YSSY - ILS Z or ILS Y PRM 16R?
 

All….

Scratching my head on this one:

We were cleared the ILS 16R PRM into YSSY recently. There are two approaches into 16R using PRM…. a Z and Y.

We asked which one they'd like us to use and they again stated, "ILS PRM 16R". Asked yet again since we could not determine if they wanted us to use the Z or Y procedure. We were told to standby. Then told it would be ILS PRM Z 16R.

I do know the "Z" is always the preferred approach but my question to you all is….

In the absence of a designator such as Y or Z for an approach, are we to fly the "Z" procedure? And if so, would anyone have a reference for this somewhere?

Thanks

Kap

Z uses IKS DME, Y uses SY DME but the approaches are the same other than this. Nothing written in AIP that I could see so I guess it is up to the preference of the crew as to which fix they wish to use for a glide slope check.

If you're cleared an ILS without specifying which should be used then you have the option of either. For the 767, we'd normally go the Y due to instrument switching but if the SY DME is U/S then the Z is easily doable.

Apparently (rumour network!) the SY VOR and DME will be decommissioned once all six ILS's at Sydney have discrete DME frequencies. Then the problem will go away.

In any case, I find it helpful to remember that the sole purpose of a DME on an ILS is to provide a glideslope integrity check. Which particular navigation device is used to achieve this goal is unimportant. Could even use the GPS, if national law permitted it.

Not entirely true Oktas8, the SY VOR will be decommissioned from mid-2014, however the SY DME will be relocated 180m from its present position. The reason for the DME remaining serviceable was due to performance limitations of some operators with older machinery.

Lol.... Seriously???

There is no difference between the two barring which DME you use... As the controller said he's cleared you for the approach... It's left to you which you want to do... You'll only be forced to use one if either DME is u/s at a certain time..

Yes Biatch, I imagine he does mean it seriously. Its a perfectly valid question.

Why? Because in other parts of the world (read most/all of the others), you would be specifically cleared for the Y or Z approach, because they are different approaches.

MEL, SYD and BNE there happens to be no issue, as the only change between the charts is the use of ILS vs Airport DME (although why Brisbane is the opposite to SYD and MEL is beyond me). But in many cases that is not the only change between a Y and a Z approach. There could be different minima, a different missed approach, any number of things. They are, again, different approaches.

Its a relevant question for someone who doesn't do Australian airports day in, day out.

SY VOR is being decommissioned permanently


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OK…..

Thanks for all the replies.

Let me know tell you "the rest of the story":

After landing, and on ground control freq, the ground guy said to us, "no worries on this but approach control would like you to contact them". I said ok will do.

Had the other guy monitor ground while I went over to approach freq. This controller said he just wanted to clear up any confusion. So I said that I just needed to confirm which approach of the two options he wanted us to fly and initially had not given us that information… that was all. Since we were told to fly the "Z" procedure, he then asked what the dates were for our approach plates. I told him and then his reply was, "OK, you flew the right approach then".

And that was it.

So….. the fact that he said we flew the right approach left me even more confused… and thus the question if we were supposed to know to fly the "Z" if they don't give a specific approach procedure as the "Z" is the primary/preferred approach.

I think pretty much every pilot here would have at least queried ATC on which of the two procedures ATC wanted him to fly just to confirm….and I was simply making sure I was doing the right thing.

Kap

Don't be such a Biatch, Biatch.

We have company notams for a couple of ports around Asia for the Airbus fleet advising the crew that the FM database ILS is coded for Y or Z. Just so we can match up the waypoints to the correct chart.

Other than that it's up to you which one you chose to fly as the initial approach and missed approach are generally the same..

HOWEVER some Japanese ports ( and maybe others ) clearly specify on the ATIS which ILS they want you to fly as some of the procedure is different.

"Expect ILS Y 16R, using Runway 16R....." Is usually what you hear on the ATIS.

Incorrect. Pretty much every pilot here would have known that you can fly either approach. Your choice.

Yeh as already stated, it doesnt matter which one you fly, the only difference is which DME you hold/use. The geographic points dont change, just the point from which you measure the distance from does.
Your choice. Same at Wagga, Melbourne and prob plenty more around the place.

With reference to the approach controller stating "you flew the correct approach", vaguely remember the chart index number changing few months back as 16R ILS got its own paired DME. I may be incorrect... He was prob just referring to that.

I'm with Defred. I've never queried, and have never heard another pilot query, which ILS, the Y or the Z, to do. You just pick the one appropriate to your DME fit/desire.

If in the future the X and Y procedures are different (as Nitpicker is alluding to overseas) I'm sure ATC will clear us to do the one they want us to do.

Why do you think they would care whether you were using IKS or the SY DME?

I would say his answer was tongue in cheek. He was saying, in effect, that provided your chart was current, it didn't matter which of the two you used - both were correct.

It is a reasonable question and anytime your not sure you should ask as I would and in my opinion any intelligent person would. ATC are capable of making errors as are pilots.

Having said that I would normally search for differences between the ILS's and if they were minor as they are in this case (different DME) I would have made my own mind up.

The aircraft data base is normally predicated on using a particular DME and that makes the decision easy for you, all though you may not discover the difference until you cross check the altitudes etc. (been there done that more than once)

The OP has asked for an AIP reference for his question, and as far as I can see no one has found one (me included). Can anyone find a reference anywhere? I can only recall (don't have the AIP to hand) mentioning of the naming convention used, when this was introduced in Australia a while back, possibly in a now expired AIC or SUP.

Is this another example of our awesome regulations in Australia - folklore and local familiarity begets procedure that turn into proxy regulation (ie. the only difference is the DME, so if Approach don't specify, you can do whatever you want... [drawl] "Yeah that's just what we've always done, it must be right"[/drawl].)

As for those saying "the only difference is which DME" well I think you're missing the point somewhat. That may apply in this specific case, but I reckon it's fair to say that the OP is looking for a more general answer, that could be applied in all cases.

And if there's any doubt, of course without exception, you would ask!

Counter-Rotation:

Thanks and you nailed it right on the head as to what I am seeking with my post!!

I can not find anything in my company manuals or other international documents to answer my query.

K

Maybe I can help clear this up....maybe I cannot.

There are 2 issues here. 1. Approach naming and 2. Approach clearances.

1. Approach naming - There was a change to this a few years back and the current ICAO convention is to name the approach according to the navigation aid or system that is providing AZIMUTH guidance. This is why all the DME's were removed form the approach names. Of course the issue that will be arising in the near future is what do you name an approach that starts as an RNAV/RNP and ends in an ILS.....ICAO are still sorting that one out.
Part b to this was that someone declared (and I think it was CASA) that if there are 2 DME's available for a particular approach, then we would have to provide a separate approach for each DME. This is where the ILS-Z/Y's are coming from. My thoughts are that the intent of the Y/Z suffix was to depict approaches that gave separate tracking...like a timed reversal vs a DME reversal or 2 distinct inbound tracks. The result is that we are publishing 2 ILS approaches that are exactly the same on 2 different plates. This is further complicated by PRM...so you have ILS-Z/Y and PRM-Z/Y

2. Approach clearances. Up until a few months back I was told that the approach clearance had to contain the approach title when it was issued. With recent questions to ATC we have become aware that, in the case of Sydney at least, for ILS approaches they just say "Cleared ILS approach". They do this for a few reasons but the main one is that they just don't give a rats which one you fly. If your ILS or PRM clearance does not contain the suffix Z or Y then it is up to you. If you look at the AIP GEN 3.4-45. There is a note in the left column. "...the procedure suffix may be omitted when no possibility of confusion exists." so no-one is breaking any rules here....its just more complicated than it needs to be.

This scenario is being further complicated with the introduction of CAT II/III minima and the insistence that these also be published on separate plates (ie YMML)

The future...CASA has been approached with a solution, which a safety case is currently being compiled for. The proposal is to publish 1 ILS plate, and provide refences to the 2 DME's on it. Provided we can keep it simple I think it would work and we are aware that this is done in overseas locations.

Hope I have answered some questions.

Alpha