Does it only depends on the speed as the main restriction? If you are landing for some reason at high speed even in Cessna cat A you have to use appropriate higher category.
As the turning radius depends on the speed so the aircraft category. A bigger turning radius requires greater obstacle clearance. As far as I remember 737 can be C or D depending on the VREF.
That pdf says:
Aircraft Approach Category - A grouping of aircraft based on the indicated airspeed at threshold, as follows (source: PANS-OPS Doc 8168 Volume I, ICAO):
If you landing flap less on A320 you probably have to use D.
Last edited by Turbavykas; 17th Jan 2013 at 13:13.