While the A-10 Close Air Support Aircraft (CAS) had been planned for by the U.S. Air Force (USAF) as early as the mid to late 1960s, its true origin can be traced to December 1970 when Secretary of the Air Force Robert C. Seamans, Jr., awarded contracts for two prototypes, both designated the A-X. It would eventually be called the Thunderbolt II, descendent of Republic's famous World War II P-47 Thunderbolt I. But Air Force pilots would also call the Thunderbolt II the 'Warthog,' 'Hog,' or 'HAWG' because it looked ugly, and because of its tenacious close-in and low-level fighting capabilities, especially during inclement weather. The 'Hog,'built for use against Soviet tanks in Europe during the Cold War, was not welcomed by most Air Force pilots, who felt that it flew much too slowly and clumsily. Indeed, the 1970s marked an era of fighter pilot resurgence after a long period in which strategic airpower and the bomber pilots had overshadowed them. Airmen who had any hope of advancement in the 1970s, however, wanted to fly the F-15 and F-16, both high- speed, highly maneuverable fighter jets. So when the 'Hog,'after much testing and flying competition, finally entered the Air Force inventory, it had to fight for acceptance for nearly 2 decades. Not until it won admiration for its spectacular performance in the first Persian Gulf War was it fully accepted. Like the 'Ugly Duckling' of nursery fame, the A-10 endured, finally rising to prominence and outlasting most of the aircraft flown by the USAF. At this writing, the A-10s projected lifespan has been extended to 2030, putting it in the category of the USAF's two other great workhorses, the B-52 bomber and the C-130 transport (Figure 1).