Marseille prosecutor Brice Robin named the crashed Germanwings co-pilot as Andreas Lubitz. In the German town of Montabaur, acquaintances said Lubitz (28) showed no signs of distress when they saw him last autumn.
"He was happy he had the job with Germanwings and he was doing well," said a member of a glider club, Peter Ruecker, who watched him learn to fly. "He gave off a good feeling."
Lubitz had obtained his glider pilot's license as a teenager and was accepted as a Lufthansa pilot trainee after finishing a tough German college preparatory school, Mr Ruecker said. He described Lubitz as a "rather quiet" but friendly young man.
The Airbus A320, on a flight from Barcelona to Duesseldorf, began to descend from cruising altitude after losing radio contact with ground control and slammed into the remote mountain on Tuesday morning, killing all 150 people on board.
Lufthansa has not identified the pilots but said the co-pilot joined Germanwings in September 2013, directly after training, and had flown 630 hours.
The captain had more than 6,000 hours of flying time and had been a Germanwings pilot since May 2014, having previously flown for Lufthansa and Condor, Lufthansa said.
Investigators will now delve in to the personal life of Mr Lubitz to uncover any clues about his mental state after the revelation that the co-pilot deliberately crashed his own plane killing 150 people, an aviation psychologist said. Professor Robert Bor, a specialist aviation psychologist in London, said Mr Lubitz could have been attempting to destroy all evidence of his suicide bid by flying in to a mountain.
He said pilots are subject to “enormous scrutiny” and it would be rare for airlines not to identify a pilot suffering mental health problems. “The very first thing the aviation authorities and investigators will do is go through his personal background and look at his professional life, in terms of his relationships, finances, flying record and medical record,” he said. “They will also be interviewing pilots he has flown with over the last few weeks to see if there is anything about his behaviour, attitude or professional conduct that could be potentially relevant here.
“It’s an extremely rare thing for a pilot to crash his own plane.
“Taking an aircraft full of passengers with you and flying in to a mountain suggests you are trying to destroy all the evidence of your suicide attempt.
“But as we have the black box and the recording, he was not very successful in hiding it — if indeed that is what has happened.
“We need to look in to the mind of the person. Unfortunately he is no longer alive but we do leave so-called psychological footprints before we act in this kind of way.
“There is also the possibility that this was an impulsive act at the time, which he had not thought of previously. But it is much more likely to be an issue with the personal life of the pilot. Probably there will be answers to these questions quite soon.”
He added that pilots are a very “stable part of the population” who do not usually exhibit psychological problems and who are subject to “enormous scrutiny”. It includes two medical checks a year and regular contact with their airline, as well as being closely watched by their colleagues every time they fly. “Every time they arrive at an airport they have to check in and meet with other staff — to not spot a pilot with mental health problems would be quite rare.”