Overlay approaches were discarded here in favour of a runway approach with a profile.
The overlay is used in the USA for VOR [and NDB where/if they exist] with minimal cost to the user as it's simply another use for the same [previously surveyed] chart.
The Oz concept was designed to be safer with lower minma.......now, let the debate on the distance measurement vs spacial orientation begin!!
G'day
PS you're mad if you don't have the gps backing up the ndb, and of course, quite usable as a DME substitute where specified!
