Why not control ground vehicles with the age-old, tried & tested, WASD and mouse combo.
W - accelerate forwards
S - decelerate/brake/reverse
A - turn left
D - turn right
Nice and simple.
And this would be a secondary system, but I believe using the mouse to aim the gun turrets (at least on tanks, I don't know about aircraft), would make more sense than the joystick - however that's debatable. It just seems to me that the current system is rather antiquated and unnecessarily complex. And whilst what we have does work, it should still be improved whenever possible.
Yossarian