sail

This occurs when the Shuttle flight software goes through
rigorous testing as part of its final verification prior to
flight. It is also used to test the performance of new flight
avionics hardware prior to installation in the Shuttle. It is a
high fidelity simulator that uses many flight hardware avionics
components. Testing often encompasses functionality checks for
all avionics subsystems of each Shuttle element - the Orbiter
vehicle, external tank, main engines, and solid rocket
boosters. At a minimum, a standard set of verification tests is
performed prior to each flight to ensure mission success.