Two days on, investigators are finding it difficult to explain what caused the Germanwings aircraft with 150 aboard to crash. Evidence from a cockpit voice recorder, retrieved from the crash site in the French Alps, indicated that one pilot left the cockpit before the plane's descent and was unable to get back inside, The New York Times reports.
“The guy outside is knocking lightly on the door and there is no answer," The New York Times quoted an unidentified investigator. "And then he hits the door stronger and no answer. There is never an answer."
"You can hear he is trying to smash the door down," the investigator added.
However, the investigator said that they were unaware why the pilot left the cockpit. "But what is sure is that at the very end of the flight, the other pilot is alone and does not open the door," he told NYT.
Lufthansa, the parent company of Germanwings, does not have any information about the report, but is looking into it, company spokesman Klaus Gorny told CNN on Thursday.
The cockpit voice recorder also indicated that the plane hit the ground in the French Alps at great velocity, suggesting no explosion in flight.
Flight 4U 9525 from Barcelona to Duesseldorf crashed after an eight-minute rapid descent on Tuesday. Terrorism has been ruled out too and there was no evidence of foul play.
French President Francois Hollande, German Chancellor Angela Merkel and Spanish Prime Minister Mariano Rajoy visited the crash site on Wednesday to pay their tributes to those onboard the flight, all presumed to be dead including 16 schoolchildren.
