Accident revives arguments on wisdom of skiing off-piste: Chris Gill, Skiing Correspondent, considers the possible causes of the weekend's tragedy

THERE, but for the grace of God, go I. That will be the reaction of most keen skiers to Saturday's tragedy in the mountains above Tignes. It is certainly mine.

The weather was fine. The snow was perceived locally as stable. The party of British doctors was skiing with a guide from Val d'Isere's Snow Fun ski school, as I and countless other experienced British skiers often do. So what went wrong?

Last night, not surprisingly, no one in Tignes or Val d'Isere was in a hurry to talk. But the available evidence suggests that the avalanche was not of the powder snow variety that most skiers are alert to - where fresh snow mounts up to the point where it loses its tenuous hold on the mountainside and slides down, normally soon after the snowfall.

This is more likely to have been a slab avalanche, where snow is packed by high winds into a dense form that seems solid and cohesive but is liable to crack. The strong winds that create the conditions for slab avalanches were present last week. Changes in temperature or other disturbances, including the presence of skiers, can trigger the slide.

When a slab avalanche occurs, it can affect a wide slope all at once, effectively removing one option for the threatened skier - that of skiing across the slope, out of the way of the advancing wall of snow. The remaining option is to try to keep ahead of that wall, and to try to keep on the surface of the snow once it catches up.

The party was skiing in the Col du Palet area, directly west of Val Claret, the part of Tignes at the foot of the lifts up to the Grande Motte glacier area. For piste skiers, it is an amiable area of blue runs. For off-piste adventurers, it is the launching point for an exciting although apparently not difficult excursion to Champagny, one of the resorts making up the La Plagne ski area. The run to Champagny presents avalanche risks, but not usually of the windslab variety.

This accident, the worst for some time involving British skiers, will revive arguments about the wisdom of skiing off-piste - that is, outside the ski runs supervised by the resort authorities.

The marked and patrolled runs of a ski area - the 'pistes' are opened to skiers only when snowfields threatening to avalanche have been triggered or stabilised. Off-piste, it is a different story.

Thanks to the lie of the land, the ski area shared by Val d'Isere and Tignes is unique in the Alps in the quantity of off-piste skiing that is easily reached from its lift system. The off-piste runs are well known, and skied by large numbers of people. But they are as dangerous as off-piste runs anywhere, and the resorts deal with this by displaying signs at departure points, declaring the off-piste areas closed and dangerous.

When you step under the rope and ski past the warning signs, you do so knowing that you are placing your life in the hands of the person leading the party. You do it not for the thrill of taking an unnecessary risk, but for the thrill of going into high, remote places where you can go only with the aid of skis.

In this case, the person leading the party made a mistake, and paid for it with his life.

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