Apollo Guidance Computer History Project

Second conference

September 14, 2001

Trust in Automatic Systems

JIM MILLER: You asked about trust in automatic systems. I remember just a short anecdote: We were visited at the Laboratory one day by John Glenn and Alan Shepard and I think a third astronaut. It was at the time when reporters were still chasing around after the seven astronauts - it was a big thing when the astronauts were coming. The Laboratory was showing those folks what we were doing.

And one of the things that, at the time, we had the arrogance to believe we should do was to make sure that nothing could be done by the crew that would endanger them. So there were a lot of tests in the software that said, if the delta V is in the wrong direction or this or that, then they couldn't execute the proceed order to go ahead because the software thought something was wrong. I remember two things that Shepard, with his marvelous way with words, said. On this one he said, "You guys think you know more about what is going to face us during flight than we will know during the flight. You're wrong." He said, "Take all of those lockouts out. If we want to kill ourselves, let us. We may be saving ourselves." Of course he was right. And I think everybody sort of woke up to that. That made the software a lot easier too (laughter) because we did not have to worry about all those checks.

DAN LICKLY: It did let him start the prelaunch program on the back from the moon.

JIM MILLER: They weren't capable of perfection. But they were pretty well trained, and they certainly were motivated.

DAN LICKLY: They were very well trained. I will say that. But they also got very tired. I had the re-entry which is at the end of five days out there. And they swore through all the early years that they were going to fly it manually. As far as I know, none of them ever touched a manual stick. They were so beat. And then all of a sudden you hit 7 Gs. I'm not sure they could even see what was going on by then. They didn't get any sleep out there for all that time. I'm surprised they were doing as well as they did after all that time.

MARGARET HAMILTON: We had a different opinion of this subject matter than the astronauts did. At least the software group did at the time this took place, the prelaunch. We talked about that the last time, in our last meeting -- when the astronauts selected prelaunch during flight. So I think there's sort of an in-between, you don't want to overdo it but you also want to make the crucial areas safe so you won't have a catastrophe.

JIM MILLER: Shepard, in that meeting, was responsible, I think, for the demise of another thought that we had had, which was since the computer was not being perfectly reliable - it was going to be necessary to do in-flight repairs. So there were a lot of thoughts about diagnosing what had gone wrong, changing AGC modules and so forth. I don't know how far along that got. But Shepard's comment on that was, "yeah, and we should all train to be brain surgeons so we can operate on each other." I think that was the end of in-flight repair.

Introduction of project management methods

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