The search for the pilot of a missing helicopter has been suspended for the night, several hours after chopper wreckage was spotted on an island in Lake Wanaka.
The search started shortly before 1.30pm on Saturday when the rescue centre was alerted to a Robinson helicopter carrying one person which had disappeared from its tracking system.
Three helicopters from the same company retraced the flight path of the missing chopper and spotted a wreckage on the shoreline of nearby Stevenson Island, as well as an oil slick in the water 1km north.
Rescue Coordination Centre NZ senior search and rescue officer Chris Henshaw said it was confirmed the wreckage was that of an R44 Robinson helicopter.
Maritime rescue co-ordination centre, police and Coastguard are all involved in the search, but the mission has had to be suspended until the morning.
"Another team will land on Stevenson Island where wreckage was seen to establish if further information can be gleaned," Henshaw said on Saturday.
He said there was one person aboard the helicopter when it went missing.
Six helicopters have been involved in the search, including the three choppers from the company of the missing craft.
A police spokeswoman said it received reports of a downed helicopter, but Maritime New Zealand's Rescue Co-ordination Centre was leading the operation.
Metservice meteorologist Ravi Kandula said it had been a "cloudy, gloomy day with reduced visibility" since about midday in Wanaka.
There had been occasional steady rain and cloud had dropped to about 1000-1200 feet.
While there had been some gusts late morning, the wind had not been "spectacular" for most of the day.
The Transport Accident Investigation Commission (TAIC) has opened an inquiry into the suspected crash.
The chief investigator of accidents, Captain Tim Burfoot, said the commission appointed a team of two investigators, who are due to arrive at the accident site tomorrow.
The commission opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow the commission to make findings or recommendations to improve transport safety.
TAIC put Robinson helicopters on its watch list - the highest alert it can give - in 2016.
Citing 14 mast-bumping accidents costing 18 lives since 1991, the commission called for renewed testing of Robinson helicopters, among other recommendations aimed at promoting safe handling of the machines.
The Department of Conservation suspended use of Robinson helicopters in November 2016 because of safety concerns and has now made the move permanent following external and internal reports.
The estimated additional annual cost of using helicopters other than Robinsons is $350,000.
Robinson helicopters make up 35 per cent of the New Zealand fleet but 49 per cent of accidents, 64 per cent of fatal crashes and all seven fatal mast-bump accidents.
Lake Wanaka is New Zealand's fourth largest lake, at 192sqm and an estimated 300m deep.
The lake is used for adventure tourism all year round.