Still out of range of Butterworth and unable to establish a track. Any RSAF AEW wanting to peak at the bases in the north would have to stay out over the straits or South China Sea and be vulnerable to being cut off from Singapore by a fighter launched from southern Malaya.I dont think that its going make that much of a difference. For starters the Sing G550 and E2 would likely have a detection range somewhere in the region of 200NM or thereabouts. Sit them up above Singapore or slightly forward ready to retrograde if required.
There is enough leeway for Butterworth based aircraft to dogleg around the field of regard of Singapore local AEW to come in from all points. Even up from the Java Sea with IFR over Borneo. So they are going to have to split their efforts to intercept all these incoming packages, most of which can of course be decoys and turn around after the RSAF interceptors are far enough away from the real action.
Sure but launch warning isn't as big a deal as tracking the packages. You've got to assume everyone will have launch warning. Even for isolated bases commercial imagery sats can provide it. But ground based radar on the Malaya peninsula can track fighters taking off from Singapore even if they stay real low. The only way they can get any room from being watched is to go out into the south China Sea where we will probably have naval assets anyway. Also its much easier for a RAAF/RMAF AEW to stay close enough to Singapore to watch everything. They just do so orbiting over KL.Secondly this would likely be supplemented with visual observers either in butterworth or more likely just sitting on Penang Island. Its not like you can hide a strike package taking off from Butterworth.