France has opened a formal criminal investigation into the crash of an AirAsia plane in the Java Sea last month while a French co-pilot was at the controls, a judicial source said today.

A judge will investigate possible “manslaughter” in connection with the crash that killed all 162 people on board.

Flight QZ8501 went down in stormy weather on December 28 in the Java Sea during what was supposed to be a short trip from the Indonesian city of Surabaya to Singapore. Only 72 bodies have so far been recovered.

Yesterday, Indonesia’s National Transportation Safety Committee, which has been analysing the plane’s black boxes, said prior to the crash, the aircraft had climbed fast in an area packed with huge storm clouds, and the stall alarms started going off.

They also revealed that the Airbus A320-200’s less experienced French co-pilot, Remi Plesel, was flying the plane before it went down, rather than Captain Iriyanto, a former fighter pilot who had around 20,000 hours of flying time.

Plesel’s family in France separately filed charges against AirAsia Indonesia for “endangering the life of others” as the airline did not have permission to carry out the flight between Surabaya and Singapore on the day of the crash.

“Remi Plesel’s family are delighted at this criminal investigation which, we hope, will reveal the truth,” said their lawyer Eddy Arneton.

“It will allow us to finally ask the right questions.”