Apollo 12 Launch - Flight Directors Loop

Video from the channel lunarmodule5 about Apollo 12, linked on its Above Ten Thousand entry. Duration: 34:48. Language: English. Video type: Launch.

Audio of the Apollo 12 launch as heard on the flight director's loop at the Houston mission control, preceded by the countdown narration from the launch center. The real launch footage covers only the first 40 seconds; the rest of the ascent is illustrated with a recreation in an amateur space simulator, roughly synchronized.

The countdown runs through the final checks, the automatic sequence from T-3 minutes, pressurization of the Saturn V's tanks and the switch to internal power. Liftoff is announced at 11:22 a.m. Conrad reports clearing the tower and starting the pitch and roll program. Shortly after, the crew reports loss of the inertial platform, three fuel cell lights, fuel cell disconnect and AC bus overload. On the loop, the order to switch the SCE to auxiliary can be heard, after which telemetry becomes good again; Houston then asks to reset the fuel cells and the crew reconnects them. Conrad suggests they were struck by lightning.

With telemetry restored, the conversation among controllers focuses on the inertial platform, which is spinning uncontrolled. Without the platform there will be no S-IVB-to-orbit "go" call, and abort modes will depend on the backup system. There is discussion of whether to cycle the IMU power switch or open the IMU main A and main B circuit breakers on panel 5, and the crew is finally asked to open them and keep them open for at least three minutes.

Stage separation and S-IVB thrust are nominal; Houston confirms the spacecraft is exactly on its trajectory and that the launch vehicle's instrument unit is working flawlessly, and the crew jokes that so many lights were on they couldn't read them. After S-IVB shutdown, the spacecraft is left in a 102.5-by-100 orbit and gets the go-ahead to continue, with full realignment of the platform still pending.