Apollo 11's descent to the surface was, by far, the most challenging of all the missions because it was the first; and being the first, it tested procedures that could not otherwise be tested. Those procedures were found to be wanting, because soon after Eagle had yawed around and the landing radar had begun to feed data to the computer, Armstrong made an urgent call.
"It's looking good to us,'' said Duke in the Capcom seat referring to the data coming from the landing radar.
"It's a 1202,'' said Armstrong to inform Houston of the code that had come up on their DSKY. "What is it?'' he asked Aldrin. It was an error code from deep in the executive software, but neither of them had the foggiest notion what it meant. "Let's incorporate,'' he added, having heard Duke's comment that the landing radar data was good. "Give us a reading on the 1202 program alarm,'' Armstrong called to Houston some 15 seconds after the alarm had occurred.
The Guido flight controller, Steve Bales, was responsible for the LM's guidance. He and his back room team knew the LM's programming well, and did know what the alarm meant. The computer was reporting that it was overloaded, but Bales could tell from his telemetry that it was managing its primary tasks. So long as the error did not become continuous, it would be able to cope. Armstrong was told that he should continue the powered descent.
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