Effects of Stereopsis, Collimation, and Head Tracking on Air Refueling Boom Operator Performance

This paper describes an evaluation of the effects of three practical display design variables on air refueling boom operator estimates of distance, ratings of image stability and ratings of visual comfort. Eight combinations of three design variables were tested. Two separate display systems, one collimated and the other direct view, were set up such that stereopsis and head tracking could be turned on or off. For each experimental condition, ten observers, of which eight were experienced boom operators, produced repeated estimates of distance between the boom nozzle and the receptacle on receiver aircraft positioned just seconds away from contact. The data collected revealed boom operator estimates of nozzle-to-receptacle distance were significantly more precise for the stereoscopic and collimated conditions with stereopsis having the largest effect. Ratings of visual comfort were higher for the collimated displays than for the direct view. Comfort ratings were higher when tracking was used with the stereoscopic displays but were decreased when tracking was used with the non-stereoscopic displays. The design implications of these and related results are discussed, and recommendations for the next-generation boom operator trainer are provided.