Source · Select Committees · Public Accounts Committee
51st Report - The UK’s F-35 stealth fighter capability
Public Accounts Committee
HC 1232
Published 31 October 2025
Recommendations
11
Deferred
Overall F-35 capability and availability remain inadequate, lacking standoff weapons and stealth assessment
Recommendation
Although the F-35 is significantly superior to any previous UK aircraft, the Department has yet to achieve the capability or availability that it wants.19 Most significant is the lack of the standoff weapon.20 This will limit the UK’s ability to …
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Government Response Summary
The government will set out its approach to delivering the Strategic Defence Review and the investments required to deliver the Integrated Force in the forthcoming Defence Investment Plan, including details on the standoff capability requirement.
HM Treasury
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13
Deferred
Department actively pursuing solutions to F-35 limitations, accelerating weapon integration and international assessment
Recommendation
The Department told us that it had plans to tackle these limitations. It is seeking opportunities within the global programme to accelerate the integration onto the F-35 of Spear 3 and Meteor, its preferred air to air weapon. The Joint …
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Government Response Summary
The government agrees with the Committee’s recommendation and states that the forthcoming Defence Investment Plan will set out the government’s approach to delivering the Strategic Defence Review (SDR) and the investments required to deliver the Integrated Force. This will provide details of the government’s balance of investment across the full range of military capabilities, including the capability requirement identified by the Committee.
HM Treasury
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18
Deferred
F-35 personnel at RAF Marham face unacceptable, low-quality accommodation and insufficient amenities
Recommendation
RAF Marham has been designated the F-35 main operating base since 2013 and now has at least 1,500 people working at the base to support the F-35 fleet, many of whom also live there.38 A 2025 NISTA programme review found …
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Government Response Summary
Following the publication of the Defence Investment Plan infrastructure requirements will be reassessed against departmental priorities. The department will write to the Committee by 31 May 2026 to advise whether the current timescale for RAF Marham accommodation can be brought forward.
HM Treasury
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21
Deferred
Accelerate the unacceptable 13-year accommodation upgrade programme at RAF Marham
Recommendation
The Department told us that it has plans to upgrade accommodation at RAF Marham but will not complete these plans for many years. The Department will upgrade 900 accommodation units and bedrooms across the base. However, the Department told us …
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Government Response Summary
The Department will reassess infrastructure requirements against departmental priorities following the publication of the Defence Investment Plan, and will advise the Committee by 31 May 2026 whether the timescale for RAF Marham accommodation can be brought forward.
HM Treasury
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Conclusions (10)
7
Conclusion
Deferred
The Department expects to declare Full Operating Capability (FOC) by the end of 2025. In its 2018 Concept of Use document the Department had expected to declare FOC by the end of 2023 based on two frontline squadrons of 12 aircraft and a training squadron at full capacity. It subsequently …
Government Response Summary
The government response is entirely unrelated to the recommendation regarding the F-35 Full Operating Capability (FOC) declaration, instead discussing the 'illegal meat crisis' and biosecurity at the border.
8
Conclusion
Deferred
The Department told us that its criteria for declaring FOC are based on a combination of hard facts and applied military judgement. In forming its view, it told us that it had considered FOC through four distinct 5 C&AG’s Report, para 9 6 Q 91 7 C&AG’s Report, para 1.19 …
Government Response Summary
The government response is entirely unrelated to the recommendation regarding the F-35 Full Operating Capability (FOC) criteria, instead discussing animal vaccine availability and ongoing cross-sector engagement, with an action plan to be published in late 2026.
9
Conclusion
Deferred
The Department acknowledged that its definition of FOC excludes a crucial element of capability. It does not include a requirement to integrate Spear 3 onto the F-35 to provide a standoff weapon to attack ground targets from a safe distance, which it does not expect to have until the early …
Government Response Summary
The government response is entirely unrelated to the recommendation regarding the F-35 FOC definition, Spear 3 integration, or personnel shortages, instead discussing Sanitary and Phytosanitary (SPS) agreements with the EU and strengthening resilience to animal disease.
12
Conclusion
Deferred
The Department set out why these capability limitations have occurred. It told us that its ability to integrate new weapons was dependent on the global F-35 programme run by the United States Department of Defense. It requires the major software enhancements provided by Tech Refresh 3 and Block 4, which …
Government Response Summary
The government will set out its approach to delivering the Strategic Defence Review and the investments required to deliver the Integrated Force in the forthcoming Defence Investment Plan, including details on the standoff capability requirement.
19
Conclusion
Deferred
The Department accepted that accommodation at RAF Marham is not good enough, reflecting wider problems within the Defence estate, more than half of which is over 50 years old. The Department told us that it had identified the need for increased investment in accommodation in the Strategic Defence Review and …
Government Response Summary
The government agrees with the recommendation, but will reassess infrastructure requirements against departmental priorities following the publication of the Defence Investment Plan and will advise the Committee by 31 May 2026 whether the current timescale for RAF Marham accommodation can be brought forward.
20
Conclusion
Deferred
The Department acknowledged that providing poor quality accommodation negatively impacts its personnel. Most significantly, it increases the risk that people leave the service earlier than they otherwise would.41 This is a serious risk given the problems with retention that the Department has set out and the length of time it …
Government Response Summary
The government agrees with the recommendation, but will reassess infrastructure requirements against departmental priorities following the publication of the Defence Investment Plan and will advise the Committee by 31 May 2026 whether the current timescale for RAF Marham accommodation can be brought forward.
22
Conclusion
Deferred
The Department acknowledged that it has, on occasion, prioritised short-term affordability over value for money in the F-35 programme, to keep within its overall departmental budget.46 Notably, in 2021 the Department took the decision to delay investment in the Air Signature Assessment Facility (ASAF). Although this decision saved £82 million …
Government Response Summary
The government agrees with the Committee’s recommendation and states that as part of the production of the forthcoming Defence Investment Plan, the government is considering the long-term impacts of any savings measures on costs and capability of all major programmes.
23
Conclusion
Deferred
In correspondence provided after our evidence session the Department told us that 809 Naval Air Squadron’s infrastructure is another example of short-term savings resulting in higher overall costs. In 2020 the Department forecast that the cost of building the infrastructure would be around £56 million and be completed in 2023. …
Government Response Summary
The government agrees with the Committee’s recommendation and states that as part of the production of the forthcoming Defence Investment Plan, the government is considering the long-term impacts of any savings measures on costs and capability of all major programmes.
24
Conclusion
Deferred
The Department also acknowledged that short-term savings impact the capability provided by the programme. The ASAF, which measures the stealth characteristics of the UK F-35 fleet, is needed for the Department’s freedom of action policy so that it can deploy the aircraft at any time or place of its choosing.49 …
Government Response Summary
The government agrees with the Committee’s recommendation and states that as part of the production of the forthcoming Defence Investment Plan, the government is considering the long-term impacts of any savings measures on costs and capability of all major programmes.
25
Conclusion
Deferred
The Department told us that in 2010, facing a reduction in its budget, it chose to delay the delivery of some aircraft.52 This has reduced the number of aircraft available to the Department today.53 This was exacerbated by a further delay of seven aircraft by a year in 2020 for …
Government Response Summary
The government is considering the long-term impacts of savings measures on costs and capability of all major programmes as part of the production of the forthcoming Defence Investment Plan.