Twenty-eight potential sites for a new airport have been identified in Whangarei.
Whangarei's Onerahi Airport has 10 to 15 years of life left in it, but its runway cannot be extended in length or expanded.
Under Stage 2 of an Airport Locations Options Study, Beca consultants have earmarked 28 potential sites, to be whittled down to two or three.
The consultants are looking for about 50 hectares of land with no surrounding hills.
Their $260,330 study contract has been allocated a further $120,000 by the Whangarei District Council because of the high number of potential sites.
Simon Weston, the council's group manager infrastructure and services, said Whangarei was fortunate to have so many potential sites.
"Some are better than others and some have got very good attributes," he said.
"I had a horrible feeling that we would struggle to find sites."
The sites are not being publicly identified yet, until they go through an assessment process. It was early days in the 10-year project.
He said the district council was looking for a "big piece of flat land with no hills on either end".
The Stage 1 - Whangarei Airport Strategic Review - looked at the existing airport and the constraints of the aerodrome, as well as future requirements.
Port Nikau had been earmarked as a potential site but it was "not as feasible as hoped" because of the surrounding terrain.
The cost of establishing a Port Nikau airfield was about $148 million - significantly more than the estimated airport cost of $25m to $40m - because of a need for harbour reclamation.
If other sites had similar issues, and there were no practicable options, Port Nikau would still be evaluated against those.
Stage 3 would involve an in-depth investigation into the top ranking sites, with Stage 4 moving to consent/designation/procurement of land and a recommendation when to commence the enabling works.
The existing airport was coping well amid a booming tourist industry and could serve the city for another 10 to 15 years, Mr Weston said.
A million dollar makeover has seen work including self check-in kiosks, an improved baggage claim area, a children's play area and the terminal size doubled, along with a new taxiway, new toilets and an extra 20 carparks.
That upgrade was funded by $210,000 from the district council, $210,000 from the Crown and $600,000 from the council's Airport Reserve Fund.