Pilot of Germanwings flight may have left cockpit before crash.

Airline officials have admitted they don't have the 'slightest explanation' for Tuesday's plane crash in France – which left 150 people dead.

It's claimed one of the pilots left the cockpit before it went down and was unable to get back in. 

The New York Times cites a senior investigator with access to information from the recovered black box voice recorder.

There's been no official confirmation.