ILS Question

[CharlieLimaX-Ray]

Whats the difference between ILS approach charts, ILS-Y YSSY (Jepp 11-1) RWY 07 and the ILS-Z RWY 07 (Jepp 11-2).

[Mach E Avelli]

Only the note on one that GPS can be used in lieu of DME. But why bother with two otherwise apparently identical charts beats me. Perhaps someone more knowledgeable in this area could enlighten us?

[SM227]

I believe it that the difference is the navaid used for distance, for example, an aircraft without a dme can do a LOC approach using GPS in lue of DME because the distance is referenced from a waypoint (VOR, etc.) allowing you to put that into the GPS for distace readouts, I dont think you can leagaly select the location of the GS transmitter in your GPS (if it even has it in the database, im yet to have seen it).

[Dragun]

From memory I'm pretty sure it's simply that one uses the SY DME and the other uses the ILS DME.

[ITCZ]

one uses the SY DME and the other uses the ILS DME.
Yes, thats the difference.

The SY dme and the ISY dme are in different locations, 0.7nm apart. So the altitude/distance scales and the dme fixes are different.

Eg GLF is 9.8 dme ISY, 10.5 dme SY.

Ergo, two charts.

As SM227 points out you can only use GPS in lieu of DME on ILS-Y because that chart says so, and gives the GPS reference as SY VOR, because it is collocated with SY dme. There is no similar instruction on the -Z chart because ISY dme or collocated navaid/waypoint is not available for selection from your GPS nav database.

[CharlieLimaX-Ray]

Thank you for that gentlemen, I thought that would be the reason for the two charts and there was an AIC issued from memory.

[Stationair8]

ITCZ, is on the money.

[Dog One]

NDB Charts with an A indicate that the approach is a circling approach only.

[Capn Bloggs]

The approach chart notes also provide a clue: 11-1 uses the SY DME for the LLZ approach, whereas 11-2 uses the ISY DME for the LLZ approach (I realise you are doing the ILS).