YSSY Vis App by night

[1224]

Does anybody know why, when doing a visual approach by night at YSSY with the aid of the ILS, the distance you may start descent below MSA/MDA for RWYS 16L and 34L, is 14NM rather than the usual 10NM?

[SM4 Pirate]

Because Sydney is Special?

-- within the prescribed circling area for the category of aircraft or a higher category, where the limitations of the higher category are complied with, and the aerodrome is in sight; or
-- within 5NM (7NM for a runway equipped with an ILS) of the aerodrome, aligned with the runway centreline and established not below “on slope” on the T-VASIS or PAPI; or
-- within 10NM (14NM for Runways 16L and 34L at Sydney) of the aerodrome, established not below the ILS glide path with less than full scale azimuth deflection.

It's probably something to do with the 'integrity of the surveyed area' and the lack of high obstacles from 10-14NM?

[Bort Simpson]

I'm not 100% sure on the accuracy of this answer but it has a lot to do with the rwys you mentioned (16L and 34L) having their thresholds further towards the centre of the feild than their parrallel counter parts. I.e. 34L threshold is further north than 34R. Similarly, 16L threshold is further south than 16R threshold (a good bit further). So why the longer vis approach? Well this means when ATC get you to come around to join final for these runways you'll be further out from the Left runways in comparison to the Right runways. I belive it has been surveyed out to that distance but I could be wrong. Where as on final for the R rwys, you'll be closer to the threshold and, either you shouldn't need the extra vis or these runways havn't been surveyed out that far?

Sorry, not a 100% definative answer however it should give you a good idea and start for looking into it further.

[Capt Fathom]

The ILS Approaches for 16L 34L commence at 4000', 13nm from touchdown.

So for separation purposes, the approaches start at 3000' for 16R, 4000' for 16L, and 3000' for 34R, 4000' for 34L.

To allow simultaneous independent visual approaches to occur, you need to be able to conduct a visual approach from 4000' when on the Left Runways.

That equates to a distance of about 13nm when on the GS.

Then again, it may have nothing to do with it, and I just made it all up. :E