Apollo abort modes
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During the course of the launch of an Apollo spacecraft by the Saturn V rocket there were several ways for the crew and computers to abort the flight. The method that would be used depended on how far into the flight the crew were. None of these abort modes were ever used.
- Mode One
- Alpha - During the first 42 seconds of flight up to 3000 metres, the Command Module (CM) would separate from the rest of the rocket propelled by the launch escape system (LES), with small solid fuelled engines at the top steering the capsule towards the east over the sea and away from the rocket. The tower would be jettisoned 14 seconds later and the hypergolic fuel on the CM would be automatically released.
- Bravo - From 3000 metres to 30.5 km, after the capsule had moved away from the rocket, canards would be deployed by the tower to force the CM-LES combination into a CM forward position
- Charlie - From 30.5 km until the LES is jettisoned just after S-II ignition, the CM reaction control system would be used to force the CM-LES combination into the CM forward position as the canards would have little effect in the now thin air.
- Two - After the LES is jettisoned, the Command/Service Module (CSM) would be separate as a whole from the rocket and either use its large engine or smaller control engines to separate from the rocket. The CM would then separate and perform a normal splashdown.
- Contingency Orbit Insertion (COI) - The S-IVB stage can now place the CSM on a trajectory such that the Service Module engine can now place the CSM into some sort of Earth orbit, but would not have sufficient propellant to continue onto the moon.
- S-IVB to orbit - The S-IVB can now place the CSM and LM into an Earth orbit, but it could not travel to the Moon.
- Mode Four - The Service Module engine now can place the CSM into Earth orbit should the S-IVB cut-off early.
