Comment 50% Chance (Score 1) 211
Armstrong: "I thought we had a 90% chance of getting back safely to Earth on that flight but only a 50-50 chance of making a landing on that first attempt. There are so many unknowns on that descent from lunar orbit down to the surface that had not been demonstrated yet by testing and there was a big chance that there was something in there we didn't understand properly and we had to abort and come back to Earth without landing."
Seems like a decent estimate. The landing computer had issues that almost was cause for an abort. I'm surprised NASA decided to ignore the alarm. Who wants to try to land with an active error code? Two even. In hind-site it was the correct decision, but the cause was unknown at the time.