Pilots aboard an Air France plane whose plunge into the Atlantic killed 228 people were confused by a series of flight control alarms and possibly reacted in error before the crash, according to The Wall Street Journal.

It said sources familiar with the preliminary findings of the investigation found the pilots failed to follow standard procedures as they wrestled to figure out what was happening.

The Airbus A330 en route from Rio de Janeiro to Paris on June 1, 2009 ran into heavy turbulence and icing that could have generated erroneous airspeed data and warnings, distracting the three pilots as the aircraft lost engine thrust.

The crew struggled to make sense of the different warning messages and chimes while also monitoring key indicators of the plane’s trajectory and engine power, the Journal said.

Two flight recorders were recovered from the wreckage early this month using a robot submarine.

The report said the investigation will likely show that the autopilot of the aircraft, travelling at 10,700 metres, cut out as it ran into turbulence and then decelerated to a dangerously slow speed.

The pilots then faced a series of automation failures or disconnects linked to troubles with the aircraft’s airspeed sensors, according to the Journal.

It also said they had never been trained to deal with such an emergency situation.

Speculation centres on the theory that the plane’s pitot tubes or speed probes iced up, resulting in faulty information on the aircraft’s airspeed.

The Journal said Airbus had registered 32 instances of the same problem on similar aircraft between 2003 and 2009.

Investigators are expected to reveal their findings from the black boxes on Friday.