A method in an aircraft for identifying valid runway intersections for takeoff is provided. The method comprises: estimating a runway length required for takeoff based on aircraft parameters; estimating, at each of a plurality of runway intersections, a corrected runway length at the runway intersection by applying an elevation correction, a temperature correction, and a gradient correction; determining, based on the estimated runway length required for takeoff and the corrected runway length at each of the plurality of runway intersections, each valid runway intersection from the plurality of runway intersections whose corrected runway length is long enough for use by the aircraft for takeoff and each invalid runway intersection from the plurality of runway intersections whose corrected runway length is not long enough for use by the aircraft for takeoff; and signaling an aircraft display device to display on a map depicting the takeoff runway each invalid runway intersection.