An advisory provided by a flight service station to a pilot during a preflight or inflight weather briefing that flight under visual flight rules is not recommended. It does not abrogate the pilot's authority to make his own decision. A pilot receiving this authorization must comply with the VFR visibility, distance from cloud criteria, and the minimum IFR altitudes specified in FAR Part 91. The use of this term does not relieve controllers of their responsibility to separate aircraft in Class B and Class C airspace or TRSA's as required by FAAO 7110.65. The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.
Visibility is reported as statute miles, hundreds of feet or meters.
The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. Prevailing horizontal visibility near the earth's surface as reported by the United States National Weather Service or an accredited observer. The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway. It is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range.