At six thousand feet above the lunar surface a yellow caution light came on and we encountered one of the few potentially serious problems in the entire flight, a problem which might have caused us to abort, had it not been for a man on the ground who really knew his job.

COLLINS: At five minutes into the burn, when I am nearly directly overhead, Eagle voices its first concern. "Program Alarm," barks Neil, "It's a 1202." What the hell is that? I don't have the alarm numbers memorized for my own computer, much less for the LM's. I jerk out my own checklist and start thumbing through it, but before I can find 1202, Houston says, "Roger, we're GO on that alarm." No problem, in other words. My checklist says 1202 is an "executive overflow," meaning simply that the computer has been called upon to do too many things at once and is forced to postpone some of them. A little farther along, at just three thousand feet above the surface, the computer flashes 1201, another overflow condition, and again the ground is superquick to respond with reassurances.

ALDRIN: Back in Houston, not to mention on board the Eagle, hearts shot up into throats while we waited to learn what would happen. We had received two of the caution lights when Steve Bales the flight controller responsible for LM computer activity, told us to proceed, through Charlie Duke, the capsule communicator. We received three or four more warnings but kept on going. When Mike, Neil, and I were presented with Medals of Freedom by President Nixon, Steve also received one. He certainly deserved it, because without him we might not have landed. (Ref. http://science.ksc.nasa.gov/history/apollo/apollo-11/apollo-11.html)