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Getting jets to sea – more squadrons, more pilots please

As HMS Queen Elizabeth undergoes initial sea trials there is considerable discussion about her future embarked air group. Amidst endless media and online gibberish about “aircraft carriers with no aircraft” the UK is in fact, building up its fleet of F-35B Lightnings ready to go to sea. Here John Dunbar considers the concerns about the number of jets that will be available to form the Tailored Air Group, and how their efficiency might be maximised.

British F-35 numbers in service will be constrained, with around 48 front line aircraft in 4 squadrons, and a further 12 assigned to the Operational Conversion Unit (OCU). This suggests that around 16 jets will be routinely available for overseas or carrier deployment at any one time. (More could be embarked in emergencies, although achieving the theoretical maximum of 36 jets would be virtually impossible under existing plans.) The plan for the UK to buy 138 F-35s announced in SDSR 2015 sounds generous, but this figure is the total to be purchased over the entire lifetime of the aircraft (30 years?) and allows for replacement of older airframes.

Split buy. No thanks.

The RAF is arguing for a split purchase between F-35B and F-35A. Only the F-35B variant being purchased currently can operate from the carriers. This may appear superficially attractive and allow for a clear delineation between naval aircraft and land-based fleets. Unfortunately, a split fleet would add to logistic support costs (the different F-35 variants only have around 25% of components in common) and result in an even smaller pool of aircraft available to equip the aircraft carriers. A more detailed explanation of why the RN should resist this RAF proposal can be found here.

Sortie generation rate

Historically, a carrier’s ability to project power has been based on the number of aircraft that can be carried, which in turn determines the number of sorties that can be generated, and the air wings resilience to combat losses and battle damage.

Sustainable fast jet sortie generation rates have remained relatively static at 1 per day for ground-based aircraft and around 1.5 per day for carrier-based aircraft. There are number of factors which limit sortie generation rate – at any one time only 60-80% of aircraft will be available (due to the need for repairs or overhauls); flight checks and maintenance can limit the number of flight hours available to anywhere between 1 and 5 hours per day and pilot fatigue, mission briefing and debriefing can also limit how many missions can be undertaken in a 24 period. Based on current doctrine and taking these restrictions into account, 12 F-35s might be able to generate between 10 and 15 sorties per day.

US super carriers with 80 aircraft are theoretically capable of delivering around 120 sorties per day (or more than 200 in surge conditions) whilst the QEC are designed to develop a maximum of 120 sorties per day in total, of which at least 20 will need to be reserved for helicopter operations to support anti-submarine and airborne early warning operations. In practice, these maximum sortie rates are rarely achieved.

In operations over Libya in 2011 the French carrier Charles De Gaulle averaged 11 sorties per day. During operation Desert Storm, the USS Carl Vinson averaged 55 combat sorties per day.

However, future F-35 sortie rates need to be seen in the context of the step change delivered by 5th generation aircraft. The F-35’s stealth and complex digital architecture allow it to carry out some missions without supporting electronic warfare assets or the need for fighters to provide protection from opposing air forces. Where twelve aircraft were needed in the past, four F-35 can now accomplish the same mission and have better survival rates.

Whilst it may be too early to say that the F-35 is three times more effective than legacy aircraft, the clear implication is that far fewer sorties will be required to deliver the same impact in strike missions. Evidence of excellent air-to-air kill ratios emerging from Red Flag exercises also suggests that F-35 will be able to attain air superiority with fewer numbers than 4th generation aircraft.

Barring a long-term crisis, RN is not expected maintain continuous F-35 deployment. To keep a QEC carrier permanently at sea would require 3 or ideally 4 ships, although one will always be available for deployment at short notice. Instead, it is likely that each carrier will deploy for a total of nine months in any given 27 month period (meaning one of the two carriers will be at sea for 18 months out of 27). It is this deployment pattern that the RN and Joint Lightning Force will need to resource.

Silver linings

There are further reasons to be optimistic. Whilst the choice of F-35B has been over-criticised for its higher cost, more limited range and lower weapons load, it does bring with it the benefit of collaboration with the United States Marine Corps who intend to buy 340 F-35Bs.

The USMC is showing much greater commitment to the F-35B than the US Navy is to the F-35C, and are clearly determined to maximise its capabilities. In doing so, the USMC is updating its ‘Harrier Carrier’ concept to utilise amphibious assault vessels as small carriers deploying 15-20 F-35B.

Remarkably, the USMC has published plans for these platforms to deliver a sustained rate of up to 40 sorties in a 14 hour period across a range of combat operations – more than 3 sorties per day, per airframe. Whilst this does include utilisation of forward operating bases to maximise effectiveness, it still suggests that the USMC has found a way to shatter the 1.5 sortie rate per day ceiling, a doctrinal approach that the Royal Navy would benefit from evaluating.

The US Marine Corps is leading the way developing F-35B operating doctrine. They deployed 12 aircraft on USS America in November 2016 and now have 10 operational aircraft forward-deployed in Japan.

There are a number of reasons why F-35B sortie rates can be increased. The much-reduced workload associated with flying the aircraft and the quantum leap in situational awareness from the fused data and sensor technology could significantly reduce the time need for briefing and de-briefing. This reduces pilot fatigue to the point where two or more sorties per pilot, per day become achievable. The USMC has also focused intensively on ALIS (the Autonomic Logistic Information System) which plays a big role in maximising availability by managing and pre-empting fault detection and organising spares logistics. The Royal Navy’s close collaboration with USMC should make that learning available early in UK F-35 operations.

It is also now certain that USMC F-35 squadrons will operate from the RN’s carriers in coalition operations. Not only does this offer significantly increased fire power, but also opens up the possibility of in-flight refuelling from USMC V-22 Osprey, a capability the RN would dearly like to own itself at some point in the future.

Structuring the Lightning force

If the RN is going to work with the USMC in developing new operational doctrines, it follows that innovation in the F-35 force structure should also be considered.

The RAF has recently moved from 7 squadrons of 12 Typhoons to 8 Squadrons of 10 Typhoons, ostensibly because of improved availability of airframes, resulting from more effective maintenance. The Lightning fleet could follow suit, going from five squadrons of 12 F-35B to six squadrons of 10 F-35B. This could be undertaken in parallel with consideration of innovating the way in which the Operational Conversion Unit is supported.

Rather than having a squadron of aircraft dedicated to the OCU, 5 airframes each should be assigned (with maintenance crews) from 2 squadrons not scheduled for active deployment (preferably squadrons that have just returned from operations and who can feed learning into OCU development programmes). The aircraft remaining in each squadron will be more than adequate to meet weekly pilot flying hour requirements for the full complement of pilots, particularly given increased use and availability of simulators.

The Lightning fleet would then consist of 60 aircraft in 6 front line fighter squadrons (3 each for the RAF and Fleet Air Arm); with 10 UK based aircraft allocated to OCU duties. This can be achieved with the only additional cost being the extra pilots needed as instructors. That is a 25% increase in available combat aircraft derived from an additional 12-14 pilots needed for the OCU.

Lt Cdr. Ian Tidball, the first Royal Navy pilot to fly an F-35 in 2013. There will be a total of 26 RN and RAF pilots trained to fly the aircraft by the end of 2018.

This would also make a radical difference to RAF and RN flexibility in deployment without needing any extra aircraft in service. Rather than squabbling with the navy over the deployment of 16 aircraft, the RAF could be confident in being able to deploy 10 aircraft overseas at any one time, with 15 further aircraft available for UK based operations and training (excluding OCU). Acting in concert with Typhoon, small flights of F-35 can act as significant force multipliers – removing airframe competition for carrier use must be an attractive option to the RAF.

The Royal Navy could also be confident of having 15 F-35B as increasing deployment in increments of five aircraft up to an all-out effort of 30 F-35B embarked would be within the gift of the Fleet Air Arm as and when necessary. Alternatively, deploying with additional RAF or USMC F-35B in could enable a sustainable embarked air wing of 30 – 40 F-35B.

This more flexible structure would also start to allow distinctive doctrines to emerge, with the Royal Navy focusing on the high tempo expeditionary role modelled by the USMC, and the RAF focusing on longer duration deep strike missions supported by in-flight refuelling.


The F35-B is a revolutionary platform that invites further innovation to maximise its impact. A more flexible squadron structure alongside innovation in operational doctrine can help ensure that even with a modest air wing of 15 or 20 aircraft the Queen Elizabeth Carriers will pack a meaningful punch.



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