Interesting, in the both the replies so far it is accepted that you must protect the MDA/H associated with the NPA flown as a non-CDFA. Where is this stated?
When flying CDFA you are flying to a DA as per the annex 1 definitions:
(83) ‘non-precision approach (NPA) operation’ means an instrument approach with a minimum descent height (MDH), or DH when flying a CDFA technique, not lower than 250 ft and an RVR/CMV of not less than 750 m for aeroplanes and 600 m for helicopters;
By my interpretation of AMC3 CAT.OP.MPA.110 the minimum available DA/H for a CDFA approach may be limited by the same OCH as that which determines the minimum available MDA/H for non-CDFA i.e. the two figures could be the same. However, when used as a DA you would only be required to initiate the GA at that altitude and some transient dip beneath would be permissible.
Admittedly, in the vast majority of cases the extra 20-50ft will not be the deciding factor on whether you get visual references or not so it becomes academic, it’s more a question of what should be taught from a standardisation perspective, and what is actually compliant.
I’m happy to be proven otherwise but I think adding a margin to the MDA when deriving a DA for CDFA operations may be a fixed wing carry over as that is where CDFA has come from, and they are required to add on a margin under AMC1 CAT.OP.MPA.115. I can’t see anything which prohibits you from dipping beneath the OCH as part of the go around manoeuvre when flying CDFA to a DA. I’m happy to be corrected if someone can point me to something which states otherwise.
Last edited by Aucky; 26th Apr 2020 at 22:54.