The Fairchild Republic A-10 Thunderbolt II is a single-seat, twin-turbofan, straight-wing, subsonic attack aircraft developed by Fairchild Republic for the United States Air Force (USAF). In service since 1977, it is named after the Republic P-47 Thunderbolt, but is commonly referred to as the "Warthog" or simply "Hog".[3] The A-10 was designed to provide close air support (CAS) to ground troops by attacking enemy armored vehicles, tanks, and other ground forces; it is the only production-built aircraft designed solely for CAS to have served with the U.S. Air Force.[4] Its secondary mission is to direct other aircraft in attacks on ground targets, a role called forward air controller (FAC)-airborne; aircraft used primarily in this role are designated OA-10.