A rescue pilot says a plane crash which happened in the Southern Alps yesterday is an "unsustainable crash to live from".

A light plane with a sole occupant was located near Mount Nicholson yesterday after failing to arrive at its destination.

The pilot was travelling from Franz Josef to Rangiora, and there were strong winds forecast.

Westpac Rescue Helicopter pilot Stuart Farquhar wasn't on duty yesterday, but has spoken to the crew who located the plane.

"It was pretty much in one place, but it was like it was crushed, really," he said.

"There was nobody to get from the scene that was likely to be alive."

He said it was difficult for the crew to get to the crash site, with high winds, turbulence, low cloud, windblown snow and flat light.

But conditions were clearer at the crash site, and the crew was able to hover above it.

"They took photographs and videos of it and got as much information as they could," he said.

RNZ understands the pilot is Tim Gibb, a long-term Franz Josef resident and business owner.

The air force has now been called in to lead the operation, but crews won't be able to access the site until tomorrow at the earliest, due to continuing strong winds.