The F-117 Nighthawk, the world's first attack aircraft to employ stealth technology, is retiring after 27 years of U.S. Air Force service. The aircraft made its first flight at the Tonopah Test Range, Nev., in June 1981, just 31 months after full-scale development was authorized. The Nighthawk program remained classified until November 1988, when a photo of the jet was first unveiled to the public. (Air Force photo by Staff Sgt. Aaron Allmon II)