Continued from page 1

Turbulence caused the pilots to make a slight change of course, but was not excessive as the plane tried to negotiate a normal path — passing through a heavy layer of clouds.

Four minutes later, the plane’s autopilot and auto-thrust shut off, the stall alarm sounded twice and the co-pilot at the controls, 32-year-old Pierre-Cedric Bonin, took over manual control. A second co-pilot, David Robert, 37, was also in the cockpit.

Pilots on long-haul flights often take turns resting to remain alert. Dubois returned to the cockpit about a minute and a half after the problems started but did not take back the controls.

Just over two minutes before the crash, Bonin is heard to say “I don’t have any more indications.” Robert says “We have no valid indications.”

The interim report by accident investigation agency BEA did not analyze the data or cockpit conversations or assign blame. A full report on the crash is not due until next year.

Air France said in a statement that, based on the report, it appears “the initial problem was the failure of the speed probes which led to the disconnection of the autopilot” and loss of pilot protection systems.

The airline defended the captain, saying he “quickly interrupted his rest period to regain the cockpit.”

Independent aviation analyst Chris Yates said the report appears “to raise more questions than it answers.”

“It would seem to me, reading between the lines, that the cockpit crew weren’t confident of the information that was being presented to them on the data displays. Maybe — and it’s only a maybe — they took some action that led to the stall warning, and the plane stalling and then being unable to correct it.”

The flight recorders were found along with bodies in early May in the latest in a series of meticulous searches using small submarines and robots to comb the ocean depths.