This story has a solid core. On November 14, 1969, the Apollo 12 mission’s Saturn V rocket was hit by lightning twice within its first minute. The spacecraft’s telemetry system became chaotic, but a flight controller named John Aaron managed to turn things around. He recognized a fault pattern that few people understood and called for a switch that was equally obscure.
Aaron was the mission’s EECOM that day, responsible for the spacecraft’s electrical, environmental, and communication systems. He wasn’t very senior—just a few years into his NASA career—which is crucial to the story. His success relied more on his knowledge than on any rank.
What actually happened during the strikes
NASA reported that the first lightning strike occurred 36.5 seconds after lift-off, while the rocket was about 6,000 feet up. A second strike hit roughly 52 seconds in. The rocket, ascending through an electrically charged weather system, likely created the path that triggered the lightning, completing a circuit rather than merely being struck by a storm.
The effects inside the spacecraft were immediate: three fuel cells went offline, warning lights on the command module lit up, the guidance platform lost its reference, and telemetry data became virtually useless. As commander Pete Conrad reported after the second strike, “OK, we just lost the platform, gang. I don’t know what happened here; we had everything in the world drop out.” Back on the ground, flight director Gerry Griffin feared he might need to abort the mission.
Why Aaron saw the pattern
What set Aaron apart was a bit of curiosity from a previous year.
During a test at Kennedy Space Center, he had noticed unusual telemetry readings and, taking the initiative, traced them back to a unit called the signal conditioning equipment (SCE). This equipment converted raw sensor data into usable voltages for telemetry. Aaron realized that, under low-voltage conditions, it emitted a distinctive signature of nonsense—something he recognized when Apollo 12’s telemetry collapsed.
So when telemetry failed, Aaron wasn’t looking at random malfunctioning. He understood the pattern: the lightning caused a voltage drop; the SCE was misbehaving as low voltage affected it, and the data wasn’t truly lost—just coded incorrectly.
The obscure switch
Aaron suggested to the flight director four simple words: “Try SCE to auxiliary.” This auxiliary setting would keep the unit operational even at low voltage, allowing telemetry to be restored and enabling controllers to assess the spacecraft’s condition.
Most people in the room didn’t recognize the instruction. Griffin was unfamiliar with the switch, and astronaut Gerald Carr had to ask Aaron to repeat it, exclaiming, “What the hell’s that?” Nonetheless, Carr relayed the instruction to the crew. Fortunately, lunar module pilot Alan Bean had a grasp on where the obscure switch was, found it, and flipped it. This action restored telemetry, which allowed them to bring the fuel cells back online and begin evaluating the situation. This episode is how Aaron earned the nickname “steely-eyed missile man.” Even fifty years later, NASA’s Apollo Flight Journal looks back at this event in detail.
What the simplified version omits
This story is frequently condensed to one switch saving one mission, which simplifies a much longer process.
Restoring telemetry didn’t instantly fix the spacecraft; it only let them see what was wrong. The fuel cells had to be manually activated, and the guidance platform, which had lost its orientation, needed to be realigned—a step performed later when Apollo 12 was in Earth orbit. The decision to proceed to the Moon wasn’t made while Aaron was at his console; it was confirmed once the vehicle reached orbit and systems were verified, leading to the “Go for TLI” call. Aaron’s actions were pivotal, but reducing it to “just one switch” minimizes the entire chain of recovery.
It’s also important to understand that recognition alone isn’t sufficient. Aaron’s ability to identify the pattern mattered because Bean acted on his suggestion. If no one on the spacecraft knew how to execute the correct call, it would have been useless.
The lasting impact wasn’t just that phrase. In February 1970, an investigation into the Apollo 12 incident concluded the vehicle and its exhaust plume likely triggered the strikes by creating a conduction path through the storm, a possibility not previously considered. Consequently, NASA revised its launch weather policies, prohibiting launches through cumulonimbus clouds and at specific distances from thunderstorms. This change, rather than the switch itself, ensured future flights wouldn’t rely on an individual’s prior curiosity.
