At first sight, the Cairngorms, where Jane Thomas died last weekend, seem disarmingly benign. From the A9 near Aviemore they appear as a distant lump, devoid of peaks and crags. Their most striking feature is the deep cleft, known as the Lairig Ghru, which divides them neatly into two. Even when streaked by snow and capped by storm clouds, as they have been for much of this week, it is hard to imagine them as killers.

Closer to, however, they assume a different aspect. Hillwalkers and mountaineers know only too well that the Cairngorm plateau, where Thomas and her companion, George MacEwan, fought for their lives, can be the most hostile place in Britain, an Arctic-style tundra scoured by bitter winds, often waist-deep in snow. It is a place notorious for eroding safety margins and punishing mistakes.

Thomas, 28, and MacEwan, 33, both fit and experienced, had planned to tackle an ice climb in Coire an t-Sneachda, one of the north-facing corries of the Cairngorms, barely a mile from the ski lifts that carry skiers close to the summit of Cairn Gorm. The climb took longer than intended. Thomas found the upper section particularly hard and MacEwan had to rig up a rope harness to help haul her to the top. By then she was cold and close to exhaustion. The two climbers' problems were compounded by an archetypal Cairngorm blizzard. The storm arrived six hours earlier than forecast, bringing gusts of up to 90mph.

In theory, Thomas and MacEwan had only to head north for a mile to reach the ski lift where they could descend to safety. It was now that they made their fatal error. Somehow misreading their compasses, they set off not north but south. By the time they realised their mistake they had all but consumed their remaining energy and Thomas collapsed as they attempted to retrace their steps.

MacEwan dragged her for a mile before being compelled to go for help. He stumbled into the Cairngorm car-park in the early hours of Monday and, suffering from exhaustion and frostbite, was unable to give the waiting mountain rescue team a clear account of where he had left her. By the time she was found it was too late. As the rescue co-ordinator, Chris Barley, observes, she and MacEwan were unlucky. It was, he adds, 'a mistake we could all have made', not least in the Cairngorms.

The death of Jane Thomas, however, is unlikely to deter other walkers and climbers, myself among them. That is despite this week's implicit warning from the chief constable of the Highlands, when he observed that more people had died this year in the mountains in his region than on the roads.

The statistics also reveal an apparently disturbing trend: mountain deaths in Scotland, around 30 a year through the Eighties, rose to 44 in 1991, 43 in 1992, and 51 so far this year. The highest proportion of accidents occur in the winter, when mistakes are more likely to be penalised. So what is it about the Scottish Highlands, and the Cairngorms in particular, that provides such a lure?

In the summer, the attraction is perhaps easier to see. The Lairig Ghru, so striking from Aviemore, is the highest and longest mountain pass in Britain, taking hillwalkers into the heart of the Cairngorm range. To strike up from the Lairig Ghru on to the plateau 1,000 feet above is to find yourself in the most barren landscape of Britain. The stony, undulating terrain, is intersected by hidden lochs ringed with sombre cliffs. It is the home of the ptarmigan, the peregrine falcon and little else. If the Cairngorms have a wild beauty in the summer, in the winter they are awe-inspiring. The lochs are blanketed with up to a foot of ice, the surrounding buttresses festooned with fantastical ice confections wrought by the wind. On clear days the plateau has a magical stillness where voices carry for miles. At your summit you survey a landscape that seems timeless in its desolation.

These, however, are rare days. Far more often the skies are leaden, the plateau shrouded in mist. You steer by map and compass, often with no view other than your partner a few steps away in the murk. The wind intensifies the higher you go, accelerating as it funnels up the mountainside.

Once, I was nearing a summit in a gale when a gust knocked me to the ground as if I had been struck by a giant hand. Even so, I understood what the pioneering Scottish winter mountaineer Bill Murray meant when he wrote of feeling akin to 'a tiny speck swallowed up in an environment incomprehensibly great. Here we knew what it meant to be alone, yet to feel distant kinship with the gods'.

Most Independent readers would, presumably, choose less perverse pleasures. There can be no denying that winter mountaineering is dangerous. Indeed, the more honest of its devotees will admit that risk is intrinsic to its appeal. But the rationale of any risk sport lies in managing the danger and reducing the risk, which also entails managing your own fears, as well as savouring the consequent sense of relief.

This is undoubtedly a serious business. For hillwalkers like me, moving inexorably through middle age, it is essential to be fit. I am already training on my cycle and step machines for my next excursion to the Highlands in February. I am usually appalled by the pain at the start of each trip but fight through it, since the best way to keep warm is to keep moving, so that the body generates its own heat supply.

Selecting the right clothing and equipment is another key. My generation has clear advantages over Bill Murray, who described how his clothes froze around him like armour. Today's walkers dress more snugly in synthetic vests and long johns, windproof jackets and breathable waterproofs made from fabrics such as Gore-Tex or Paramo, which channel sweat away from the body - a prerequisite to staying warm. Ice axes and crampons (spiked plates that attach to the soles of your boots) are lighter and tougher than in Murray's day.

Most vital of all is to know how to navigate, for the Cairngorm plateau sets a more demanding test than any other British range. The most daunting condition is known as a white-out, when snow is falling and ground and sky merge as one, requiring an impressive act of faith to go where your flickering compass needle bids you.

In bad weather the key technique is known as 'aiming off', where instead of making directly for the summit you aim first for a larger, more identifiable feature and head in from there. Last winter I set off for Beinn a'Bhuird in the heart of the plateau. My partner and I first found the rim of the mountain's giant eastern corrie and edged along it, doing our best to ignore the 1,000-foot drop. We struck for the summit when our map showed that it lay due west, and had our reward when the diminutive summit cairn loomed right on cue.

Walking in the Cairngorms means protecting your safety margins, too. There is little room for error as there are few places to shelter if you are overtaken by darkness or bad weather. From Beinn a'Bhuird we had hoped to reach a second peak, Ben Avon, but realised we had no time to spare if we made even a small route-finding mistake and so made a judicious retreat, resolving to return another day.

It is all too easy in retrospect to identify the navigational mistake that Jane Thomas and her companion made, to which tiredness and the ferocity of the storm contributed. This accident has been refreshingly free of the customary calls for greater regulation of the sport. Since the disaster of 1971, when six schoolchildren died in a Cairngorm blizzard, mountaineering bodies have warned against regarding the mountains as a giant adventure playground and educational authorities are now more cautious. Jane Thomas undoubtedly understood the risks she ran. They were the risks of a mountaineer; no more, no less.

(Photographs omitted)