I use the Rebel XS / 1000D, which is the previous generation of the T3
/ 1100D. It's a good little camera, though a bit light on some features that I now want.
However, in the last few months, I've upgraded my lens lineup to include the 17-40 F4L and the 70-200 F4L, and suddenly I'm much less intent on upgrading my camera.
I'm certainly not suggesting you go spend $1500 on lenses right away; I'm just saying that even the 1000D was/is adequate for what I currently use it for. I've had it for a little over 2 years, and I still don't think I've hit the ceiling with it yet.
As far as aviation photography goes, my main complaint is the sloooowwww frame rate. I shoot RAW, and 1.5 frames per second for up to 4 frames (3 frames in practice, I've found) is not optimum. But it just teaches you that you have to make your shots count, especially if you want to get different angles as an airplane flies by. Even if I had a camera with a true burst mode, I'm not sure I would make use of it; going through 10+ images per airplane is not appealing.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".