KC-X in the context of Airbus A330-200

The Airbus A330 is a wide-body airliner developed and produced by Airbus.Airbus began developing larger A300 derivatives in the mid–1970s, giving rise to the A330 twinjet as well as the Airbus A340 quadjet, and launched both designs along with their first orders in June 1987. The A330-300, the first variant, took its maiden flight in November 1992 and entered service with Air Inter in January 1994. The A330-200, a shortened longer-range variant, followed in 1998 with Canada 3000 as the launch operator.

The A330 shares many underpinnings with the airframe of the early A340 variants, most notably the same wing components, and by extension the same structure. However, the A330 has two main landing gear legs instead of three, lower weights, and slightly different fuselage lengths. Both airliners have fly-by-wire controls as well as a similar glass cockpit to increase the commonality. The A330 was Airbus's first airliner to offer a choice of three engines: the General Electric CF6, Pratt & Whitney PW4000, or the Rolls-Royce Trent 700. The A330-300 has a range of 11,750 km (6,340 nmi; 7,300 mi) with 277 passengers, while the shorter A330-200 can cover 13,450 km (7,260 nmi; 8,360 mi) with 247 passengers. Other variants include the A330-200F dedicated freighter, the A330 MRTT military tanker, and the ACJ330 corporate jet. The A330 MRTT was proposed as the EADS/Northrop Grumman KC-45 for the US Air Force's KC-X competition, but lost to the Boeing KC-46 in appeal after an initial win.

The Boeing KC-46 Pegasus is an American military aerial refueling and strategic military transport aircraft developed by Boeing from its 767 jet airliner. In February 2011, the tanker was selected by the United States Air Force (USAF) as the winner in the KC-X tanker competition to replace older Boeing KC-135 Stratotankers. The first aircraft was delivered to the USAF in January 2019.

The USAF intends to procure 179 tankers by 2027. The Air Force indicated that the number of KC-46A aircraft to be procured had increased to 188 which is the absolute maximum number available under the original deal. The Air Force has also elected to pursue a "Tanker Production Extension Program" which will lead to a new contract with Boeing for up to 75 new KC-46A. The total airfare program would grow to 288 KC-46A if all options are exercised.