SISTERON, France — The father of one of the victims of this week's plane crash in the French Alps called Saturday for airlines to take greater care over pilots' welfare.
Prosecutors say they believe German co-pilot Andreas Lubitz deliberately slammed the Germanwings aircraft into a mountain, and that he hid an illness from his employers — including a sick note for the day of the crash.
"I believe the airlines should be more transparent and our finest pilots looked after properly," said Philip Bramley, from Hull in northern England. "We put our lives and our children's lives in their hands."
His 28-year-old son, Paul Bramley, was one of 150 people killed in Tuesday's disaster.
Speaking near the site of the crash, Philip Bramley said Lubitz's motive was irrelevant. "What is relevant, is that it should never happen again; my son and everyone on that plane should not be forgotten, ever," he said.
Germanwings, the Lufthansa subsidiary that Lubitz joined in 2013, declined Saturday to comment when asked whether the company was aware of any health problems he might have had. But it said he had passed all required medical check-ups.
Aviation experts say those checks are stringent, but focus mainly on physical health. A pilot's mental state is usually only assessed once, before companies decide whether to admit them to a training program — and even then a determined person could hide a latent problem.
"The test that will get you into a Lufthansa flight training program is a very hard test and this is why most people who get into those pilot classes will train for those tests," said David Hasse, the editor-in-chief of German aviation website airliners.de.
"There are coaching facilities, companies that are specialized in training people on how to pass those tests, and they will also advise you on how to behave in the psychological tests."
Lufthansa said pilots are required to pass an annual medical test overseen by the German Federal Aviation Office, but the company itself doesn't perform checks on its staff and relies on them to report any problems.
German prosecutors, who have been trying to determine what caused Lubitz to take such a devastating decision, met with their French counterparts Saturday to discuss the preliminary findings of their investigation.
Duesseldorf prosecutors say Lubitz hid evidence of an illness from his employers — including a torn-up doctor's note that would have kept him off work the day authorities say he crashed Flight 9525.
Searches conducted at Lubitz's homes in Duesseldorf and in the town of Montabaur turned up documents pointing to "an existing illness and appropriate medical treatment," but no suicide note was found, said Ralf Herrenbrueck, of the Duesseldorf prosecutors' office.
Prosecutors didn't specify what illness Lubitz may have been suffering from, or say whether it was mental or physical. German media have reported that the 27-year-old suffered from depression.
Duesseldorf University Hospital said Friday that Lubitz had been a patient there over the past two months and last went in for a "diagnostic evaluation" on March 10. It declined to provide details, but denied reports it had treated Lubitz for depression.
Colleagues and acquaintances described Lubitz as an affable man in good physical health who was focused on a career as a pilot.
Detlef Adolf, the manager of a local Burger King near Montabaur, said Lubitz worked their temporarily as a teenager and was "reliable and punctual."
Frank Woiton, another Germanwings pilot, said Lubitz told him he wanted to become a long-distance pilot and fly Airbus A380 or Boeing 747 planes. Woiton, who like Lubitz comes from Montabaur, said he met Lubitz for the first time three weeks ago when they flew Duesseldorf to Vienna and back together.
Woiton told German public broadcaster WDR on Friday that Lubitz didn't stand out and appeared like any other colleague. Lubitz "flew well and knew how to handle the plane," he said.
Lubitz also frequented a gliding club near the crash site as a child with his parents, according to Francis Kefer, a member of the club in the town of Sisteron.
Kefer told i-Tele television that Lubitz's family and other members of the gliding club in his hometown of Montabaur came to the region regularly between 1996 and 2003.
The crash site is about 50 kilometers (30 miles) away from the Aero-club de Sisteron glider airfield.
Jean Pierre Revolat, the club's vice-president, said he didn't recall Andreas Lubitz, but said the pilot's family had been friends with a former president of the club.
"As such they were coming here often to fly until the year 2000, 2003. As far as I know, since then we haven't seen that family," he said.
The area, with its numerous peaks and valleys and stunning panoramas, is popular with glider pilots. In the final moments of the Germanwings flight, Lubitz overflew the major turning points for gliders in the region, flying from one peak to another, according to local glider pilots.
The plane shattered into thousands of pieces, and police are toiling to retrieve the remains of the victims and the aircraft from a hard-to-reach Alpine valley near the village of Le Vernet.
A special Mass was held Saturday in the nearby town of Digne-les-Bains to honor the victims and support their families.
Frank Jordans reported from Berlin. Jill Lawless in London, David McHugh in Montabaur, Germany, Nicolas Garriga in Digne-les-Bains, France, and Elaine Ganley in Paris, contributed to this report.