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Case Study #13 — Top 100 Software Failures

Boeing 737 MAX MCAS crashes and grounding

346 people died in two crashes (Lion Air 610 and Ethiopian Airlines 302); the entire 737 MAX fleet was grounded worldwide for about 20 months, costing Boeing over $20 billion.

2018-10-29 / 2019-03-10
When it happened
Aviation
Sector
#13 of 100
Ranked by documented impact
01 — What Happened

The damage was public. The root cause was preventable.

346 people died in two crashes (Lion Air 610 and Ethiopian Airlines 302); the entire 737 MAX fleet was grounded worldwide for about 20 months, costing Boeing over $20 billion.

Aviation
Sector affected
2018-10-29 / 2019-03-10
Date of the event
#13
Rank in the Top 100 Software Failures
1
Distinct root-cause clause identified below
02 — The Root Cause

What the software actually got wrong

The MCAS flight-control software relied on input from a single angle-of-attack sensor and could repeatedly command a strong nose-down trim on erroneous data, a design flaw compounded by inadequate crew documentation.

01Root Cause

The MCAS flight-control software relied on input from a...

What Happened

The MCAS flight-control software relied on input from a single angle-of-attack sensor and could repeatedly command a strong nose-down trim on erroneous data, a design flaw compounded by inadequate crew documentation.

How Requs AI Catches This

Requs AI Edge Case flags this exact pattern at the requirements and architecture stage — before a single line of code implementing it exists — so the assumption behind it gets challenged while it is still cheap to fix.

03 — How This Gets Caught Before It Happens

Beyond code coverage and "shall" testing

Root causes like this one rarely show up in code coverage or requirements-compliance testing, because nobody wrote a requirement anticipating the specific edge case that broke. Requs AI Edge Case and Requs AI Software FMEA are built to surface exactly this class of overlooked failure mode — before the software is written.

Requs AI Edge Case

Surfaces this before code exists

Identifies edge cases like this one at requirements and architecture time, using the Common Defect Enumeration to catalog failure patterns seen across hundreds of real-world software failures — including this one.

Requs AI Software FMEA

Connects the failure mode to the hazard

Traces this class of root cause directly to the system-level hazard it can produce, so a defect pattern like this one gets flagged during design review instead of after it ships.

Find the overlooked root causes before they ship.

Schedule a demonstration, or explore how Requs AI Edge Case and Software FMEA use the Common Defect Enumeration.