The data is derived from Squadron records in Ian Philpott's The Birth of the Royal Air Force. While the book does a good job of noting when certain aircraft were taken up by each of 274 squadrons and when they were retired, it doesn't say whether one example of a certain type of aircraft was added to the roster or ten of them, so I have assumed an even split between all of the types in use in any one month. I have removed from the charts any types used in England from squadrons bound for foreign service, but Home Defense squadrons aircraft are included for their full tenure. The charts do include aircraft used in lesser-known theaters like the Middle East. There is some RNAS data included from the period where they joined the RAF, but the data does not include seaplanes and flying boats. Numbers were sometimes adjusted up or down a percent to account for rounding errors. The types are sorted with each season from most-used to least-used planes.
- Most armed planes in 1914 and early 1915 had light or jury-rigged armaments. They were more Scout than Fighter.
- The Morane-Saulnier L was sometimes flown as a single-seat fighter and sometimes as a two-seat reconnaissance craft.
- In the latter half of its long career, the F.E.2b transitioned more to a night bomber, but it hard to determine the rate at which that occurred, so the tables here just show its raw use without regard to its role.
- Most Strutters we used in the reconnaissance and bombing roles rather than as a fighter, but it is impossible to determine which proportions were used for which role. So this data reflects their overall usage without regard to the role.
- The Bristol M.1C was never used on the Western Front.
- 1918 use of the Avro 504K was as a night fighter only.