You overdarkened the shot - easy to do :) - and there still isn't much background detail.
Clouds. Mountains. Buildings. Other planes. You know - details ;)
And try more dynamic angles. Use F1 view (free from Flight1 software) to help with this.
Try to sort out your problem with jaggies too. It really takes away from a shot.
Basic rule is that usually the original has to be good for the edit to look good. Look at other people's work. Copy it. That's how I learn.....and am still learning ::)

You're definitely improving though!!!