KEY POINTS:
It is a strange day here in Geraldine, where the sky pushes flat against the land. Here, 82 volunteers are spending their weekend searching for something that may not be there at all.
They're looking for the wreck of a plane that dropped off radar almost 10 years ago but aren't expecting much. Even an empty plastic box would be a mystery solved: 23-year-old Ryan Moynihan had two cartons of whitebait containers in his Cessna 180 when he left Haast on November 8, 1997.
Officially this is a search and rescue training exercise.
But Darryl Sherwin, the man whose mathematical formula found the crashed helicopter of liquor baron Michael Erceg, says he is 95 per cent sure Moynihan's plane is in a particular basin of bush on the eastern slopes of Mt Peel. A big red cross marks the spot and an Air Force Iroquois is ready at the Peel Forest base, waiting to ferry search parties in.
Michael Moynihan, Ryan's father, stands politely to one side as CAA accident investigator Tom McCready gives the group the basics.
There are two ways to crash a plane, McCready says.
"It can make a line through the trees.
"If you can imagine coming down through the trees, the wings peel off pretty quickly. The fuselage would be like a dart. The tail end, of course, tends to stick up... Or else, if it's decided to spin in, it'll just impact the ground and the wreckage will be in the area of that tent."
Although the basin is a hotspot, searchers tramp to the top of the mountain and work their way down in a line, methodically. It will take most of the day to work down to the X. They'll fly out at dark and start again in the morning.
The helicopter drops the searchers directly opposite the basin, on a spur of golden grass thick with flies.
A group of young policemen from Christchurch gulp cans of creaming soda and confide they'd rather be at the cricket.
The older guys, the search and rescue gurus, smear on the sunscreen and inspect the bush with binoculars.
It's a nasty little creek, they say, nodding across the gully at the steep, dark bush fingering up dry rock faces.
Sherwin sees this spot differently.
After months of late nights and maths, he's as sure as he can be that the plane is in there. "Don't you write that," he grins. "Just say that I'm 'confident'."
His is a confidence to have faith in: this is the man whose calculations put him within 500m of the patch of bush that hid Erceg's crashed helicopter.
Erceg crashed into such a dense patch of bush, that helicopters flew over it countless times before spotting a single skid sticking out. One more second in the air and the wreck would have been in open farmland.
Sherwin's kicking himself now that he didn't persevere with an equation that could have leapfrogged the multimillion-dollar search.
He deals with "absolute facts".
And this weekend he is wired, pacing the campground, hoping, hoping, and trying not to promise.
Mike Moynihan first heard from Darryl 12 months ago, when he called to ask whether he could look into his son's disappearance.
Through all of the talk of wings peeling and planes impacting, Mike is calm. He slept "perfectly" last night, used to the to-and fro of hope; humbled, but not excited, by the scale of the search.
"It is a funny old day. It's really nothing to be excited about. If it was going to bring Ryan back, it would be exciting."
In the urgent, desperate weeks after Ryan disappeared, the helicopters flew every day.
Mike spent a fortnight leaning out of windows staring at the ground, clattering between Haast and Lake Tekapo, West Melton and the other side of Mt Peel.
How does a parent stop searching for his son?
"We ran out of places to look. You just can't take [friends and neighbours] away from their families and their work."
Every day he wonders. "I think it's a male thing. The male wants to know what went wrong. [Ryan's mother] just wanted him back."
Mike goes quiet when the Iroquois thunders in to pick up the first searchers. "This is going to be huge, isn't it?"
