Obstacle-Avoidance displays for helicopter operations: Spatial versus guidance symbologies

One of the main hazards to helicopter low-level flight is obstacles on the flight route. It is essential that those obstacles be displayed to the pilots in a way that enables them to fly as safely as possible. Two different symbology concepts were suggested for display of obstacles: spatial and guidance displays. The spatial symbology shows the pilot where the obstacles are, whereas the guidance symbology recommends the preferable route and flight altitude. A personal-computer-based simulation study was conducted to compare four helmet-mounted display symbologies of obstacles. Three of the symbologies tested were of the spatial concept (one plan view and two conformal forward views), and the fourth was of the guidance concept. Twenty-one pilots completed a simulated task, similar to a searchand- rescue mission, under a degraded visibility environment condition while maintaining the exposure time as short as possible within two experiments. The results show better objective performance (shorter exposure time to threats, more targets detected, shorter reaction time to targets, and shorter reaction time to unexpected events) when using the conformal forward-view displays. This symbology was also subjectively preferred by the participants.