Survey of spatial disorientation in military pilots and navigators.

The direction of future spatial disorientation (SD) research and training is shaped primarily by the outcome of formal investigation of aircraft accidents and incidents. However, another source of vital information is aircrews' experience of SD that does not result in reported incidents.A short postal SD survey was distributed to 5 Naval Air Squadrons, 22 Joint Helicopter Command Units, and 7 Royal Air Force stations in the United Kingdom. There were 752 questionnaires, including responses from 562 pilots and 149 navigators, that were returned.Analysis was conducted primarily on the pilot data. The most frequently experienced SD episodes were "the leans" (by 92% of respondents), loss of horizon due to atmospheric conditions (82%), misleading altitude cues (79%), sloping horizon (75%), and SD arising from distraction (66%). In general, the frequency of SD episodes and ratings of severity of the worst ever SD episode were positively related to flying experience (p < 0.05). Overall, pilots who had received in-flight SD training reported more episodes of SD than those who had not participated in this training (p < 0.05). Differences in types of SD experienced were found between aircraft categories, e.g., more episodes of SD during night vision goggle use were reported by rotary-wing pilots compared with fast-jet aviators (p < 0.05).This preliminary survey has shown that SD is still a significant hazard of military flying. Overall, this study shows that the postal questionnaire is a useful tool for assessing how SD training and experience may benefit the recognition of situations that may cause SD. However, it is difficult to access those situations where aircrew were truly disorientated.