Evaluation of visual augmentation methods for rotorcraft pilots in degraded visual environments

Visual augmentation methods using three-dimensional-conformal scenery content presented on a see-through head-mounted display have the potential to support the pilot in degraded visual environments. This work evaluates combined state-of-theart visualization concepts in low-altitude flight close to obstacles and with limited visual ranges between 100 and 800 m. Therefore, a pilot-in-the-loop simulation scenario with an obstacle course has been developed 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 at lower visibility the pilot's velocity and the height-above-ground adjustments significantly increased when obstacle information was displayed head-up, while workload was reduced compared to an unassisted flight. Moreover, the time to contact at the onset of the obstacle avoidance maneuver increased and the safety margin maintained a minimum of 5-6 s for completely unexpected events.