Terrain and obstacle avoidance displays for low-level helicopter operations in Degraded Visual Environments

Hazards to helicopter low level flight include terrain as well as obstacles such as antennas and electric wires on the flight route. New passive warning systems and active obstacle detection sensors can provide avoidance information and warning of potential collision. However new methods must be developed and tested for how this information is presented to the pilot during flight. The aim of the study is to develop and test obstacle display concepts that help the pilot to maintain low level flight and while avoiding obstacles. It compares two different Helmet Mounted Display (HMD) symbology concepts: The spatial display that shows flight obstacles on a spatial presentation of the environment, and the 3D guidance symbology that indicate to the pilot the flight direction and altitude to avoid obstacles. Four HMD displays were compared representing the two concepts in a PC-based simulated tactic flight task. Twenty one pilots completed a low level flight task using both display types (in two experiments). Task performance was measured for the primary task (maintaining low level flight), and secondary task (detection and classification of targets during flight). Results show better task performance when using the Blinking Scene Linked (BSL) obstacle display, which was the type of display that presented spatial information.