It's not only turn radii that determine approach category, but also distance covered on time-based straight lines (that is, where outbound distance is timed rather than DME based). You are supposed to fly the entire approach at the correct speed to ensure that you don't get too far from the start point before the turn.
ICAO has tried hard to develop standards and recommended procedures that work everywhere in the world, from Canadian winters to Afghan summers. The rules might seem a little silly around benign terrain and well designed airfields in SE England.
What you suggest would probably work just fine in Britain, but how could you safely remember to apply this set of procedures in EGBH and that set of procedures in say Tibet? The men in white coats at ICAO seem to think it's best to have one set that work everywhere.
Cheers,
O8
Last edited by Oktas8; 12th Mar 2007 at 07:15.