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Why have ILS X / ILS Y / ILS Z ? (and which IAP types are missing in GPSs)

I don’t think the NDB (BZ) to ILS for Brize (EGVN) has the Cat A/B procedure in the database – only the Cat C for some reason – certainly that seems to be the case with our Garmin430s. Question – could you elect to fly a Cat C procedure in a lower Cat aircraft? By clearance with ATC?

Now retired from forums best wishes

Timothy wrote:

Do you mean those in the States or worldwide? I know that the FAA are opposing the RNP designation, but it is going to become very widespread in Europe and the rest of the world and is supposed to be mandatory by 2024, so does that mean that Jepp DBs won’t have any RNAV approaches because they are all designated RNP?

I had heard that this was just a problem for Boeing but that may just be hearsay.

Hmm. We spent some time on this when preparing the talk for AERO 2018, and I could have sworn that you were part of the conversation, but perhaps you were busy with other things.

Approaches meeting the RNP APCH specification will be in the database but retrievable as RNAV XX GPS

Approaches meeting the RNP AR APCH specification will not be in the database for most of us — they never have been. In those aircraft whose FMSs are capable of RNP AR APCH, they will be retrievable as RNAV RNP XX.

The labelling is not just a problem for Boeing, but also the other manufacturers. Boeing and Airbus sent a rather stroppy “we’re not playing along” joint letter to Montreal, and Garmin are in the same boat. The label used to identify the approach is not simply a string in the nav database, but is generated based on the approach metadata.

The chart names in the US will remain RNAV (GPS) and RNAV (RNP) for the RNP APCH and RNP AR APCH Nav specifications respectively.

KUZA, United States
I could have sworn that you were part of the conversation

No, I stayed out of Friedrichshafen this year, if you remember.

But what you have written is as we have documented in Edition 3, which will be winging its way to you very shortly. Just one page of index to go.

Balliol, many approaches are missing from the database. I would have no hesitation using the C

EGKB Biggin Hill

Lydd EGMD RNP Y or RNP Z and why Y not in Foreflight database

The other day I did a local flight and as I often do I asked for an IAP at the airport down the road – Lydd EGMD.

The ILS was INOP (wrong kind of water – to use a phrase familiar to seasoned Brits )

Now of course I can’t reproduce this!!

FF has had its multi-gigabyte database update since then, unfortunately.

But the KLN94 did the same. It showed only one RNP for 21. I didn’t get a photo but it was called just RNP21 with no Y or Z. That is the 2 Nov 2023 ARINC cycle. I am sure I can reproduce this bit.

What is causing this? I know FF sometimes refuses to “send to map” procedures whose plates are expired (a procedure, no pun intended, which I regard as unsafe) but …

Lydd ATC were a bit puzzled but of course Y and Z are basically the same…

Administrator
Shoreham EGKA, United Kingdom

Is it just my few sporadic visits but the ILS tends to be off a lot there.

The NDB seems to be much more reliable

Peter wrote:

But the KLN94 did the same. It showed only one RNP for 21. I didn’t get a photo but it was called just RNP21 with no Y or Z. That is the 2 Nov 2023 ARINC cycle. I am sure I can reproduce this bit.

Peter, which IAF it shows on KLN? If it is SORDI then it is Y, LONRU – Z.
Although, I’m puzzled too…

EGTR

I got LONRU – Z

The Y was not in the FF database and not in the KLN94 database.

Administrator
Shoreham EGKA, United Kingdom

Is there any consistency in the CAA identification of RNP plates?
In the States they are, I believe, listed in logical reverse sequence in order of Category I.e. Z for Cat A & B; Y for C and so on. etc. Thus making it easier to select the right plate (especially in a hurry) without having to peruse it first.
At Lydd, the Cat A & B is identified as Y.

Last Edited by Peter_G at 16 Nov 13:35
Rochester, UK, United Kingdom

That’s funny… nobody mentioned that here.

But what would be the motivation behind a device or application suppressing one or other of these?

MDA for Z is 610ft and for Y it is 440ft.

Administrator
Shoreham EGKA, United Kingdom
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