On this day, I was on a REX flight into Adelaide (as a passenger). As we came down the ILS onto 23, Edinburgh was clear, Parafield was clear, the city centre was clear, got within less than 5nm (not 100% on the distance - but we were certainly abeam or passed the city centre, so closer to runway) from the threshold and went into fog. From the pax window I couldn't see horizontally or directly down.
Pilot did a standard missed approach, and off we wandered to Whyalla for fuel, where there was quite a little REX gathering of diverted planes.
I too was curious why Edinburgh couldn't be used as an alternate? Don't the RAAF boys like to share? (The ILS at Edinburgh runs N to S, same as Adelaide).