Spatial Disorientation

Spatial disorientation is the inability to correctly interpret aircraft attitude, altitude or airspeed, in relation to the Earth or point of reference. Spatial disorientation is a condition in which an aircraft pilot's perception of direction does not agree with reality. While it can be brought on by disturbances or disease within the vestibular system, it is more typically a temporary condition resulting from flight into poor weather conditions with low or no visibility. Under these conditions the pilot may be deprived of an external visual horizon, which is critical to maintaining a correct sense of up and down while flying.

A pilot who enters such conditions will quickly lose spatial orientation if there has been no training in flying with reference to instruments. Approximately 80% of the private pilots in the United States do not have an instrument rating, and therefore are prohibited from flying in conditions where instrument skills are required. Not all pilots abide by this rule, and approximately 40% of the NTSB fatal general aviation accident reports list continuation of flight into conditions for which the pilot was not qualified as a cause.