An aviation navigational system and method for predicting glide range for an aircraft for specific airports and other potential emergency landing locations in proximity to the aircraft. Information is presented to the pilot by complementing a conventional moving map display with symbols centered on each landing location. GPS altitude, airport elevation, and the aircraft's glide ratio are factored into an equation to determine glide range for each airport within proximity to the aircraft. A circular symbol representing the glide range boundary is displayed around each airport. Each circular symbol represents a sectional view of an imaginary inverted cone, having the apex thereof centered on a given landing location. The size and shape of the cone is based on the gliding performance of the aircraft and the altitude differential between the aircraft and the target landing location. As the altitude differential increases the radius of the circle increases. Conversely as the altitude differential decreases, the radius of the circle decreases. As long as the aircraft is anywhere within any one of the three-dimensional inverted cones displayed, as represented by one or more circles on a two dimensional display, it can safely glide to the landing location. This display concept is selectively referred to herein as "cones of safety."