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Aeronautical Information Manual (AIM), page 720

Pilot/Controller Glossary 12/10/15

VFR MILITARY TRAINING ROUTES- 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 FAAO 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, minimum vector-
ing 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 Visibility Value (RVV)- The visibility
determined for a particular runway by a transmis-
someter. A meter provides a continuous indication of
the visibility (reported in miles or fractions of miles)
for the runway. RVV is used in lieu of prevailing
visibility in determining minimums for a particular
runway.

e. 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 is used in lieu of RVV and/or 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.

PCG V-2

Page 720 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   719 -- Page 720 -- 721