Abstract
The contribution of stereopsis to aviation has long been a topic of interest, but there is no consensus on its impact. This is in part due to the diversity of methodologies and tasks used, but also reflects the availability of monocular depth cues that can support altitude estimation. Here, we evaluated the contribution of monocular and binocular depth cues to altitude estimation in a simulated low hover task commonly performed by helicopter aircrew. Using a stereoscopic display, trained aircrew (n=31) estimated the altitude from a skid to the ground plane under stereoscopic and monocular viewing conditions. The ground plane was rendered with four textures at a range of altitudes. Altitude estimation was more accurate in stereoscopic than monocular conditions. Under monocular viewing, observers scaled their estimates with distance, but substantially underestimated the amount of depth. Comparison of these results with those obtained using naïve observers (Deas et al., in press) showed that the aircrew were more accurate in monocular test conditions than naïve observers, but the performance of both groups was significantly improved when stereoscopic depth information was available. This pattern of results suggests that while aircrew can learn to capitalize on monocular depth cues for specific in-flight tasks, stereopsis makes a substantial contribution to operational performance for rotary wing altitude estimation.