The Sky Their Battlefield Trevor Henshaw
This is an excellent book that lists all the Allied Casualties from Enemy Action in the First World War. In this book I found three occassions when my Grandfather was shot down.
Over The Front
This is a quarterly journal issued by the League of WW1 Aero Historians. In Volume 4, Number 2 (Summer 1989) There was an article on 48 Squadron by Frank W. Bailey and Paul Chamberlain. The article detailed the history of the Squadron and the incidents covered in the Squadron's Combat Reports. At the end of the article is a very useful list of all the personnel known to have served with 48 Squadron and a Combat Log of all the casualties suffered by the Squadron and enemy aircraft casualties inflicted by the Squadron.
Flight Magazine
Years and years worth of Flight magazine have been uploading onto the internet. Interesting articles I found were:
Unit History (3rd December 1936)Ancestry.co.uk
Bristol Fighter (7th November 1952)
There is a wide range of family history documents available on this site but of particular interest are:
Royal Aero Club Aviators’ Certificates
Medal Index Cards
The National Archives
From this website you can download:
RAF Officers Service RecordsCommonwealth War Graves Commission
Medal Index Cards
Air Combat Reports can be found using the search options
If your man was unfortunate to be killed during the War then you'll find him here.
The Great War Forum
The Aerodrome Forum
This two forums are great, and the combined knowledge is unmatched.