Most helicopters are flown using visual reference to the ground. Whiteout is a dangerous, often self induced, phenomenon where rotor downwash stirs up fresh snow, creating a blinding, featureless white environment. It causes pilots to lose all sense of altitude, horizon, and depth perception, often leading to spatial disorientation and accidents during landing or takeoff in snowy conditions. There are techniques to help reduce the risk, such as hovering high enough to blow loose snow clear, or c