CASA has published a new draft Civil Aviation Advisory Publication (CAAP) on non-precision approaches. CAAP 178-1(2) is available on the CASA website now.
The CAAP provides guidance on how to conduct NPAs safely and brings together all the requirements, standards and practices into one document.
The term "NPA" covers several type of approach including NDB, VOR, LOC and RNAV. It does not cover ILS, which in Australia, is the only type of precision approach.
An NPAs takes a pilot down to a safe point on instruments, from where the rest of the approach and landing is done visually. That point can be one of three things:
NPAs can be associated with only registered or certified airports. The reason CASA gives is that potential obstacles can't be monitored if the airport is not certified or registered.
The draft CAAP can be read on the CASA website here.