The first thing you hear is the roar. It's a terrifying sound, instantly recognizable. Your head jerks up, and you see the thundering cloud of ice blasting toward you. There's no time to do anything but race to the nearest house-size block of ice and dive for cover behind it. This is certainly what happened at 6:45 a.m. yesterday to the 20 to 25 Nepali mountaineers caught in that deadly avalanche.

Many of those of us who have climbed Everest have had this experience, in exactly the same place in the Khumbu Icefall. Usually, if you're lucky, the chunks of ice are no bigger than pebbles, and the wave of ice and snow blows over your trembling body. But not this time. Yesterday a hanging glacier above the Khumbu released apartment-size blocks of ice. The climbers didn't have a chance.

At least 16 mountaineers died in what ranks as the worst single accident on the world's highest peak. Thirteen bodies have been recovered, and three are permanently entombed in ice. No Western climbers died. Almost all of those who perished were Sherpas. As a helicopter flew four of the injured to a hospital in Kathmandu on Friday, the thumping of its blades echoed off the slopes above base camp.

View Images Mapping the killer path of Friday's Everest avalanche. Juan Velasco, NG Staff. Photograph by Mark Jenkins

"It has been devastating up here," said Todd Burleson, owner of Alpine Ascents International, one of the more successful guiding operations on Everest. "It's just a very sad, sad affair," he said by phone from Pheriche, a small village just below Base Camp in the Khumbu Valley. "Everyone is of course at a loss for what to do, how to handle it."

At present it's unclear whether climbing will go ahead on the mountain this season. It's still early in the season, and some teams will most likely want to continue their ascent. But for now, the hundreds of people at Base Camp are still in shock.

Alpine Ascents International lost five Sherpas in the accident, four of whom have been recovered. Burleson and his top Sherpa, Lakhpa Rita, flew all four bodies via helicopter to their respective villages.

"Now the process begins," said Burleson. "The process of grieving."

View Images The body of Nepali mountaineer Ang Kaji Sherpa is carried to the Sherpa monastery in Kathmandu. PHOTOGRAPH BY NIRANJAN SHRESTHA, AP

Death on the Mountain

This is nothing new in Sherpa culture. Because of their extraordinary spirit and adaptation to high altitudes, Sherpas have been used as porters on Mount Everest from the beginning of mountaineering there, and they have been dying on the mountain since the first serious attempt to climb it by George Mallory and his team in 1922, when seven Sherpas were killed by an avalanche.

View Images Relatives gather for the arrival in Kathmandu of the bodies of those who died on the mountain. PHOTOGRAPH BY PRAKASH MATHEMA, AFP/GETTY

It should be noted that Sherpas are not dragooned onto Everest. They choose it. The average income in Nepal is about a thousand dollars a year. A Sherpa can make $5,000 in three months of work in one spring. Sherpas are mountain mercenaries, in part through economic necessity. They know the risks. All of them have lost friends. They are like volunteer soldiers: They know they could die, but they still see humping loads on Everest as the best way to support their families.

Sherpas practice the most ancient form of Tibetan Buddhism, the Nyingma, "the old school," which is founded on early translations of scripture from Sanskrit into Tibetan over 1,200 years ago. Nyingma is a mystical version of Buddhism, the power of nature embodied in protective gods. Jomo Miyo Lang Sangma is the resident deity on Everest, a goddess who rides a red tiger. To many Sherpas, it must feel as if Chomolungma, goddess mother of mountains, has taken her revenge once again.

Most of the dead will likely receive a traditional Sherpa funeral. Lamas are called immediately to be close to the body and pray for the soul of the deceased. The body is later cremated, the ashes mixed with clay, and a small sculpture formed, called a tsatsa. This sculpture will be placed in a monastery, or chorten, where it can be visited by family and friends.

During this process, prayers are said for the deceased by the family and by lamas, and every evening an offering of tsampa is put on the coals of the hearth. After 49 days, the soul of the deceased will have passed through the time and space between lives, and according to the Nyingma, shall be reborn.

A Bad Omen

Certainly some Sherpas will see this tragedy as a bad omen in the short term, and will leave the mountain for the rest of the climbing season. And no doubt some climber clients will come to the same conclusion, abandoning their hopes for ascent and hiking out. How this will affect individual teams is yet to be determined, but there will undoubtedly be attrition and consequent consolidation.

"It is too early to predict what will happen," said Jiban Ghimire, owner of Shangri La Trekking, a company that works with guides and outfitters in Nepal. "No one is up on the mountain right now. Everyone is back down at base camp reassessing."

For those clients, Sherpas, and guides at base camp who intend to stay and climb, the current discussion is about whether the track up the Khumbu should be rerouted-and if so, where? This has been a contentious topic for years. Presently the ropes and ladders are strung up the left-hand side of the icefall, where there is a relatively smooth path through the crevasses and seracs.

View Images A Buddhist monk lights candles in front of the casket for Ang Kaji Sherpa at the monastery in Kathmandu. PHOTOGRAPH BY PRAKASH MATHEMA, AFP/GETTY

This particular track is exposed to fewer dangers in the icefall itself-looming, apartment-size seracs and wide, 100-foot-deep (30 meters) crevasses, but has the distinct disadvantage of passing directly beneath the hanging glaciers that are suspended from the West Shoulder. It was the collapse of a gigantic serac from these hanging glaciers that caused the recent tragedy.

Over the past 50 years, there have been other routes up through the Khumbu Icefall, an obstacle that must be overcome in order to gain the Western Cwm, the upper mountain, and the summit via the Southeast Ridge. The route through the icefall cannot pass along the right-hand side, because it too is exposed to constant falling ice from above.

The only other option is a treacherous, zigzagging course directly up the middle of the glacier. This route has been avoided the past few years because of the 50-foot-wide (15 meters) yawning crevasses that must be bridged and the enormous ice walls near the top of the glacier that must be surmounted.

Neither the icefall nor the hanging glaciers above it, nor the entire mountain itself, can ever be tamed. It is a merciless mound of ice and stone strictly governed by the principles of tectonics and climate and most of all gravity, the ultimate equalizer. The icefall will always be a perilous and completely unpredictable battlement on Everest. If you want to climb Everest from Nepal, there is no way around it. (Note: Some have talked of a future chopper service that would jump climbers over the Khumbu, from Base Camp up to Camp 1.)

View Images The daughter of Nepali mountaineer Ang Kaji Sherpa cries after the death of her father. PHOTOGRAPH BY NIRANJAN SHRESTHA, AP

More than 4,000 people have summitted Everest (fewer than 200 without supplemental oxygen), and about 200 lives have been lost on the mountain. This tragedy, just like all the previous tragedies, will not stop climbers from around the world from coming to Everest, nor will it stop Sherpas from choosing a very dangerous livelihood. Which means, indisputably, that death will always be part of the highest mountain on Earth.