Civilian contractors have always been employed on certain aspects of the repair and upgrade of RAF aircraft. Since 2004, the depth maintenance of Fast Jets has increasingly been performed by joint RAF/civilian teams. Contracts for aircraft maintenance are output-based and the number of civilian personnel required to achieve the output is decided by the contractor rather than the Ministry of Defence.
Information on the relative numbers of RAF and civilian personnel engaged in Fast Jet upgrade and repair in each of the last 10 years is not centrally held and could be provided only at disproportionate cost.