likewise the departing needs to be beyond a certain point (still on ground) before lander crosses fence.
Rather poorly interpreted and written in the AIP Supplement by CAD, however the ICAO PANS-ATM requirement is that the departure
is airborne at the time when the arrival crosses the threshold.
Throw a dyce, you'll no doubt be relieved to hear that CAD couldn't help themselves but add another 500m to the ICAO standard on 07R/25L - coz this is Hong Kong. You remember.
.....landing clearance may be issued to an arriving aircraft provided that there is reasonable assurance
that the following separation distances will exist when the landing aircraft
crosses the runway threshold:
(a) RWY 07R/25L
(i) Landing following departure –
The departing aircraft is/will be airborne and has passed a point at
least
2 900 m from the threshold of the runway (abeam TWY K4
for RWY 07R or TWY K2 for RWY 25L).
There is no need for the extra "/will be" in the separation standard. The condition that must exist is that the aircraft is airborne. The application of the standard allows the controller to forecast that that condition will exist.