Fairchild Republic A-10A Thunderbolt II The A-10 is the first U.S. Air Force aircraft designed specifically for close air support of ground forces. It is named for the famous P-47 Thunderbolt, a fighter often used in a close air support role during the latter part of World War II. The first in-flight testing of the GAU-8 was done on Feb. 26, 1974. The gun was fired for the first time in flight with combat ammunition on June 19, 1974. The Avenger fired more than 39,000 rounds of ammunition during