"Andreas Lubitz, the suicidal pilot, should never have been allowed to enter" the training program at Airline Training Center Arizona, Inc. (ATCA), said Brian Alexander, an attorney who filed the suit in federal court in Phoenix, Arizona.
It was filed on behalf of 80 people whose relatives perished in the March 24th 2015 crash of a Germanwings' Flight A320. Alexander's firm, Kreindler and Kreindler, was joined in the suit by attorneys in Britain, Germany and the Netherlands.
The crash took 150 lives, including that of Lubitz, a troubled pilot who had struggled for years with mental health problems.
The 27-year-old locked the pilot out of the cockpit and while alone at the controls, steered the jetliner into the side of a mountain, killing all 144 passengers and six crew.
The pilot, Captain Patrick Sondenheimer, can be heard on the "black box" recording retrieved from the crash site, banging on the cockpit door in the minutes before the crash, pleading with his young co-pilot to open it up.
Lubitz had received pilot training at ATCA between November 2010 and March 2011. ATCA, like the budget air carrier Germanwings, is owned by the German airline Lufthansa.
A spokeswoman for Lufthansa said the suit had "no chance of success," but declined further comment.
History of depression
Alexander said ATCA was "not just negligent, but also careless, and even reckless, in failing to apply its own well-advertised 'stringent' standards to discover the history of Lubitz's severe mental illness that should have kept Lubitz from admission to ATCA's flight school."
Investigators determined after the crash that Lubitz, 27, had a history of depression and suicidal tendencies and the case has raised questions about medical checks faced by pilots as well as doctor-patient confidentiality.
But the plaintiffs' lawyers said numerous red flags should have made it clear that Lubitz - with a history of serious mental illness that included suicidal tendencies - was unfit to be a pilot.
His struggle with depression and other mental illnesses before entering ATCA's program was sufficiently serious to require that he break off his pilot's training for ten months and receive treatment in hospital, the lawyers said in their suit.
Lubitz had filed false documentation with the US Federal Aviation Administration, deliberately concealing "his true medical history, past medical diagnoses and lengthy treatment, including hospitalization, for multiple psychotic and mental disorders," the lawsuit said.
Still, the German medical certificate Lubitz presented to ATCA bore a notation that indicated the certificate would be invalidated if there were a relapse or recurrence of his depression, according to the lawsuit.
And while Lubitz's FAA medical certificate carried no notation, it was issued with a warning about his history of "reactive depression" that would bar him from flying if it recurred, the suit said.
If not for their negligence, officials at ATCA could have known, and should have been able to disclose to US aviation authorities, the disqualifying details of Lubitz's medical history, the suit maintains.
"ATCA failed to use reasonable care to determine whether Lubitz's medical history of a severe mental disorder, including suicidal ideation, indicated a continuing lack of mental fitness and presented a risk of a recurrence or relapse which made him unqualified to be a commercial airline pilot," the text of the lawsuit said.
The plaintiffs are not seeking a specific dollar amount, but are asking for "just, full and fair compensation" for the "pain, mental suffering, grief, sorrow, stress, shock they each sustained by reason of their loved one's murder," the text of the suit said.
New rules for pilots
Further fallout from the Germanwings tragedy came in the Bundestag (German parliament) on Thursday, as MPs agreed on a stricter drug and alcohol testing regime for pilots.
The new law will oblige airlines to test new hires for medications, alcohol, or other psychoactive substances if they suspect they might be using them.
It also provides for random checks of flight crew to catch users of such substances before they become a danger.
German Transport Minister Alexander Dobrindt said during the parliamentary debate that experts across the globe agreed such checks would improve air safety.
Note: This AFP article has been updated to correct the date of the crash.