Peter wrote:
In the US, you can subst a GPS only for a part of the IAP, not all the way down to MDA. @ncyankee will know the latest.
With FAA, you can use GPS for navigation except for the final approach segment of a VOR or NDB approach, but if the Nav facility is operating and course alignment is monitored using a VOR/ADF receiver, the GPS may be used for navigation on the final approach segment. I flew this VOR approach using GPS and was monitoring the VOR course with the bearing pointer. This procedure was the VOR A at KFLO, I wanted to practice a DME arc with a VOR approach and did not switch the Nav source from GPS to VLOC when on final, just monitored the bearing pointer. With the current version of the GTN 750Xi software, using this technique would have provided me with +V advisory vertical guidance if the VOR procedure had been straight in to a runway.,
The approach ban being 550m is probably the most useful, because ATC monitor this and are required to report pilots going past the FAF/1000ft point if RVR is below whatever.
Kindly provide a source for this statement. I have never heard of this, ever, by anyone. Is this another strictly UK thing?
I have it directly from somebody in ATC. I am pretty sure I recall who it was but I am not in a position to post it 
Yes it was a UK source, but isn’t the approach ban a strict legal requirement everywhere? More to the point, it is obviously very visible – this being relevant.
We could ask the ATCOs here (and it is 100% sure that every European CAA will be reading this thread) but on past record they are extremely reluctant to post on confidential procedural matters.
Its not confidential. There is an ICAO and an EASA rule regarding 550m visibility or any other visibility and when you can start or continue an approach.
The 550m RVR is given by ATC to the pilot. Itbis up to the pilot to make a decision what to do with that information.
However if you ignore the rules in that decision you have committed an infraction. ATC are duty bound to record that in case of a incident. What the NAA does with that information is up to the NAA.
ATC are duty bound to record that in case of a incident.
My info is that they are duty bound to report it “up some channel”. Whether this results in the pilot getting busted I don’t know but I have always been told that you must go around unless it is a mayday. Whereas busting the DH cannot be actioned even if it is obvious.
Let’s see what other pilots say 
This just doesn’t make sense. ATC provides real-time RVR. If below mins, approach ban is in place. Why would someone go below the approach ban ALT when ATC just relayed a currently below min RVR? And, once below the ban ALT, the RVR could go to zero with no effects. We are, obviously, only talking controlled airports here, and 99,9% of such transmissions will be between heavy metal and ATC, not between the latter and a DA40 or similar…
Assuming someone does fly the approach, do you think ATC has nothing better to do than request the OPS Spec and see if the operator is e.g. qualified for CATII/III?
At uncontrolled fields, some people do whatever they want to anyway, no matter the regulations.
Peter wrote:
Yes it was a UK source, but isn’t the approach ban a strict legal requirement everywhere? More to the point, it is obviously very visible – this being relevant.
The question, really, is how ATC would know exactly what VIS/RVR minimum applies to a particular flight. Under the (EASA) regulations in force up to today that depends on a lot of factors which are unknown or not readily known to ATC. This includes the (M)DH. So if you are cleared for an RNP approach, the VIS/RVR minima will depend on whether you fly an LPV or LNAV/VNAV or LNAV – and in the latter case if you fly CDFA or not – none of which ATC can know. They could possibly guess by looking up the equipment part of your flight plan to see if you have SBAS, but I really don’t think they bother. Worse, in the old regs the “applicable” VIS/RVR minima were described in a GM and not even an AMC, much less an actual implementing rule!
Even with the new regulations the problem remains for CAT flights which do not have the “blanket” 550 m RVR minimum. The “approach ban” rule for CAT still talks about “the applicable minimum”.
Not specific to N-Reg, but at least now we can ditch the ADF. DME still not quite.
The question, really, is how ATC would know exactly what VIS/RVR minimum applies to a particular flight
This is also operator specific to each comercial operator, so ATC can’t enforce it on each flight? when ATC has a doubt they do report to CAA for both private and comercial operators which is healthy IMHO…
When you arrive at an airport do you not state the approach you wish.
On the approach plates there is a minimum visibility/RVR quoted.
ATC gives you the RVR.
IIRC you can’t start the approach without or is it descend below 1000ft on the Final approach if the RVR or extrapolated visibility?
The ATCO fills in the boxes on his crib sheet with the details of the flight RVR etc, or maybe nowadays it is simply recorded.
Whether, if the ATCO gives you an RVR of 400m and you start the approach,anyway, the ATCO puts you in an infringement pile I don’t know. I very much doubt it. But it is noted as I believe all flights are. Of course at non controlled or untowered airfields,as @Snoopy says no one would ever know. But in the case of accident there would be a lot of witnesses saying they couldn’t even see the plane until it landed.🙂
The same rules apply to an N reg or G reg in France as one has to fly to the most restrictive of the regulations between country overflown, country of registration, and country of pilot’s licence..
