Britain is failing to get the most out of its most advanced fighter jet amid availability issues largely as a result of shortages, a damning new report has warned. The National Audit Office (NAO) found in 2024, the UK F-35B fleet was only capable of performing all its required missions at a rate of approximately one-third the Ministry of Defence (MoD) target.
The UK’s independent public spending watchdog described the stealth aircraft’s availability as “poor” and “far below” the goals set by defence chiefs. It also warned the programme is suffering a number of delays and the whole-life cost of the project is more than three times that publicly forecast by the MoD. Head of the NAO, Gareth Davies, said: “The F-35 programme offers significantly improved capability and considerable economic benefits to the UK.
“But the capability benefits are not being fully realised due to delays, infrastructure gaps and personnel shortages.
“The MoD now needs to decide where to prioritise its resources to improve capability in a way that maximises the full benefits of the F-35 programme to the UK.”
Each F-35B costs around £88 million and they can operate from land and the Royal Navy’s aircraft carriers.
Thirty-eight F-35Bs have been delivered to the UK but only 37 are in service after one crashed into the sea as it took off from HMS Queen Elizabbeth in 2021.
The UK has committed to buying 138 aircraft and another 10 are on order, but there is no approved timetable for purchasing the rest, the NAO said.
The watchdog said it forecasts the whole-life programme for the F-35s to cost £71 billion – considerably more than the £18.76 billion the MoD has publicly reported.
It said availability issues were largely caused by engineer and spare parts shortages, while also noting “an emerging issue with higher corrosion than expected in maritime environments”.
It said the MoD has “previously underestimated” the number of engineers required but steps are being taken to reduce gaps.
The NAO also found the aircraft’s ability to perform at least one of its seven possible required missions was around half the MoD’s target.
The UK’s availability goals are lower than the global programme’s, the watchdog added.
Availability issues are also resulting in pilots having fewer flying hours than the MoD wants, despite reducing the requirement from 10 hours per month to 7.5 hours, the report found.
The NAO also raised concerns over delays.
Full Operating Capability is expected to be declared at the end of 2025 – two years later than planned – and with several gaps against its initial requirements.
It warned the MoD is “far behind” the planned delivery dates for integrating UK-developed Spear 3 and Meteor missiles onto the F-35, explaining they aren’t expected to be in full service until the 2030s with interim alternatives being pursued.
The report says the aircraft currently lacks a “standoff weapon to attack ground targets from a safe range, which will impact its effectiveness in contested environments”.
Full delivery of the first batch of 48 aircraft is also behind schedule due to a combination of financial pressure and problems with the global programme, according to the NAO.
An MoD spokesperson said: “The National Audit Office’s report rightly recognises the world-class capabilities of the F-35 fighter jet, as well as its significant economic benefits – including £22 billion of work for UK companies, creating thousands of jobs.
“The programme continues to operate within its approved budget and the UK will have two full squadrons of F-35 fighter jets ready for deployment by the end of this year.
“We also recently announced we will purchase 12 F-35As, supporting 20,000 jobs in the UK, and join NATO’s dual capable aircraft nuclear mission, as the government delivers greater security for working people through its Plan for Change.”
