In 1972, a small plane containing a Uruguayan rugby team crashed into 12,000 foot mountain in the Andes. The survivors huddled in the wreck for two months before Nando Parado (pictured) and two others made the incredible and improbable journey down the mountain to find help.

We thought we knew what lay ahead, and how dangerous the mountain could be. We had learned that even the mildest storm could kill us if it trapped us in the open. We understood that the heavily corniced snow on the high ridges was unstable, and that the smallest avalanche would whisk us down the mountain like a broom sweeping crumbs. We knew that deep crevasses lay hidden beneath the thin crust of frozen snow, and that rocks the size of television sets often came crashing down from crumbling outcrops high on the mountain.

But we knew nothing about the techniques and strategies of mountaineering, and what we didn't know was enough to kill us.

Experienced mountaineers, in fact, would not have gone anywhere near this mountain without an arsenal of specialized gear, including steel pitons, ice screws, safety lines, and other critical gadgets. They would be in peak physical condition, of course, and they would climb at a time of their own choosing, and carefully plot the safest route to the top. The three of us were climbing in street clothes, with only the crude tools we could fashion out of materials salvaged from the plane. Our bodies were already ravaged from months of exhaustion, starvation, and exposure and our backgrounds had done little to prepare us for the task.

If we had known anything about climbing, we'd have seen we were already doomed. Luckily, we knew nothing, and our ignorance provided our only chance.

Peter Potterfield was ascending Chimney Rock in the North Cascades of Washington when he took a terrible 150 foot plunge, stopped only by a narrow rocky ledge. Trapped, bleeding profusely and badly injured, he struggled to hang on to his life and his sanity while waiting for rescue teams to arrive.

Alone and bleeding, I looked around. The ledge was unnervingly small. Save for the rock face I leaned against there was nothing but airy space in all directions. I sat vertiginously exposed in full sunlight at more than seven thousand feet on the south face of the mountain. The rock and air were heating up fast. I gritted my teeth and concentrated on not passing out.

I let my head fall back against the rock, and realized my helmet had come off in the fall. It must have been toward the end, for I distinctly remembered my head bouncing off the face. The helmet had saved my life. Looking out over the landscape, focusing into the distance, I could make out hardly any detail. Was my vision damaged as well? Then I remembered my sunglasses had gone their separate way in the fall. What about my regular pair? Deep in the top pocket of my pack, in the black crushproof case, were my wire-rim glasses. Intact. Slipping them on was a genuine comfort.

And what there was to see! My view was outrageous, and under normal circumstances the exposure would have been exhilarating. But instead I felt completely removed from normal sorts of responses. The sun was punishing. I couldn't believe what had happened to me. I was marooned, broken, exposed to the elements. I was scared.