Patriot missile system failure at Dhahran
A Patriot battery failed to intercept an incoming Iraqi Scud missile that struck a US Army barracks, killing 28 soldiers and injuring around 100 more.
The damage was public. The root cause was preventable.
A Patriot battery failed to intercept an incoming Iraqi Scud missile that struck a US Army barracks, killing 28 soldiers and injuring around 100 more.
What the software actually got wrong
A software rounding error in the system's internal clock calculation accumulated over the battery's long continuous run time (about 100 hours), causing its tracking gate to drift enough that it failed to recognize and intercept the incoming missile.
A software rounding error in the system's internal clock...
A software rounding error in the system's internal clock calculation accumulated over the battery's long continuous run time (about 100 hours), causing its tracking gate to drift enough that it failed to recognize and intercept the incoming missile.
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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