What is the background color of Runway Distance Markers (RDM)?

Runway Distance Markers (RDM) are used to indicate the distance remaining on the runway for pilots. The standard background color for these markers is indeed yellow. This color is selected specifically to provide high visibility against the runway surface and to stand out prominently in various lighting conditions. Yellow is typically associated with caution and alertness, making it an effective choice for informing pilots about critical distance information as they approach the landing phase.

Other colors like green and white are used for different purposes in aviation signage and ground markings. For example, green may indicate safe areas or runways, while white is often used for other permanent markings. Red is commonly associated with stop or prohibited areas. Thus, yellow is the distinctive color that serves the specific function of runway distance markers, designed to catch the attention of pilots quickly and effectively.