Boeing officials “inappropriately coached” test pilots during recertification efforts after two fatal 737 MAX crashes killed 346 people, a US congressional report has concluded.
The report by the Senate commerce committee raised questions about testing in 2020 of a key safety system known as MCAS tied to both fatal crashes.
The committee concluded 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 appeared that the “FAA and Boeing were attempting to cover up important information that may have contributed to the 737 MAX tragedies”.
The US grounded the 737 Max in March 2019 after two planes crashed because of faulty sensors and a design flaw that repeatedly pushed down the nose of the aircraft.
Friday’s report cited a whistleblower who alleged Boeing officials encouraged test pilots to use a particular control during an exercise, resulting in a pilot response time of around four seconds. Another pilot in a separate test reacted in approximately 16 seconds.
The account was corroborated during an FAA staff interview, the committee added.
Numerous reports have found Boeing failed to adequately consider how pilots respond to cockpit emergencies in its development of the 737 MAX.
Boeing said Friday it took the committee’s findings “seriously” and would “continue to review the report in full”.
The FAA said Friday it was “carefully reviewing the document, which the committee acknowledges contains a number of unsubstantiated allegations”.
The agency added it was “confident that the safety issues that played a role in the tragic [737 MAX] accidents involving Lion Air Flight 610 and Ethiopian Airlines Flight 302 have been addressed through the design changes required and independently approved by the FAA and its partners”.
The Senate commerce committee chairman, Roger Wicker, said the report included “significant examples of lapses in aviation safety oversight and failed leadership in the FAA”.
The committee also said “multiple independent whistleblowers contacted the committee to allege FAA senior management was complicit in determining the 737 MAX training certification level prior to any evaluation”.
Boeing resisted requiring simulator training for pilots before operating the 737 MAX but reversed course in January.
The report also noted Southwest Airlines was able to operate more than 150,000 flights carrying 17.2 million passengers on jets without confirmation that required maintenance had been completed.
The Senate report said the Southwest flights “put millions of passengers at potential risk”. Southwest said on Friday that it was aware of the report and added “we do not tolerate any relaxing of standards that govern ultimate safety across our operation”.
Boeing faces a continuing criminal probe into the MAX. The committee said its review was “constrained due to the continued criminal investigation”.
In November the FAA approved the 737 MAX’s return to service and flights have resumed in Brazil. The first US 737 MAX commercial flight with paying passengers is set for 29 December.