A Cat C aeroplane can legally do 160 down final. It seems that you need to change your RNP design parameters to cope with that.
If you do not understand how the coding works, why do you bother to reply?
The explanations in the posts details how it works, it also shows why there are known issues with RNP traffic vs non-RNP traffic. There are plenty of stories and dialog about the RNP ac being too slow on final. That is one of the reasons.
The issue is not if it is legal or not to exceed 140kts on final for CAT C, it is simply that the coding will not accept that. There is a speed per leg, that is just the way the FMS understands it.
The FMS is horribly outdated as far as the programming goes, and with the way certification of systems goes, it it not likely to get better very soon.
Skyjob...the CAT is based on MLW and flaps 30, you can search that criteria online if you want, and I did provide a table. There is always a set standard that the criteria is based on.
Looking at the table, you have to look pretty far down the weight table to get below 140 kts, and in reality, you see very, very few 738's going over the threshold at 140kts...
Just so you are aware, there are other requirements such as runway length that are also based on flaps 30.
I understand that quite a few carriers SOP is flaps 30, that came about when fuel costs were so high, and flaps 30 was to save fuel.