Competing blunder: the float-to-16bit-signed-integer-conversion bug which caused the destruction of Ariane 5 in 1996: alas, the resulting number was higher than 2**15, so the steering system collapsed and transfered control to the secondary system which ran into the same bug...

some facts:

• the bug was triggered 36.7 seconds after start
• it was Ariane 4 software, but Ariane 5 was faster
• the software containing the bug wasn't used at all in the flight, it was only used at countdown. To enable a fast reset the software was scheduled to be active for 40 seconds after start
• primary and backup computer systems had identical software
• the casting hasn't been harnessed, because nobody thought an overflow was possible