US safety regulators have cleared Boeing’s 737 Max plane to fly again, lifting grounding orders put in place in March 2019 after two deadly crashes. The move marks a key milestone for the firm, which was thrust into crisis by the tragedies and investigations that blamed it for the accidents.

Its financial woes deepened this year as air travel slowed due to the virus. Existing aircraft will need to be modified before going back into service, with changes to their design.

Safety regulator, the US Federal Aviation Administration (FAA), said the clearance would not allow the plane to “return immediately” to the skies. Alongside the software and wiring changes, pilots will also need training.

The approval comes roughly a year after Boeing had first hoped but too soon for many of the victims’ families.

Boeing and the FAA insist it will be – and certainly the direct cause of the accidents has now been fixed. Pilots and safety experts seem confident that the changes made to the plane will be effective.

But both Boeing and the regulator still have much to prove. For Boeing, the scathing criticisms of its corporate culture have been addressed, and that safety really is, as it often claims, its number one priority.

For the FAA, that it can stand up to the aerospace giant and recover from the failures that allowed a deeply flawed plane into service, resulting in tragedy.

The aircraft is coming back, but the world has changed. It was designed for a booming market, in which airlines desperately needed new planes and in which high fuel prices put a premium on efficiency.