In PNG, the usable range of a PAPI or T-VASIS is 4 NM. The requirement is for them to be used by turbojet aircraft. We have a wee confliction in our AIP at present where one section refers to "turbojet aircraft engaged in RPT operations" while, in another part, it simply refers to "turbojet aircraft". I understand that this is being worked on so that the requirement relates to the latter.
Anyway, if the system has failed and there's a Notam on it, there is an automatic 7 days dispensation. Up until very recent times, it was possible for an operator to obtain a further dispensation, for a prolonged system outage, but a recent executive decision stated that no such dispensations will be available. This will mean that turbojet operations to the affected runway will not be authorised.
I don't know if this decision has yet been notifed to the industry, so you might have heard it here first! I feel sure that there will be an objection or two and there could be an awful lot of brown stuff impacting fans in PNG, in the very near future.
If the system fails during the landing approach, it is the subject of an Air Safety Incident Report. The pilot will observe company SOP in deciding whether or not to continue and land but, whether the aircraft lands or not, the ASIR is required.