(a)
TOUCHDOWN RVR - The RVR visibility readout values obtained from RVR equipment serving the runway Touchdown Zone.
(b)
MID RVR - The RVR readout values obtained from RVR equipment located mid-field of the runway.
(c)
ROLLOUT RVR - The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway.
VISIBILITY (ICAO) -
(1)
FLIGHT VISIBILITY - The visibility forward from the cockpit of an aircraft in flight.
(2)
GROUND VISIBILITY - The visibility at an aerodrome, as reported by an accredited observer.
(3)
RUNWAY VISUAL RANGE/RVR - The maximum distance in the direction of take-off or landing at which the runway or the specified lights or markers delineating it can be seen from a position above a specified point on its centering at a height corresponding to the average eye-level of pilots at touchdown.
VISUAL APPROACH (P/CG) - 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 (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/VDP - A defined point on the final approach course of a non-precision straight-in approach procedure from which normal descent from the Minimum Descent Altitude 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/VFR - 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, Instrument Meteorological Condition)
VISUAL HOLDING - The holding of aircraft at selected, prominent, geographical fixes which can be easily recognized from the air. (See Hold, Holding Fixes)
VISUAL METEOROLOGICAL CONDITIONS/VMC - Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling equal to or better than specified minima. (See Instrument Meteorological Conditions, Visual Flight Rules, Instrument Flight Rules)
VISUAL SEPARATION - A means employed by Air Traffic Control to separate aircraft in terminal areas. There are two ways to effect this separation:
(1)
The tower controller sees the aircraft involved and issues instructions, as necessary, to ensure that the aircraft avoid each other.
(2)
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 See and Avoid) (Refer to Federal Air Regulations Part 91)
VORTAC/VHF OMNIDIRECTIONAL RANGE/TACTICAL AIR NAVIGATION - A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN distance measuring equipment (DME) at one site. (See VOR, Distance Measuring Equipment, TACAN, Navigational Aids)
VORTICES/WING TIP 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 high pressure is created beneath it and an 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 Wake Turbulence, Aircraft Classes)
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