The Boeing 737 Max has been cleared by the the European Union Aviation Safety Agency (EASA) and the UK's Civil Aviation Authority (CAA) to return to the skies, two years since the fleet was grounded globally following two fatal crashes.
The clearance follows that of the US Federal Aviation Administration (FAA), which certified the plane to fly late in 2020.
Its comes after a US congressional report into the crashes said that Boeing's decision to ignore warnings over internal safety concerns, and a lack of guidance over required pilot training, contributed to the crash. It also criticised the lack of oversight from the FAA itself.
The FAA has committed Boeing to making design changes to wiring and software, and mandating further pilot training. It will be the FAA, rather than Boeing that will issue the airworthiness certificate for each plane in future.
The European Union Aviation Safety Agency had been working alongside the FAA in conducting tests on the modified plane. It has also conducted its own independent tests.
A spokesperson said: 'We have every confidence that the aircraft is safe, which is the precondition for giving our approval. But we will continue to monitor 737 MAX operations closely as the aircraft resumes service.'
It's not yet clear when airlines in Europe may return the Boring 737 Max to service.
The Boeing 737 Max has also been certified for flights in the UK. Since the end of the Brexit transition period it is the UK's Civil Aviation Authority that issues airworthiness certificates.
It said that EASA work formed the basis for the UK decision. A spokesperson said: 'u201cThis is not a decision we have taken lightly and we would not have allowed a return to service for UK operators, or lifted the ban on the aircraft operating in UK airspace, unless we were satisfied that the aircraft type is airworthy and can be operated safely,u201d
Relatively few airlines operating from the UK have ordered the 737 Max. The biggest that has is Ryanair, followed by Tui.
We asked both airlines what passengers can do if the plane does enter service and they don't want to travel on it.
It told Which?: 'If Ryanair does start flying the Boeing 737 MAX in 2021, it will do so following the most extensive certification process ever conducted by the FAA, EASA and other international regulators.'
Which? asked Ryanair whether it would allow customers to amend fee-free to an alternate flight or route to avoid the aircraft, in the instance of the customer having already booked tickets on a route where the Boeing 737 Max is subsequently introduced. It said it wouldn't. Nor would it alert customers making future bookings with Ryanair if the flight might be operated by a 737 Max.
It said: 'It will be impossible for Ryanair to make clear to customers (who book on average 10 weeks in advance of travel) which flights any individual aircraft will operate given that - like all airlines - aircraft allocation decisions are only made the day before a flight departure.'
Tui also said it will only fly the 737 Max after EASA has approved it and when it 'believes it is safe to do so'. It said that this wouldn't happen this winter season.
It was positive about helping passengers avoid the 737 Max who are worried about flying on it. It told Which? that if a customer is due to fly on a 737 and would like to change 'they will be allowed to move without an amendment fee'.
It said it was also taking steps to indicate to customers making future bookings if the flight may be operated by the 737 Max, saying: 'Before we reintroduce the 737 MAX into our fleet we will be looking at the best way to inform customers and is our intention to do so.'
One of the main benefits of the 737 Max is that it has a lower carbon footprint than most rival aircraft, significantly so in some cases.