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The Therac-25 Incident (2021)

(thedailywtf.com)
449 points lemper | 1 comments | 27 Aug 25 06:57 UTC | HN request time: 0s | source
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napolux ◴[27 Aug 25 08:17 UTC] No.45036831[source]▶
The most deadly bug in history. If you know any other deadly bug, please share! I love these stories!
replies(8): >>45036858 #>>45036868 #>>45036872 #>>45036943 #>>45037179 #>>45037200 #>>45037786 #>>45038530 #
1. bobmcnamara ◴[27 Aug 25 12:07 UTC] No.45038530[source]▶
In Dhahran, Saudi Arabia, on February 25, 1991, a Patriot missile failed to intercept an Iraqi Scud causing the death of 28 American soldiers.

The patriot missile system used floating point for time, so as uptime extended the clock became more and more granular, eventually to the point where time skipped so far that the range gate was tripped.

The fix was being deployed earlier that year but this unit hadn't been updated yet.

https://www.cs.unc.edu/~smp/COMP205/LECTURES/ERROR/lec23/nod...