Hello all -
I am confused about the approach plate for the GNSS arrival at COOMA. If the aerodrome ele is 3106, how can the GNSS approach Minima be 1444 ?

I can't see where you are getting 1444 from. The MDA on the current chart is 4250 for all sectors. Can you explain how you arrived at 1444.

Bob

Hi Bob -- Thanks for getting back to me so promptly. I have only recently started to study for the IREX exam - so I'm pretty new to all this. I'm looking at the GNSS approach plate for RWY 18 that I obtained from Airservices webpage - current AIP edition 25 MAY 2017. I'm looking at the bottom section - Category ABC etc .. where the Alternate Minima is located. The Alternate (grey shaded) states (1544 - 4.4). Seeing that COOMA has an AWIS, I subtracted 100 feet and got 1444.
Thanks - Robert.

As part of one's studies, one really needs to read ALL the AIP documentation lest you be caught out by the bits and pieces which are hidden here and there ..

Try going to the URL page where you hyperlinked to aerodromes and procedures charts but, this time, hyperlink to legend info and tables. Now, select Legend No. 5 and you will end up at the following detail -




You will see, now, that the 1544 you cited is a ceiling reference. A quick look at the AIP definitions and one sees that ceiling is a height, rather than an elevation.

A further clue was on the plate .. the line cited is labelled "alternate minima" rather than approach minima .. the lines above relate to the approach.

Stick with it and you'll win just fine .. we were all thoroughly confused by it all when we started out in this aviation game ...

Hi John / Bob -- Thanks for your reply ! On reflection, I did not state the initial question well at all. My question was in regard to the Alternate Minima not the approach or MDA altitude. After reading your responses, I decided to go back and re-visit Bob's text in the Instrument Rating Study Guide, thinking that I must have missed something in my study. I discovered that the Minimum Alternate heights on the approach plates are AGL - that was the problem. I could not understand why the Cooma Minimum Alternate was 1444 and the aerodrome level AMSL was 3106. I now know that the plates and the TAF's stating cloud cover are stated in AGL not AMSL so --- the light came on !
Thanks and regards to you both -
Robert.

All heights in brackets are AGL.