Simulated Helo Ground Target Acquisition under Different Sun Angles and Ground Textures

Abstract

This study investigated the effect of sun angle and ground texture on tank target acquisition using a 1:1000 terrain table to simulate a pop-up maneuver. Using a three-by-two repeated measures design, three groups of ten subjects each were tested at one of three simulated sun angles (0, 90, and 180 degrees) and at two terrain textures (hilly and flat). Starting at a maximum simulated slant range of 8500 feet, slant range was reduced by 500 foot steps during successive 30-second trials until a correct target detection occurred. Although the main effects of sun angle and terrain texture on slant range and total search time were not significant, a highly reliable interaction between these variables was found. For the hilly portion of the terrain table, the 90-degree sun angle group had a significantly shorter slant range and required significantly more search time than the zero or 180-degree sun angle groups. This result is attributed to the interaction of large amounts and depths of shadows in hilly terrain and the difficulty of acquiring a tank target when its shadow is located at the side of the tank.