Germanwings co-pilot Andreas Lubitz rehearsed putting his aircraft into a controlled descent on the flight that preceded the crash of his jetliner into the French Alps on March 24, according to an interim report Wednesday by French air accident investigators.
The report by the French air accident investigation agency, the BEA, is based on analysis of the aircraft’s flight data recorders.
This indicates that on the flight out from Germany to Spain, “Several altitude selections towards 100 ft were recorded during descent on the flight that preceded the accident flight, while the co-pilot was alone in the cockpit.”
The data recorders indicate the captain had left Lubitz alone on the flight deck for less than five minutes.
On the return flight the same morning from Barcelona, Spain, to Dusseldorf, Germany, Lubitz is accused of purposely slamming Germanwings Flight 9525 into the French Alps, killing all 150 people on board, while the captain was locked out of the cockpit.
The co-pilot refused to let the captain re-enter and failed to respond to repeated contacts from air traffic controllers as the plane made its fatal descent.
Lubitz suffered from bouts of depression and the incident sparked a global debate over how to properly monitor the mental health of pilots.
The preliminary BEA report details what happened on board the Airbus A320 on both the outbound and return flights, which had the same crew of six.
While Lubitz was alone on the flight deck on the outbound flight, he was asked to bring the plane down to a lower altitude.
At one point, “the selected altitude decreased to 100 ft for three seconds and then increased to the maximum value of 49,000 ft and stabilized again at 35,000 ft,” the report said.
Less than two minutes later, “the selected altitude was 100 feet most of the time and changed several times until it stabilized at 25,000 ft.”
At this point the captain buzzed to re-enter the cockpit and the flight continued as planned to Barcelona.
Because he had already been asked to descend, Lubitz’s apparent rehearsal of different altitude settings would have gone unnoticed by air traffic controllers since he did not diverge from the flight plan.