Which is more controlling during flight operations: RVR or visibility in statute miles?

RVR, or runway visual range, is more controlling during flight operations because it provides a precise measurement of how far a pilot can see down the runway, specifically at the approach and landing phase. This measurement is crucial during low visibility conditions, such as fog or heavy rain, where traditional visibility in statute miles may not accurately reflect the conditions a pilot will face on the runway.

RVR readings are derived from specific devices that measure visibility in terms of the distance along the runway that a pilot can see and is tailored to the operational needs of runway approaches. This means that RVR is particularly significant for determining whether a landing can be safely conducted, as it reflects the actual visual conditions faced by the pilot in critical phases of flight. For instance, if the RVR is below a certain threshold, it may be impossible for a pilot to land safely, regardless of the overall visibility in statute miles.

On the other hand, visibility in statute miles can be less reliable, especially in approach scenarios, because it is a broader measure of atmospheric conditions rather than specific runway visual conditions. Therefore, during flight operations, especially when assessing approaches and landings, RVR serves as a more controllable and actionable parameter, making it the primary measurement used by pilots and air