What symbol is used to mark closed runways and taxiways?

The symbol used to mark closed runways and taxiways is represented by a white or yellow "X." This distinctive marking serves as a critical visual cue for pilots, indicating that a particular runway or taxiway is not in service and should not be used for landing, takeoff, or taxiing. The use of contrasting colors—white or yellow—ensures high visibility against the surrounding runway and taxiway surfaces, even under various weather conditions or at a distance.

Understanding this marking is essential for maintaining safety and preventing accidents during ground operations, as it clearly communicates to pilots that the area is off-limits. This marking is regulated by aviation authorities to provide uniformity and clarity across airports, contributing to safer flight operations.