Take a look inside an Air Force aerial tanker that kept fighter jets and bombers in the air

KC-10s entered service in the Air Force in 1981. They provided in-flight refueling in combat operations during the Gulf War and the Iraq War, and supported aircraft during Operation Allied Force in 1999.

They also helped carry out the largest non-combatant evacuation operation in US history during the Taliban offensive in Afghanistan in 2021, when 40% of the KC-10 fleet was deployed to evacuate over 3,000 people and refuel other aircraft, according to the Air Force.

The KC-10 was a military version of the DC-10 airliner built by McDonnell Douglas, which merged with Boeing in the late 1990s. The DC-10 has similarly been retired by commercial airlines.

While KC-10 refueling jets have been retired, the Air Force still uses KC-135 Stratotankers, which entered service in 1957, and introduced the KC-46A Pegasus in 2019 as part of efforts to upgrade its aging tankers.

The US Air Force plans to buy over 260 KC-46s from Boeing, with each costing about $200 million. The Stratotankers and Pegasus aircraft have fallen short of readiness standards in recent years.

With a capacity of over 356,000 pounds of fuel, KC-10s could carry nearly twice as much fuel as the KC-135 Stratotanker. However, KC-10s were phased out, while the Air Force still uses KC-135s.

So, why didn’t KC-10s remain in service as long?

“You can ask 10 different people and get 20 different answers to that,” Michael Hurlburt, operations manager at the Air Mobility Command Museum and an Air Force veteran, told Business Insider.

Hurlburt thinks the KC-10’s third engine was partially to blame, since its position above the fuselage on the vertical stabilizer required special scaffolding platforms for inspection before every flight, which he called a “maintenance nightmare.”

The museum’s KC-10A Extender was built as a prototype for a larger, longer-range alternative to KC-135 Stratotankers. It clocked over 32,560 flying hours before it was retired to the Air Mobility Command Museum in 2022.

The KC-10A Extender measures 181 feet and 7 inches long with a wingspan of 165 feet and 4 ½ inches.

The aircraft is open for guided tours. Museum admission is free.

The flight deck and passenger compartment are located up front. The cargo bay takes up most of the remaining space, with the refueling operator station at the back of the plane.

Seats in the passenger compartment resembled those on regular commercial airlines.

For cargo transport missions, a loadmaster would join the crew. For aeromedical evacuations, two flight nurses and three medical technicians were added.

On refueling missions, extra fuel tanks were also kept in the cargo bay, totaling up to 356,000 pounds of transferable fuel.

WARPs can be mounted under a tanker’s wings to provide additional refueling points. On the KC-46, the successor to the KC-10, WARPs are in testing to enable the Pegasus to simultaneously refuel two aircraft.

To receive fuel in-flight, other aircraft positioned themselves behind and lower than the KC-10.

In KC-10s, boom operators sat upright. In KC-135s, boom operators lie on their stomachs to operate the controls.

The boom operator’s job is to guide a rigid pipe into a receptacle on the receiving aircraft.

Once the boom is connected, the operator turns on the pumps to begin transferring fuel at a maximum rate of 1,100 gallons per minute. An F-15 Eagle, for example, can carry over 5,000 gallons of jet fuel.

In-flight refueling is a dangerous operation requiring tankers and the planes they refuel to fly within 8 to 12 feet of each other at hundreds of miles per hour.

“You’re close enough that you can wave and say hi to the other pilot in the other airplane,” Hurlburt said.

Mistakes can be catastrophic. In July 2025, a KC-46A Pegasus refueling aircraft’s boom got stuck in the receptacle of an F-22A Raptor and broke off, causing nearly $10 million in damage. In March, a KC-135 tanker crashed in Iraq, killing all six crew members.

The boom is labeled with signage from the 305th Air Mobility Wing, located at Joint Base McGuire-Dix-Lakehurst in New Jersey, where this KC-10A Extender served from 1995 until its retirement in 2022.

“Very few airplanes have something like this, and very few people get to see areas like this,” he said. “We’re pretty proud of being able to show this off.”