non-precision Instrument approach:
MDA = minimum descent altitude
MDH = minimum descent height
MAPt = missed approach point
green line: runway in sight → continue descent below MDA/H
red line: runway not in sight
before reaching MAPt → hold altitude
when reaching MAPt → missed approach/go around
Own work, incorporating C 172 line drawing.svg
C 172 line drawing.svg: Werneuchen
everything else: El Grafo (talk)