Not bad, not bad at all! Although is it not 10 o'clock traffic? 

This is much better than your other attempts, one thing though, i agree the planes are a little fuzzy or blur, try to make them stand and and become clear and crisp, so it looks more like a photo

Good to see you are trying different methods though

The TCAS must be going crazy.

I noticed you blurred the edges of the plane again.  It may seem tempting, but you really shouldn't.  If you're having a problem with jagged edges, try using the line/curve tool.  select the same color of the section of the plane you're outlining (that shade of orange in this case) and make a thin curved line along the edge (only the section of the edge that is still the same shade of orange).  Gimp will automatically anti-alias the line which should cover up the pre-existing jagged edge.  If done carefully, the jaggies will be gone and the edit won't be noticed at all.  That's what i do often, though other's may tell you it's a bad idea.