The KC-46 is better known for how it was bought than for anything it has done, because the tanker competition became one of the longest procurement fights in American defence history. The 2003 lease was meant to be a quick way to get new tankers without a large up-front payment, but critics in Congress, led by Senator John McCain, argued that it would cost far more than buying the aircraft outright. Then came the revelation that Darleen Druyun had favoured Boeing while discussing employment with the company. The lease was dropped and the Air Force had to start again.

The 2008 decision in favour of the Northrop Grumman and EADS KC-45A, based on the Airbus A330, was a political shock in the United States, and Boeing’s protest found that the Air Force had not evaluated the bids according to its own rules. In the third competition, run in 2010 and 2011, Northrop withdrew and EADS bid alone. Boeing won on price. The irony is that the A330 tanker went on to sell widely outside the United States as the A330 MRTT, while the KC-46 has so far found only two export customers.

Japan already flew four Boeing KC-767J tankers, an earlier 767 tanker built for the Japan Air Self-Defense Force and Italy, and chose the KC-46A as its next tanker. Its aircraft serve alongside the earlier 767s, refuelling F-15J, F-2 and F-35 fighters and providing long-range transport.

Israel ordered four KC-46As in 2022 to replace its ageing Boeing 707 tankers, which had supported Israeli long-range strikes for decades. The first Israeli aircraft were delivered in 2026. Italy, which also flew KC-767s, considered the KC-46 but in 2026 chose the Airbus A330 MRTT instead.

The small export tally is a point of pride for Airbus and a sore one for Boeing. Most countries choosing a new tanker since 2010 have preferred the larger A330, with its greater fuel load and cabin, while the KC-46 has sold mainly on its close fit with US Air Force equipment, training and support. For allies that operate American fighters and want to plug into US logistics, that commonality is a real advantage. For Japan, it also meant a tanker that could work smoothly with US Air Force units in the Pacific during exercises and crises, and for Israel one that matched its F-15 and F-35 fleets.

• KC-767A: Boeing’s first 767 tanker, four built for Italy, delivered from 2011.
• KC-767J: four for Japan, delivered from 2008.
• 767-2C: the provisioned freighter airframe built on the Everett line and converted into a tanker; first flight December 2014.
• KC-46A Pegasus: the US Air Force tanker, also bought by Japan and Israel; first flight September 2015.

Boeing won the KC-X competition partly on price, and the development contract was fixed-price: anything over the agreed amount came out of Boeing’s own pocket. Wiring redesigns, fuel system changes, the debris problems of 2019, cargo lock defects and the redesign of the boom and the Remote Vision System all added cost. Through the late 2010s and early 2020s Boeing reported repeated charges against the programme, and press tallies of its total losses run to several billion US dollars, well above the value of the original development contract.

For the Air Force, the attraction is running cost. The KC-46 uses two engines instead of four, and Boeing claims that four KC-46s cost about as much to operate as three larger tankers. Exact hourly costs depend on what is counted and have not been published in a consistent way, so any figure should be treated as an estimate.