US Marine Fighter Attack Squadron 121, which began flying its F-35B jets to the air station in January, now has a full complement of 16 aircraft.

The squadron — which five years ago became the first in the US Marine Corps to receive the jets — also became the first forward-deployed F-35 squadron when it moved to Iwakuni from US Marine Corps Air Station Yuma.

This comes as the 13th F-35B for the United Kingdom was recently delivered by Lockheed Martin.

It is believed that 138 F-35 aircraft will have been delivered by the 2030s. Around 2023, the Ministry of Defence have indicated that the UK will have 42 F-35 aircraft with 24 available as ‘front-line fighters’ and the remaining 18 will be used for training (at least 4-5 on the OCU), be in reserve or in maintenance.

Numbers right now are exactly where they’re expected to be and inline with the 2015 Strategic Defence and Security Review.

2 F-35B in LRIP run 3, 1 F-35B in LRIP run 4, 1 F-35B in LRIP run 7, 4 F-35B in LRIP run 8, 6 F-35B in LRIP run 9, 3 F-35B in LRIP run 10, 2 F-35B in LRIP run 11, 2 F-35B in LRIP run 12 6 F-35B in LRIP run 13, 8 F-35B in LRIP run 14 and 7 F-35B in LRIP run 15. This brings us to 42 in 2023.

The next year and next run brings us to the total of the first batch of aircraft, 48.

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16 is for me the optimal size of a squadron as it gives 4 flights of 4 with the ability to have a self sustaining unit that can ensure a minimum of 8 airframes are available at any point in time. For the carriers 2 Sqdn of 16 is optimal – not the 24 that HMG would like us to believe. Put simply there would be 4 aircraft at immediate readiness, 4 at high readiness/training, 4 in std maintenance and 4 in deep maintenance. Not sure how many aircraft are available out of an RAF sqdn of 12 at any… Read more »


Once again the USMC leads the way both in kit, organisation and operational effectiveness.


‘maintenance’ to be covered by the ‘remaining 18’ according to this article and earlier releases. I assume that does mean ‘Deep maintenance’ with airframes rolling into the 12 as other aurframes role out of the 12 .

Mr Bell

These are new aircraft. Not sure how much deep maintenance they will need initially. Other threads on this site indicate the F35 airframe is very tough and has withstood extensive continuous testing. My biggest concern is the RAF putting a deliberate stumbling block into the RN and carrier operations by demanding a switch to the A variant of the F35 when we should be keeping the faith and continue as planned. optimal numbers should be 96 F35Bs in active service so that we can operate both carriers if needed at a surge capacity of 36-48 aircraft. if RAF gets its… Read more »

Mike Saul

The RAF doesn’t need the B variant, the A is cheaper to buy and maintain plus you need 50% fewer A’s to complete many combat missions than a B (that’s munitions on enemy targets).

The economics and military effectiveness of buying a mix of A and B variants far out weigh the arguement that we have purchased two large carriers and need to buy aircraft to fill them up.


Agreed that they are new and deep maintenance should not be required, but organisationally the Air force (and navy and army) should be prepared to rotate its assets (which includes people) through different levels of readiness. My view is that this will not only be cost efficient but will ensure retention of service as forces personnel can plan their family life better. A period of deep maintenance would align with non deployed duties, training and return to family as often as possible and if cycled accordingly this would mean that people spend at least 1 Xmas away from home in… Read more »

Alan Reid

Hi Mister B, Beyond the requirement for 48 aircraft; other than perhaps to top-up for attrition, I see no great reason for the UK to invest further in the F-35B version; no doubt, it’s a superb aircraft – but it’s STOVL flexibility does come at the cost of some performance penalties, particularly in range. The “big-wing” A version is a much better fit for operations in which the RAF is likely to be involved. (Moving forward, you can also see a scenario developing where the FAA will take over all the STOVL aircraft). I’m a big fan of our new… Read more »


Whilst accepting that the A variant is indeed the best I think the RAF have typhoon to provide the legs and reach that you are talking about and I do believe we need to standardise our fleet as much as possible. If we replace our Typhoons with F35A’s then I am fine with that, but given our relatively small fleet size (138 total against a 400+ operational fleet for the USMC alone) then I can’t see the sense in purchasing another variant, its just a level of complexity that is not needed unless the numbers go up (which they won’t).… Read more »

andy reeves

how is it that the u.k ,the only level 1 partner in the f 35, programme has to wait while the f 35b is given to japan before us? is the u.k asking why? i doubt it aircraft carriers with no aircraft , the t 26 beginning 5 years later than planned, the type 31 being designed on the back of a fag packet, plus the ocean, supposedly surplus and being sold, is on duty as a FLAGship on a nato exercise.oh i nearly forgot a 6 ship class of the worlds leading class of destroyer breaking down all over… Read more »

Mike Saul

The aircraft may be physically tough, but the software needs constant updating and maintenance.

It’s that software that makes the F35 the fantastic aircraft it is, but that advantage comes at a cost in terms of availability of aircraft when the aircraft is relatively immature in software terms.

andy reeves

but the united states of paranoia don’t trust its biggest customer with it because we can’t be trusted. the u.k still has time to cancel the f 35 order rafaels and gripens are built in half the time of a f 35 cancel 2 f 35’s to fund CATOBAR on the carriers.this would save hundreds of millions of£ and give america a well overdue middle finger. but lets face it the u.k doesn’t have the balls to do it.

Lee H

Morning all To sustain carrier operations the U.K. needs a minimum of 4 F-35B Sqns (12 a/c). This means just over 100 a/c will be required. Of all the variants of F-35 the B model is the most complex and therefore most expensive per platform. Cost however should be measured in overall capability. Our CVF platform cost ROM £3bn each and for that we get a carrier that if required could happily host 36 F-35B. US Ford carrier at over $10bn is somewhat out of our reach but it provides the US a platform where they can launch slightly cheaper… Read more »


Couldn’t agree more with you Lee and I will go further. We should really be ordering 300 F35b’s as realistically there is nothing else out there that is as good for the next 20 years. I do have a bit of an issue with people accepting tactical capability gaps and then being unwilling to pay the cost of regeneration. If we are getting rid of something totally then that needs to be said up front. An F35 order of the magnitude of 300 will pay for itself over the next 25 years and by standardising on a single platform (albeit… Read more »

Lee H

Hi Pacman27

Basic fleet management set against a defined set of strategic goals – used by successful multi-national companies all over the world.
Unfortunately this is government we are talking about here. They have no vision, therefore lacking the definition of a mission so therefore executing low level tactical options satisfying industry needs and sustaining their seats in Parliament.
May have sounded a bit negative there…..


Sadly I agree with you and it is one of the primary reasons why we spend more on maintenance than equipment. Time to change that and god knows the industrial base could do with the orders. We need to commit to a set of basic numbers of everything each year and just build. 1 Escort (T31) 0.5 Escort (T26) 0.5 Submarine 0.75 Fleet Aux (inc amphibious) 6 – Fighters (F35A) = 150 Total Order/Fleet 6 – Fighters (F35B) = 150 Total Order/Fleet 12 – UAV (Taranis) = 300 Total Order/ Fleet 1 – Transport = 25 Total Order 1 –… Read more »