GPS substitution for navaids - Europe generally - is it allowed? (and low vis ops)

Airborne_Again wrote:

In principle the difference could be due to different software versions, but I think it is more likely that the installation approvals are what the manufacturer asked for (i.e. needed to provide evidence for) and/or what the particular competent authority agreed to approve.

In the case of Cessna it is the FAA that approved the POH so it is the FAA that would have to be convinced. In the case of Diamond it is EASA or the Austrian competent authority. Recall what I wrote in an earlier post that European authorities used to be reluctant to give RNAV/RNP-1 installation approvals.

An upgrade for the DA40 would most likely be a paper-only exercise but it could cost a lot in money and effort.

AC 90-100A describes the requirements for U.S. Terminal and En Route Area Navigation (RNAV) Operations. Usually the AFMS will include the approvals, but many AFMS pre-date the advent of PBN and various RNAV/RNP type specifications. The FAA dealt with this by publishing a spreadsheet and later replaced by a pdf document of a FAA AC 90-100A Compliance Matrix local copy. This only applies to FAA land, but the G1000 and GNS430/530 legacy equipment is approved for RNAV 1 as well as DME/ADF/VOR substitution. The compliance list is by vendor.

Peter wrote:

That suggests that the ability of US pilots to remove the ADF or the DME is based on

not many NDBs around anymore
not many IAPs being “DME mandatory”
lots of overlay approaches, or GPS approaches
Europe fails on all three.

US is eliminating most NDB and reducing VOR by about a third.
Many IAP require DME, but GPS substitution is allowed for all but about two weird DME arc approaches (not able to be coded in database) where the DME is used for lateral guidance on the final approach segment.
Virtually no overlay approaches exist, not sure I could find one.
Only 37 GPS stand alone approaches exist in the US.
At airports where VOR (1741) or NDB (391) approaches still exist, there are RNAV (GPS) procedures (16,456) .

NCYankee wrote:

If this were a US regulation, I read the “or RNP APPR” as an alternative.

Well quite. Is there a regulator for whom “A, B, C or D” does not mean “A or B or C or D”?

Were I to speculate on the intention of the author, I would think that she wanted to exclude GPS navigators installed purely on a no-hazard-no-credit basis for VFR use only.

NCYankee wrote:

Virtually no overlay approaches exist, not sure I could find one.

In the early days of the overlay program (when EASA was still a twinkle in its daddy’s eye) I think the FAA went through and suffixed every conventional non-precision approach with “or GPS” if it met certain fairly permissive criteria. If there are none left, I guess it’s because they’ve all been redesigned as stand alone.

NCYankee wrote:

Only 37 GPS stand alone approaches exist in the US.

What’s a GPS approach that is not RNAV (GPS)? Is it just an old label or is there a technical difference? Any examples please?

Peter wrote:

It was the convoluted language I could not work out. When is this applicable?

You mean the 150 m or 400 m requirement? The current EASA minimum without an LVTO approval is 400 m. It’s reasonable to ask the legal basis, I guess. Take-off operations in visibilities of less than 400 m are defined to be Low Visibility Operations and LVO need an approval. SPA.LVO.100 requires an operational approval for LVO.

The 400 m minimum is applicable to visibility, but one could argue that the 400 m is only “enforceable” when RVR is measured and reported, as it can be determined by the pilot unless an RVR is measured and reported

AMC1 CAT.OP.MPA.110 Aerodrome operating minima
TAKE-OFF OPERATIONS — AEROPLANES
(a) …
(3) When the reported meteorological visibility (VIS) is below that required for take-off and RVR is not reported, a take-off should only be commenced if the commander can determine that the visibility along the take-off runway is equal to or better than the required minimum.
(4) When no reported meteorological visibility or RVR is available, a take-off should only be commenced if the commander can determine that the visibility along the take-off runway is equal to or better than the required minimum.

Jacko wrote:

Perhaps I’m missing something obvious, but I still don’t see where that (arbitrary?) minimum RVR of 150 m came from, unless it’s just regulation for the sake of regulating.

It was the minimum under national law in the UK, and France, I think, for non EU-OPS operations prior to the introduction of the EASA Air Ops regulation. So there’re precedent. The task of persuading regulators that NCO is capable of operating safety at major airports in RVR 150 is hard enough. I wouldn’t fancy putting the case for RVR 0.

NCO.OP.110 Aerodrome operating minima – aeroplanes and helicopters
Regulation (EU) No 379/2014
(a) For instrument flight rules (IFR) flights, the pilot-in-command shall select and use aerodrome operating minima for each departure, destination and alternate aerodrome. Such minima shall:
(1) not be lower than those established by the State in which the aerodrome is located, except when specifically approved by that State; and
(2) when undertaking low visibility operations, be approved by the competent authority in accordance with Annex V (Part-SPA), Subpart E to Regulation (EU) No 965/2012.

AMC1 NCO.OP.110 Aerodrome operating minima – aeroplanes and helicopters

TAKE-OFF OPERATIONS
(a) General:
ED Decision 2014/016/R
AMC1 NCO.OP.110 Aerodrome operating minima – aeroplanes and helicopters
(1) Take-off minima should be expressed as visibility (VIS) or runway visual range (RVR) limits, taking into account all relevant factors for each aerodrome planned to be used and aircraft characteristics. Where there is a specific need to see and avoid obstacles on departure and/or for a forced landing, additional conditions, e.g. ceiling, it should be specified.
(2) When the reported meteorological visibility is below that required for take-off and RVR is not reported, a take-off should only be commenced if the pilot-in-command can determine that the visibility along the take-off runway/area is equal to or better than the required minimum.
(3) When no reported meteorological visibility or RVR is available, a take-off should only be commenced if the pilot-in-command can determine that the RVR/VIS along the take-off runway/area is equal to or better than the required minimum.
(b) Visual reference:
(1) The take-off minima should be selected to ensure sufficient guidance to control the aircraft in the event of both a rejected take-off in adverse circumstances and a continued take-off after failure of the critical engine.
(2) For night operations, ground lights should be available to illuminate the runway/final approach and take-off area (FATO) and any obstacles.

Example: AIP AUSTRIA AD LOWG: 5.1.3.
Low visibility take-off
5.1.3.1. A low visibility take-off is given when the Runway Visual Range (RVR) is less than 400 M.

So the limit is 400m for NCO, correct?

bookworm wrote:

I wouldn’t fancy putting the case for RVR 0

I am sure if RVR goes to zero, I will protest against the limitation on my C2 medical (now I wear corrective spectacles and carry spare ones )

So there’re precedent. The task of persuading regulators that NCO is capable of operating safety at major airports in RVR 150 is hard enough. I wouldn’t fancy putting the case for RVR 0.

Did the regulators consider the common situation in which an aeroplane is operating from the top of a drumlin pasture? (In that case there is no defined runway and no obstacle so it doesn’t matter a damn which way we take off – and thanks to the steep slope in every direction, we’re off the ground within a couple of chains).

Well, I guess not. Our regulators must be lawyers who have never flown a light aeroplane, let alone from a drumlin silage field or a sand-flat. They know perfectly well that a teenager in a crappy old Cessna 150 can take off in 126 feet (Valdez, 2017), but they imagine that it’s necessary to see four times that length of tarmac even when flying a somewhat sprightly aeroplane.

These lawyers know precisely that many of us (not only Pitts drivers) can’t see any of their precious white centreline markers or any other part of the runway ahead when we’re lined up for take off under a clear blue sky, yet they’ve managed to persuade each other that if we can’t see 500 ft of runway in IMC we’re all sure to die.

I give up… The EASAholes have won… They still want to drown all of GA with rules made for commercial air transport, bizjets and fancy aeroplanes which need runways.

Snoopy wrote:

So the limit is 400m for NCO, correct?

Indeed it is unless you have an LVO approval, but that is unrelated to the airport low visibility procedure mentioned in the LOWG AIP entry. Airport LVPs are something different and airports can apply them at higher RVRs than 400m.

The restriction to 400 m is actually not in part-NCO itself but in part-SPA (SPA.LVO….). It is referenced by NCO.OP.110(a)(2) which you quote.