I would personally like it to be a base to prevent mine laying but that's totally fine anyways.
It would be interesting if that airfield was the only source of planes - which would mean a tighter control over it being necessary.
It was my original idea but I didn't liked the fact that only one team would have planes at a time. This is still a pretty important flag though, because you get more planes when you have it.
I also wanted "quite a lot" of planes in the sky so the start planes plus the airfield seems to be giving a good amount.