When is a runway classified as wet?

A runway is classified as wet when 25% or more of its surface exhibits a glossy, wet appearance. This classification is critical for pilots and air traffic control as it affects aircraft performance during takeoff and landing. Wet conditions can reduce friction between the aircraft's tires and the runway, increasing the risk of hydroplaning and affecting stopping distances.

The definition emphasizes the visual aspect of the runway. When 25% or more of the runway appears glossy, it indicates significant moisture that can influence operational safety. Different classifications of runway conditions exist to help pilots and crews assess the environmental factors that may impact their flight operations effectively. A runway classified as "fully dry" would indicate no moisture present and thus poses minimal risks. Similarly, while a runway with 10% or less standing water might not be classified as wet, it does not meet the threshold for a glossy appearance, which is what the correct answer outlines. Patches of snow would suggest different runway conditions and do not directly relate to the wet classification.