Transcript for French Daredevils Push Limits Sky-High
Most of us will never get to go on a spectacular journey that we're going to take you tonight. People who turn hand springs as they look down on the clouds. How exactly do they do it and why. We chased them around the alps to find out. Staring down danger is a way of life for these men. They're always pushing themselves and each other to go farther and higher. . Reporter: The idea that you appreciate life more when you court your biggest fears is something that I'm having trouble getting onboard with. Keep moving. Keep moving. I'm try popping. You see, I am terrified of heights. Look down into the valley. Embrace your fears. I can't. And when we were invited to go to the summit of chamonoix to watch them train, my nerves are already getting the best of me. Oh, boy. So when we get to the top, I glue myself to the only place that seems safe. I feel like a little school kid. I'm just going to sit here and wait. But he decides to take me on as a project. Sometimes I have the same feeling. I'm really, really scared but I know if I overcome this fear, I feel like I'm floating on the clouds. Reporter: How do you get to that point? By pushing myself. Reporter: I don't know if I'm that brave. Clearly not the case for these flying frenchies. Today for fun, they will throw themselves off the mountain and attempt to cross in midair. It's like driving a car. You can have an accident anytime if you're not focused. Reporter: Good luck. Thank you. Reporter: That's okay. You guys just leave me. They believe they're pulled to the edge by an instinct so basic it's from when humans were predators, hunters. The need to find their own food. And they will have an adrenaline rush. You need to be calm, quiet, no noise and then there are people like me. Reporter: These rugged alps have become their playground, but they've also learned some hard lessons about their own limitations. People used to say to me Yo start to feel powerful. I was doing the action without feeling the fear anymore and the danger. The fear always has to be there. Because if you're not scared anymore, it means you don't feel the danger and you will have an accident. Reporter: Distracted while filming his friend during the stunt, tancred lost focus. I followed my friend when he was opening his parachute, I wept B on my back. I turned around and I realized I was too low already. I opened my parachute and I hit the ground. Tancred broke some bones and not long afterwards, his friend broke his back. Humbled and wisened from this experiencejust four months later, they are pushing the boundaries of human capacity once again. One stunt is a second in the life. But the whole process is days maybe months. So if you don't enjoy the journey, you miss most of the joy. They will attempt to cross from one peak to the other on a one-inch wide piece of nylon. Understand you are on the line, you just enjoy the crossing. One of top sky divers in the world, Julian is able to do much more than cross. But since becoming a father, his taste for tempting fate has diminished. Now he wears a security leash. I say okay, maybe I want to do it solo, but is it worth it. Try iing a solo flight untethered. You need to stay focused all the time. While on the line, he takes on a trance-like state. Sometimes it's like you lose reality. You are getting outside your body and looking at yourself from a point and suddenly you realize oh, my god, what am I doing here? Reporter: The experience overwhelms him and he falters. Then purposefully, he falls to give himself a moment to calm down. It's a situation he has prepared for. He gets back on the wire a then this is what they mean by facing your fears. He knew the risk, he had a plan and that's what saved him and enabled him to go on. For "Nightline" in chamonix, France. Amazing. If you think that was frighten, join us tomorrow night for this
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