It is commonly referred to by the nicknames "Warthog" or "Hog", although the A-10's official name comes from the Republic P-47 Thunderbolt, a World War II fighter-bomber effective at attacking ground targets. The A-10 was designed for close air support (CAS) of friendly ground troops, attacking armored vehicles and tanks, and providing quick-action support against enemy ground forces. It entered service in 1976 and is the only production-built aircraft that has served in the USAF that was designed solely for CAS. Its secondary mission is to provide forward air controller–airborne support, by directing other aircraft in attacks on ground targets. Aircraft used primarily in this role are designated OA-10. The A-10 has a cantilever low-wing monoplane wing with a wide chord. The aircraft has superior maneuverability at low speeds and altitude because of its large wing area, high wing aspect ratio, and large ailerons. The wing also allows short takeoffs and landings, permitting operations from primitive forward airfields near front lines. The aircraft can loiter for extended periods and operate under 1,000-foot (300 m) ceilings with 1.5-mile (2.4 km) visibility. It typically flies at a relatively low speed of 300 knots (350 mph; 560 km/h), which makes it a better platform for the ground-attack role than fast fighter-bombers, which often have difficulty targeting small, slow-moving targets. For extensive details on the development, operational history and different moels, click here. Specifications below are for the A-10A single-seat close air support, ground-attack production version.