Investigators will conduct a flight with an Airbus A320 to validate sounds picked up by the cockpit voice recorder of the Germanwings aircraft that crashed in the French Alps on 24 March.
German transport ministry Alexander Dobrindt had said the flight would be operated in May "along the same line [path]" but France's BEA – which is leading the investigation – tells Flightglobal the test flight will not, in fact, follow the Germanwings A320's flight trajectory.
The authority declined to specify what aircraft or route would be used. But it says the test aircraft will not take off from Barcelona, the city from where the Germanwings flight had departed.
The aim is not to simulate events on board that aircraft before it crashed, says BEA. Instead, the investigators want to ensure that the sounds of selector knobs and switches being used – as recorded by the CVR on the Germanwings flight – can be precisely attributed to specific controls in the cockpit.
This will require flying the aircraft at altitudes and speeds similar to those of the Germanwings A320 to create a representative audio atmosphere.
The CVR picked up sounds of switches and knobs being operated during the aircraft's descent from cruising altitude. Some of these sounds can be correlated to flight-parameter changes on the flight data recorder (FDR), but it is not possible to be definitive for all of them, the authority indicates.
During the validation, BEA says, investigators will exclusively focus on sounds associated with cockpit switches and knobs. They will not direct attention to other audio such as that related to cockpit chairs' movement or the door to the flightdeck.
Dobrindt says the co-pilot's capacity to act throughout the descent has been "fully proven". FDR data shows that the first officer not only changed the altimeter and speed settings several times but also "actively used the control organ [sidestick]" during this period, he says.
"These three elements are verifiable on the FDR and thus [make] conclusively clear that the co-pilot intervened several times consciously to bring that aircraft to a crash," he says.
Dobrindt made the comments after updating the German parliament's transport committee on the accident investigation, together with Lufthansa Group chief executive Carsten Spohr.
A preliminary report is to be published within weeks, says Dobrindt.
All 150 passengers and crew were killed when apparent deliberate action by the first officer caused the aircraft to crash during a flight from Barcelona to Dusseldorf.