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.)