JAR-OPS RVR Minima for Take-Off (Jeppesen)

[320DRIVER]

Unless specified by an "R" or a "V", and unless multiple RVR values are required, to my understanding, the numerical value in the JAR-OPS Take-Off minima box on the Jeppesen runway charts can either be RVR or VIS.

RVR is pretty straigthforward, but for the case of VIS, is this the Tower VIS or that measured by an accredited observer at or near the runway threshold?

I could not deduce a clear cut answer from the Jeppesen glossary and preamble.

Due to the fact that the Tower VIS can be totally different than that at the runway threshold, doesn't it make operational sense that this VIS refers to that observed by a human observer at the runway threshold, even if the pilot's assesment is what really counts after all?

Thanks for any enlightenment :)

[Silky]

I think the answer is in the question... the fact that vis IS from the tower reported from objects of a know distance and RVR is at runway threshold at the height of a pilot in the flight deck at touch down.
So if a discrepancy occurs then they use which ever is relevant, RVR is normally only used when vis goes below CAT I, they then use RVR.
Now I'm sure different ATC authorities use it in different ways but this has been my exerience, maybe someone else will quote chapter and verse to help.... :) :) :)

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Gravity always wins....

[CHAPARRAL]

320DRIVER,
TRY THIS http://www.jaa.nl/jar/jar/jar/jar.ops.1.app.1.430.htm