The average monthly flight hours of the UK’s F-35B Lightning II fifth-generation stealth fighter fleet peaked in the 2021-22 financial year, before falling away in 2022-2023, likely linked to the Carrier Strike Group 2021 (CSG21) deployment.

According to information released by the UK Ministry of Defence, detailing average monthly flying hours for the F-35B and P-8 Poseidon maritime patrol aircraft fleets, the figure peaked at 210 hours per month in FY2021-22, before dropping to 180 in FY2022-23. The two preceding years had seen 140 flight hours per month on average for the UK’s F-35B fleet in FY2020-21 and 160 hours for FY2019-2020.

The CSG 2021 deployment ran from May to December in 2021 and saw the embarkation of a flight of eight F-35B fighters from the Royal Air Force’s (RAF) 617 Squadron, augmented by 10 aircraft from the US Marine Corps, which operates the same B variant as the RAF and Royal Navy.

During the deployment, while operating in the Mediterranean Sea on the return leg to the UK, one UK F-35B crashed during take-off, sparking a rush to recover the downed aircraft from the seabed. The UK subsequently added another F-35B to its order with US prime Lockheed Martin.

Average monthly flight hours

The UK is contractually committed to the acquisition of 48 F-35Bs, with deliveries concluding by 2025, a significant reduction from the 138 aircraft espoused at the outset of the UK’s participation in the US-led multinational programme.

It is thought possible that the UK’s existing order of 48, once completed, could be increased to around 74 further down the production run, particularly as newer iterations, such as the Block IV upgrade package, are introduced.

A total of seven F-35Bs were expected to be delivered to the UK through 2023, with its current fleet standing at around 30 aircraft. Through 2022, six F-35Bs were delivered by Lockheed Martin. The first F-35B was delivered to a UK operational conversion unit based at Fort Worth, Texas, in 2012.

Charting the size of the UK F-35B fleet during the flight hour period, it can be extrapolated that the aircraft was worked particularly hard in FY2019-20 as a proportion of available airframes.

The UK air combat fleet is relatively new, with 31.8% of its military fixed-wing aircraft being under 10 years of age, according to figures from GlobalData, a sizeable portion of which will be the F-35B force.

The Poseidon P-8 MPAs are also new aircraft, having been procured to fill an airborne maritime patrol gap caused when the Nimrod MRA4s were axed in 2010. Deliveries of the first of nine P-8s to the UK began in 2019 and concluded in 2021.

Average monthly airframe hours for the UK P-8s reflected this increase in aircraft, rising from 30 hours in FY2019-20 to 190 in FY2022-23. The longer hours per airframe reflects the length of time the P-8s will spend on patrol, often lasting several hours.