Another report on the crash of Air France Flight 447 has leaked, this time indicating that it was malfunctioning air speed sensors, called pitot tubes, that caused the Airbus A330 to stall and then plummet into the Atlantic Ocean on June 1, 2009. The pitot probes drew attention less than a week after the crash and has been the most popular theory among aviation experts investigating the cause of the crash since. The theory was recently  described in a long New York Times Magazine article. Last week, though, an Airbus memo leaked suggesting crew error was to blame in the crash that killed all 228 passengers and crew.

Today's Bloomberg report, based on two unnamed sources within the investigation, comes days before France’s BEA air-accident investigation bureau is due to make a statement on the crash on May 27. The 'black box' flight data recorder and the voice recorder were both recovered at the beginning of May. It says the flight data recorder showed that the pitot tubes had malfunctioned and switched the plane to manual controls from autopilot as it flew through rough weather over the middle of the Atlantic. The co-pilots were at the controls and the plane's captain wasn't in the cockpit when the control switch happened, the report says. While shifting to manual controls shouldn't be a catastrophic event, it's possible that the pilots didn't notice the shift, and the plane lost too much speed and stalled.

The memo to Airbus customers earlier this month said they needed to make no updates to equipment. That may still be true, even if the pitot tubes are found to have been faulty on AFF 447. As the Times Magazine article points out, the company had slated all of its planes for new pitot tubes before the doomed flight ever took off, but they hadn't been replaced on that plane yet.