By Steven McKenzie
BBC Scotland news website, Highlands and Islands reporter
Sergeant Andy Elwood began to realise something was wrong when the moisture on his eye-lashes began to freeze.
Sqd Ldr Iain MacFarlane, Flt Lt Jane Mannering and Sgt Andy Elwood
The 37-year-old RAF winchman had been lowered into Coire an t-Sneachda in the Cairngorms to go to the aid of a climber with a broken ankle.
Moments after reaching the casualty and his four companions the weather started to close in.
Snow filled his helmet, which he had taken off to better hear what the climbers were telling him.
Then whiteout - a phenomenon where the snow-covered landscape and white snow-filled sky blend, giving the impression of being suspended in a eerie white void.
What had started - in RAF terms - as a fairly routine search and rescue was now entering the realms of the extraordinary.
This is the story of the stranding of RAF Lossiemouth Sea King XZ593 in Coire an t-Sneachda - Corrie of the Snows - last February.
The helicopter crew of Sgt Elwood, pilot Squadron Leader Iain MacFarlane, co-pilot Flight Lieutenant Jane Mannering and radar operator Flight Sergeant James Lyne had been training over Spey Bay when they got the call-out.
A climber had fallen in the corrie - a hugely popular area for climbers - on Cairn Gorm mountain.
Sq Ldr MacFarlane, 43, said: "It was a relatively straight forward job on the face of it.
"On the way we flew through bands of snow with big clear gaps in between."
It took five to six minutes to lower Sgt Elwood to the injured climber at the back of the corrie.
Sq Ldr MacFarlane said: "We flew away to give the winchman a bit of peace to prepare the casualty for winching and, as we flew back out of the corner of the corrie, became aware that conditions were markedly worse."
On the ground, Sgt Elwood put a splint on the climber's injured leg and prepared him to be winched up to the helicopter.
"My helmet allows me to have communication with the crew and Cairngorms Mountain Rescue Team, who were on their way," he said.
"I had taken it off so I could speak to the casualty and the others and it was filling with snow.
"Visibility was greatly reduced. It was a whiteout."
He added: "I noticed something in front of my face. It was irritating me and I rubbed my eye and I realised there was ice on my eye-lashes and they were sticking together."
Getting back in touch with the air crew, Sgt Elwood was warned that they were having difficulty returning to the scene to pick them up.
SEARCH AND RESCUE
Primary role of RAF SAR is recovery of downed military pilots
Westland Sea King HAR3 first entered RAF service 1978
Standby Nimrod aircraft specially equipped for SAR duties based at RAF Kinloss
The winchman said: "I started getting this mental picture that we were going to be there for a while.
"I saw one of the other members of the party was starting to suffer from the effects of early hypothermia."
The climbers had a bothy bag, a lightweight cloth shelter, and they and Sgt Elwood huddled up inside it.
He said: "These guys had prepared for something going wrong. They were well equipped."
Meanwhile, the helicopter crew were unable to navigate safely out of the corrie because of the conditions.
Flt Sgt Lyne found a boulder field - the only point of reference visible in the whiteout - to hover above.
It was decided that the safest course of action until the weather cleared was to land, but keeping the engine and rotors running.
By now it was getting dark and the crew put on their night vision goggles, however, the swirling snow made it hard to see.
But an equally serious concern for the crew was the rotor blades freezing up in the extreme cold.
The crew were discussing the prospect of shutting down when the decision was made for them.
Sqd Ldr MacFarlane said: "One of the blades shed some ice causing an imbalance and the helicopter started shaking.
"The aircraft began to lurch laterally. We shut down.
"On closer inspection the blade leading edges were sporting up to 2in of clear ice.
"We were all wearing rubber suits because we had been testing for a maritime environment so we had to go to the back of the aircraft and change into whatever winter weather gear we had."
Flt Lt Mannering, 28, said members of the Cairngorm MRT were at the helicopter within minutes.
She said: "They were absolutely fantastic. They navigated us off the mountain - where they said to go I followed. I can't praise them enough."
The rescue team had also arrived in force with Sgt Elwood and the climbers, who had been keeping their spirits up telling jokes.
The winchman, a former ambulance serviceman, said: "The winchman has to be prepared to spend time on a boat or mountain and is better kitted out for these situations than the rest of the crew.
"It was very cold that day. I don't know what the temperatures were, but I have heard it said that it was -25C or may be worse.
"I had gotten my gloves wet and my spare pair wet too so my hands were very cold.
"It was just great to see the mountain rescue team guys. Someone lent me a pair of gloves and I was offered a shot of a 15 or 20-year malt, which I declined of course."
The casualty was stretchered by foot from the scene.
From initially reaching the injured man at 1700 GMT it was six hours before Sgt Elwood's ordeal ended when he was reunited with the rest of the crew in the Cairngorms MRT HQ.
Sqd Ldr MacFarlane said: "I had, guiltily, picked at a rather tasty chicken jalfrezi while my winchman had helped to carry - and continually tend and reassure - his casualty through knee-deep snow in blizzard conditions."
Remarkably, the stranded Sea King was defrosted and flown out of Coire an t-Sneachda nine days after it set out to rescue the climber.
Heating experts de-iced the helicopter allowing it to fly to Glenmore Lodge, before it was flown to RAF Lossiemouth.
Sgt Elwood said: "The thing that stood out to me through it all was the mountain rescue guys.
"They know the conditions so well and are so physically strong. They really looked after us."