When four young men set off in summery conditions to climb the Otira Face of Mt Rolleston, no thought could have crossed their minds that winter would slam into them like a freight train, leading to one of New Zealand's worst alpine tragedies.
All four - and a member of the more-than-100-strong search and rescue team - died on the 2275m mountain in the Southern Alps near Arthurs Pass on the border of Canterbury and Westland in June 1966.
The five are to be remembered at a memorial service in Arthurs Pass today.
Kiwis Bruce Ferguson, 19, of Christchurch, and Colin Robertson, 20, of Invercargill, joined Britons Michael Harper and Jeffrey Wilby, both aged around 20, for the challenging but not extreme climb on Sunday, June 19, 1966.
The state of the face when they began was "ideal, indeed close to summer conditions, and the weather was perfect", Arthurs Pass National Park chief ranger Peter Croft said in a Herald report published in the days after the tragedy. The foursome were "certainly experienced enough to tackle the climb under these conditions".
The tragedy had sparked a national debate on whether the four were experienced enough, on the need for a national mountain rescue team, and on compensation for people injured or killed doing search-and-rescue work.
The Otira Face climb usually takes a day, and climbers typically descend by an easier route back to the Otira River or the Bealey River for the walk out to the Arthurs Pass road, State Highway 73.
The weather deteriorated during the Monday.
Ferguson's father had told Croft that morning the group hadn't returned. By early on Tuesday, search parties were heading for the valleys around Mt Rolleston.
By Wednesday, a Herald reporter was writing from Arthurs Pass that the foursome's survival chances were slim, although rescuers had again heard shouts from high up the now-clouded-in mountain.
"Conditions on the mountain have been bitter with almost continuous snow, a biting wind and temperatures well below zero."
The storm raged for three days.
Hopes rose temporarily on the Thursday, when a "solitary figure jumping and waving on an icy ridge of Mt Rolleston was spotted through a brief break in dense snow clouds".
But by Friday, all hope was lost, the next morning's Herald headlines reading: "Climbers given up for dead", "Search called off", "Rescue leader killed by avalanche".
John Harrison, a 34-year-old married father of two, was suffocated when, on Thursday night, a wall of snow collapsed down the Otira Slide - a shingly, rocky slope in summer, the easiest route on the mountain - and smashed into three tents housing eight rescuers.
A veteran of Himalayan expeditions, Harrison was at the time one of New Zealand's top climbers and his death shocked the nation.
He and tentmate Norman Hardie, who in 1955 was in the team to make the first ascent of Kangchenjunga, the world's third-highest mountain - had intended to camp higher on Mt Rolleston, away from potential avalanche paths, but instead stayed lower after investigating reports of shouting in the vicinity, thought to be from one of the lost men.
Hardie, Harrison and John Wilson were trapped in their collapsed tent by avalanche snow 3m deep.
Hardie said in a Herald report: "I was asleep at the time and was awakened by terrific pressure and a suffocating feeling."
"John Wilson and I were unconscious quite a while and did not know a thing until I came to as I was being pulled out of the snow, legs first. It was dark and fresh air was a great relief."
Wilson says in his 2012 book on Harrison, Joy of the mountains: a climber's life, that the tent lowest on the slide did not collapse completely, allowing its two occupants to start the new search and rescue effort.
They rapidly pulled the three men out of the middle tent, conscious but dazed from lack of oxygen.
"Norman and I were both lying on our backs. Though scarcely able to move, we managed to tear the material of the tent, through which air trapped in the snow may have filtered in," Wilson writes.
The two rescuers, digging with mittened hands, broke through snow to the tent, finding "two hands protruding through the hole in the fabric".
"They quickly scooped out around the tent's door and hauled Norman and myself, feet-first, up the long tunnel in the snow that had been dug to reach us. Both Norman and I had lost consciousness."
"When John was hauled out he was not breathing and a long attempt to resuscitate him failed."
The Herald said that in the middle tent, Hans Bohny grabbed Nick von Tunzelman's spectacles, snapping them in half, "and used a jagged edge to cut through the canvas. He then managed to punch a hole up through the snow."
Of the four Otira Face climbers, the bodies of three were recovered: Harper's from the face the next summer; and the two Kiwis from the Bealey face in 1969.
Wilson says the Kiwis may have become disoriented while trying to descend, possibly seeking help after one of their companions had been injured.
Bruce Ferguson's sister, Lorayne, now aged 68, said that after a 50th anniversary commemoration last year, the Department of Conservation had given approval for placement of a plaque and brass boot sculpture, which have now been mounted behind the Arthurs Pass Chapel. Today's service will be a dedication of this memorial.
"For the first time in those 50 years, family of one of the English climbers [Wilby] will be visiting where the events took place." Wilby's body was never recovered.
She said that in an earlier memorial, her parents, and those of a climbing friend of Bruce's, who had died on Mt Elie de Beaumont in December 1966, contributed to the construction of two bridges in Arthurs Pass National Park, one at Waimakariri Falls, the other, subsequently destroyed, in the upper White River.
Lorayne said she had felt privileged to meet and thank some of the men who had searched for her brother.