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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: 0.218s | source
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benrutter ◴[27 Aug 25 08:18 UTC] No.45036836[source]▶
> software quality doesn't appear because you have good developers. It's the end result of a process, and that process informs both your software development practices, but also your testing. Your management. Even your sales and servicing.

If you only take one thing away from this article, it should be this one! The Therac-25 incident is a horrifying and important part of software history, it's really easy to think type-systems, unit-testing and defensive-coding can solve all software problems. They definitely can help a lot, but the real failure in the story of the Therac-25 from my understanding, is that it took far too long for incidents to be reported, investigated and fixed.

There was a great Cautionary Tales podcast about the device recently[0], one thing mentioned was that, even aside from the catasrophic accidents, Therac-25 machines were routinely seen by users to show unexplained errors, but these issues never made it to the desk of someone who might fix it.

[0] https://timharford.com/2025/07/cautionary-tales-captain-kirk...

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1. credit_guy ◴[28 Aug 25 00:15 UTC] No.45046867[source]▶
I'm not sure. Most software (by orders of magnitude) is not critical software like the software running that X-ray machine. In general, if your software fails, a page loads too slow, or a report comes with lots of NaN's, or some batch job does not run at the right time, and someone needs to start it manually, etc. The cases where someone dies because of a software quality issue are very rare, and the developers working on that type of software know who they are and what their duties are (I hope).