Its 508th Mature Aircraft and Simulator Sustainment Group, and later, the 558th Aircraft Sustainment Group was responsible for acquiring improved capabilities and sustainment for 36 different aircraft weapon systems. "Mature aircraft" are out of production but still active in the Air Force inventory. The largest programs were associated with the Fairchild A-10 Thunderbolt II, Cessna T-37 Tweet and Northrop T-38 Talon. The groups also supported aircraft not in the active Air Force inventory that were flown by foreign countries or other agencies of the United States. This group included the McDonnell F-4 Phantom II, Northrop F-5 Freedom Fighter, Douglas C-47 Skytrain and others.