Comparing Pilots' Taxi Performance, Situation Awareness and Workload Using Command-guidance, Situation-guidance and Hybrid Head-up Display Symbologies

This study investigated pilots' taxi performance, situation awareness and workload while taxiing with three different head-up display (HUD) symbology formats: Command-guidance, Situationguidance and Hybrid. Command-guidance symbology provided the pilot with required control inputs to maintain centerline position; Situation-guidance symbology provided conformal, scenelinked navigation information; while the Hybrid symbology combined elements of both symbologies. Taxi performance was assessed with average taxi speed and root mean square error (RMSE) from the centerline. Situation awareness and workload were assessed using a 3Dimension SART and a 7-point scale, respectively. Taxi speeds were highest and RMSE from centerline lowest with Situation-guidance and Hybrid symbologies. Situation awareness was highest and workload lowest with Situation-guidance and Hybrid symbologies. These results are thought to be due to cognitive tunneling induced by the Command-guidance symbology. Situation-guidance (and Hybrid) HUD symbologies provided a common reference with the environment, which may have supported better distribution of attention.