Originally Posted by
aviationluver
I remember reading about the Microwave Landing System (MLS) years ago in aviation textbooks in the states. Supposedly, (back then), the MLS was going to be all the rage and replace most ILSs. What happened? I don't know of any MLS approaches? Was it a funding issue as to why the MLS never went forward or did the GPS do in the MLS?
From a response on PPRuNe to a similar question re MLS in the UK :
MLS is not supplanting ILS, in fact MLS will be dead and buried within a few years. It's not that funding is going to run out, it's that nobody manufactures the system any more, and the current one is about to reach it's end of life. The main benefits of MLS (smaller sensitive area in CAT II/III ops) have largely been replicated by the new 32-element array ILS localiser antenna on the market now anyway.
A standard RNAV GNSS (APV Baro VNAV) approach can't get to the same decision height as a CAT I ILS, so that won't do it either.
GBAS will, especially when CAT III certification is granted.
However, even new aircraft coming out of the factories now are noit fitted for GBAS, so ILS will be around for another 30 years at least.