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  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.  3.  Rollout RVR- The RVR readout values  obtained from RVR equipment located nearest the  rollout end of the 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.  (See ICAO term FLIGHT VISIBILITY.)  (See ICAO term GROUND VISIBILITY.)  (See ICAO term RUNWAY VISUAL RANGE.)  (See ICAO term VISIBILITY.)  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.  c.  Prevailing Visibility- The greatest horizontal  visibility equaled or exceeded throughout at least half  the horizon circle which need not necessarily be  continuous.  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.  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.  night. Visibility is reported as statute miles, hundreds  of feet or meters.  (Refer to 14 CFR Part 91.)  (Refer to AIM.)  8/15/19 1/30/20  Pilot/Controller Glossary Pilot/Controller Glossary  PCG V-2 