Helicopter operations require a well-controlled and minimal lateral drift shortly before ground contact. Any lateral speed exceeding this small threshold can cause a dangerous momentum around the roll axis, which may cause a total roll-over of the helicopter. As long as pilots can observe visual cues from the ground, they are able to easily control the helicopter drift. However, when visibility is reduced or even obscured, e.g. due to night, fog, or dust, this controllability diminishes. Therefore helicopter operators could benefit from some type of "drift indication" that mitigates the influence of degraded visual environment.
With continuous technology advancement helmet-mounted displays (HMD) will soon become a spreading technology. At the present state HMDs are still expensive and are mostly reserved for military operations. The symbol sets fielded are designed for well trained staff and special missions. Investigating some of those symbol sets revealed that lateral drift indication doesn’t live for what it promises. With practice these symbol sets assist well during the approach but lack of proper cues once the helicopter hovers. Present developments also focus on three dimensional symbol sets that are conformal with the environment. All of them present a virtual landing pad. These types of see-through synthetic vision displays allow several new methods of information visualization.
Generally humans derive ego motion by the perceived environmental optical flow. To enhance this perception a pattern motion was implemented in a conformal HMD symbol set which amplifies the measured own ship movement. The paper presents results from an experimental study with 18 pilots from civil and military operators. In this study the forward landing zone border was replaced by an animated dashed line for indicating the amplified ego motion.