It is believed that the pilot of the Hughes 500 helicopter was spraying an invasive alien plant, known as gorse, for the Department of Conservation around Lake Sumner - a remote high-country lake in the northern Canterbury region - when the accident occurred on Monday.
The NZ Herald reports
that search teams sent out this morning found an oil slick on the lake, in deep water about 150 metres off Breaksea Bay, and believe this to be the site of the crash.
Neither the helicopter, nor the pilot, have been found and land-based, boat and diving search and rescue teams continued to scour the area.
Police received a call from the Department of Conservation at about 2.50 p.m. on Monday to report that the helicopter was overdue.
According to the NZ Herald
The pilot was believed to have been the only person aboard the helicopter when it went missing.
It was one of two helicopters owned by a Rangiora operator that had been spraying gorse and other weeds in the area.
Sighting of debris in the region of the oil spill was reported on Monday. Police stayed at the crash scene overnight and a full ground and water search was launched today.
Police have identified the pilot as 35-year-old Michael Graeme Mehrtens. According to TVNZ
debris including the pilot's helmet and first aid kit were found yesterday.
They also reported that: "Mehrtens, from Rangiora, is an employee of Way To Go Heliservices and is believed to have been the only person onboard the helicopter."