On October 13, 1972, a chartered twin engine plane carrying an Uruguayan rugby team crash landed high in the Andes mountains. How they survived has inspired both admiration and horror.

As the plane encountered its first signs of trouble, none of the passengers panicked. Few even showed much alarm. Most of the 45 on board were in their late teens and early 20s, members of a team traveling to play an exhibition in Chile, and they whooped and hollered when their chartered plane hit turbulence over the Andes and dropped several hundred feet. Then the plane hit a second air pocket, and dropped some more—and now, suddenly, as it fell beneath the cloud cover, the passengers could see a mountain face just 10 or 20 feet away.

“Is it normal to fly so close?” one of them, Panchito Abal, asked his friend Nando Parrado.

“I don’t think so,” Parrado replied. Then his world went black.

When he awoke, almost 48 hours had passed. It was Friday, October 13, 1972, and the Uruguayan Air Force Fairchild F-227 had crashed into a glacial valley high in the Andes. The tail was missing—cut away from the rest of the fuselage by the right wing, which had sheared off after hitting the mountainside.

Seven of those on board had been sucked out of the fuselage before the plane had crashed; four more, including the pilot and Parrado’s mother, were killed upon impact; and by the time Parrado regained consciousness, a further five had also perished—including the co-pilot and Parrado’s friend Abal.

There were now 29 survivors, alone in the bitter cold of the Andes, with no way of contacting the outside world and their plane’s white fuselage all but invisible in the snow to any would-be rescuers that passed overhead. By the time their ordeal ended, an almost unfathomable 72 days after it began, the total number of survivors had dwindled to 16.

It later emerged that those who survived had done so in part by eating their fallen dead comrades. While world reaction was initially one of revulsion, that soon gave way to an appreciation of the fortitude and inventiveness that enabled them to beat seemingly impossible odds. The harrowing experience became known as the “Miracle of the Andes.”

Those with the strength and awareness to do so immediately began tending to the more seriously wounded. They piled up airplane seats to create shelter in the broken fuselage, where they huddled day and night. They used aluminum from the seat backs to warm up snow and provide a steady stream of drinking water. But their rations were woefully inadequate.

One morning, Parrado later wrote, he found himself cradling a single chocolate-covered peanut: “On the first day, I slowly sucked the chocolate off the peanut … On the second day … I sucked gently on the peanut for hours, allowing myself only a tiny nibble now and then. I did the same on the third day, and when I finally nibbled the peanut down to nothing, there was no food left at all.”

In the high altitude of the Andes, it was a matter of time before their bodies consumed themselves completely. They had only one choice. Using a shard of glass, some of the survivors sliced thin slices from the buttocks of one of the corpses, and silently, they began to eat.

Some resisted taking that fateful step for as long as they could, clinging to hope that they would be rescued. But then they found a transistor radio and a small group listened intently as a Chilean news bulletin announced that official search efforts had ended.

“Hey boys!” one of them shouted to the rest of the survivors. “There’s good news. They’ve called off the search.”

“Why the hell is that good news?” yelled one in response.

“Because it means we’re going to get out of here on our own.”

On the 18th day, disaster struck. An avalanche all but buried the fuselage, killing another eight, and strengthening the conviction of those remaining that they now had to strike out across the mountains in search of civilization and rescue. It seemed an impossible task: None of them were mountaineers. All were horribly weak. And they had no suitable clothing or equipment. But there was no alternative. They fashioned a sled, sewed together material for a sleeping bag and selected those who would make the march.

After weeks of preparation and aborted efforts, the group—initially three, but then two, to save resources—set off to the west, in the direction of Chile. Fighting cold and crippling altitude sickness, they somehow ascended the nearest peak, all 15,000 feet of it, and surveyed the surroundings. They saw little but more mountains and a valley that wound through them. “We have been through so much,” one of the climbers, Roberto Canessa, said to Parrado, the other. “Now, let’s go die together.”

Desperately, uncertainly, they picked their way down the other side of the mountain and began to stumble along the glacier down below, trying to force themselves onward but weakening day by day until, on December 18, they heard rushing water. It was the mouth of a river, which they began to follow. The next day they saw signs of humanity: a rusted soup can, a horseshoe, cow dung, a herd of cows and then, finally, on the evening of December 20, a man on horseback on the other side of the river.

The following day, they were greeted by three more, and Parrado, unable to make himself heard above the roar of the river, tried to explain who he was by miming an airplane crashing. Even as he did so, he worried the men would think he was a lunatic and leave.

Instead, one of the men tied a note to a rock and threw it across the river: “Tell me what you want.” Parrado, his hands shaking, began writing: “I come from a plane that fell into the mountains.” He explained that he and Canessa were weak and starving, that 14 friends remained on the plane, and that they needed help desperately soon.

“When are you going to come fetch us? Please. We can’t even walk. Where are we?” As he was about to throw the rock back, he paused. Was he even strong enough? He summoned up the last of his strength and hurled the rock with all his remaining might and watched as it bounced on the river’s edge and rolled onto the bank. The man read it and raised his hands as if to say, “I understand.”

Later that morning, another man appeared on horseback, this time on their side of the river, and soon they were in a hut, being fed hot food. The Chilean mounted police arrived, and a pack of reporters. Rescue helicopters landed, and while their crews clearly doubted Parrado’s story of scaling and descending the mountain, they set off with him in search of the plane.

Violent turbulence battered and shook the helicopters, which screamed as they attempted to climb the mountain; as soon as they passed over the peak, fierce winds drove them back, forcing them to fly around the mountain and approach from the south, disorienting Parrado, who was filled with fear that he would not be able to find his comrades. Then, suddenly, he saw black specks on the ice; the two helicopters touched down, rotors still running, and took six survivors, disgorging a rescue team to take care of the remainder overnight until their ordeal, too, could finally be ended the following morning.

At a hospital in San Fernando, Chile, Parrado was relieved of his layers of filthy clothing and given a warm shower. As he was being toweled dry, he caught a glimpse of himself in a mirror. He was skin and bones, a shadow of the athletic young man he had been when he boarded the plane two and a half months previously. But, with each breath he took, he uttered two words to himself, over and over.

“I’m alive. I’m alive. I’m alive.”