"You are eating a dead person and the person is your friend and you wonder, 'Should I do this? Or should I let myself die?" he says. "But I have seen how mothers cry when they lose their sons and I didn't want my mother to go through that. I realized that when you have a reason for doing something, nothing stops you."

The movie focuses on what Bayona refers to as the "generosity" of the act rather than exploiting it for shock value. "This is a horrible story that is never focused on the horror," he told the BBC. "The way we approach the story is quite the opposite. It's focused on the human aspect of the story and on the friendship, on the extreme generosity they had to each other."

The group experienced another calamity as they patiently awaited the arrival of spring to witness the snow melting. On October 29, their misfortune intensified when two consecutive avalanches engulfed the fuselage in snow, resulting in the tragic demise of eight individuals and leaving the remaining survivors trapped inside for a harrowing three days. Those who managed to survive were compelled to depend on the deceased bodies entombed with them for sustenance.

"We tried to keep our sense of humor," Canessa says of the days they were snowed in by the avalanche. "Sense of humor is very important in life. It's important to laugh at your own condition. That makes you keep going. So if you had something nice to say you would say it and if you had something sad to say you would keep it to yourself. We always worked together to try to raise spirits."