A helicopter carrying two people is missing in mountainous terrain in the South Island.
The aircraft was on a training flight from Wanaka to Haast and back with a trainee pilot and instructor on board on Wednesday.
The Rescue Coordination Centre says a search began for the pair at 3pm and is focusing on the Upper Matukituki Valley and the head of the Waipara Valley in Mt Aspiring National Park, west of Lake Wanaka.
The national park straddles the southern end of the Southern Alps. The last known position of the aircraft, owned by Wanaka Helicopters, was near Bonar Glacier.
Two helicopters are looking for the aircraft using night vision equipment, while police are searching on the ground.
The missing aircraft has an emergency locator beacon, but no signal has been detected.
Weather conditions in the area are good and the search will continue overnight on Wednesday.