The casing of a second black box has been found but not the box itself, French President Francois Hollande said as he came to the remote Alpine region with the leaders of Germany and Spain leaders to pay tribute to the 150 victims of Tuesday's (local time) crash.
"We just have been able to extract a useable audio data file," Remi Jouty, director of France's BEA air incident investigator told a news conference at its headquarters outside Paris.
But it was too early to draw any conclusions about the causes of the crash, he said.
"Detailed work will be carried on the file to interpret the voices and sounds that can be heard on the file," he said, adding that he expected to have more analysis of the voices in "a matter of days".
Jouty declined to give details of the recordings. While stressing it was too early to form a clear picture, he said the crash scenario did not appear to be linked to depressurisation and he ruled out a mid-air explosion having taken place.
Most of the victims are German or Spanish, including 16 German schoolchildren returning to Duesseldorf airport after a trip to the Barcelona region.
Hollande, Merkel and Rajoy thanked search teams and met residents in the village of Seyne-les-Alpes, where the salvaging operation has been set up.
"Dear Angela, dear Mariano, rest assured ... we will find out everything," a visibly moved Hollande told German Chancellor Angela Merkel and Spanish Prime Minister Mariano Rajoy, pledging to get to the bottom of what caused the crash. "France stands by you."
Merkel replied: "It feels good that in a difficult hour like this that we're standing so closely together in friendship. Dear Francois, I'd like to say to you a heartfelt 'thank you' in the name of millions of Germans who are deeply appreciative of this German-Franco friendship."
Hollande and Merkel had earlier flown over the nearby ravine where the Germanwings airliner came down.
Germanwings said 72 Germans were killed in Tuesday's crash, the first major air passenger disaster on French soil since the 2000 Concorde accident just outside Paris. Spanish officials said 51 Spaniards were among the victims.
"INEXPLICABLE"
A simple tribute ceremony took place on a site with a view in the distance of the mountain against which the Airbus crashed. French officials arranged it to give the families a mental image of the area in which their relatives died.
Earlier, Lufthansa said it could not explain why the Airbus run by its low-cost Germanwings unit crashed. Investigators said the remoteness of the crash site meant it could be days before a clear picture of the tragedy emerged.
However they said the fact that debris was restricted to a small area showed the A320 was not likely to have exploded in mid-air, suggesting a terrorist attack was not to blame.
"It is inexplicable this could happen to a plane free of technical problems and with an experienced, Lufthansa-trained pilot," Lufthansa chief executive Carsten Spohr told reporters in Frankfurt.
Lufthansa said the 24-year-old plane had on Monday had repairs to the hatch through which the nose wheel descends for landing. A spokeswoman said that was not a safety issue but that repairs had been done to reduce noise.
Police and forensic teams on foot and in helicopters investigated the site about 100 km (65 miles) north of Nice where the airliner came down en route to Duesseldorf from Barcelona.
"When we go to a crash site we expect to find part of the fuselage. But here we see nothing at all," said pilot Xavier Roy, coordinating air operations.
Roy said teams of investigators had been dropped by helicopter onto the site and were working roped together at altitudes of around 2,000 meters (6,000 feet).
It would take at least a week to recover all the remains of the victims, he said.
As well as Germans and Spaniards, victims included two Americans, a Moroccan and citizens of Britain, Argentina, Australia, Belgium, Colombia, Denmark, Israel, Japan, Mexico and the Netherlands, officials said. However DNA checks to identify them could take weeks, the French government said.
FLOWERS, CANDLES
Germanwings said it cancelled one flight on Wednesday and was using 11 planes from other carriers for about 40 flights after some of its crew members had refused to fly.
Employees laid candles and flowers by Germanwings headquarters at Cologne/Bonn airport, while Lufthansa and Germanwings staff worldwide held a moment of silence at 10:53 a.m. local (0953 GMT) - the moment the plane went missing.
Among the victims were 16 teenagers and two teachers from the Joseph-Koenig-Gymnasium high school in the town of Haltern am See in northwest Germany. They were on their way home after a Spanish exchange visit near Barcelona.
"On Tuesday last week we sent off 16 happy young people, with two happy young colleagues, on a journey and what was meant to be a happy trip ... has ended in tragedy," headmaster Ulrich Wessel told reporters.
Barcelona's Liceu opera house said two singers, Kazakhstan-born Oleg Bryjak and German Maria Radner, died while returning to Duesseldorf after performing in Wagner's "Siegfried".
Germanwings said on Tuesday the plane started descending a minute after reaching cruising height and lost altitude for eight minutes. Experts said that while the Airbus had descended rapidly, it did not seem to have simply fallen out of the sky.
The A320 is one of the world's most used passenger jets and has a good safety record.
At 24-years-old, the plane was older than many others at Lufthansa, where the average for its fleet is 11-and-a-half years. It was delivered to Lufthansa in 1991 and had clocked up around 58,000 flight hours over 46,000 flights, Airbus said.
