Definition
A Runway Visual Range value reported from a sensor located near the midpoint of the runway, indicating the horizontal distance a pilot can expect to see down the runway from that midfield position. It supplements the touchdown zone RVR and, where installed, the rollout RVR, and is a controlling value for certain low-visibility approach operations such as CAT II and CAT III approaches.
Plain English
It's a visibility measurement taken from a device sitting next to the middle of the runway, telling you how far you'd be able to see down the runway from that point.
Context Anchor
Seen in Category II and III instrument approach information, where visibility may be reported separately for the beginning, middle, and far end of the runway.
Derivation
Midfield simply means 'the middle part of the field,' where 'field' is an old aviation term for an airport or landing area. RVR stands for Runway Visual Range. Together it points to where the visibility reading is taken: not at the threshold, not at the far end, but in the middle of the runway.
Why Pilots Care
It helps pilots gauge whether visibility remains adequate for landing or if a missed approach is required.
Grounding Statement
Picture a foggy runway with a sensor near the halfway point measuring how far the runway lights can be seen from there.
Intuition Check
Midfield does not mean flying over the middle of the airport. Here it means the RVR reporting point near the middle of the runway.
Example Sentence 1
For this CAT II approach, the touchdown zone RVR was 1,800 feet and the midfield RVR was 1,600 feet, both above the required minimums.
Example Sentence 2
The crew noted improving midfield RVR before continuing the approach to minimums.