You forgot the emergency runway next to Tengah AND the additional (new) runway next to Changi which is military and NOT connected to the main airport. The RSAF actually uses the road next to Tengah once a year in a practice. The runway that is part of the East Coast Parkway near Changi has never been used to my knowledge.
I've never ventured out to the wilds of NW Singapore, so I didn't know about the Tengah emergency runway. I knew that the new runway at Changi East was military only, but I have read that it will be extended to become Changi's third runway.
I think you are right about the ECP runway. Apart from bulldozing out of the way all of the concrete flower boxes in the median , a lot of tree-cutting would be required, so I think it would have to be a very serious situation before it was used.
I downloaded the WAC from the CAAS website, so I presume it is relatively up to date (I don't have access to it as I type this). However, Pulau Sudong is not referred to in the AIM, but all the other military fields are. Very strange.
So, here is the next "Which Aerodrome". If this isn't identified wihtin an hour, all regular participants have to miss a turn!
Well, not quite within the hour, but within 10 minutes of logging on.
I thought initially Phuket, but after a bit of searching and head-scratching, I remembered Bali. It's
Ngurah Rai International from overhead Kuta. Open house if correct.