View source for Aerial refueling

{{Use dmy dates|date=March 2023}}
{{short description|Procedure in which flying aircraft receive fuel from another aircraft}}
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{{more footnotes|date=March 2009}}
{{globalize|date=August 2017}}
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[[File:KC-135 refuels an F-16 Fighting Falcon.jpg|thumb|upright=1.35|A [[Boeing KC-135 Stratotanker|KC-135 Stratotanker]] refuels an [[F-16 Fighting Falcon]] using a flying boom]]

'''Aerial refueling''' ([[American English|en-us]]), or '''aerial refuelling''' ([[British English|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 [[List of tanker aircraft|tanker]]) to another (the receiver) while both aircraft are in flight.{{Efn|"AAR" can also stand for [[After Action Review]] (i.e. debriefing); "IFR" also stands for [[Instrument Flight Rules]].}} The two main refueling systems are ''[[#Probe-and-drogue|probe-and-drogue]]'', which is simpler to adapt to existing aircraft and the ''[[#Flying boom|flying boom]]'', which offers faster fuel transfer, but requires a dedicated [[Boom operator (military)|boom operator]] station.

The procedure allows the receiving aircraft to remain airborne longer, extending its range or [[Loiter (aeronautics)|loiter]] time. A series of air refuelings can give range limited only by crew [[Fatigue testing|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 (air and space craft)|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 {{convert|3000|nmi}}. Potential fuel savings in the range of 35–40% have been estimated for long-haul flights (including the fuel used during the tanker missions).<ref>{{cite journal|last=Nangia |first=R.K |title=Operations and aircraft design towards greener civil aviation using air-to-air refuelling |journal=The Aeronautical Journal |date=November 2006 |volume=Paper No. 3088. |issue=November |pages=705–721 |doi=10.1017/S0001924000001585 |s2cid=114942345 |url=http://www.greenerbydesign.org.uk/_FILES/publications/3088.pdf |access-date=20 October 2011 |url-status=dead |archive-url=https://web.archive.org/web/20131021064242/http://www.greenerbydesign.org.uk/_FILES/publications/3088.pdf |archive-date=21 October 2013 }}</ref>

Usually, the aircraft providing the fuel is specially designed for the task, although refueling pods may be fitted to existing aircraft designs in the case of "probe-and-drogue" systems.  The cost of the refueling equipment on both tanker and receiver aircraft and the specialized aircraft handling of the aircraft to be refueled (very close "line astern" formation flying) has resulted in the activity only being used in [[Military aviation|military operations]]; there are no regular civilian in-flight refueling activities. Originally trialed shortly before [[World War II]] on a limited scale to extend the range of British civilian [[Transatlantic flight|transatlantic]] [[flying boat]]s, and then employed after World War II on a large scale to extend the range of [[strategic bomber]]s, aerial refueling since the [[Vietnam War]] has been extensively used in large-scale military operations.

==Development history==

===Early experiments===
[[File:Refueling, 1923.jpg|thumb|right|[[Captain (land)|Capt.]] [[Lowell Smith]] and Lt. John P. Richter receiving the first mid-air refueling on 27 June 1923]]
Some of the earliest experiments in aerial refueling took place in the 1920s; two slow-flying aircraft flew in formation, with a hose run down from a hand-held fuel tank on one aircraft and placed into the usual fuel filler of the other. The first mid-air refueling, based on the development of [[Alexander P. de Seversky]], between two planes occurred on 25 June 1923, between two [[Airco DH-4B]] [[biplane]]s of the [[United States Army Air Service]]. An endurance record was set by three DH-4Bs (a receiver and two tankers) on 27–28 August 1923, in which the receiver airplane remained aloft for more than 37 hours using nine mid-air refueling to transfer {{convert|687|usgal|L}} of [[aviation gasoline]] and {{convert|38|usgal|L}} of engine oil. The same crews demonstrated the utility of the technique on 25 October 1923, when a DH-4 flew from [[Sumas, Washington]], on the [[Canada–United States border]], to [[Tijuana, Mexico]], landing in [[San Diego]], using mid-air refuelings at [[Eugene, Oregon]], and [[Sacramento, California]].

Similar trial demonstrations of mid-air refueling technique took place at the [[Royal Aircraft Establishment]] in [[England]] and by the [[Armée de l'Air]] in [[France]] in the same year, but these early experiments were not yet regarded as a practical proposition, and were generally dismissed as stunts.

As the 1920s progressed, greater numbers of aviation enthusiasts vied to set new aerial long-distance records, using inflight air refueling. One such enthusiast, who would revolutionize aerial refueling was Sir [[Alan Cobham]], member of the [[Royal Flying Corps]] in [[World War I]], and a pioneer of long-distance aviation. During the 1920s, he made long-distance flights to places as far afield as [[Africa]] and [[Australia]] and he began experimenting with the possibilities of in-flight refueling to extend the range of flight.<ref>Colin Cruddas, ''Highways to the Empire'' (Air Britain, 2006, {{ISBN|0-85130-376-5}}); G.H. Pirie, ''Air Empire: British Imperial Civil Aviation, 1919–39'' (Manchester University Press, 2009), Chapter 6. {{ISBN|978-0-7190-4111-2}}; G.H. Pirie, ''Cultures and Caricatures of British imperial Aviation: Passengers, Pilots, Publicity'' (Manchester University Press, 2012), Chapter 4.</ref>

Cobham was one of the founding directors of [[Airspeed Ltd.|Airspeed Limited]], an aircraft manufacturing company that went on to produce a specially adapted [[Airspeed Courier]] that Cobham used for his early experiments with in-flight refueling. This craft was eventually modified by Airspeed to Cobham's specification, for a non-stop flight from [[London]] to [[India]], using in-flight refueling to extend the plane's flight duration.

Meanwhile, in 1929, a group of [[United States Army Air Corps|US Army Air Corps]] fliers, led by then Major [[Carl Andrew Spaatz|Carl Spaatz]], set an endurance record of over 150 hours with a Fokker C-2A named the [[Question Mark (airplane)|''Question Mark'']] over Los Angeles. Between 11 June and 4 July 1930, the brothers John, Kenneth, Albert, and Walter Hunter set a new record of 553 hours 40 minutes over [[Chicago]] using two [[Stinson Detroiter|Stinson SM-1 Detroiters]] as refueler and receiver. Aerial refueling remained a very dangerous process until 1935, when brothers [[The Flying Keys|Fred and Al Key]] demonstrated a spill-free refueling nozzle, designed by A. D. Hunter.<ref>There is no evidence of a relationship between A.D. Hunter and the Hunter brothers.</ref> They exceeded the Hunters' record by nearly 100 hours in a [[Curtiss Robin]] monoplane,<ref> {{cite web|url= http://www.nasm.si.edu/imagedetail.cfm?imageID=1150|title= 
National Air and Space Museum image|archive-url = https://web.archive.org/web/20090416144548/http://www.nasm.si.edu/imagedetail.cfm?imageID=1150|archive-date= April 16, 2009}}</ref> staying aloft for more than 27 days.<ref name="HistAv19">History of Aviation, Part 19, 1938</ref>

The US was mainly concerned about transatlantic flights for faster postal service between Europe and America. In 1931 W. Irving Glover, the second assistant postmaster, wrote an extensive article for ''Popular Mechanics'' concerning the challenges and the need for such a regular service. In his article he even mentioned the use of aerial refueling after takeoff as a possible solution.<ref>{{cite magazine|magazine=Popular Mechanics|author=Hearst Magazines|title=Wings Across The Atlantic|url=https://books.google.com/books?id=u-IDAAAAMBAJ&pg=PA186|date=February 1931|publisher=Hearst Magazines|page=190|access-date=4 June 2016|archive-date=13 March 2023|archive-url=https://web.archive.org/web/20230313153158/https://books.google.com/books?id=u-IDAAAAMBAJ&pg=PA186|url-status=live}}</ref>

At [[Le Bourget Airport]] near Paris, the [[Aéro-Club de France]] and the 34th Aviation Regiment of the [[French Air Force]] were able to demonstrate passing fuel between machines at the annual aviation fete at [[Vincennes]] in 1928.<ref>Flight Magazine archive, 10 January 1929</ref> The UK's [[Royal Aircraft Establishment]] was also running mid-air refueling trials, with the aim to use this technique to extend the range of the long-distance [[flying boats]] that serviced the [[British Empire]]. By 1931 they had demonstrated refueling between two [[Vickers Virginia]]s, with fuel flow controlled by an automatic valve on the hose which would cut off if contact was lost.<ref>Flight Magazine archive, 3 July 1931, p.&nbsp;623</ref>

[[Royal Air Force]] [[officer]] [[Richard Atcherley]] had observed the dangerous aerial-refueling techniques in use at [[barnstorming]] events in the US and determined to create a workable system.<ref>{{cite web|author=Richard K. Smith|title=Seventy Five Years of Inflight Refueling|url=http://media.defense.gov/2010/Sep/29/2001329785/-1/-1/0/AFD-100929-015.pdf|access-date=1 October 2013|archive-date=24 August 2017|archive-url=https://web.archive.org/web/20170824052135/https://media.defense.gov/2010/Sep/29/2001329785/-1/-1/0/AFD-100929-015.pdf|url-status=dead}}</ref> While posted to the [[Middle East]] he developed and patented his 'crossover' system in 1934, in which the tanker trailed a large hooked line that would reel in a similar dropped line from the receiver, allowing the refueling to commence. In 1935, Cobham sold off the airline Cobham Air Routes Ltd to [[Morton Air Services#Olley Air Service|Olley Air Service]] and turned to the development of inflight refueling, founding the company [[Flight Refuelling Ltd]]. Atcherly's system was bought up by Cobham's company, and with some refinement and continuous improvement through the late '30s, it became the first practical refueling system.<ref>{{Cite web|url=http://www.gaflight.org/midair%20refueling%20p1.htm|title=Mid-air refuelling in Gander|access-date=4 October 2013|archive-date=24 March 2017|archive-url=https://web.archive.org/web/20170324143411/http://www.gaflight.org/midair%20refueling%20p1.htm|url-status=live}}</ref>

====Grappled-line looped-hose====
[[File:'Lucky Lady II" being refuelled by B-29M 45-21708 061215-F-1234S-002.jpg|thumb|right|The US Air Force [[Boeing B-50 Superfortress]] ''[[Lucky Lady II]]'' being refueled by grappled-line looped-hose during the first non-stop circumnavigation of the world by air (1949)]]
Sir [[Alan Cobham]]'s ''grappled-line looped-hose'' air-to-air refueling system borrowed from techniques patented by David Nicolson and John Lord, and was publicly demonstrated for the first time in 1935. In the system the receiver aircraft, at one time an [[Airspeed Courier]], trailed a steel cable which was then grappled by a line shot from the tanker, a [[Handley Page Type W#W10|Handley Page Type W10]]. The line was then drawn back into the tanker where the receiver's cable was connected to the refueling hose. The receiver could then haul back in its cable bringing the hose to it. Once the hose was connected, the tanker climbed sufficiently above the receiver aircraft to allow the fuel to flow under gravity.<ref>{{cite magazine|magazine=Popular Science|author=Bonnier Corporation|title=Gas Station In The Sky|url=https://books.google.com/books?id=KSYDAAAAMBAJ&pg=RA2-PA82|date=January 1947|publisher=Bonnier Corporation|page=2}}</ref><ref>[http://www.flightglobal.com/pdfarchive/view/1945/1945%20-%202295.html?search=Flight%20Refuelling '' "Refuelling In Flight" '', Flight Magazine, November 22, 1945] {{Webarchive|url=https://web.archive.org/web/20131005123217/http://www.flightglobal.com/pdfarchive/view/1945/1945%20-%202295.html?search=Flight%20Refuelling |date=5 October 2013 }} close-up drawing of receiver pawl grapnel and tanker haul line projectile</ref>

When Cobham was developing his system, he saw the need as purely for long-range transoceanic commercial aircraft flights,<ref>{{cite web|url=http://www.flightglobal.com/pdfarchive/view/1947/1947%20-%200392.html|title=flight march – receiver aircraft – advertisements flight – 1947 – 0392 – Flight Archive|access-date=19 November 2016|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402160634/http://www.flightglobal.com/pdfarchive/view/1947/1947%20-%200392.html|url-status=live}}</ref> but modern aerial refueling is used exclusively by military aircraft.

In 1934, Cobham had founded [[Flight Refuelling Ltd]] (FRL) and by 1938 had used its ''looped-hose'' system to refuel aircraft as large as the [[Short Empire]] flying boat ''Cambria'' from an [[Armstrong Whitworth AW.23]].<ref name="HistAv19"/> [[Handley Page H.P.54 Harrow|Handley Page Harrows]] were used in the 1939 trials to perform aerial refueling of the Empire flying boats for regular transatlantic crossings. From 5 August to 1 October 1939, sixteen crossings of the Atlantic were made by Empire flying boats, with fifteen crossings using FRL's aerial refueling system.<ref>Note&nbsp;– on one flight there was a high westerly wind and no need for aerial refueling</ref> After the sixteen crossings further trials were suspended due to the outbreak of World War II.<ref>{{cite web|url=http://www.flightglobal.com/pdfarchive/view/1940/1940%20-%201219.html?search=Flight%20Refuelling|title=imperial airways – 1940 – 1219 – Flight Archive|access-date=19 November 2016|archive-date=5 October 2013|archive-url=https://web.archive.org/web/20131005122815/http://www.flightglobal.com/pdfarchive/view/1940/1940%20-%201219.html?search=Flight%20Refuelling|url-status=live}}</ref>

During the closing months of World War II, it had been intended that [[Tiger Force (air)|Tiger Force]]'s [[Avro Lancaster|Lancaster]] and [[Avro Lincoln|Lincoln]] bombers would be in-flight refueled by converted [[Handley Page Halifax|Halifax]] tanker aircraft, fitted with the FRL's looped-hose units, in operations against the [[Japan|Japanese homelands]], but the war ended before the aircraft could be deployed. After the war ended, the USAF bought a small number of FRL looped-hose units and fitted a number of B-29s as tankers to refuel specially equipped B-29s and later B-50s. The USAF made only one major change in the system used by the RAF. The USAF version had auto-coupling of the refueling nozzle, where the leader line with the refueling hose is pulled to the receiver aircraft and a refueling receptacle on the belly of the aircraft, allowing high-altitude air-to-air refueling and doing away with the aircraft having to fly to a lower altitude to be depressurized so a crew member could manually do the coupling.<ref>{{cite magazine|magazine=Popular Science|author=Bonnier Corporation|title=What Can Our Bombers Do Now?|url=https://books.google.com/books?id=QCgDAAAAMBAJ&pg=PA79|date=August 1948|publisher=Bonnier Corporation|page=79|access-date=4 June 2016|archive-date=13 March 2023|archive-url=https://web.archive.org/web/20230313153145/https://books.google.com/books?id=QCgDAAAAMBAJ&pg=PA79|url-status=live}}</ref>

This air-to-air refueling system was used by the [[B-50 Superfortress]] ''[[Lucky Lady II]]'' of the 43rd Bomb Wing to make its famous first non-stop around-the-world flight in 1949.<ref>{{cite web|url=http://www.flightglobal.com/pdfarchive/view/1949/1949%20-%200461.html|title=flight – lucky lady – flight refuelling – 1949 – 0461 – Flight Archive|access-date=19 November 2016|archive-date=21 August 2016|archive-url=https://web.archive.org/web/20160821144517/https://www.flightglobal.com/pdfarchive/view/1949/1949%20-%200461.html|url-status=live}}</ref><ref>'' "B-50s In Great Britain" '', Flight magazine, 1 September 1949</ref> From 26 February to 3 March 1949, ''Lucky Lady II'' flew non-stop around the world in 94&nbsp;hours and 1&nbsp;minute, a feat made possible by four aerial refuelings from four pairs of [[Boeing KB-29|KB-29M]] tankers of the 43d ARS. Before the mission, crews of the 43rd had experienced only a single operational air refueling contact. The flight started and ended at [[Carswell Air Force Base]] in [[Fort Worth, Texas]] with the refuelings accomplished over [[the Azores]], [[Saudi Arabia]], the Pacific Ocean near [[Guam]], and between [[Hawaii]] and the [[West Coast of the United States|West Coast]].<ref>{{Cite journal|last=Hallex|first=Steve|title=Around the World in 94 Hours*|journal=Logbook|volume= 14| issue =  1, 1st Quarter 2016}}</ref>

====Probe-and-drogue system====
Cobham's company FRL (now part of [[Cobham plc]]) soon realized that their looped-hose system left much to be desired and began work on an improved system that is now commonly called the ''probe-and-drogue'' air-to-air refueling system and today is one of the two systems chosen by air forces for air-to-air refueling, the other being the flying-boom system. In post-war trials the RAF used a modified Lancaster tanker employing the much improved probe-and-drogue system, with a modified [[Gloster Meteor|Gloster Meteor F.3]] jet fighter, [[United Kingdom military aircraft serials|serial]] ''EE397'', fitted with a nose-mounted probe.<ref>{{cite web|url=http://www.cobham75.com/cobham-the-company-1934-1985/air-to-air-refuelling-takes-off.aspx |title=Cobham 75 :: Air-to-Air Refuelling Takes off |access-date=17 November 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110708171825/http://www.cobham75.com/cobham-the-company-1934-1985/air-to-air-refuelling-takes-off.aspx |archive-date=8 July 2011 }}</ref><ref>{{cite magazine|magazine=Popular Science|author=Bonnier Corporation|title=Jet Refuels Like Humming Bird|url=https://books.google.com/books?id=giQDAAAAMBAJ&pg=PA131|date=October 1949|publisher=Bonnier Corporation|page=131|access-date=16 May 2019|archive-date=13 March 2023|archive-url=https://web.archive.org/web/20230313153158/https://books.google.com/books?id=giQDAAAAMBAJ&pg=PA131|url-status=live}}</ref> On 7 August 1949, the Meteor flown by FRL [[test pilot]] Pat Hornidge took off from [[RAF Tarrant Rushton|Tarrant Rushton]] and remained airborne for 12 hours and 3 minutes, receiving {{convert|2352|impgal|L}} of fuel in ten refuelings from a Lancaster tanker. Hornidge flew an overall distance of {{convert|3600|mi|km|abbr=on}}, achieving a new jet endurance record.<ref>{{citation |journal=Flight |year=1949 |url=http://www.flightglobal.com/pdfarchive/view/1949/1949%20-%201413.html |title=Meteor's 12-hour Flight |access-date=13 April 2014 |archive-date=8 July 2017 |archive-url=https://web.archive.org/web/20170708222447/https://www.flightglobal.com/pdfarchive/view/1949/1949%20-%201413.html |url-status=live }}</ref><ref>{{cite web|url=http://www.the-best-of-british.com/PlaneCrazyHeritage/airpictorial/1999/RefuellingFDC.htm|title=50 Years of Probe and Drogue Flight Refuelling cover signed Air Chief Marshal Sir Michael Knight KCB AFC FRAES|access-date=19 November 2016|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304114228/http://www.the-best-of-british.com/PlaneCrazyHeritage/airpictorial/1999/RefuellingFDC.htm|url-status=live}}</ref>

Modern specialized [[Tanker (aircraft)|tanker]] aircraft have equipment specially designed for the task of offloading fuel to the receiver aircraft, based on drogue and probe, even at the higher speeds modern [[jet aircraft]] typically need to remain airborne.

In January 1948, General Carl Spaatz, then the first [[Chief of Staff of the United States Air Force|Chief of Staff]] of the new [[United States Air Force]], made aerial refueling a top priority of the service.  In March 1948, the USAF purchased two sets of FRL's looped-hose in-flight refueling equipment, which had been in practical use with [[British Overseas Airways Corporation]] (BOAC) since 1946, and manufacturing rights to the system. FRL also provided a year of technical assistance. The sets were immediately installed in two [[Boeing B-29 Superfortress]]es, with plans to equip 80 B-29s.

Flight testing began in May 1948 at [[Wright-Patterson Air Force Base]], [[Ohio]], and was so successful that in June orders went out to equip all new B-50s and subsequent bombers with receiving equipment. Two dedicated air refueling units were formed on 30 June 1948: the [[43d Air Refueling Squadron]] at [[Davis-Monthan Air Force Base]], [[Arizona]], and the [[509th Weapons Squadron|509th Air Refueling Squadron]] at [[Walker Air Force Base]], [[New Mexico]]. The first ARS aircraft used FRL's looped-hose refueling system, but testing with a boom system followed quickly in the autumn of 1948.

The first use of aerial refueling in combat took place during the Korean War, involving F-84 fighter-bombers flying missions from Japanese airfields, due to Chinese-North Korean forces overrunning many of the bases for jet aircraft in South Korea, refueling from converted B-29s using the drogue-and-probe in-flight refueling system with the probe located in one of the F-84's wing-tip fuel tanks.

==Systems==
{{More citations needed section|date=April 2012}}

===Flying boom===
[[File:Eindhoven Air Base (8613167434).jpg|thumb|right|Dutch Air Force [[McDonnell Douglas KC-10 Extender|KDC-10]] refueling boom]]
The flying boom is a rigid, telescoping tube with movable [[flight control surfaces]] that a [[boom operator (US military)|boom operator]] on the tanker aircraft extends and inserts into a receptacle on the receiving aircraft. All boom-equipped tankers (e.g. [[KC-135 Stratotanker]], [[KC-10 Extender]], [[KC-46 Pegasus]]) have a single boom and can refuel one aircraft at a time with this mechanism.

====History====
In the late 1940s, General [[Curtis LeMay]], commander of the [[Strategic Air Command]] (SAC), asked [[Boeing]] to develop a refueling system that could transfer fuel at a higher rate than had been possible with earlier systems using flexible hoses, resulting in the flying boom system.  The B-29 was the first to employ the boom, and between 1950 and 1951, 116 original B-29s, designated KB-29Ps, were converted at the Boeing plant at [[Renton, Washington]]. Boeing went on to develop the world's first production aerial tanker, the [[KC-97 Stratofreighter]], a piston-engined [[Boeing 377|Boeing Stratocruiser]] (USAF designation [[C-97 Stratofreighter]]) with a Boeing-developed flying boom and extra kerosene (jet fuel) tanks feeding the boom. The Stratocruiser airliner itself was developed from the B-29 bomber after [[World War II]]. In the KC-97, the mixed gasoline/kerosene fuel system was clearly not desirable and it was obvious that a jet-powered tanker aircraft would be the next development, having a single type of fuel for both its own engines and for passing to receiver aircraft. The 230&nbsp;mph (370&nbsp;km/h) cruise speed of the slower, piston-engined KC-97 was also a serious issue, as using it as an aerial tanker forced the newer jet-powered military aircraft to slow down to mate with the tanker's boom, a highly serious issue with the newer supersonic aircraft coming into service at that time, which could force such receiving aircraft in some situations to slow down enough to approach their [[stall speed]] during the approach to the tanker. It was no surprise that, after the KC-97, Boeing began receiving contracts from the USAF to build jet tankers based on the [[Boeing 367-80]] (Dash-80) airframe. The result was the [[Boeing KC-135 Stratotanker]], of which 732 were built.

The flying boom is attached to the rear of the tanker aircraft. The attachment is [[gimbal]]led, allowing the boom to move with the receiver aircraft. The boom contains a rigid pipe to transfer fuel. The fuel pipe ends in a nozzle with a flexible ball joint. The nozzle mates to the "receptacle" in the receiver aircraft during fuel transfer. A [[poppet valve]] in the end of the nozzle prevents fuel from exiting the tube until the nozzle properly mates with the receiver's refueling receptacle. Once properly mated, [[Toggle mechanism|toggles]] in the receptacle engage the nozzle, holding it locked during fuel transfer.

The "flying" boom is so named because [[flight control surfaces]], small movable [[airfoils]] that are often in a [[V-tail]] configuration, are used to move the boom by creating aerodynamic forces. They are actuated [[hydraulics|hydraulically]] and controlled by the [[boom operator (US military)|boom operator]] using a control stick. The boom operator also telescopes the boom to make the connection with the receiver's receptacle.

To complete an aerial refueling, the tanker and receiver aircraft rendezvous, flying in formation. The receiver moves to a position behind the tanker, within safe limits of travel for the boom, aided by director lights or directions radioed by the boom operator. Once in position, the operator extends the boom to make contact with the receiver aircraft. Once in contact, fuel is pumped through the boom into the receiver aircraft.
[[File:KC-135Boom-operator-521.jpg|thumb|[[USAF]] [[KC-135]] [[Boom operator (military)|boom operator]] view from the boom pod.]]
While in contact, the receiver pilot must continue to fly within the "air refueling envelope", the area in which contact with the boom is safe. Moving outside of this envelope can damage the boom or lead to mid-air collision, for example the [[1966 Palomares B-52 crash]]. If the receiving aircraft approaches the outer limits of the envelope, the boom operator will command the receiver pilot to correct their position and disconnect the boom if necessary.

When the desired amount of fuel has been transferred, the two aircraft disconnect and the receiver aircraft departs the formation. When not in use, the boom is stored flush with the bottom of the tanker's fuselage to minimize drag.

In the KC-97 and KC-135 the boom operator lies prone, while the operator is seated in the [[KC-10]], all viewing operations through a window at the tail. The [[KC-46]] seats two operators at the front of the aircraft viewing camera video on 3D screens.

The US Air Force fixed-wing aircraft use the flying boom system, along with Australia (KC-30A),<ref>{{cite web |title=KC-30A MRTT |url=https://www.airforce.gov.au/aircraft/kc-30a-mrtt |website=airforce.gov.au |access-date=30 August 2024}}</ref> the Netherlands (KDC-10), Israel (modified Boeing 707), Japan (KC-767), Turkey (KC-135Rs), and Iran (Boeing 707 and 747). The system allows higher fuel flow rates (up to {{convert|1000|USgal|L}} / {{convert|6500|lb|kg}} per minute for the KC-135, but does require a boom operator, and can only refuel one aircraft at a time.

===Probe-and-drogue===
[[File:Fuel Prices Rise Again MOD 45146995.jpg|thumb|right|Using a probe-and-drogue, a Royal Air Force [[Lockheed C-130 Hercules|C-130K Hercules]] crew practice refuelling from an RAF [[Vickers VC10|VC10]] tanker over the Falkland Islands, 2005]]{{No sources|section|date=January 2025}}
The probe-and-drogue refueling method employs a flexible hose that trails from the tanker aircraft. The ''drogue'' (or ''para-drogue''), sometimes called a ''basket'', is a fitting resembling a [[shuttlecock]], attached at its narrow end (like the "cork" nose of a shuttlecock) with a valve to a flexible hose. The drogue stabilizes the hose in flight and provides a funnel to aid insertion of the receiver aircraft probe into the hose. The hose connects to a hose drum unit (HDU). When not in use, the hose/drogue is reeled completely into the HDU.

The receiver has a ''probe'', which is a rigid, protruding or pivoted retractable arm placed on the aircraft's nose or fuselage to make the connection. Most modern versions of the probe are usually designed to be retractable, and are retracted when not in use, particularly on high-speed aircraft.{{citation needed|date=January 2016}}

At the end of the probe is a valve that is closed until it mates with the drogue's forward internal receptacle, after which it opens and allows fuel to pass from tanker to receiver. The valves in the probe and drogue that are most commonly used are to a [[NATO]] standard and were originally developed by the company [[Cobham plc|Flight Refuelling Limited]] in the UK and deployed in the late 1940s and 1950s.{{citation needed|date=January 2016}} This standardization enables drogue-equipped tanker aircraft from many nations to refuel probe-equipped aircraft from other nations.

The NATO-standard probe system incorporates shear rivets that attach the refueling valve to the end of the probe.{{citation needed|date=January 2016}} This is so that if a large side or vertical load develops while in contact with the drogue, the rivets shear and the fuel valve breaks off, rather than the probe or receiver aircraft suffering structural damage. A so-called "broken probe" (actually a broken fuel valve, as described above) may happen if poor flying technique is used by the receiver pilot, or in turbulence. Sometimes the valve is retained in the tanker drogue and prevents further refueling from that drogue until removed during ground maintenance.

==== Buddy store ====
[[File:FA-18E of VFA-81 refuels Rafale of Flottille 11F in March 2015.JPG|thumb|An [[Boeing F/A-18E/F Super Hornet|F/A-18E Super Hornet]] of the [[United States Navy|US Navy]] acts as a buddy tanker for a [[Dassault Rafale|Rafale]] of the [[French Navy]] over the [[Arabian Sea]], 2015]] 
A "buddy store" or "buddy pod" is an external pod loaded on an aircraft [[hardpoint]] that contains a hose and drogue system (HDU).<ref name="ReferenceA">{{cite book |author=Naval Air Systems Command |title=A1-F18AC-NFM-000 Naval Aviation Training and Operating Procedures Standardization (NATOPS) Manual |publisher=United States [[United States Department of the Navy|Department of the Navy]] |date=1 August 2006 |page=364}}</ref> Buddy stores allow fighter{{\}}bomber aircraft to be reconfigured for "buddy tanking" other aircraft. This allows an air combat force without dedicated/specialized tanker support (for instance, a [[carrier air wing]]) to extend the range of its strike aircraft. In other cases, using the buddy store method allows a [[Aircraft carrier|carrier]]-based aircraft to take-off with a heavier than usual load less fuel than might be necessary for its tasking. The aircraft would then topped-up with fuel from an HDU-equipped "buddy" tanker, a method previously used by the [[Royal Navy]] in operating its [[Supermarine Scimitar]], [[de Havilland Sea Vixen]], and [[Blackburn Buccaneer]]s; in the Buccaneer's case using a bomb-bay-mounted tank and HDU.

[[File:US Navy 110610-N-KA046-002 Two MH-53E Super Stallion helicopters assigned to Marine Medium Tiltrotor Squadron (VMM) 263 (Reinforced), 22nd Marine E (cropped).jpg|thumb|right|A [[United States Marine Corps|USMC]] [[Lockheed Martin KC-130|KC-130 Hercules]] refuels a pair of USMC [[Sikorsky CH-53E Super Stallion|CH-53E Super Stallion]]s, 2011 ]]
The tanker aircraft flies straight and level and extends the hose/drogue, which is allowed to trail out behind and below the tanker under normal aerodynamic forces. The pilot of the receiver aircraft extends the probe (if required) and uses normal flight controls to "fly" the refueling probe directly into the basket. This requires a closure rate of about two knots (walking speed) to push the hose several feet into the HDU and solidly couple the probe and drogue. Too little closure will cause an incomplete connection and no fuel flow (or occasionally leaking fuel). Too much closure is dangerous because it can trigger a strong transverse [[oscillation]] in the hose, severing the probe tip.

The optimal approach is from behind and below (not level with) the drogue. Because the drogue is relatively light (typically soft canvas webbing) and subject to aerodynamic forces, it can be pushed around by the bow wave of approaching aircraft, exacerbating engagement even in smooth air. After initial contact, the hose and drogue is pushed forward by the receiver a certain distance (typically, a few feet), and the hose is reeled slowly back onto its drum in the HDU. This opens the tanker's main refueling valve allowing fuel to flow to the drogue under the appropriate pressure (assuming the tanker crew has energized the pump). Tension on the hose is aerodynamically 'balanced' by a motor in the HDU so that as the receiver aircraft moves fore and aft, the hose retracts and extends, thus preventing bends in the hose that would cause undue side loads on the probe.  Fuel flow is typically indicated by illumination of a green light near the HDU. If the hose is pushed in too far or not far enough, a cutoff switch will inhibit fuel flow, which is typically accompanied by an amber light.  Disengagement is commanded by the tanker pilot with a red light.<ref name="ReferenceA" />

The [[List of United States naval aircraft|US Navy]], [[United States Marine Corps Aviation|Marine Corps]], and some [[List of equipment of the United States Army#Aircraft|Army]] aircraft refuel using the "hose-and-drogue" system, as do most aircraft flown by western European militaries. The [[Soviet Union]] also used a hose-and-drogue system, dubbed UPAZ,<ref>{{cite web |url=http://www.zvezda-npp.ru/english/06.htm |title=Inflight Refueling |work=Zvezda JSC |archive-url=https://web.archive.org/web/20070816232906/http://www.zvezda-npp.ru/english/06.htm |archive-date=16 August 2007 |access-date=6 July 2021}}</ref> and thus later Russian aircraft may be equipped with probe and drogue. The Chinese PLAF has a fleet of [[Xian H-6]] bombers modified for aerial refueling, and plans to add Russian [[Ilyushin Il-78]] aerial refueling tankers.{{sfn|Cordesman|Kleiber|2007|page=158}}
Tankers can be equipped with multipoint hose-and-drogue systems, allowing them to refuel two (or more) aircraft simultaneously, reducing time spent refueling by as much as 75% for a four-aircraft strike package.<ref>Maj. [[Marck R. Cobb]], "Aerial Refueling: The Need for a Multipoint, Dual-System Capability," AU-ARI-CP-87-3, Air University Press, July 1987.</ref>

===Boom drogue adapter units===
[[File:20200311 KC-135 Stratotanker Tail 62-3565-Kadena AB-41.jpg|thumb|A US Air Force KC-135 with a drogue adapter attached to its boom|alt=Large, 4-engine aircraft in flight with components for aerial refueling]]{{No sources|section|date=January 2025}}
USAF KC-135 and [[French Air Force]] KC-135FR refueling-boom equipped tankers can be field-converted to a probe-and-drogue system using a special adapter unit. In this configuration, the tanker retains its articulated boom, but has a hose/drogue at the end of it instead of the usual nozzle. The tanker boom operator holds the boom still while the receiver aircraft flies the probe into the basket. Unlike the soft canvas basket used in most drogue systems, the adapter units use a steel basket, grimly known as the "iron maiden" by [[naval aviator]]s because of its unforgiving nature. Soft drogues can be contacted slightly off center, wherein the probe is guided into the hose receptacle by the canvas drogue. The metal drogue, when contacted even slightly off center, will pivot out of place, potentially "slapping" the aircraft's fuselage and causing damage.{{Dubious|date=January 2025}}

The other major difference with this system is that when contacted, the hose does not "retract" into an HDU. Instead, the hose bends depending on how far it is pushed toward the boom. If it is pushed too far, it can loop around the probe or nose of the aircraft, damage the windscreen, or cause contact with the rigid boom. If not pushed far enough, the probe will disengage, halting fueling. Because of a much smaller position-keeping tolerance, staying properly connected to a KC-135 adapter unit is considerably more difficult than staying in a traditional hose/drogue configuration. When fueling is complete, the receiver carefully backs off until the probe refueling valve disconnects from the valve in the basket. Off center disengagements, like engagements, can cause the drogue to "prang" the probe and/or strike the aircraft's fuselage.

===Multiple systems===
[[File:KC-10 Extender with the 76th Air Refueling Squadron.jpg|thumb|A KC-10 Extender]]
Some tankers have both a boom and one or more complete hose-and-drogue systems. The USAF [[KC-10]] has both a flying boom and a separate hose-and-drogue system manufactured by [[Cobham (company)|Cobham]]. Both are on the aircraft centerline at the tail of the aircraft, so only one can be used at once. However, such a system allows all types of probe- and receptacle-equipped aircraft to be refueled in a single mission, without landing to install an adapter. Other tankers are equipped with hose-and-drogue attachments that do not interfere with the operation of the centerline boom: many [[Boeing KC-135 Stratotanker|KC-135s]] are equipped with dual under-wing attachments known as [[Boeing KC-135 Stratotanker#Further upgrades and derivatives|Multi-point Refueling System]] (MPRSs), while some KC-10s and [[Airbus A330 MRTT|A330 MRTTs]] have similar under-wing refueling pods (referred to as Wing Air Refueling Pods or WARPs on the KC-10).

===Wing-to-wing===
A small number of Soviet [[Tu-4|Tu-4s]] and [[Tu-16]]s (the tanker variant was Tu-16Z), used a wing-to-wing method. Similar to the probe-and-drogue method but more complicated, the tanker aircraft released a flexible hose from its wingtip. An aircraft flying alongside had to catch the hose with a special lock under its wingtip. After the hose was locked and the connection was established, the fuel was pumped.<ref>note&nbsp;– even today there is much confusion about how this system actually worked</ref>

===Simple grappling===
Some historic systems used for pioneering aerial refueling used the grappling method, where the tanker aircraft unreeled the fuel hose and the receiver aircraft would grapple the hose midair, reel it in and connect it so that fuel can be transferred either with the assistance of pumps or simply by [[siphon|gravity feed]]. This was the method used on the [[Question Mark (airplane)|Question Mark]] endurance flight in 1929.

==Compatibility issues==
The probe-and-drogue system is not compatible with flying boom equipment, creating a problem for military planners where mixed forces are involved.<ref name="autogenerated1">{{Cite journal|last1=Christopher|first1=Bolkcom|last2=D.|first2=Klaus, Jon|date=11 May 2005|title=Air Force Aerial Refueling Methods: Flying Boom versus Hose-and-Drogue|url=https://digital.library.unt.edu/govdocs/crs/permalink/meta-crs-6702:1|journal=Digital Library|language=en|access-date=27 October 2017|archive-date=11 May 2009|archive-url=https://web.archive.org/web/20090511192223/http://digital.library.unt.edu/govdocs/crs/permalink/meta-crs-6702%3A1|url-status=live}}</ref> Incompatibility can also complicate the procurement of new systems. The Royal Canadian Air Force currently wish to purchase the [[Lockheed Martin F-35 Lightning II#F-35A|F-35A]], which can only refuel via the flying boom, but only possess [[CC-150|probe-and-drogue refuelers]]. The potential cost of converting F-35As to probe-and-drogue refueling (as is used on US Navy & Marine Corps [[Lockheed Martin F-35 Lightning II#F-35B|F-35B]]s and [[Lockheed Martin F-35 Lightning II#F-35C|F-35C]]s) added to the early-2010s political controversy which surrounded F-35 procurement within the RCAF.<ref>{{cite web |url=http://www.macleans.ca/general/canadian-military-unable-to-refuel-new-jets-in-mid-air/ |title=Canadian military unable to refuel new jets in mid-air |author=<!--Staff writer(s); no by-line.--> |date=31 January 2011 |website=Macleans.ca |access-date=13 June 2015 |archive-date=14 June 2015 |archive-url=https://web.archive.org/web/20150614173144/http://www.macleans.ca/general/canadian-military-unable-to-refuel-new-jets-in-mid-air/ |url-status=live }}</ref>{{update after|2022|7|18}}<!-- how was the controversy resolved in Canada? -->

These concerns can be addressed by drogue adapters (see section "Boom drogue adapter units" above) that allow drogue aircraft to refuel from boom-equipped aircraft, and by refuelers that are equipped with both drogue and boom units and can thus refuel both types in the same flight, such as the KC-10, MPRS KC-135, or Airbus A330 MRTT.

===Strategic===
[[File:A KC-135 Stratotanker from the 127th Air Refueling Group performs a night time refueling for a C-17 Globemaster III.jpg|
thumb|right|A [[C-17 Globemaster III]] receives fuel from a KC-135 during night operations.]]
The development of the [[Boeing KC-97 Stratofreighter|KC-97]] and [[Boeing KC-135 Stratotanker]]s was pushed by the [[Cold War]] requirement of the United States to be able to keep fleets of [[nuclear bomb|nuclear]]-armed [[B-47 Stratojet]] and [[B-52 Stratofortress]] [[strategic bombers]] airborne around-the-clock either to threaten retaliation against a [[Soviet Union|Soviet]] strike for [[mutual assured destruction]], or to bomb the USSR first had it been ordered to do so. The bombers would fly orbits around their assigned positions from which they were to enter Soviet airspace if they received the order, and the tankers would refill the bombers' fuel tanks so that they could keep a force in the air 24 hours a day, and still have enough fuel to reach their targets in the Soviet Union. This also ensured that a [[Pre-emptive nuclear strike|first strike]] against the bombers' airfields could not obliterate the US's ability to retaliate by bomber.

In 1958, Valiant tankers in the UK were developed with one HDU mounted in the bomb-bay. Valiant tankers of 214 Squadron were used to demonstrate radius of action by refueling a Valiant bomber non-stop from UK to Singapore in 1960 and a Vulcan bomber to Australia in 1961. Other UK exercises involving refueling aircraft from Valiant tankers included [[Gloster Javelin|Javelin]] and [[English Electric Lightning|Lightning]] fighters, also Vulcan and Victor bombers. For instance, in 1962 a squadron of Javelin air defense aircraft was refueled in stages from the UK to [[India]] and back (exercise "Shiksha"). After the retirement of the Valiant in 1965, the Handley Page Victor took over the UK refueling role and had three hoses (HDUs). These were a fuselage-mounted HDU and a refueling pod on each wing. The center hose could refuel any probe-equipped aircraft, the wing pods could refuel the more maneuverable fighter/ground attack types.
[[File:Wtaf-routes-1964.jpg|thumb|Route map for [[Military Air Transport Service|MATS (West)]] 1964]]
A byproduct of this development effort and the building of large numbers of tankers was that these tankers were also available to refuel [[cargo aircraft]], [[fighter aircraft]], and [[ground attack aircraft]], in addition to bombers, for ferrying to distant theaters of operations. This was much used during the [[Vietnam War]], when many aircraft could not have covered the transoceanic distances without aerial refueling, even with intermediate bases such as [[Hickam Air Force Base]], Hawaii and [[Kadena Air Base]],  Okinawa. In addition to allowing the transport of the aircraft themselves, the cargo aircraft could also carry [[matériel]], supplies, and personnel to Vietnam without landing to refuel. KC-135s were also frequently used for refueling of air combat missions from air bases in Thailand.

The USAF [[SR-71 Blackbird]] strategic reconnaissance aircraft made frequent use of air-to-air refueling. Indeed, design considerations of the aircraft made its mission impossible without aerial refueling. Based at [[Beale AFB]] in central [[California]], SR-71s had to be forward-deployed to Europe and Japan prior to flying actual reconnaissance missions. These trans-Pacific and trans-Atlantic flights during deployment were impossible without aerial refueling. The SR-71's designers traded takeoff performance for better high-speed, high-altitude performance, necessitating takeoff with less-than-full fuel tanks from even the longest runways. Once airborne, the Blackbird would accelerate to supersonic speed using afterburners to facilitate structural heating and expansion. The magnitude of temperature changes experienced by the SR-71, from parked to its maximum speed, resulted in significant expansion of its structural parts in cruise flight. To allow for the expansion, the Blackbird's parts had to fit loosely when cold, so loosely, in fact, that the Blackbird constantly leaked fuel before heating expanded the airframe enough to seal its fuel tanks. Following the supersonic dash the SR-71 would then rendezvous with a tanker to fill its now nearly empty tanks before proceeding on its mission. This was referred to as the ''LTTR'' (for "Launch To Tanker Rendezvous") profile. LTTR had the added advantage of providing an operational test of the Blackbird's refueling capability within minutes after takeoff, enabling a Return-To-Launch-Site abort capability if necessary. At its most efficient altitude and speed, the Blackbird was capable of flying for many hours without refueling. The SR-71 used a special fuel, [[JP-7]], with a very high [[flash point]] to withstand the extreme skin temperatures generated during Mach 3+ cruise flight.<ref name=SR-71.org>{{cite web|title=Lockheed SR-71 Blackbird|url=http://www.sr-71.org/blackbird/sr-71/|access-date=8 February 2014|archive-date=17 March 2010|archive-url=https://web.archive.org/web/20100317090246/http://www.sr-71.org/blackbird/sr-71/|url-status=live}}</ref> While JP-7 could be used by other aircraft, its burn characteristics posed problems in certain situations (such as high-altitude, emergency engine starts) that made it less than optimal for aircraft other than the SR-71.

Normally, all the fuel aboard a tanker aircraft may be either offloaded, or burned by the tanker as necessary. To make this possible, the KC-135 fuel system incorporated gravity draining and pumps to allow moving fuel from tank to tank depending on mission needs. Mixing JP-7 with JP-4 or Jet A, however, rendered it unsuitable for use by the SR-71, so the Air Force commissioned a specially modified KC-135 variant, the [[KC-135#Variants|KC-135Q]], which included changes to the fuel system and operating procedures preventing inadvertent inflight mixing of fuel intended for offload with fuel intended for use by the tanker. SR-71 aircraft were refueled exclusively by KC-135Q tankers.

[[File:Refuelling a Sukhoi Su-34 (cropped).jpg|thumb|A [[Russian Air Force]] [[Sukhoi Su-34]] takes on fuel through a Probe-and-drogue system]]

===Tactical===
Tankers are considered "[[force multipliers]]", because they convey considerable tactical advantages. Primarily, aerial refueling adds to the combat radius of attack, fighter and bombers aircraft, and allows patrol aircraft to remain airborne longer, thereby reducing the number of aircraft necessary to accomplish a given mission. Aerial refueling can also mitigate basing issues that might otherwise place limitations on combat [[Payload (air and space craft)|payload]]. Combat aircraft operating from airfields with shorter runways must limit their takeoff weight, which could mean a choice between range (fuel) and combat payload (munitions). Aerial refueling, however, eliminates many of these basing difficulties because a combat aircraft can take off with a full combat payload and refuel immediately.

==Operational history==
===Cold War===
Even as the first practical methods for aerial refueling were being developed, military planners had already envisioned what missions could be greatly enhanced by using such techniques. In the emerging [[Cold War]] climate of the late 1940s, the ability for bombers to perform increasingly long distance missions would enable targets to be struck even from air bases on a different continent. Thus, it became commonplace for [[nuclear weapon|nuclear-armed]] [[strategic bomber]]s to be equipped with aerial refueling apparatus and for it to be used to facilitate long distance patrols.<ref name = "b58 blunder">{{cite web |url = https://nationalinterest.org/feature/the-b-58-hustler-americas-cold-war-nuclear-bomber-blunder-16547 |title = The B-58 Hustler: America's Cold War Nuclear Bomber Blunder |publisher = nationalinterest.org |first = Robert |last = Farley |date = 10 June 2016 |access-date = 30 March 2021 |archive-date = 23 April 2021 |archive-url = https://web.archive.org/web/20210423090655/https://nationalinterest.org/feature/the-b-58-hustler-americas-cold-war-nuclear-bomber-blunder-16547 |url-status = live }}</ref>

During the late 1950s, aerial refueling had become so prevalent amongst the bombers operated by the US Air Force's [[Strategic Air Command]] that many, such as the [[Convair B-58 Hustler]], would operate largely or entirely out of bases in the continental United States while maintaining strategic reach.<ref name = "b58 blunder"/> This practice was promoted to address security concerns as well as diplomatic objections from some overseas states that did not want nuclear weapons kept on their soil.<ref name = "b58 blunder"/> In one early demonstration of the [[Boeing B-52 Stratofortress]]'s global reach, performed between 16 and 18 January 1957, three B-52Bs made a [[non-stop flight]] around the world during ''[[Operation Power Flite]]'', during which 24,325&nbsp;miles (21,145&nbsp;nmi, 39,165&nbsp;km) was covered in 45 hours 19 minutes (536.8 smph) with multiple in-flight refuelings being performed from KC-97s.<ref>Condor 1994, p. 42.</ref><ref name=knaack_p243>Knaack 1988, p. 243.</ref>

While development of the [[Avro Vulcan]] strategic bomber was underway, British officials recognised that its operational flexibility could be improved by the provision of in-flight refueling equipment.<ref>Wynn 1997, p. 154.</ref> Accordingly, from the 16th aircraft to be completed onwards, the Vulcan was furnished with in-flight refueling receiving equipment.<ref>Wynn 1997, p. 155.</ref><ref name = 'brookes49'>Brookes and Davey 2009, p. 49.</ref> While continuous airborne patrols were flown by the RAF for a time, these were deemed to be untenable, and the refueling mechanisms across the Vulcan fleet largely fell into disuse during the 1960s.<ref name = 'brookes49'/> When the RAF chose to optimise its bomber fleet away from high-altitude flight and towards low-level penetration missions, bombers such as the [[Handley Page Victor]] were fitted with aerial refueling probes and additional fuel tanks to counter the decreased range from the shift in flight profile.<ref name="Steel p241">Rodwell ''Flight'' 13 February 1964, p. 241.</ref><ref>Windle and Bowman 2009, p. 21.</ref>

During the mid-1950s, to deliver France's independent [[Mutual assured destruction|nuclear deterrent]], work commenced on what would become the [[Dassault Mirage IV]] supersonic bomber.<ref name="Gunston, Bill 1973. p104">Gunston 1973, p. 104.</ref><ref name = "bomber 196">Gunston and Gilchrist 1993, p. 196.</ref> The dimensions of this bomber was greatly determined by the viability of aerial refueling, with work on an enlarged variant of the Mirage IV ultimately being aborted in favour of a greater reliance upon aerial tanker aircraft instead.<ref name="Gunston, Bill 1973. p109">Gunston 1973, p. 109.</ref> In order to refuel the Mirage IVA fleet, France purchased 14 (12 plus 2 spares) US Boeing [[C-135]]F [[Tanker (aircraft)|tankers]].<ref name="Gunston, Bill 1973. p104"/> Mirage IVAs also often operated in pairs, with one aircraft carrying a weapon and the other carrying fuel tanks and a buddy refueling pack, allowing it to refuel its partner en route to the target.<ref name = "bomber 200">Gunston and Gilchrist 1993, p. 200.</ref> While able to strike at numerous targets inside of the Soviet Union, the inability for the Mirage IV to return from some missions had been a point of controversy during the aircraft's design phase.<ref>{{citation |last=Dumoulin |first=André |title=La dissuasion nucléaire française en posture méditerranéenne |journal=Les Cahiers du RMES |volume=II |number=1 |url=http://www.rmes.be/CDR3.pdf |pages=5–12 |quote=(p. 5) Certes, la posture méditerranéenne ne pouvait totalement résoudre la question de l'autonomie après le largage de la bombe à gravité AN-21 puis AN-22, et il était imaginé, au pire, des vols «kamikaze» jusqu'aux cibles russes mais également des profils de vols de retour avec planification des zones de crash, avec l'abandon de l'équipage au-dessus de territoires alliés. |access-date=18 October 2010 |url-status=dead |archive-url=https://web.archive.org/web/20120313212811/http://www.rmes.be/CDR3.pdf |archive-date=13 March 2012 }}</ref><ref name = "bomber 199-200">Gunston and Gilchrist 1993, pp. 196–197.</ref>

=== Korean War ===

On 6 July 1951, the first combat air refueling of fighter-type aircraft took place over Korea. Three RF-80As launched from Taegu with the modified tip-tanks and rendezvoused with a tanker offshore of Wonsan, North Korea. Through in-flight refueling, the RF-80s effectively doubled their range, which enabled them to photograph valuable targets in North Korea.<ref>{{cite web |url=https://www.amc.af.mil/News/Article-Display/Article/147244/history-of-aerial-refueling-fueling-the-fighters/#:~:text=On%20July%206%2C%201951%2C%20the,aircraft%20took%20place%20over%20Korea.&text=Through%20in%2Dflight%20refueling%2C%20the,valuable%20targets%20in%20North%20Korea |title=History of aerial refueling: Fueling the fighters |work=Air Mobility Command |publisher=United States Air Mobility Command |date=15 April 2009 |access-date=6 July 2021 |url-status=live|archive-url=https://web.archive.org/web/20171005084627/http://www.amc.af.mil:80/News/Article-Display/Article/147244/history-of-aerial-refueling-fueling-the-fighters/ |archive-date=5 October 2017 }}</ref><ref>{{Cite web |url=http://www.rb-29.net/html/60romney01.htm |title=First USAF Flight Refueling in Combat |access-date=6 December 2020 |archive-date=11 April 2017 |archive-url=https://web.archive.org/web/20170411065207/http://www.rb-29.net/HTML/60romney01.htm |url-status=dead }}</ref>

=== Vietnam War ===
[[File:HC-130P refuels HH-3E over Southeast Asia (cropped).jpg|thumb|HC-130P refuels HH-3E over Southeast Asia]]
During the [[Vietnam War]], it was common for USAF fighter-bombers flying from [[Thailand]] to [[North Vietnam]] to refuel from KC-135s en route to their target. Besides extending their range, this enabled the [[F-105]]s and [[F-4 Phantom]]s to carry more bombs and rockets. Tankers were also available for refueling on the way back if necessary. In addition to ferrying aircraft across the [[Pacific Ocean]], aerial refueling made it possible for battle-damaged fighters, with heavily leaking fuel tanks, to hook up to the tankers and let the tanker feed its engine(s) until the point where they could glide to the base and land. This saved numerous aircraft. {{citation needed|date=December 2011}}

The US Navy frequently used carrier-based aerial tankers like the [[A-3 Skywarrior|KA-3 Skywarrior]] to refuel Navy and Marine aircraft such as the F-4, [[A-4 Skyhawk]], [[A-6 Intruder]], and [[A-7 Corsair II]]. This was particularly useful when a pilot returning from an airstrike was having difficulty landing and was running low on [[jet fuel]]. This gave them fuel for more attempts at landing for a successful "trap" on an aircraft carrier. The KA-3 could also refuel fighters on extended Combat Air Patrol. USMC jets based in South Vietnam and Thailand also used USMC [[KC-130 Hercules]] transports for air-to-air refueling on missions.

During late August 1970, a pair of [[Sikorsky CH-53 Sea Stallion|HH-53C]] helicopters performed the first Trans-Pacific flight by a helicopter, flying from [[Eglin AFB]] in Florida to [[Danang]] in South Vietnam. In addition to making multiple en route stops to refuel on the ground, aerial refueling was also used in this display of the type's long-range capabilities. The flight proved to be roughly four times faster than the traditional dispatching of rotorcraft to the theatre by ship.<ref name = "sikarchive s-65">{{cite web |url = https://www.sikorskyarchives.com/S-65H-53D%20SEA%20STALLION.php |title = S-65/H-53A/D Sea Stallion/ H-53E Super Stallion |publisher = sikorskyarchives.com |access-date = 28 March 2021 |archive-date = 23 March 2022 |archive-url = https://web.archive.org/web/20220323201110/https://www.sikorskyarchives.com/S-65H-53D%20SEA%20STALLION.php |url-status = live }}</ref>

=== Middle East ===

During the 1980s [[Iran–Iraq War]], the Iranian Air Force maintained at least one KC 707-3J9C aerial tanker, which the Islamic Republic had inherited from the Shah's government. This was used most effectively on 4 April 1981, refueling eight IRIAF F-4 Phantoms on long-range sorties into Iraq to [[H-3 airstrike|bomb the H-3 Al Walid airfield]] near the Jordanian border, destroying 27–50 Iraqi fighter jets and bombers.<ref>{{cite web |url = http://iiaf.net/stories/warstories/s1.html |title = Assault on Al-Wallid |website = Imperial Iraniasn Air Force |access-date = 9 September 2012 |archive-url = https://web.archive.org/web/20171011172153/http://iiaf.net/stories/warstories/s1.html |archive-date = 11 October 2017 |url-status = live }}</ref><ref>Nadimi, Farzin. ''F-4 Phantom.'' Air Forces Monthly Special, {{ISBN|0-946219-46-X}}. p. 77.</ref> However, the Iranian Air Force was forced to cancel its 180-day air offensive and attempts to control Iranian [[airspace]] due to unsustainable rates of attrition.<ref name="csis 5">{{cite web |last=Cordesman |first=Anthony |title=Lessons of Modern Warfare: The Iran Iraq War Chapter V |url=http://csis.org/files/media/csis/pubs/9005lessonsiraniraqii-chap05.pdf |access-date=4 May 2013 |archive-url=https://web.archive.org/web/20090911152946/http://csis.org/files/media/csis/pubs/9005lessonsiraniraqii-chap05.pdf |archive-date=11 September 2009 |url-status=live }}</ref><ref name="Cooper Blinders">{{cite web |last=Cooper |first=Tom |title=Bombed by Blinders Part 1 |url=http://www.acig.info/CMS/?option=com_content&task=view&id=247&Itemid=47 |access-date=20 April 2013 |archive-url=https://web.archive.org/web/20141006104450/http://www.acig.info/CMS/?option=com_content&task=view&id=247&Itemid=47 |archive-date=6 October 2014 |url-status=live }}</ref>

The [[Israeli Air Force]] has a fleet of Boeing 707s equipped with a boom refueling system similar to the KC-135, this system has the Israeli name ''Ram'', used to refuel and extend the range of fighter bombers such as the F-15I and F-16I for deterrent and strike missions, they are nearing 60 years old and Israel does not disclose the number of tankers in their fleet.<ref>{{cite web|url=https://www.youtube.com/watch?v=JW1lHcbIXYM| archive-url=https://ghostarchive.org/varchive/youtube/20211107/JW1lHcbIXYM| archive-date=7 November 2021 | url-status=live|title=תדלוק אווירי|last=Israeli Air Force|date=10 October 2013|access-date=19 November 2016|via=YouTube}}{{cbignore}}</ref><ref>{{cite web|url=http://www.defensemedianetwork.com/stories/first-strike-on-irans-nuclear-facilities-part-1/|title=Israel's First Strike on Iran's Nuclear Facilities – Part 1 - Defense Media Network|access-date=19 November 2016|archive-date=20 November 2016|archive-url=https://web.archive.org/web/20161120010359/http://www.defensemedianetwork.com/stories/first-strike-on-irans-nuclear-facilities-part-1/|url-status=live}}</ref><ref name="jpost.com">{{Cite web|url=https://www.jpost.com/israel-news/us-rejects-israeli-request-for-tanker-aircraft-as-iran-plans-advance-688600|title=US rejects Israeli request for tanker aircraft as Iran plans advance|date=13 December 2021 |access-date=13 December 2021|archive-date=13 December 2021|archive-url=https://web.archive.org/web/20211213095915/https://www.jpost.com/israel-news/us-rejects-israeli-request-for-tanker-aircraft-as-iran-plans-advance-688600|url-status=live}}</ref> In 1985, Israeli [[F-15]]s used heavily modified [[Boeing 707]] aircraft to provide aerial refueling over the [[Mediterranean Sea]] in order to extend their range for [[Operation Wooden Leg]], an air raid on the headquarters of the [[Palestine Liberation Organization]] (PLO) near [[Tunis]], [[Tunisia]], that necessitated a 2,000&nbsp;km flight.{{sfn|Bergman|2018|page=306}} As of 2021 Israel has ordered four of a planned eight [[Boeing KC-46 Pegasus]] boom refueling tankers and has requested that the first two aircraft be fast-tracked for delivery in 2022 when they were to be delivered in 2023.  The Jerusalem Post reports that Israeli commanders have made this request to enhance the strategic deterrence against Iran, the same article reports that the US, whose air force is also taking its first deliveries of the aircraft type, has refused to move forward the deliveries while supporting Israel's deterrence; the Jpost editor writing "The US State Department approved the possible sale of up to eight KC-46 tanker aircraft and related equipment to Israel for an estimated cost of $2.4 billion last March(i.e. 5/2020), marking the first time that Washington has allowed Jerusalem to buy new tankers."<ref name="jpost.com"/>

=== Falklands War ===

During the [[Falklands War]], aerial refueling played a vital role in all of the successful Argentine attacks against the [[Royal Navy]]. The [[Argentine Air Force]] had only two KC-130H Hercules available and they were used to refuel both Air Force and Navy [[A-4 Skyhawk]]s and Navy [[Super Etendard]]s in their [[Exocet]] strikes. The Hercules on several occasions approached the islands (where the [[Sea Harrier]]s were in patrol) to search and guide the A-4s in their returning flights. On one of those flights (callsign ''Jaguar'') one of the KC-130s went to rescue a damaged A-4 and delivered {{convert|39000|lb|abbr=on}} of fuel while carrying it to its airfield at [[Puerto San Julián|San Julian]]. However, the [[Mirage III]]s and [[IAI Nesher|Daggers]] lack of air refueling capability prevented them from achieving better results. The Mirages were unable to reach the islands with a strike payload, and the Daggers could do so only for a five-minute strike flight.

On the British side, air refueling was carried out by the [[Handley Page Victor]] K.2 and, after the Argentine surrender, by modified C-130 Hercules tankers. These aircraft aided deployments from the UK to the [[Ascension Island]] staging post in the Atlantic and further deployments south of bomber, transport and maritime patrol aircraft.<ref name="Falklands">[http://www.raf.mod.uk/falklands/bb.html "The Falkland Islands: A history of the 1982 conflict."] ''Royal Air Force'', 29 April 2010. {{webarchive |url=https://web.archive.org/web/20070318044222/http://www.raf.mod.uk/falklands/bb.html |date=18 March 2007 }}</ref> The most famous refueling missions were the 8,000&nbsp;nmi (15,000&nbsp;km) "[[Operation Black Buck]]" sorties which used 14 Victor tankers to allow an [[Avro Vulcan]] bomber (with a flying reserve bomber) to attack the Argentine-captured airfield at Port Stanley on the [[Falkland Islands]]. With all the aircraft flying from Ascension, the tankers themselves needed refueling.<ref>Darling 2007, pp. 116–117.</ref><ref>[https://books.google.com/books?id=wdM5wJlVhpcC&pg=PA119 Kev Darling, ''RAR Illustrated: Avro Vulcan Part 1''], Big Bird Publications 2007, {{ISBN|978-1-84799-237-6}} (p.119)</ref><ref>[http://webarchive.nationalarchives.gov.uk/20071104162619/http://www.operations.mod.uk/falklands25/NARRATIVE%20OF%20RAF%20CONTRIBUTION.doc "Narrative of RAF Contribution to the Falklands Campaign."] ''The National Archives'', Retrieved: 20 April 2014.</ref> The raids were the longest-range bombing raids in history until surpassed by the [[Boeing B-52]]s flying from the States to bomb Iraq in the 1991 [[Gulf War]] and later [[B-2 Spirit|B-2]] flights.<ref name="stbull84">Bull 2004, p. 84.</ref>

=== Gulf War ===

During the time of Operation Desert Shield, the military buildup to the Persian Gulf War, US Air Force Boeing KC-135s & McDonnell Douglas KC-10As, and USMC KC-130 Hercules aircraft were deployed to forward air bases in [[England]], [[Diego Garcia]], and [[Saudi Arabia]]. Aircraft stationed in Saudi Arabia normally maintained an orbit in the [[Saudi–Iraqi neutral zone]], informally known as "Frisbee", and refueled coalition aircraft whenever necessary. Two side by side tracks over central Saudi Arabia called "Prune" and "Raisin" featured 2–4 basket equipped KC-135 tankers each and were used by Navy aircraft from the [[Red Sea Battle Force]]. Large Navy strike groups from the Red Sea would send A-6 tankers to the Prune and Raisin tracks ahead of the strike aircraft arriving to top off and take up station to the right of the Air Force tankers thereby providing an additional tanking point. RAF Handley Page Victor and [[Vickers VC10]] tankers were also used to refuel British and coalition aircraft and were popular with the US Navy for their docile basket behavior and having three point refueling stations. An additional track was maintained close to the northwest border for the E-3 AWACS aircraft and any Navy aircraft needing emergency fuel. These 24-hour air-refueling zones enabled the intense air campaign during Desert Storm. An additional 24/7 tanker presence was maintained over the Red Sea itself to refuel Navy F-14 Tomcats maintaining [[Combat Air Patrol]] tracks. During the conflict's final week, KC-10s moved inside Iraq to support barrier CAP missions set up to block Iraqi fighters from escaping to Iran.

[[File:Exercise Angel Thunder 2014 140512-F-IE715-1625.jpg|thumb|right|A [[French Air Force]] [[Eurocopter EC725|EC725]] is refueled by a [[Lockheed HC-130]] during Exercise Angel Thunder]]
On 16–17 January 1991, the first combat sortie of Operation Desert Storm, and the longest combat sortie in history at that time, was launched from [[Barksdale AFB, Louisiana]]. Seven B-52Gs flew a thirty-five-hour mission to the region and back to launch 35 [[AGM-86 ALCM|Boeing Air Launched Cruise Missile]]s (ALCMs) with the surprise use of conventional warheads. This attack, which successfully destroyed 85–95 percent of intended targets, would have been impossible without the support of refueling tankers.<ref>{{cite web |url-status=dead |url=http://www.barksdale.af.mil/library/factsheets/factsheet.asp?id=4553 |title=Factsheets: 2nd Bomb Wing History |archive-url=https://web.archive.org/web/20090926175703/http://www.barksdale.af.mil/library/factsheets/factsheet.asp?id=4553 |archive-date=26 September 2009 |website= Barksdale Air Force Base|publisher=United States Air Force |access-date=19 September 2011}}</ref><ref>[https://www.flightglobal.com/news/articles/boeing-b-52-evolves-again-with-guided-weapons-launch-420874/ Boeing B-52 evolves again with guided weapons launcher] {{Webarchive|url=https://web.archive.org/web/20190820130325/https://www.flightglobal.com/news/articles/boeing-b-52-evolves-again-with-guided-weapons-launch-420874/ |date=20 August 2019 }} – Flightglobal.com, 15 January 2016</ref>

An extremely useful tanker in Desert Storm was the USAF's KC-10A Extender. Besides being larger than the other tankers deployed, the KC-10A is equipped with the USAF "boom" refueling and also the "hose-and-drogue" system, enabling it to refuel not only USAF aircraft, and also USMC and US Navy jets that use the "probe-and-drogue" system, and also allied aircraft, such as those from the UK and Saudi Arabia. KC-135s may be equipped with a drogue depending on the mission profile. With a full jet fuel load, the KC-10A is capable of flying from a base on the American east coast, flying nonstop to Europe, transferring a considerable amount of fuel to other aircraft, and returning to its home base without landing anywhere else.{{Citation needed|date=March 2021}}

On 24 January 1991, the [[Iraqi Air Force]] launched the [[Attack on Ras Tanura]], an attempt to bomb the Ras Tanura oil facility in Saudi Arabia. On their way to the target, the Iraqi attack aircraft were refueled by tanker at an altitude of 100 meters. The attack ultimately failed, with two aircraft turning back and the remaining two shot down.<ref name="Woods">{{cite book |last1=Woods |first1=Kevin |title=Iraqi Perspectives Project Phase II Um Al-Ma'arik (The Mother of All Battles): Operational and Strategic Insights from an Iraqi Perspective |date=May 2008 |publisher=Institute for Defense Analysis |page=199 |edition=First}}</ref><ref name="Francoma">{{cite book |last1=Francoma |first1=Rick |title=Ally to Adversary: An Eyewitness Account of Iraq's Fall From Grace |date=1999 |publisher=Naval Institute Press |isbn=1557502811 |page=106}}</ref>

=== Centennial Contact ===
On 27 June 2023 the [[United States Air Force]], including the Air National Guard, commemorated the 100-year anniversary of the first aerial refueling by holding "Operation Centennial Contact." Aircraft from various bases conducted aerial refueling exercises across the United States, as well as conducting flyovers in 50 states.<ref name="AMC celebrates 100th year of air refueling with community flyovers across the US">{{cite web |url=https://www.af.mil/News/Article-Display/Article/3438220/amc-celebrates-100th-year-of-air-refueling-with-community-flyovers-across-the-us/ |title=AMC celebrates 100th year of air refueling with community flyovers across the US |publisher=Air Mobility Command Public Affairs |date=June 25, 2023 |website=af.mil |access-date=June 25, 2023}}</ref> 152 aircraft were slated to participate in the operation, with 82 tanker aircraft providing refueling support to 70 other participating aircraft.<ref name="Wild blue yonder: Air Force refueling flyover event visible in Southern Utah">{{cite web |url=https://www.stgeorgeutah.com/news/archive/2023/06/26/prc-wild-blue-yonder-air-force-refueling-flyover-event-visible-in-southern-utah/ |title=Wild blue yonder: Air Force refueling flyover event visible in Southern Utah |date=June 26, 2023 |website=St George News |access-date=June 27, 2023}}
</ref>

The aircraft participating included 49 [[Boeing KC-135 Stratotanker]]; 29 [[Boeing KC-46 Pegasus]]; four [[McDonnell Douglas KC-10 Extender]]s, and aircraft receiving fuel included 
21 [[Lockheed C-130 Hercules]]; 13 [[Boeing C-17 Globemaster III]]; ten [[McDonnell Douglas F-15 Eagle]]; eight [[Lockheed Martin F-22 Raptor]]; six [[Fairchild Republic A-10 Thunderbolt II]]; five [[General Dynamics F-16 Fighting Falcon]]s; four [[Lockheed Martin F-35 Lightning II]]; two [[Boeing B-52 Stratofortress]]es; and one [[Lockheed C-5 Galaxy]].
<ref name="Wild blue yonder: Air Force refueling flyover event visible in Southern Utah" />

==Helicopters==
Helicopter in-flight refueling (HIFR) is a variation of aerial refueling when a naval [[helicopter]] approaches a warship (not necessarily suited for landing operations) and receives fuel through the cabin while hovering.  Alternatively, some helicopters like the [[HH-60 Pave Hawk]] are equipped with a probe extending out the front can be refueled from a drogue-equipped tanker aircraft in a similar manner to fixed-wing aircraft by matching a high forward speed for a helicopter to a slow speed for the fixed-wing tanker.

==Longest crewed flight record==
A mission modified [[Cessna 172 Skyhawk]] with a crew of two set the world record for the longest continuous crewed flight without landing of 64 days, 22 hours, 19 minutes, and five seconds in 1958. A Ford truck was outfitted with a fuel pump, tank, and other paraphernalia required to support the aircraft in flight. The publicity flight for a Las Vegas area hotel ended when the aircraft's performance had degraded to the point where the Cessna had difficulty climbing away from the refueling vehicle.<ref>{{cite web|url=http://untoldvalor.blogspot.co.il/2008/07/plane-that-flew-for-62-days-and-t-bird.html|title=The Plane that Flew for 62 Days and the T-Bird that Saved the Day|date=29 July 2008|access-date=19 November 2016|archive-date=20 November 2016|archive-url=https://web.archive.org/web/20161120010326/http://untoldvalor.blogspot.co.il/2008/07/plane-that-flew-for-62-days-and-t-bird.html|url-status=live}}</ref><ref>{{cite web|url=http://www.aopa.org/News-and-Video/All-News/2008/March/1/Endurance-Test-Circa-1958|title=Endurance Test, Circa 1958|date=3 January 2008|access-date=19 November 2016|archive-date=5 April 2016|archive-url=https://web.archive.org/web/20160405111447/http://www.aopa.org/News-and-Video/All-News/2008/March/1/Endurance-Test-Circa-1958|url-status=live}}</ref>

==Developments==

* Commercial tankers are occasionally used by military forces. The [[Omega Aerial Refueling Services]] company<ref>{{cite web|url=http://www.omegaairrefueling.com/vms/|title=Omega Air Refueling|access-date=19 November 2016|archive-date=12 May 2015|archive-url=https://web.archive.org/web/20150512202232/http://www.omegaairrefueling.com/vms/|url-status=dead}}</ref> and Metrea Strategic Mobility<ref>{{Cite web |title=Metrea Strategic Mobility |url=https://metrea.aero/msm/ |access-date=31 January 2023 |website=Metrea |language=en-US |archive-date=31 January 2023 |archive-url=https://web.archive.org/web/20230131230649/https://metrea.aero/msm/ |url-status=live }}</ref> are contracted by the US Navy. In June 2023, Metrea completed the first commercial refueling of the US Air Force.<ref>{{Cite web |last=Trevithick |first=Joseph |date=2023-07-12 |title=Private Aerial Refueling Tanker Has Gassed Up An Air Force Plane For The First Time |url=https://www.thedrive.com/the-war-zone/private-aerial-refueling-tanker-has-gassed-up-an-air-force-plane-for-the-first-time |access-date=2023-07-16 |website=The Drive |language=en}}</ref>
* [[Automated aerial refueling|Autonomous (hands off) refueling]] using probe/drogue systems was investigated by [[NASA]], potentially for use by [[unmanned aerial vehicle]]s in the [[KQ-X]] program.<ref>{{cite web|url=http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog:27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post:b7a0eae1-e0db-4cf5-b169-2c5633272ceb|title=Ares|access-date=19 November 2016|archive-date=23 February 2012|archive-url=https://web.archive.org/web/20120223115212/http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog:27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post:b7a0eae1-e0db-4cf5-b169-2c5633272ceb|url-status=live}}</ref>
{{-}}

==Operators==
[[File:KC-30 A39-002 refuelling an USAF F-16 (cropped).jpg|thumb|A [[Royal Australian Air Force|RAAF]] KC-30 refuels a USAF [[F-16]]]]
;{{ALG}}
*[[Algerian Air Force]]<ref name="World Air Forces 2020">{{cite web|url= https://www.flightglobal.com/reports/world-air-forces-2020/135665.article|title= World Air Forces 2020|publisher= Flightglobal Insight|year= 2020|access-date= 1 April 2020|url-access= registration|archive-date= 10 December 2019|archive-url= https://web.archive.org/web/20191210142102/https://www.flightglobal.com/reports/world-air-forces-2020/135665.article|url-status= live}}</ref>

;{{ARG}} 
*[[Argentine Air Force]]<ref name="World Air Forces 2020"/>

;{{AUS}}
*[[Royal Australian Air Force]]<ref name="World Air Forces 2020"/> 
;{{BRA}}
*[[Brazilian Air Force]]<ref name="World Air Forces 2020"/>

;{{CAN}}
*[[Royal Canadian Air Force]]<ref name="World Air Forces 2020"/> 
;{{CHL}}
*[[Chilean Air Force]]<ref name="World Air Forces 2020"/>

;{{CHN}}
*[[People's Liberation Army Air Force]]<ref name="World Air Forces 2020"/>

;{{COL}}
*[[Colombian Air Force]]<ref name="World Air Forces 2020"/>

;{{EGY}}
*[[Egyptian Air Force]]<ref>{{cite web |url=https://www.janes.com/defence-news/news-detail/egypt-demonstrates-aerial-refuelling-for-combat-aircraft |title=Egypt demonstrates aerial refuelling for combat aircraft |work=Janes.com |last=Jennings |first=Greg |date=14 January 2020 |access-date=6 July 2021 |url-status=live|archive-url=https://web.archive.org/web/20200906231759/https://www.janes.com/defence-news/news-detail/egypt-demonstrates-aerial-refuelling-for-combat-aircraft |archive-date=6 September 2020 }}</ref>

;{{FRA}}
*[[French Air Force]]<ref name="World Air Forces 2020"/>
*[[French Naval Aviation|French Navy]]
[[File:Ilyushin Il-78MKI (RK-3452).jpg|thumb|An [[Indian Air Force|IAF]] [[Ilyushin Il-78| Ilyushin Il-78MKI]] provides mid-air refueling to two [[Dassault Mirage 2000|Mirage 2000]]]]
;{{GER}}
*[[German Air Force]]<ref name="World Air Forces 2020"/>

;{{IND}}
*[[Indian Air Force]]<ref name="World Air Forces 2020"/>

;{{flag|Indonesia}}
*[[Indonesian Air Force]]<ref>{{cite web |url=https://adbr.com.au/indonesia-seeks-new-heavy-air-refuelling-tanker/ |title=Indonesia seeks new heavy air refuelling tanker |website=ABDR |last=McLaughlin |first=Andrew |date=22 January 2018 |access-date=6 July 2021 |url-status=live|archive-url=https://web.archive.org/web/20180403201148/http://adbr.com.au/indonesia-seeks-new-heavy-air-refuelling-tanker/ |archive-date=3 April 2018 }}</ref>

;{{IRN}}
*[[Islamic Republic of Iran Air Force]]<ref name="World Air Forces 2020"/>

;{{ISR}}
*[[Israeli Air Force]]<ref name="World Air Forces 2020"/>

;{{ITA}}
*[[Italian Air Force]]<ref name="World Air Forces 2020"/>

;{{JPN}}
*[[Japan Air Self-Defense Force]]<ref name="World Air Forces 2020"/>

;{{KOR}}
*[[Republic of Korea Air Force]]<ref name="World Air Forces 2020"/>

;{{KWT}}
* [[Kuwait Air Force]]<ref name="World Air Forces 2020"/>

;{{MAS}}
*[[Royal Malaysian Air Force]]<ref name="World Air Forces 2020"/>
[[File:Saab JAS-39 of the Swedish Air Force undergoing inflight refuelling from a TP 84 Hercules (cropped).jpg|thumb|Two [[Saab JAS 39 Gripen|Saab JAS-39 Gripen]] of the [[Swedish Air Force]] undergoing inflight refueling.]]
;{{MAR}}
*[[Royal Moroccan Air Force]]<ref name="World Air Forces 2020"/>

;{{NED}}
*[[Royal Netherlands Air Force]]<ref name="World Air Forces 2020"/>

;{{PAK}}
*[[Pakistan Air Force]]<ref name="World Air Forces 2020"/>
'''{{PRT}}'''

* [[Portuguese Air Force]]<ref>{{Cite web |last=Sharma |first=Soumya |date=2022-10-17 |title=Portuguese Air Force's first KC-390 aircraft arrives in Portugal |url=https://www.airforce-technology.com/news/portuguese-first-kc390-arrives-portugal/ |access-date=2023-09-16 |website=Airforce Technology |language=en-US}}</ref>
;{{RUS}}
[[File:Tu-95 filling rod and filling cone from Il-78M aircraft.png|thumb|Tu-95М filling rod and filling cone from Il-78M aircraft]]
*[[Russian Air Force]]<ref name="World Air Forces 2020"/>

;{{SIN}}
*[[Republic of Singapore Air Force]]<ref name="World Air Forces 2020"/>

;{{ESP}}
*[[Spanish Air and Space Force]]<ref name="World Air Forces 2020"/>

;{{SWE}}
*[[Swedish Air Force]]<ref name="World Air Forces 2020"/>

;{{TUR}}
*[[Turkish Air Force]]<ref name="World Air Forces 2020"/>

;{{UAE}}
*[[United Arab Emirates Air Force]]<ref name="World Air Forces 2020"/>

;{{UK}}
*[[Royal Air Force]]<ref name="World Air Forces 2020"/>

;{{SAU}}
*[[Royal Saudi Air Force]]<ref name="World Air Forces 2020"/>
[[File:KC-46 Refuels B-2 over Edwards AFB.jpg|thumb|A [[Boeing KC-46 Pegasus|KC-46 Pegasus]] refuels a [[Northrop Grumman B-2 Spirit|B-2]] over [[Edwards AFB]]]]
;{{USA}}
*[[United States Air Force]]<ref name="World Air Forces 2020"/>
*[[United States Marine Corps]]<ref name="World Air Forces 2020"/>
*[[United States Navy]]<ref name="World Air Forces 2020"/>

;{{VEN}}
*[[Venezuelan Air Force]]<ref name="World Air Forces 2020"/>

==See also==
* [[Military logistics]]
* [[Propellant depot]]
* [[Underway replenishment]], the transfer of refuel and stores at sea
* [[List of tanker aircraft]]

== Notes ==
{{notelist}}

==References==
===Citations===
{{reflist|30em}}

===Bibliography===
* Bull, Stephen. [https://books.google.com/books?id=EGKATNM4scMC ''Encyclopedia of Military Technology And Innovation.''] Santa Barbara, California: Greenwood Publishing Group, 2004. {{ISBN|978-1-57356-557-8}}.
* Brookes, Andrew and Chris Davey. [https://books.google.com/books?id=pmQXR69pRoIC ''Vulcan Units of The Cold War'' (Osprey Combat Aircraft: 72).] Oxford, UK: Osprey Publishing, 2009. {{ISBN|978-1-84603-297-4}}.
* Condor, Albert E. ''Air Force Gunners (AFGA): The Men Behind the Guns, The History of Enlisted Aerial Gunnery, 1917–1991''. Nashville, Tennessee: Turner Publishing, 1994. {{ISBN|978-1-56311-167-9}}.
* Darling, Kev. [https://books.google.com/books?id=wdM5wJlVhpcC ''Avro Vulcan, Part One'' (RAF Illustrated).] Vale of Glamorgan Wales, UK: Big Bird Aviation Publication, 2007. {{ISBN|978-1-84799-237-6}}.
* {{cite magazine |last=Gardner |first=Brian |title=Flight Refuelling... The Wartime Story |magazine=[[Air Enthusiast]] |date=1984 |issue=25 |pages=34–43, 80 |issn=0143-5450}}
* Gunston, Bill. Bombers of the West. New York: Charles Scribner's and Sons; 1973. {{ISBN|0-7110-0456-0}}.
* Gunston, Bill and Peter Gilchrist. ''Jet Bombers: From the Messerschmitt Me 262 to the Stealth B-2''. Osprey, 1993. {{ISBN|1-85532-258-7}}.
* Knaack, Marcelle Size. [https://media.defense.gov/2010/May/26/2001330264/-1/-1/0/AFD-100526-026.pdf ''Post-World War II Bombers, 1945–1973''.]<!--[https://web.archive.org/web/20040627143458/http://www.airforcehistory.hq.af.mil/Publications/fulltext/encyclopedia_postww2_bombers.pdf ''Post-World War II Bombers, 1945–1973''.] --> Washington, D.C.: Office of Air Force History, 1988. {{ISBN|978-0-16-002260-9}}.
* Rodwell, Robert R. [http://www.flightglobal.com/pdfarchive/view/1964/1964%20-%200386.html "The Steel in the Blue: Last Week's Glimpse of the V-force"]. ''Flight'', 13 February 1964, pp.&nbsp;241–245.
* Windle, Dave and Martin Bowman. ''V Bombers: Vulcan, Valiant and Victor'', Casemate Publishers, 2009. {{ISBN|1-84415-827-6}}.
* Wynn, Humphrey. ''RAF Strategic Nuclear Deterrent Forces: Origins, Roles and Deployment 1946–1969.'' London: The Stationery Office, 1997. {{ISBN|0-11-772833-0}}.
*{{cite book |last1=Cordesman |first1=Anthony H. |last2=Kleiber |first2=Martin |title=Chinese Military Modernization: Force Development and Strategic Capabilities |date=2007 |publisher=[[Center for Strategic and International Studies|CSIS]] |isbn=978-0-89206-496-0 |page=158 |url=https://books.google.com/books?id=JKCBmuTlmfMC |author1-link=Anthony Cordesman |language=en}}
*{{cite book |last1=Bergman |first1=Ronen |title=Rise and Kill First: The Secret History of Israel's Targeted Assassinations |date=30 January 2018 |publisher=Random House Publishing Group |isbn=978-0-679-60468-6 |page=306 |url=https://books.google.com/books?id=3UXKDQAAQBAJ |language=en}}

==External links==
{{commons|Aerial refueling}}
* [https://web.archive.org/web/20060827030959/http://www.centennialofflight.gov/essay/Evolution_of_Technology/refueling/Tech22G1.htm Photo aerial tanking 1929]
* [https://web.archive.org/web/20060519103213/http://www.centennialofflight.gov/essay/Evolution_of_Technology/refueling/Tech22.htm Aerial tanking history]
* [https://web.archive.org/web/20061026104101/http://www.tfot.info/content/view/81/ Airborne rearming], a comprehensive article with video.
* [http://www.ausairpower.net/aar-lift.html Aerial Refueling on APA]
* [http://arsaginc.com/ Air Refueling Systems Advisory Group]
* [http://www.flightglobal.com/pdfarchive/view/1955/1955%20-%201820.html ''Twenty-one Years of Flight Refuelling''], a 1955 [[Flight International|''Flight'']] article on the development of Flight Refuelling Ltd's refueling method.
* [http://www.airforce-technology.com/features/featurethe-worlds-best-aerial-refuelling-aircraft/ World's best aerial refueling aircraft]
* [http://www.tactankers.com/ Tac Tankers Association]
* [http://www2.atalink.org/ Airlift/Tankers Association] {{Webarchive|url=https://web.archive.org/web/20220625223114/https://atalink.org/ |date=25 June 2022 }}

{{Military aircraft types (roles)}}

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{{DEFAULTSORT:Refueling}}
[[Category:Air refueling| ]]
[[Category:Aerial maneuvers|Refueling]]
[[Category:Articles containing video clips]]