Europe’s aviation safety regulator has presented Boeing with a list of outstanding issues it wants the US aircraft maker to resolve before it will allow the 737 Max back into the skies.
The European Aviation Safety Agency set out a detailed list of topics in a letter addressed to senior management at Boeing as well as at its US counterpart, the Federal Aviation Administration, in the past few days, two people close to the situation confirmed.
EASA has been working with the FAA and other regulators in reviewing a number of changes Boeing has proposed to the flight control system of the 737 Max, which has been grounded since March after two deadly crashes that killed 346 people.
The crisis has battered Boeing’s reputation as well as that of the FAA, whose role in originally certifying the plane has come under scrutiny. The US company has been working on a software fix for the MCAS anti-stall system that has been implicated in both crashes, but additional issues have surfaced in recent weeks.
“These are things that need to be resolved before EASA lifts the ban on the Max. Some of them are being worked on but not yet all to its satisfaction,” said one person familiar with the situation.
The issues cited in the letter include resolving a new software flaw in the flight control system identified during simulator training by the FAA where an on-board computer appeared to become overloaded and it took the pilots too long to recover the plane from a stall.
The emergence of the new issue prompted Southwest Airlines, the largest 737 Max operator, to push back the reintroduction of the plane into its flight schedules until October 1, a month later than previously planned. Boeing has said it is working on the issue.
EASA also wants Boeing and the FAA to assess whether the average pilot has enough physical strength to turn the trim wheel in the cockpit, an emergency manual crank to help change the angle of the plane’s nose.
Other issues include reviewing how the autopilot engages and disengages when the plane approaches a stall as well as the crew procedures needed to deal with multiple emergency alerts. Another issue highlighted is the apparent failure of the angle of attack sensors in both planes that crashed; a faulty sensor is believed to have triggered the MCAS system.
“EASA is looking closely at better training needed [for pilots] as well as the prioritisation of the cockpit alerts,” said the person familiar with the situation, adding that the agency was working “in full co-ordination with the FAA”.
The crisis has prompted concerns of a splintering among regulators and whether the current system, whereby safety agencies accept each other’s certification as a matter of course, can survive.
The FAA was the last agency to ground the plane and EASA has made clear it is conducting its own independent review.
EASA declined to comment. Boeing declined to comment on the letter but said it continued to “engage with regulators and providing information as we work towards the safe return to service for the Max”.
The US regulator said on Friday: “The FAA continues to work closely with other validating civil aviation authorities on our review of Boeing’s certification documentation for the 737 Max. This process involves regular communications among all parties.”
A person close to the process added: “The questions EASA is asking are consistent with the FAA’s own questions.”
But even as the US agency battles to remain in control of the process, it remains without a permanent head — a problem that was exacerbated on Friday when a senior Democratic senator said she would vote against the man proposed by President Trump to take the position.
Maria Cantwell, the most senior Democrat on the Senate commerce committee, said she would vote against the appointment of Stephen Dickson, who has been accused of retaliating against a whistleblower while working for Delta Air Lines. The committee must approve his appointment before it goes ahead.
Karlene Pettit, a pilot at Delta, has brought a lawsuit against the airline, in which she says Mr Dickson ordered her to undergo a mental health examination after she warned of safety lapses at the company.
Delta denies that executives there retaliated against Ms Pettit. Mr Dickson could not be reached for comment, but his failure to mention the lawsuit has angered senators on both sides of the Senate commerce committee.
Mr Dickson has been explaining his position to members of the committee in recent weeks, but Ms Cantwell said she had not been persuaded by his explanations, and has now become the first member to say openly she will oppose his nomination.
She said in a statement: “Given the urgent need for stronger safety culture and transparency throughout the FAA, these incidents do not paint the picture of the type of leadership that we need. Mr Dickson’s oversight of these matters raises serious questions about his leadership, and therefore I will not support his nomination.”
Donald Trump however continues to stand by his pick, a spokesperson said on Friday.
If Republican senators support the president, they will be able to outvote Ms Cantwell and any other Democrat who joins her. But some on the Republican side say they have also been angered by Mr Dickson’s actions, setting up the possibility that the search for a permanent FAA chief will have to start again.