[rlpb]

> It's not uncommon for a tower controller to allow a plane to takeoff while another is approaching the runway.

Only in the US is it permitted for the controller to clear an aircraft to land while another is using the runway. The rest of of the world does not allow "anticipated clearance".

(Apart from a "land after" clearance where the landing aircraft must accept responsibility for separation.)

Edited to add: how it works everywhere else in the world: the controller is not permitted to clear an aircraft to land unless and until the previous one is confirmed clear. That's why the term is "cleared".