Gaydos SJ, Harrigan MJ, Bushby AJR. Ten years of spatial disorientation in U.S. Army rotary-wing operations. Aviat Space Environ Med 2012; 83:739–45.Introduction: Spatial disorientation (SD) has plagued aviation since its inception, contributing to numerous lost lives, destroyed or damaged aircraft, and a reduction in operational mission effectiveness. Military rotary-wing (RW) operations are not immune. The U.S. Army has retired many “legacy aircraft” represented in older studies, developed new training regimens for aircrew, continued to expand its night vision capabilities, and has prosecuted combat operations for some 10 yr utilizing new tactics, techniques, and procedures. For these reasons, it is important and relevant to re-engage the subject of SD among accidents within the Army’s RW community. Methods: The U.S. Army’s Combat Readiness/Safety Center database at Fort Rucker, AL, was queried for the previous 10 yr RW mishaps from fiscal year (FY) 2002 through FY 2011 (FY11 current through 01 July). Accidents identified as having SD as a contributing factor were selected. Results: From FY 2002 to FY 2011, there were 100 Class A through C rotary-wing flight mishaps involving SD. This represents 11% of all Class A through C rotary-wing flight accidents for this period. Of the 100 SD-related accidents, 22% involved fatalities, and 39% involved fatalities and/or injuries. The total number of RW SD-related accidents with fatalities represents 31% of the total helicopter accidents with fatalities for the 10-yr period. Discussion: This review of accident data confirms that SD remains a substantial issue for the Army aviation community and reinforces the importance and relevance of SD awareness, research, education, and training in RW operations.