Boeing (BA) officials “inappropriately coached” test pilots during recertification efforts to get the aircrafts back in the air, a US congressional report has concluded.
The report released on Friday by the Senate Commerce Committee raised questions about testing in 2020 of a key safety system known as MCAS tied to both fatal crashes, which prompted the planes to nosedive shortly after take-off.
It also said that the US aviation regulator, the Federal Aviation Administration (FAA) and Boeing officials “had established a pre-determined outcome to reaffirm a long-held human factor assumption related to pilot reaction time.”
“It appears, in this instance, the FAA and Boeing were attempting to cover up important information that may have contributed to the 737 Max tragedies,” the committee said.
Boeing’s 737 Max planes were grounded in March 2019 following two deadly crashes that killed 346 people.
The planemaker said on Friday that it takes “seriously the committee’s findings and will continue to review the report in full.”
Boeing added: “We have learned many hard lessons from the Lion Air Flight 610 and Ethiopian Flight 302 accidents, and we will never forget the lives lost on board. The events and lessons learned have reshaped our company and further focused our attention on our core values of safety, quality, and integrity.”
The FAA it was “carefully reviewing the document, which the committee acknowledges contains a number of unsubstantiated allegations.”
The regulator added that the committee's report contained "a number of unsubstantiated allegations.” and that its review of the 737 Max had been thorough. It said it was confident that safety issues with the aircraft had been addressed.
The Senate Commerce Committee report cited a whistle-blower who claimed that Boeing officials prompted test pilots to use a particular control immediately before an exercise.
It comes after the FAA cleared 737 Max aircrafts to fly again after being grounded for 20-months, in November,
The regulator said existing planes would need to be modified before going back into service, with changes to their design, while pilots would need retraining. It said the design changes it had required had "eliminated what caused these particular accidents.”
Boeing 737 Max flights have already resumed in Brazil. The first US 737 Max — an American Airlines (AAL) commercial flight with paying passengers is set for 29 December.
Similarly, the European Union Safety Agency’s (EASA) top regulator said the aircraft is safe to fly, following changes to the design of the jet, also in November.
In September, a review kicked off in London which aimed to return the beleaguered aircraft to the skies.
A multi-agency effort saw civil aviation authorities and airline flight crews from the US, EU, Canada and Brazil “review Boeing’s proposed training” for 737 Max flight crews.
Following the grounding of the jetliner, the company swung to a $636m (£498m) annual loss in January 2020 — its first loss in more than 20 years — Boeing put the total costs of the grounding at $19bn.
Boeing suspended new deliveries of the plane, following the biggest crisis in its 103-history. The US manufacturing giant also set aside a further $9.2bn to cover the costs of airlines that cancelled 737 Max flights and towards higher costs related to compensation.
The crisis, led to the firing of chief executive Dennis Muilenburg, caused layoffs at suppliers and put Boeing behind rival Airbus (AIR.PA) in sales and deliveries of new jetliners.
Watch: Boeing takes back to air