Think it was the military who flew curved approaches from downwind curving right onto final!
The idea of any approach and a circuit is an approach is to get you onto the runway to land not 1 mile out 2 miles out 3 miles out etc. Theoretically it could be just before you touchdown!
Wherever you hit the centreline is the point that coincides with the correct altitude for roughly a 3 degree glide.
6 miles 2000 feet 3 miles 1000 feet 1.5 miles 500 feet etc is a rough guide that is easy to remember and calculate.
In many ways it is probably better to visually extend the centreline and pick a prominent spot on the centre line like a farm or whatever and use that as a visual final approach fix. That is what you will fly over at a given altitude depending on an estimated distance from the runway.
Be 90 degrees to that point and passing 90 degrees start a curving approach.
may not be an official way but it works
Pace
Last edited by Pace; 10th October 2012 at 00:20.