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                                               SILVER    SPRING, MARYLAND 20910   Letter    12-78

Date of Issue:     December 4, 1978                     Effective Date: December 1, 1978

In Reply Refer To: W521xl                                 File With: B-99

Subject:     NWS Participation in Runway Visual Range (RVR) Program

CANCELS: OML 21-76, dated December 1, 1976, same subject, filed with B-99

Purpose. This OML states NWS policy, responsibility, and areas of cooperation between the Federal Aviation Administration (FAA) and NWS in the RVR Program. FAA policy is given in FAA Order 6560.10, as amended.

  1. Program and Equipment Responsibilities. FAA is responsible for the RVR Program as well as ownership, maintenance, and supply support of transmissometers and all other RVR-related equipment.

  2. NWS Policy on Reporting RVR Data. NWS has no requirement for RVR data but agrees to report RVR according to the instructions in Federal Meteorological Handbook No. 1 (FMH-1) when FAA provides appropriate recorders in the NWS office.

  1. Ten-Minute RVR. NWS shall report 10-minute RVR v for the Designated RVR Runway or, as directed in FMH-1, for the Alternate (Secondary) RVR Runway. FAA shall specify the Designated and Alternate Runways, and once chosen, these runways are not subject to change because of current weather or current operations.

  2. Emergency RVR Reporting. When the digital readout in the Air Traffic Control facility is inoperative but a readout (digital, meter, or recorder) is available in the NWS office, NWS will provide a 1-minute RVR value at the time of notification and subsequent 1-minute values when the RVR is observed to change to equal, decrease below, or increase above 2,400 feet.

  3. Determining Acceptability of RVR Data. Although FAA is responsible for determining the status of the RVR system, NWS personnel will determine acceptability of RVR data according to the instructions in FMH-1 when local FAA facilities are closed.

  4. Retention of Transmissometer Recorder Charts. NWS shall retain completed charts from transmissometer recorders located in NWS offices for 30 days. Charts will be discarded after 30 days unless they cover an aircraft incident, in which case, it is the responsibility of FAA control tower or flight service personnel to obtain the charts from the NWS office.

  1. Policy on Cooperation with the FAA. NWS shall disseminate RVR data and, if NWS duties are not adversely affected, will cooperate with FAA in the following areas:

  1. Routine Performance Checks and Upkeep. NWS personnel may, if requested by FAA, help make performance checks, change charts, re-ink pens, and perform other nontechnical functions required for routine upkeep of FAA-owned RVR equipment in the NWS office. However, these duties, any follow-up action required, and the supplying of recorder charts, inks, and pens remain the responsibility of the FAA.

  2. Installing Recorders in NWS Offices. NWS will permit FAA to install, at most, two RVR recorders in each NWS office if installation is feasible considering space available and FAA requirements.

  3. Removing Recorders from NWS Offices. FAA may remove RVR equipment (including recorders) from NWS offices. However, without recorders in the NWS offices, RVR data will not be reported by the NWS.

George P. Cressman
Director, National Weather Service