Whilst it is tempting to slot in ahead if safe to do so and the other aircraft is not on final, it may turn final from far out whilst you are flying a tight base leg, so, it maybe worth bearing in mind the following legal considerations.
Rule 17(5) on collision avoidance requires you (absent contrary instructions from ATC) to "conform to the pattern of traffic formed by other aircraft intending to land at that aerodrome, or keep clear of the airspace in which the pattern is formed". This suggests that the circuit (or pattern) is made by the aircraft flying in it at any given time (whatever the standard pattern or local circuit diagram may indicate), and so you must follow the aircraft ahead. Note also, however, rule 17(6), which states that "An aircraft while landing or on final approach to land shall have the right-of-way over other aircraft in flight or on the ground or water. It goes on to say that "in the case of two or more flying machines, gliders or airships approaching any place for the purpose of landing, the aircraft at the lower altitude shall have the right-of-way, but it shall not cut in front of another aircraft which is on final approach to land or overtake that aircraft." ATC can give instructions for landing priority.
This suggests that you may overtake in the circuit (but never on final). ATC instructions obviously do not apply in your scenario as the airfield only has FIS, and the numbering passed by the FISO is for information only.
Probably best to stay behind, even if this requires a go-around, or orbiting (if safe to do so: I'm personally not very keen on orbiting within circuits unless told to do so by full ATC). Or, as suggested above, slow down (lower flaps etc). A few more notches on the hobbs meter don't matter terribly, after all.
PS: also probably better, if uncertain of the other aircraft's intentions, to stay where you can see it, at least until it has landed or gone away.
Last edited by FNG; 30th March 2004 at 07:51.