Three types of aircraft used as chase aircraft in support of research flights at NASA's Dryden Flight Research Center, Edwards, California, fly in formation over nearby mountains. They are, (bottom) the Lockheed F-104G, (upper left) the Northrop T-38A, and the McDonnell Douglas F/A-18A. Chase aircraft are flown by NASA pilots who accompany primary research aircraft in flight as safety observers, provide photographic coverage, and assist by radio and visually - when applicable - with various maneuvers and test points to be flown by the research pilot. Chase pilots are in constant communications with the research aircraft and the Dryden mission control room and serve as a backup ''set of eyes and ears'' to help the research pilot coordinate and conduct the research flights.