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The US flight school where the co-pilot who crashed a Germanwings aircraft into the French Alps was trained is being sued by families of those killed.

The lawsuit alleges the Airline Training Center of Arizona failed to properly screen Andreas Lubitz, the BBC reported.

Lubitz locked the aircraft’s captain out of the cockpit before flying it into the Alps in March last year. All 150 people on board were killed.

He had struggled for many years with mental health problems.

Investigators found that weeks before the crash a doctor had urged him to attend a psychiatric hospital but his employer was never alerted.

Lubitz received training at the ATCA, owned by Germanwings’ parent company Lufthansa, from 2010-2011.

The lawsuit, filed in Phoenix, Arizona, alleges the school was negligent in admitting him by failing to discover his medical history.

Families of 80 of the victims are involved in the legal action, which also involves lawyers in the UK, Germany and the Netherlands.

A spokeswoman for Lufthansa said the action had “no chance of success”. The school is yet to comment.