I was just wondering what is a good seperation distance on approach to landing? I am currently keeping about 9.0nm's to avoid the dreaded "go-around" call - could this be less, or should it be more?
It depends on the aircraft you are flying and the aircraft you are following. If you are on approach speed at around 150 knots or less and so is the aircraft in front, 10 nm should be a good seperation distance. If you are following a smaller aircraft and going faster than them, then a bigger distance might be required, because otherwise you will gain on them and get a go around call.
But, generally, from the point of the aircraft in front touching down, you should be around 8-10 nm behind them. AI traffic is sometimes slow at leaving the runway
Three miles is fine for equal class (medium, let's say). Behind a heavy, leave 4 nm. Behind an A380, leave 11 nm =P