时间：2011-04-18 00:52来源：蓝天飞行翻译 作者：航空 点击：次
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1. Touchdown RVR. The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone. PCG V.2 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 FLIGHT VISIBILITY.)(See ICAO term GROUND VISIBILITY.)(See ICAO term RUNWAY VISUAL RANGE.)(See ICAO term VISIBILITY.)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 aero-drome 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. (See AIRPORT LIGHTING.)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. (See AIM.)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.)(Refer to 14 CFR Part 91.)(Refer to AIM.)VISUAL HOLDING. The holding of aircraft at selected, prominent geographical fixes which can be easily recognized from the air. (See HOLDING FIX.)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 SEGMENT. (See PUBLISHED INSTRUMENT APPROACH PROCEDURE VISUAL SEGMENT.)PCG V.3 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. (See SEE AND AVOID.)(Refer to 14 CFR Part 91.)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.)(Refer to AIM.)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. (See NAVIGATIONAL AID.)(Refer to AIM.)VOR TEST SIGNAL. (See VOT.)VORTAC. A navigation aid providing VOR azimuth, TACAN azimuth, and TACAN distance measuring equipment (DME) at one site. (See DISTANCE MEASURING EQUIPMENT.)(See NAVIGATIONAL AID.)(See TACAN.)(See VOR.)(Refer to AIM.)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. |
