A pilot facing faulty data and deafening alarms in an oversea thunderstorm pitched his plane sharply up instead of down as it stalled, then lost control, sending the Air France jet and all 228 people aboard to their deaths in the Atlantic Ocean in 2009.
The fatal move was part of a chain of events outlined in a report by French investigators on Thursday that could have legal consequences for plane maker Airbus and airline Air France — and could change the way pilots around the world are trained to handle planes manually.
“I don’t have control of the plane at all,” the pilot said, a minute before it crashed, according to a particularly gripping passage in the 224-page report.
The document is the result of three years of digging into what caused Air France’s deadliest-ever accident and makes sweeping recommendations for better preparing pilots worldwide to fly high-tech planes when confronted with a high-altitude crisis.
The Airbus 330 passenger jet flying from Rio de Janeiro to Paris crashed on June 1, 2009. Over-reliance on automated signals and inadequate training were repeatedly fingered as contributing to the crash, along with mounting stress in the cockpit.
Ice was the initial culprit. Ice crystals blocked speed sensors on the underbelly of the plane known as pitot tubes, the “unleashing element” in the crash, chief investigator Alain Bouillard said.
The erroneous speed readings prompted the autopilot to disengage and alarms to start sounding in the cockpit.
The pilot at the controls could not tell if the plane was stalling or going too fast, the report said.
Meanwhile, the plane’s flight director system gave conflicting information.
The flight director shows the pilot what movements of the controls he needs to make to keep the plane on a set course and altitude — but it relies on information from the pitots and other sensors. Investigators said the crew should have turned off the flight director at that point.
Instead, the pilot in control nosed the plane upward, thinking he was going too fast and the plane was in a dive, the report says. In fact, the plane was in an aerodynamic stall.
The decision to pull up so sharply instead of down was an “important element” in the cause of the crash, Bouillard said.
BEA chief Jean-Paul Troadec was careful to stress both technical and human factors in the crash. He said the pilots should have turned off automatic signal systems and flown entirely manually as soon as they realized the pitots were blocked.
William Voss, president of the Flight Safety Foundation in Alexandria, Virginia, said the pilots were unable to look past the conflicting information and understand what the aircraft was actually doing.
“Pilots a generation ago would have done that and understoond what was going on, but [the AF447 pilots] were so conditioned to rely on the automation that they were unable to do this,” he said.
“This is a problem not just limited to Air France or Airbus,” Voss said. “It’s a problem we are seeing around the world because pilots are being conditioned to treat automated processed data as truth, and not compare it with the raw information that lies underneath.”
The report could have legal implications: A separate French judicial investigation is still underway, and Air France and Airbus have been handed preliminary manslaughter charges.