The 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 1973 Yom Kippur War and the US Operation Nickel Grass demonstrated the necessity of adequate air-refueling capabilities. Denied landing rights in Europe, USAF C-5 Galaxies were forced to carry a fraction of their maximum payload on direct flights from the continental United States to Israel. As a result C-5 crews were soon trained in aerial-refueling and the Department of Defense concluded that a more advanced tanker was needed.
In 1975, under the "Advance Tanker Cargo Aircraft" program, four aircraft were evaluated: the C-5 itself, the Boeing 747, the McDonnell Douglas DC-10, and the Lockheed L-1011. The U.S Air Force selected McDonnell Douglas's DC-10 over Boeing's 747 in December 1977.
The design for the KC-10 involved only modifications from the DC-10-30CF design. The major changes were the addition of a boom control station in the rear of the fuselage and extra fuel tanks below the main deck. The KC-10 has both a centerline refueling boom and a drogue/hose system on the right side of the rear fuselage. The KC-10 fleet was later modified to add wing-mounted pods for added refueling locations.
The KC-10 first flew on July 12, 1980. Early aircraft featured a paint scheme with light gray on the airplane's belly and white on the upper portion. A gray-green camouflage scheme was used on later tankers. Aircraft have since been switched to a medium gray color. The KC-10 boom operator is located in the rear of the airplane with wide window for monitoring refueling. The operator controls refueling operations through a digital, fly-by wire system.
The conversion was handled via the United States foreign military sales program, which in turn contracted McDonnell Douglas, the designer of both the DC-10 and the KC-10 tanker. Costs for the conversion were initially estimated at $89.5 million (FY 1994). The aircraft was to be equipped with both a boom and a probe and drogue system. However, because McDonnell Douglas did not have any experience with the requested Remote Aerial Refueling Operator (RARO) system, and because the third aircraft differed from the original two, the program could not be completed at budget. By omitting the probe and drogue system and a fixed partition wall between the cargo and passenger, the cost could be limited at $96 million. To make up for the cost increase McDonnell Douglas hired Dutch companies to do part of the work. The actual converting of the aircraft for instance was done by KLM. Conversion of the aircraft was done from October 1994 to September 1995 for the first aircraft and from February to December 1995 for the second. This was much longer than planned, mostly because McDonnell Douglas did not deliver the parts in time. This would have again increased the cost, but in the contract for the AH-64 Apaches which the Royal Netherlands Air Force also bought from McDonnell Douglas, the price was agreed to be kept at $96 million.
The KC-10 was delivered to the USAF Strategic Air Command (SAC) (then in control of AAR assets) from 1981 to 1987. SAC had KC-10 Extenders in service from 1981-92, when they were re-assigned to the newly established Air Mobility Command.
In the AAR role, the KC-10s have 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-theatre tactical role.
When faced with refusals of basing and overflight rights from continental European countries during Operation El Dorado Canyon, the U.S. was forced to use the UK-based F-111s in the 1986 air-strikes against Libya. The KC-10s allowed 29 F-111s to reach their targets.
There are 59 KC-10 Extenders currently in service. The KC-10 has a significantly larger fuel capacity than the Air Force's other tanker plane, the KC-135, which has over 500 in service. The USAF's KC-10s are stationed primarily at Travis AFB, California and McGuire AFB, New Jersey.
The KC-10 is currently the world's longest-ranged production aircraft (because the payload tanks are interconnected with the fuel source), surpassing even the Boeing 777-200LR, the longest-range commercial aircraft.
A significant feature of the KC-10 is that in addition to the USAF refueling boom, it also has a separate hose and drogue system used by the U.S. Navy, Marine Corps, and most NATO allied aircraft. This gives the KC-10 the ability to refuel USAF, USN, USMC and other NATO aircraft, all in the same mission.
The two Dutch KDC-10s, T-264 "Prins Bernard" and T-235 "Jan Scheffer", are used for both refueling and transport. They are stationed on Eindhoven Airport as part of the 334th Transport Squadron. Of the 5500 hours flown in the first 3 years of use, the aircraft were used in their tanker role for 50% of the time. Besides being used for the air force and allies, the KDC-10s are also used to support peacekeeping and humanitarian aid operations. Of the first 3 years, 32% of the flight hours were used for peacekeeping and humanitarian aid.
In this function, the aircraft have been deployed to Kosovo to evacuate refugees, to the Caribbean and Central America to provide humanitarian aid after the hurricanes Luis, Georges and Mitch and to various countries in Africa and Asia to provide development aid. In 1998, the aircraft were also used to evacuate Dutch citizens from Indonesia during the Fall of Suharto.
Also, commercial refueling companies Omega Air and Global Air Tanker Service operates two KDC-10 tankers for lease (N852V and N974VV). Unlike the Dutch KDC-10s however, they were converted from DC-10-40s and do provide probe and drogue refueling capabilities.
On September 17, 1987 aircraft tail number 82-0190 was lost after an explosion and subsequent fire. The tanker was undergoing maintenance on the ground at Barksdale AFB, LA. One member of the ground crew died in the fire.