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runway visual range
- Definição1
- The maximum distance in the direction of takeoff or landing at which the runway, or specified lights or markers delineating it, can be seen from a position above a specified point on its centerline at a height corresponding to the average eye level of pilots at touch-down (ICAO). A height of approximately 16 ft (5 m) is regarded as corresponding to the average eye level of pilots at touchdown. In practice, the RVR cannot be measured directly from the position specified in the direction but is an assessment of what a pilot would see from that position. The system consists of a transmissometer projector along with related items, a transmissometer receiver (detector) and related items, a recorder, a signal data converter with its related items, and a remote digital or remote display programmer. The projector and the receiver are mounted on towers either 250 or 500 ft (75 or 150 m) apart. A known intensity of light is emitted from the projector and is measured by the receiver. Any obscuring matter such as rain, snow, dust, fog, haze, or smoke reduces the light intensity arriving at the receiver. The resultant intensity measurement is converted to an RVR value by the signal data converter. These values are displayed by readout equipment in the associated air traffic facility and updated approximately once every minute for controller issuance to the pilots. The signal data processor receives information from the transmissometer, and the sensing of day or night conditions. From these values, appropriate RVR values are computed. An RVR transmissometer established on a 250-ft (75 m) baseline provides digital readout to a minimum of 600 ft (200 m), whereas that with a 500-ft (150 m) baseline is restricted to a minimum value of 1000 ft (300 m). Various types of RVR are: (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.
- Fonte1
- KUMAR, Bharat (ed.). An illustrated dictionary of aviation. New York: McGraw-Hill, c2005. 752 p.
- Definição2
- The range over which the pilot of an aircraft in the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.
- Fonte2
- CRANE, Dale (ed.). Dictionary of aeronautical terms. 4th ed. Newcastle: ASA, 2006.
- Definição3
- An instrument derived horizontal distance a pilot should see down the runway from the approach end. RVR is based on either the sighting of high-intensity runway lights or on the visual contrast of other objects, whichever yields the greatest visual range.
- Fonte3
- AGÊNCIA NACIONAL DE AVIAÇÃO CIVIL. RBAC 01: regulamentos brasileiros de aviação civil. Definições, regras de redação e unidades de medida. [S.l.], 2008. (Regulamentos Brasileiros de Aviação Civil)
- Definição4
- An estimate of the maximum distance at which the runway, or the specified lights or markers delineating it, can be seen from a position above a specific point on the runway centerline.
- Fonte4
- FEDERAL AVIATION ADMINISTRATION. Instrument procedures handbook: FAA-H-8261-1A. 2nd ed. Newcastle: ASA, 2007.
- Nota adicional1
- Sigla em inglês: RVR.
- Contexto
- In local routine reports, local special reports, METAR and SPECI, the runway visual range shall be reported in steps of 25 m when the runway visual range is less than 400 m; in steps of 50 m when it is between 400 m and 800 m; and in steps of 100 m when the runway visual range is more than 800 m. Any observed value which does not fit the reporting scale in use shall be rounded down to the nearest lower step in the scale.
- When instrumented systems are used for the assessment of runway visual range, computations should be made separately for each available runway.
- Subárea1
- Aeronautical Meteorology
- Related Term
- runway visibility value
- Português
- alcance visual da pista
- Imagem
Transmissometer providing runway visual range information.
Fonte: http://en.wikipedia.org/wiki/File:Transmissometer.jpg
