PROBLEM TO BE SOLVED: To solve a problem of poor visibility of a radar display screen in radar display technology for use in air traffic control, which occurs when the amount of information is huge and display of flight positions of aircraft overlaps with display of a system time, weather, runways, obstacles, flight plans and the like.SOLUTION: In a radar display device for use in air traffic control, a sub-window of flight altitudes is displayed based on information on flight positions of aircraft present in an operation area specified on a main window.
