BERLIN - The copilot of Germanwings Flight 9525 used the onboard autopilot to put the plane into a descent and repeatedly increase the speed of the Airbus A320 as it headed straight for a mountainside, according to an initial assessment of data recovered from the aircraft's second black box.

The readings, announced by French investigators on Friday, appeared to add to the growing body of evidence indicating that Andreas Lubitz, the 27-year old German who copiloted the plane, deliberately locked its more senior pilot out of the cockpit before crashing the jetliner with 149 other people on board.

On the first black box, the voice data recorder recovered last week, the pilot is heard desperately trying to reenter the cockpit after he had briefly left for what appeared to be a bathroom break.

There are also sounds, investigators say, of the pilot trying to break down the door while calling Lubitz's name.

But investigators have been waiting for further confirmation of the events on board that could only be provided by the second black box, the data recorder found on Thursday by a ravine and buried under debris.

A preliminary review, French investigators said, shows that from a cruising altitude of 38,000 feet, Lubitz appears to have adjusted the autopilot, putting the plane into a descent to 100 feet.

At various times, he accelerated the Airbus A320 using the plane's autopilot settings, building up speed as the craft approached a part of the French Alps where the copilot is known to have spent vacations.

The Germanwings jetliner would eventually crash just above 6,000 feet, and before it reached its new setting.

The information gleaned so far is still preliminary, and investigators are hoping a more detailed review will shed more light on the events that transpired in the cockpit. Data recorders capture a vast array of systems information, including more than 500 parameters on speed, altitude, and the pilots' actions at the controls.

Although the device found on Thursday was badly charred from fire, its condition, officials said, still offered reasonable hope for substantial data retrieval.

Yet even the initial information from the recorder seemed to confirm evidence that Lubitz actively endeavored to crash the plane, adding to a picture of a troubled man who may have committed premeditated mass murder on the March 24 flight from Barcelona to Dusseldorf.

The fact that Lubitz appeared to increase the plane's speed before the crash, experts say, may have suggested his mounting concern as the pilot sought to reenter the cockpit.

"From what I've seen today, my guess is that when he heard the second pilot was trying to get back into the cockpit, [Lubitz] became stressed and wanted to increase the speed and crash before the pilot might have been able to get through the door," said Mikael Robertsson, cofounder of the flight data tracking company Flightradar24.

The investigation now is basically working on two fronts - one in Germany, where authorities continue to canvas Lubitz's doctors, medical records, family and friends, and one in France, where investigators continue to comb through the crash site.