What is the height of the 'X' markings on a permanently closed runway?

The height of the 'X' markings on a permanently closed runway is standardized at 60 feet tall from end to end. This height is designed to ensure that the markings are visible from a significant distance, providing a clear indication to pilots that the runway is not in use and is closed to air traffic. The visibility of these markings is critical for maintaining safety in the airspace and preventing accidental landings on closed runways. By setting the height at 60 feet, it ensures that they can be easily seen from various angles and altitudes, especially during approaches and departures.