The KC-10 Extender aerial refueling jet has logged its last combat mission, closing a penultimate chapter in the airframe’s four decades of service as it heads into retirement.

The last deployed KC-10 left Prince Sultan Air Base, a U.S.-run outpost in Saudi Arabia, on Oct. 5 after supporting combat operations in U.S. Central Command, the Air Force said in a release Friday. The service did not provide details on the tanker’s final sorties.

“The KC-10 has been the anchor of air refueling in the [region] since Desert Storm,” 908th Expeditionary Air Refueling Squadron boss Maj. Joseph Rush said in the release. “Thousands of airmen have deployed to support KC-10 combat operations. … To be here at the culmination of that legacy is a privilege.”

The 908th EARS has flown the KC-10 in the U.S.-led military campaigns against terror groups in Afghanistan, Iraq and Syria from Prince Sultan Air Base and Al Dhafra Air Base in the United Arab Emirates since 2002.

The War Zone confirmed Thursday that the mission was the KC-10′s last ride in combat operations worldwide. The Air Force did not respond to a request for comment by press time.

Since entering service in 1981, the KC-10 has moved thousands of tons of cargo, transported thousands of troops and supplied many millions of gallons of fuel to other aircraft in conflicts around the world. The jets act as airborne gas stations where military aircraft can refuel without needing to divert to brick-and-mortar bases for service.

“For a fighter, aerial refueling can take a two-hour unrefueled flight time and turn it into an eight-hour combat mission,” Rush said in the release. “That translates to uninterrupted close air support coverage for coalition troops on the ground or defensive counter-air coverage to high-value airborne assets in a combat zone.”

The KC-10′s exit is part of the Air Force’s sweeping plan to overhaul its aging inventory with new aircraft that are cheaper to maintain and can withstand the demands of future wars.

The service is sunsetting the 59-jet Extender fleet to make way for Boeing’s new KC-46 Pegasus tanker, which can carry more than 212,000 pounds of fuel, 65,000 pounds of cargo and nearly 60 passengers. The new fleet is also equipped with more defensive measures that can help it survive enemy attacks, and is a testbed for communication software that could make it a data-sharing hub for forces in the area.

KC-10s will continue to fly stateside as units finish swapping out older airframes and training on the KC-46, the release said.

The first KC-10 headed to the aircraft graveyard at Davis-Monthan Air Force Base, Arizona, in July 2020. The last of the fleet is slated for retirement in September 2024.

Despite its age, airmen often hail the KC-10 as their favorite airframe in a tanker enterprise hampered by multiple software and hardware design problems.

The KC-135 Stratotanker has faced years of flight restrictions as the service tries to fix malfunctioning autopilot software. And the KC-46 is in the midst of years of upgrades to its external cameras, the refueling boom, fuel leaks, cargo restraints and more that have delayed its full participation in global operations.

The final deployment is a “bittersweet” end to KC-10 operations, Rush said in the release.

“It’s exciting for our community, as we get to take a lot of the best parts of the KC-10 culture we’ve built over the last 42 years and bring those best practices and experiences to a brand new weapons system,” he said.