@superfly

Not really. Perhaps you're thinking of the fact that visibility above 1500m is normally not reported as RVR.

RVR can be reported only when measured by suitable equipment, and is given for a specific runway direction in the format RXX/XXXX.

Visibility, a more general all round assessment, can indeed be reported as such below 1500m (E.g. showing 0300 on my location's METAR right now - time for coffee!)



.

Wouldn't it be read equivalent to US CATI minimums?

e.g. RVR18 or 1/2sm VIS

If you have RVR reported, it controls over the VIS?

So in your example, if RVR wasn't reported you could shoot the approach with 800m vis? If RVR was reported you would need 550m?

That was my guess as well. You shoot the approach with 800m VIS or above if RVR is not reported. In the case of the RVR being reported then visibility should be 550m or >. Nobody seems to be certain though.

@ BOAC

This is a picture for the ILS approach at Bangalore for Runway 09. Notice how VIS (800m) and RVR (720m) is stated.

http://i1277.photobucket.com/albums/...psfdbd1182.jpg

Thanks, superfly - puzzling to me. In EU-land, where RVR is not 'available' EU-OPS gives us the option of 'converting' met vis to RVR (although there was always 'discussion' (never resolved) about whether loss of RVR barred a Cat I approach based on the wording in our OM).

I have to assume that the relevant Air regs do not allow this conversion. Again, in ideal conditions on a full instrument runway, in EU-land a met vis of 600m would suffice by day and 300m by night, so why 800m I know not.

I'm going to speculate that the 800m VIS is regarded as a state minimum, (perhaps by dint of being defined here in line with ICAO Cat 1 definition), but that Jepp have calculated the RVR upwards (from the AIP-published 550m) for some reason, and have charted both together. RVR (or vis without conversion) would then be the compulsory minimum. One possibility is that this is from an operator-tailored chart. Or maybe <speculate> in Jeppesen's estimation the AIP minima are too low and don't meet PANS-OPS requirements.</speculate>

(Per Jeppesen:)

Read this while reading on Auto land (Oxford).

The auto land weather requirement for a CAT I approach is : "Decision Height should be no lower than 200ft, and with either a visibility of no less than 800m or an RVR of no less than 550m."


So, my guess is when both RVR and VIS are stated on the approach plate. As long as you satisfy one of the two requirements you can continue the approach to land. So a few people who said it before I did were right. Again, I'm only guessing.

Any counter on this?

2. No prefix is charted if RVR/CMV and VIS is identical. The reported RVR is compulsory. If no RVR is reported, the VIS has to be used without conversion.

Hi justanotherflyer

Your reference to the Jeppesen charted minima above, can you please state the Jeppesen page reference?
I have had a look today and all I can find is this:

Quote" Visibility values in meters are labeled with an "m" while values in kilometers are labeled with a "km". When an RVR value is not equivalent to the associated meteorological visibility, both are shown and labeled "R" and "V".’ When RVR and MET VIS are equivalent, the visibility is shown once, ’and labeled as R/V, meaning either RVR or MET VIS"
Reference: Jeppesen manual. Introduction Tab. page: Approach 9.

Autobrake RTO

At least in FAA/NWS land, visibility and RVR are two different things. From the Federal Meteorological Handbook:

Prevailing visibility.

The runway visual range is the maximum distance at which the runway, or the specified lights or markers delineating it, can be seen from a position above a specified point on its center line. This value is normally determined by visibility sensors located alongside and higher than the center line of the runway. RVR is calculated from visibility, ambient light level, and runway light intensity.

So RVR is calculated for a specific runway while visibility is a general airport observation. Since the conditions at the end of the runway could be lower than the stated visibility, visibility mins are bumped up a bit to account for any variation from the airport observation. If you have a RVR report for a specific runway, it trumps the airport visibility report. If, for any reason, a RVR report for a specific runway is not available, you use the airport visibility.

Hi Autobrake

I took it not from the manual but from this Jeppesen briefing document (see p.23):

http://www.theairlinepilots.com/foru...psjeppesen.pdf

However to me that seems to be largely an amplification of your reference from the manual. On page Approach-10 in the manual, the Guide for Visibility Label Usage indicates that the labels V and VIS (similarly R and RVR) are equivalent - in my experience the labels VIS and RVR are generally used, notwithstanding the wording you quote from page 9.

On page 10 we also see:

....feeding my speculation in the Bangalore case (with apologies for this serious thread drift) that Jepp are quoting the VIS (800) as published by the State, but are recalculating the RVR upwards from the usual 550 for some reason (a more accurate derivation per PANS OPS criteria, perhaps?) also knowing that this more conservative RVR will trump the published VIS for their customers.

It would be nice to get some clarification on the question from Jeppesen themselves.

Let's stick with Bangalore - hypothetical scenario:

ILS R09: Met Vis 700m, RVR R09 1200m.

What to do, and why?

RVR/VIS
 

It's difficult for me, a retired pilot, to understand why all this confusion. We now fly $150 million dollar super jets and pilots have to put up with all this nonsense. Why can't it be simple like it was 40 years ago. Seems pretty stupid to me. Not sure I want to put me foot in an aircraft anymore. Looks like idiots running aviation now.

Me too, thermo, and so far no-one brave enough to answer my question!

I guess this is 'progress'?

Daft question: would an airfield not stop reporting VIS once it starts reporting RVR and vice versa? I should probably know that :(

Certainly in the UK met vis will be issued from MET (and on the METAR) and RVR from ATC so both would be 'in force' and presumably available.

Hi BOAC,
You may continue the approach because RVR (if reported) takes precedence.

thermostat:

Quote:

---

It's difficult for me, a retiredpilot, to understand why all this confusion. We now fly $150 million dollarsuper jets and pilots have to put up with all this nonsense. Why can't it besimple like it was 40 years ago. Seems pretty stupid to me. Not sure I want toput me foot in an aircraft anymore. Looks like idiots running aviation now.

---

You’ve had 40 years of substantial progress in technology.

You’ve also had 40 years of aviation bureaucrats thinking up more policies and schemes to justify building their big empires. Worst of all is ICAO, with its endless panels and meetings and “haromizations,” ad nauseum.

- have you a reference for that? I do not see it anywhere. Remember that a published MINIMUM met vis is a limit.

Like thermo, I feel this has got ridiculous and people should stop meddling with what WAS a very simple concept. RVR and CMV were perfectly fine, simple and easy to work with.

Hi BOAC,

The closest I can find is on page 108/109 of
http://www.easa.europa.eu/agency-mea...Regulation.pdf

"(c) Where the RVR is not available, RVR values may be derived by converting the reported visibility."
It basically says that if RVR is available - then use it, if it is not available then you may convert the VIS to RVR.

That's OK with a single minimum (ie RVR, when you can use CMV), but when you print both......................???