FMC setup for a circling approach

It is speed driven. Normally you will circle at flaps 15 at flaps 15 maneuvering speed. If that speed puts you at CAT C, use it if you want. The BBJ guys in my company use either C or D based on the speed. You can also be conservative and use CAT D. Just keep in mind that this could limit you if the weather is below CAT D but above CAT C.

Thank you sir.

Bert Van Bulck