Davis–Monthan Air Force Base (DM AFB) is a United States Air Force base southeast of downtown Tucson, Arizona. It was established in 1925 as Davis–Monthan Landing Field. The host unit for Davis–Monthan AFB is the 355th Wing (355 WG) assigned to Twelfth Air Force (12AF), part of Air Combat Command (ACC). The base is best known as the location of the Air Force Materiel Command's 309th Aerospace Maintenance and Regeneration Group (309 AMARG), the aircraft boneyard for all excess military and U.S. government aircraft and aerospace vehicles. Davis–Monthan Air Force Base is a key ACC installation. The 355th Wing (355 WG) provides A-10 Thunderbolt II close air support and OA-10 forward air controllers to ground forces worldwide. The 355 FW is a host unit, providing medical, logistical, mission and operational support to assigned units. The 355 FW is the sole formal training unit for the A-10 aircraft, providing initial and recurrent training to all U.S. Air Force A-10 and OA-10 pilots, to include those in the Air Force Reserve Command (AFRC) and the Air National Guard (ANG). The 355th is ACC's executive agent for INF and START treaty compliance. In October 2018, the 563rd Rescue Group, previously a geographically separated unit of the 23rd Wing at Moody AFB, Georgia, was transferred to the 355th Wing, along with its HC-130J COMBAT KING II and HH-60G Pave Hawk aircraft. One of the wing's tenant units, the 55th Electronic Combat Group (55 ECG), is a geographically separated unit (GSU) of the 55th Wing (55 WG) at Offutt AFB, Nebraska. Tasked to provide offensive counter-information and electronic attack capabilities in support of U.S. and Coalition tactical air, surface, and special operations forces, the 55 ECG unit employs its Lockheed EC-130H Compass Call aircraft worldwide in tactical air operations in war and other contingencies. It also provides initial and recurrent training to all EC-130H Compass Call pilots, navigators, electronic warfare officers, and aircrew. Another major tenant unit is the Air Force Reserve Command's (AFRC) 943rd Rescue Group (structured as a GSU under AFRC's 920th Rescue Wing at Patrick Space Force Base, Florida). Equipped with HH-60G Pave Hawk helicopters and Guardian Angel personnel, the 943 RQG is tasked to provide combat search and rescue (CSAR) and personnel recovery (PR) support worldwide. Perhaps the most prominent tenant is the 309th Aerospace Maintenance and Regeneration Group (309 AMARG) of the Air Force Materiel Command (AFMC). As the main