# In the Saturn V launch sequence, what defined COMMIT, and what happened between COMMIT and LIFTOFF?

With the Saturn V, there were two critical moments during launch that I am curious about:

1. The vehicle COMMITs to liftoff
2. The vehicle LIFTS OFF

LIFTOFF is fairly obvious: the booster has risen some small distance above the launch pad, and is basically on its way (but hasn't yet cleared the launch tower).

COMMIT was the point, a moment before LIFTOFF, at which the vehicle was committed to lift-off. In other words, no matter what else happened, it either rose from the launch pad, or things crashed and burned (and the LES likely saw use). Turning off the engines no longer caused it to settle back nicely on the pad with just a few tons less fuel than it had a few seconds earlier.

So much for pretext for my actual questions, which I believe to be highly related:

• What specific event or condition defined the COMMIT state of the vehicle? In other words, what caused the vehicle to become committed to lift-off, as opposed to not being committed to lift-off a moment earlier?
• What specific events, possibly limited to those visible to an ideal external observer (in the physics sense), occured in between COMMIT and LIFTOFF?

• So, COMMIT means "lifting off" and LIFTOFF means "yep, can confirm, that worked, we've got some separation here now boys". Aug 14 '16 at 19:55