Free flight

The Enterprise flies over the Southern California desert. For the final two free flights, the tail cone--which had been used to minimize turbulence--was removed, since that would be the actual configuration on return from space. The final flight came to a close with a landing on the concrete runway at Edwards AFB, again simulating a return from an actual orbital mission; the landings for the previous four flights were on the Edwards dry lake bed.

NASA says that the fifth and final approach and landing test revealed a problem with the shuttle's flight control system that could have led to a dangerous situation called pilot-induced oscillation--a flaw corrected by further research.