They say there’s “no kicking *ss without tanker gas.” NKAWTG. With so much churn associated with the development of the Boeing KC-46A Pegasus next generation aerial refueling tanker, we sometimes forget about the most recent adaptation of a commercial aircraft for the military tanker role. The McDonnell Douglas KC-10A Extender is built on the DC-10-30CF convertible passenger and cargo variant of the DC-10. It combines the ability to haul copious amounts of cargo and personnel with high fuel transfer capacity via both boom and probe/drogue. In other words, the KC10A is one flexible young gas passer.
The US Air Force took a close look at aerial tanker requirements toward the end of the war in Vietnam and found a need for additional tankers built on wide body platforms allowing higher capacities. In 1975 the Advanced Tanker Cargo Aircraft Program pitted tanker variants of the Lockheed C-5A Galaxy strategic airlifter, the Boeing 747 airliner, and the Lockheed L-1011 Tristar airliner against the McDonnell Douglas DC-10. The final competition came down to the 747 and the DC-10, with the DC-10 derivative being chosen in 1977 thanks in part to its ability to operate from shorter runways.
The KC-10A was first flown in 1980, but development of the KC-10 actually began as soon as the DC-10 airliner version entered service in 1971. Two DC-10s were flown to Edwards Air Force Base in California to simulate potential wake turbulence issues that might be experienced during aerial refueling behind a DC-10-derived tanker in 1972. In 1973 the US Air Force conducted Operation Nickel Grass to supply Israel with weapons and supplies during the Yom Kippur War. The operation reinforced the importance of aerial refueling and flexibility of transport aircraft when political considerations prevented landing rights in Europe.
The modifications required to turn a DC-10-30CF into a KC-10A included removal of airliner-specific equipment, most windows, and lower cargo hold doors. Additions included improved cargo-handling systems such as powered rollers and winches, military avionics, seven fuel cells for transferable fuel located in the cargo holds, tail-mounted Advanced Aerial Refueling System Boom (ARRB), probe/drogue refueling equipment, lighting for night operations, and a boom operator station in the aft fuselage. The last 20 KC-10As built were delivered with additional probe/drogue refueling “pods” mounted near each wingtip.
The KC-10A’s fuel capacity is 356,000 pounds, which is nearly double that of the Boeing KC-135 Stratotanker. The inclusion of both the boom and probe/drogue refueling systems allows the KC-10A to refuel nearly all US and NATO military aircraft. The KC-10A boom operator controls the ARRB via a digital fly-by-wire system. The versatility of the KC-10A allows it to carry up to 75 people with 146,000 pounds of cargo in a combi configuration or 170,000 pounds of cargo on up to 27 pallets in pure freight configuration. Thrust is supplied by three General Electric CF6-50C2 high-bypass turbofan engines combining to produce more than 150,000 pounds of thrust. The KC-10A’s unrefueled range in 4,400 miles when loaded up, and it is equipped with an inflight refueling receptacle in order to receive fuel.
During refueling testing in October of 1980, the first aircraft to be plugged and passed gas by the KC-10A Extender was a Lockheed C-5A Galaxy– at one point a potential rival. Strategic Air Command (SAC) took delivery of the first KC-10As at Barksdale Air Force Base (AFB) in March of 1981. The last of the 60 KC-10As built was delivered to SAC in November of 1988. When SAC was disbanded in 1992, the US Air Force’s Air Mobility Command (AMC) became the new owners of the Air Force’s youngest tanker fleet. Several SAC KC-10As were utilized to refuel the F-111 Aardvarks and other aircraft forced to fly around the European land mass from the UK to Libya and back during Operation El Dorado Canyon in 1986.
During Operations Desert Shield and Desert Storm KC-10As took advantage of their flexible load carrying capability to move thousands of tons of cargo and thousands of personnel while refueling aircraft en route to the sandbox. Without missing a single scheduled transfer, KC-10As and KC-135s performed more than 51,000 plugs delivering more than 125 million gallons of fuel. KC-10As have also passed gas during Operation Allied Force, kept interceptors and surveillance aircraft fueled up during these tense post-9/11 days of Operation Noble Eagle, and flown thousands of sorties in support of US and NATO armed service general refueling requirements.
Talk of retirement for the 59 KC-10As in service seems premature. The aircraft are (or were) expected to serve through 2043. The ability to refuel as many as three aircraft simultaneously and the higher transferable fuel capacity of the KC-10A seem to make it a solid platform, but politics will surely muddle up the process. The aircraft’s versatility and relative youth are also points in its favor. Boeing began a modernization program in 2010, updating navigation, communications, air traffic management, and surveillance equipment. A 2011 contract for avionics and cockpit updates was awarded to Rockwell Collins.
Today the KC-10A Extender is operated by the 305th Air Mobility Wing (AMW) based out of Joint Base McGuire-Dix-Lakehurst near Trenton in New Jersey and the 60th AMW based out of Travis AFB not far from San Francisco in in California. The Air Force Reserve (AFRES) 349th AMW (at Travis AFB) and the 514th AMW (at McGuire) also operate KC-10As. Gone are the days when KC-10As were painted in those gorgeous white/gray/blue SAC colors. We endured the green over gray years and now we’re stuck with overall gray. Progress?
The Royal Netherlands Air Force (Koninklijke Luchtmacht or KLu) operate two KDC-10s. They are former Martinair DC-10-30CF aircraft that were converted to tankers by KLM Airlines. One of the aircraft slated for conversion crashed in 1992, forcing the KLu to purchase a third DC-10 from Martinair. These aircraft do not have the drogue refueling equipment installed. They entered service with the KLu 334th Squadron in 1995 as the only other military operators of DC-10-based aerial refueling tankers.
Omega Aerial Refueling Services and Global Air Tanker Service each operated a single KDC-10 tanker. These lease aircraft are equipped with the wingtip drogue pods and have often supported large surge activities and fighter drags. These are former DC-10-40 aircraft. Omega’s N974VVis still active but Global’s N825V has been stored at Marana for many years. DC-10s are also being utilized as aerial firebomber tankers by several companies today. So hats off to the KC-10A- the undisputed heavy-lifting gas passer.