Interestng response,
yarra. Do you really have prescriberd separations in Oz? It may just be semantics but in the UK the books talk about separation between IFR flights and spacing for other requirements - although the only ones that come to mind are wake vortex. I mentioned earlier in this thread that 'general aerodrome control' is not well defined. ICAO Doc 4444 says
7.1.1.1 Aerodrome control towers shall issue information and clearances to aircraft under their control to achieve a safe, orderly and expeditious flow of air traffic on and in the vicinity of an aerodrome with the object of preventing collision(s) between:
a) aircraft flying within the designated area of responsibility of the control tower, including the aerodrome traffic circuits;
b) aircraft operating on the manoeuvring area;
c) aircraft landing and taking off;
d) aircraft and vehicles operating on the manoeuvring area;
e) aircraft on the manoeuvring area and obstructions on that area.
No mention of separation - just keeping it safe, orderly and expeditious. How the controller does that is largely a judgement thing.
To set out minimum requirements for all aircraft/flights seems to take half the fun out of it!
ericliu, in the UK, except in LVOs, the distance from touchdown by which a landing clearance should be issued is usually guidance. In the extreme case, as long as the clearance is issued before the wheels touch down all is OK. Of course, in normal operations landing clearances are issued before that but, again, it's a judgement thing.