The Sky Their Battlefield has all RFC/RNAS/RAF and (most?) US combat casualties. Airmen Died in the Great War (I think I have the title right) is all RFC/RNAS/RAF + USAS w/RAF deaths from all causes. The latter will not have WIA or POW; the former will not have deaths due to accident or illness. Check my reviews in the Book section elsewhere on this forum.
Another source for USA casualties is
Wings of Honor, also reviewed here.
French casualties, for the Western Front, can be found in Bailey & Cuny, French Air War Chronology, which again I believe is reviewed here.
Russian casualties will be in August Blume's forthcoming two volumes on the Eastern Front in WW1. I do not believe that Austro-Hungarian casualties have been catalogued. I think Serbian casualties have been catalogued, but in a book in Serbian. Greek, Rumanian, Belgian, if published, I have not seen.
Frank.