Evaluation of Visual Augmentation Methods for Rotorcraft Pilots in Degraded Visual Environments

Visual augmentation methods using 3D-conformal scenery content presented at a see-through head-mounted display have the potential to support the pilot in degraded visual environments. This work evaluates combined state-of-the-art visualization concepts in low-level flight close to obstacles and with limited visual ranges between 100 m and 800 m. Therefore, a pilot-in-the-loop simulation scenario with an obstacle course has been developed, in order to determine the control strategy of the pilot in low visibility situations, both with and without advanced visual assistance. Sixteen pilots participated in this experiment. The results show that the velocity and the height-above-ground adjustments of the pilots increase significantly at lower visibility and with obstacle information presented head-up, while workload is reduced compared to the unassisted flight. Moreover, the time-to-contact at the distance where the pilots initiated the obstacle avoidance maneuver increases and the safety margin maintains a minimum of 5 to 6 seconds for completely unexpected events. The early detection of obstacles with the head-mounted display allows more time for pilots to decide how to avoid a collision and thus increases their perceived safety.