Air Crews Remember the Reliable KC-10 with Affection

After decades of service, a legendary tanker says farewell.

I’m seated in the tail of a U.S. Air Force KC-10 that is climbing to 25,000 feet somewhere over Big Sur. Looking out from the boom operator’s large rear-facing window, I soon spot four F-15C fighter jets emerging from the clouds of the California sky below. They were our first receivers for the day.

The McDonnell Douglas KC-10 Extender—unmistakable with its three massive, howling engines—has been the military’s airborne refueling station for more than 40 years. I was aboard one of the last active KC-10s in the inventory, tail number 1948, nicknamed Excalibur.

The aircraft commander, Lieutenant Colonel Andy Baer, coordinated the aerial refueling rendezvous with the fighters. Staff Sergeant Tracy Koshman, the flight engineer, managed the KC-10’s systems in the cockpit, while boom operator Staff Sergeant Cameron Carl sat next to me in the rear of the aircraft.

As Carl extended the KC-10’s mechanical boom, he guided the first F-15C in, calling out distances until he made contact with the aircraft’s fuel receptacle. “Contact,” Carl radioed to the fighter pilot. In just two minutes, four thousand pounds of kerosene-based jet fuel surged into the F-15C’s tanks—a small top-off compared to the 100,000 pounds consumed by cargoplanes and bombers.

“Aerial refueling tankers don’t often get a lot of attention, but they are some of the most important aircraft in the U.S. military inventory,” says Mike Hankins, the National Air and Space Museum’s curator for post-World War II aviation. “Tankers allow U.S. aircraft to reach all around the globe, and tankers are what enable so many U.S. military aviators to accomplish their missions. The KC-10 was a major increase in tanker capabilities at a key moment in the Cold War. Using an airframe that was more modern for its time, the KC-10 was a huge increase, not just in the amount of fuel it could carry, but also the types of aircraft it could refuel and the amount of space it had for cargo or medical evacuations. The KC-10, in many ways, helped enable the U.S. military to maintain the type of global presence and influence it wanted to have as the Cold War grew increasingly intense.”

The distinctive tri-jet, widebody profile of the KC-10 makes it familiar to aficionados of civil aviation: It’s a military variation of the McDonnell Douglas DC-10, and it retains 88 percent of systems commonality with the storied passenger jet. Gone are the rows of seats that would have held close to 400 passengers. In their place are military systems that include the boom pod, a seated aerial refueling operator station where the receiver aircraft can be seen through a wide window. During boom refueling operations—which use a digital, fly-by-wire system—fuel is transferred to the receiver at a maximum rate of 1,100 gallons per minute.

Like most aeronautical innovations, the KC-10 was born of need. Operation Rolling Thunder (a three-year bombing campaign conducted by U.S. forces during the Vietnam War) had revealed significant deficiencies in the United States’ air refueling capabilities. Vietnam would become known as the first “tanker war,” owing to the military’s growing dependence on refueling from the Boeing KC-135 Stratotanker, which could extend the missions of such critical aircraft as Boeing B-52s, McDonnell Douglas F-4s, and Republic F-105s. From 1964 through 1973, KC-135 tanker crews transferred nearly 1.4 billion gallons of fuel to receiving aircraft.

Still, KC-135s, which had been in operation since the late 1950s, had limitations in terms of range and fuel capacity, and they required relatively long runways for takeoffs and landings. Operation Nickel Grass—the emergency U.S. military airlift to Israel during the 1973 Arab-Israeli War—further accentuated these shortcomings, notably the need for reliable in-flight fueling capabilities to sustain distant overseas operations. Nickel Grass had also strained the cargo delivery capacity of the Air Force’s C-5 Galaxy transports. 

In response, the U.S. Advanced Tanker Cargo Aircraft Program was launched in 1975 to find an aircraft that could bridge the gap between huge cargo haulers like the C-5 and dedicated refuelers like the KC-135. Four aircraft types were evaluated. The DC-10 emerged as the favorite, due to its ability to operate from shorter runways.

On July 12, 1980, the KC-10 cargo tanker made its first flight. Revolutionary in design, the KC-10 could use both an aerial boom system for receptacle-equipped aircraft and a hose-and-drogue system for probe-equipped aircraft—during the same flight. While Air Force jets lined up for boom refueling, U.S. Navy, U.S. Marine Corps, and NATO aircraft utilized the hose reel, showcasing the KC-10’s unmatched versatility.

Able to do double-duty as a cargo transport, the KC-10 can carry an astounding 170,000 pounds of cargo, nearly matching the capacity of a Boeing C-17. It can also carry 356,000 pounds of fuel. With a maximum speed of 619 mph, the KC-10 became a vital asset in every U.S. military conflict since its debut during Operation Urgent Fury in Grenada in 1983. 

Former KC-10 boom operator Rob Tabor will always admire the aircraft: “The ‘10’ was a marvel—dual-role capability. We could go into a fighter base, scoop up their cargo, support personnel, and planes—take off and get it all done.”

Operation El Dorado Canyon in 1986 solidified the KC-10’s legendary status during a time of global tension. The mission aimed to strike Libyan targets in retaliation for state-sponsored terrorism, including a bombing in West Berlin that killed an American soldier. 

With France, Spain, and Italy denying U.S. overflight rights for fear of retaliation, mission planners had to devise a new route to Libya from England, necessitating significant fuel support for the 6,500-mile roundtrip mission.  

On April 14, 1986, 24 U.S. Air Force F-111F strategic bombers launched from Royal Air Force Mildenhall in England, supported by eight KC-10s, known as the “Mother Tankers,” which would refuel the F-111s eight times over the course of the mission. 

“They chose my commander and me to lead the formation,” says former KC-10 pilot Lieutenant Colonel Mike Ethridge. “Everything we were going to do that night was based on timing to hit this window at the right moment to release our guys.”

Per the military’s attack plan, six General Dynamics F-111s and half the tankers returned to base once the mission was underway, leaving the remaining fighter-bombers to continue the long journey to Libya, assisted by the other KC-10s. 

“Millions of pounds of fuel were launched that night,” says Baer. “Just staggering. Those crews became legends that day.”

The KC-10 was also capable of carrying specialized fuel for Lockheed’s SR-71, which flew Mach 3 reconnaissance missions at an altitude of 80,000 feet. 

“I was selected to fly the SR-71 operation missions,” says Ethridge. “The SR-71 sucked a lot of gas when it got down into normal air. If the SR-71 didn’t refuel quickly upon descent, it risked aborting the mission.”

While flying a KC-10, Ethridge rendezvoused with an SR-71 at an air refueling control point, using a prearranged frequency to communicate. “We were flying straight towards them at [370 mph] and they were doing Mach 3,” says Ethridge.

 The KC-10 served as an airborne tactical air navigation system station, enabling both aircraft to know each other’s positions accurately before the SR-71 slowed down to 400 mph and lined up behind the tanker for the refueling. “The KC-10 would accelerate while the SR-71 took on about 100,000 pounds of fuel,” says Ethridge.

Dancing with a Giant

After refueling all four of the F-15Cs over Big Sur, we rendezvoused with a C-5M Super Galaxy, the Air Force’s largest airplane. The C-5’s massive nose hovered near our window, carefully taking on fuel. 

“I call it the ‘negotiation’ when the C-5 gets about 30 feet behind us,” Baer explains, noting how the C-5’s bow wave—a shock wave that forms in front of an aircraft—could lift the KC-10’s tail. “It’s a dance of precision,” says Baer, emphasizing the critical communication between boom operators and receiver pilots.

Refueling the C-5 with the KC-10 was additionally challenging due to turbulence from the tanker’s tail engine. “You’d come up just shy of grabbing the boom, then bam! ” says former C-5 pilot Gerry Ward. “A ton of jet wash would hit you like a brick wall. It was a vibrating mess, and we had to crank up the power to make contact.”

After a five-hour flight on Excalibur, I sat down with former KC-10 pilot Colonel Jay Johnson, commander of the 60th Air Mobility Wing at Travis Air Force Base in California. “The tanker is what makes fighters offensive weapons,” he says, describing the KC-10 as a lifeline for pilots in hostile territory who are running low on fuel.

Johnson recounted a harrowing experience from a 2004 mission over Iraq: “We were shot at while refueling F-16s. It was my first and only time getting shot at. We could cruise at Mach .82, but that night we maxed it out near .88 to get the heck out of there.” 

The legacy of the KC-10 is now being carried forward by the Boeing KC-46 Pegasus, which offers the efficiency of a two-engine design and greater automation.  The new aircraft has replaced the KC-10’s large rear boom window and boom operator’s pod with advanced camera systems and virtual reality technology. “The Pegasus is a technological marvel,” says Johnson. “The KC-10—that was a warrior.”

We’re the last in a long line of truly meritorious service, surrounded by wonderful people who have cared for and operated this jet with resolve and tremendous appreciation.”
—Lieutenant Colonel Andy Baer

The KC-46 signifies a major shift from analog to digital systems. Says Baer: “The KC-10 has rudimentary computers from 1979. The engineer is like a human computer, managing systems like fuel and hydraulics—the heart and soul of the airplane.” Automation on the Pegasus has rendered the flight engineer role obsolete, while enhanced communication systems make the KC-46 well-suited for the modern battlefield.

I returned to Travis Air Force Base for Excalibur’s retirement ceremony on September 26, 2024—the day it was decommissioned and flown to Davis-Monthan Air Force Base in Arizona. The ceremony was a heartfelt gathering of current and former air crews, along with dedicated mechanics who had supported the KC-10 throughout its history. 

“How do you say goodbye to a legend?” wonders Baer. “We’re the last in a long line of truly meritorious service, surrounded by wonderful people who have cared for and operated this jet with resolve and tremendous appreciation.”

Excalibur basked in the California sun, adorned with the tanker’s original nose art of a knight and charging dragon. Generals and colonels shared personal anecdotes, emphasizing the spirit of the KC-10 and the crews who operated it. “It’s not just about the statistics,” says Johnson. “It’s about the people.” 

During Excalibur’s retirement flight, it circled the base on a low pass, escorted by two F-15Cs from California’s Air National Guard 144th Fighter Wing. The three-ship formation symbolized decades of partnership between tanker and fighter. Suddenly, Excalibur climbed steeply, creating a bittersweet moment that displayed the KC-10’s power and grace one last time for the crowd of admirers below. 

Alan De Herrera is an independent photojournalist and writer who covers stories about humanitarian operations, the military, and aerospace.

This article, originally titled "Excalibur's Final Mission," is from the Summer 2025 issue of Air & Space Quarterly, the National Air and Space Museum's signature magazine that explores topics in aviation and space, from the earliest moments of flight to today. Explore the full issue.

Want to receive ad-free hard copies of Air & Space Quarterly? Join the Museum's National Air and Space Society to subscribe.