Anna Mowbray-Ali Williams helipad proposal: Report to look at effects of noise and downwash on swimmers and birds at Coxs Bay

Ali Williams and Anna Mowbray before demolition. Photo / Instagram

What effects will helicopters landing and taking off from a Westmere waterfront home have on swimmers, sailors, roosting birds, kite surfers, paddleboarders, walkers and rowers at Coxs Bay?

That's the central question addressed by planning and resource consent specialist Mark Benjamin of Mt Hobson Group, and others in new documents submitted to Auckland Council.

The council sought more information on the effects of a helipad, proposed by ex-All Black Ali Williams and businesswoman Anna Mowbray of the global Zuru business.

Coxs Bay, Westmere. Photo / Alex Burton

The couple demolished a home on their site overlooking the bay and are building a larger three-level residence for their family. They also want helicopter facilities at the site.

They have said they don't want to comment to the media on their application.

Some neighbours have expressed concern about the application.

Helicopter pilot and specialist aviation industry adviser John Fogden told the council about "rotor downwash", which happens when a helicopter hovers close to land or water and which could affect kite surfers, sailors or other water users if they are below the flight path.

The applicant site. Photo / Brett Phibbs

The wash would affect people within about 60 metres of the helicopter.

"Such effects would be negated by the actions of the pilot complying with Civil Aviation Rules," Fogden's submission said.

Mt Hobson told the council the helicopters' effects on swimmers would be limited.

"Due to ongoing water quality issues within Coxs Bay - monitoring indicates a high risk of illness from swimming - there are only very rarely people swimming."

Kitesurfers don't enter the sheltered Coxs Bay "due to moored boats and lack of wind", Mt Hobson said, and are usually only seen on windy weekends.

The area was only accessible for kayakers, paddleboards and rowers within around one and a half hours of high tide. Outside these times, the water receded from around the headland, Mt Hobson said.

Ali Williams and Anna Mowbray before demolition. Photo / Instagram

Mt Hobson said walkers and dogs sometimes used the area around the headland but only up to three hours before or after high tide. There was no walking around the headline during high tide, the report said.

The council was concerned about how a significant variable and pied oystercatcher roosting place at the base of a cliff north of the proposed helipad would be affected.

Mt Hobson said the effects of flights from the property on the roost were assessed as high but spasmodic - only when the flights coincided with high tide and when the roost was being used by the birds.

Coxs Bay, where the effects of helicopters on birds were studied. Photo / Michael Craig

A written submission from Treffery Barnett, a biologist of Bioresearches, said although the point appeared to be a well-used high-tide roost, more than 20 structures less than 2km to the east would provide safe roosting areas.

Reports by Hegley Acoustic Consultants and Heletranz general manager Gemma Parton assessed noise levels.

"We have reviewed the proposed helipad location and consider that it is suitable for use by the proposed aircraft," Parton said.

If a pilot determined the site to be unsuitable or compromised for landing, they would use their skills to determine the safest course of action, she said.

That would include options outlined by pilot Fogden in his report, Parton noted.

A council spokesperson said the application was still on hold, no decision was made and the planner was now assessing the new information.