Which transmissometer measures the RVR value specified in the takeoff limits section? TDZ? MID? Or Rollout (RO)? If there are 3 transmissometers for the runway at an airport, which transmissometer measures the RVR values specified as in the example given below? Or is it the average of all? (TDZ, MID, Rollout). enter image description here

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    $\begingroup$ Apart from averaging them, one could also conceivably take the minimum RVR of the three (which would IMHO make the most sense, in that you might need the entire runway length in an RTO and having any part of the rwy covered in fog would be unsafe). $\endgroup$
    – TooTea
    Commented Feb 2, 2023 at 11:40
  • $\begingroup$ This seems to be the value reported by ATC, which itself can be determined according to criteria explained in JO 7110.65 section 8, in particular: "When two or more RVR systems serve the runway in use, report the indicated values for the different systems in terms of touchdown, mid, and rollout as appropriate" $\endgroup$
    – mins
    Commented Jun 23, 2023 at 14:16


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