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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: 0.345s | 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!
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NitpickLawyer ◴[27 Aug 25 08:23 UTC] No.45036858[source]▶
The MCAS related bugs @ Boeing led to 300+ deaths, so it's probably a contender.
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solids ◴[27 Aug 25 08:26 UTC] No.45036870[source]▶
Was that a bug or a failure to inform pilots about a new system?
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AdamN ◴[27 Aug 25 08:33 UTC] No.45036913[source]▶
Both - and really MCAS was fine but the issue was the metering systems (Pitot tubes) and the handling of conflicting data. That part of the puzzle was definitely a bug in the logic/software.
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1. phire ◴[27 Aug 25 09:30 UTC] No.45037262[source]▶
That wasn't a bug.

They deliberately designed it to only look at one of the Pitot tubes, because if they had designed it to look at both, then they would have had to implement a warning message for conflicting data.

And if they had implemented a warning message, they would have had to tell the pilots about the new system, and train them how to deal with it.

It wasn't a mistake in logic either. This design went through their internal safety certification, and passed.

As far as I'm aware, MCAS functioned exactly as designed, zero bugs. It's just that the design was very bad.