American Eagle Flight 4184 icing crash
An ATR 72 turboprop crashed near Roselawn, Indiana, after an uncommanded roll in icing conditions, killing all 68 people aboard.
The damage was public. The root cause was preventable.
An ATR 72 turboprop crashed near Roselawn, Indiana, after an uncommanded roll in icing conditions, killing all 68 people aboard.
What the software actually got wrong
Ice accumulation on the wings created an aileron hinge-moment reversal, but the autopilot compensated for the developing roll tendency without alerting the crew, masking the deteriorating condition until the autopilot's control authority was exceeded and it abruptly disconnected, leaving the crew with no warning before loss of control.
Ice accumulation on the wings created an aileron hinge-moment...
Ice accumulation on the wings created an aileron hinge-moment reversal, but the autopilot compensated for the developing roll tendency without alerting the crew, masking the deteriorating condition until the autopilot's control authority was exceeded and it abruptly disconnected, leaving the crew with no warning before loss of control.
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.
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.
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.
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.
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