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 (FAC-A) support, by directing other aircraft in attacks on ground targets.On 22 December, a Requirements Action Directive was issued for the A-X CAS airplane, In 1969, the Secretary of the Air Force asked Pierre Sprey to write the detailed specifications for the proposed A-X project; Sprey's initial involvement was kept secret due to his earlier controversial involvement in the F-X project.
The A-10 was intended to improve on the performance of the A-1 Skyraider and its lesser firepower.
In 2005, a program was started to upgrade remaining A-10A aircraft to the A-10C configuration, with modern avionics for use with precision weaponry. With a variety of upgrades and wing replacements, the A-10's service life can be extended to 2040; the service has no planned retirement date as of June 2017.
By Vietnam, the 1940s-vintage propeller-driven Skyraider was the only dedicated close air support aircraft in the USAF's inventory.
While a capable aircraft for its era, with a relatively large payload and long loiter times, the propeller-driven design was also relatively slow and vulnerable to ground fire. On 7 June 1961, Secretary of Defense Mc Namara ordered the USAF to develop two tactical aircraft, one for the long-range strike and interdictor role, and the other focusing on the fighter-bomber mission. While the Phantom went on to be one of the most successful fighter designs of the 1960s, and proved to be a capable fighter-bomber, its lack of loiter time was a major problem, and to a lesser extent, its poor low-speed performance.
The former became the Tactical Fighter Experimental, or TFX, which emerged as the F-111, while the second was filled by a version of the U. It was also expensive to buy and operate, with a flyaway cost of million in FY1965, and operational costs over 0 per hour.