Thank you all for your replies.
It certainly varies from airport to airport, operators to operator and based on several factors (wx, a/c categories involved, etc). I understand that everyone is quite happy with it and it has been working without significant issues. Being a "safety" guy, I am looking on how we can improve such a lack in the rules or at least have a little more guidance.
What ICAO says is that the landing clearance is based on "reasonable assurance" that the runway is clear when an arriving aircraft crosses the threshold. It says also that if under radar control, the landing clearance shall be issued not later than 2 miles. Makes sense to me as the minimum separation would be 2.5NM (based in certain conditions - RWY occupancy time, Xwind, etc).
Just a big headache trying to do a torough analysis of this particular occurrence. Your inputs are helping.
Thank you.
