VFR MILITARY TRAINING ROUTES (VR)- Routes used by the Department of Defense and associated Reserve and Air Guard units for the purpose of conducting low-altitude navigation and tactical training under VFR below 10,000 feet MSL at airspeeds in excess of 250 knots IAS. 

VFR NOT RECOMMENDED- 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. To be given when the current and/or forecast weather conditions are at or below VFR minimums. It does not abrogate the pilot's authority to make his/her own decision. 

VFR-ON-TOP-  ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude (as specified in 14 CFR and as restricted by ATC). A pilot receiving this authorization must comply with the VFR visibility, distance from cloud criteria, and the minimum IFR altitudes specified in 14 CFR Part 91. The use of this term does not relieve controllers of their responsibil- ity to separate aircraft in Class B and Class C airspace or TRSAs as required by FAA Order JO 7110.65. 

VFR TERMINAL AREA CHARTS- (See AERONAUTICAL CHART.) 

VFR WAYPOINT- (See WAYPOINT.) 

VHF- (See VERY HIGH FREQUENCY.) 

VHF OMNIDIRECTIONAL RANGE/TACTICAL AIR NAVIGATION- (See VORTAC.) 

VIDEO MAP- An electronically displayed map on the radar display that may depict data such as airports, heliports, runway centerline extensions, hospital emergency landing areas, NAVAIDs and fixes, reporting points, airway/route centerlines, bound- aries, handoff points, special use tracks, obstructions, prominent geographic features, map alignment indicators, range accuracy marks, and/or minimum vectoring altitudes. 

VISIBILITY- 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. 

(Refer to 14 CFR Part 91.) (Refer to AIM.) 

a. Flight Visibility- The average forward horizon- tal 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. 

b. Ground Visibility- Prevailing horizontal visi- bility near the earth's surface as reported by the United States National Weather Service or an accredited observer. 

c. Prevailing Visibility- The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous. 

d. Runway Visual Range (RVR)- An instrumen- tally derived value, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end. 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. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway. RVR is horizontal visual range, not slant visual range. It is based on the measurement of a transmissometer made near the touchdown point of the instrument runway and is reported in hundreds of feet. RVR, where available, is used in lieu of prevailing visibility in determining minimums for a particular runway. 

1. Touchdown RVR- The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone. 

2. Mid-RVR- The RVR readout values obtained from RVR equipment located midfield of the runway. 

3. Rollout RVR- The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway. 

(See ICAO term FLIGHT VISIBILITY.) (See ICAO term GROUND VISIBILITY.) (See ICAO term RUNWAY VISUAL RANGE.) (See ICAO term VISIBILITY.) 

VISIBILITY [ICAO]- 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. 

