We report the results of a part-task simulation evaluating the separate and combined effects of an electronic moving map display and newly developed HUD symbology on ground taxi performance, under moderate- and low-visibility conditions. Twenty-four commercial airline pilots carried out a series of 28 gate-to-runway taxi trials at Chicago O'Hare. Half of the trials were conducted under moderate visibility (RVR 1400 ft), and half under low visibility (RVR 700 ft). In the baseline condition, where navigation support was limited to surface features and a Jeppesen paper map, navigation errors were committed on almost half of the trials. These errors were virtually abolished when the electronic moving map or the HUD symbology was available; in addition, compared to the baseline condition, both forms of navigation aid yielded an increase in forward taxi speed. The speed increase was greater for the HUD than the electronic moving map, and greater under low visibility than under moderate visibility. These results suggest that the combination of electronic moving map and HUD symbology has the potential to greatly increase the efficiency of ground taxi operations, particularly under low-visibility conditions.