S77-28136 (13 Sept 1977) --- The Orbiter 101 "Enterprise" is seen separating from the NASA 747 carrier aircraft during the second free flight of the Shuttle Approach and Landing Tests (ALTs) conducted on September 13, 1977 at Dryden Flight Research Center in Southern California. Astronauts Joe H. Engle, and Richard H. Truly were the crew of the "Enterprise." The ALT free flights are designed to verify Orbiter subsonic airworthiness, integrated systems operations and pilot-guided approach and landing capability and satisfying prerequisites to automatic flight control and navigation mode.