Air Traffic Controller (ATC) In Rock Climbing

Every sport has its own acronyms and part of learning the sport is learning those acronyms. For climbing, a common one is ATC climbing. Many people even think the name is a joke when they first hear it, it doesn’t sound like a climbing term, but it is.

In this article, we’ll define and explain what an ATC is, why you need one, and the different uses, functions, benefits, and drawbacks.

What does ATC Climbing Stand For?

In climbing, ATC stands for “Air Traffic Controller.” Not to be confused with the people responsible for flights landing and taking off in a coordinated fashion, the ATC in climbing is a very common belay device.

ATC’s were developed by Black Diamond. The Air traffic controller belay device is tube-like in shape. An aluminum ring is split down the middle and divided into two different loops. One side is then attached to a plastic loop.

The Black Diamond ATC was so popular after its invention that many companies went on to copy the product, but the name stuck and so now any of these belay devices, regardless of company, is referred to as an ATC.

Types of ATC Devices

There are three different types of ATC belay devices. The basic, the XP, and the guide device. Each has something unique and a benefit to go along with it and we’ll discuss each in the following paragraphs.

Basic ATC

Black Diamond ATC

The basic ATC is pretty much the same as it was since Black Diamond invented it. The top section is made up of an aluminum ring, somewhat oval in shape, divided down the middle into two halves. On one side of the device, a plastic loop is attached.

To use an ATC, the belay side of the rope is fed through one side of the device in a loop shape. A locking carabiner is then set through both the plastic loop and the rope.

This simple piece of equipment is one of the cheapest but most important parts of your gear.


Black Diamond ATC XP

The ATC-XP is a more aggressive version of the traditional ATC model. It has teeth on the opposite side of the plastic loop. These teeth create more friction with the rope as it passes through them.

The XP is designed mostly for ice climbers and situations where the rope may become wet. The teeth provide extra bite and can help stop a fall even when a rope is soaked.

ATC Guide Device

Black Diamond ATC Guide Device

Finally, the ATC guide device is the most complicated but versatile of the three types of ATCs.
Opposite of the teeth you’ll find a metal loop added to the device. This loop serves two purposes.

The first benefit of this style of ATC is that it allows a climber to belay their partner from above. This can be especially helpful on big wall climbs with multiple pitches. The lead climber becomes the belayer using this setup.

You can also set up the guide so that it has automatic locking functions. The loop on the ATC can be attached to an anchor point with a locking carabineer, creating a stopping point and an additional piece of protection for the climb.

Using an ATC Device for Belaying

Using an ATC device for belaying is pretty simple, but it’s critical that it’s done right to ensure the safety of the climber! Here is a quick summary of the steps, followed by a video to illustrate the points!

  1. Make a small loop from the belay side of the rope.
  2. Feed this loop through one of the sides of the ATC device. You’ll want the rope loop and the plastic loop that is attached to the device on the same side. Many ATC devices have a little graphic showing where the rope ends should go.
  3. Grab a locking carabineer and use it to grab both the plastic loop and the rope loop.
  4. Attach the carabineer to your climbing harness’s belay loop.
  5. The climbing rope is the top one, and is attached to the anchor. The brake rope is on the bottom and should face away from the climber.
  6. Your ATC device is set up! You still need to make sure to follow proper belaying techniques for the safety of the climber. If you haven’t gone through a belaying training course, we highly recommend it.

Using an ATC Device for Rappelling

If you would like to rappel using an ATC device you’ll want to make sure that you have the ATC guide device style unit. The first step is the set up your anchor and attach it to the metal loop opposite the teeth of the device.

Then, steps one through 5 from the “Using an ATC Device for Belaying” can be repeated.

Now, when you are repelling you can use the brake side of the rope to stop yourself at any point by pulling down and putting pressure on the device. By ‘giving’ a little slack to that rope you will start to lower down. the less pressure on the brake rope, the faster you’ll go.

Benefits and Drawbacks of an ATC Device

There are several different types of belay devices common to the rock climbing world so it’s important to know the situations when an ATC is a good option and the drawbacks of it that may lead you to use one of the other devices on the market.


  1. The ATC is the cheapest and most simple belay device used in climbing
  2. Most other devices are based on the ATC techniques, so learning it will have carryover for all belay devices.
  3. Very versatile, many climbers use it in combination with other devices.
  4. Simple design and very lightweight
  5. Can be used for both belaying and rappelling


  1. The main drawback is the lack of an auto-lock feature. The belayer must be on alert at all times. Any mistake by the belayer could lead to injury for the climber.
  2. Belaying using an ATC is a more manual task than other devices and can be tiring.

The Final Pitch

As you can see, the ATC is a versatile device for rock climbing. The ATC can be used for both belaying and rappelling and is the cheapest of the different types of belay devices on the market. Learning how to use the ATC can help you in your climbing whether it be sport, trad, ice, or big wall.

When properly used the ATC is a safe option for belaying, but make sure you are educated on proper belaying techniques!

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Our writer/editor and youngest team member, Nick is in school for journalism with a minor in climbing. Just kidding. There is no minor for climbing. We wish though!

Nick has the benefit of being fairly new to the world of climbing, and thus is able to look at our content and make sure we explain things in a way both experts and people who have never put foot on a wall will understand!