Question to the Ministry of Defence:

To ask the Secretary of State for Defence, with reference to paragraph 11 of the Fifty-First Report of the Committee of Public Accounts, entitled The UK’s F-35 stealth fighter capability, HC 1232, for what reason the UK F-35 fleet achieved two-fifths of the level of availability of the global F-35B fleet between October 2024 and January 2025.

The Ministry of Defence (MOD) does not release availability data for operational security reasons; the National Audit Office (NAO) reporting of this metric was also appropriately redacted for this reason. The standard availability metric used by the NAO assumes that the assets are available 24/7; which skews the metric when calculating MOD capability usage, particularly Combat Air, as we do not keep the assets airborne 24/7.

There were a range of factors in the reported October 2024-January 2025 period including Force regeneration as part of standard Force Readiness cycles, and periods of planned personnel leave. This included a period when both Squadrons were deployed to a Carrier for an Exercise, routine post exercise regeneration with personnel leave and scheduled aircraft maintenance for many of the aircraft, and the Christmas and New Year leave period.