The McDonnell Douglas KC-10 Extender is an American tanker and cargo aircraft that was operated by the United States Air Force (USAF) from 1981 to 2024. A military version of the three-engine DC-10 airliner, the KC-10 was developed from the Advanced Tanker Cargo Aircraft Program. It incorporates military-specific equipment for its primary roles of aerial refueling and transport. It was developed to supplement the KC-135 Stratotanker following experiences in Southeast Asia and the Middle East. The KC-10 was the second McDonnell Douglas transport aircraft to be selected by the Air Force following the C-9. A total of 60 KC-10s were produced for the USAF. The Royal Netherlands Air Force operated two similar tankers from 1995 to 2021 designated KDC-10 that were converted from used civilian DC-10, instead of purpose built aircraft.