As per the link I posted above, the vis is probably unenforceable unless there is RVR measuring equipment and official RVR is being reported.
The reason is that the tower staff usually has no way to know what the vis (or RVR) is along the runway.
I once departed in conditions where the tower could not see me at all; the cloud was about 30ft base and 200ft top and the tower was in IMC 
The vis below the cloud was ok.
I also did a departure in ~200m, maybe twice, years ago, not saying where of course. It is quite spooky because the picture ahead looks the same and then when you see 70kt IAS you rotate and immediately you see nothing.
Anyway, this is well off topic Have we actually got GPS substitution, or do the navaids need to be not notamed INOP and be identified?
For LVP ops I think the competent authority would expect the airport to have RVR measuring equipment.
I don’t think you can have GPS substitution for IAPs, not officially, anyway.
Even if visibility is reported and you don’t have the required takeoff visibility, one in theory can always ask ATC to taxi for a vibal but I guess if RVR is reported with LVP is in progress you are pretty much stuck on the ramp, maybe pushing you luck would be to request a walk to runway threshold with high-viz jacket and handheld radio ?
In UK airfields with no ATC and no VIS/RVR, you can always go but expect A/G operator to get very grumpy
For approaches it’s a different story…
The only thing is that under LVP in the past you could take off in vis down to 150m, and you needed the aircraft,operator and crew authorised if you wanted to reduce that further down to 75m, now you need the same authorisation for anything under 400m. So what would you Vibal?
The airfield is saying RVR is 100m, you taxi out and say oh no its 400m I count 6 balises, I’m taking off. I don’t suppose they could stop you but they might not want you back again. I think what you are talking about is eg an AFIS airfield which is not authorised for LVP. The question is, is anyone going to argue.
Its a similar argument to the real topic of this thread. The IAP calls for an NDB for the MAP , which usually means direct to the NDB and hold. would be very simple to substitute with GPS. Is it legal, probably not unless you also have an ADF on board. But as @Peter has often pointed out most new aircraft don’t even have an ADF so the authorities would be opening up a can of worms if they started prosecutions for this. But who knows, some authorities might like to beat up some of their pilots.
AeroPlus wrote:
I would find it interesting to know what the status is of the 150 meter versus 400 m RVR requirement at takeoff. Was this accepted?
Unfortunately it got strong pushback, mostly from the airlines, who feel that those who share aerodromes with them in low visibility should have training in such operations, particularly taxying. We also tried proposing more proportionate AMC/GM for NCO in order to get the SPA LVO approval. I don’t think that has been included in the AMC/GM with the Opinion (which is, in essence, just for information to the EASA Committee), but I think it will be considered.
gallois wrote:
AIUI the LVTO is declared by the airport when visibility is below 400m. On declaring it a set of procedures are put in place eg the fire brigade mobilise for each take off and landing and the number of take offs and landings are reduced/limited especially with ILS because objects traffic, animals, people etc might get in the way of the beam unseen by the tower.
An aircraft, suitably equipped, can take off in visibility down to 150m depending on the competent authority but not below, unless the flight crew are qualified.
It’s important to distinguish between Low Visibility Operations (including LVTO) and Low Visibility Procedures. LVO are approach/landing operations below 550 m RVR or LVTO below 400 m RVR. They require a specific approval under SPA.LVO.
LVPs are procedures put in place by the aerodrome intended to reduce the risk of LVO. Aerodromes decide when to put LVPs in place, often at much higher RVRs. Normal IFR operations (without an LVO approval) may take place when LVPs are in effect — other than complying with the procedures, there is no implication for aircraft operators. Conversely, LVO by CAT requires LVPs (or equivalent safety mitigations) to be in place.
As others have pointed out, the minimum RVR without a SPA.LVO approval has been 400m since the AirOps regulation took effect in 2016. Prior to that, in the UK and in France at least, NCC and NCO (which were not subject to the JAR-OPS1 or EU-OPS regulation) could take off in a minimum RVR of 150 m.
From here
Peter wrote:
I don’t think so.
Well, let’s agree to disagree then as regards certified RNAV equipment. It is different with tablets. NCO.IDE.A.100(a) makes clear that any equipment used to satisfy the requirements for navigation must be certified and a tablet is not.
The regs do not allow substitution of equipment carried.
That is not how EASA sees it. Anyway, that question will soon be moot as the new AMCs are explicit in what is allowed and what is not – including making it clear that if substitution is not allowed, you must at least “monitor raw data.”
Is this on some EU website?
Yes. It has also been discussed on EuroGA. The regulation changes have already been published, although they do not enter into force until October. The AMC/GM are not published yet, but the latest draft is here. Check pages 239-240.
any equipment used to satisfy the requirements for navigation
Yes; equipment carried.
That is not how EASA sees it
They are powerless to prescribe what you do in your cockpit.
including making it clear that if substitution is not allowed
That’s correct; substitution of equipment carried is not allowed, in Europe.
Like I say, EASA cannot mandate what you do in the cockpit, in private flying.
This discussion goes back many years – google for navigation using a tuna sandwich. @bookworm knows about it
Peter wrote:
That’s correct; substitution of equipment carried is not allowed, in Europe.
Obviously. But you’re implying that substitution of equipment not carried is allowed. Please provide some sources to back up that claim.
Like I say, EASA cannot mandate what you do in the cockpit, in private flying.
Of course they can. But they can’t enforce it. (Unless something turns up in an accident investigation.)
Everything not prohibited is permitted – subject to odd exceptions which don’t apply (such as public policy).
If you use some crazy method (like floating a rubber duck in a bucket of water and following the heading) it could get done for “endangerment” but it won’t be a criminal offence in itself.
So if you carry an ADF but actually use a tablet to fly the plane on an NDB approach, that is legal.
