Runway Visual Range (RVR) Procedures PDF

60 (d) use oil or soap water to clean the equipment. References 1. Procedures for IAF Met Service - IAP 3202 2. Technical Circular - Air HQ RUNWAY VISUAL RANGE (RVR...

60 (d) use oil or soap water to clean the equipment. References 1. Procedures for IAF Met Service - IAP 3202 2. Technical Circular - Air HQ RUNWAY VISUAL RANGE (RVR) 69. An automated system utilizes Transmissometer technology to assess. Three set of assemblies are installed near Touchdown zone, Midpoint and Stop End point of the runway and values are shown on various RVR displays (kept in offices) as well as RVR server. Wherever horizontal visibility is computed by serviceable instrumented RVR system, RVR display reading shall be made and reported in current weather reports, throughout the periods when either the manually reported horizontal visibility or the RVR for one or more runways available for landing is observed to be less than or equal to 2000m. Continued operation of the equipment during visibility in excess of 2000m is to be specified in local orders based on local conditions. Guidelines to be followed for reporting RVR by the stations equipped with RVR under the project "Modernization of Air Field Infrastructure (MAFI) are as follows: - (a) Displayed RVR value of Touch Down Zone (TDZ) of runway in use to be appended in METAR on Mausam Online in "Supplementary Info Column" whenever horizontal visibility is equal to or less than 2000m. (b) Runway Visual Range shall be reported in steps of 25m when the RVR is less than 400m; in steps of 50m when it is between 400m to 800m; and in steps of 100m when the runway visual range is more than 800m. (c) Averaging of RVR. The averaging period shall be one (01) minute for local routine, ADDITIONAL reports and ten (10) minutes for METAR and SPEC', except when the 10-minute period immediately preceding the observation includes a marked discontinuity in runway visual range values, only those values occurring after the discontinuity shall be used for obtaining mean values. (Note: A marked discontinuity occurs when there is an abrupt and sustained change in runway visual range, lasting at least 2 minutes, which reaches or passes through the values included in criteria for the issuance of SPECI reports). (d) Reporting Procedure. An observer should follow the following procedures while reporting RVR: - (i) RVR should be reported in the form "(Name of element) (Runway) (Runway section) (RVR Value)". If the RVR is observed from only one location along the Runway I.e. Touch Down Zone, it shall be included without any indication of location (For Example if RVR on Runway 24 is  61 1100 meters than it is to be reported in METAR/ SPECI as R24/1100 and in local routine and ADDITIONAL reports as RVR RWY 24 1 100M). (ii) When RVR is observed from more than one location along the Runway then: - (aa) The value representative of the Touch Down Zone (TDZ) shall only be reported in METAR/SPECI and no indication of location on the Runway shall be included (Example: - R35/0400). (ab) The local routine and SPECIAL observation shall have the value representative of all locations in a manner such that TDZ shall be reported first, followed by values representative of the MidPoint (MID) and End Point (END) and the locations for which these values are representative shall be indicated (Example: - RVR RWY 17 TDZ 600M MID 500M END 400M). (iii) When a station has more than one Runway available (parallel or cross), in that case, RVR of both the live Runway Ends are to be reported. For example, live runway 24 or 30 (cross-runway) will be reported as R24/0800 R30/1200 and live runway 28 or 29 (parallel runway) will be reported as R28/0700 R29/1200. (iv) In local routine, METAR and SPECI, the RVR shall be reported in steps of 25 m when the RVR is less than 400 m; in steps of 50m. when it is between 400 m to 800 m and in steps of 100 m and when it is more than 800 m. Any observed value, which does not fit the reporting scale in use, shall be rounded down to the nearest step in the scale. (v) The lower limit of RVR shall be considered as 50 m and the upper limit is 2000 m. Outside of these limits, local routine, METAR and SPECI shall merely indicate that RVR is less than 50 m or more than 2000 m. (vi) When the RVR is above the maximum value and horizontal visibility is less than 2000 m, it shall be reported using the abbreviation "ABV" in local routine/special and the abbreviation "P' in METAR and SPEC', followed by the maximum value that can be determined by the system. (Example: - METAR/SPECI R14/P2000; Local routine/special RVR RWY 14 ABV 2000M) (vii) When the RVR is below the minimum value, which can be determined by the system in use, it shall be reported using the term I'BLW" in local routine/special and the abbreviation "M" in METAR and SPECI, followed by the minimum value that can be determined by the system. (Example: - METAR/SPECI RIO/M0050; Local routine RVR RWY 10 BLW 50M) (vii) If the RVR values during the 10-minute period have shown a distinct tendency, such that the mean during the first 05 minutes varies  62 by 100 m or more from the mean during the second 05 minutes of the period, this shall be indicated. When the variation of the RVR values shows as upward or downward tendency this shall be indicated by abbreviation "U" or "D" respectively. In circumstances when actual fluctuations during the 10-minute period indicate no distinct tendency, this shall be reported using the abbreviation "N". When indications of tendency are not available, no abbreviations shall be included (For example RI 2/1 IOOU). UPPER AIR SOUNDING SYSTEM Introduction 70. Directorate of Met, Air HQ (VB) has procured and installed Qty 10 Upper Air Sounding Systems (UASS) at various operational IAF bases. UASS is utilised for observation of upper air meteorological parameters like temperature, humidity, pressure, wind direction and speed at a very fine resolution up to an altitude extending well beyond troposphere. These parameters provide immense inputs to the Met observers, forecasters and aviators. UASS has various IT and communication related components in it and hence needs to be operated and maintained professionally. Working Principle 71. powered telemetry (Greek words tele=remote, and metron = measure) instrument package carried into the atmosphere by a weather balloon of either natural rubber latex or a synthetic latex that measures various atmospheric parameters and transmits them by a radio to ground receiver, operating at HF signal 400-406 MHz. Wind profiles from radiosonde are derived from tracking the displacement of the balloon from launch site as function of time using Global Positioning System (GPS). An Overview & Components of UASS 72. Various components of Upper Air Sounding System are illustrated below: -