Two Boeing 737 MAX crashes killed 346 people in less than five months: Lion Air Flight 610 on October 29, 2018, and Ethiopian Airlines Flight 302 on March 10, 2019. Investigators linked both accidents to repeated, uncommanded nose-down inputs from MCAS after faulty angle-of-attack sensor data. Boeing had obtained FAA permission in 2016 to remove MCAS references from pilot manuals, and pilots were not informed about the system until after the first crash. The FAA had privately estimated in December 2018 that an unrepaired MCAS problem could cause 15 crashes over 30 years.
The FAA initially defended the aircraft but grounded it on March 13, 2019, after other regulators acted; all 387 delivered aircraft were grounded by March 18. Congressional and Inspector General investigations found that Boeing prioritized deadlines, cost savings, minimal pilot training, and regulatory approval, while the FAA’s delegated-certification system weakened oversight. In January 2021, Boeing agreed to pay more than $2.5 billion in a DOJ fraud settlement, including a $243.6 million criminal fine, $1.77 billion for airline customers, and $500 million for victims’ families. The FAA ended the 20-month grounding on November 18, 2020, only after requiring redesigned MCAS safeguards, additional redundancy, direct FAA certification, and simulator training.