Columbia

Our military is supposed to (in between bouts of self-flagellation) make plans for defending against and defeating enemies known and potential. I'm told we entered a world war with a North Atlantic naval plan in the safe to fight Britain, but not Germany. Somebody fell down on the job.

One of my favorite scenes (at the time) from movie Marooned was the supervisor explaining that the checklist was going to take too long to make the deadline, and the manager taking the checklist book from him and throwing it away and announcing that "We're going to find out if the redundant systems work." Or words to that effect; I decline to try to find and re-watch it to get it exact

Since then I've been part of starting complicated systems myself, and seen from afar how regularly NASA hits glitches in its countdowns--not infrequently serious enough to demand delays. No, you can't skip the checklists; and sometimes A, B, and C have to be done sequentially.

Ars Technica has a very interesting article (updated from 2014) on whether Columbia's crew could have been saved by sending up Atlantis.

Maybe. If there were no major glitches (fuel valve issues are what I remember as most common). If the last CO2-poisoned astronauts could have donned the complex spacesuit successfully. If Atlantis didn't have foam damage too. (NASA had had 6 foam incidents before.) If NASA already had a plan in the safe.

For the rest of the shuttle flights (except the last), they did.

One of my responsibilities for some years was the backup of our servers. We spent a fair bit of money on it, and it took a little time, but I can count on the fingers of one hand the number of times we needed the system--and just as many incidents where people wrote to areas they were warned weren't backed up. I also had a role in disaster planning--and of course the disaster we had wasn't one of those we'd planned for (we couldn't afford the necessary redundancy anyway). Disaster planning feels a bit like make-work, especially when nothing bad happens. It's an easy expense to put off for another fiscal year, and "something went weird with the kubernetes servers this morning" too.

I suppose you can fail in the other direction too--creating new bureaucracies to be ready for an ever-expanding list of potential problems. And they'll each itch to justify their existence by spotting their target problem under every rug. Oh well.