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Accident Analysis: Shunt Pops Off Rope While Toprope-Soloing

Is toprope-soloing safe—and how can we make it safer?

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The Accident

On September 19, 2021, the 41-year-old climber Craig Faulhaber was solo-toproping the route Burning Down the Haus, a short (five-bolt), gently overhanging 5.13d on the massive boulder of Haus Rock in the high country near Keystone, Colorado. Faulhaber teaches math at Arapahoe Community College in the Front Range of Colorado and shares his van with his girlfriend, Jackie; both are dedicated climbers who are fixtures on Colorado’s Front Range and also volunteer their time updating hardware—and in fact had done so with the anchors at Haus Rock in summer 2020 as the rock saw increased traffic during the pandemic.

That day, Faulhaber was working the top crux of Burning Down the Haus, which features a 10-foot stretch of V8 crimping about 30 feet off the ground; he’d rappelled in to work only that section, fixing a 9.5 mm dynamic line to the anchor at the lip of the wall.

Faulhaber had gotten more into solo-toproping during the pandemic, when partners were hard to find, and continued to use it selectively on projects. As Faulhaber posted on Mountain Project, he was attached to the rope using a Petzl Shunt, a device designed to be used as a rappel back-up. The Shunt was clipped to his belay loop with an anti-crossloading locking carabiner, and Faulhaber also had backup knots—overhands on a bight—in the rope below, in case the device’s cam somehow failed to engage. The rope was weighted, says Faulhaber, with a couple of filled water bottles plus shoes, and coiled above the ground. (When solo-toproping, it’s common to weight the rope to make it easier for your device to slide—so you don’t have to stop to reel in slack, especially low on the climb.)

He’d previously tried this section self-belaying with a Grigri, which would give him the option to lower back down and work moves, but wasn’t able to pull slack through, causing a loop to build up. So Faulhaber had opted for the Shunt, whose cam you can disengage in order to lower short distances and re-work moves. He’d learned about the technique via a blog/YouTube video posted by a UK-based professional climber, who’s since removed the video. Faulhaber had bought the Shunt online, and the Technical Notice for the device at the site where he purchased it showed solo-toproping on a fixed line as an approved use. (In 2012, Petzl updated the Technical Notice, removing self-belaying as an approved use; they note that, in earlier Technical Notices, they’d also “warned against possible ways to defeat the device while self-belaying.”)

Before getting on Burning Down the Haus, Faulhaber had experimented with the Shunt on easier terrain and felt good about it. “It is an extremely simple device, so easy to set up and understand,” he says. “It didn’t seem possible that a rope could come out, which was my only major concern—a stopper knot below would handle any issues with slippage.”

That day, wrote Faulhaber in the Mountain Project post, “I try the section, fall on the Shunt, brush, lower, try again, repeat.” (Faulhaber estimates he’d hung or fallen on the Shunt dozens of times that day, and had used it two previous days on the route.) “I actually finally got the sequence and was pretty happy, looked down at a fellow climber who was watching to express some psych, and decided to try one more time.”

This time, Faulhaber fell. Then something went terribly wrong and he plummeted to the deck—a flat staging area that consists of hardpacked soil and rocks. Climbers on the ground called 911, and the Summit County Rescue Group quickly arrived to evacuate Faulhaber, who was still conscious, to the Keystone Medical Center. (“I responded every time a rescue worker asked me how I was doing, even as my blood pressure tanked,” he wrote on his blog.) From there, he was evacuated via the Flight for Life helicopter to St. Anthony’s Hospital in Denver. Faulhaber had 12 broken bones, including fractures to his L1 and L2 vertebrae, both heels, his right elbow, pelvis, sacrum, and ribs. As Faulhaber recovers at a residence hotel (vans not being great places to convalesce), he has slowly begun walking and climbing again.

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What Went Wrong?

Like all genres of climbing, solo-toproping is not without risk. You can rig the device incorrectly, the device can get crossloaded and fail, or your rope can saw over an edge and fray or break when weighted. Foresight, vigilance, and planning can help avoid these scenarios, but solo-toproping will never be 100-percent safe. Things can change in an instant: Your device can flip, perhaps as you rub against the rock; your rope protector might no longer be in the ideal spot over an edge as your rope changes vector; or you might fail to reel in slack quickly enough, as can happen low on a climb, building up a loop that creates a large fall—and shock-loads your device. Compounding these issues is the fact that climbers often use devices that aren’t expressly designed for solo-toproping.

Climbers have been using the Shunt—today labeled by Petzl as a “Rappel backup device for sports activities”—for solo-toproping since the 1980s. It had always, however, been understood that you do so only on vertical or slabby terrain, where the rope hangs straight down next to the rock—otherwise, on overhanging terrain, you risk a longer fall in which the Shunt slides down the rope before it engages, as well as possible device failure from shock-loading. In Faulhaber’s case, the section he was trying was about 5–10 degrees past vertical, with one draw clipped above him before the anchor to keep the rope close to the rock.

So what happened? In this case, Faulhaber hit the ground with the Shunt and locking carabiner still attached to his harness: The Shunt had come cleanly off the rope, and showed minimal deformation upon later inspection by a fellow-climber. And the rope was intact, too, with its stopper knots still tied.

A Possible Mechanism of Failure—and Another Accident

In this video, the mountain guide Yann Camus of Bliss Climbing looks at one way in which the Shunt can detach from the rope. In what he calls the “Scorpion Catch,” the device essentially inverts on the carabiner—pushed out of place by rubbing against a protrusion on the rock or other piece of gear. And then, when the inverted Shunt is suddenly weighted, as in a fall, the rope pops out of its channel and exits the device.

Faulhaber surmises that the gymnastic positions on the V8 crux, including a big highstep, somehow set up the Shunt for failure. But he isn’t sure precisely how. Fortunately, there were witnesses to the accident, one of whom inspected the Shunt and reattached it to the rope to see what might have gone wrong.

(1) The Petzl Shunt that Faulhaber was using on Burning Down the Haus, showing one possible, less-than-ideal angle of loading that could have caused the rope to pop out of the device. (Photo: Adam Levine)

One theory which emerged was that the Shunt was loaded at a strange angle that flexed its C-curvature, letting the rope pop out (see Photo 1). The second, perhaps more plausible theory, dovetails more with Camus’s Scorpion Catch: Wrote Faulhaber on a Mountain Project thread, “The device may have been loaded when the rope caught in it similarly to the second picture (instead of the typical Shunt fall where the carabiner loads the camming device first). This could snag immediately, creating some large and odd forces, causing the device to open. The important point here is that if the rope snagged, the time it took to load my weight onto the device could be dramatically reduced versus a typical Shunt fall, thus increasing the forces” (see photo 2).

“I’d say that the Shunt probably turned sideways just below my waist as I highstepped with my right foot and moved my left foot in below it,” says Faulhaber. “Maybe some rubbing created just enough friction to put a small amount of slack above the device to allow the rope to catch as I fell. Once the rope caught, the Shunt flipped the rest of the way over into the ‘Scorpion’ configuration”—at which point the rope popped out of the device.

(2) The same Shunt, showing the most likely position it was in prior to the rope escaping the device. In this scenario, the sideways Shunt could have inverted into the “Scorpion” position proposed by Yann Camus, a position that’s alarmingly stable—and predisposes the rope to popping out of the device. (Photo: Adam Levine)

Sadly, even as Faulhaber has worked to put the word out about his accident through his blog, the Mountain Project, and an interview on the Clipping Chains podcast, there was another, similar accident.

On November 30, 2021, an experienced climber of 10 years, Trevor Stuart, was using a Shunt to solo-toprope the upper dihedral of The Greatest Show on Earth (5.13a) at the Lower Meadow, New River Gorge, when something went wrong. (Stuart had been solo-toproping for three-plus years, and using the Shunt to do so for at least a year after seeing the method in the pro climber’s YouTube video.) He climbed on a single 9.5 mm dynamic line, weighted at the bottom with his approach shoes and cams, and had no back-up device. Wrote Stuart’s sister, Chelsea Bond Stuart, in an email: “[Trevor] knows how he set it up, but has no memory of falling. We’re told by the climbers who found him that he likely fell around 60 feet. His injuries include a laceration to his right arm and kidney. Broken bones to the thoracic and cervical spine. A subdural hematoma. Five broken ribs.”

Nate Snydor was one of the first climbers to respond to the accident, and along with others helped stabilize Stuart while they waited for first responders to arrive. Snydor’s friend Louis Aden then went up to the cliff top to take down Stuart’s anchor, finding what Snydor calls a “super-pro” setup. But one detail stuck with Snydor—who confirms that the Shunt and locking carabiner were still clipped to Stuart’s belay loop down on the ground, as had happened with Faulhaber: The rope below where Stuart was climbing was in a rat’s nest, and not a neat coil, as you typically do when solo-toproping, as the coiled rope adds weight to the system that helps your device slide. “He had what looked like a clove hitch around the level of the roof, with tennis shoes and a couple other things clipped to it. This signaled to me that he had rappelled in, setting directionals, gotten to the lip of the roof where it’s no longer reasonable to TR solo, tied off his gear, changed his shoes, and proceeded to climb. With a system as dialed as his, why the huge rat’s nest of rope?” wrote Snydor in an email. “My assertion is that he likely had his rope coiled at the bottom of his setup, similar to pretty much every one, including myself, when we TR solo. I honestly think he had a neat coil, and when he fell on the pitch and the Shunt detached, he grabbed the coil as he plummeted by, or got snaggled in it, saving his life in the process. I think if he had freefallen from the height of the crux, we would have come upon a really nasty body recovery instead of what ended up being a miracle survival.”

After a one-week stay in the ICU, Stuart is back to walking and will be seeing specialists for his injuries as he focuses on his recovery.

In any case, no matter what the mechanisms of failure were in these incidents, Faulhaber would like to stress that climbers stop solo-toproping with the Shunt before another accident happens. And Petzl, for its parts, adds that “There are a wide range of factors which could be the cause of these reported falls” and stresses that climbing with a partner always remains the best solution—and, of course, to stop using the Shunt for toprope self-belay.


There are a few basic laws of solo-toproping you should follow in order to stay as safe as possible:

  • Do NOT use the Petzl Shunt for solo-toproping. While an earlier Technical Notice dated prior to 2012 for the Shunt showed “Self belaying” as an approved use, as long as you avoided overhanging terrain and followed other express warnings, the most recent technical notice (2012–present) at does not. In the wake of these accidents, Petzl has reiterated that the Shunt must not be used for self-belaying, as published in a December 2021 Instagram post. Per the manufacturer’s current Technical Notice: “The Shunt is personal protective equipment (PPE) used for fall protection. It is only to be used as a rappel backup device for sports activities. This product must not be pushed beyond its limits, nor be used for any purpose other than that for which it is designed.”
  • ALWAYS use a static rope when solo-toproping: Dynamic ropes introduce stretch and hence longer fall potential, introducing greater forces and greater opportunity for device failure. They are also not as resistant to damage from the rope-gripping teeth on some devices, nor to abrasion over edges.
  • Whatever your solo-toproping setup of choice, ALWAYS have a second, back-up device. If you are relying on one device and that device fails, you risk serious injury or death. (Petzl recommends that you always use a redundant system with two devices per the technical information found on the Petzl technical-tips section of their website.)
  • Tie stopper knots in the rope to back up your devices.
  • Use rope protectors, directionals, and conscious rope management to protect your cord while you climb.
  • Double- and triple-check your set-up, both on the ground and while you climb. Make sure your devices remain oriented correctly and are not cross-loaded.

Further Resources from Petzl

Finally, for all of those who do pursue roped solo climbing, Petzl has compiled a series of tech tips on the subject:



Matt Samet is the editor of Climbing Magazine.

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