It never once had a failure in flight, except for the short in Apollo 14, which they managed to hack around mid-flight. Cool story: http://www.ibiblio.org/apollo/#Final_exam_for_the_advanced_s...

That was caused by an actual physical short (in space, conductive bits, usually soldier balls, floating around and shorting things was a big problem), which happened somewhat commonly. I think Apollo 12 nearly aborted the launch because the display was showing all 8s briefly, also caused by a short.

However there truly was never an unknown software bug discovered in flight. Lots of known software bugs had workarounds, partially because there was a hard deadline of about 4 months where the software couldn't be changed before the launch. Pretty amazing.

> Its popular to dismiss the AGC as simple and uninteresting, but it was a challenging engineering task, and it never once had a failure in flight.

Stating it never failed in flight is jumping the gun a bit, it didn't fly enough times to get a reliable statistic.

I would think it's accurate to state that the system never had a failure in flight if it never had a failure in flight, despite how many times it flew.

If you were to compare it to something else, then how many times it flew becomes important. For example, you can't necessarily say that a 100% success rate over 5 attempts is better than a 95% success rate over 100 attempts.

Right. I think I remember Digital Apollo quoting an engineer who estimated, based on their extensive ground testing, that the AGC had a MTBF of about 50,000 hours. That's not particularly good, but considering all the Apollo missions spent only about 1000 hours in space total, it was apparently good enough.

Digital Apollo is a great read.