I like big height differences and that's why I made this map like it is now.
You don't see that kind of maps very often imo. (Maybe the airplane issue is just the reason?)
I have some pictures of the map, and of the problem too.
Here's the map. Its 16x16 in size. Maxheight=1100, minheight=0.

http://users.evtek.fi/~ilkkale/screen184.jpg
http://users.evtek.fi/~ilkkale/screen186.jpg
And here's a squadron of bombers bouncing off the wall :)

I set them to bomb the upper edge.
I've also found that lv1 gunships don't bounce off, they just fly through the terrain until they've reached their supposed normal altitude :/
It's a shame really, that the airplanes behave that way in such situations :/
I'm not sure if I should release this map as it is, with the airplane problems, or maybe do a drastically scaled downwards version (which would ruin all the fun of the high ground thing

What do you think?