F-35 spares shortfall exposed as carrier surged to 24 jets

The Chair of the Public Accounts Committee has sharply criticised the Ministry of Defence over its management of F-35 spare parts, after the MoD’s Permanent Secretary wrote to the committee acknowledging that a carrier strike group deployment to the Middle East was conducted with insufficient spares to support the aircraft embarked, the UK Defence Journal understands.

The letter, dated 30 April 2026 and written by Permanent Secretary Jeremy Pocklington, was sent in response to the PAC’s October 2025 report on the UK’s F-35 stealth fighter capability. It reveals that during Operation HIGHMAST, the UK surged 24 F-35B aircraft onto a Queen Elizabeth-class carrier despite the Afloat Spares Pack being sized to support only 12 aircraft.

The shortfall was mitigated by drawing on the Deployable Spares Pack and taking additional spares from the RAF Marham Base Spares Pack, while maritime logistics challenges occasionally led to missed resupply opportunities during the deployment.

PAC Chair Sir Geoffrey Clifton-Brown did not hold back in his response. “At the heart of any military planning is sound logistics. The UK sent an aircraft carrier with 24 F-35 fighter jets on it to the Middle East — with not enough spare parts to support them. Twelve aircraft spare parts packs were sent to service twenty-four aircraft, and it is no surprise that as a result spares had to be shipped out from RAF Marham to make up the difference.”

“In an increasingly dangerous world, our military and the country need more than this half-baked approach from the MoD. Our brave fighting men and women, before being sent into potential harm’s way, must have absolute certainty that they are well-supported in their equipment, with clear and reliable supply lines. But this correspondence shows an entirely unacceptable incompetence that flies in the face of any kind of sensible planning from the Ministry of Defence,” he added.

The Permanent Secretary’s letter also addresses broader F-35 availability challenges. Pocklington states that while incremental improvements are expected through spares investment, workforce growth, and reprioritisation, sustained achievement of availability targets is unlikely under the current global sustainment model. Mission capable rates during Operation HIGHMAST were broadly comparable to the global F-35B average, though the letter notes that post-deployment recovery from the operational tempo and corrosion remediation activity has since reduced those rates.

Corrosion, worsened by maritime exposure, is identified as a growing concern across the programme. The MoD says it is working with UK and US industry partners on deeper inspections and recovery, enhanced preventative practices, and longer-term corrosion-resistant solutions within the broader F-35 programme, while acknowledging a short-term reduction in availability as maintenance activity intensifies to clear the backlog.

On workforce, the letter states that engineering posts for the Lightning Force have been increased to 168, split 58% RAF and 42% Royal Navy, but that current fill rates stand at approximately 75%. The RAF has plans to fill its remaining engineering posts by 2032, a timeline driven by the up to three years required to make engineers fully competent on the aircraft type. RAF Marham is also described as a less preferred posting location, with efforts underway to improve its attractiveness including career path development and infrastructure investment.

On the question of a standoff capability gap before SPEAR-3 is fully integrated, the letter confirms that approval has been given to procure the Small Diameter Bomb II through a Foreign Military Sales arrangement with the United States, providing an interim precision standoff option for the F-35 until SPEAR-3 enters service.

Regarding accommodation at RAF Marham, the letter confirms that four new single living accommodation blocks are under construction, with an overall completion date of May 2027. A third F-35 squadron is planned for 2033, with infrastructure readiness targeted for April 2032, though both timelines remain subject to the finalisation of the Defence Investment Plan.