The System Behind the 737 MAX Crisis

Two crashes, one system under scrutiny

Lion Air Flight 610 crashed in October 2018. Ethiopian Airlines Flight 302 crashed in March 2019. All 346 people aboard the two aircraft were killed. The disasters focused global attention on the Maneuvering Characteristics Augmentation System, or MCAS, part of the MAX flight-control architecture.

MCAS was intended to address handling characteristics in particular parts of the flight envelope. Investigators later examined how the original system could repeatedly command nose-down stabilizer movement based on input from a single angle-of-attack sensor, and how pilots had been informed and trained about the system.

The failure was larger than software

A 2020 U.S. House Transportation Committee majority-staff report described the crashes as the culmination of faulty technical assumptions, management transparency failures and insufficient FAA oversight. The report also examined production pressures and Boeing’s efforts to preserve commonality with earlier 737 models.

The Department of Justice later charged Boeing with conspiracy to defraud the FAA Aircraft Evaluation Group in connection with information about MCAS. In a 2021 deferred prosecution agreement, Boeing agreed to payments totaling more than $2.5 billion, including a criminal penalty, airline compensation and a fund for crash victims’ beneficiaries.

The enduring lesson is not that automation is dangerous. It is that safety depends on the entire system around the automation.

What changed afterward

Before the MAX returned to U.S. service, the FAA required design, software and training changes and conducted an extensive review. The episode also triggered changes in how certification, delegation and manufacturer oversight were discussed and regulated.

Reducing the crisis to 'bad software' misses the central lesson of the investigations. Complex systems fail through interactions: engineering assumptions, incentives, communication, training, regulation and organizational pressure can all meet in the same cockpit.