+1 upvoted for any improvement of the simulation of the inside of any vehicles. Unfortunately a Weak part in ArmA3.

+1
I want more simulation on vehicles.... When you play like me, as a crewman everytime, you want more simulations on them. For example, I would like to see more informations on the HUD of tanks/IFV, and having lot more possibility as the commander of it. In reality, the commander of the Leopard 2A4 for example can force align the gunner view with his view, in order to destroy targets more efficiently.

With regards to the simulation of the inside of the aircraft:
Ofcourse advanced flight model of planes, as we see in the control of helicopters.
Expected effects of congestion in moments of difficult maneuvers(dark or blured vision of player)
Sound effects of pressure (the heart beat, any noise), loss of hearing, ringing in the ears at enemy missile-hit in the player air vehicle.
Sound Effects hit projectiles, when the player is view from the first person.
More detailed damage model. For example right/left engine, right/left wing, fuel bak, hull integrity