The KC-10A Extender is an air mobility command advanced tanker and cargo aircraft designed to provide increased global mobility for US armed forces. Its primary mission is aerial refueling but it is capable of simultaneously carrying fighter support personnel and equipment on overseas deployments. It can also transport litter and ambulatory patients using patient support pallets during aeromedical evacuations. The KC-10A was the second consecutive McDonnell Douglas transport aircraft to be selected by the US Air Force following the C-9 Nightingale.
The KC-10A was derived from the civilian DC-10 airliner and entered service in 1981. Although it retains 88 percent of the DC-10, it has additional systems and equipment necessary for its Air Force mission. These include military avionics, seated aerial refueling operator station, and aerial refueling receptacle and satellite communications. It also has three more large fuel tanks. Using either an advanced aerial refueling boom, or a hose and drogue centerline refueling system, the KC-10A can refuel a wide variety of US and allied military aircraft within the same mission. The aircraft is equipped with lighting for night operations.
During Operations Desert Shield and Desert Storm in 1991, the KC-10A provided in-flight refueling to aircraft from the US armed forces and other coalition forces. In-flight refueling was vital to rapid airlift of materiel and forces in the early stages of Desert Shield. Furthermore, the KC-10A, along with the KC-135, transported tons of cargo and thousands of troops in support of the Persian Gulf buildup. The KC-10A and the KC-135 conducted approximately 51,700 separate refueling operations and delivered 475 million liters of fuel without missing a single schedule.