The McDonnell Douglas KC-10 Extender is an air-to-air tanker aircraft in service with the United States Air Force derived from the civilian DC-10-30 airliner. The KC-10 was the second consecutive McDonnell Douglas transport aircraft to be selected by the US Air Force following the C-9 Nightingale. The similar KDC-10 is in service with the Royal Netherlands Air Force.
The KC-10 was delivered to the USAF Strategic Air Command (SAC), then in control of air refueling assets from 1981 to 1987. SAC had KC-10 Extenders in service from 1981 until 1992, when they were re-assigned to the newly established Air Mobility Command. In the air-to-air refueling (AAR) role, the KC-10s have been operated largely in the strategic refueling of large number of tactical aircraft on ferry flights and the refueling of other strategic transport aircraft. Conversely, the KC-135 fleet has operated largely in the in-theater tactical role.
There are 59 KC-10 Extenders in service with the United States Air Force (USAF) as of 2010. The KC-10 has a significantly larger fuel capacity than the Air Force's other main tanker, the KC-135. with over 440 in service in 2009. The USAF's KC-10s are stationed primarily at Travis AFB, California and McGuire AFB, New Jersey.