Converting Visibility to RVR when planning

[learrocket]

According to JAR-OPS (not any specific OM) I have 3 statements. Please correct me if im wrong!
1, I’m planning a flight to a large international airport at night. Minimums for landing is RVR 550. In the TAF for the ETA (1hr before and 1 hr after) the weather says Vis 400. In this case I only need one alternate because I use the conversion factor RVR=VIS *2 (night and HI intensity approach lights)
2, I’m now flying to this airport and Im about to land and the tower reports VIS 400. Minimums RVR 550. They are not reporting RVR because the RVR equipment is U/S. I can now land because I use the conversion factor RVR=VIS *2 (night and HI intensity approach lights)
3, I’m out flying and going in to an airport that only has a VOR approach. The tower is reporting VIS 10km, Broken 300. Minimums for the VOR approach is, 2000ft and MDH 420 ft. The airport is at sea level. I can now land because ceiling is only for planning purposes in Non-precision approaches.
Thank you, and if you think I’m wrong please refer to a JAR document!!!

[fireflybob]

I can now land because ceiling is only for planning purposes in Non-precision approaches.


Yes, assuming you have the required visual reference not later than the MDA!

[learrocket]

But what about nr 1 & 2?

[learrocket]

I posted another thread before but did not get any answer. According to JAR-OPS can you convert visibility to RVR also in the planning stage???
Obviously you can do it when you are about to land (CAT I & Non-precsion approaches) but can you do it when planning a flight. (eg. for determening if an alternate is above minima)
Thnx

[RYR-738-JOCKEY]

RVR/vis conversion not on planning stage and not for Take-off min. And for the non-precision...If you do a circle-to-land then you better have ceiling above MDA., can't remember if it's a requirement, though.

[learrocket]

RVR/vis conversion not on planning stage and not for Take-off min.
I agree whith takeoff min but for planning? Where can you find this??? The JAR says that you can convert vis to RVR when landing but it does not say you can not do it in planning??? Or???

[learrocket]

1, I’m planning a flight to a large international airport at night. Minimums for landing is RVR 550. In the TAF for the ETA (1hr before and 1 hr after) the weather says Vis 400. In this case do I only need one alternate because I use the conversion factor RVR=VIS *2? (night and HI intensity approach lights)

Can anybody answer this?

[alberto86]

you usually use that calculation to make an idea of a possible RVR, but if it's not officially reported on the METAR/ATIS you cannot use it for landing decision.
I've always known that if (for CAT I ILS) you need RVR =/+ 550mt or 800mt VIS , and you're only given VIS=400mt, then you're supposed to continue the approach whilst still under the minimum, but then you must go around at the OM.
The general rule is that the most restrictive condition is the one that you must take account of.

Regarding the VOR approach, I've never known the ceiling is only for planning purpose. Anyway,why should that be? If you have BKN003 and the MDH is 420ft you will hardly be able to seethe runway land since you are at the minimum and have 120ft of clouds under you.So you cannot go lower than 420ft and should go around again...
Hope this helps your doubt:O

[learrocket]

you usually use that calculation to make an idea of a possible RVR, but if it's not officially reported on the METAR/ATIS you cannot use it for landing decision.

Offcourse not. I mean if the RVR equipment is U/S and the tower reports Visibility you can convert it to RVR and land!

I've always known that if (for CAT I ILS) you need RVR =/+ 550mt or 800mt VIS
Where can you find this? I looked in JAR but I cant find this?

and you're only given VIS=400mt, then you're supposed to continue the approach whilst still under the minimum, but then you must go around at the OM.
The general rule is that the most restrictive condition is the one that you must take account of.

Here I convert 400 times 2 (because I have night and HI intensity approach lights. Equals 800 meters RVR, so I can land!


Regarding the VOR approach, I've never known the ceiling is only for planning purpose. Anyway,why should that be? If you have BKN003 and the MDH is 420ft you will hardly be able to seethe runway land since you are at the minimum and have 120ft of clouds under you.So you cannot go lower than 420ft and should go around again...

Where do you find this? Yes Broken is a cieling but if I come in and they are reporting BKN003 its a big chance that I will not see the approach lights etc. but if I do I can land! Because the only controlling when Im in flight is the Visibility (RVR)!!!

[alberto86]

of course if you are at the minimum and see the runway or any of its references, you can land.
However I've never used or seen using the calculation you're talking about.
I'll go check the Jeppesen Introduction, I think there are all the answers to the questions you asked.
Regarding the ILS CAT I minimum, well, they are DH=200ft RVR=/+ 550mt or VIS=/+ 800mt and there's not doubt about it, it's in the introduction as well.
This means that, if you're copying a weather report or reading a weather bulletin reporting only a VIS value, that will be your reference.The same will be if only RVR is reported (pretty unusual...)

[learrocket]

Are you talking about JAR or FAA?

[alberto86]

I'm talking about JAR.., I've found and those informations on my ATP books and on the Jeppesen Introduction. It's a black book looking like a Jeppesen Airway manual.It usually comes with an Airway manual as well.

[learrocket]

Im sorry to say you are wrong. If you still think you are right you have to quote the JAR to prove me wrong.

Learrocket

[RYR-738-JOCKEY]

Alberto, the whole point of the Vis/RVR conversion table is for situations where only Vis is reported, you can convert it to RVR, provided you stick with the requirements of the table. So for a standard ILS Cat1, minima is 550 RVR, then if RVR equip U/S, you convert Vis to RVR, f.ex. 400 x 2 as above, and you land. However, if RVR is reported, you cannot convert the Vis and you have to apply reported RVR.