Harrisburg Air National Guard Base is a United States Air Force base, located at Harrisburg International Airport, Pennsylvania. It is located west-southwest of Middletown, Pennsylvania. The Pennsylvania Air National Guard facility is sited on the location of the former Olmsted Air Force Base, which was closed in 1969. The 193d Special Operations Wing operates EC-130J Hercules aircraft, designated as "Commando Solo" for special operations missions. Today the airfield is split between civilian activities, Harrisburg IAP (MDT) and military activities, which now carry the Harrisburg ANGB title. After Olmsted AFB closed in 1970 major civilian air activities moved from Capital City Airport, near Harrisburg over to the former Olmsted site. Middletown Air Depot The installation saw its first military use by the United States Army Signal Corps in 1898. The first known use of the field by military aircraft was when Middletown Airfield opened in 1917 as a supply depot and maintenance center for Signal Corps aircraft. The first airplanes landed in 1918 at Middletown Air Depot, when it was under the administration of the Signal Corps of the United States Army. In 1939, it was still known by this name. Middletown had an abundance of engine and airframe shops and a supply distribution system that made it a significant facility, but a poor runway that, it was felt, would be too expensive to improve. It would involve claiming marsh land and portions of the Susquehanna River (both of which have since been accomplished) and the Air Force leadership at that time determined that more land for supply and maintenance buildings was needed. After World War I and the reconstitution of the United States Army Air Service in 1922, the facility became a logistics and maintenance support of Air Service aircraft and equipment through its host unit, the Middletown Air Depot (later Middletown Air Materiel Area under the U.S. Army Air Corps). During World War II, numerous U.S. Army Air Forces transport and reconnaissance units were organized and formed at Olmsted Army Airfield. Once equipped, they were reassigned to training bases. The Middletown Air Depot-cum-Middletown Air Material Area was a major support installation to the U.S. Air Force and its predecessor organizations for decades. Renaming for Robert Olmsted The installation was renamed in honor of 1st Lieutenant Robert Sanford Olmsted, U.S. Army Air Service, on 11 March 1948. First Lieutenant Olmsted was killed in a ballooning accident over the village of