Thinking outside the box (maybe a little too far outside the box
) I'm wondering whether air flow in weather systems has a part to play. Traditionally we think that air flows horizontal to the surface and along the isobars with PGF and Coriolis playing their part. Is there a small vertical element? My books don't say so but............
I'm also thinking that you're operating below the level where geostrophic flow is true. In other words, with a tailwind you are actually flying towards an area of lower pressure. You may be at a constant pressure altitude but will be descending relative to the ground. Keep the same 'power' setting, add a bit of Isaac Newton and .....
PS. I've had a couple of drams so don't take this too seriously. Just some meanderings.