This air-to-air photograph shows a North American T-28 Trojan, serial number 13539, in flight above the clouds. Introduced in the mid-1950s, the T-28 replaced the venerable T-6 Texan as the U.S. Air Force's primary trainer, offering student pilots a more powerful, tricycle-gear aircraft that better prepared them for jet transition training. The Trojan later saw extended service in counter-insurgency roles during the Vietnam War. Project: 218472