That is a great shot! I really like that green gloomy feel. I'd give it a sturdy 8!

What could be better? I'd fly a little lower and bring the angle on the plane down.
This way you should get a better profile on the plane and the clouds.
This would also result in a little more blue sky which gives a little more 'breathing room' in the shot.

If you like, take a look at my Fedex Panda series and I think you'll get my point.