Roy Arbon is overdue from a walk on Wednesday up Mt Davy to Mt Sewell, north-east of Greymouth.
Police said today they have concerns for the 75-year-old, due to harsh weather conditions.
They said Arbon may be wearing a blue puffer jacket, shorts and hiking boots - but this is not confirmed.
A search is under way in what police described as mountainous and challenging conditions.
Those involved included police Search and Rescue teams, LANDSAR volunteers from Greymouth and surrounding areas, and a Search and Rescue dog.
Teams were on the ground canvassing areas and tracks Arbon may have taken. Helicopters were also being used, police said.
"Although the 75-year-old is believed to be an experienced hiker, there are concerns for his well-being, given the length of time he has been overdue with no contact and the cold temperatures."
Police are appealing for any sightings of Arbon or information about his movements from Wednesday.
People can call police on 105, quoting job number P063265345.
Antarctic work after Erebus crash
Arbon was working for the Antarctic division of the Department of Scientific and Industrial Research in 1979 when Air New Zealand Flight 901 crashed into Mt Erebus on Ross Island on November 28.
He later detailed his involvement in the recovery effort to NZ History.
"Conditions were dangerous. We were working on a glacier, and we did not know where the crevasses were. When these were found they were marked with a flag. I remember carrying a suitcase with all the paraphernalia in it with an ice axe in the other hand probing for crevasses.
"One thing that has stayed with me is the smell of unburnt aviation fuel. When the plane went down there was a blast from the aviation fuel but not all of it burnt off," he said.
"When I returned to Scott Base after the recovery phase, I was asked to help erect a memorial cross on the site. This was done in a gale-force wind so bad the helicopter could not shut down. I believe this was because the wind was blowing so hard, they wouldn't be able to get the machine started without damage to the main rotors."
Arbon also helped to recover the bodies of 14 people who died when a viewing platform collapsed at Cave Creek in Paparoa National Park in 1995.
Arbon later fell prey to international drug smugglers. He was detained in Australia after a suitcase he carried from Brazil was found to be concealing more than 2kg of cocaine.
He was found not guilty of drug smuggling following a trial at Western Australia's District Court.
The story was later told in the documentary film The Scam.
