The National Research Council's (NRC) Cockpit Technologies Program flight tested a stereoscopic 3D display format to determine the feasibility of using pictorial and stereoscopic cues during helicopter instrument approach procedures (IAP). Three qualified test pilots flew a series of approach procedures using a modified conventional electronic flight instrumentation format, a pictorial display formate, and a pictorial stereoscopic display format. The preliminary evaluation focused on the effect of display format on pilot performance during the approach task, from an approach intercept to the decision height. Performance criteria such as aircraft speed error, localizer error, and glide slope error were measured. Additionally, pilots answered a questionnaire on each display format, and rated the workload required to fly the approaches using the Cooper-Harper scale. Pilots were able to complete approaches to safe landings using any of the display formats. Pilots reported that the pictorial format improved their situation awareness during the approach. Pilots also reported that the stereo cues incorporated in the display design did not significantly enhance their ability to perform IAP. The pictorial display contained several strong monocular depth cues such as occlusion, linear perspective, and motion flow; therefore the stereo cues were of limited value. Pilots most preferred the conventional display, which provided the most accurate tracking capabilities and lowest workload. Pilots encountered a few acceptance problems with the stereo display, most notably, losing the stereo effect when viewing the prototype stereo display off the central viewing axis.