Boeing 737 MAX MCAS Software Failure Kills 346 People in Two Crashes
What happened
Two Boeing 737 MAX crashes — Lion Air 610 in October 2018 and Ethiopian Airlines 302 in March 2019 — killed 346 people. The MCAS flight control system repeatedly pushed the nose down based on a single faulty angle-of-attack sensor, overriding pilots who were unaware the system existed.[1]
What went wrong
MCAS was designed to rely on a single sensor with no redundancy. Pilots were not informed the system existed, let alone trained to counteract it. Boeing and the FAA certified MCAS under conditions that did not match its actual authority over the aircraft's flight path.[1]
Lesson learned
Safety-critical systems must have sensor redundancy. Pilots must be informed of all systems that can override their control inputs. Regulators and manufacturers must be independent — self-certification of safety systems creates catastrophic conflicts of interest.