FOR THE past two years, those final few minutes before Air France flight 447 crashed into the Atlantic en route from Rio de Janeiro to Paris have presented experts with one of the most baffling mysteries in modern aviation.
The breakthrough finally came last month, when search teams managed to recover both of the aircraft’s black boxes at an ocean depth of 3,900m (12,800ft) along with the body of the aircraft and the remains of some of the 228 victims. Three young Irishwomen returning from a holiday in Brazil were among the dead.
Yesterday, France’s air accident investigation unit, the BEA, set out preliminary impressions gleaned from the cockpit voice and data recorders of the circumstances on board as the Airbus A330 flew through stormy weather on June 1st, 2009.
It reveals that the crew scrambled to avert disaster as the passenger jet lost speed just a few hours into the flight, before it stalled and began a 3½ minute descent, belly-first, to the ocean surface.
According to the BEA, one of the pilots called the cabin crew two hours and six minutes into the flight to tell them that “in two minutes we should enter an area where it’ll move about a bit more than at the moment, you should watch out”, adding: “I’ll call you back as soon as we’re out of it.”
The aircraft crashed eight minutes later.
The crew had tried to climb above an approaching storm cloud, a common obstacle on the route, but were prevented from doing so because the air temperature wasn’t cold enough to ascend to that level.
With the flight captain resting and the two co-pilots at the controls, the auto-pilots disengaged four minutes after the turbulence warning and the crew took manual control. “I have the controls,” one of the pilots said.
After some time, the pilots noticed that the speed sensors were giving contradictory readings. They responded by pulling up the nose of the aircraft, recordings show. A stall warning sounded in the cockpit, signalling that the plane’s aerodynamics were not generating enough lift.
According to the BEA, the co-pilots continued to increase the angle of climb, rising rapidly from 35,000ft to 37,500ft.
When a third stall warning sounded, they continued to pull back on the controls with the engines set to full thrust and rose to about 38,000ft, where the jet stalled.
Less than two minutes after the autopilot went offline, the chief pilot, Marc Dubois, returned to the cockpit, and the conversation shows he was with his colleagues during the remainder of the flight. It’s routine for pilots to take a break away from the cockpit on long-haul flights, Air France has said.
With the aircraft’s nose still pointed up, the jet began falling at about 10,000ft a minute, rolling left and right. The final recordings show the aircraft had fallen back to a speed of about 198km/h (123 miles per hour), the BEA said.
“These are so far just observations, not an understanding of the events,” said the BEA’s director, Jean-Paul Troadec.
An interim report with preliminary conclusions is due in mid-July.
