why was an approach safe last month but not this month - especially a GPS RNAV which would have zero maintenance costs?
I'm assuming that a certified aerodrome would have someone monitoring obstacles in the approach splays. Possibly the risk with the new rules is that if no one is checking for the obstacles and reports to CASA/Airservices the changes then maybe the approach will be become dangerous overtime. Too large a risk for the regulator and chart issuer.
There would have to be some costs associated with even a GPS RNAV for in flight testing and obstacle monitoring.
Places like EN and AV its hard enough to get an ILS approach in let alone stumbling around on the NDB procedures. It would be good if they could issue training/cloud break procedures for both CWS and WON.