How a single line of #code brought down a half-billion euro #rocket launch

"So what was the ultimate cause of this very short, very expensive and catastrophic flight? A line of code converting a 64-bit floating point to a signed integer, which led to an #overflow passed directly to the main #computer, that interpreted it as real data.
The same #software was designed and used successfully on many flights previously, on the #Ariane 4 rockets, which were much smaller. But the new Ariane 5 model was designed to fly faster than the #systems engineers had planned when that code was originally created.
That same higher velocity led to the overflow error, which could have been caught easily. But it wasn’t.
The worst part? The code wasn’t necessary after takeoff, it was only part of the launch pad alignment process. But sometimes a trivial glitch might delay a launch by a few seconds and, in trying to save having to reset the whole system, the original software engineers decided that the sequence of code should run for an extra… 40 seconds after the scheduled liftoff."

https://jam.dev/blog/famous-bugs-rocket-launch/