A short discussion piece I wrote regarding spatial disorientation (SD) in unmanned aircraft operations. SD is complicated enough when you are in the seat! Conflicting or absent sensory inputs get even more complicated when the operator has a variety of experiences, locations, and displays.

The three types of Spatial Disorientation (SD) encountered by operators of aerial vehicles are recognized, unrecognized and incapacitating. Recognized SD occurs when there is a conflict between the aircraft position or motion and the operator’s sensory inputs which is noticed by the operator. Unrecognized SD is when the aircraft is in an unintended position or motion and the operator is unaware that a change has taken place.  Incapacitating SD is when the operator is unable to make control inputs to correct the situation, due to overwhelming conflicting sensory information.  While incapacitating can be catastrophic in manned aviation, it occurs rarely if ever in UAS operations (Cooke, 2006).  SD influence on mishaps is summarized nicely in the Cooke text:  “SD Mishaps occur when inaccurate operator perceptions result in inappropriate control inputs” (Cooke, 2006).

In manned aircraft, SD usually occurs from a mismatch between vestibular and proprioceptive cues, and visual cues that are received by the operator.  The visual system in the human accounts for a much larger ratio of sensory and cognitive processing so visual cues tend to dominate human perception of self motion in space, and operators can find it difficult or even impossible (in the case of incapacitating SD) to override visual sensations in order to right the aircraft.  In unmanned aircraft, vestibular cues and proprioceptive cues are not available so the operator relies on visual cues to judge vehicle motion and position.  This leaves the operator vulnerable to visual illusions and without the benefit of other modes of sensory input to tell him or her what the vehicle is doing.  UAS operators who work in a mobile ground control station such as a automobile, another aircraft or a ship would be subject to unrelated vestibular and proprioceptive cues which would exacerbate SD problems. Operators with manned aircraft flying experience could be more susceptible to SD due to the lack of vestibular and proprioceptive cues he or she is used to receiving to complement visual references.  Operators without manned aircraft experience may not understand how to compensate for visual illusions, such as the mishap cited by Cooke et al. (2006, p 139).

There are many variations in UAS configuration and operation that make UAS operators vulnerable to SD, including the type of display (egocentric, exocentric, orientation of cardinal direction) and type of control inputs (fully manual, full automatic or some combination of the two).  A common flight regime for SD is during night takeoffs and landings.  One idea to compensate for SD in this stage of flight would be to increase the salience (in size, location or color on the display) of instrument indications during night takeoffs and landings, as the lack of visual cues at night increase the number of ways in which an operator can misjudge vehicle position.   Another idea would be to increase automation when operating in night takeoffs and landings, again in order to compensate for the lack of visual cues and operator proneness to error. 

Spatial disorientation is a real concern in UAS operations, and reduction of the influence of SD in this growing industry promises to keep human factors experts employed for years to come.

Cooke, N. J., Pringle, H., & Pedersen, H. (Eds.). (2006). Human Factors of Remotely Operated Vehicles, Volume 7. Amsterdam, NLD: JAI Press. Retrieved from http://www.ebrary.com