The basic rule is as follows: “A flight crew member must, during a flight, maintain vigilance, so far as weather conditions permit, to see and avoid other aircraft.” The regulations construct a table of scenarios that must be followed in the given circumstances.
When two aircraft are on converging headings at approximately the same height, the aircraft that has the other on its right must give way, except, an aircraft mentioned in the following list must give way to an aircraft listed above it in the list:
- a balloon;
- a person descending by parachute;
- an unpowered glider;
- an airship;
- an aircraft that is towing something (including another aircraft);
- a power‑driven aircraft.
For example, if a balloon is converging with a power-driven aircraft, then the balloon has right of way.
When two aircraft are approaching head-on and there is danger of collision, both aircraft shall alter its heading to the right.
When two heavier‑than‑air aircraft are conducting an approach to land at an aerodrome, the higher aircraft must give way to the lower aircraft.
However, if the higher aircraft is in the final stages of an approach to land, the lower aircraft must not take advantage of the higher aircraft’s need to comply with the above regulation to cut in front of the higher aircraft. Note that a power‑driven heavier‑than‑air aircraft must give way to an unpowered glider.
Any other aircraft must give way to the aircraft that is compelled to land, i.e., during an emergency (such as an engine failure).
Any other aircraft (whether in flight or operating on the ground or water) must give way to the aircraft that is landing.