The Boeing 737 MAX was designed as an answer to intensifying competition in the global passenger aircraft market. The plane became a huge commercial success — until two nearly new 737 MAX aircraft crashed just five months apart.

In October 2018, Lion Air Flight 610 crashed into the Java Sea in Indonesia. In March 2019, Ethiopian Airlines Flight 302 crashed shortly after taking off from Addis Ababa. A total of 346 people were killed in the two disasters.

PBS’s investigative journalism series FRONTLINE examines the chain of events behind the crashes in Boeing’s Fatal Flaw. The documentary investigates Boeing’s design decisions, the commercial pressures facing the company, and the oversight of the U.S. Federal Aviation Administration (FAA).

At the center of the story is the MCAS flight-control system. The system was designed to affect the aircraft’s behavior under certain flight conditions, but faulty sensor data could cause it to repeatedly push the nose of the aircraft downward. Documents later examined during a congressional investigation revealed that concerns about the system had already emerged within Boeing during the aircraft’s development.

The documentary also explores a broader question: what happens when commercial goals, tight schedules, and regulatory oversight collide in an industry where safety is critical?

FRONTLINE originally released the documentary in 2021. This updated version, released in March 2024, also covers the January 2024 Alaska Airlines incident in which a door-plug panel blew out of a 737 MAX 9 during flight.

The documentary was directed by Tom Jennings and produced by FRONTLINE in collaboration with The New York Times and Left/Right Docs.