jack, for a first try, that's really good, well done!!!
i don't know how good your pc is, but you might want to turn up your texture size in AH, and also turn anti-aliasing on, if your PC is powerful enough. it will make the plane graphics much nicer.
as for your actual shot, one problem is that the background is very vivid. if you turned down the contrast and turned upa the brightness a bit, it may help the kates blend in a bit better.
my first pic was very sucky, and it didn't blend well either, you'll learn
it comes quickly. check out screenshotart.com, specifically the composites forum. they used to have great tutorials but they're down atm. they should be back up soon. take a lookaround that site, see if you can pick yp some hints
wtg, it's a great first try! also, next time, try to take your pics in the film viewer, it allows you to get nicer camera angles
press altR ingame instead of altS and it will record a film, then go to your aces high 2 folder, enter the films folder and watch the most recent one. open it up in fullscreen mode, get it to the angle you like, and press printscreen to transfer it into your image editor