Hi 172,
PAPI: Precision Approach Path Indicator
NPA: Non-Precision Approach.
PAPI's may not always be set to the same angle as the NPA in use and dependent on your a/c type, may also not be set for your eyeline.
So, as part of the brief, you need to check a) the PAPI slope and b) if / where the lateral track of the NPA intercepts the RCL.
With the exception of a no-go-below altitude, the tolerance is +/- 100' for a NPA vertical profile. Assuming you have maintained this correctly down the approach and you are stable at your relevant SOP'd gate, then you MAY NOT BE INTERCEPTING THE PAPI's. A NPA, by definition, is not as precise as an ILS or approach flown on PAPI's / VASI's.
Once visual, especially with a transition close to minima, dont rush the decision; let your mental model adjust. Check the ROD is sensible (usually c.700fpm for 3 degrees GS dependant), how did the final altitude check against actual a/c alt? If all is good, gently adjust onto the PAPI's (if they are there). At 200' you will have an idea if the approach is going to work or not. 4 whites at 200' is a good clue to GA!
DA is not a decision to land (hence your SOP wording), it is a decision to CONTINUE THE APPROACH assuming stable criteria are still being met. Your stable criteria from your ops manual appear not to be too helpful with regard to NPA's. I would assume +/- 1 dot as +/- 100' in this case.
Hope that helps. If you have any questions PM me.