The most straight forward answer is "none". If you look towards the sky you will either see a dark or somewhat light dot in the sky, this will be a jet, most likely. Choppers are too slow to even benefit from camouflage, unless you are so skilled you can hoover-camp in a set area, something that is not wise to begin with.
The thing is that you will constantly be on the move, hence shifting background relatively often, any form of camouflage will then be obsolete. The only thing I can think of is flying at night, then a darker camouflage might be an idea.
If you are on a hardcore server with air, you are likely to find people spawning as engineers with AA loadout, so they can simply swipe across the sky and "see" you once you pass close enough.
For land vehicles, camouflage actually may matter. You can become harder to spot from air, and ground where you can blend in among snowy hills, green grass and tall trees. They need to look twice to notice you if you get a good enough spot.
So in short, when it comes for air vehicles, camouflage patterns are mostly for show, and serves little to no purpose beyond that.