Mr Beck has not been seen since he left his tent at Bevan Col on the mountain on Sunday morning to check a route to the Matukituki Valley.
Land Search and Rescue Wanaka members and police believe Mr Beck has had a significant fall, possibly into a crevasse or down a bluff.
Mr Beck's family were expected to arrive in Wanaka from Melbourne yesterday afternoon to be briefed by search coordinators.
Sgt Nicholson said yesterday that despite the negative scenario it was important to remain positive and not give up on Mr Beck.
‘‘We are giving him the best chance . . . we are treating him as one of our own,'' he said.
Searchers would be back on the mountain as soon as the weather improved. They had to stay off it yesterday because of strong winds but hope to resume this afternoon or tomorrow.
It has emerged Mr Beck was on Bevan Col several years ago.
Christchurch climber Cameron Mulvey (32) said yesterday he found Mr Beck to be a safe and experienced climber and the kind of person who easily found humour in uncomfortable situations.
Mr Beck had shared his two-man tent with Melbourne climbing companion Andy Parker, Mr Mulvey and Finnish climber Anna Ruotsi (27) on Friday and Saturday night.
The four had been having a good time and were not in any danger, despite their claustrophobic circumstances, Mr Mulvey said.
‘‘It was really uncomfortable. We didn't sleep great but we still managed to have a laugh and have a great time.''
Mr Mulvey, an experienced climber who works as a field technician and looks after a Canterbury University tramping hut at Mt Cook, said he had no qualms about Mr Beck leaving the tent on Sunday to check the area.
‘‘Anyone of us could have gone and done it. He was just scoping out the route . . . sure, if someone doesn't have the experience Alan has, they wouldn't go out of the tent and have a look. It seems just the visibility has cost him. Anything can happen,'' Mr Mulvey said.
Mr Mulvey and Ms Ruotsi met Mr Beck and Mr Parker at Colin Todd Hut on Monday night and quickly struck up a friendship.
The four climbers left the hut on Thursday to climb together to the summit. Poor visibility slowed their progress and they turned back to Colin Todd Hut.
On Friday morning, Mr Mulvey radioed his intention to leave the mountain via the route to the Matukituki Valley to a friend, Wanaka climber Paul Rogers. He gave Saturday as the ‘‘panic date''.
Mr Beck and Mr Parker had intended to stay at the hut until Sunday, but also decided to walk out, he said.
The four climbers made their way across the Bonar Glacier but the weather deteriorated again, forcing them to camp on Bevan Col in Mr Beck's tent.
That night there was a storm with heavy rain and strong winds and bad weather continued until Sunday morning, when it began to clear and Mr Beck left the tent.
Mr Mulvey and Mr Parker started searching when Mr Beck did not return, while Mr Rogers and Wanaka police began looking for Mr Mulvey and Ms Ruotsi.
‘‘They had no idea he [Mr Beck] was missing. It was a strange scenario. They were looking for us and Alan happened to disappear off the face of the Earth that morning,'' Mr Mulvey said.
Mr Mulvey said he was pleased the search team arrived on Sunday afternoon when it did. He hoped to go back into Bevan Col to show searchers where he saw Mr Beck's tracks.
Constable Mike Johnston said an alpine cliff rescue team, to be led by Wanaka mountaineer Brian Weedon, would check crevasses and gaps in the Bonar Glacier when conditions permitted.
The search would become very technical, with mountaineers lowered on ropes into holes and slots, creating ‘‘all sorts of risk factors''.
Mt Aspiring was not a pleasant place to be yesterday and two more fronts were due to come through, Const Johnston said.
