BERLIN (AFP) - The co-pilot suspected of deliberately crashing an airliner in the French Alps searched online for information about suicide and cockpit doors, prosecutors said Thursday as it emerged the second black box had been found.

Authorities are hoping to unearth more clues about the disaster from the black box, which French prosecutors said was found after a nine-day search of the wreckage of the Germanwings plane.

The first voice recorder suggested that co-pilot Andreas Lubitz, 27, locked the pilot out of the cabin and sent the plane into a steep descent into the mountains.

The discovery came as German prosecutors revealed details of the browser history of a tablet computer found in his Duesseldorf flat.

It indicated the user had been researching "medical methods of treatment", "ways to commit suicide" as well as "cockpit doors and their security provisions", the prosecutor's office in the western city said.

German prosecutors have said Lubitz was diagnosed as suicidal "several years ago", before he became a pilot.

The second black box records technical flight data that could provide vital insights into the final moments of Flight 4U9525 before it crashed on Tuesday of last week, killing all 150 people on board.

The first black box, found the same day as the crash, recorded conversations between Lubitz and the pilot and showed that the German co-pilot was alone at the time of the crash.

Lubitz apparently took advantage of the captain's brief absence to lock him out and send the plane on its deadly descent.

The plane smashed into the mountains at a speed of 700kmh, instantly killing everyone on board - half of them German and more than 50 from Spain.

According to prosecutors, the voice recorder suggested that the passengers were unaware of what was going to happen to them until the very last seconds, when screams were heard.

Rescue workers have since been sifting through the wreckage for days trying to identify body parts and victims via their DNA.

The search for evidence has been hampered by the extremely difficult mountain terrain as well as the force of the crash.

'MY GOD'

The parent company of Germanwings, German flag carrier Lufthansa, has come under huge pressure after it emerged that Lubitz had informed his bosses that he had suffered from severe depression.

Lufthansa said the co-pilot had told the airline in 2009 about his illness after interrupting his flight training.

Doctors had recently found no sign that he intended to hurt himself or others, but he was receiving treatment from neurologists and psychiatrists who had signed him off sick from work a number of times, including on the day of the crash.

Police found torn-up sick notes during a search of his apartment after the crash.

French and German media claim to have seen a video purportedly showing the final seconds aboard the doomed airliner, which they said was shot on a mobile phone that somehow survived the crash.

"The scene was so chaotic that it was hard to identify people, but the sounds of the screaming passengers made it perfectly clear that they were aware of what was about to happen to them," said French weekly Paris Match.

People were heard crying "My God" in several languages, the magazine said.

Lufthansa said US$300 million (S$400 million) had been earmarked to cover the damages, while Germanwings will immediately compensate each family with 50,000 euros (S$70,000) - a sum that will not be deducted from any final compensation deal.

The catastrophe has dealt a heavy blow to the image of the German airline, which announced Tuesday it would cancel celebrations next month to mark its 60th anniversary.

Several airlines and countries around the world have since ruled that two authorised crew members must be present in the cockpit at all times.

Air France said that they have had two people in the cockpit since Wednesday as a "temporary" measure after the European aviation safety agency issued recommendations.