Eastern Air Lines Flight 401 crash
An L-1011 crashed into the Florida Everglades while the crew was distracted troubleshooting a landing gear indicator light, killing 101 of the 176 people aboard.
The damage was public. The root cause was preventable.
An L-1011 crashed into the Florida Everglades while the crew was distracted troubleshooting a landing gear indicator light, killing 101 of the 176 people aboard.
What the software actually got wrong
A slight, inadvertent nudge of the control yoke disengaged only the altitude-hold function of the autopilot, with no distinct warning to alert the crew that the aircraft had begun a slow, unnoticed descent while their attention was elsewhere.
A slight, inadvertent nudge of the control yoke disengaged...
A slight, inadvertent nudge of the control yoke disengaged only the altitude-hold function of the autopilot, with no distinct warning to alert the crew that the aircraft had begun a slow, unnoticed descent while their attention was elsewhere.
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.
Schedule a demonstration, or explore how Requs AI Edge Case and Software FMEA use the Common Defect Enumeration.
See real failures this would have caught
Failures like this one can be found before release. See how Requs AI finds them early:
- Software FMEA tool — find failure modes and root causes before code ships
- Software reliability prediction — predict defects before code is written (IEEE 1633)
- Software risk assessment checklist — spot the risks behind failures like this