In the past, some helicopter pilots and even governing agencies have dismissed simulators as not realistic enough to provide effective training. Sitting in a fixed-base simulator, some pilots experience vertigo from the disconnect between what their eyes are seeing and what their ears and butts are experiencing. But the newest wave of helicopter-specific flight simulators use a combination of multi-axis motion actuators, high-definition graphics, and advanced computer programming to achieve realistic and effective training for helicopter pilots and crews. Some companies are even incorporating virtual reality (VR) and night-vision-goggle (NVG) simulators into their training curriculum.