SEYNE-LES-ALPES/PARIS - Investigators have retrieved cockpit voice recordings from one of the "black boxes" of the German jet that crashed in the Alps, killing everyone onboard, and the New York Times said the audio showed one of the pilots left the cockpit and could not get back in before the plane went down.
"The guy outside is knocking lightly on the door and there is no answer," an unnamed investigator told the Times, citing the recordings. "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.
The retrieval of the recordings came as French President Francois Hollande, Germany's Angela Merkel and Spain's Mariano Rajoy travelled to the crash site in a remote French Alpine region to pay tribute to the 150 victims, mostly Germany and Spanish.
However, while Hollande promised that authorities would not rest until the causes of the crash were known, France's BEA air incident investigation bureau said it was still far too early to draw meaningful conclusions on why the plane, operated by the Germanwings budget arm of Lufthansa, went down.
"We have just been able to extract a useable audio data file," BEA director Remi Jouty told a news conference at the agency's headquarters outside Paris.
"We have not yet been able to study and to establish an exact timing for all the sounds and words heard on this file."
Jouty expected the first basic analysis in "a matter of days" but warned this read-out could be subject to errors and that more work would be needed for a full interpretation.
Although he said "words" had been heard on the tape, Jouty would not confirm whether that meant the Airbus A320's pilots were conscious and he gave no details of the recordings.
The New York Times quoted a senior military official involved in the investigation as saying the cockpit audio showed "very smooth, very cool" conversation between the pilots in the early part of the flight. The audio then indicated one of the pilots left the cockpit.
"We don't know yet the reason why one of the guys went out," the official added. "But what is sure is that at the very end of the flight, the other pilot is alone and does not open the door."
A Lufthansa spokesman said the carrier was aware of the Times story, adding: "We have no information from the authorities that confirms this report and we are seeking more information. We will not take part in speculation on the causes of the crash. "
He said that since the Sept. 11, 2001, hijacked plane attacks on the United States, cockpit doors cannot be opened from the outside, in line with regulations.
Interior Minister Bernard Cazeneuve earlier said a terror attack was not the main hypothesis. Jouty said, however, that no theory could be excluded yet.
While stressing it was too early to form a clear picture, he ruled out a mid-air explosion and said the crash scenario did not appear to be linked to depressurization.