| Abstract |
To investigate the breadth of visual illusions experienced by aviators flying with night vision devices (NVDs), an open-ended questionnaire was distributed to the military helicopter community in the fall of 1989. Of the 242 returned questionnaires, there were 221 night vision goggle (NVG) reports and 21 thermal imaging system (FLIR) reports. Most sensory events occurred at night, during low illumination, good weather, and over varied terrain. Contributing factors included inexperience, division of attention, and fatigue. Frequently reported illusions were misjudgements of drift, clearance, height above the terrain, and attitude. Also reported were illusions due to external lights, and distributed depth perception caused by differences in brightness between NVG tubes. Other respondents cited hardware problems and physiological effects. There were no obvious differences between the experiences of NVG users and FLIR users. Although incidence rates cannot be inferred from these data, the variety of expected aviator anecdotes in this report will be useful to all those concerned with human factors and safety of NVDs. |
