Aeronautical Terms beginning with V
V-Bars
The flight director displays on the attitude indicator that provide control guidance to the pilot.
V-G Diagram
A chart that relates velocity to load factor. It is valid only for a specific weight, configuration, and altitude and shows the maximum amount of positive or negative lift the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds.
V-Speeds
Designated speeds for a specific flight condition.
V-Tail
A design which utilizes two slanted tail surfaces to perform the same functions as the surfaces of a conventional elevator and rudder configuration. The fixed surfaces act as both horizontal and vertical stabilizers.
V1
The maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. Also the minimum speed in the takeoff, following a failure of the critical engine at Vef, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance.
V2
Takeoff Safety Speed.
Va
The design maneuvering speed. This is the “rough air” speed and the maximum speed for abrupt maneuvers. If during flight, rough air or severe turbulence is encountered, reduce the airspeed to maneuvering speed or less to minimize stress on the airplane structure. It is important to consider weight when referencing this speed. For example, VA may be 100 knots when an airplane is heavily loaded, but only 90 knots when the load is light.
Va
Design maneuvering speed.
Va
The design maneuvering speed. The maximum speed at which full, abrupt control movement can be used without overstressing the airframe.
Validity
The extent to which a test measures what it is supposed to measure.
Vapor lock
A problem that mostly affects gasoline-fuelled internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporise due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude.
Vapor pressure
In meteorology, the pressure of water vapor in the atmosphere. Vapor pressure is that part of the total atmospheric pressure due to water vapor and is independent of the other atmospheric gases or vapors.
Vapor trail
Same as condensation trail—a cloud-like streamer frequently observed to form behind aircraft flying in clear, cold, humid air.
VAPS
Visual Approaches. An approach conducted under Instrument Flight Rules that authorizes the pilot to proceed visually and clear of clouds to the airport. Usually this will be used in conjunction with Visual Separation. When using Visual Separation, 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. Visual Separation requires less spacing between aircraft than radar separation allowing more aircraft to land in a given period of time.
VAR
Volcanic Activity Reporting
Variation
Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
Variation
Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
VASI
Visual Approach Slope Indicator.
VASI
Visual Approach Slope Indicator
Vb
Design speed for maximum gust intensity.
Vc
Design cruising speed.
VCOA
Visual Climb Over Airport
VCOA
Visual Climb Over the Airport
Vd
Design diving speed.
VDA
Vertical Descent Angle
Vdf / Mdf
Demonstrated flight diving speed.
VDP
Visual Descent Point.
Vector
A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.
Vector
A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.
Vectoring
Navigational guidance by assigning headings.
Vectoring
Navigational guidance by assigning headings.
Veering
Shifting of the wind in a clockwise direction with respect to either space or time; opposite of backing. Commonly used by meteorologists to refer to an anticyclonic shift (clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere).
Vef
The speed at which the critical engine is assumed to fail during takeoff.
Vei
Instrument flight never exceed speed, utilized instead of Vne for compliance with maximum limit speed requirements for instrument flight
Velocity
The speed or rate of movement in a certain direction.
Velocity
The speed or rate of movement in a certain direction.
Venturi tube
A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.
Venturi tube
A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.
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.
Vertical Axis
An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.
Vertical axis
An imaginary line passing vertically through the center of gravity of an aircraft. The vertical axis is called the z-axis or the yaw axis.
Vertical Card Compass
A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.
Vertical card compass
A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.
Vertical Navigation (VNAV)
Traditionally, the only way to get glidepath information during an approach was to use a ground-based NAVAID, but modern area navigation systems allow flight crews to display an internally generated descent path that allows a constant rate descent to minimums during approaches that would otherwise include multiple level-offs.
Vertical Separation
Separation established by assignment of different altitudes or flight levels.
Vertical speed indicator (VSI)
A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.
Vertical speed indicator (VSI)
A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.
Vertical Stability
Stability about an aircraft’s vertical axis. Also called yawing or directional stability.
Vertical stability
Stability about an aircraft’s vertical axis. Also called yawing or directional stability.
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.
Vertical visibility
The distance one can see upward into a surface based obscuration; or the maximum height from which a pilot in flight can recognize the ground through a surface based obscuration.
Very High Frequency
The frequency band between 30 and 300 MHz. Portions of this band, 108 to 118 MHz, are used for certain NAVAIDs; 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 Low Frequency
The frequency band between 3 and 30 kHz.
Very-high frequency (VHF)
A band of radio frequencies falling between 30 and 300 MHz.
Very-high frequency (VHF)
A band of radio frequencies falling between 30 and 300 MHz.
Very-high frequency omnidirectional range (VOR)
Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.
Very-high frequency omnidirectional range (VOR).
Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.
Vestibule
The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.
Vf
Design flap speed.
Vfc / Mfc
Maximum Speed For Stability Characteristics.
Vfe
The maximum speed with the flaps extended. The upper limit of the white arc.
Vfo
The maximum speed that the flaps can be extended or retracted.
VFR
Visual Flight Rules.
VFR
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.
VFR Aircraft
An aircraft conducting flight in accordance with 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 14 CFR Part 91. Use of the term does not relieve controllers of their responsibility to separate aircraft in Class B and Class C airspace or TRSAs as required by FAAO JO 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 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/her own decision.
VFR over the top
A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
VFR over-the-top
A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
VFR terminal area chart
At a scale of 1:250,000, a chart that depicts Class B airspace, which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
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 responsibility to separate aircraft in Class B and Class C airspace or TRSAs as required by FAAO JO 7110.65.
Vfto
Final Takeoff Speed.
VGSI
Visual Glide Slope Indicator
VGSI
Visual Glide Slope Indicator
Vh
Maximum speed in level flight with maximum continuous power.
VHF
Very High Frequency
VHF
Very High Frequency.
VHF Omnidirectional Range/Tactical Air Navigation
VORTAC.
Victor airways
Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas. Visual approach slope indicator (VASI). A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glide slope will see red lights over white lights.
Victor airways
Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.
VIP
Video Integrator Processor
Virga
Water or ice particles falling from a cloud, usually in wisps or streaks, and evaporating before reaching the ground.
Virtual Reality (VR)
A form of computer-based technology that creates a sensory experience allowing a participant to believe and barely distinguish a virtual experience from a real one. VR uses graphics with animation systems, sounds, and images to reproduce electronic versions of real-life experience.
Visibility
The greatest distance one can see and identify prominent objects.
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.
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.
Visual Approach Slope Indicator (VASI)
The most common visual glidepath system in use. The VASI provides obstruction clearance within 10° of the extended runway centerline, and to 4 nautical miles (NM) from the runway threshold.
Visual approach slope indicator (VASI)
A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights.
Visual Climb Over Airport (VCOA)
A departure option for an IFR aircraft, operating in visual meteorological conditions equal to or greater than the specified visibility and ceiling, to visually conduct climbing turns over the airport to the published “climb-to” altitude from which to proceed with the instrument portion of the departure. VCOA procedures are developed to avoid obstacles greater than 3 statute miles from the departure end of the runway as an alternative to complying with climb gradients greater than 200 feet per nautical mile. These procedures are published in the `Take-Off Minimums and (Obstacle) Departure Procedures’ section of the Terminal Procedures Publications.
Visual descent point (VDP)
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 runway environment is clearly visible to the pilot.
Visual flight rules (VFR)
Flight rules adopted by the FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the pilot must have in order to operate according to these rules. When the weather conditions are such that the pilot can not operate according to VFR, he or she must use instrument flight rules (IFR).
Visual flight rules (VFR)
Flight rules adopted by the FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the pilot must have in order to operate according to these rules. When the weather conditions are such that the pilot can not operate according to VFR, he or she must use instrument flight rules (IFR).
Visual Holding
The holding of aircraft at selected, prominent geographical fixes which can be easily recognized from the air.
Visual meteorological conditions (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
Visual meteorological conditions (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
Visual range
Runway visual range. An instrumentally derived horizontal distance a pilot should see down the runway from the approach end; based on either the sighting of high intensity runway lights or on the visual contrast of other objects, whichever yields the greatest visual range.
Visual Segment
Published Instrument Approach Procedure Visual Segment.
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/her own separation by maneuvering his/her aircraft as necessary to avoid it. This may involve following another aircraft or keeping it in sight until it is no longer a factor.
Vle
Landing gear extended speed. The maximum speed at which an airplane can be safely flown with the landing gear extended.
Vle
Maximum landing gear extended speed.
VLF
Very Low Frequency
VLJ
Very Light Jet
Vlo
Landing gear operating speed. The maximum speed for extending or retracting the landing gear if using an airplane equipped with retractable landing gear.
Vlo
Maximum landing gear operating speed.
Vlof
Lift-off speed. The speed at which the aircraft departs the runway during takeoff.
Vlof
Lift-off speed.
Vmc
Minimum control airspeed. This is the minimum flight speed at which a twin-engine airplane can be satisfactorily controlled when an engine suddenly becomes inoperative and the remaining engine is at takeoff power.
VMC
Visual Meteorological Conditions.
Vmc
Minimum control speed with the critical engine inoperative.
VMC
Visual Meteorological Conditions
Vmd
Minimum drag speed.
Vmini
Instrument flight minimum speed, utilized in complying with minimum limit speed requirements for instrument flight
Vmo
Maximum operating speed expressed in knots.
Vmo/ Mmo
Maximum operating limit speed.
Vmu
Minimum unstick speed.
VNAV
Vertical Navigation
Vne
Never-exceed speed. Operating above this speed is prohibited since it may result in damage or structural failure. The red line on the airspeed indicator.
Vne
The never-exceed speed. Operating above this speed is prohibited since it may result in damage or structural failure. The red line on the airspeed indicator.
Vnei
Never Exceed Speed-IFR.
Vno
Maximum structural cruising speed. Do not exceed this speed except in smooth air. The upper limit of the green arc.
Vno
Maximum structural cruising speed.
VOL
Volume. Usually used to indicate that the volume of aircraft exceeds the airport´s capacity.
VOR
Very-high Frequency Omnidirectional range.
VOR
Very High Frequency Omni Directional Range. 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.
VOR test facility (VOT)
A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, while others are limited to ground use only.
VOR test facility (VOT)
A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, while others are limited to ground use only.
VORTAC
A facility consisting of two components, VOR and TACAN, which provides three individual services: VOR azimuth, TACAN azimuth, and TACAN distance (DME) at one site.
VORTAC
A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN distance measuring equipment (DME) at one site.
Vortex
In meteorology, any rotary flow in the atmosphere.
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.
Vorticity
Turning of the atmosphere. Vorticity may be imbedded in the total flow and not readily identified by a flow pattern. Types are: absolute, negative, positive, and relative vorticity.
VOT
VOR Test Facility
VOT
A ground facility which emits a test signal to check vor receiver accuracy. Some VOTs are available to the user while airborne, and others are limited to ground use only.
Vp
Minimum dynamic hydroplaning speed. The minimum speed required to start dynamic hydroplaning.
VPA
Vertical Path Angle
Vr
Rotation speed. The speed that the pilot begins rotating the aircraft prior to lift-off.
Vr
Rotation speed.
VR
VFR Military Training Route
Vref
Reference Landing Speed
Vref
Reference Landing Speed.
Vref
The reference landing approach speed, usually about 1.3 times Vso plus 50 percent of the wind gust speed in excess of the mean wind speed.
Vs
The stalling speed or the minimum steady flight speed at which the airplane is controllable.
Vs1
Stalling speed or the minimum steady flight speed obtained in a specified configuration. For most airplanes, this is the power-off stall speed at the maximum takeoff weight in the clean configuration (gear up, if retractable, and flaps up). The lower limit of the green arc.
Vs1
The Stalling Speed or The minimum steady flight speed obtained in a specific configuration.
Vs1
The stalling speed or the minimum steady flight speed obtained in a specified configuration. For most airplanes, this is the power-off stall speed at the maximum takeoff weight in the clean configuration (gear up, if retractable, and flaps up). The lower limit of the green arc.
VSBY
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.
VSI
Vertical Speed Indicator.
VSI
Vertical Speed Indicator.
Vso
Stalling speed or the minimum steady flight speed in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down). The lower limit of the white arc.
Vso
Stalling Speed or The minimum steady flight speed in the landing configuration
Vso
The Stalling Speed or The minimum steady flight speed in the landing configuration.
Vso
The stalling speed or the minimum steady flight speed in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down). The lower limit of the white arc.
Vsr
Reference Stall Speed.
Vsr0
Reference Stall Speed In The Landing Configuration.
Vsr1
Reference Stall Speed In A Specific Configuration.
Vsse
Safe, intentional one-engine inoperative speed. The minimum speed to intentionally render the critical engine inoperative.
Vsw
Speed at which onset of natural or artificial stall warning occurs.
VTF
Vector to Final
VTOL Aircraft
Vertical Takeoff And Landing Aircraft.
Vtoss
Takeoff Safety Speed For Category A Rotorcraft.
VV
Vertical Visibility
VVI
Vertical Velocity Indicator
Vx
Best angle-of-climb speed. The airspeed at which an airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.
Vx
Speed For Best Angle Of Climb.
Vx
Best angle-of-climb speed. The airspeed at which an airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.
Vxse
Best angle of climb speed with one engine inoperative. The airspeed at which an airplane gains the greatest amount of altitude in a given distance in a light, twin-engine airplane following an engine failure.
Vy
Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.
Vy
Speed For Best Rate Of Climb.
Vy
Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.
Vyi
Instrument climb speed, utilized instead of Vy for compliance with the climb requirements for instrument flight
Vyse
Best rate-of-climb speed with one engine inoperative. This airspeed provides the most altitude gain in a given period of time in a light, twin-engine airplane following an engine failure.
Vyse
Best rate-of-climb speed with one engine inoperative. This airspeed provides the most altitude gain in a given period of time in a light, twin-engine airplane following an engine failure.
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