‘Disappointing return on £11bn investment’: Just 1/3rd of UK F-35 fighter jet fleet are fully mission capable
July 12, 2025
Only a third of the UK’s F-35s can perform all their intended missions, a new government report reveals.
The report from the National Audit office also found that only half are mission capable compared with the MoD target. Nevertheless, the report also notes the F-35s offer significantly increased capabilities to the UK.
Only one-third of UK’s F-35s fully mission-capable
The United Kingdom’s National Audit Office (NAO) has released a report detailing delays, infrastructure gaps, and personnel shortages in the UK’s F-35 Lightning II programme that are undercutting the fleet’s readiness.
NAO says there has been a “disappointing return” on the £11 billion the UK has so far spent on the jets. It adds that estimated plans to expand the fleet would cost more than three times what the British Ministry of Defence (MoD) had initially forecast.
Importantly, NAO claimed that the F-35’s fleet’s “full mission capable rate” was around a third of the MoD’s target.
“Full mission capable” means the aircraft can perform all of its seven core missions. “Mission capable” refers to readiness for at least one. Only half of the fleet was found to be mission capable at any one time.
For context, it is considered normal for a third of the fleet of almost any type of fighter jet to be down for maintenance at any one point.
Meanwhile, plans to equip Britain’s F-35s with weapons able to strike ground targets from a safe range while preserving the aircraft’s stealth profile have been pushed back to the early 2030s.
The NAO report was not all negative. It underscored the advanced capabilities of the 5th-gen F-35 stealth fighter and the increased capabilities it offers the UK.
The report also noted “…in recent years the MoD’s F-35 programme team has demonstrated effective day-to-day management, working collaboratively to deliver capability.”
UK’s significant participation in the F-35 programme
The United Kingdom is the only Tier One partner in the US-led F-35 programme. The UK’s leading defence contractor, BAE Systems, is one of the top three contractors in the programme, with the other two being Lockheed Martin and Northrop Grumman.
In all, the United Kingdom contributes around 15% to all F-35s built. All F-35s feature extensive BAE software code and other BAE components as well as Martin-Baker ejection seats. The F-35B STOVL variants also have the Rolls-Royce LiftSystem for taking off and landing vertically.
The F-35 project supports thousands of jobs in the United Kingdom, providing £22 billion worth of work for UK companies.
The UK F-35 fleet is growing
The report notes that of the 48 F-35B fighter jets currently on order, 38 have been delivered. One of these was lost as it tumbled into the sea in 2021 after taking off from the HMS Queen Elizabeth aircraft carrier.
Royal Navy F-35s were again in the news in June 2024 after a wayward F-35B had to make an emergency landing in India after it lost the carrier and was running low on fuel.
The UK has committed to purchasing a total of 138 F-35s, of which 12 will be F-35As and the remaining F-35Bs. The naval F-35Bs are jointly operated by the Royal Air Force and Royal Navy. The F-35As are to restore the RAF’s ability to deliver nuclear weapons from aircraft.
The UK’s policy is to be able to use the F-35 at a time or place of its choosing and be able to deploy an aircraft carrier strike group with up to 24 F-35Bs. These are to remain in service until 2069.
