I suspect that what we have here is yet another case of everyone speaking English without realizing that they are speaking different languages. The FARs and EU-OPS appear to take a very different approach to this. This is a bit long-winded, but the more I dug around, the more I realized that the authorities are very hard to pin down on this point. Some background first:
The explanation given in paragraph 4-213 of FAA Order 8900.10, Flight Standards Information Management System, is as follows:
RVR measurements are taken by a system of calibrated transmissometers and account for the effects of ambient background light and the runway light intensity. Transmissometer systems are strategically located to provide RVR measurement associated with one or more of the three basic portions of a runway: the touchdown zone (TDZ) portion, the mid runway (MID) portion, and the rollout (Rollout) portion.
RVR is an instrumentally derived value that reflects an artificially created seeing condition on or near the portion of the runway associated with the RVR report. This artificially created seeing condition is achieved by using high intensity runway edge, touchdown zone, and centerline lights. These lights increase the conspicuousness of the landing surface and “reach out” to the pilot thereby creating a seeing condition which is significantly better than the reported ground visibility or tower visibility. For any particular fog density, RVR will be significantly greater than reported visibility because RVR is based on the use of high intensity lights. Since RVR is based on high intensity lights, an RVR report only has meaning when associated with the seeing-conditions on or near the portion of the runway where the report was obtained (TDZ, MID, or Rollout). An RVR report has no meaning unless a pilot is also seeing the high intensity lights on which the report is based.
There are, in fact, two types of RVR systems in use in the States. The older one, known as a Tasker 500, uses a projected light beam as defined in FAA Order 6560.10B, Runway Visual Range:
In the United States, runway visual range is a value determined by instruments located alongside and about 14 feet higher than the centerline of the runway, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end; it is based on the sightings of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway.
The transmissometer projector and receiver are each mounted atop 14 foot towers either 250 or 500 feet apart. These towers are located at least 400 feet from the runway centerline on a line divergent with the runway centerline not to exceed 14.5˚ with the projector light beam directed angularly away from the runway. When an RVR system is installed between parallel runways and serves both runways the baseline of the transmissometer will be parallel to the runway.
Note that directionality is very much a factor here, in terms of beam direction and beam axis alignment with the specified runway.
The second system, known as the New Generation RVR, uses forward scatter meter technology. This relies on a single visibility sensor for each RVR location that measures the extinction coefficient. However, FAA Order 6560.23, New Generation RVR Program Management Plan, continues to state that RVR “represents the horizontal distance the pilot can see down the runway”.
This definition persists into the most recent FAA document, FAA-E-2772B, Performance Specification – PC Based Runway Visual Range System. This also focuses on the NGRVR using the forward scatter meter, and offers this product definition:
Product Definition: The RVR product is a calculated estimate of how far down a runway a pilot is expected to see. It is calculated using standardized equations from measurements of three parameters: extinction coefficient, ambient light level and the intensity of the runway lights. The RVR distance values shall be reported in feet.
Now, with respect to the operating rules...
FAR 121.655: Applicability of reported weather minimums.
In conducting operations under §§ 121.649 through 121.653, the ceiling and visibility values in the main body of the latest weather report control for VFR and IFR takeoffs and landings and for instrument approach procedures on all runways of an airport. However, if the latest weather report, including an oral report from the control tower, contains a visibility value specified as runway visibility or runway visual range for a particular runway of an airport, that specified value controls for VFR and IFR landings and takeoffs and straight-in instrument approaches for that runway.
Kent Jackson's explanation from his 2004 summary of Part 121 rules and Chief Counsel opinions says:
RVR or RVV controls only the particular runway for which it is installed. One cannot take off or land on a particular runway using the reported visibility for another runway. (example: You need ¼ mile visibility for takeoff on runway 24. Reported visibility 1/8 mile in fog. RVR for runway 13 is reported as 1600RVR (which corresponds to ¼ mile visibility). You cannot takeoff from runway 24 based upon the visibility for runway 13.
From what I can see of JAR-OPS 1.430, the approach taken is entirely different. Paragraph H of Appendix 1 to 1.430 lays out the use of a conversion of meteorological visibility to RVR for CAT I operations. There is no such animal in US rules; in fact, they go a long way out of their way to emphasize that RVR is not related to meteorological visibility. This may explain the divergence of opinion among colleagues on different sides of the Atlantic.
At the end of the day, however, the Federal Meteorological Handbook says that:
RVR shall be coded in the format, RDRDR/ VRVRVRVRFT, where R indicates that the runway number follows, DRDR is the runway number (an additional DR may be used for runway approach directions, such as R for right, L for left, and C for center), VRVR VRVR is the constant reportable value, and FT indicates that units of measurement are feet. For example, an RVR value for runway 01L of 800 feet would be coded:
R01L/0800FT.
So as I stated in an earlier post, I believe that RVR will always be reported with a runway number preceding it. That is the runway it is valid for.