Gates C-21 Learjet USAF airplane model. Delivery of the C-21A fleet began in April 1984 and was completed in October 1985. The C-21 (Gates Learjet 35) fleet is dispersed throughout the Air Force and consists of 73 active duty and 4 Air National Guard aircraft stationed at 14 worldwide locations. On 01 April 1997, all continental U.S.-based C-21s were realigned under Air Mobility Command, with the 375th Airlift Wing at Scott Air Force Base, Ill., as the lead command. C-21s stationed outside the continental United States are assigned to the theater commanders.
The C-21 aircraft provides operational support airlift for Air Force Commanders, the Superintendent of the Air Force Academy, key federal officials, members of Congress and senior-ranking military leaders. The aircraft also provide a 24hour alert for time sensitive medical evacuation missions which could be required to go anywhere in the United States. In wartime, the C21A provides worldwide time-sensitive movement of people and cargo.