The composition of an RFC squadron varied depending on its designated role, although the commanding officer was usually a major (in a largely non-operational role), with the squadron 'flights' (annotated A, B, C etc.) the basic tactical and operational unit, each commanded by a captain. A 'recording officer' (of captain/lieutenant rank) would act as intelligence officer and adjutant, commanding two or three NCOs and ten other ranks in the administration section of the squadron. Each flight contained on average between six and ten pilots (and a corresponding number of observers, if applicable) with a senior sergeant and thirty-six other ranks (as fitters, riggers, metalsmiths, armourers, etc.). The average squadron also had on complement an equipment officer, armaments officer (each with five other ranks) and a transport officer, in charge of twenty-two other ranks.