The following is a script from "Taking on the Eiger" which aired on Nov. 29, 2015, and was rebroadcast on June 19, 2016. Anderson Cooper is the correspondent. Tom Anderson, producer.
The Eiger -- in the Swiss Alps -- is one of the most forbidding mountains in the world. Locals call it the Ogre. And for more than a century this monster of a mountain has attracted thrill seekers eager to risk their lives on its nearly vertical slopes. More than 60 climbers have frozen or fallen to their deaths. Now, as we first reported last fall, a new breed of daredevil is taking on the Eiger, not by climbing up the mountain, but by plunging down it. When we heard that after years of planning a new kind of descent was about to be attempted...we went to Switzerland to see firsthand something no one had ever tried before.
At 13,000 feet, the icy summit of the Eiger is too steep and rocky to simply ski down.
[JT Holmes: You ready?]
So JT Holmes is training in three extreme sports to rocket down more of the Eiger than anyone ever has. Right now, he is practicing one of those sports -- speed riding -- on a nearby mountain slope with his friend and cameraman Valentin Delluc.
To speed ride JT is using skis, but also he's attached to a glider-like parachute called a speed wing. It allows him to soar over rocks and ledges impossible to ski.
JT Holmes: You're capable of transitioning in and out of flight at will.
Anderson Cooper: So you're both skiing and then you're flying. And then you're skiing a little bit more.
JT Holmes: Exactly.
But speed riding will only take JT so far down the Eiger. He'll also ski off a cliff and then free fall the rest of the way -- all in one long, non-stop, breathtaking ride.
JT Holmes: Three sports, one run. And they're my three favorite sports. So--
Anderson Cooper: These are the three things you love?
JT Holmes: Yeah. These are three of the things that I love.
JT needs perfect conditions for this dangerous descent, and so far, he hasn't been lucky. Weather on the Eiger is unpredictable.
Fierce winds whip the slopes and change direction dramatically.
JT checks the Eiger every day to see if he can finally head to the summit. The past two years he's had to cancel plans because wind blew the snow off the top of the mountain.
Anderson Cooper: Today, the conditions are not right?
JT Holmes: Well, yeah, today you can't even see the top of the Eiger. So first of all you couldn't land a helicopter up there.
Anderson Cooper: How long have you been planning this?
JT Holmes: You know, the first kinda thoughts of it were upwards of six years ago, but really focused on it for three.
Anderson Cooper: Why has it taken so long?
JT Holmes: You'd be putting your life, you know, in unnecessary risk. So I need the right day.
JT is well aware of the risk. He started out as a professional skier. The steeper the slope, the better.
Now at 35 he makes a living through endorsements and filming his remarkable feats. When we first met him six years ago in Norway, he and his daredevil friends were pioneering the use of wingsuits -- jumping off mountains and flying at more than 100 miles an hour.
But in the last several years, a number of JT's friends and acquaintances have died in wingsuit accidents. Eiliv Ruud who was flying with JT in Norway, was killed in 2012, when he struck a cliff and fell a 1,000 feet.
JT won't be wingsuit flying off the Eiger. The most dangerous part of his descent will be after he finishes speed riding -- when he tries to jettison his skis and freefall down the rest of the mountain. To practice he makes base jumps without skis off a tiny, slippery piece of rock he calls "the mushroom."
JT Holmes: I stepped off the helicopter onto the mushroom and that was fine, I had a good grip. But then I took another step and there was this really thin ice layer. It feels a little more uneven than I remember it.
Anderson Cooper: He's off.
He falls for about 20 seconds, accelerating to 110 miles an hour before opening his parachute.
Anderson Cooper: He's starting right toward us parachute is white, he is red.
Anderson Cooper: That was amazing. How was it?
JT Holmes: Scary.
When JT jumps off the cliff on the Eiger he'll have his skis on, and properly releasing them is critical.
Anderson Cooper: What's the danger if you can't get the skis off?
JT Holmes: You're at risk of an unstable parachute deployment or a snag.
Anderson Cooper: So the biggest danger is that the ski is gonna get tangled up in the parachute?
JT Holmes: That's the risk.
That risk was foremost in his mind because of what happened to his best friend Shane McConkey. In 2007, JT and Shane started skiing off mountains, dropping their skis, and then flying away in wingsuits. It was a dangerous combination they found thrilling.
[Shane McConkey: Oh yeah, another wingsuit ski base. Here we go.]
But on this jump In Italy in 2009, Shane McConkey's ski release mechanism jammed. He couldn't get his skis to come off. He crashed into the ground at high speed, and was killed instantly.
Anderson Cooper: That's how he died. His skis didn't come off?
JT Holmes: He couldn't get his skis off, struggled in his wing suit, and crashed.
When JT is training at the Eiger, he wears a T-shirt with a funny picture of Shane on it. Without his old friend there to help him, he has turned to new friends. Martin Schurmann, is an experienced Swiss mountain guide.
Martin Schurmann: It can change very quickly from good to con-- conditions to-- to really nasty.
Anderson Cooper: It can turn bad very quickly?
Martin Schurmann: Oh yeah. And then you're in trouble.
Anderson Cooper: One wrong step, and you can plunge off--
Martin Schurmann: You're-- you're-- you're gone.
Martin and JT are cautious and methodical, making numerous trips up the Eiger to plan in advance every part of the complex descent....particularly this spot where JT will jump, jettison his skiis, and begin to freefall.
Anderson Cooper: You're standing there on the top of the mountain, what goes through your mind?
JT Holmes: There's two mindsets, you know? There's the Evel Knievel, which is kinda kamikaze, and, "Who knows how it's gonna work out?" and, "Will you hit the landing ramp or not?" And then there's the James Bond. And Bond is composed and dialed. And he uses clever pieces of gear which he developed with Q to, you know, outwit his opponents and pull off tremendous things. And--
Anderson Cooper: Which one are you?
JT Holmes: I'm Bond.
After days of waiting, and years of false starts and cancelled attempts, on this visit in April the weather on the mountain suddenly clears. JT decides the time is right. He and his team take a chopper to the Eiger summit.
JT Holmes: I'm checking for landmarks on the way up and kinda confirming my line, my path of descent.
Anderson Cooper: So you already have a path of descent in your mind?
JT Holmes: It's something that's been, you know, memorized.
The Eiger may be a monster of a mountain, but up close, the summit is shockingly small. Here there is no room for error. No room for the helicopter.
Anderson Cooper: It's not big enough for the helicopter--
JT Holmes: No, it-- it--
Anderson Cooper: --to land?
JT Holmes: It does what we call a tow-in where it just puts its nose into the Eiger. And it just hovers there.
Anderson Cooper: How big is the area that you're standing on at the top?
JT Holmes: The top of the Eiger is pretty small. It's-- the-- there is no flat spot. And there's, you know, workable space is-- you know, three ping-pong tables.
Anderson Cooper: Three ping-pong tables?
JT Holmes: Yeah.
Anderson Cooper: That's it?
JT Holmes: Something like that, yeah.
A mistake here, one wrong step, at 13,000 feet could cost them their lives. JT and his team work for almost an hour.
Wearing crampons on their ski boots they dig trenches with ice axes so they won't fall down the nearly vertical slope. The surface is jagged ice not powdery snow, and it can easily rip the speed wings.
[JT Holmes: I don't like how those things grab the line.]
They file down the sharp pieces of ice so they won't snag the speed wing lines. But the wind kicks up and they have to quickly reposition them. JT decides it's now or never.
JT Holmes: OK, you're good?
Valentin Delluc: Yea.
JT Holmes: Ok...3-2-1 go!
JT launches off the summit. Champion speed rider Valentin Delluc quickly follows, videotaping for us with a camera on his helmet. The ride of a lifetime has begun.
JT Holmes: That's when you turn your skis downhill. Now, doing that, that's very committing. Because, you know, you point your skis down the Eiger, you're probably not gonna stop till the bottom.
Anderson Cooper: One way or the other.
JT Holmes: One way or the other.
JT uses the speed wing for much of the descent, flying over outcroppings of rock and icy slopes too steep to ski.
He reaches an open slope on the Eiger's Western Flank, and lands. He cuts loose his speed wing so it won't slow him down. Now he relies solely on his skis and skill.
JT Holmes: It's black diamond skiing. You're in a really cool place where few people have skied. Really what you're gonna try to do is just gather as much speed as possible and just propel yourself off the cliff.
The cliff he'll ski off is coming up fast. This is the most dangerous part of JT's descent. There is no stopping. He completes a double-back flip to stabilize himself, releases his skis, then freefalls. His nylon suit is aerodynamically designed propelling him forward, so he doesn't crash into any rock ledges. He falls nearly 2,000 feet. Finally, opening his parachute.
JT Holmes: Whoo-hoo...Yea! Yea Buddy. Whoo-hoo. Whoa!
He drifts safely to the ground, landing more than a mile below the Eiger summit.
JT Holmes: Whoa, dude. Whoa. Oh my god, that was pretty intense, man. Nailed it.
Anderson Cooper: Nailed it?
JT Holmes: Nailed it. I don't have words to describe how it felt to go and pull that off after so much time. And, you know, it's kind of a twisted style of having fun. But, it was really fun.
JT Holmes: If you're too fast it's a little just kind of scary...
We assumed JT would call it a day after making it down the Eiger in one piece. But after catching his breath and re-packing his equipment. He decides to head back to the summit, and do the whole run down the mountain once again.
"I don't have words to describe how it felt to go and pull that off after so much time. And, you know, it's kind of a twisted style of having fun. But, it was really fun."
[JT Holmes on summit: 3, 2, 1...go!]
His speed ride off the summit goes perfectly. He flies over trouble spots, and builds up speed as he approaches the cliff edge.
But when he tries to release his skis, one of them won't come off. This is what killed his best friend Shane McConkey. JT struggles for several agonizing seconds...then finally manages to drop the ski.
It's a close call but it doesn't seem to stop him from enjoying the rest of the ride.
Anderson Cooper: Could you give it up?
JT Holmes: I believe that I could. Because I don't feel that I'm-- you know, addicted to this sort of type of thing, this adrenaline, or this sort of high-risk activity.
Anderson Cooper: You're not an adrenaline junkie, you don't think?
JT Holmes: Absolutely not. I prefer adrenaline enthusiast. I truly believe that I don't have to do this. And I truly believe that I enjoy doing this. And--
Anderson Cooper: That's pretty clear.
JT Holmes: The day will come when I tone it down significantly.
Anderson Cooper: But that day is not here yet?
JT Holmes: It's not today.