Here are my the 2 latest additions to my library:
They are both incredible volumes. I purchased "The Sky Their Battlefield" direct from the author, who very kindly signed it for me with a personalized message. It was a true labour of love, including the update to the original work that the image shows. It provides, day-by-day, all the casualties for the Allied (British Commonwealth, French and US) air forces, with brief details of where, when and how they were brought down (including accidents that resulted in deaths). It's a mighty tome but it was worth every penny.
"Black September 1918" is in a similar vein but focuses solely on the month in question which was the worst for Allied air casualties during the entire First World War (yes, worse than the Fokker Scourge of 1915 or "Bloody April" in 1917). Again, the authors have gone into meticulous detail to try and determine what happened.
Both volumes are reasonably well illustrated with high-quality photographs. I found both volumes to be incredibly useful in my family history research, providing much-needed context to the rather bland entries in a relative's logbook.