A method, computer software product, and system to generate altitude callouts according to proximity to a runway at an airport or heliport includes determining whether the helicopter is flying in proximity to the runway and automatically selecting an altitude threshold increment set based upon the determination. The threshold increment set including a plurality of altitude threshold values. A calculated terrain clearance value is calculated for each of the plurality of altitude threshold values. A suitable warning is automatically generated according to the comparison. Selecting an altitude threshold increment set includes selecting one of the group consisting of first altitude threshold increment set including a plurality of higher altitude threshold values and a second altitude increment set including the plurality of higher altitude threshold values and further including a plurality of lower altitude threshold values.