A monitered approach is a fantastic tool for low vis conditions where the approach is flown normally by the F/O in Cat 3's and autolands or by either the Capt or the F/O in a Cat 2.
The whole idea is that the whole approach and a go arround is the focus of the pilot flying(PF), and the PNF "moniters" his action to decision height where the PNF is looking for the required visual reference to land, a instant call of Land or Go arround can therefore be made by PF when PNF calls decide,and controls are instantly handed over if landing. Hence why the capt is normally PNF.
Im sure this is how most commercial aircraft fly low vis approaches, whether they call it a monitered approach or not !!!
