Spatial disorientation: more than just illusion.

Despite aggressive efforts in spatial disorientation (SD) research, hardware development, and training, the operational impact of SD in terms of crew and aircraft losses remains significant. Current training in spatial orientation is primarily composed of didactic lectures on the anatomy and physiology of the sensory systems. Significant efforts have been concentrated on reproducing various types of visual and vestibular "illusions" that pilots might encounter in flight, with limited and varying success. Unfortunately, the terms of "SD" and "illusion" have been used synonymously, leading to the general belief that if one were to be exposed to a specific type of illusion, one can prevent or avoid SD mishaps. Another setback is the inability of ground-based devices to reproduce the flight envelope. Often the demonstration of a specific illusion ends abruptly without further explanation or how these illusions can affect pilot performance. Demonstration of illusions seldom deals with the precipitating factors. We should provide pilots with skills to anticipate and assess the risk of SD during mission planning. Pilots should be sensitized to the physical and mental performance decrement during sensory conflicts and inadequacies. Recommendations should also be made on possible ways to recover from SD should they become disoriented. Special attention should be drawn to the properties of various flight displays that may contribute to SD. G tolerance and disorientation should be examined together in high performance aircraft as there is a close relationship between exposure to acceleration and maintaining orientation. The motto for counteracting SD is: anticipate, avoid, and counteract SD.