By Steven McKenzie
Highlands and Islands reporter, BBC Scotland news website
Heavy was serving at RAF Leuchars at the time of the disaster
Mountain rescue veteran David Whalley hates to admit it but when he took a call about Lockerbie he thought it was a joke.
It came on his first few hours of Christmas leave from RAF Leuchars.
He said: "There was an old saying before we went on leave: 'Do not give me a call unless a Jumbo jet crashes in the mountains'."
The RAF mountain rescue team member's experiences at the scene of the atrocity would scar him for life.
Better known by his nickname Heavy, he has decided to talk publicly to highlight the role of military and civilian MRTs and search dog teams.
He said: "Many people do not realise they were heavily involved in the Lockerbie disaster.
"Very little has been written or spoken of what they did. This is part of their story."
On the afternoon of 21 December 1988, Heavy was preparing to be reunited with an old flame who was in the process of leaving her husband.
Not long after meeting her off a train, he took a call from his deputy.
Heavy said: "He told me I had to come in to work as a Jumbo jet had crashed.
"I thought it was a wind up and put the phone down. He was back on the phone in a second. 'Put on the telly, see for yourself,' he said.
"I looked at the telly, it was a like a dream, a nightmare."
Trained primarily to deal with aircraft crashes, mountain rescue teams and experts stationed at Leuchars in Fife, RAF Leeming in North Yorkshire and RAF Stafford in Staffordshire were scrambled.
Heavy was appointed as one of four senior team leaders to co-ordinate the search for survivors, victims and the black box recorder.
One of the immediate concerns was a mid-air collision as helicopters arrived from around the country to offer assistance.
Heavy said: "Communications were non-existent with the outside world, the early satellite phones had broken down and landlines were severely damaged by the crash.
"Somehow we managed to set up a landing site for the choppers and got some type of control into search areas, this was extremely important for flight safety."
He added: "Our boss had arrived, a local boy from Greenock home for Christmas. He was ex-helicopter and the ideal man.
"Local mountain rescue teams had also arrived and we had to say to them there was nothing we could do. It was too dangerous and we had to wait until first light.
"We knew there were casualties out there, but there were fires and all kinds of things going bang and in the darkness. We were just going to kill people if we let them on to the site, but it was very hard to keep back people who desperately wanted to help."
Heavy attended the crash of a Chinook in 1994
With first light came a detailed search of the expansive crash site.
Moved by the professionalism and dedication of the search teams, emergency services and volunteers including the WRVS who laid on meals for the searchers, Heavy and his colleagues were chilled by the actions of a minority.
He said: "Some criminals had come into the area robbing the casualties and their belongings. The police would tell you that did happen.
"Man's inhumanity to man was all around, how could people do this? How could anyone carry out such a crime? All these questions went through our heads."
It had also become quickly evident that Pan Am 103 had been brought down by an act of terrorism.
Heavy said: "We were very angry because we knew straight away when we were shown the maps and saw secret service guys looking for evidence that this jet had been blown up in the air. We knew this was a terrorist attack.
"The guys were in the hell of it. It was very hard for the guys from the Borders and Tweed Valley teams.
"This wasn't a mountain incident which most were used to dealing with, this was a crime.
"Our guys were putting jackets down over kids. There were Christmas presents lying around. It was awful. There were no good news stories."
The military MRTs were stood down after three days, but civilian teams remained at the scene for many days after.
Heavy said: "The local teams worked with the search dogs for weeks after we left. How they coped I will never know.
"The dogs and their handlers worked for weeks searching for human remains in the crater.
"On leaving we handed in the crash maps to the police. Every casualty plotted along with the wreckage, it brought the enormity of the tragedy to the fore."
The following month, Leeming and Stafford were called to aid survivors from a British Midland Boeing 737 bound for Belfast that crashed onto the M1 near the village of Kegworth, Leicestershire.
Please tell Scotland, thank you
The accident killed 47 people.
For Heavy, the days at Lockerbie took a toll on his health.
He was off work ill for three months and his relationship with his girlfriend broke down.
Heavy, who was later among the first on the scenes of a Shackleton aircraft crash on Harris and of a Chinook helicopter on the Mull of Kintyre, said: "For a long time I had nightmares, limited sleep and terrible mood swings.
"It took a very long time to get back to 'old me'.
"There was limited advice on how to handle these problems. The attitude then was that we were hard mountain rescue men, we could handle problems, at least we thought we could."
Now retired from the RAF after latterly serving at RAF Kinloss in Moray, he is coming to the end of taking a year out where he made lecture tours of the USA and is planning to join a civilian mountain rescue team in the Highlands.
Heavy said: "After the lectures people came up and say: 'Please tell Scotland, thank you for what they did for Americans at Lockerbie'."