hrmm.. i'm not an approach/departure guy, but i've been involved in approach simulator execises and approach layout setup.. i try by best to answer..
1. like KLIA, approach airspace is from 2500ft to FLV140, consist of two airspace structure, TMA (terminal control area) & CTR (Control Zone). minimum seperation is 3Nm, but most of the guys will do 5Nm. this because they have to cater bout weather, departure from KLIA, Subang & Simpang.. 1000ft apart with no closing speed. when establish on a ILS, acft is cleared for approach on a same level, about 20Nm from TDZ.
2. For outer control zones, it depend on location bro... just name the location, maybe i can specify it.. like bukit jelutong area, it's not a approach path, but when B737 holding, it sure hit the area less than what the onboard alltitude indicator show.. unless they have radio altitude indicator.
