The Inquisitor wrote
The methodology of getting to MDA may have 'evolved', but it is STILL a hard floor - unlike a DA, you do NOT go below it unless you have the required visual references. It is not the altitude at which you initiate the MAP.
Actually, in the Airbus if you have the "magic" working properly, and have set the FPA properly at the FAF, and crossed the FAF at the proper altitude, when you reach MDA without the visual reference there should be no hesitation, it's a Go Around. You should have been in a perfect position to "see" the runway, stabilized on the correct approach path to touch down with correct Threshold Crossing Height.
So in that sense MDA
is the altitude at which you initiate a MAP, in a constant descent, if you can't see the runway, ie a Decision Altitude.
Whereas on the DC-9 you got down to MDA, inside the FAF stabilized (but early!) so you could level off, and sit there, peer out, at MDA looking for the runway..