Dear Stator Vane,
To satrt the full answer to this query, here is an excerpt from ICAO Annex 2 - Rules of the Air
...3.2.2.3 Converging. When two aircraft are converging at approximately the same level, the aircraft that has the other on its right shall give way, except as follows:
a) power-driven heavier-than-air aircraft shall give way to airships, gliders and balloons;
b) airships shall give way to gliders and balloons;
c) gliders shall give way to balloons;
d) power-driven aircraft shall give way to aircraft which are seen to be towing other aircraft or objects.
...3.2.2.5 Landing
3.2.2.5.2 When two or more heavier-than-air aircraft are approaching an aerodrome for the purpose of landing, aircraft at the higher level shall give way to aircraft at the lower level, ... Nevertheless, power-driven heavier-than-air aicraft shall give way to gliders.