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Boeing’s KC-46: U.S. Air Force’s Problematic New Refueler

The first KC-46A Pegasus lands at Seymour Johnson Air Force Base, North Carolina, June 12, 2020. The KC-46A Pegasus is a widebody, multirole tanker that can refuel all U.S., allied and coalition military aircraft compatible with international aerial refueling procedures. (U.S. Air Force photo by Senior Airman Jacob B. Derry)

The Boeing KC-46 Pegasus refueler only recently entered service with the U.S. Air Force, which intends to procure 179 of them by 2027. Yet multiple design problems have placed the future of the airframe in peril. The problems are so profound that the Government Accountability Office has warned the Air Force to reconsider its purchase of the KC-46. 

“The Air Force now plans to commit to the new design…before all of the technologies are adequately developed – risking further delays and increased costs,” the GAO report cautions, “our recommendations to the Air Force include that it fully assess and test the KC-46 technologies.” 

In other words, make sure the thing works before you buy it. 

A Reliable Predecessor

The KC-46 Pegasus is a modified version of the Boeing 767. The airframe was designed as a replacement for another Boeing build, the aging KC-135 Stratotanker. The KC-135 first entered service during the Eisenhower administration, in 1957, and it has been used reliably ever since. The refueler’s planned replacement, on the other hand, has been a debacle.   

For starters, the Pegasus’ Remote Vision System, or RVS, does not work. This is a problem. The RVS is a network of cameras and sensors that boom operators use to maneuver the refueling boom into other aircraft. The system is vital for refueling operations, which are of course the KC-46’s primary function. In 2021, Boeing spent $406 million fixing the faulty RVS. Older tankers like the KC-135 and KC-10 don’t have an RVS system. They instead rely on a window. 

The RVS isn’t the only thing Boeing has had to fix; cost overruns now exceed $5.4 billion.  

A Litany of Problems With the KC-46

The KC-46 also suffered a series of setbacks related to its Auxiliary Power Unit, or APU. First, the APU duct clamps were becoming loose or cracked. Second, the APU’s drain mast, which was not properly welded, tended to come loose during flight. The duct clamps were redesigned and retrofitted. A new and improved drain mast is still being tested. 

In-air refueling tests revealed further problems in the KC-46. A 2015 test had to be aborted when the KC-46’s refueling boom produced higher-than-expected axial loads while refueling a C-17 transport plane. Apparently, the problem resulted from the turbulent bow-wave effect, a phenomenon caused by two large aircraft flying in a line. Fixing the problem cost $835 million.

In 2020, the Air Force became aware of chronic leaks in the Pegasus’ fuel system. Aircrews discovered fuel moving between the primary and secondary fuel protection barriers. It was one more problem in what appears to be a chronically flawed project. Fifty-seven KC-46s are already in service. But because of the persistent, numerous defects, the aircraft will not be combat-ready for another few years, leaving the Air Force searching for ways to use their new tankers. 

“As I look over the 10 years, I have to say…right now where we’re at in the program is we’re making lemonade out of lemons,” Air Force Gen. Jacqueline Van Ovost, head of Air Mobility Command, said in 2021. “We are exploring limited operational capability for the KC-46.” 

The program is already years behind schedule, and the Air Force is only accepting delivery of two KC-46s per month. With the GAO cautioning against further KC-46 procurement, the future of the program seems to be in doubt. 

 Harrison Kass is a Senior Defense Editor at 19FortyFive. An attorney, pilot, guitarist, and minor pro hockey player, he joined the US Air Force as a Pilot Trainee but was medically discharged. Harrison has degrees from Lake Forest College, the University of Oregon, and New York University. He lives in Oregon and regularly listens to Dokken.

Written By

Harrison Kass is a Senior Defense Editor at 19FortyFive. An attorney, pilot, guitarist, and minor pro hockey player, he joined the US Air Force as a Pilot Trainee but was medically discharged. Harrison has degrees from Lake Forest College, the University of Oregon School of Law, and New York University’s Graduate School of Arts & Sciences. He lives in Oregon and regularly listens to Dokken.



  1. jeff

    June 9, 2022 at 6:33 pm

    How come we can build planes in the 50’s that work and we cannot do it today when we are supposedly more technologically advanced? Are we trying for too many bells and whistles or are we incompetent? NASA spent millions to make a pen that writes in space, the Russians used a pencil.

  2. Curtis Conway

    June 10, 2022 at 6:58 pm

    Every program experiences problems when newly introduced. At least Boeing is paying for their mistakes, or lack of an originally solid engineering solution for their problems discovered, and those solutions are rock solid. If we started over with the Airbus A330 MRTT (KC-30A) . . . for the most part . . . we would be starting all over again.
    The KC-30A is not a USAF MIL-STD airframe and systems, and those who suggest it is need only concede it will not currently pass an EMP test at Naval Air Systems Command’s NAS Patuxent River EMP test facility. We would literally be . . . starting all over again . . . giving up a platform THAT IS NOW 97% mission capable as of this last week.
    RVS 2.0 is under test and solves not only the aircrafts vision problems but provides solution to other issues concerning autonomous tanking. Most of this tankers refueling capability is digitally controlled and that lends to many follow-on capabilities.
    The actual effectiveness of the KC-46A Pegasus Tanker platform is proving its metal having been built upon the ubiquitous Boeing 767 airframe, and if far more capable than KC-135 Stratotanker it replaces. The KC-46A aircraft from the USAF’s 22nd Air Refueling Wing conducted a flight between 13 and 26 November that was a 13-day trip marking the first global circumnavigation of the globe for the type.
    Boeing invested in five development labs that support development of various platform systems, and they continue to be used for follow-on improvements. This investment is not insignificant, and the USAF is keen on taking full advantage of them.
    The USAF may very well build upon the mounting successes of the platform and just continue to purchase them instead of holding an KC-Y competition as a Risk Reduction Measure, and be wise to do so.

  3. Jordon Berkove

    July 11, 2022 at 1:01 am

    Curtis, Those are certainly nice thoughts about the KC-46. As the Airbus is serving Europe without issues and our KC is unable to use it’s boom effectively in less then optimal lighting. Being more EMP hardened does not help line up a receptacle you can’t see. Using the eyeball 1.0 as they do in the KC30 is effective. When our own government accounting office suggests making sure everything is fixed before proceeding, why would you support this we’ll fix it as they’re made? This is what caused the failure of the F35.

  4. Jordon Berkove

    July 11, 2022 at 1:08 am

    To correct my above comment. Lockheed has worked with Airbus and does use remote vision. However unlike the Pegasus the A330 works correctly and also carries more fuel. Currently there’s a push to stop production of the Pegasus and get Lockheed/Airbus 330 to meet our needs

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