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machman777
17th Feb 2007, 12:43
Jepp Charts show RVR, RVR & vis or just a Vis on the minimum for ILS approaches.
What dictates which value/ values are shown?:)

flyboyike
17th Feb 2007, 16:08
If an airport has an RVR reporting system, the chart will show both Vis and RVR. If it doesn't, only the vis will be shown.

machman777
17th Feb 2007, 22:46
Thanks for the reply Flyboyike.

I have re read JEPPS INTRODUCTION page 114 which states " RVR visibility values are chartered only when the value is not the same as the prevailing or meteorological visibility value. When a difference occurs, the respective RVR and prevailing or meteorological visibility values are prefixed with "RVR" and "VIS". When there is no difference, the minimum is shown only once and means either RVR (if RVR is reported for that runway) or visibility if measured otherwise".

This partially answers my question, but from the above paragraph, wouldn't the "prevailing or meteoroligical visibility" always be different to the RVR, as the visibility is the slant range, wheras RVR is measured horizontally along the runway?

For an example there are aerodromes in Asia, where all of the aerodromes below have 3 transmissometers (Touchdown, midpoint, and rollout) where aerodrome 1 has only RVR's given, aerodrome 2 has RVR & Vis, aerodrome 3has 1200m only, aerodrome 4 has RVR and Vis for one runway & a figure of 900 m for the reciprocal runway which is 3 degrees offset for the ILS.

mutley320
18th Feb 2007, 23:01
Have a look at the Jar ops section allowing you to convert Met Vis to RVR if you have certain lighting elements in operation. Depends if you are operating day/night. RVR always takes precedence but this gets you out of jail if it breaks down and you can only get a met vis and your minima are written reference RVR.
Not allowed for take off minima or CAT 2/3.