So what is the financial and safety cost?
There is no safety cost. There may be a safety benefit. But when the aircraft are getting vertical guidance via RNP, what is the extra safety benefit that an ILS will deliver? There is also an implication that the current procedures are unsafe, I do not agree with this. They may be less efficient.
Financial, I can't argue with that. But you would have to answer the questions below to compare apples with apples.
How many flights have carried significantly more fuel than they should have to out last significant weather conditions?
How many flights have carried out more than one non precision approach to become visual some at night with the tower closed.
How many flights have been cancelled due to the weather forecast/actual conditions not being suitable for a non precision approach.
How many flights have had to use Brisbane alternates further up or down the coast because OOL lacks a precision approach aid?
Can you answer these questions?
Someone 'close on the project' should talk to some pilots, some flight planning officers and some Airline executives to see if those "two repeat two" diversions stack up against the safe, efficient, and financially viable expectations that we all have for OOL.
Why do you assume I haven't? Ad-astra I like the idea of an ILS. So do you it appears. You clearly seem to think that an ILS is essential for Safety and Efficiency at Gold Coast and on face value you are probably right. Currently, the airlines don't support that view. They would rather we develop RNP.