It was alleged that Flt Sgt Stephen Henderson failed to comply with recognised safety regulations and ignored avalanche warnings when he led 26 skiers down the Riedbergerhorn mountain more than two years ago.
Three companions were engulfed by the snow slide during Ex Snow Eagle, an RAF adventurous training exercise in alpine ski touring near Oberstdorf.
Two airmen were quickly dug out and survived, but the third, SAC Paul Mahoney, 26, had asphyxiated by the time he was found.
The prosecution argued that as chief ski instructor, the Senior NCO’s conduct had been “reprehensible”.
“SAC Mahoney was killed by an avalanche as he was descending a slope under the direction of Flt Sgt Henderson,” prosecutor Lt Col Mike Culver told a court-martial in Sennelager.
“It was grossly negligent. It could be described as reprehensible.”
The Flight Sergeant had pleaded not guilty to the charge of manslaughter stemming from the skiing accident on February 4, 2010.
Chris Hill, defending, told the court that backcountry skiing involved an element of risk-taking and that the accused had viewed the slope as shallow and not avalanche prone.
“This is adventurous training and not a leisure facility. The purpose was to make a journey and hopefully get to the next hut,” he said, adding that “rules are not to be adhered to slavishly.
“This is risky and adventurous stuff in a controlled environment”.
He said that the accused had carried out risk assessments and set high standards.
“He was not a mountain guide – very far from it,” said Mr Hill.
“If safety is going on in his head, how can he be grossly negligent?”
At the end of the four-week trial, during which evidence was heard from expert witnesses on both sides, the six-member board acquitted the accused after deliberating for just over an hour on July 19.
During the trial Lt Col Culver accused Flt Sgt Henderson of having the “uncontrollable” group descend the mountain’s north slope in one go, instead of one by one, putting an unnecessary stress on the snow pack and adding to the likelihood of an avalanche.
He also alleged that the defendant failed to select an appropriate descent route and that the slope was too steep for the limited ability of the group.
The avalanche warning issued on that day for the north slope was level 2 rising to level 3 and advised avoiding slopes of 30 degrees or more.
The group was at about 1,500m when the avalanche struck but the degree of the slope was no more than 30 degrees.
“The prosecution says Flt Sgt Henderson failed to follow warnings and advice set out in that forecast,” said the Colonel.
“On arrival at the ridge he noticed a crack in the snow, whumpf sounds and a cornice – further warning signs of a [pending] avalanche.”
Lt Col Culver added that ski touring was “inherently challenging” but that the training could have been achieved more easily on the south side of the mountain.
Defence counsel Chris Hill said the prosecution’s case was “simplistic” and that the exact cause of the avalanche could never be established.
“It’s a serious charge. The prosecution have set the hurdle very high,” he said, suggesting that his client could have been charged with the lesser military offence of negligently performing a duty.
“Is this man a chance-taker, a corner cutter? He has a completely clean record, he’s never been in trouble in his life… he’s squeaky clean.
“When the military police investigated, they took the way Snow Eagle was constructed to pieces. They failed completely to find anything on Flt Sgt Henderson.
“[Prior to the incident] he wasn’t out drinking, he wasn’t in bed, or in the coffee bar… he was doing everything he could have done [in preparation].”
Although experienced in conducting adventurous training, the defendant – with a 17-year Service career – was not experienced in ski touring per se, the court heard.
Flt Sgt Henderson had been given no induction, had no local knowledge and had been tasked with getting the group ski touring in just three days.
Mr Hill said that although in the morning of that day there was a level 2 avalanche warning, “66 per cent of skiing is done when the avalanche warning is at level 3".
“There was a beautiful blue sky… a perfect day for skiing,” he said.
“It is not a mountain, it’s a hill. The slope is hardly the face of the Riedbergerhorn.
“In his eyes it wasn’t an avalanche-prone slope.
“He did a rutschblock test and jumped up and down on the snow. How much more was he supposed to do? The snow was stable.”
The court heard from two experts that, although the avalanche may have been triggered by the backcountry skiers overloading the snowpack, it may also have been triggered naturally.
Mr Hill added: “Everybody has to live with the consequences… it’s very sad.
“We will probably never know really what occurred. This is a criminal trial, not a board of inquiry.”
The deceased, Senior Aircraftman Mahoney, was with 15 Squadron RAF regiment based in Honington.