The Air Force’s aerial tanker fleet is running full out. Tanker aircrews are routinely deployed more than 200 days a year, and their aircraft are constantly on the go, extending the range or staying power of virtually every type of aircraft in USAF’s inventory.
Aircrews and maintainers say they can meet the required pace, but they worry openly that this perpetual motion machine, filled with aged aircraft, will develop an unexpected fault that would not only ground the airplanes but slow USAF global operations to a crawl.
“We never want to get to [a] catastrophic failure of our refueling business,” Gen. Arthur J. Lichte, commander of USAF’s Air Mobility Command, said in a September speech. Lichte noted that tankers are involved in practically all aspects of USAF air operations, but are the oldest aircraft in the fleet, some clocking in at 50 years old.
“It’s tragic that we have people working on 50-year-old airplanes,” Lichte said, making a pitch to persevere in replacing the tankers. “We’ve just got to get on with it.” Without tankers, he said, the reach or persistence of almost every flying system in the service would be vastly shortened.
Lichte said that AMC needs at least 520, and possibly as many as 640, tankers. However, he said, with recent early retirement of all KC-135Es, “we only have 474 tankers, so there is a readiness gap” in the fleet.
A KC-135R tanker lands at Manas Transit Center, Kyrgyzstan, after a refueling
No Spring Chicken
The Air Force has 415 KC-135 Stratotankers, which date back to the Eisenhower Administration, and 59 KC-10 Extenders, brought in during the Reagan Administration. The KC-135s still in the inventory all had the Pacer CRAG (compass, radar, and GPS) update in the 1990s and, among structural and other improvements, swapped old engines for more powerful and efficient new ones.
However, even the 25-year-old KC-10 is “no spring chicken,” Lichte said, “and by the way, we haven’t done anything ... to modernize it. It has about the same equipment that it had when it first rolled out in 1981.”
Despite the age of the equipment, though, the Air Force is operating the KC-10 at full speed, maintaining a punishing pace of tanker operations worldwide.
To support operations in Southwest Asia, active duty tanker aircrews typically deploy to a base in the region for two months at a time and then return to their home base for two months—what is known as a “one-to-one dwell time.”
“Two months is about as long as we can be over there because we fly quite a bit and we run out of our flying hours,” explained Capt. Ryan T. Garlow of the 22nd Air Refueling Wing at McConnell AFB, Kan.
He said tanker pilots are limited to about 125 hours of flying time per month under a policy that mirrors Federal Aviation Administration safety standards. Above that number, aircrew proficiency begins to deteriorate “from [flying] too much and too often,” he said.
“So, we go over there and fly our hearts out until we’re all maxed out, and then come home,” he said. However, the respites stateside are no vacation, since pilots are expected to use that precious home stay to upgrade their status—to aircraft commander or flight instructor—get their professional military education, and still fly missions within or from the continental US in support of USAF’s other commitments for aerial refueling.
The pace is toughest on new pilots, he said, noting that they can “easily” be deployed to the Central Command theater of operations for three deployments totaling 180 days a year, not including other deployments when based at home. More senior pilots in KC-135s pull a bit less CENTCOM duty, since they have leadership responsibilities at the home base. Garlow said that in the last three years, he averaged 200 days of temporary duty.
The KC-135s and KC-10s typically deploy to a base in Southwest Asia (the Air Force declines to identify its overseas tanker bases) from which they can support operations over both Iraq and Afghanistan. Once in-theater, the aircraft belong to Air Forces Central, and the combined air and space operations center (CAOC) directs how the tankers will be used, published in the daily air tasking order.
“It’s 99 percent tanking,” Garlow said of the missions, the other small percentage being short-haul cargo flights. KC-135 aeromedical evacuation missions are also typically run on a weekly basis, but the aircraft can perform air refuelings as it transports patients.
“The details are different every day,” he said, adding, “I get to see every part of the Air Force.” Missions vary from refueling intelligence-surveillance-reconnaissance aircraft to topping off cargo airplanes to supplying fuel to fighters transiting back and forth to supporting an unfolding ground battle.
A KC-135 from the Pennsylvania Air National Guard’s 171st Air Refueling Wing tops off an F-15 during an Operation Noble Eagle combat air patrol mission over Washington, D.C.
Patience Is Vital
In such circumstances, tankers will often fly high above where the fighters are providing close air support to troops in contact on the ground, and the fighters will climb to the higher altitude to refuel, then descend back to battle altitudes. This is possible in Afghanistan and Iraq, Garlow said, because of the low threat posed by enemy forces against USAF aircraft. If the enemy has more sophisticated anti-aircraft capabilities, the tankers would orbit just out of range of the threats, and the fighters would have to depart the threat zone to refuel.
The CAOC does a good job at managing what are called “ad hoc” missions, Garlow said, in which a fighter or other asset has been called to deal with a troops-in-contact situation. Only rarely will a tanker crew, on its own initiative, move in to supply gas in extremis.
“Unless we feel it’s an emergency situation ... and we need to make that decision on our own, we let the CAOC make decisions as to priority. They have the bigger picture.” After years of operations in Southwest Asia, “they can foresee those kinds of things.”
There are a limited number of KC-135s that can themselves receive fuel air-to-air, in addition to providing it, and McConnell has eight of those aircraft, Garlow reported. In one incident, his aircraft was getting ready to depart the operations area, but an airfield suddenly closed due to weather, stranding a number of airborne aircraft already low on fuel.
“I had to turn around, get my own gas—because I didn’t have the gas to give them—and then drop down and give them gas as quickly as we could,” he said.
Garlow said that maintenance issues on the KC-135 require “patience,” and that it’s become a habit for pilots to show up for a preflight inspection more than an hour-and-a-half early to deal with maintenance issues.
“I would say, 90 percent of the time, I go out there [and] there’s always at least one little thing that’s not working,” he said.
Sometimes, especially when the mission is urgent, the aircraft will launch with some maintenance issues unresolved, but which aren’t critical to the mission. Maintenance problems have grown over time, though, said Garlow, who noted that it’s par for the course with such an old aircraft. He added that maintenance crews in the field have to work especially hard to keep the KC-135 up to snuff.
He noted that his grandfather, now age 82, flew on the KC-135 as a navigator when it was brand-new. His grandfather is “still surprised” that Garlow is flying the same airplane.
The operating tempo is similar, if slightly tougher, for KC-10 pilots, according to Maj. Terry Tyree, a KC-10 pilot with the 305th Air Mobility Wing at Joint Base McGuire-Dix-Lakehurst, N.J.
Tyree said that the greater size of the KC-10 versus the KC-135 makes it an in-demand asset for some missions, because it can carry more fuel. He and other KC-10 pilots typically deploy for 70 days at a time, or 210 days a year. The fact that there are only 59 KC-10s in the inventory makes the system even more of a high-demand asset.
The KC-10 is “one of the busiest airframes in AMC,” Tyree said. In the last few years, he said more than 98 percent of his missions have been over Afghanistan. The KC-10s don’t do the aeromedical evacuation mission, but up to 18 KC-10s per day will be in the skies of CENTCOM’s area of responsibility.
Missions typically last eight to nine hours, Tyree said, but in the winter months, missions will last two or three hours longer. That’s because the aircraft can take off with more fuel in cooler temperatures, allowing it to stay aloft longer and refuel more aircraft. As a result, there’s a slight reduction in the demand for KC-10s in winter, since the same amount of refueling can be accomplished with fewer aircraft.
Sam Wilkins, a protective-coating technician, preps a KC-135E Stratotanker for preservation and storage at Davis-Monthan AFB, Ariz. The Air Force recently sent the last of its ancient E model KC-135s to the Boneyard.
Never an Empty Trip
In theater, both the KC-135 and KC-10 can refuel any aircraft that comes up for gas, but in the KC-135’s case, it must be configured for the type of mission it’s flying. Air Force aircraft mainly refuel via the flying boom at the back of each tanker. The boom is a steerable spigot, operated by an enlisted crew member, that can pump gas at very high speed into a receptacle on the other airplane. However, Navy and many coalition aircraft use the probe-and-drogue method, in which a probe extends on the receiver aircraft and connects to a basket on the end of a hose deployed from the tanker. Probe-and-drogue-equipped aircraft can’t take fuel from a boom, and can’t receive fuel at the same high rate as boom-capable aircraft.
The KC-135 can only supply fuel through the boom, but with a special attachment on the boom, it can reel out a drogue. The KC-10 has both a drogue hose and the boom on its centerline, but it can pump gas through only one system at a time.
The Air Force has a limited number of wing air refueling pods, or WARPs, which can be mounted on the wingtips of KC-135s or KC-10s to allow probe-and-drogue refueling from both wings simultaneously, but these are not currently deployed in-theater.
The KC-10’s flexibility makes it “a sought after platform,” Tyree said. “We can take off in a matter of minutes and do one [refueling method] or the other.”
A NATO-standard manual on air refueling has simplified communications between USAF boom operators and foreign pilots, Tyree said. Previously, communications could be a challenge because of the language differences among coalition aircrews.
Tankers are cycled in and out of the theater, just like the crews, so that a limited number of airframes don’t rack up excessive numbers of hours.
On the way to a theater—or on the way home—KC-10s will usually carry both some passengers and some essential cargo, such as fighter engines that need maintenance at home station. The aircraft on such “redeployer” missions never make the trip empty.
After less than two months back at home base—in the KC-10’s case, either Travis AFB, Calif., or McGuire—it’s back to the desert again.
“Everyone in our squadron is in this rotation,” Tyree said. Supporting CENTCOM’s needs is “a no-fail” requirement.
A B-52 takes on fuel from a KC-135 over the Pacific Ocean during an exercise. Both aircraft types were first fielded in the 1950s.
“So, we get what bodies and the rotational basis that we need to fill that, and then ... everyone that’s left here stateside is used to support the other AMC missions.”
Those missions are run out of the 618th Tanker Airlift Control Center at Scott AFB, Ill. They encompass all of the other refueling activities required of USAF, from supporting cargo missions across the oceans to fighter movements, bomber practice, humanitarian relief, and support of exercises.
Priority for refueling missions is set by a new Joint Chiefs of Staff priority system, according to Lt. Col. Christy Kayser-Cook, chief of air refueling requirements at the 618th TACC.
“It was signed and became effective 1 October,” said Kayser-Cook, who said that tanker priorities had never been governed by such a document before. The missions with first claim on tankers are “Presidential support and contingencies,” while secondary priority is given to “exercises and ... other high-level moves.” That’s because the latter can be delayed or shifted, whereas fighting missions and Presidential movements usually cannot.
Kayser-Cook said that tankers are used to the maximum extent possible, so that there is rarely a “deadhead” tanker which is simply returning from a mission with no refueling tasks or cargo aboard.
When requests for a tanker mission overseas come in, the first step is to see if Pacific Air Forces or US Air Forces in Europe—which have some tankers “chopped” to them—can do the job, Kayser-Cook said.
US Transportation Command “works with PACAF and EUCOM [US European Command] to globally manage the tankers that are out there,” she said. If there are tankers available, they’ll be used first “before we send tails from CONUS.” If no aircraft are available, a continental US-based tanker will have to be dispatched.
The TACC schedules “fighter drags,” which involve the deployment of fighters, usually across oceans, and these operations are among the “biggest stressers,” Kayser-Cook noted, because fighters require a lot of fuel, and need escort by several tankers. Sometimes they will be accompanied the whole way by the same tankers; at other times, a series of handoffs is arranged.
She noted that the Thunderbirds aerial demonstration team, touring the Pacific in the fall, needed constant refueling support, but rather than assign a tanker to simply travel with the team, aircraft were dispatched only at movement times, to avoid having a tanker sit somewhere for a couple of days, idle.
The TACC helps organize tankers to support big exercises such as Northern Edge. Although Northern Edge is a PACAF exercise, PACAF doesn’t have enough tankers to meet the need, so others must be found.
Noble Eagle homeland defense missions are not handled by the TACC; they have a separate reporting line, and “about 95 to 98 percent of those missions are handled by the Guard and Reserve,” she noted.
A KC-10 takes off from an air base in Southwest Asia on a refueling mission. Up to 18 KC-10s fly missions over the CENTCOM war zone every day.
Our Biggest Concern
When departing the US, usually from the East Coast, Kayser-Cook said cargo aircraft such as C-5s and C-17s will be refueled on the outward leg by tankers from the Northeast Tanker Task Force, a string of mainly Guard bases throughout the mid-Atlantic and New England states. Sometimes the aircraft will need a KC-10 to escort it; usually, a KC-135 will give fuel, then return to base. Sometimes they orbit over the Atlantic, ready to refuel aircraft returning from Europe and Southwest Asia.
Over Europe, tankers are usually dispatched from Ramstein AB, Germany, and for the final refueling prior to entering the CENTCOM area of operations, tankers will often be mustered from Incirlik AB, Turkey, which also provides tanking for aircraft over the Mediterranean Sea. The Incirlik Tanker Task Force works for EUCOM, not CENTCOM. One other tanker task force is located in the Pacific region, but Kayser-Cook declined to specify its location.
Kayser-Cook said that she has felt no impact from the Air Force’s early retirement (for safety reasons) of KC-135Es over the past year, and that most of her tanking needs can be met with assets on hand, or through activations or volunteerism from the Guard and Reserve.
“We couldn’t do it without [them],” she said, noting that the Northeast Tanker Task Force is “pretty much all Guard.”
While she has not seen any dramatic strains on the tanker fleet as a result of its high operating tempo, Kayser-Cook said she pays close attention to maintenance issues on both the KC-135 and the KC-10.
The KC-135 is “our biggest concern right now” because of its age, and the worry that “there will be maintenance issues that could possibly take down the whole fleet.” She also said she worries that maintenance problems will start to affect departure reliability for the KC-135.
“Barring any huge maintenance issues,” though, “I think we can sustain what we’ve got for a given amount of time,” Kayser-Cook asserted. Much of that optimism depends on the continued ability of the Guard and Reserve to sustain their contribution to the tanking effort, she said.
“If that keeps up the same, then yeah, we can sustain what we have right now,” she said.
However, “we’re definitely going to need a new tanker at some point,” she said.
How Best To Extend the Extender
Maintaining the KC-10 is different than it is for the KC-135, according to Col. James Fulton, head of the 727th Aircraft Sustainment Group at Tinker AFB, Okla.
The KC-10 is repaired under contractor logistics support. It’s a larger airplane, and that brings its own set of problems. However, the pace of operations is starting to make the Extender tired, Fulton said.
“Carrying those increased fuel loads, taking off at max weight, is causing stress on the aircraft landing gear systems,” he noted. The longer flight hours are also “putting increased wear and tear on the engines.”
The KC-10 was planned to operate about 52,000 hours per year, but has been averaging 68,000 to 71,000 hours per year since 2001.
Air Mobility Command plans to keep the KC-10 in service for another 35 years.
Costs are being held down by adopting commercial air carrier practices that stretch the intervals between the least arduous checks. That has yielded the equivalent of three extra aircraft in service at any time. However, expanding the interval on the light checks means that the more in-depth inspections will take longer, meaning its depot days will begin to lengthen, from 18 to 20 days, Fulton noted.
The KC-10 has never had a major modification, but it will get an upgrade to its boom control system, now on contract but not yet being installed. The cockpit will also get a number of multifunction displays. It will get the Global Air Traffic Management capability so it can travel in the most efficient air routes and operate unrestricted from bases worldwide.
Care and Feeding of the Stratotanker Fleet
Keeping the KC-135 healthy is a big job, and it’s getting harder all the time.
In the 1990s, there was a dramatic run-up in the number of days KC-135s spent in depot. Problems discovered there had to be fixed before the aircraft could go back into service, and time the aircraft spent sidelined for repairs grew to 400 days by 2000. A different repair philosophy, increased inspections, and production line efficiencies drove depot days down to just 180 by 2007, but the stays are starting to creep up again, and now average about 220 days.
The reason, according to KC-135 specialists at Oklahoma City Air Logistics Center at Tinker AFB, Okla., is that the easy problems have all been fixed. What’s left to handle are tougher problems in corrosion and structural fatigue.
“Every patient is unique,” said Col. Robert Torick Jr., commander of the 827th Aircraft Sustainment Group at Tinker. There are no typical problems afflicting the fleet; they present in different combinations every time.
The biggest project pending on KC-135s is installing the Block 45 upgrade, which will provide a “digital backbone” for the aircraft and make it fully compliant with Global Air Traffic Management requirements, permitting the Stratotanker to fly in the most favorable airspace. It should be completed in 2021.
Tinker has been given marching orders to keep the KC-135 viable until 2045, Torick said, and he believes it can be done, but will grow more costly all the time. The price tag per depot visit currently stands at about $8 million per aircraft, every five years.
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