Missed Approach Altitude Setting
Airbond, in reply to your post,
The missed approach alt is set on the MCP after passing the FAF.
The Non Precision Approach is flown as a continuous descent to replicate as closely as possible an ILS. The idea being that the MDA effectively becomes a DA. i.e at MDA if nothing is seen then a G/A is flown from this point.
This is the way my last two companies have taught it and, if you think about it, it makes sense.
Unlike a light twin, if in, say a 737 or bigger a/c you actually flew level at the MDA, it's highly unlikely that you would be in a safe position from which to land if you did become visual. Not to mention the possibility of level flight just a few hundred feet above the surrounding terrain (think Zurich etc...)
Flying the continuous approach means that if you sight the runway by MDA you can continue a stabilised approach to land in as normal a manner as possible.
Hope that answers your query.