Air France Flight 447 Crash Probe Shows Confused Crew, Misread Instruments

By Laurence Frost - Oct 6, 2011 6:01 AM GMT+0700
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Salvage teams work to retrieve debris from the wreckage of Air France flight 447 off the coast of Brazil on June 8, 2009. Source: Forca Aerea Brasileira via Bloomberg

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Journalists report the first wreckage pieces and objects of the Air France flight AF447, lost in midflight over the Atlantic ocean June 1st 2009. Photographer: Mauricio Lima/AFP/Getty Images

Air France Flight 447’s crew reacted badly to an autopilot shutdown and misread instruments including a gauge indicating how fast the plane was losing height as it plunged into the Atlantic, killing 228 people, a report shows.

“I’ve lost VSI,” the junior co-pilot said of the Airbus’s vertical-speed indicator, according to a recording detailed in the report from court-appointed experts. In fact, the instrument was functioning normally, its analog needle immobilized at the lower limit because the plane was hurtling toward the ocean at 15,000 feet a minute, the document seen by Bloomberg News shows.

Flight 447 from Rio de Janeiro to Paris crashed on June 1, 2009, after ice-blocked speed sensors shut down the autopilot and the crew incorrectly reacted by pulling the jet into a steep climb until it slowed to an aerodynamic stall, France’s BEA accident investigation bureau said in May. The interim report from the criminal probe broadly endorses those findings.

“The aircraft’s stall went completely unnoticed by the crew, who made no reference to it,” according to the report, which was presented to victims’ families yesterday. Faced with unusual readings, the two co-pilots, alone at the controls while the captain was on a rest break, “rejected them en masse.”

Interface Issue

The document identifies no fault with the Airbus SAS A330, beyond the failure of Thales SA (HO) airspeed sensors that caused the autopilot shutdown. Manslaughter charges have been filed against Paris-based Air France and Toulouse, France-based Airbus as part of the criminal investigation, which could increase damages payouts if any criminal liability is established.

“This is an interim report and it’s impossible to draw any conclusions at this stage,” Air France lawyer Fernand Garnault said by telephone yesterday. “The real focus of this investigation is the man-machine interface, and why the pilots didn’t have everything they needed to understand what was happening.”

Air France had earlier suggested the stall alarm confused the A330’s pilots by shutting down when the jet slowed to a point where its computer was receiving no useful information, before sounding again when the speed picked up, misrepresenting what was actually a positive development. In reality, the junior copilot began pulling the nose up again before the alarm resumed, the criminal report suggests.

While referring to the aircraft’s artificial horizon as they struggled to keep its wings level, the co-pilots also disregarded indications from the same instrument that the plane was at a dangerous nose-up angle, the document says.

To contact the reporters on this story: Laurence Frost in Paris at lfrost4@bloomberg.net

To contact the editors responsible for this story: Chad Thomas at cthomas16@bloomberg.net; Benedikt Kammel at bkammel@bloomberg.net