on Air France crash expected
More than 200 people died in the June 1, 2009, crash of the Brazil-to-France flight.
It took four searches over the course of nearly two years to locate the bulk of the wreckage and the majority of the bodies in a mountain range deep under the ocean.
The aircraft's voice recorder and flight data recorder were found on the ocean floor in May 2011 after an extensive search using miniature submersible vehicles.
France's Bureau of Investigation and Analysis said the data indicated that Flight 447 crashed because the aircraft's speed sensors gave invalid readings.
Last year's report from the bureau said the airplane climbed to 38,000 feet when "the stall warning was triggered and the airplane stalled." It then descended, crashing into the Atlantic. The descent lasted three minutes and 30 seconds, and the engines remained operational, the report said.
Studies of the debris and bodies found soon after the crash led the French agency to conclude the plane hit the water belly first, essentially intact. Oxygen masks were not deployed, indicating that the cabin did not depressurize, the bureau said in a 2009 report.
Flight 447 was passing through an area prone to volatile and dangerous weather known as the Inter-tropical Convergence Zone when it went down. The zone is a belt of low pressure that wraps around the planet. Clouds and storms form along it because it is literally where the winds of the world's hemispheres meet.
The Bureau of Investigation and Analysis' previous report also raised questions about the training of the pilots on that flight.
The recorders revealed the pilots had failed to discuss repeated stall warnings and "had received no high altitude training" to deal with the situation, the bureau said.
The pilots got conflicting air speed readings in the minutes leading up to the crash and, after the stall, responded by pointing the nose upward, rather than downward, to recover.
They failed to regain control of the aircraft, and no announcement was made to the passengers before it plummeted from the sky.