Air France Flight 447: Black Boxes Indicate Pilot Error Caused Accident

The plane apparently encountered heavy icing, causing sensors to malfunction.

ByABC News
May 24, 2011, 4:08 PM

May 24, 2011 -- Nearly two years after Air France flight 447 plunged into the Atlantic Ocean, killing 228 people, the plane's black boxes, discovered early last month, reveal the pilots' actions may have ultimately caused the accident.

The aircraft's data and voice recorder were found with wreckage from the airliner more than 13,000 feet below the ocean's surface.

Flight 447 had taken off from Brazil and was bound for Paris when, at 35,000 feet and nearly four hours into the flight, the plane apparently encountered heavy icing. The icing caused the speed sensors to malfunction, which meant the on-board computers were receiving faulty and confusing speed readings.

With the computers unable to process the confusing speed information, the autopilot shut down, leaving the jumbo jet suddenly in the hands of the cockpit crew.

ABC news has confirmed that when the emergency began, the captain was out of the cockpit on a break. With alarms likely sounding, his crewmates, possibly confused, tried to diagnose the problem. A German newspaper reports the captain rushed back into the cockpit shouting commands at his two co-pilots.

William Voss, President and CEO of the Flight Safety Foundation, told ABC News that the pilots could have gotten sidetracked trying to deal with the emergency.

ABC News has learned the jumbo jet, an Airbus A330 was still flyable, but the pilots apparently failed to do what was necessary to keep the jet in the air. They may have flown too slowly, causing the plane to stall and tumble out of the sky. The Wall Street Journal first reported that the crew failed to failed to fly the plane properly.

"In general, up at altitude, you don't have a lot of extra room," said Voss, "because the engines are producing just enough thrust to keep you there and you have a fairly small margin for where the nose can be tilted to maintain altitude."

The pilots apparently had not been trained to handle precisely this kind of emergency.

Voss said even as planes get more complicated and automated, it's important to put the emphasis back on making emergency procedures simple, and not to let technology interfere with the basics of flying an airplane.

Airbus, Air France and French investigators have refused to comment publically on the information from the black boxes.