... That was her 27th successful flight. ... Columbia was in the flight regime where pitch RCS activity was nominally deactivated, although yaw control was the domain of the RCS. ... From general principles, even without a sophisticated model, one can conclude that in a wing separation event, Columbia would have yawed to the right (reduced left wing area producing drag) and begun rolling to the left. ... Left yaw, right roll, pitch up. right rear RCS thrusters fire to counteract left yaw. ...