What does Runway Visible Range (RVR) measure?

Runway Visible Range (RVR) specifically measures the horizontal distance that a pilot can see when looking down the runway from its approach end. It is an important metric used in aviation to assess runway visibility conditions, particularly during landing and takeoff, when visibility can be compromised by weather conditions such as fog, rain, or snow. RVR is usually reported in meters or feet and provides essential information for determining whether the conditions meet the required visibility thresholds for safe operations.

While other options may pertain to visibility or weather, they do not accurately define the specific measurement that RVR represents. For example, cloud height above the runway is related to vertical visibility but does not reflect the horizontal measurement that RVR focuses on. Understanding RVR and its implications helps pilots make informed decisions regarding safe flight operations in varying weather conditions.