Terminal countdown demonstration test
In the specific case of a TCDT for the Space Shuttle, the test culminated in a simulated ignition and RSLS Abort (automated shutdown of the orbiter's main engines).Following the simulated abort, the flight crew was briefed on emergency egress procedures and use of the fixed service structure slidewire system.[1] On some earlier shuttle missions, and Apollo missions, the test would conclude with the flight crew evacuating the launch pad by use of these emergency systems, but this is no longer part of the test.Unmanned carrier rocket launches also undergo TCDTs, when countdown procedures are followed.This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.