this is a feature of aces high that occurs when you maneuver, your virtual boday is jostled about the cockpit a tiny bit thus reflecting the effects of such maneuvering.
I feel its realistic but it is my wish that we one day have a slider for belt tightness that operates by reducing head and body movement ie:"checking six" in exchange for reduced cockpit head jerks.
so if you are able to turn your body around to peer around the rear of the airplane you get the feeling of being thrown about the cockpit anytime you maneuver