Approach category lesson
Just trying to figure out approach categories. Approach category is determined by Vat which is Vso x 1.3, Vso being stalling speed at max wt in the landing config. Question is, is Vso determined by the manufacturer (eg Airbus) at a standard atmosphere. Therefore is a base approach category determined by the manufacturer. Further is that category possibly changed eg from C to D by the airline ops depending on their own self imposed safety margins. Would the PIC on the day decide to fly a higher category (C to D) depending on weather and weight. In practice is all this hypothetical and what the manufacturer determines is what goes? Several questions there, in particular I'm interested in an A320. Thanks for any explanations. (Confused ATCO)