Tarq57: There is already an RNP departure that accounts for single engine climb to the North, developed and in use by ANZ.
It's moot, anyway. The proposed extension is to the South. The road around the perimeter was bridged at the South end some time ago. The water is less deep to the (immediate) South, and there is bedrock. (Well, sort of.) The only disadvantage working it at that end is the Southerly swell in Cook Strait. I imagine there will be a moll or similar protection at the new Southern airfield boundary.
Yep, moot point. Yes there is an RNP departure to the north however I suspect it wouldn't work if the 34 departure threshold was moved further into Evans Bay. It would need designing assuming there could be a suitable new design.
Another moot point is whether or not the protection would ever be needed on the southern end. This proposal doesn't make any sense, the only way they'll pay for is by fleecing the Wellington region rate payers.
How that will go down with the locals is another debate especially since they will be subsidising a private company.
The airlines will also be watching closely to ensure they don't pay extra for something they don't want.
If they start work on the extension it's a fair bet there will be a legal challenge to make the airport comply with the recommended ICAO RESA areas, which they currently don't, or add a EMAS. If that challenge was successful then the cost of the 300 metres extension blows out significantly.
Wellington CC and Wellington airport Co would be smart to drop the whole idea.