Airbus A330 MRTT 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.

In the U.S. Air Force (USAF), a boom operator is an aircrew member aboard tanker aircraft who is responsible for safely and effectively transferring aviation fuel from one military aircraft to another during flight (known as aerial refueling, air refueling, in-flight refueling, air-to-air refueling, and tanking). The name boom operator implies that one "operates a boom" (the flying boom), which is a long, extendable metal arm attached to the rear underside of the tanker that the boom operator connects to the fuel receptacle of a receiving aircraft (the receiver). The boom operator also controls the refueling drogue, a basket attached to a flexible hose that trails the tanker, when using the probe-and-drogue system. The USAF officially designates the boom operator career field as "In-Flight Refueling" with a specialty code of 1A0X1. However, this designation is usually reserved for administrative paperwork such as enlistment contracts and performance reports, as boom operators themselves are rarely referred to as in-flight refueling specialists within the USAF. The title "Boom Operator" is most commonly used, in reference to the aircrew position they occupy on the airplane, as noted in USAF regulations and aircraft flight manuals. Fellow crew members affectionately address them as "boom" or "boomer" (though the use of the term "boom" in this article refers to the flying boom, not the boom operator).

The boom operator crew position was created in 1948 when Boeing developed the flying boom at the request of the USAF. Prior to this, when the only practical means of transferring fuel was through a hose, other crew members fulfilled the duty of operating the air refueling equipment, such as the hose reel operator in the DH-4B and C-1 and the line operator in the B-24D and KB-29M using the grappled-line looped hose system. In the modern U.S. military, the boom operator crew position only exists in USAF tankers equipped with a flying boom, such as the KC-135, KC-10, and the newly developed KC-46. For tanker aircraft not equipped with a flying boom, such as the KC-130, HC-130, and F/A-18E/F, the specific crew member(s) responsible for operating the air refueling equipment and supervising refueling operations varies by aircraft. Boom-equipped tankers have been obtained by several foreign countries as a result of USAF tanker procurement programs and U.S. foreign military sales. An estimated 63 boom-equipped tankers (KC-135, KC-10, A330 MRTT, KC-767, and KC-33) are operated by 14 foreign countries; in comparison, the USAF operates 457 KC-135 and KC-10 tankers.