A Germanwings pilot was locked out of the cockpit before the deadly crash in the French Alps, an investigator said audio from a cockpit voice recorder revealed.
Speaking to the New York Times, an unidentified senior military official investigating the crash said one of the pilots exited the cockpit and was unable to re-enter.
“The guy outside is knocking lightly on the door and there is no answer,” the official said. “And then he hits the door stronger and no answer. There is never an answer.”
[sharequote align="right"]"But what is sure is that ... the other pilot is alone and does not open the door."[/sharequote]
"You can hear he is trying to smash the door down," the investigator added.
The official told the Times that "the reason why one of the guys went out" was not yet clear to officials.
"But what is sure is that at the very end of the flight, the other pilot is alone and does not open the door," the official said.
The Germanwings plane fell approximately 38,000 feet from the sky in about 10 minutes, crashing in the French Alps Tuesday and killing all 150 people aboard.
The audio taken from the plane has offered clues as to what happened, but has also left investigators with many questions. Air traffic controllers received no emergency communication from the aircraft before it crashed.
Rescue workers work on debris at the plane crash site near Seyne-les-Alpes, France, Wednesday, March 25, 2015, after a Germanwings jetliner crashed Tuesday in the French Alps. (AP Photo/Laurent Cipriani)
With no distress call or other indication of anything out of the ordinary, French investigators struggled Wednesday to solve the mystery. While alarming, the descent was still gradual enough to suggest the plane was under the control of its navigators.
"The descent is compatible with a plane controlled by pilots," said Remi Jouty, the head of the accident investigation bureau, or BEA. "It is also compatible with a plane controlled by automatic pilot."
"At this point, there is no explanation," he added. "One doesn't imagine that the pilot consciously sends his plane into a mountain."
Martine del Bono, a spokeswoman for France's Bureau of Investigations and Analysis, declined to comment to the Times on the new evidence.
"Our teams continue to work on analyzing the CVR,” she said. "As soon as we have accurate information we intend to hold a press conference.”
Lufthansa CEO Carsten Spohr, himself a pilot, said he found the crash of a plane flown by two experienced captains while at cruising altitude "inexplicable." Cruise is considered the safest part of a flight, with only about 10 percent of crashes occurring at that altitude.
"We still cannot understand what happened there yesterday," he said. "Lufthansa has never in its history lost an aircraft in cruise flight and we cannot understand how an airplane that was in perfect technical condition, with two experienced and trained Lufthansa pilots, was involved in such a terrible accident."
The four possible causes of any crash are human error, mechanical problems, weather, criminal activity or any combination of these. Investigators use the cockpit voice and flight data recorders to focus their work, said Alan E. Diehl, a former air safety investigator with the National Transportation Safety Board.
The Associated Press contributed to this report.
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