The C-17 fleet surpassed 4 million flying hours on Jan. 15. USAF's 222 C-17s, and 53 others owned and flown by nine nations, are the go-to airframe for global airlift. A long series of planned upgrades looks to keep the Globemaster III relevant and flying into the 2060s. Staff Sgt. Christian Sullivan
Photo Caption & Credits

Master of the Globe

April 23, 2021

As the Globemaster III racks up its 4 millionth flight hour, planners ready upgrades and begin to imagine what comes next.

On a chilly January morning, Airmen piled into C-17 tail No. 99205 at Joint Base Charleston, S.C., and took off for a rendezvous with history. Not long after takeoff, the jet joined up with a KC-46 Pegasus tanker and logged the 4 millionth flying hour for the unique airlift, a plane that began as a case study for acquisition failure and transformed, over nearly three decades, into the backbone of U.S. military airlift. 

“This is a significant milestone for the program,” said Col. Scott Ekstrom, Air Force Life Cycle Management Center C-17 System Program Manager. “It is truly a testament to the dedication and hard work that has gone into producing and keeping the C-17 fleet operational and effective over the years. It has been a team effort, everyone who has supported the C-17 fleet should take pride in this milestone.”

We’re optimistic on analysis, but this requires continuing study for what we would have to do to that airplane.Gen. Jacqueline Van Ovost, AMC commander

The Air Force’s 222 C-17s are the major portion of a global fleet of 275 aircraft flown by nine nations, including an international consortium. They are the go-to airframe to transfer personnel and materiel to combat zones and remote locales around the world, enduring conditions from dirt airstrips in the Syrian desert to ice and snow in Antarctica. 

Today, Air Mobility Command (AMC) anticipates keeping “the Moose” relevant out to around 2060, while it develops requirements for a “family of systems” that someday will replace it. 

From Failures to Success

The C-17 dates back to the initial award for a “C-X” airlifter to McDonnell Douglas in August 1981, with the company basing its projected new plane on its YV-15 demonstrator. McDonnell promised a low-risk design based on proven technology. 

It wasn’t long before turbulence struck. The requirement to land on short airstrips and to back up on a runway while also serving as a strategic airlifter carrying M-1 battle tanks and other equipment over vast distances complicated development. Flight control and wing design issues emerged. 

Before long, Congress and the Pentagon threatened to cancel the program outright. Military and industry leaders were fired. Boeing, which would eventually buy McDonnell Douglas, offered an alternative: a militarized 747-400F, called the C-33. Lockheed Martin offered an updated version C-5 variant. 

Gen. Jacqueline D. Van Ovost, now commander of Air Mobility Command, was a test pilot working on the C-17 demonstration in those early days. She became chief of the C-17 Acquisition Branch and C-17 Program Element Monitor. The program was “being battered around as a waste of money,” she recalled recently. Deficiencies were rampant.  

In 1994, USAF and McDonnell Douglas struck a deal to fix the problems. USAF spent more and altered requirements. 

“Everybody put their nose to the grindstone,” Van Ovost recalled in an interview with Air Force Magazine. “We were kind of given an ultimatum, and we produced. We saw real gains met, so we leveraged everything we could, and we turned that airplane around.”

The USAF team focused on concurrently conducting initial operational test and evaluation and developmental test and engineering, with the aim of fixing problems quickly.

Flight-tests focused on aerial refueling, dirt operations, low-altitude operations, and combat-style airdrops, the major challenges. The unique capacity and rugged nature of the C-17 meant it soon became the backbone of mobility operations supporting operations in Iraq and Afghanistan and all around the globe. Those challenging capabilities demanded in the 1980s and ’90s were right in tune with actual demands in the 2000s. 

“To turn around and watch us use it in combat was very, very satisfying for me,” Van Ovost said. 

Today, she sees parallels with the challenges and struggles she endured with C-17 and today’s poster child for troubled mobility aircraft, the KC-46. “When I got on the program, the C-17 was being battered around as a waste of money on the Hill. That was a time when we only had 40 airplanes on contract. And I stayed with that program for five or six years and in that period, we turned it from, you know, the joke, to we signed our first multiyear [contract] for the 120 airplanes because of the turnaround. … Frankly, it had more “Category One”—or the worst kind of deficiencies—than this airplane does.”


The last USAF C-17 was delivered in 2013; two years later, the fleet logged its 3 millionth hour, and Boeing, having long before acquired McDonnell Douglas, delivered its last C-17 and closed the Long Beach, Calif., production line. 

“The C-17 is a robust, solid platform that can get in and out of airstrips with significant cargo better than any airlifter out there,” Ekstrom said. “We are seeing that the aircraft can fly longer than its initial design—but not without updates and modernization.”

As C-17s go into depot maintenance, crews will replace the legacy Head-Up Display with a new one that will increase field of view, among other near-term upgrades. Here, Maj. Adam Sugalski and 1st Lt. Matthew LoPresti fly a C-17 Globemaster III. Staff Sgt. Stephanie Serrano

Near-Term Upgrades

All 275 C-17s, both USAF and international, completed the Block 21 upgrade in 2020. The update included the required Automatic Dependent Surveillance-Broadcast Out transponder system, required by both the Federal Aviation Administration and European authorities for aircraft in controlled airspace. Additional upgrades included an Identification/Friend or Foe capability, plus other communication and navigation software.

USAF teams worked to complete the update at five U.S. locations and deployed to five others internationally to complete the upgrades on schedule, said Jim Ross, primary Block 21 retrofit manager in the C-17 Program Office, according to a release. The entire process took about two years. 

As C-17s rotate into depot maintenance, the C-17’s legacy Head-Up Display system will be replaced, with the new system providing increased field of view, contrast ratio, and resolution, Air Mobility Command reports.

Beginning in 2023, legacy ARC-210 third-generation radios will be replaced with new sixth-generation radios including the Integrated Waveform, Mobile User Objective System voice, and second-generation anti-jam tactical UHF Radio for NATO (SATURN), which will replace the HAVE QUICK II system for all military services in October 2024. The new frequency-hopping radios are resistant to electronic counter measures, according to AMC. 

Data link satellite systems also are being replaced as the Inmarsat I-3 communication satellites are reaching the end of their lives; AMC will do those upgrades at the same time to reduce cost and downtime.

“AMC will continue to research and prioritize modernization of our workhorse C-17 fleet as new requirements emerge,” said AMC spokesman Capt. Christopher J. Herbert.

But AMC is also revolutionizing the C-17’s ability to fight. An Air Force Advanced Battle Management System (ABMS) on-ramp demonstration in 2020 proved the C-17 can deploy weapons when a C-17 dropped a Joint-Air-to-Surface Standoff Missiles using a roll-on pallet. 

“Why wouldn’t we change the calculus by doing different things, moving away from the antiquated view that AMC just brings stuff when they’re called?” Van Ovost said. C-17s can “be a maneuver force inside the threat ring,” she added. “Instead of dropping them on a ramp somewhere at some island, we’re just dropping them in the sky,” Van Ovost said. “And after they drop out of the sky, someone else lights them off and takes them to the target.” 

AMC is planning in future demonstrations to launch attritable systems, like the Gremlin developed by the Defense Advanced Research Projects Agency. The small, unmanned aircraft could be useful in both offensive and defensive counter-air operations. 

And with the C-17’s wing-mounted hardpoints, Van Ovost said, it is “not a stretch to think that we could put one or two missiles on there for self defense.” 

In another 2020 ABMS demonstration, a C-17 helped a Marine Corps High Mobility Artillery Rocket System with targeting. The C-17 flew to its destination, the HIMARS was rolled off and fired, then was rolled back on so the C-17 could take off again in a “shoot-and-scoot” maneuver.


To keep the fleet healthy, AMC is applying conditions-based maintenance practices used for the C-5 and C-130 fleets to better predict parts failures with an eye toward increasing Globemaster readiness. The command has explored rotating airframes from high operations tempo units to lower op-tempo units to keep wear and tear even across the fleet, and likewise rotate units from high-moisture and high-salinity environments to more arid climates, in a bid to minimize structural corrosion. 

“We’re optimistic on analysis, but this requires continuing study for what we would have to do to that airplane,” Van Ovost said. “So I’d say that we are cautiously optimistic about the life span of the airplane.” 


The 2018 “Air Force We Need” called for 386 operational squadrons, including three more C-17 squadrons—or the equivalent—by 2030. But the option to buy or build more C-17s has long since passed. The cost to reconstitute the C-17 production line would be prohibitive. 

But adding more is not be necessary, a 2018 Mobility Capabilities and Requirements study argued. It concluded existing strategic airlift is adequate to meet future needs. The Center for Strategic and Budgetary Assessments, in a congressionally mandated report released in 2019, recommended maintaining the C-17 fleet and ensuring readiness levels remain high as the best way forward.

A new Mobility Capabilities and Requirements Study could be released this year. 

The C-17 fleet is about 20 years old on average, making it among the newest and healthiest airlifters in the USAF inventory. The mission capable rate was 82.23 in 2018 , according to USAF figures.

Long-Term Plans

AMC is beginning to think about what a C-17 replacement might look like 20 to 40 years down the road. A “family of systems” are conceived as one way forward, with wargames starting to flesh out “what capabilities I’m asking for,” Van Ovost said. “When I work with the Marine Corps and the Army, what is it they need to transport? What types of timelines? What kind of capabilities and where might they be positioned?” 

The tactics tested in the ABMS events could help point to what those needs might be, as will exercises and wargames with the Army and Marine Corps to build out what a future force would require.

“I don’t just think volume, I also think of the ability to do things inside of that contested zone,” Van Ovost said. “How do you think small, as well? [Aircraft] that can fly off … and bring a capability forward to say [Air Force Special Operations] or to the Army when they need it? … That’s how we’re going to tweak the attributes necessary for the next … kind of a combined C-5, C-17.” 

Such an aircraft might employ stealth, or could be optionally manned; it could leverage capabilities developed for the B-21 Raider and the digital engineering and modelling attributes of the eT-7A Red Hawk, or even the highly secretive Next-Generation Air Dominance fighter platforms. 

“It’s hard to say what’s going to happen,” Van Ovost noted. The horizon is still far off, measured in decades, not months or years. “It’s really pretty far out there to think about the full replacement of the C-17.”

The Globemaster III will be a stalwart for years to come.

A Globemaster III delivers Marines assigned to Delta Battery, 2nd Battalion, 14th Marine Regiment, to Fort Bliss, Texas, in 2020. Two M142 High Mobility Artillery Rocket Systems (HIMARS) and other support vehicles traveled as one package inside the Boeing C-17 Globemaster III for the ABMS training. Pfc. Elijah Ingram/USA