Successful Sending


It’s a gorgeous day despite the oppressive heat of the 2014 summer. I shade my eyes as I smack the cable three times, telling my co-guide that he is clear to send our next guest down the zip line. With only one zip to go on the afternoon tour, we’re in the home stretch after a long day. 

A participant appears from between the trees, hand hovering over the cable waiting for my signal. Unfortunately, they don’t make it to the platform and, in a fit of nerves, they let go completely and slide out into the middle of the zip, coming to a rest in the belly.

I grab my radio and call out the all-stop command: “Do not send. Do not send. Lead to Sweep, do not send. Do you copy?”

I wait for the copy as I reassure the guest sitting mid-line. I am unnerved when my call is met with silence. I double check the channel, turn up my volume in case I missed the response, and try again.

Still nothing. So far on this tour, my experienced co-guide and I have managed to communicate effectively with each other. I reassure myself that he will follow the trained protocols—no “zip is clear” communication, no sending.

My attention is split between wondering if the transmission went through and attempting to retrieve the stuck guest. I ask if they can pull themselves in but know the answer even as they shake their head at me. Totally fine, this is what we trained for. I tie a prusik and begin to attach myself to the line.

In that moment I hear the tell-tale whine of the cable, faint at first but rapidly gaining intensity. I look up in horror as another participant appears from between the trees. 

Training kicks in and I start to yell, “BRAKE!” while waving my arms in an exaggerated braking signal. The second participant slows themself enough that the midair collision is gentle, but clearly unnerving. 

Desperate to stop this situation from escalating any further, I yell the do-not-send sequence into my radio again. I repeat myself twice, loudly and in rapid succession, hoping that my co-guide hears me.

I grab the rescue bag and, as I begin my descent, the guests begin truly panicking—shouting and waving their arms towards the sending platform. Dread curls in my gut as I hear the whine of the cable begin again…

It’s been nearly 10 years, but the memory of that day lives on. I feel the same sense of horror every time I revisit that tour in my mind. It is a nightmare that, despite advancements in technology and practices, staff and guests still experience today.

I consider myself lucky—no one was injured beyond bumps and bruises. Not all situations end this way, however, and each year, the industry experiences mid-air collisions and multiple-participant incidents on zip lines. So, what can we do better?


It’s important to examine what works for your park when it comes to establishing effective zip line operator communications. Current industry practices for indicating a “clear zip line” include use of radios, specific verbiage or phrases, “buddy” checks with other staff members, visual cues, and cable tapping. 

While some operations use just one of these methods, success is most often found when a combination of signals and cues come together to indicate that, without a doubt, it’s safe to send another participant. To set staff and guests up for success, let’s break down these various factors.

Visual cues. If you have an unobstructed line of sight, visual cues, such as hand signals, flags, or the status of the braking system, can help to indicate a clear zip. However, if there is not a clear line of sight, or there are conditions that regularly disrupt the line of sight (wind blowing branches; looking into the sun), it’s important to understand that the sending guide is effectively flying blind. Their ability to verify a clear corridor will be limited, and redundancies must be in place to prevent miscommunication.

The North Carolina-based U.S. National Whitewater Center (US NWC), which offers 1,300 acres of recreation, has found success in an “all clear” flag system on its zip lines. 

Outdoor activities assistant manager Allison Leedom says the flags are helpful and easy to use correctly: for one, a guide must actively pull on a bungee system to raise a flag into the “clear” position and flags automatically return to the “not clear” position when a guide releases the pull. This visual signal is also worked into the guest briefing on the sending side, says Leedom, when, after checking the participant’s gear, the guide will ask the participant if they see the flag—this creates a double check. 

Other operations have guides use hand signals. Sarah Brubaker, the aerial sports program specialist for the Summit Bechtel Reserve, a West Virginia-based training, scouting, and adventure center, says she created distinct hand signals that were visible from afar to communicate with guests about when to brake on a hand-braking course, as well as hand signals to use when all other communications fail to indicate a “do not send.”

Devices like the C-Pass Zip block zip line access if a rider is on the line.

Auditory cues. Many operators communicate with technology such as radios when clearing zip lines. Radios can be an incredible tool when used correctly and can simplify an otherwise complicated process. 

When shopping for radios, operators should consider reliability, weather resiliency, and range. Conversations with other parks can be extremely helpful and, as always, a brief internet search can also provide plenty of reviews and information. If new radios aren’t in your budget, some manufacturers and vendors offer rental options. 

Technology. Beyond radios, the industry has seen a surge in new technology specifically designed to address issues with zip line collisions. 

Kanepeo created the zipEYE system for the Saferoller continuous belay device. The zipEYE is a gated communication device in which a cable gate locks once a participant passes through the sending end and does not unlock until the participant has passed through the receiving end. It includes a control box that can communicate if a participant hasn’t left the corridor in the pre-programmed time period. 

CLiC-iT offers the C-Pass Zip, an access control system that blocks zip line access if someone is already engaged. The system has different models to work with CLiC-iT or Kong Zaza 2 devices and communicates using RF wireless technology. A remote-control option allows operators to monitor the status of the in-box. 

Finally, Skyline Ziplines debuted its Safe Launch System, which utilizes an electronic launch mechanism and magnetic gates for zip lines that do not allow the operator to send a participant until the required safety checks are confirmed, landing decks cleared, and the catch block reset. 

There is no doubt we will see more advances in this area in the coming years. 


One of the most important things to consider when evaluating zip line communications is that what feels like the exception is often the rule: if a command or signal can be misunderstood, at some point, it will be. 

This is where clear, concise, and redundant communication comes in. Having two methods to indicate a clear zip, or having a double-check included in the protocols, can counteract the potential for crossed wires. 

For verbal commands, most operations utilize specific scripts to bake-in double checks and redundancy while also creating a sense of excitement and trust for guests. “It’s drawn out, but it’s exciting for participants to hear, almost like a rocket launch,” says Brubaker. “They get into it.”

A script also conveys to guests a sense of professionalism, Brubaker adds, because it sounds the same every time. And the key to zip line communication lies in its consistency. “We make sure the language is clear, concise, and the same every time,” says Brubaker.

A longer script allows guides the opportunity to identify that each piece of the system is in place and ready to receive: At the Summit, says Brubaker, receiving staff state in their radio calls not only that the zip is clear, but which lines specifically are in use as well as the status of the braking systems (e.g., Landing to launch: brakes are set.). 

Staff on the zip line recieving platform communicate via radio at Quarry Park Adventures, Calif.

All-stop scripts. Scripts are also important in communicating an all stop. If a staff member must perform a rescue, for example, it is crucial that they know what to say in that stress-filled moment. Leedom says that US NWC trains and uses specific verbiage during interventions, not only for clear communication, but also because you don’t know who is listening and what they may hear. 

All-stop communication should sound vastly different from “clear to zip” communication. Using the same words in radio calls (i.e., zip is clear, zip is not clear) can cause issues, as staff may make assumptions if only part of the message is heard. 

Trainees at the Summit are taught to ask for repetition during radio calls. “We teach that if you don’t understand, you ask for repetition,” says Brubaker. “It can be intimidating for new guides to ask a seasoned professional on the other end. We always make sure they know that it is OK to ask for clarification.”

At many operations, receiving staff are required to copy the call indicating they heard the message and understood.

Visual miscommunication is possible as well. Leedom says the US NWC is specific with staff about what they can and cannot wear. “We say no bright colors on the landing decks, especially orange. We don’t want someone moving around and being mistaken for an ‘all clear’ flag.” 


While we certainly cannot plan for every potential calamity, we also need to recognize that things do go sideways. This is where having an understood “Plan B” for your staff comes in handy. 

The best way to prevent an issue is to identify conditions that may cause the problem in the first place.

Technology is a wonderful thing right up until we rely on it fully and it ceases to function. If your technology requires charging, for example, a protocol should be in place for ensuring equipment gets charged regularly. The Summit also sends staff out with extra radios on the more difficult-to-access canopy tours to circumvent issues with battery life. 

Creating, informing, and training staff on a backup plan is key, especially if they are going to struggle or be unable to access other forms of support. When visibility is low, Leedom equips her staff with radios to use instead of flags. 

While cell phones can be extremely helpful, in remote situations, depending on the provider and the location, service may be nonexistent. Staff may also be expected to leave their cell phones behind or may choose to leave them to avoid losing or damaging the device. So, it’s important not to rely on personal cell phones as your only backup.


Minimizing mistakes means examining and learning from past incidents and near-misses.

Both Brubaker and Leedom have had experiences with midair collisions at previous employers, and both were disappointed when previous managers did not address the incident with the entire staff. 

“There were definitely repercussions for the person responsible, but it wasn’t enough of a culture shift for the rest of staff,” Brubaker says. 

Leedom was similarly disappointed when, after a guest was sent without a “zip clear,” nearly resulting in disaster, leadership at the operation spoke to the sending guide and then swept it under the rug. 

Both agree the only way to prevent incidents like these from happening again is to inform staff and have conversations around the importance of following protocols. At the US NWC, Leedom says that when a near-miss occurs, a field report is filled out to keep track and build accountability into the systems for all staff. 

“If you make a mistake, we’re going to talk about it because someone else might make the same mistake,” she says. 


We all want to keep people safe—that’s a common thread throughout our industry. Zip line operation communications is an area of grave importance, and understanding that should spur us to improve our protocols and practices. 

The world of zip lines is vast and varied. Strategies that work for others may not be ideal for your operations, and vice versa. Always be sure to do your homework and consult the appropriate authorities before making drastic changes to your protocols.


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