So I was wondering if the RVR at an airport is reported above CAT I conditions for eg 1400 Meters etc but the Visibility is 50 to 100 Meters then would the pilots carry out non instrument approach or would the approach would be carry out as per Low Visibility conditions ?

And what are the conditions for an airport to impliment Low Visibility conditions ?

  • 1
    $\begingroup$ skybrary.aero/index.php/Low_Visibility_Procedures_(LVP) $\endgroup$ Mar 9, 2021 at 11:12
  • $\begingroup$ You probably need to correct the use of the term "non instrument approach". $\endgroup$
    – skipper44
    Mar 9, 2021 at 23:14
  • $\begingroup$ If prevailing visibility is that different from the RVR at a runway, something is probably wildly off (i.e. one of the sensors is reporting inaccurately). Maybe an incredibly thick fog bank at the PV sensor but not at the runway, but that's rare. Almost always, RVR readouts are within +/- 1/4 SM (converting units, of course) of the reported visibility. $\endgroup$
    – Ralph J
    Mar 10, 2021 at 2:38

1 Answer 1


It is the RVR values that are used to determine the applicable minima.

The switch from normal to LVP Ops varies from airport to airport but the changeover process typically commences when the dropping vis approaches 1000mtr (say roughly 1200m) and is dropping so that the ILS Cat2/Cat3 LVP can be offered as the vis/rvr falls to below Cat1 requirements. More detailed info can be found in the country AIP and the same info would be spelt out in the Jepp or equivalent.

The Low Visibility info is specified in Sec 1.3 in the 10-1P series pages of the Jeppessen Terminal charts, ie "Airport Briefing" pages.


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