Program alarms: part II

Apollo 11 had already had a brief encounter with the computer throwing out program alarms during the braking phase. As Armstrong and Aldrin brought Eagle through the approach phase, the computer began to play up again.

“Eagle, Houston. You’re Go for landing.” said Duke in the Capeom chair.

“Roger. Understand. Go for landing. 3,000 feet,” returned Aldrin, as they passed

1.0 metres altitude.

“Copy,” said Duke.

Just then. Aldrin called. “Program alarm. 1201.”

“1201." repeated Armstrong, then to Aldrin, “Okay, 2,000 at 50." They were 700 metres up, still flying forward and descending at 15 metres per second. The program alarm was distracting both crewmen from their practised tasks, with Armstrong looking at the DSKY for information instead of looking out of the window’.

Jack Garman was part of Bales’ backroom team watching over the guidance equipment. When the first alarm occurred, he had looked at a hand-written list of codes which told him what they all meant. Like Bales, he was spring-loaded to respond to these alarms, if they happened. Garman later described the moment when the second alarm appeared and how he passed on his opinion of the alarm code.

“When it occurred again a few’ minutes later, 1 remember distinctly yelling – by this time yelling, you know, in the loop here – ’Same type!’ and [Bales] yells, ‘Same type!" I could hear my voice echoing.” laughed Garman. "Then the Capeom says, ‘Same type!’ Boom, boom, boom, going up. It was pretty funny.”

“Give me an LPD,” asked Armstrong, his eyes back out of the window’ again. He wanted to know where the computer w-as taking them.

“Into the AGS, 47 degrees,” Aldrin was working the secondary computer, the abort guidance system, as well as feeding numbers to Armstrong.

“47,” replied Armstrong. “That’s not a bad looking area. 1,000 at 30 is good. Wh at s LPD’ he asked Aldrin again. Armstrong didn t realise that the LPD was being interfered with by the propellant sloshing about in the tanks. As the great weights of liquid moved from side to side, they altered the LM’s attitude enough to set the RCS thrusters into excessive activity trying to correct it. The computer, with its 2-second cycle time could not keep up with the attitude excursions.

“Eagle, looking great,” said Duke from mission control. "You’re Go.” Then when another alarm appeared, he confirmed that the flight controllers were seeing it also. “Roger. 1202. We copy it."