BERLIN — After acquiring a pilot's license, regular medical examinations and constant security checks are part of the job for Luftansa pilots, but psychological tests aren't repeated. Andreas Lubitz, the 27-year-old German co-pilot who authorities believe deliberately crashed the Germanwings Airbus A320 Tuesday in the French Alps, had been treated for a "major depressive episode" in 2009, the German daily Bild has reported.

Lufthansa, which owns Germanwings, gives aspiring pilots an aptitude test specifically designed in collaboration with the German National Center for Aeronautics and Space Research, company director Carsten Spohr says.

This aptitude test is "recognized globally." Conspicuous behavior that manifests itself later on, he says, can be observed and reported by colleagues. But it's very rare for the same crew to spend more than a few days in each other's company, and behavior that would raise flags would have to be extreme to be noticed immediately.

Quoting internal Lufthansa documents and sources, Bild reported that Lubitz underwent 18 months of psychiatric treatment and was forced to repeat his flying classes because of depression before finishing his training. It also reported that a Lufthansa flight school in Phoenix, Arizona, where Lubitz was trained, had designated him as "not suitable for flying" at the time.

Spohr, however, declines to comment about Lubitz's medical record, saying it's subject to doctor-patient confidentiality. But trainee pilots generally must pass all medical exams with flying colors before re-commencing their training. This was the case with Lubitz, Spohr confirms.

A photo taken from Andreas Lubitz" Facebook page.

In the case of psychological stress, pilots can turn towards specialists employed by Lufthansa who are at their service day and night. But many pilots believe themselves to have strong problem-solving abilities, seeing as they are forced to overcome constant training and dealing with technical difficulties on the job, and therefore don't seek help .

Before any direct contact with recruiters, potential pilots must fill out an extensive online questionnaire before even hoping to be taken on as a trainee at the flight school in Bremen. Afterwards they are invited to take part in a three-day marathon of technical and psychological tests before their suitability for the role is decided.

Before they begin their actual training, they are required to undergo a wide range of medical examinations and are also drug tested. But throughout their actual employment, drug abuse would only be flagged during annual medical check-ups.

Regular security checks

Before being admitted to flight school, each applicant undergoes security checks, as is the case with all airline employees. A factor in these investigations is, among other things, the police clearance certificate. Authorities request this information from police and internal security agencies and forward that information to airports and airlines.

This particular security check has to be repeated after five years. If any misconduct has been recorded by the police, it is immediately forwarded to the employer, and pilots may be suspended until the matter has been fully investigated.

At Lufthansa, specific emphasis is placed upon the development of pilot flying abilities. Therefore, all pilots begin and develop their skills in small aircrafts at the Lufthansa training center in Phoenix, Arizona. There, upon the walls of the training center, all previous years' photos are displayed to convey the sense that all pilots are part of that small but distinguished elite.

Normally, all trainee pilots fly small aircraft while accompanied by their flying instructor. The hot air can result in strong turbulence, which can cause the trainees to feel ill. Nonetheless, trainee pilots are never allowed to lose control of the aircraft.

The bond between budding pilots is strengthened by having mastered the physical and psychological difficulties together. During their employment, commissioned pilots are medically examined annually to determine their airworthiness. But their psychological condition is neither examined nor monitored.