A letter from the Minister of State for Defence Procurement sets out the status of the UK’s F-35 fleet.

The letter from James Cartlidge MP, Minister of State for Defence Procurement, to Jeremy Quin MP, Chair of the House of Commons Defence Committee, covers several key points regarding the development and operational status of the UK’s F-35 Lightning Force.

Here’s a summary.

  • Full Operating Capability (FOC) Declaration: The FOC for the first phase of procurement (Tranche 1) is set for no later than 31st December 2025, with 33 out of the first 48 aircraft already delivered.
  • Squadron Developments: The second front line squadron, 809 Naval Air Squadron, was recommissioned at RAF Marham on 8th December 2023 and is working towards its Initial Operating Capability scheduled for 1st December 2024. The squadron, like the rest of the Force, will be jointly operated by the Royal Air Force (RAF) and Royal Navy (RN).
  • Operational Contributions: The Lightning Force continues to support NATO, particularly in response to Russia’s actions in Ukraine, with UK F-35Bs undertaking long-range missions and integrating with other partner nations’ forces. Operation FIREDRAKE in 2023 highlighted the F-35Bs’ capabilities through various tasks and exercises aboard HMS QUEEN ELIZABETH, showcasing interoperability with other nations.
  • Developmental Testing: A period of testing was conducted in October 2023 aboard HMS PRINCE OF WALES to expand the operating envelope for F-35B aircraft on UK Queen Elizabeth Class Carriers, aiming to formally approve expanded operating limits and procedures.
  • Costs: Despite global inflation and foreign exchange challenges, the initial procurement remains within budget, with a notable decrease in aircraft price from 2014 to 2022, albeit with an expected slight increase for upcoming lots due to inflationary pressures.
  • Capability Milestone Timeline Progress: The letter highlights the growth and maturation of the Force, including recruitment and training efforts for engineers, pilots, and instructors. However, it notes a temporary delay in aircraft deliveries due to software instability with Lockheed Martin’s Technical Refresh 3, which is not expected to impact the FOC declaration.
  • Future Developments: Discussions are underway for the procurement of an additional 27 F-35 aircraft in Tranche 2, aimed at enhancing the UK’s Carrier Enabled Power Projection capability and increasing the fleet to 74 aircraft by 2033, with funding for this phase secured under an approved option.

Here’s the letter in full.


Dear Jeremy,

I am providing an update on the continuing growth and capability delivery of the F-35 Lightning Force. Since I wrote to your predecessor in July 2023, the declaration of Full Operating Capability (FOC) for the first procurement phase (Tranche 1) has been agreed as occurring no later than 31 Dec 2025. The first 48 aircraft continue to be produced as scheduled, with 33 aircraft received to date. The second front line squadron (809 Naval Air Squadron) was stood up in a re-commissioning ceremony at RAF Marham on the 8th December 2023. 809NAS will continue to work-up readiness throughout 2024, ahead of its Initial Operating Capability scheduled for 1 Dec 2024. As across the Force, 809NAS will be jointly operated by the RAF and RN.


The Lightning Force continue to provide a key component of the UK contribution to NATO in response to Russia’s continued illegal war and occupation of Ukraine. In 2023 UK F-35Bs have undertaken long-range missions from RAF Marham; supported by Voyager tankers, seamlessly integrating with our own 4th Generation Typhoon, and fighters from other partner nations, to form a potent force mix.

Carrier Strike 2023, Operation FIREDRAKE, was undertaken between 11 September and 10 November 2023; eight aircraft, pilots and supporting personnel boarded HMS QUEEN ELIZABETH and undertook a range of operational tasks, joint exercises, and Defence engagement with other nations. Initially, they engaged in Joint Expedition Force (JEF) activities, working with Norway, Sweden and Finland, after which they undertook Large Force Employment activity with the Royal Netherlands Air Force. The final element of the deployment was under NATO direction, where NATO interoperability was demonstrated alongside Estonian, Latvian and Polish military forces.

In our last report we advised that a period of developmental testing using Joint Program Office (JPO) Integrated Test Force F-35Bs on HMS PRINCE OF WALES had been deferred to autumn 2023, following HMS PRINCE OF WALES serviceability issues. This period of testing successfully took place in October 2023 with the intent to expand the embarked operating envelope for all F-35B aircraft onboard UK Queen Elizabeth Class Carriers and Shipborne Rolling Vertical Landings for the platform; the trials have formed the evidence base towards formal approval aimed to expand operating limits and authorise those procedures in an updated Royal Navy, Ship Air – Release.

Programme Costs

Initial procurement (Tranche 1) expenditure has remained within its cost approval envelope, with almost all funds committed. Global inflation and foreign exchange currency (FOREX) challenges have been the key themes of the previous 18 months. The aircraft price has reduced by 32% over the period 2014 to 2022. However, it is anticipated that the price of each aircraft in LOTs 15-17 will increase marginally by around 6%. This is predominately due to increasing manufacturing costs associated with inflationary pressures. Inflation and FOREX continue to be a concern to the Programme, as do the recent savings pressures levied across the department.

Capability Milestone Timeline Progress

Following the successful stand up of 809NAS in December 2023, Force growth will continue to mature and build our frontline squadrons’ capabilities out to December 2025. Force growth remains an actively managed issue. We have already implemented the first increased recruitment of the required engineering workforce across the RN and RAF. The Operational Conversion Unit continues to graduate F-35B pilots into the Force at a sufficient rate. Additionally, the Force has trained a new tactical weapons instructor and 6 flying instructors, which has provided additional instructor depth. However, Lockheed Martin has currently suspended aircraft release post-production as they have experienced software instability during developmental testing of Technical Refresh 3, the next pan-platform software upgrade. We are aware of the current short-term delays to UK aircraft deliveries. At this time, it is not assessed to impact the scheduled FOC declaration at the end of 2025.

Beyond FOC, deliveries of ‘Tranche 2’ will start and the next significant operational capability development will occur towards the end of the decade, with UK weapons

(METEOR and SPEAR 3) being fielded on the UK’s front-line. UK and JPO negotiations regarding the ‘Tranche 2’ buy of a further 27 F-35 aircraft are going well. This next procurement phase is expected to complete the internal approvals process during summer 2024. It will realise our long-term ambition to deepen Carrier Enabled Power Projection capability and will bring the UK fleet up to 74 aircraft, allowing us to create a third front line squadron by 2033. Funding for this next phase has been ringfenced under an approved ABC Option.”

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George has a degree in Cyber Security from Glasgow Caledonian University and has a keen interest in naval and cyber security matters and has appeared on national radio and television to discuss current events. George is on Twitter at @geoallison
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Mr Bell
Mr Bell (@guest_821076)
1 month ago

If you hoped for the next batch of F35Bs to be brought into service relatively quickly. You’ll be disappointed. We’ve continued the anaemic purchasing rate as we obviously as a nation cannot truly afford to correct equip and arm ourselves.
2033 is a decade away. That is a long long time to deliver just 27 aircraft.
There is a complete disconnect between the deteriorating international security picture, increasing threats and dear old Tory HMGs response.

Jonathan (@guest_821090)
1 month ago
Reply to  Mr Bell

But what is worse is they are spouting off about a pre war world and only they can be depended on to secure the nation….it’s so awful.

Spyinthesky (@guest_821131)
1 month ago
Reply to  Mr Bell

Lockheed Martin has currently suspended aircraft release post-production as they have experienced software instability during developmental testing of Technical Refresh 3, the next pan-platform software upgrade.’

The above deeply concerns me as it suggests that despite reassurances from LM that the problems with Refresh 3 that is vital to properly arming our F-35s and making them truly effective. Endless delays it seems with no end in sight.

Spyinthesky (@guest_821154)
1 month ago
Reply to  Spyinthesky

Sorry after ‘effective’ I meant to add ‘continue’.

Marked (@guest_821145)
1 month ago
Reply to  Mr Bell

It’s pointless rushing the buy when they will all be handicapped by a woefully insufficient weapons load out. We might as well wait until they can use the weapons they need and save a fortune in upgrade costs.

FieldLander (@guest_821183)
1 month ago
Reply to  Mr Bell

Not sure that ‘dear old Tory HMGs response’ is going to be remotely relevant.

Martin (@guest_821079)
1 month ago

By the time we get all F35 the oldest ones will be 15/20 years old, the production rate is rubbish, too many sold but not built across the world and software up dates are already an issue as the USA controls them and they are delayed.
Bad choice getting some few so slow. Held to ransom by are the US again.

Andrew D
Andrew D (@guest_821084)
1 month ago
Reply to  Martin

That’s a so called special Relationship for you Martin 😟

Martin (@guest_821087)
1 month ago
Reply to  Andrew D

one sided, as always they just use us to justify wars etc. I do not trust them they desert every friend when it suits them, Korea/Vietnam/Afghan’s etc etc

Jonathan (@guest_821091)
1 month ago
Reply to  Martin

To be far it’s not just the US, there is no morality in geopolitics..nations are not moral they simply exist to self perpetuate and protect themselves..nothing more nothing less..alliances are simply an expression of enlightened self interest nothing more nothing less…

Its one of the key reasons every nation in NATO should be ensuring their own defence…and why the UK needs to keep its own nuclear deterrent…if anyone thinks the modern U.S. would trigger MAD for a European nation they are a bit naive.

Paul (@guest_821188)
1 month ago
Reply to  Martin

Things are tough all over, US F-35s are also “held to ransom” by TR-3 and Block 4 timelines. The best, longest range strike weapons available for USN F-35Cs is the unpowered JSOW with a max range of 70 nm. The newer weapons like LRASM can only be used by Super Hornets so far. Weapon integration delays are frustrating for everybody, USA included.

Martin (@guest_821211)
1 month ago
Reply to  Paul

the F35 is a very troubled item, some would say over priced and made at such a low rate to keep the price up etc.

Brom (@guest_821085)
1 month ago

Problem is the yanks are trying to make it as difficult as possible for owners of the aircraft to use their own technology and weapons to try and force them to ‘buy American’

Unless you’re Israeli that is…..

Martin (@guest_821088)
1 month ago
Reply to  Brom

i do not trust them,

Jonathan (@guest_821089)
1 month ago

So we will have the first batch of deliveries finished by 2025…but it’s then going to take 8 years to deliver a further 27 aircraft….that’s 3-4 per year…considering the 27-30 timeline for likely war that’s pathetic….

Im sorry but we sit and listen to the Secretary of State for defence telling us we are in a pre war state heading for essentially world war 3..on the same day as the Primeminister is telling the country only he can guard the nation….all the while not even finalising an order for F35 in a timely way…

Peter S
Peter S (@guest_821112)
1 month ago

What a good thing that in 1938 we didn’t announce a plan to buy some more Spitfires by 1947.
With Tech refresh 3 hitting so many problems that the US is refusing to accept new deliveries and aircraft are parked at LM, it isn’t entirely fair to blame the UK government for the slow acquisition schedule. Current aircraft cannot do what we want- operate Meteor and Spear 3. It would be better to order additional Typhoons that can operate the weapons we want to deploy.

ChariotRider (@guest_821148)
1 month ago
Reply to  Peter S

Sadly, ordering more Typhoons is looking increasingly like a good option, although it won’t help the carrier strike capability. Instead, ordering more Typhoons that we know, or believe, work well would hedge against similar delays in the Tempest program. I’m kinda hoping that they don’t try to be too clever on Tempest and instead build on our experience with Typhoon and F35, i.e. get the basics right first and then spiral develop the capabilities over time. We need something that works, can deliver a modern basic range of capabilities which, these days, includes Meteor and SPEAR 3 from the start,… Read more »

ABCRodney (@guest_821113)
1 month ago

After decades of trying to de cypher or understand the wormy language used by Politicians I’m slight concerned about what the last sentence means.

“Funding for the next phase of procurement has been ringfenced under an ABC option” ???

Can anyone who has ever worked in MOD procurement enlighten me ?

In plain English what is he on about ?

Dragonwight (@guest_821128)
1 month ago
Reply to  ABCRodney

Annual budget cycle, I believe. So they don’t need to ask for more money, it’s already allocated and ring fenced under the annual budget. That’s how I read it.

Last edited 1 month ago by Dragonwight
BobA (@guest_821144)
1 month ago
Reply to  Dragonwight

That’s exactly what it means. It’s already approved in the budget and it’s ring-fenced – ie it’s specifically for that purpose, not to be redistributed. It’s a good thing

Joe16 (@guest_821119)
1 month ago

The biggest concern to me is how long it’ll take to get Block IV capability into the fleet- 5.5 years from now…
I know TR-3 is supposed to be approved this year, which is a pre-requisite for the Block IV software. But if that’s how long they reckon the engine upgrades to take as well then I think we should be talking to the JPO about getting Meteor and Spear integration early- neither of which are really reliant on Block IV as such, unless I’m mistaken?

Rudeboy (@guest_821182)
1 month ago
Reply to  Joe16

Realisitically our first Meteor capable squadron will not be in place until 2030. And the aircraft will be new production from the 27 in phase 2. With a following wind we could get the entire operational fleet of 70/71 aircraft to Block IV Lot 19 standard by 2033…10 years from now.

Joe16 (@guest_821186)
1 month ago
Reply to  Rudeboy

Sure, if we kept it as a Block IV capability.
But, given the delays incurred by the project team, can’t the UK wrangle to have that as a Block 3F (I think we’re on F?) capability and start integrating now? It’s their fault it’s delayed, so they should be working to give us the capability sooner as a customer. As far as I’m aware, if the current software can support AMRAAM and JDAM/Paveway, it can support Meteor and Spear.

Pete (@guest_821129)
1 month ago

Can FOC really be declared ( and I know it can) when the principle weapon capabiltes long intended for the f35b won’t materialise until 2030 when the ability to prosecute SPEAR cap 3 and Meteor capabilities may finally be achieved ( a couple of decades after the contractual process to develop design criteria for integration into the F35b commenced with SPEAR 3 in 2011 and Meteor F35b integration contract work commenced in 2017)

John Clark
John Clark (@guest_821133)
1 month ago

Totally irrelevant, I wish they would all just shut up. All current government ministers should start to concentrate on clearing their offices and getting ready to ‘spend more time with the family’. Anything they say or promise has a 6 week shelf life and counting down, they may as well promise a British military base at the top of mount Everest or on the moon by 2033, it’s all utterly pointless water treading spin and hot air… We all need to concentrate on Labours defence position now and hypothesise regarding their SDSR2025 position. That’s the relevant viewpoint looking forward, the… Read more »

Last edited 1 month ago by John Clark
Deep32 (@guest_821143)
1 month ago
Reply to  John Clark

You may well be correct in that we need to concentrate on Labours defence position, if only we actually knew what it was in its entirety, other than ditching our current commitment to ‘global Britain and the tilt East’ that is.
Waiting for yet another SDSR sometime in 2025 is not actually the answer, as we already know what the world looks like and whats needed.

John Clark
John Clark (@guest_821153)
1 month ago
Reply to  Deep32

Totally agree that waiting for SDSR25 isn’t the answer mate, but non the less, nothing will happen because Starmer can happily kick it into the long grass until then, with a lot of spin bullshit….

DaveyB. (@guest_821251)
1 month ago
Reply to  Deep32

As much as Labour would like to kick the tilt east into touch. I think they will be hamstrung by the AUKUS agreements. Personally, I don’t think very much will change. They won’t have the budget to do the big ticket ideas. There is very little left to cut from the services to generate funds. Plus Ukraine and Putin are now in the public mind. The great unwashed are now becoming aware of how tiny our forces have become. They are now looking past the window dressing and starting to ask questions.

Henry Lamb
Henry Lamb (@guest_821138)
1 month ago

2033?? That is truly pathetic. How old will the F35 program be by then and what capability gap is that leaving in the interim when actually needed. The carriers themselves will be 15/16 years years old by 2033. Better hope for a massive leap forward in drone procurement in that time to bolster numbers and even that looks uncertain.

Jonno (@guest_821570)
1 month ago
Reply to  Henry Lamb

The carriers will still be in virtually unused condition by 2033. Unlike the US carriers which spend inordinate time on station ours have a very low mileage and should easily last 50 years.

I think the days of manned combat planes is nearing its end in the front line and unmanned F35’s is an option, with loyal wingman drones. Makes sense to continue buying at whatever rate we can afford.

Continue with a joint force or you p..s off the RAF who do know about allair and continuing a gradual merger of sorts would seem sensible.

Rfn_Weston (@guest_821142)
1 month ago

At this point I’d be genuinely considering calling it complete at 48, getting them delivered ASAP, and allocating them all fully to the Navy.

Give RAF more Typhoons where we can do what we want development wise.

Shit show as usual.

Roll on Tempest. Fingers crossed.

Katmandoo (@guest_821179)
1 month ago

So 9 years to wait, for 27 aircraft… Really?

Andrew (@guest_823763)
1 month ago

This is why the early retirement of the Harriers was such a mistake. They should have been retired on a 1 F35 in 1 Harrier out basis.