Boeing concealed crucial information from the FAA and pilots and made faulty assumptions about a flight control software fix called MCAS related to the two deadly 737 MAX crashes, according to preliminary investigative findings by U.S. House staffers.
The 13-page report, issued Friday by Democratic staff for the House Committee on Transportation, arrived just days before the March 10 anniversary of the 2019 Ethiopian Airlines crash that killed 157 people, including eight Americans. The first crash killed 189 passengers and crew aboard a Lion Air flight on Oct. 29, 2018.
The report also focuses on production pressures on Boeing engineers that jeopardized safety, Boeing’s influence over the Federal Aviation Administration oversight that led FAA managers to reject safety concerns, and inherent conflicts of interest with Boeing workers who are authorized to perform certification work on behalf of the FAA.
The committee is continuing to investigate the crashes and has been performing its work for nearly 12 months with five public hearings, testimony from more than a dozen witnesses and review of 600,000 pages of documents. “There are a number of leads we continue to chase down to better understand how the system failed so horribly,” said Chairman Peter DeFazio, D-Oregon, in a statement. He and Chairman Rick Larsen, D-Washington, plan to introduce legislation to address failures in the 737 MAX certification process in coming weeks.
“It [is] abundantly clear Congress must change the method by which the FAA certifies aircraft,” Larsen said in a statement.
In a short response, Boeing said via email that it would review the preliminary report, noting that it has “cooperated extensively.”
The FAA said in a statement provided to FierceElectronics that it welcomed the preliminary report and defended the “unprecedented” U.S. aviation safety record “built on the willingness of aviation professionals to embrace hard lessons and to seek continuous improvement.” It said the lessons learned from the crashes will be a “springboard to an even greater level of safety,” and added: “We are a learning agency and welcome the scrutiny.”
While the report’s focus on MCAS (Maneuvering Characteristics Augmentation System) software is just one of five major areas of the ongoing investigation, it was pivotal in the crashes.
“Based on incorrect assumptions, Boeing permitted MCAS—software designed to automatically push the plane’s nose down in certain conditions—to rely on a single angle of attack (AOA) sensor for automatic aviation and assumed pilots, who were unaware of the system’s existence in most cases, would be able to mitigate any malfunction,” the report says. “…Boeing failed to classify MCAS as a safety-critical system, which would have offered greater scrutiny during its certification. The operation of MCAS also violated Boeing’s own internal design guidelines established during development.”
In describing a “culture of concealment” at Boeing, the report notes that Boeing withheld crucial information from the FAA and pilots which “included hiding the very existence of MCAS from 737 MAX pilots and failing to disclose that the AOA disagree alert was inoperable on the majority of the 737 MAX fleet…This alert notified the crew if the aircraft’s two AOA sensors disagreed, an event that occurs only when one is malfunctioning.”
The report adds that Boeing failed to classify MCAS as a safety-critical system and “sought to diminish focus on MCAS as a new system in order to avoid greater FAA scrutiny and increased pilot training.” Boeing employees avoided FAA certification in 2013 by describing MCAS as “an addition to [the existing] Speed Trim [system]. The House investigators found a Boeing email from a meeting that warned: “If we emphasize MCAS is a new function there may be greater certification and training impact.”
In 2015, the report adds, a Boeing AR (Authorized Representative, an employee assigned to represent the interests of the FAA in validating an aircraft in compliance with FAA requirements) raised the question of whether MCAS was vulnerable to a single AOA failure but the aircraft was still delivered with MCAS dependent on a single AOA sensor.
And In 2016, the report continues, Boeing sought and received FAA approval to remove references to MCAS in the Boeing Flew Crew Operations Manual, ensuring that pilots wouldn’t know about the software and its impact on aircraft handling.
The report adds that the AOA Disagree alert was tied to an optional display indicator and was therefore not functioning on 80% of the fleet. Boeing chose to implement a software update in 2020, three years later, rather than implement it as soon as possible. And Boeing didn’t acknowledge that the AOA Disagree alerts weren’t operational until after the Lion Air crash in October 2018.
The report also notes that Boeing—out of economic considerations—evaded pilot training requirements necessitated in the event of MCAS activations.
“Boeing’s design and development of the 737 MAX was marred by technical design failures, lack of transparency with regulators and customers and efforts to obfuscate information about the operation of the aircraft,” the report concludes. “During the development of the 737 MAX, Boeing engineers raised safety concerns about MCAS being tied to a single AOA sensor.”
Boeing has since agreed to have two sensors feed into MCAS and now recommends pilot simulator training on the 737 MAX before it returns to service. But Boeing’s reactions to safety concerns “have consistently been too late,” the report concludes.
Because multiple technical design and certification problems were found compliant by the FAA, there is a need for regulatory reforms that serve to “highlight an aviation oversight system in desperate need of repair,” the report concludes.