— The co-pilot 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 Friday, appeared to add to the growing body of evidence indicating that Andreas Lubitz, the 27-year old German who co-piloted 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 events onboard that could be provided only by the second black box, a data recorder found Thursday near 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 plane using its autopilot settings, building up speed as the craft approached a part of the French Alps where the co-pilot is known to have spent past vacations. The plane would eventually crash just above 6,000 feet, and before it reached its new setting.

The information gleaned so far is preliminary, and investigators are hoping a more detailed review will shed greater light on what 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 Thursday was badly charred, it still offered reasonable hope for substantial data retrieval, officials said.

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 might have committed premeditated mass murder on the March 24 flight from Barcelona to Düsseldorf.

On Thursday, German investigators said they found evidence that Lubitz had been trawling the Internet for ways to commit suicide and information about the safety mechanisms on cockpit doors.

German officials said Lubitz had used a tablet computer between March 16 and 23 to search for information on “ways and implementation possibilities of killing himself,” as well as other unspecified “medical treatment methods.” On at least one day, investigators said, his browsing history showed that he had spent “several minutes” on a site that explained the workings of cockpit locks and security systems.

German authorities did not provide details about which Web sites Lubitz had visited or what search terms he had used. Investigators were still combing through items seized from Lubitz’s two German homes, in Montabaur and Düsseldorf, including an iPad and a laptop computer.

The investigation is working on two fronts — one in Germany, where authorities continue to survey Lubitz’s doctors, medical records, family and friends, and one in France, where investigators are combing through the crash site.

According to the German outlet Spiegel Online, prosecutors in Düsseldorf searched at least five doctor’s offices and secured Lubitz’s medical files. Several doctors contacted authorities after his name became known, claiming Lubitz had consulted them. Among them were experts in neurology and psychiatry.

Officials have sealed at least 470 personal effects found at the site, including 40 cellphones, according to the French Interior Ministry.

Normally, experts say, it takes almost a month to provide a comprehensive analysis of a flight data record. But French authorities in this case appear to be seeking an accelerated process.

“The more we know about the medical history and iPad researches of the co-pilot,” the less likely it is that the crash was anything but intentional, said Xavier Tytelman, a French aviation safety specialist.

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, co-founder of the flight data tracking company Flightradar24.

Stephanie Kirchner in Berlin and Cléophée Demoustier in Paris contributed to this report.

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