The families of the victims on the Germanwings plane, which was deliberately crashed into the French Alps by co-pilot Andreas Lubitz, are suing the flight school in the US where he underwent training.
The suit claims that the school failed to properly screen his medical background.
The case was filed in the US District Court in Phoenix against the Airline Training Centre of Arizona (ATCA) which is owned by Lufthansa, the parent company of Germanwings.
While training in Europe with Lufthansa, Lubitz had been suspended from his academic course work for nearly 10 months while he sought treatment for depression.
In 2010, after returning to Lufthansa, he was sent to Arizona for flight training.
The wrongful death suit, on behalf of 80 families, alleges that if the school screened Lubitz before offering him training, it would have discovered that he'd been previously been in hospital for severe depression and treated with medications that would have prohibited him from flying.
In March last year, Lubitz deliberately steered the Germanwings flight into the mountains after locking the pilot out of the cockpit.
All 150 people aboard, including Lubitz, were killed.
In a press release accompanying the suit, attorney Marc S. Moller said: "Lubitz’s particular history of depression and mental instability made him a suicide time bomb, triggered to go off under the ordinary stresses of life, particularly the kind of stresses a commercial pilot routinely faces.
"The fuse which culminated in Lubitz’s suicide on March 24, 2015, that took the lives of 149 passengers and his fellow crew-mates, was lit when ATCA negligently allowed him to begin commercial pilot training."