F-35 Programme Faces Delays In UK

Britain’s £71bn stealth jet programme in crisis as watchdog reveals serious flaws

A damning report by the nation's spending overseer has revealed a catalogue of critical issues undermining the UK’s premier aerial combat initiative. The National Audit Office (NAO) found that serious delays, chronic personnel shortages, and major infrastructure gaps are severely hampering Britain’s combat readiness. The inquiry into the F-35 stealth jet programme paints a grim picture of a project struggling to deliver on its promises. While the Ministry of Defence (MoD) insists the programme remains within budget, the NAO’s findings question the value returned from the billions of pounds already spent. The watchdog warns that the combat readiness of this cutting-edge fleet is far below the levels the military requires to face emerging global threats. The situation casts a long shadow over the future of UK air power and its role on the world stage.

The promise of a fifth-generation fighter

The F-35 Lightning jet, produced by the United States corporation Lockheed Martin, represents a generational leap in air combat technology. Its design incorporates stealth characteristics, allowing it to evade sophisticated enemy radar systems. The aircraft boasts an advanced suite of integrated sensors. These systems gather and fuse data from the surrounding environment, providing the pilot with unparalleled situational awareness. This information is displayed on a state-of-the-art helmet interface, turning the pilot into a strategic manager of the battlespace. The MoD considers the jet to have capabilities far beyond any previous aircraft in the Royal Air Force (RAF) or Royal Navy fleet. Its introduction was meant to provide the UK with a decisive technological edge for decades, with the aircraft having a planned service life extending to 2069.

An ‘underwhelming result’ on investment

Despite the aircraft’s potential, the NAO delivered a blunt assessment of the programme’s progress. The watchdog described the capabilities achieved from the £11 billion expenditure to date as an "underwhelming result" for the taxpayer. This initial investment phase has been beset by problems that have prevented the military from fully realising the advantages of the new platform. The expenditure, already greater than the first projections from 2013, has failed to produce a consistently ready and available fighting force. The report suggests a fundamental disconnect between the significant financial outlay and the actual combat power currently available to commanders. This financial disappointment forms the foundation of the broader critique of the programme’s management and strategic oversight by the MoD.

Spiralling costs and disputed figures

The financial concerns extend far beyond the money already spent. The NAO has sharply contested the MoD’s official forecast for the total cost of the F-35 programme. The MoD was compelled to provide an estimate of £57bn for acquiring and maintaining a full fleet of 138 jets through to 2069. However, the NAO report argues this figure is a significant underestimate. The watchdog’s own projection places the whole-life cost at a staggering £71bn. Auditors noted that the MoD’s lower figure critically omits essential support costs, including fuel, infrastructure, and the billions needed for advanced weapons systems. This vast discrepancy in financial projections raises serious questions about transparency and the long-term affordability of the UK’s stated ambition.

The persistent problem of availability

A central and alarming finding from the NAO’s inquiry concerns the fleet’s operational readiness. An aircraft’s availability is the single most important metric of its usefulness. The report reveals that the F-35 fleet is consistently failing to meet the MoD’s own availability targets. These targets, the report notes, are already "significantly" less ambitious than the global targets for the F-35B model, which is also operated by the US Marine Corps. The persistent inability to get these highly advanced jets ready for missions points to deep-seated issues within the support structure of the programme. It suggests the UK is struggling to manage the complex logistics and maintenance that the fifth-generation fighter demands.

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Readiness rates fall drastically short

The specific figures on aircraft availability are stark. The NAO found that the fleet's capacity to handle all its core duties, its 'full mission capable rate', hovered at just a third of the Ministry of Defence's goal. This metric is a key measure of the jet's ability to perform. A second, less demanding measure, the "mission capable rate," assesses if the jet can perform at least one of its seven primary tasks. On this count, the fleet achieved only about half of the MoD’s target. These statistics indicate that on any given day, a large portion of Britain’s multi-billion-pound stealth jet fleet is not fully prepared for combat. This performance falls well below the standard required for a frontline asset.

Engineers and spares in short supply

The investigation identified two primary causes for the poor availability rates. The UK is suffering from a major shortage of qualified F-35 engineers, a problem compounded by a global scarcity of spare parts for the aircraft. The complexity of the F-35’s systems requires highly specialised training for maintenance crews, and the MoD has failed to build a large enough pool of this talent. Simultaneously, the global demand for F-35 components outstrips supply, creating long waits for crucial parts. This dual bottleneck means that when aircraft require repairs or routine servicing, they remain grounded for extended periods, directly impacting the number of jets prepared for service at any one time.

Corrosion creates unexpected challenges

Adding to the maintenance difficulties, the report highlighted the unexpected impact of naval operations on the aircraft. The F-35B variant, designed for short take-offs and vertical landings, is the cornerstone of the UK’s carrier strike capability. It operates from the decks of the Royal Navy’s two large aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales. However, the harsh maritime environment has resulted in unexpectedly high levels of corrosion on the aircraft. This problem adds another layer of complexity to the maintenance workload, requiring more frequent and intensive servicing to keep the jets in fighting condition. The issue demonstrates a potential underestimation of the challenges of operating this advanced technology at sea.

A fleet grounded by maintenance

The chronic maintenance issues reached a critical point between October 2024 and January 2025. During this four-month period, a startling revelation in the NAO inquiry showed that at times, no F-35 jets were available to perform any missions whatsoever. The entire fleet was undergoing various stages of maintenance, leaving the UK without one of its primary offensive air assets. While the MoD managed to improve availability rates temporarily for a subsequent deployment aboard HMS Prince of Wales, the NAO expressed doubt that this higher level of readiness could be sustained. This period of zero availability serves as a stark illustration of the fragility of the current support system for the F-35 fleet.

Delayed timelines for full strength

The programme’s schedule has suffered significant setbacks. A declaration of Full Operating Capability for the F-35 force is now expected by the close of 2025. This milestone marks the point at which the force is considered fully ready for sustained, high-intensity operations. The new date represents a two-year delay from the original plan set out in 2018. The delivery of the first full batch of 48 aircraft is also behind schedule, with the final jet from this order now expected to arrive in April 2026, not before 2024 concludes as planned. These delays postpone the point at which the UK can field a credible, carrier-borne stealth fighter force, creating a capability gap in national defence.

Weapons systems on the waiting list

A fighter jet is only as good as the weapons it carries, and here the F-35 programme faces one of its most critical delays. The integration of key missile systems has been pushed back to the beginning of the 2030s. This affects the MBDA SPEAR 3, a sophisticated air-to-ground missile designed to strike objectives from a protected distance. It also impacts the Meteor beyond-visual-range air-to-air missile, which is essential for air superiority. The NAO report states that the original in-service date for these crucial weapons was December 2024. The delay is blamed on poor supplier performance and commercial arrangements that failed to prioritise the UK’s needs within the global programme.

A toothless tiger in the short term

The consequence of the weapons delay is severe. Without the SPEAR 3 missile, the F-35’s capacity for striking ground-based objectives while remaining outside the reach of enemy air defences is limited. This blunts its effectiveness in the strike role it is intended to perform. Similarly, the absence of the Meteor missile restricts its dominance in air-to-air combat against other advanced fighters. Until these weapons are fully integrated, the UK's F-35 fleet cannot deliver its full warfighting potential. The aircraft can fly, but its offensive power remains significantly constrained, limiting the strategic options available to the government and military commanders for the remainder of this decade.

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The challenge of recruiting and retention

The shortage of skilled personnel extends beyond the engineering corps. The NAO report highlights "major personnel shortages across a range of roles" that are unlikely to be resolved for several years. The Lightning Force requires not only pilots but also a deep support structure of intelligence analysts, mission planners, and cyber specialists. The MoD is competing with the private sector for many of these highly skilled individuals. The failure to recruit and retain enough people is a fundamental threat to the programme’s success. An aircraft as complex as the F-35 is a system of systems, and the human element is as vital as the hardware.

MoD underestimated support needs

The personnel crisis stems from a significant planning failure. According to the report, the MoD previously underestimated the number of engineers and other support staff required to operate the F-35 effectively. This miscalculation has led to the current situation, where there are not enough trained people to maintain the aircraft, plan missions, and support deployments. The MoD is now actively recruiting to fill the gaps, but training new personnel for these specialised roles takes years. This legacy of underestimation means the force will likely be operating under considerable strain for the foreseeable future, directly impacting its ability to generate ready aircraft and conduct complex operations.

The UK’s place in the global programme

Britain holds a unique position as the only Tier 1 partner in the US-led F-35 global programme, a status earned through a significant early investment in its development. This position grants the UK influence over the project’s future and substantial work for British defence companies. However, the NAO warns that this privileged status could be at risk. The report reveals that officials within the F-35 programme are concerned that the slow pace of purchasing the full complement of 138 jets could "jeopardise the UK's position." Influence within the vast international consortium is tied to the level of commitment, and wavering on the final fleet size could diminish the UK’s voice.

Allies note the slow pace of acquisition

The UK's hesitation has not gone unnoticed by other partner nations. The NAO inquiry points out that Britain's tardiness in placing further orders "has been noted by partners." Before 2024 concluded, Australia had already received 72 aircraft out of its commitment to 100. Norway, another key partner, had completed its order of 52 F-35s by April 2025. In contrast, the UK has received just 38 jets and has yet to establish a firm timetable for acquiring the remaining 90 aircraft needed to reach its publicly stated goal of 138. This slow progress risks creating a perception of an unreliable partner, potentially impacting future collaboration and industrial benefits.

A tale of two variants: The F-35A and B

Further complicating the fleet plan was a recent government decision to purchase 12 F-35A models. This is the conventional take-off and landing variant of the jet, as opposed to the F-35B short take-off and vertical landing (STOVL) version that currently equips the UK's force. The F-35B's STOVL capability is essential for operating from aircraft carriers but comes with performance trade-offs in range and payload compared to the F-35A. The decision to acquire the 'A' model is seen as a significant win for the RAF, which has long argued for a mixed fleet to optimise capabilities for both land-based and sea-based operations.

A tug-of-war between Navy and Air Force

The acquisition of the F-35A variant highlights a long-running debate within the MoD. It is understood that the RAF would have preferred a split buy from the beginning, dedicating the more specialised F-35B models exclusively to carrier operations with the Royal Navy. The current force is operated jointly by RAF and Royal Navy squadrons. Buying a dozen F-35A jets signals a potential shift in strategy, creating a more distinct land-based force. This move could lead to greater efficiency for air force operations but also raises questions about the total number of carrier-capable F-35B jets the UK will ultimately purchase, a crucial number for the future of its carrier strike groups.

The Ministry of Defence responds

In the face of the NAO’s critical assessment, a representative for the MoD has mounted a defence of its management of the F-35 programme. The spokesperson insisted that the project is operating within its allocated funding. They also highlighted the substantial economic advantages flowing from the UK's involvement, stating it has generated £22 billion in contracts for British companies and created many thousands of employment opportunities. The MoD also sought to provide reassurance on readiness, claiming that two complete squadrons of the F-35 jets would be prepared for service before this year concludes. The ministry’s response focuses on the jet's world-class capabilities and its positive industrial impact, while disputing the severity of the financial and operational problems.

Looking ahead: A path to capability?

A report from the National Audit Office serves as a critical warning. Gareth Davies, who leads the NAO, stated the MoD must now make clear decisions on how to determine its priorities for resource allocation to fully realize the advantages of the F-35. The path forward is fraught with challenges. The ministry must urgently address the personnel and spare parts crisis to improve aircraft availability. It needs to provide a clear and credibly costed plan for the full fleet, including the integration of vital weapon systems. The F-35 remains a supremely capable aircraft, but turning that potential into a reliable and lethal fighting force requires a renewed focus on logistics, funding, and strategy. The security of the nation depends on it.