The US Air Force (USAF) will retire its final Boeing KC-10 Extender tanker, ending a service run spanning more than four decades.
Air Mobility Command (AMC), which oversees the service’s fleet of tanker and cargo aircraft, says a retirement ceremony will be held for the last Extender refueller on 25 and 26 September at Travis AFB in California – the last base to operate the KC-10.
“Travis AFB will have the honour of bidding farewell to an aircraft that has been a vital component of the US military’s global reach and power projection capabilities for more than four decades,” the AMC says.
Following the retirement ceremony, the final KC-10 will depart Travis for long-term storage in the USAF’s famous desert “boneyard” at Davis-Monthan AFB, Arizona.
The milestone comes 43 years after the trijet KC-10 entered service with the USAF in 1981. A derivative of the Boeing DC-10 passenger jet, the KC-10 shares 88% commonality with its commercial ancestor, according to the air force, including the iconic tail-mounted GE Aerospace CF6-50C2 turbofan.
The swansong of the Extender does not come as a surprise. The USAF has been steadily reducing its fleet of KC-10s to make way for the newer Boeing KC-46 Pegasus refueller.
As of 2023, the air force had just 20 KC-10s left in the inventory, compared to more than 70 KC-46s and over 370 Boeing KC-135 Stratotankers.
The service began retiring Extenders in 2020, paring down the fleet to provide a source of spare parts for aircraft that remained on active service.
The AMC describes the transition to the 767-based tanker as a “new era of air-to-air refuelling for the mobility air forces”.
However, production and engineering challenges with the KC-46 programme delayed the 767-based jet’s entry into combat service until 2022, despite the first example being delivered to the USAF in 2019.
While several significant issues remain outstanding with the Pegasus, including a Pentagon-mandated redesign of the tanker’s remote boom control system, air force officials report being generally happy with the KC-46’s performance. That success has allowed the USAF to move forward with retiring the KC-10.
Despite the ongoing deactivations, the KC-10 continued to notch historic achievements in recent years. In 2023 the USAF used an Extender to test a novel aerial refuelling technique called “reverse flow”, in which a cargo aircraft transfers fuel to a tanker.
A demonstration of the concept saw a KC-10 pull fuel from a Lockheed Martin C-5M Super Galaxy strategic lifter, via the Extender’s transfer boom.
Previously, refuelling a tanker would have required the use of a second tanker aircraft. The reverse flow approach eliminates that constraint and makes more tanker aircraft available for other missions.
While the USAF is ramping up its reliance on the KC-46 to support current operations, the service’s long-term aerial refuelling plans are now in flux.
The service had for years planned for a three-stage modernisation of the tanker fleet, with three new aircraft labeled KC-X, KC-Y and KC-Z – with the Pegasus representing KC-X.
However, air force brass have subsequently scrapped the KC-Y “bridge tanker” and moved to accelerate fielding of the KC-Z, which has been rebranded the Next Generation Air-refuelling System or NGAS. That concept calls for a non-commercial derivative tanker capable of surviving and operating in contested airspace.
Little is known about the programme, for which the air force only this month released the first formal request for information from industry suppliers.
“We’ve gone through an evolution in our strategy to recapitalise the tanker fleet,” air force secretary Frank Kendall said on 16 September at the Air & Space Forces Association (AFA) conference near Washington, DC.
That evolution involved a two-year, formal analysis of alternatives of the NGAS capability requirements, which Kendall said will soon be completed. USAF assistant secretary Andrew Hunter, who oversees acquisition, says the analysis will help the service set capabilities for NGAS procurement.
Kendall in the coming months plans to release a sweeping new plan for the service’s portfolio of aircraft modernisation initiatives, including NGAS, a next-generation fighter and the development of uncrewed autonomous jets known as Collaborative Combat Aircraft.
