Germanwings co-pilot ‘intentionally’ crashed plane, black box indicates

The co-pilot of a Germanwings flight that slammed into an Alpine mountainside "intentionally" sent the plane into its doomed descent, a French prosecutor said Thursday.

Marseille prosecutor Brice Robin said the commander left the cockpit, presumably to go to the lavatory, and then was unable to regain access. In the meantime, he said, co-pilot Andreas Lubitz manually and "intentionally" set the plane on the descent that drove it into the mountainside in the southern French Alps.

It was the co-pilot's "intention to destroy this plane," Robin said. 

The information was pulled from the black box cockpit voice recorder, but Robin said the co-pilot did not say a word after the commanding pilot left the cockpit.

"It was absolute silence in the cockpit," he said.

The captain made several calls on the intercom system, but the co-pilot did not respond, and evidently de-activated the plane’s flight monitoring system.

During the final minutes of the flight's descent, pounding could be heard on the door as alarms sounded, he said.

The co-pilot did not respond to air traffic controllers and did not issue a distress signal, and prosecutors said they had not found any reason why. 

French, German and U.S. officials said there was no indication of terrorism. The prosecutor did not elaborate on why investigators do not suspect a political motive; instead they're focusing on the co-pilot's "personal, family and professional environment" to try to determine why he did it.

An analysis of transponder data by Flightradar24, a flight tracking service, showed that the autopilot was re-set to take the plane from 38,000 to 100 feet.

Robin avoided describing the crash as a suicide.

"Usually, when someone commits suicide, he is alone," he said. "When you are responsible for 150 people at the back, I don't necessarily call that a suicide."

In the German town of Montabaur, police searched the co-pilot's home in, leaving with large blue bags of evidence and a computer. A man was led out of the building, shielded by police holding up jackets.

Acquaintances in town said Lubitz was in his late 20s and showed no signs of depression when they saw him last fall as he renewed his glider pilot's license.

"He was happy he had the job with Germanwings and he was doing well," said a member of the glider club, Peter Ruecker, who watched him learn to fly. "He gave off a good feeling."

Lubitz had obtained his glider pilot's license as a teenager, and was accepted as a Lufthansa pilot trainee after finishing a tough German college preparatory school, Ruecker said. He described Lubitz as a "rather quiet" but friendly young man.

The Airbus A320, on a flight from Barcelona to Düsseldorf, began to descend from cruising altitude after losing radio contact with ground control and slammed into the remote mountain on Tuesday morning, killing all 150 people on board.

Lufthansa said the captain had more than 6,000 hours of flying time and been a Germanwings pilot since May 2014, having previously flown for Lufthansa and Condor, Lufthansa said.

Earlier on Thursday, an official with knowledge of the audio recordings said one of the pilots apparently was locked out of the cockpit when the plane went down.

The official, who was not authorized to speak publicly about the investigation, said that the details emerged from recordings recovered from the black box found on Wednesday among the debris of the aircraft.

The New York Times earlier quoted an unidentified investigator as saying someone could be heard knocking on the cockpit door.

One of the pilots is reportedly heard leaving the cockpit, then banging on the door with increasing urgency in an unsuccessful attempt to get back in.

"The guy outside is knocking lightly on the door and there is no answer," the paper quoted an unidentified investigator as saying. "And then he hits the door stronger and no answer. There is never an answer."

Eventually, the newspaper quotes the investigator as saying, "You can hear he is trying to smash the door down."

France's BEA air investigation bureau on Wednesday said the plane started descending a minute after reaching cruising height and lost altitude for over nine minutes. The pilot's last words to the ground confirmed the next navigational waypoint, ending with a call-sign and "thank you."

Pilots may temporarily leave the cockpit at certain times and in certain circumstances, such as while the aircraft is cruising, according to German aviation law. That's in contrast with U.S. Federal Aviation Administration rules that mandate "another qualified crew member" to come into the cockpit and lock the door if a pilot has to leave the cockpit for any reason, "until the pilot returns to his or her station.” 

Lufthansa said that its cockpit doors can be opened from the outside with a code, in line with regulations introduced after the Sept. 11 attacks. However, the code system can be blocked from inside the cockpit, according to an Airbus promotional video posted online and confirmed by the plane maker.

Al Jazeera and wire services