Germanwings plane crash: Black box data extracted

French investigators say usable data has been extracted from the cockpit voice recorder of Germanwings 4U 9525 but it has so far yielded no clues as to the cause of the plane's crash.

They said the plane hit the ground in the French Alps at great velocity, suggesting no explosion in flight.

Flight 4U 9525 from Barcelona to Duesseldorf crashed after an eight-minute rapid descent on Tuesday.

Richard Westcott reports.