On a winter's day exactly 25 years ago, members of two of Scotland's mountain rescue teams were mustering at Ben More Farm near Crianlarich in Perthshire.
The Killin and Lomond teams had been called out after a report that a woman had fallen on Ben More.
It was a routine enough call - but one that was to end in one of the worst tragedies to befall mountain rescue in Scotland.
On the day of the accident, the Killin team had been called out to recover the body of a climber who had collapsed near Inverlochlarig. They were then diverted to the 1,174m (3,851ft) Ben More to help a woman who had apparently slipped on the steep northern slopes of the snow-covered Munro.
A Wessex helicopter from RAF Leuchars picked up two more team members - including team leader and local police officer Sgt Harry Lawrie - to drop them near the top of the hill.
As the helicopter attempted to land, its tail rotor hit a rock, causing it to crash and slide 1,000ft, narrowly missing members of the team already on Ben More.
Bob Sharp, former leader of the Lomond rescue team, said he was standing next to Sgt Lawrie's wife at Ben More Farm when they both witnessed the crash.
He told the BBC Scotland news website: "The two guys were about to get out when the rotor blade banged the hillside and the helicopter spiralled into the air.
"They had apparently unclipped from there straps. Harry Lawrie fell about 200ft."
Mr Sharp said the second rescue team member, PC Ian Ramsay, was only saved after his ice axe loop snagged and prevented him from falling.
In a blog post about the accident, David "Heavy" Whalley, a former member of the RAF Leuchars Mountain Rescue team, said he had spent the weekend climbing on Ben Udlaidh when he saw the helicopter fly overhead.
He wrote: "It was a wonderful winter's night and we watched the helicopter as we drove down the road to Ben More, we saw a flash as the helicopter hit the mountain.
"It was surreal like a film set but it was real and we knew that a disaster had happened."
The members of the Killin team who were already on the hillside pulled PC Ramsay and the aircrew from the burning wreckage. PC Ramsay and winchman Mick Anderson were seriously injured.
Mr Whalley added: "It was an awful night and in the end the Killin team carried their team leader off the hill - a tragic event... A Sea King came in for the other casualties."
Two rescue team members, Billy Stitt and Stewart Inglis, later received the Queen's Commendation for brave conduct for their actions - as did the the helicopter pilot Hugh Pearce.
But the work was not over for the Killin mountain rescue team and the following day they returned to Ben More to find the fallen walker. Her body was found at the foot of a snow slope, with a new set of crampons in her rucksack.
A memorial to Sgt Lawrie was later erected on Ben Ledi, near Callander.
A spokesman for the Killin Mountain Rescue Team said a "small group" of Sgt Lawrie's family and closest friends would mark his death at the memorial.