Boeing KC-135 Stratotanker in the context of "Tanker (aircraft)"

Aerial refueling (en-US), or aerial refuelling (en-GB), also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring aviation fuel from one aircraft (the tanker) to another (the receiver) while both aircraft are in flight. The two main refueling systems are probe-and-drogue, which is simpler to adapt to existing aircraft and the flying boom, which offers faster fuel transfer, but requires a dedicated boom operator station.

The procedure allows the receiving aircraft to remain airborne longer, extending its range or loiter time. A series of air refuelings can give range limited only by crew fatigue/physical needs and engineering factors such as engine oil consumption. Because the receiver aircraft is topped-off with extra fuel in the air, air refueling can allow a takeoff with a greater payload which could be weapons, cargo, or personnel: the maximum takeoff weight is maintained by carrying less fuel and topping up once airborne. Aerial refueling has also been considered as a means to reduce fuel consumption on long-distance flights greater than 3,000 nautical miles (5,600 km; 3,500 mi). Potential fuel savings in the range of 35–40% have been estimated for long-haul flights (including the fuel used during the tanker missions).

The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is an early long-range narrow-body jetliner designed and produced by the American Douglas Aircraft Company. Work began in 1952 toward the United States Air Force's (USAF) requirement for a jet-powered aerial refueling tanker. After losing the USAF's tanker competition to the rival Boeing KC-135 Stratotanker in May 1954, Douglas announced in June 1955 its derived jetliner project marketed to civil operators. In October 1955, Pan Am made the first order along with the competing Boeing 707, and many other airlines soon followed. The first DC-8 was rolled out in Long Beach Airport on April 9, 1958, and flew for the first time on May 30. Following Federal Aviation Administration (FAA) certification in August 1959, the DC-8 entered service with Delta Air Lines on September 18.

Permitting six-abreast seating, the four-engined, low-wing jet aircraft was initially produced in four 151 ft (46 m) long variants. The DC-8-10 was powered by Pratt & Whitney JT3C turbojets, and had a 273,000 lb (124 t) MTOW; the DC-8-20 had more powerful JT4A turbojets, for a 276,000 lb (125 t) MTOW. The intercontinental models had more fuel capacity, and had an MTOW of up to 315,000 lb (143 t); it was powered by JT4As for the Series 30, and by Rolls-Royce Conway turbofans for the Series 40. The Pratt & Whitney JT3D powered the later DC-8-50 and Super 60 (DC-8-61, -62, and -63) as well as freighter versions, and reached a MTOW of 325,000 lb (147 t). A stretched DC-8 variant was not initially considered, leading some airlines to order the competing Boeing 707 instead.

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.

The Boeing KC-97 Stratofreighter is a four-engined, piston-powered United States strategic tanker aircraft based on the Boeing C-97 Stratofreighter. It replaced the KB-29 and was succeeded by the Boeing KC-135 Stratotanker.

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.