Aeronautical Terms beginning with V
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 Navigation Planning
Included within certain STARs is information provided to help you reduce the amount of low altitude flying time for high performance aircraft, like jets and turboprops. An expected altitude is given for a key fix along the route. By knowing an intermediate altitude in advance when flying a high performance aircraft, you can plan the power or thrust settings and aircraft configurations that result in the most efficient descent, in terms of time, fuel requirements, and engine wear.
Visual Approach
A visual approach is an ATC authorization for an aircraft on an IFR flight plan to proceed visually to the airport of intended landing; it is not an IAP. Also, there is no missed approach segment. When it is operationally beneficial, ATC may authorize pilots to conduct a visual approach to the airport in lieu of the published IAP. A visual approach can be initiated by a pilot or the controller.
Visual Climb Over the Airport (VCOA)
An option to allow an aircraft to climb over the airport with visual reference to obstacles to attain a suitable altitude from which to proceed with an IFR departure.
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.
Vapor Lock
A condition in which air enters the fuel system and it may be difficult, or impossible, to restart the engine. Vapor lock may occur as a result of running a fuel tank completely dry, allowing air to enter the fuel system. On fuel-injected engines, the fuel may become so hot it vaporizes in the fuel line, not allowing fuel to reach the cylinders.
Vector
A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.
Velocity
The speed or rate of movement in a certain direction.
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 Speed Indicator (VSI)
An instrument that uses static pressure to display a rate of climb or descent in feet per minute. The VSI can also sometimes be called a vertical velocity indicator (VVI).
Vertical Stability
Stability about an aircraft’s vertical axis. Also called yawing or directional stability.
VFR Terminal Area Charts (1:250,000)
Depict 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 which includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.
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 Flight Rules (VFR)
Code of Federal Regulations that govern the procedures for conducting flight under visual conditions.
Variation
Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
Vectoring
Navigational guidance by assigning headings.
Venturi tube
A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.
Vertical speed indicator (VSI)
A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.
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.
Vestibule
The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.
VFR-on-top
ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.
VFR over-the-top
A VFR operation in which an aircraft operates in VFR conditions on top of an undercast.
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.
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 meteorological conditions (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
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.
Validity
The extent to which a test measures what it is supposed to measure.
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.
VFR over-the-top
With respect to the operation of aircraft, the operation of an aircraft over-the-top under VFR when it is not being operated on an IFR flight plan.
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.
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).
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.
Virga
Water or ice particles falling from a cloud, usually in wisps or streaks, and evaporating before reaching the ground.
Visibility
The greatest distance one can see and identify prominent objects.
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.
Vortex
In meteorology, any rotary flow in the atmosphere.
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.
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.
Variation
Compass error caused by the difference in the physical locations of the magnetic north pole and the geographic north pole.
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.
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.
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 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.
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.
Vestibule
The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.
VFR on top
ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.
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.
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.
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 glideslope will see red lights over white lights.
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 meteorological conditions (VMC)
Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.
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.
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.
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.
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.
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.
Vy
Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.
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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