Controlled-flight-into-terrain is a major contributor to aircraft accidents and one of its causes is spatial disorientation (SD). Pilots need to be trained to recognize potentially hazardous SD maneuvers, avoid these maneuvers, and override misperceived orientations. This paper demonstrates that this can only be done effectively once SD can be quantified.Critical flight maneuvers are evaluated quantitatively to illustrate the extent to which each produces spatial disorientation and potential accidents. It is shown that SD is a serious hazard to commercial and general aviation, not just to military aircraft.SD-related aircraft accidents can be prevented. To accomplish this goal, several avenues of approach are presented.