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Police and Navy divers have found the engine of the helicopter which crashed in Lake Wanaka on Saturday night.
Divers returned to the frigid waters today to sonar scan a "target area" in the search for pilot Morgan Saxton and the helicopter, amid fears they might never be found because of the depth of the lake.
The sonar team can capture images of items underwater to a depth of 100m, but the dive team can only descend to a maximum of 50m.
Sergeant Aaron Nicholson said the helicopter's engine was positively identified at a depth of 74 metres.
The dive team had begun searching the edge of the lake down to 30 metres, he said.
A southerly storm passed through the region overnight, dumping snow almost to lake level, but conditions were forecast to clear today, allowing a more detailed sweep of the crash site, Land Search and Rescue (Land SAR) spokesman Phil Melchior said.
Saxton, 31, and his aircraft disappeared over the lake during a flight from Haast on Saturday evening. Searchers have found no sign of his body.
An oil slick off Mou Waho (or Pigeon Island), about 15km from the Wanaka township narrowed the search for the presumed crash site.
Navy and police divers yesterday searched the area with sonar and specialised equipment and experts began analysing the images last night.
That work would continue today and divers would be sent out to re-examine a "target area" of interest, Mr Melchior said.
Navy diving team commander Lieutenant Commander Andrew McMillan said the lake was "extremely difficult" to search, with steep cliff faces of 45 degrees dropping to depths of up to 300m.
"We can search deeper than we can dive to," Mr McMillan told the Otago Daily Times.
Any attempted recovery mission by commercial divers would take "considerable cost and time", he said.
At the time of the crash, Mr Saxton 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.
- NZPA
