The Royal Australian Air Force (RAAF) has worked to provide allies with the air-to-air refuelling capabilities offered by its seven Airbus Defence & Space A330 Multi-Role Tanker Transports (MRTTs).
In recent years the RAAF has used the aircraft – which it designates as the KC-30A – to deepen relationships with close allies and partners and improve interoperability among regional air forces.
Australia’s Department of Defence (DoD) periodically issues statements highlighting new additions to the KC-30A’s roster of recipients.
November 2024 saw Canberra announce that the type would be allowed to refuel aircraft operated by India’s military, namely Boeing P-8I Neptune maritime patrol aircraft – which are broadly similar to the P-8As operated by the RAAF.
A little over a year earlier, in August 2023, an RAAF KC-30A conducted a major refuelling exercise with Lockheed Martin F-16s operated by Indonesia. The work involved over 60 F-16 sorties and 200 successful boom contacts.
May 2023 saw the KC-30A cleared to refuel Japan Air Self-Defense Force (JASDF) Boeing/Mitsubishi F-15Js following 11 flights and 325 boom contacts. The milestone came one year after the KC-30A was cleared to refuel another mainstay of Japanese airpower, the Mitsubishi F-2.
“Air-to-air refuelling is an essential function of fighter aircraft operations and greatly contributes to JASDF-RAAF interoperability,” said the JASDF of the effort.
In addition, Australia has an air-to-air refuelling pact with another Asia-Pacific partner, South Korea. Seoul, for its part, operates four A330 MRTTs.
“This helps further ensure that our two air forces can support one another in the skies, during exercises and training activities and on any future operations,” said a senior RAAF officer on the occasion of the 2022 agreement with Seoul.
“The transfer of fuel when required to sustain and prolong our presence in the air is critical to our aircraft being able to successfully project air power.”
In addition, RAAF KC-30As have worked with aircraft from other partners such as France, the UK, the USA and others.
The type also participated in Operation Okra, Australia’s contribution to a coalition campaign against Islamic State terrorists in Iraq from 2014-2020. The work involved over 1,600 sorties, during which the KC-30A refuelled a broad number of allied types.
The international effort comes on top of the KC-30A’s main work, which is refuelling RAAF types such as the Lockheed F-35A, Boeing EA-18G Growler, F/A-18F Super Hornet, C-17, and P-8A.
While the DoD’s statements and accompanying images make the KC-30A’s international refuelling work look relatively straightforward, a significant amount of work takes place before a foreign aircraft lines up on the MRTT, connects with its boom and takes on fuel.
Squadron Leader Lee McDowall is part of 33 Sqn, which operates the KC-30A from RAAF Amberley south of Brisbane, Queensland. A line air refuelling officer and instructor, he is a subject matter expert on air-to-air refuelling with the KC-30A’s boom.
In addition to his existing role with 33 Sqn, he has also been deployed to Airbus’s facility in Getafe, Spain to work on the MRTT programme there. He is highly conversant with the world of fighter aircraft, having spent time in the back seats of the now-retired RAAF F/A-18B Hornet, as well as in the F/A-18F, of which Australia operates 24. In McDowall’s existing role he handles clearances for new receiver types.
He reveals that a significant body of work goes into clearing overseas partner aircraft to refuel from the KC-30A. Initially there is a conversation between air forces about the desirability of obtaining a clearance to tank from the KC-30A, at which point the effort moves to flight testing.
“We’ve done about fifteen clearances with different kinds of receivers,” says McDowall. “We have a well laid out path to do the testing. It takes about eight to ten flights spread over two or three weeks.”
Before this, McDowall and his RAAF colleagues will work with the flight test agency for the receiving aircraft and develop a joint test plan. This will outline how the test work will progressively assess the extremes of altitude, airspeed, weights, weapons loadouts on the receiver platform, and even the boom elevation. This effort can take two to three months.
Engineers in Australia and for the receiver aircraft conduct a compatibility assessment to confirm that the pairing will be successful in the air.
“The aim of our testing is to assess the compatibility of both aircraft, and there is a list of areas we look at,” he says.
One area is purely mechanical, or the binding between the receiver aircraft’s fuel receptacle in all elevation, roll, and boom telescope positions.
Another area considered is the geometry of the contact. “Is there any risk of our boom coming into contact with antennas or the canopy?” asks McDowall. “Or even the fuselage as the receiver moves around?”
Also assessed are boom handling qualities and the receiver’s handling qualities, and how these might influence each other as the two aircraft get into proximity and make contact via the boom.
“Once we make contact and the tanker starts turning to make an orbit, is the receiver happy back there?”
Apart from aircraft handling, test work also includes several fuel transfers aimed at assessing pressures and flow rates.
Human factors are also assessed. In the MRTT, the air refuelling officer sits in a comfortable seat at a rear-facing console in the cockpit. Wearing 3D goggles linked to a series of cameras located on the jet’s fuselage they fly the boom into the receptacle of the receiving aircraft. This is a major improvement over the ubiquitous Boeing KC-135, in which the boom operator lies on their stomach and guides the boom as they peer through a rearward facing window, with their chin resting on a padded support.
During a 2017 media visit to RAAF Amberley’s KC-30A simulator centre, which is managed by simulator specialist CAE, FlightGlobal – with no prior training – was able to use a sidestick controller to easily guide a simulated boom into the receptacle of an F-35A. The process was intuitive and simple. Other defence journalists – also untrained – enjoyed similar success.
Still, human factors remain critical in air-to-air refuelling, which is fundamentally a highly complex endeavour with a range of potential safety issues. As such, McDowall and his team look at a range of variables that can affect the boom operator’s perception, such as lighting conditions, clouds, and how these interact with the KC-30A’s external lighting, which offers essential cues for receiver aircraft.
Prior to working with a new receiver type, the RAAF will brief pilots on the idiosyncrasies of the KC-30A, and how things may differ from tankers they are used to. Moreover, the attributes of the KC-30A are posted in documentation provided by NATO’s Joint Air Power Competence Centre (JAPCC). Once the KC-30A is cleared to refuel a certain receiver type, operational pilots can use JAPCC resources to help plan refuelling activities with the KC-30A.
“As for the testing process, we start at the heart of the proposed envelope, and check that there are no adverse effects from them or us, and then we incrementally explore different conditions, changing one variable at time,” says McDowall.
Altitudes can range from low level to 35,000ft. For attack jets such as the Fairchild Republic A-10, the KC-30A needs to slow down, while for fighters it needs to go much faster.
“We progress gradually toward the extremes of the envelope we’re trying to achieve. We have only rarely discovered any compatibility concerns, because the jet is designed to be easy to perform refuelling with.”
McDowall adds that receiver pilots are big fans of the KC-30A and are impressed with the amount of fuel it can offload in comparison with other tankers.
The KC-30A, as with MRTTs operated by most other air forces, offers refuelling through the boom and through hose and drogue pods mounted outboard of the aircraft’s engines – GE Aerospace CF6s in the case of RAAF examples. Hose and drogue refuelling, such as for the F/A-18F, requires considerably less clearance work, with receiver aircraft simply nosing their refuelling probe up to the basket.
Despite the intuitive nature of the KC-30A’s refuelling interface within well-defined control laws, the boom is altogether more complicated.
“There’s more people flying different things,” says McDowall. “With hose and drogue, we trail them, and it’s up to the receiver pilot to do his work. With the boom we’re flying it, and it adds just one more, quite large, variable – another person in the loop flying a big thing into their receptacle.”
Asked about what allied aircraft are most challenging to refuel, McDowall feels things have gone very smoothly and that no receiver aircraft type is especially challenging. The main challenge tends to fall in the planning phase, when there is a considerable amount of administration work within the two air forces. Once things move to the flying squadrons, McDowall says things “are pretty easy”.
Still, some receivers are unique. Most allied aircraft, such as the F-35 and F-15, have the receptacle further back behind the cockpit. The US Air Force’s A-10 ground-attack jet and Boeing B-1B bomber, however, have their refuelling receptacle in the nose, forward of the cockpit. The different layout calls for modified procedures.
“This changes the approach that we use, especially in terms of calling out distance to go,” says McDowall.
When refuelling aircraft with fuselage-mounted receptacles, the boom operator has more cues around the fuselage that indicate the distance from the boom. For aircraft that refuel through the nose more guesswork is required.
“But it’s fun. Generally, all receiver types are considered equal, but the unique ones are the most fun for the air refuelling officer, because it’s something different.”
McDowall adds that in addition to its tanking capabilities, the KC-30A can carry 270 passengers and 34t of cargo, making it a key air mobility asset for Australia and allies. To this end, he feels the aircraft is “hugely beneficial” in fostering relationships with Australia’s defence partners.
