Boeing 737 MAX: What Investigators Found Before and After the Second Crash
Boeing 737 MAX: How MCAS, Certification and Organisational Failures Contributed to Two Fatal Crashes
In 2018 and 2019, Boeing suffered two horrific crashes resulting in the loss of 346 lives. The crisis cost Boeing more than $20 billion in direct costs and wiped $55 billion from its market cap. Investigators discovered the aircraft was fighting its own pilots — a hidden software system called MCAS was forcing the nose down, and pilots had no idea it existed.
What Happened
On 29 October 2018, Lion Air Flight 610 plunged into the Java Sea 13 minutes after take-off, killing all 189 people on board. Less than five months later, on 10 March 2019, Ethiopian Airlines Flight 302 crashed six minutes after departure from Addis Ababa, killing 157 more. Both aircraft were brand-new Boeing 737 MAX 8s. Both went into the same fatal dive. The connecting factor was MCAS — the Maneuvering Characteristics Augmentation System. Boeing had installed it to counter the pitch-up tendency created by the MAX's larger, forward-mounted engines at high angles of attack, so the MAX would handle like earlier 737s. But MCAS relied on a single angle-of-attack sensor. When that sensor fed wrong data, MCAS repeatedly pushed the nose down into an unrecoverable dive. The most chilling part: pilots were never told MCAS existed. Boeing had hidden it to avoid costly retraining. The FAA delegated certification oversight to Boeing employees. And congressional investigators concluded that the hard questions were never asked at the top of the company. It was a cascade of failures at every level of governance — and 346 people paid the price.
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Frequently Asked Questions
MCAS was a central factor in both crashes. Accident investigations identified MCAS design, erroneous angle-of-attack sensor inputs, certification assumptions, training and other contributing factors.
The crisis cost Boeing over $20 billion in direct costs including aircraft grounding, production halt compensation to airlines, victim settlements, and regulatory fines. The reputational damage was incalculable.
Multiple failures across the chain: Boeing executives prioritised cost and schedule over safety, the FAA delegated too much oversight to Boeing itself, and the board failed to ask critical questions about the MCAS system.
MCAS was a software system designed to automatically push the nose down when the aircraft was at risk of stalling. It relied on a single sensor and could activate repeatedly if that sensor fed it false data — which is exactly what happened in both crashes.
Never hide operational changes from end-users. Compliance teams must have independent veto power. Shortcuts in training and documentation, taken to meet deadlines, create catastrophic technical debt. Engineering integrity must always override commercial pressure.
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