During World War I the British air services (Royal Flying Corps, Royal Naval Air Service, and after 1 April 1918, the Royal Air Force) awarded a variety of victory credits for aerial combat. Because of the rare nature of air-to-air fighting in 1914-15, any successful encounter with an enemy machine was cause for notoriety. Similarly, owing to the haphazard types of weapons carried in early aircraft, a "hard kill" resulting in destruction of a hostile airplane was even rarer. Therefore, what today would be regarded as "mission kills" were considered comparable to planes destroyed or captured. Credits were given for enemy aircraft (EA) "driven down" to a lower altitude or "forced to land" behind their own lines, presumably ending their usefulness for that sortie. Later, e/a driven down and considered "out of control" (OOC) were also credited to a pilot or gunner's score.
The "forced to land" (FTL) and "driven down" (DD) credits largely disappeared in the first half of 1916, but OOCs increased. By war's end, fully 40% of all British aerial victories fell into that nebulous category.
Unlike the Germans, whose rigid rule was "one kill, one pilot," the British also allowed full credit for a shared victory -- in at least one case, nine RAF pilots received individual recognition for an OOC. Therefore, the commonly accepted tallies that have been published since 1918 provide a skewed perception of RFC/RNAS/RAF aces' scores in relation not only to other World War I air forces, but World War II as well.
The data in Table I was compiled from Above the Trenches, a Grub Street volume published in 1990. The authors are noted aero historians C.F. Shores, Norman Franks, and Russell Guest.
Twelve other British Empire fighter pilots (Table II) achieved World War II equivalent scores of 20 or more:
According to Over the Front by Norman Franks and Frank Bailey (Grub Street, 1992) the French Air Service produced 187 aces--pilots and gunners each credited with five or more aerial victories. Of these, 159 were exclusively fighter pilots.
Like the German air service, throughout most of WWI the French credited only enemy aircraft assessed as destroyed in aerial combat or captured as a result thereof. During the early phase of the war, some nonlethal "kills" were credited, and early stars such as Roland Garros and Adolphe Pègoud received credit for both "hard" and "soft" kills. However, by early 1916 the criteria had solidified. Unlike the Germans, the Service Aeronautique granted full credit for shared victories, so it was possible for a pilot or gunner to be recognized as an ace without achieving a "solo" victory. In fact, eight French airmen did just that.
Despite the system of shared credits, the most successful French fighter pilots had few collaborative victories, and many escadrilles relied on their top scorer for the huge majority of the unit's success. In at least ten instances, the leading pilot achieved or participated in more than half the squadron victories, including Claude Haegelin who got 20 of SPA.100's 22 victories and Bernard Barny de Romanet with eight of SPA.167's ten. René Fonck was responsible for nearly two-thirds of SPA.103's tally, claiming 73 out of 111.
The following list (Table III) of the top 20 French aces shows official tallies as well as the decimal or fractional equivalent comparable to the US WWII standard.
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