The Germanwings co-pilot reportedly sped up as he flew the plane into the French alps

The second black box from the Germanwings flight 9525 crash has been recovered, and data extracted from it shows that the plane's co-pilot sped up as he flew the plane into the French alps last month.

French investigators said 27-year-old Andreas Lubitz "repeatedly accelerated the plane's descent" as it was going down, the BBC reports.

Investigators have said previously that Lubitz crashed the plane deliberately. The cockpit voice recorder revealed that he locked the plane's captain out of the cockpit and refused to open the door as the captain tried to break it down.

All 150 people on board the plane died in the crash.

Lubitz was reportedly suffering from depression and anxiety before the crash. He might have also developed a vision problem that could have threatened his career as a pilot.