Here's a quick comparison highlighting some of the features for both bodies:
With the D5200 you get a newer sensor with a higher megapixel count and some other in camera editing (HDR)and video-related goodies but give up some semi-pro like features:
-fine tuning (nice to have when lenses are a little out of spec)
-Ability to focus and meter a wide range of lenses (e.g none AF
-I and AF
-S lenses can't be autofocused)
(not that big a deal but convenient)
to name a few..
I guess it will come down to where the emphasis is (e.g photo vs video) and how far you want to go with your hobby. The features listed above will be more valuable to a photo enthusiast than a casual user. You have evaluate your needs and decide which features are more important to you.
For me the D7000 is a no-brainer because of the AF
-fine tune and greater lens support capabilities. I also like the fact that it has dual dials and dedicated buttons for many functions. For you that may not matter though so take it as just an opinion.
Also, for aviation pics both cameras are more than adequate by a mile. Even my previous body, an entry-level D3100 did an excellent job (with a decent lens of course).
[Edited 2012-12-17 21:04:39]
Nikon D7000 / Nikkor 105mm AF f2.8 / Nikkor 35 f1.8G / Nikkor 50 f1.8D / Nikkor 85mm / Nikkor 300mm f4 AF