Complete darkness, challenging winds and cloudy skies created the most difficult rescue mission for chief pilot Charlie Beetham since joining the Lowe Corporation Rescue Helicopter crew earlier this year.
Mr Beetham said the chopper responded to a rescue beacon activation on Sunday night. The message from the Rescue Coordination Centre in Wellington was to scramble to a tramper in trouble near Lake Waikaremoana, 63km northwest of Wairoa. The crew prepared for take-off about 10.30pm before "homing in on the beacon" in Te Urewera National Park.
"It was overcast and there were really low light levels. We knew it was for real, we just didn't know exactly what we were going to."
The beacon was triangulated to Sandy Bay Hut on the northern shore of Lake Waikareiti, where 80-year-old Gisborne tramper Michael Willis was suffering from severe dehydration and other medical complications, after walking the Manuoha Track with 14 others.
"I've wanted to walk that track for 15 years and finally had the chance to with the Gisborne Tramping Club," Mr Willis said. "I over-estimated my ability and by the time I got up to the hut [Manuoha hut] at the end of the first day I was struggling.
"Over the next day, walking down to Sandy Bay I got thoroughly dehydrated."
The veteran tramper said there were two nurses in the group who became "quite concerned", and made the decision to evacuated him.
Co-pilot Jeff Taylor and Mr Beetham located the group and navigated their way through the tough terrain and weather using night-vision goggles, which pick up ambient light.
"There is no real depth perception, especially over water with the goggles. They had torches so we were able to pick them up. The problem was always going to be getting him out, the hut was right on the beach front," Mr Beetham said. "It was really difficult, the wind was coming in from the west, which made our approach hard. The helicopter always goes a lot better into the wind, and we were watching our power because it was right at the top of our operating limit.
"We thought about winching him out but it would have been a very high winch job."
The former Royal New Zealand Air Force pilot, with tours to East Timor, the Solomon Islands and a deployment with the Royal New Zealand Navy, said Sunday's landing was one of his "toughest".
"We landed and the rotor blades were over the veranda of the hut and the back of the skids were in the water. There were trees all around the chopper and a perhaps a little bit close to the all-important rotor.
"The skids sunk into the sand, so we were concerned about that as well, but we were on the ground for no more than six minutes."
"It was not an easy place to put a chopper," said Mr Willis. "It was a very narrow beach and if you got it wrong you would have your chopper in the bush."
"He is a very skilful pilot from what I could see. There was just enough beach for me to get on board and it was very dark."
Mr Beecham said it was satisfying to complete a difficult mission that used all his experience and training.
"As pilot, you should never play your last card and always have an escape option.
"Normally if you are flying into the wind you can just pull straight up, so flying with the wind coming from the west I was worried about running out of escape options."
The night-vision goggles enable the crew to take on about 200 per cent more missions than without them.
"They do have limitations, the field of view is only about 40 per cent so you have to move your head around lots, but they have revolutionised night flying."
The goggles are supplied and controlled by the US State Department and the latest models used by the rescue crew were issued in 2007, and cost $11,000.
Mr Willis said he was "damn lucky" the rescue crew got him out. "By the morning I wasn't able to walk. I will just have to do day tramps from now on," he said from his Gisborne home after being discharged from hospital on Tuesday.