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Letter to Congress on FAA’s Oversight of the Boeing 737 MAX Angle-of-Attack Disagree Alert and the Maneuvering Characteristics Augmentation System

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Requested by the Chairmen of the House Transportation and Infrastructure Committee and its Subcommittee on Aviation
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We issued a letter to the House Transportation and Infrastructure Committee and its Subcommittee on Aviation in response to a request that we review the Federal Aviation Administration’s (FAA) oversight of two key areas on the Boeing 737 MAX aircraft. Our objectives were to evaluate FAA’s oversight activities of two targeted elements of the 737 MAX: (1) the inoperability of the angle-of-attack (AOA) disagree alert on the majority of the MAX fleet in 2019 and (2) the inclusion of the maneuvering characteristics augmentation system (MCAS) as part of the speed trim in the 737 MAX design. Specifically, we evaluated FAA’s compliance with applicable statutes, regulations, and policies in overseeing Boeing’s actions concerning those two areas. Given the extensive nature of our prior reports related to FAA’s oversight and certification of the 737 MAX, we transmitted the results of this review via letter as our work did not result in additional findings or recommendations for action to FAA.
We found that while Boeing followed its internal guidance in classifying the AOA disagree issue as “non-safety,” and FAA subsequently concurred with Boeing’s assessment, there were problems with communication between Boeing and FAA. FAA and Boeing have since taken action to resolve many of these weaknesses, including issuing new guidance and procedures relating to classifying and tracking problem reports. However, it is unlikely that these changes would have resulted in a different safety/non-safety determination regarding the AOA disagree alert issue. Regarding MCAS, as we reported in June 2020, Boeing originally presented MCAS as part of the aircraft’s existing speed trim system in 2012, and as a result, MCAS did not receive much scrutiny during the original certification process. While FAA had the authority to investigate Boeing or individual unit members for this presentation after learning of its existence in 2019, Agency officials chose not to do so. During this time, FAA continued to focus on the task of evaluating the MAX flight control system, including MCAS, and returning the airplane to service, while deferring to the Department of Justice and DOT Office of Inspector General to investigate.