Spatial Disorientation: A Survey of U.S. Army Rotary-Wing Aircrew.

A survey of 299 aircrew in current flying practice was performed at five U.S. Army airfields within CONUS. Respondents were asked a number of questions about their worst ever episode of spatial disorientation SD and their worst episode in the 4 months prior to the survey. They also were asked to classify episodes as minor, significant, or severe according to the threat to flight safety. Opinions also were sought on various aircraft types and flight conditions. In the final part of the questionnaire, they were asked about their experience of break-off and giant hand phenomena. Analysis of the data showed that 78 percent had suffered SD during their flying career 8 percent had suffered severely enough to put flight safety at risk. Twenty-two percent had suffered in the 4 months prior to completing the questionnaire 2 percent severely enough to put flight safety at risk. In 33 percent of worst ever episodes, the event had affected conduct of the mission while flying accuracy had been affected in 64 percent. The figures for the 4-month data were 35 percent and 68 percent. Brownout, whiteout, and inadvertent entry to instrument meteorological conditions IMC were the most easily identifiable source of severe episodes of SD, but they accounted for 13 percent of the worst ever episodes. The leans accounted for 44 percent of episodes. Few other episodes could be linked to well known problems. Aircrew were not initially aware of being disoriented in 43 percent of worst ever episodes 38 percent of episodes when they were looking out of the aircraft cockpit. Experience had no apparent protective effect against either the incidence or severity of episodes.