PCG VASI -- VTOL AIRCRAFT
VASI -- VTOL AIRCRAFT
VASI-
(See VISUAL APPROACH SLOPE INDICATOR.)
VDF-
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 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-
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-
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-
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.
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-
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.)
VISUAL HOLDING- The holding of aircraft at selected, prominent geographical
fixes which can be easily recognized from the air.
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.
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.)
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.
VORTAC- A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN
distance measuring equipment (DME) at one site.
(See DISTANCE MEASURING EQUIPMENT.)
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.
VOR TEST SIGNAL-
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.
(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.)