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 th~ee 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.