Abstract: There is provided a method for displaying aircraft positions, which is capable of effectively avoiding the occurrence of near miss or collision. The method displays the terrain of an air space under air traffic control apparently in three dimensions on a display screen, displays aircraft marks at positions on the display screen so as to correspond to the three-dimensional positions of the respective aircraft, and displays a warning mark when a distance between two aircraft is shorter than a threshold value, wherein the warning mark comprises a triangle having three apexes, which comprise the aircraft marks, and a position that is apart from the aircraft mark of one of the aircraft along a vertical line extending perpendicular to the one aircraft toward a ground surface of the terrain by a distance corresponding to an altitude difference between both aircrafts on the display screen.