When a rocket launch is delayed or aborted late in the sequence, controllers must safely reverse the steps they just completed. This involves draining cryogenic propellants, safing pyrotechnics, and securing the vehicle. It is a highly scripted procedure designed to return the launch vehicle and pad to a stable, safe state.
Heard on the job
We lost the sensor feed at T-minus four minutes, so initiate the backout procedure and start draining the liquid oxygen.