Authorities are hoping to unearth more clues about the disaster from the black box after the first voice recorder suggested that co-pilot Andreas Lubitz deliberately locked the plane on a collision course with the mountains.

The second black box gathers information about the speed, altitude and direction of the plane.

Investigators have already solved a great deal of the mystery of Flight 4U9525 thanks to the first black box, which contained audio recordings from inside the cockpit, and which revealed that the 27-year-old co-pilot was alone at the time of the crash.

He apparently took advantage of the captain's brief absence to lock him out and set the plane on a deadly descent into the Alps.

The plane smashed into the mountains at a speed of 700 kilometres an hour, instantly killing all 150 people on board — half of them German and more than 50 from Spain.

According to prosecutors, the voice recorder suggested that the passengers were unaware of what was going to happen to them until the very last seconds, when screams were heard.

Rescue workers have since been sifting through the wreckage for days trying to identify body parts and victims via their DNA.

The search for evidence has been hampered by the extremely difficult mountain terrain as well as the force of the crash.