Nov. 14, 1969: Apollo 12 was struck by lightning twice within a minute after liftoff, disabling instruments and knocking out the guidance platform. Flight controller John Aaron, recalling a simulator lesson, told the crew to switch the signal conditioning equipment ("SCE") to auxiliary power. That single command restored telemetry and allowed the mission to continue; five days later Conrad and Bean landed on the Moon. NASA later tightened launch-weather rules to reduce lightning risk.
How a Single Switch Saved Apollo 12 After Two Lightning Strikes
Nov. 14, 1969: Apollo 12 was struck by lightning twice within a minute after liftoff, disabling instruments and knocking out the guidance platform. Flight controller John Aaron, recalling a simulator lesson, told the crew to switch the signal conditioning equipment ("SCE") to auxiliary power. That single command restored telemetry and allowed the mission to continue; five days later Conrad and Bean landed on the Moon. NASA later tightened launch-weather rules to reduce lightning risk.
01:55 AM, 11/15/2025Science
How a Single Switch Saved Apollo 12 After Two Lightning Strikes
On Nov. 14, 1969, the Apollo 12 Saturn V rocket lifted off from Kennedy Space Center and, within a minute, was struck by lightning twice — yet the mission continued on to the Moon. The near-disaster is one of NASA's most dramatic examples of quick thinking, training and human ingenuity overcoming a frightening in-flight emergency.
The sequence: Thirty-six seconds after liftoff the rocket was hit by lightning, which triggered a cascade of alarms and made it appear to the crew that electrical power generation and distribution had failed. While the astronauts were reacting, a second strike came just 16 seconds later and knocked out the guidance platform. Commander Charles "Pete" Conrad radioed, "OK, we just lost the platform, gang. I don't know what happened here; we had everything in the world drop out."
The fix: Flight controller John Aaron at Mission Control in Houston remembered a similar failure from simulator training. Aaron instructed the crew to switch the signal conditioning equipment (SCE) to its auxiliary power position — the now-famous instruction often abbreviated as "SCE to Aux." After that single action, onboard telemetry and instrumentation began reporting normally and the vehicle's systems recovered.
Despite the early scare, Apollo 12 continued its mission. Five days later, on Nov. 19, 1969, Commander Conrad and Lunar Module Pilot Alan Bean landed the lunar module on the Moon while Command Module Pilot Richard F. Gordon Jr. remained in lunar orbit. The mission successfully performed its scientific objectives, including near-Surveyor 3 exploration.
Legacy: The Apollo 12 lightning strikes prompted NASA to review and tighten launch-weather rules to reduce the risk of launching when atmospheric conditions could produce lightning. The episode remains a celebrated example of the value of simulator training, experienced flight controllers and decisive action under pressure.
Quick fact: The terse but decisive call "SCE to Aux" became a legendary line in NASA history and highlighted how one well-trained controller saved a multimillion-dollar crewed mission.