Definition
A Runway Visual Range value of 700 feet, meaning the horizontal distance a pilot can expect to see down the runway from the approach end is 700 feet, as measured by transmissometer equipment near the runway and reported in the approach minimums for certain Category II and Category III ILS approaches.
Plain English
The pilot will be able to see about 700 feet of runway ahead once down low on the approach. That is the visibility number used to decide whether the approach can be flown and the landing made.
Context Anchor
Seen on instrument approach minimums and in ILS approach category descriptions, especially for very low-visibility operations.
Derivation
RVR stands for Runway Visual Range. 'Visual range' simply means how far you can see. The number is given in feet because that is how runway visibility is reported in the United States; many other countries use meters.
Why Pilots Care
Determines whether an approach may be continued to landing or must be missed when visibility drops below authorized limits.
Grounding Statement
Imagine sitting in the cockpit just above the runway and being able to see only about two football field lengths of pavement ahead before everything dissolves into fog.
Intuition Check
Do not read RVR 700 feet as normal weather visibility for the whole airport. It is a runway-specific measured value showing how far the runway environment can be seen.
Example Sentence 1
Tower reported RVR 700 feet for Runway 27L, which was right at our Category II minimum.
Example Sentence 2
With reported RVR 700 feet the crew elected to continue the approach rather than execute a missed approach.