Some of those 200 who failed never made it down off the mountain. The thin air and extraordinarily perilous conditions near the summit make retrieval of corpses nearly impossible. There are some frozen corpses that have lain on the sides of Everest for decades, a mute testament to the power of the mountain, and a warning to those who dare to try for glory.

The first officially recorded summit of Everest was made by Sir Edmund Hillary of New Zealand and Tenzing Norgay, a Sherpa from Darjeeling, India. They ascended Everest's summit on May 29, 1953 and became instant mountaineering legends.

Allan Thomas knows the dangers and the allure of Everest all too well. On his summit bid in 2009, a 48 year-old man from the Czech Republic and a 29 year-old climber from Canada both died. Once climbers enter the so-called “death zone” of Mount Everest, or the area above 7000-8,000 meters (23,000 -26,000 feet) in altitude, the risks grow exponentially due to the climbers’ impaired cognition and motor skills due to pronounced lack of oxygen. As Thomas said, “To me it was a real shock to see the bodies on Everest, but you know, they were all doing something that they wanted to do, and all trying to tackle the mountain and, unfortunately, this is what we know can happen.”

Thomas began his 8-week journey in Nepal, where he had to acclimatize or adjust to the altitude for a period of time before crossing the Tibetan Plateau to arrive at the north side of Mount Everest from which he would begin his ascent. As Thomas noted, “When I got there and looked at Mount Everest for the first time, I thought it looked impossibly hard and overwhelming and I just couldn’t see any way to get to the top. But when I got to Base Camp One, at the foot of the mountain, I could see the north face going straight up in front of me. I felt feel very sick; I had a constant headache and was very sluggish and tired.”

The sickness that Thomas describes is well-known to mountain climbers as altitude sickness, which causes nausea, fatigue, rapid pulse, confusion, and malaise, along with other symptoms. Continued oxygen deprivation can lead to a fatal swelling of the brain called cerebral edema.

Thomas was clearly suffering from altitude sickness as he made his summit attempt, but managed to reach the top with the help of his climbing partner, Jack Sutcliffe. After reaching the summit, but with the treacherous descent still ahead of him, he was exhibiting signs of cerebral edema. Thomas collapsed and later recounted that at times he had to stop every two steps due to sheer exhaustion, saying “In that situation it really hits you, the how serious Mount Everest is.”

But descending the side of Mount Everest, the vow he had made back in Scotland stayed with him: “The whole point of the Mount Everest expedition was to get the word out about Aberdeen’s Clan charity and the amazing support they give cancer patients and their families. What I was going through on Everest did not compare to the suffering that people with cancer have to go through every day, both mentally and physically.”

With that thought in mind, Thomas made it down off the mountain with the help of friends and strangers. He proved with his successful summiting of Mount Everest, and his own close call on the icy descent, that the hand of a stranger can be a very powerful thing indeed.

Copyright Denis Drabble 2010