Method and system for providing an aircraft drift advisory

Abstract

A system and method for issuing an aircraft drift advisory. In one embodiment, the system includes a head or eye tracker to monitor the rotational position of the pilot's line of sight with respect to the aircraft axis. The pilot's line of sight is compared to the direction of the aircraft. If the absolute value of the difference is greater than or equal to a predetermined angle, corresponding to the foveal cone of vision, the incremental aircraft drift distance is computed and used to update the cumulative aircraft drift distance. The cumulative aircraft drift distance is compared to the predetermined advisory criterion, which may be a constant, a uniform function of altitude or a function of altitude that is tied to a digital terrain map. When the cumulative aircraft drift distance equals or exceeds the advisory criterion, the pilot is given a drift advisory that the aircraft has drifted so as to prompt the pilot to adjust his line of sight to the direction of the drift. If the cumulative drift distance is less than the advisory criterion, the drift distance calculation is updated. In alternative embodiments, the drift distance is directly measured, and the time during which the drift distance equals or exceeds a threshold drift distance is compared to a criterion time to determine whether to issue the advisory. The system is designed to prevent a hovering aircraft from slowly drifting into contact with objects because the pilot is unaware of the drift for any reason.