Originally Posted by
MarkVI
For clarity: I've seen RVR reported for multiple runways (R18L/0500;R18R/0500), but how would I see dilineated positions?
Typically, the lower the vis, the more RVRs values are reported. They can be put into METAR format in ATIS and I haven't seen one particular standard. It can be as simple as "RVR 500/700/300" (with the first being TDZ, then MID and RO). When the weather is down to CAT-3 (or even CAT-2) minimums and 2-3 RVR values are required and being reported, they are usually being reported verbally by the Tower. The reports can be provided as often as every 10-15 seconds and rarely go longer than a minute without an update. This is due to the fact that reports below minimums on CAT-3 approaches even after established on final require a go-around prior to alert height. It's not realistic to expect a crew on an approach to be constantly checking ATIS for new RVR information that could be changing rapidly.
Originally Posted by
MarkVI
Additionally, if all three positions are operating, I would assume that if one of the positions reported less than minimums I'd not be able to takeoff -- if that same unit were offline and not reporting this wouldn't matter -- correct?
Correct on both statements.