SPATIAL DISORIENTATION IN US ARMY ROTARY-WING OPERATIONS

This paper describes two surveys concerning spatial disorientation (SD ) in U.S. Army rotary-wing operations that sought to assess the hazard and to identify recommendations to control it. One survey was of acci dent records, and the other was of aircrew experiences. Both surveys h ighlighted the magnitude of the problem. The accident survey showed th at 30% of class A to C accidents involved SD as a significant factor, while the aircrew survey showed that 78% of aircrews have been disorie nted (8% to the extent that flight safety was threatened). Both survey s showed a significant increase in SD associated with combat operation s. Several differences between the two surveys were noted: 90% of the reviewed accidents were thought to involve type I (unrecognized) SD co mpared with only 43% of the reported incidents; both pilots in a parti cular aircraft were considered to have been disoriented in at least 59 % of accidents compared with 23% of incidents; sudden loss of visual c ues (''brownout,'' ''whiteout,'' or inadvertent entry to instrument me teorological conditions) accounted for 25% of SD accidents compared wi th 13% of incidents; and 62% of the accidents occurred at night compar ed with only 36% of incidents. Neither survey showed any association b etween SD and fatigue or other human factors. The results of both surv eys suggested that crew coordination, alerting devices (e.g., audio wa rnings on the radar altimeter), flight information displays, and autop ilot functions would be good targets for improvement.