minima vs aircraft category
 

Is there a regulatory explanation behind the different minima applicable to aircraft categories?

Yes, in that most laws in aviation are derived from engineering principles unique to aircraft:

One principle that determines the speed limits for these approach categories is the ability to make the gradual transition from instrument to visual flyng at a given contact height above the terrain:

1. the speed/height combinations are to chosen permit a safe flight path which allows visual correction for lateral and longitudinal deviations associated with the accuracy of the navaid upon which the approach is based.

2. And a height that allows for obstacle clearance and stabilized flight paths to the runway when considering the above correction

edited to add: to also allow a legal missed approach flight path

The detailed [FAA] stuff for diffent types of instrument approaches can be found in TERPS ---TERminal instrument APproach Standards.

For JAA is PANS-OPS (doc 8168), it's available for download on the net, google search. :)

thanks
 

Thank you gentlemen.

You however will find, sailor joe, that many airlines have more restrictive minima than what might be listed on the approach chart, and this is usually specifed in the Operations Specifications (or elsewhere) issued by the regularory authority concerned.
This may well be the case for circling approaches, just as an example.
Some US airlines, for example, limit circling approaches to 1000ft/3 miles (1000ft/4800m) for a category D aircraft, whereas others will be allowed the to use the charted minima, 600ft/2 miles (600/3200m).