Specialist navy and police divers will continue the Lake Wanaka search for missing helicopter pilot Morgan Saxton, who is now presumed dead.
The glacial Lake Wanaka reaches depths of up to 300 metres and specialised sonar and other equipment will be used in the search.
It will continue to centre on the oil slick found off the shore of Mou Waho (or Pigeon Island) about 15km from the Wanaka township.
Saxton and the Robinson R22 helicopter he was flying were reported overdue on Saturday evening on a flight from Haast.
Saxton, 31, is an experienced commercial helicopter pilot based at Haast and was flying to Wanaka to reposition a machine for frost-fighting work.
He was on bail, pending appeal, after he and his father, David, were jailed for more than two years in February, after being found guilty of stealing hundreds of thousands of dollars worth of Ngai Tahu greenstone from south Westland.
Both men are respected rescue pilots, credited with many rescue missions.
Thirteen boats, four helicopters and up to 70 Land SAR (search and rescue) volunteers have been involved in the search since Saturday.
H owever, they will hand over the search to the navy and police dive squads, being flown to Wanaka by RNZAF Hercules and due late this evening. They may start the search tonight, depending on the time they arrive.
Wanaka police station head Sergeant Aaron Nicholson said the three-day surface search by Land SAR Wanaka volunteers had now been scaled down.
"Everything above the water in the search area has now been thoroughly combed," Mr Nicholson said.
"Realistically, we have had to tell the Saxton family there is now essentially little chance of finding Morgan alive. Our sympathies and condolences go out to them."
Searchers have found several items, including a pilot's helmet, flight jacket and gear bag, found floating on the water on Saturday night.
Other items, including a helicopter seat back and first aid kit, were found washed up on the eastern shoreline of the lake.
Mr Nicholson said the Land SAR teams would remain on standby.
"The major effort however is now with the divers," he said.
Searching today was hampered by strong winds and choppy water, and a southerly front is forecast to hit the Wanaka area overnight. The Civil Aviation Authority is investigating the incident.
