Capt. Mike McKechnie is about as typical a young British Army officer as you could find -- perhaps more the gung-ho than the reflective type. On New Year's Eve 1979, aged 29, he was organizing the British Army ski team at Andermatt in Switzerland when he was invited by another young Englishman join on a deep-snow tour the following day.

It proved a deadly trip, interrupted by a horrendous avalanche sweeping down the mountain, a story that I tell here as a warning to American skiers -- particularly the good ones -- who may be unaware of the potential dangers of the European Alps. It is so often the more skilled skiers, thinking they know better, who take the most foolhardy risks in pursuit of that special slope of powder.

The other Englishman, Michael de Prett Roose, was himself sk,2 sw,-2 ld,10 an expert skier who had lived in Andermatt for some years, and the party was to be led by an accomplished local guide, Ernst Renner. The previous day one to two feet of new snow had fallen, and the Swiss weather service warned of "an increase in the danger of avalanches." But because the warning specified primarily north slopes, and they would be trekking across east-facing slopes, the group leaders decided to risk it.

Accordingly, at 8:35 a.m. on Jan. 1, they set off for the 7,000-foot-high Pazolastock, near where both the Rhine and Rhone rivers rise and in an area renowned for avalanche danger. During the night, unknown to them, the wind had veered round, making the peril on the slopes for which they were heading that much graver.

The party consisted of six: Renner; de Prett Roose and his wife Karin; her teen-age son Nicholas, and another Brit, Mark MacKenzie. All were wearing SKADI bleepers, designed to transmit the location of skiers buried by an avalanche, and they were otherwise properly equipped. After traversing a first ridge, Renner warned that the next bit would be tricky. Accordingly, they spaced out, loosened their bindings and unlooped their poles. De Prett Roose was leading across a small valley when, without warning, cracks opened above the group, and a small slide came down.

McKechnie was caught, and recalled, "When the avalanche came to a halt, I was buried right underneath, with a sensation of being set in concrete. I could not move my head one millimeter, or even a finger. There was a dim light, so I know I wasn't far beneath the surface. My breath created a cavity; then in a horrible way I could see it ice in front of me when my breath reached the limit of the area it could melt. Then I ran out of oxygen and blacked out. The next thing I remember is seeing light as a hole was cleared above me and air came in. The others had found me."

When dug out, McKechnie was suffering from hypothermia and shivering violently, so they put him in a special inflatable anorak, which, he said, "made me look like the Michelin-man ad." It almost certainly also saved his life.

Realizing it was too dangerous to retrace their footsteps, the party set off again, rather nervously, with the guide, Renner, leading. Suddenly Renner shouted, "Look out!" Facing up the slope, McKechnie saw "an enormous, billowing, horrific cloud of airborne snow coming sweeping down the mountain. In that split second it hit me, engulfed me and I was swept away like a leaf in a thunderstorm -- crashing, tossing and rolling over and over, head over feet. It seemed to go on and on. I remember a terrible falling sensation and then a bang as I landed on my back."

When the avalanche stopped, McKechnie found himself miraculously on the surface, he thinks as a result of the Mae West effect of the inflatable anorak. He had two broken ribs, the force of the avalanche had ripped away his poles and gloves, and he was left with only one broken ski.

This second slide had been on a gigantic scale; he estimated it at about 1,000 yards across the break at the top, and that he had been carried the same distance down the mountain. (Later investigation showed that it had been started by the collapse of an east-facing cornice, probably brought down by the shifting wind.)

There was no sign of the five other skiers. Yet, despite his painfully broken ribs and hypothermia from the first avalanche, McKechnie set his SKADI to "receive" and tried to dig for them. After about an hour and a half of abortive efforts, he decided to give it up and walk for help.

It was, he said, "the most terrible decision I have ever had to make, because I was leaving them all behind, probably still alive at that stage, to die. I will never forget that moment for the rest of my life."

By this time it was about 3:30 p.m., and the light was already failing. Through virgin snow often up to his thighs, and in bitter cold, McKechnie floundered blindly downhill for another couple of hours, with his one broken ski. On the verge of collapse, he stumbled on a mountain hut in the dark; by a second incredible stroke of good luck, the door was unlocked. He spent the night in the unheated hut, walking up and down to prevent himself from falling asleep.

At dawn he set off again, found a path and eventually reached a village restaurant. A rescue helicopter was called out, plus 25 avalanche dogs, and -- though more dead than alive -- McKechnie went back to the scene of the disaster to try to locate his companions. After hours of digging, Renner and the three de Prett Rooses were found dead; amazingly, MacKenzie was alive, after being buried 20 hours. Lying on his back, though with a hand and foot protruding, he had been cemented immovably in the snow.

Although part of the exposed limbs had to be amputated because of frostbite (snow acts strangely like a thermal blanket), MacKenzie survived. McKechnie, now a major in the British equivalent of the Pentagon, jogs nine miles to and from work every day and keeps on skiing. As well as being a remarkable story of survival, and determination, their experience also tragically represents how so many avalanche accidents happen.

After coming close to seme horrendous slides helicopter-skiing in high-risk terrain in the Canadian Bugaboos, I personally became fascinated to learn more about the terrifying "white death" that lies in wait for every unwary skier.

What causes avalanches, how many victims survive them, and what can be done to avoid them?

There are two basic schools of thought. One is that accidents are almost always the result of human error -- somebody's skis breaking the balance on an unstable slope. The other is that they can happen anywhere, where least expected.

All that is certain is that every year they come down where there are mountains, and have been doing so since time immemorial.

snow is awe-inspiring. Pressures of 22,000 pounds per square inch have been recorded, and speeds of more than 200 miles per hour. I have watched mature firs in the Utah Rockies splintered, like matchsticks, and a car tossed through a first-floor window in a lodge at Alta.

Some U.S. experts consider the Europeans to be too lax about avalanche safety precautions. I have always been impressed by counter-avalanche measures taken in American resorts. In Alta, with its heavy snowfalls -- and therefore great slide danger -- the first snow ranger to keep watch on avalanche dangers was appointed back in 1937, and today wide use is made of recoilless artillery to bring down dangerous cornices.

Sometimes skiers are encouraged to watch avalanche control from a safe distance, while it is explained for their education. This kind of instructive public relations approach does not seem to exist in Europe.

Discipline in American resorts is also generally more forceful. Skiers who are caught outside resort boundaries often have their lift tickets torn up. This does not happen in Europe, where danger is considered the responsibility of the individual. On the other hand, the more expansive European ski areas are much more difficult to patrol. Because of contours and the nature of the snow itself, Colorado is relatively "safe."

Topography and climate are what make some areas more danger-prone than others -- for instance, Austria's Vorarlberg region around Zu rs and Lech and France's Val d'Ise re-Tignes. Guides and safety personnel in such resorts have to be -- and generally are -- highly qualified. But an avalanche can happen almost anywhere there is an incline.

According to Swiss statistics, avalanche deaths nationally average only about 26 annually, compared with 1,200 deaths on the roads, and 50,000 other skiing accidents, and the proportions are roughly the same for France and Austria. A worrying factor for rescue services is that the potential hazards are escalating in Europe, and the past two years have been particularly bad. By the end of the 1985 ski season, 55 people had been killed in Switzerland alone, the highest toll since 1950-51.

"Every year," Ernst Frautschi, a mountain guide in the Bernese Oberland of Switzerland, told me, "more and more tourists want to escape from crowded pistes and ski sauvage, but they know nothing about nature and don't understand the danger. They should never go without a guide."

After a while, every experienced off-trail skier has had his or her disaster story, or heard a dozen others. In general, they tend to confirm the thesis that slides are started by human error, by the victims themselves or by someone higher up the slope.

On our helicopter group in the Canadian Bugaboos was Willy Bogner of the famous Munich ski-wear firm, former Olympic skier, stunt director for James Bond movie ski sequences, producer of some staggering ski films and one of the most dazzling skiers I have ever seen. But he had been long haunted by an accident 20 years ago in a steep valley near the Swiss resort of St. Moritz that had already claimed the life of one expert skier.

Bogner had been filming a group of Olympic skiers, including his fiance'e Barbie Hennelerger and the American racer Bud Werner. Slab snow, frozen during the night, broke away from its base above them. Bogner, in the lead, was able to ski out laterally; Hennelerger and Werner both tried to "schuss," but were overtaken and killed.

Even guides can get it wrong. Pressed by clients who wanted to do a powder run down the Stalden, near the Swiss resort of Gstaad, a young friend of mine set off to make it safe the night before by bringing down a cornice with explosives. His first grenades failed to budge it, so he tried lower down. His own weight was enough to bring the cornice down on top of him, and he was found dead in snow "not deeper than a table."

Because of enormous pressures, the lightest powder is converted into the consistency of concrete. Hence skiers about to be caught should always jettison poles, and try to ball up their fists in front of their face so as to be able to burrow an air chamber under the snow.

Statistics indicate a 1-in-3 chance for the survival of buried skiers. Twenty percent die almost immediately; for the rest, provided there are no fatal injuries, a victim has an 80 percent chance of survival if dug out at once. After one hour, the graph sinks to a 40 percent chance; after two hours, down to 20 percent; after three hours, 10 percent.

On the other hand, the records reveal some remarkable survival stories. In Macugnaga, Italy in 1972, a Canadian girl was found uninjured by a rescue dog after 44 hours of entombment; in 1965, in British Columbia, a 32-year-old was dug out alive by a bulldozer after 79 hours. One of the most remarkable survivals must be that of the Swede hit by an avalanche while out hunting partridges. For seven days he existed by eating his raw partridges and drawing air along the trunk of a birch tree against which he had been forced. As McKechnie's fellow survivor discovered, snow acts mercifully as an insulator.

In the 17th-century Alps it was generally held that avalanches were caused by witches. In 1936, however, the Swiss led the way by founding the Federal Institute for Snow and Avalanche Research at Davos to put things on a more scientific basis. The only establishment in the world dedicated solely to avalanche research, it sits atop the Weissfluhjoch, above a series of avalanche fields and surrounded by fences and barricades. Casual visitors are gently deterred.

Inside the institute there is a "Dr. Strangelove" atmosphere, with fur-clad scientists beavering away in refrigerated laboratories. The director, Dr. Claude-Francois Jaccard, a physicist, believes that most accidents are caused by good skiers: "You can't absolutely predict an avalanche at 15:15 hours, but you can predict tendencies -- on the north slopes more than any other. It is very rare that there was no warning."

Annually the institute puts out an analysis of accidents, containing with depressing regularity reports like the following: " . . . On the way to his almost certain death 'X' passed 3 general avalanche warning notices and also 4 signs informing him that the run of his choice was closed."

About 80 percent of avalanches occur after new snowfalls, Jaccard noted, explaining to me the different kinds: the airborne powder chute, which, usually falling from a great height, can wreak the most devastation; and the break-away slab slide, most commonly encountered by skiers (such as the one that engulfed the McKechnie party).

Contrary to widely held beliefs, a fall in temperature leads as often to avalanche conditions as a sudden rise, like the onset of foehn weather, the warm wind of the Alps, or the chinook wind in the Rockies. Steepness can also be an exaggerated factor. On angles above 50 percent avalanches rarely occur, because the snow can't build up, and while most slides start on slopes of between 30 degrees and 40 degrees, they can occur on gentle inclines of 20 degrees or even less. Perhaps the greatest enemy is always the wind-driven slab.

In Jaccard's laboratories much microscope work is carried out on snow molecules, coming in more than 6,000 variations of beautiful stars with Velcro-like hooks that bond each snowflake. When wind or a change in temperature or some other factor occurs, the hooks decay; instability sets in, and -- bang.

New radar techniques are being developed to detect different strata of snow, as well as the "lawino," a tube that can detect human smell one yard below the surface. In collaboration with U.S. scientists, research is also being done into the forecasting of avalanches with acoustic probes.

"Bleepers," such as the SKADI used by the McKechnie party, are constantly being improved, but still avalanche dogs, huge and fierce Alsatians, are rated the most reliable means of locating victims in the European Alps. (The skill of trained dogs, quite uncanny to watch at work, was apparently discovered quite by chance in 1937 when a Swiss mongrel terrier called "Moritzli" dug out a skier alive.)

Acid rain provide the most frightening long-term worry for the institute's forestry experts, for trees provide nature's greatest antiavalanche measure. Another of its roles is to prepare danger studies for individual areas, and Jaccard showed me one commissioned for one of Switzerland's fastest expanding reports. Several new chalets lay well within the "red" danger zones. "I wouldn't like to sleep in any of them!" said Jaccard.

* What can the off-trail skier do to avoid being caught by the ever-lurking white death? One French expert has a simple formula: "After a large fall of snow and a temperature above freezing, stay in the sack and dream of better times!"

But there are certain golden rules:

*Watch for avalanche warnings, and never disobey them.

*Never go off into off-trail territory with less than two others, and preferably a qualified guide; and tell someone where you are going.

*Never follow unknown tracks.

*Study the terrain, learn about snow behavior and watch out for unstable conditions.

Avoid wind-blown cornices, and beware north slopes.

*Watch out for sharp rises in temperature.

*Take SKADI bleepers with you; or, ideally, your own tame Alsatian!

If you have to cross an avalanche slope:

Space out between skiers.

*Slacken your bindings, and free wrists from pole loops (poles can cause appalling injuries, and prevent you from creating that air cavity).

*Stick to the ridges and avoid hollows.

If caught:

*Get rid of skis and poles.

*Try to roll to the side or "swim" on the surface.

*Try to keep calm when covered; panic consumes valuable oxygen, and above all don't waste breath by shouting.