An F-16D taxis from the parking area at Edwards Air Force Base, Calif., for its final mission Sept. 30, 2010. Edwards AFB has operated Block 25 aircraft longer than any other Air Force base. Block 30, 40 and 50 F-16s have replaced the nearly 30-year-old Block 25 Fighting Falcons. The retired fighters are generally modified and sold to foreign militaries or are dismantled for parts. (U.S. Air Force photo/Greg L. Davis)