VASI -- VTOL AIRCRAFT
VASI-
(See VISUAL APPROACH SLOPE INDICATOR.)
VDF-
(See DIRECTION FINDER.)
VDP-
(See VISUAL DESCENT POINT.)
VECTOR- A heading issued to an aircraft to provide
navigational guidance by radar.
(See ICAO term RADAR VECTORING.)
VERIFY- Request confirmation of information; e.g.,
"verify assigned altitude."
VERIFY SPECIFIC DIRECTION OF TAKEOFF (OR TURNS
AFTER TAKEOFF)- Used by ATC to ascertain an aircraft's
direction of takeoff and/or direction of turn
after takeoff. It is normally used for IFR departures
from an airport not having a control tower. When
direct communication with the pilot is not possible,
the request and information may be relayed through
an FSS, dispatcher, or by other means.
(See IFR TAKEOFF MINIMUMS AND DEPARTURE PROCEDURES.)
VERTEX- The last fix adapted on the arrival speed
segments. Normally, it will be the outer marker
of the runway in use. However, it may be the actual
threshold or other suitable common point on the
approach path for the particular runway configuration.
VERTEX TIME OF ARRIVAL- A calculated time of aircraft
arrival over the adapted vertex for the runway
configuration in use. The time is calculated via
the optimum flight path using adapted speed segments.
VERTICAL SEPARATION- Separation established by
assignment of different altitudes or flight levels.
(See SEPARATION.)
(See ICAO term VERTICAL SEPARATION.)
VERTICAL SEPARATION [ICAO]- Separation between
aircraft expressed in units of vertical distance.
VERTICAL TAKEOFF AND LANDING AIRCRAFT- Aircraft
capable of vertical climbs and/or descents and
of using very short runways or small areas for
takeoff and landings. These aircraft include,
but are not limited to, helicopters.
(See SHORT TAKEOFF AND LANDING AIRCRAFT.)
VERY HIGH FREQUENCY- The frequency band between
30 and 300 MHz. Portions of this band, 108 to
118 MHz, are used for certain NAVAID's; 118 to
136 MHz are used for civil air/ground voice communications.
Other frequencies in this band are used for purposes
not related to air traffic control.
VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION-
(See VOR.)
VERY LOW FREQUENCY- The frequency band between
3 and 30 kHz.
VFR-
(See VISUAL FLIGHT RULES.)
VFR AIRCRAFT- An aircraft conducting flight in
accordance with visual flight rules.
(See VISUAL FLIGHT RULES.)
VFR CONDITIONS- Weather conditions equal to or
better than the minimum for flight under visual
flight rules. The term may be used as an ATC clearance/instruction
only when:
a. An IFR aircraft requests a climb/descent
in VFR conditions.
b. The clearance will result in noise abatement
benefits where part of the IFR departure route
does not conform to an FAA approved noise abatement
route or altitude.
c. A pilot has requested a practice instrument
approach and is not on an IFR flight plan.
Note: All pilots receiving this authorization
must comply with the VFR visibility and distance
from cloud criteria in FAR Part 91. Use of the
term does not relieve controllers of their responsibility
to separate aircraft in Class B and Class C
airspace or TRSA's as required by FAA Order
7110.65. When used as an ATC clearance/instruction,
the term may be abbreviated "VFR;"
e.g., "MAINTAIN VFR," "CLIMB/DESCEND
VFR," etc.
VFR FLIGHT-
(See VFR AIRCRAFT.)
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
own decision.
VFR-ON-TOP- ATC authorization for an IFR aircraft
to operate in VFR conditions at any appropriate
VFR altitude (as specified in FAR 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 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 FAA Order 7110.65.
VFR TERMINAL AREA CHARTS-
(See AERONAUTICAL CHART.)
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, NAVAID's and
fixes, reporting points, airway/route centerlines,
boundaries, handoff points, special use tracks,
obstructions, prominent geographic features, map
alignment indicators, range accuracy marks, 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 FAR Part 91.)
(See AIM.)
a. Flight Visibility- 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.
b. Ground Visibility- Prevailing horizontal visibility
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 transmissometer.
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 instrumentally
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.
3. Rollout RVR- The RVR readout values obtained
from RVR equipment located nearest the rollout
end of the runway.
(See ICAO term VISIBILITY.)
(See ICAO term FLIGHT VISIBILITY.)
(See ICAO term GROUND VISIBILITY.)
(See ICAO term RUNWAY VISUAL RANGE.)
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.
a. Flight Visibility-The visibility forward
from the cockpit of an aircraft in flight.
b. Ground Visibility-The visibility at an aerodrome
as reported by an accredited observer.
c. Runway Visual Range [RVR]-The range over
which the pilot of an aircraft on the centerline
of a runway can see the runway surface markings
or the lights delineating the runway or identifying
its centerline.
VISUAL APPROACH- An approach conducted on an instrument
flight rules (IFR) flight plan which authorizes
the pilot to proceed visually and clear of clouds
to the airport. The pilot must, at all times,
have either the airport or the preceding aircraft
in sight. This approach must be authorized and
under the control of the appropriate air traffic
control facility. Reported weather at the airport
must be ceiling at or above 1,000 feet and visibility
of 3 miles or greater.
(See ICAO term VISUAL APPROACH.)
VISUAL APPROACH [ICAO]- An approach by an IFR
flight when either part or all of an instrument
approach procedure is not completed and the approach
is executed in visual reference to terrain.
VISUAL APPROACH SLOPE INDICATOR-
(See AIRPORT LIGHTING.)
VISUAL DESCENT POINT- A defined point on the final
approach course of a nonprecision straight-in
approach procedure from which normal descent from
the MDA to the runway touchdown point may be commenced,
provided the approach threshold of that runway,
or approach lights, or other markings identifiable
with the approach end of that runway are clearly
visible to the pilot.
VISUAL FLIGHT RULES- Rules that govern the procedures
for conducting flight under visual conditions.
The term "VFR" is also used in the United
States to indicate weather conditions that are
equal to or greater than minimum VFR requirements.
In addition, it is used by pilots and controllers
to indicate type of flight plan.
(See INSTRUMENT FLIGHT RULES.)
(See INSTRUMENT METEOROLOGICAL CONDITIONS.)
(See VISUAL METEOROLOGICAL CONDITIONS.)
(Refer to FAR Part 91.)
(Refer to AIM.)
VISUAL HOLDING- The holding of aircraft at selected,
prominent geographical fixes which can be easily
recognized from the air.
(See HOLDING FIX.)
VISUAL METEOROLOGICAL CONDITIONS- Meteorological
conditions expressed in terms of visibility, distance
from cloud, and ceiling equal to or better than
specified minima.
(See INSTRUMENT FLIGHT RULES.)
(See INSTRUMENT METEOROLOGICAL CONDITIONS.)
(See VISUAL FLIGHT RULES.)
VISUAL SEPARATION- A means employed by ATC to
separate aircraft in terminal areas and en route
airspace in the NAS. There are two ways to effect
this separation:
a. The tower controller sees the aircraft involved
and issues instructions, as necessary, to ensure
that the aircraft avoid each other.
b. A pilot sees the other aircraft involved
and upon instructions from the controller provides
his own separation by maneuvering his aircraft
as necessary to avoid it. This may involve following
another aircraft or keeping it in sight until
it is no longer a factor.
(See and Avoid.)
(Refer to FAR Part 91.)
VLF-
(See VERY LOW FREQUENCY.)
VMC-
(See VISUAL METEOROLOGICAL CONDITIONS.)
VOICE SWITCHING AND CONTROL SYSTEM- The VSCS is
a computer controlled switching system that provides
air traffic controllers with all voice circuits
(air to ground and ground to ground) necessary
for air traffic control.
(See VOICE SWITCHING AND CONTROL SYSTEM.)
(Refer to AIM.)
VOR- A ground-based electronic navigation aid
transmitting very high frequency navigation signals,
360 degrees in azimuth, oriented from magnetic
north. Used as the basis for navigation in the
National Airspace System. The VOR periodically
identifies itself by Morse Code and may have an
additional voice identification feature. Voice
features may be used by ATC or FSS for transmitting
instructions/information to pilots.
(See NAVIGATIONAL AID.)
(Refer to AIM.)
VORTAC- A navigation aid providing VOR azimuth,
TACAN azimuth, and TACAN distance measuring equipment
(DME) at one site.
(See DISTANCE MEASURING EQUIPMENT.)
(See NAVIGATIONAL AID.)
(See TACAN.)
(See VOR.)
(Refer to AIM.)
VORTICES- Circular patterns of air created by
the movement of an airfoil through the air when
generating lift. As an airfoil moves through the
atmosphere in sustained flight, an area of area
of low pressure is created above it. The air flowing
from the high pressure area to the low pressure
area around and about the tips of the airfoil
tends to roll up into two rapidly rotating vortices,
cylindrical in shape. These vortices are the most
predominant parts of aircraft wake turbulence
and their rotational force is dependent upon the
wing loading, gross weight, and speed of the generating
aircraft. The vortices from medium to heavy aircraft
can be of extremely high velocity and hazardous
to smaller aircraft.
(See AIRCRAFT CLASSES.)
(See WAKE TURBULENCE.)
(Refer to AIM.)
VOR TEST SIGNAL-
(See VOT.)
VOT- A ground facility which emits a test signal
to check VOR receiver accuracy. Some VOT's are
available to the user while airborne, and others
are limited to ground use only.
(Refer to FAR Part 91.)
(See AIM.)
(See AIRPORT/FACILITY DIRECTORY.)
VR-
(See VFR MILITARY TRAINING ROUTES.)
VSCS-
(See VOICE SWITCHING AND CONTROL SYSTEM.)
VTA-
(See VERTEX TIME OF ARRIVAL.)
VTOL AIRCRAFT-
(See VERTICAL TAKEOFF AND LANDING AIRCRAFT.)
|