| Type | Tube-style belay device |
| Moving parts | None |
| Ropes | One or two strands |
| Difficulty | Beginner (requires instruction) |
From Black Diamond's product name 'Air Traffic Controller', now used generically.
An ATC is a lightweight tube-style belay device. The name comes from Black Diamond’s ‘Air Traffic Controller’ and is now used generically for similar tubes. The rope bends through a slot and against a carabiner to create friction for belaying and rappelling. Simple and versatile, it works with one or two ropes and has no moving parts.
How it works
The rope pinches between the device and a locking carabiner; pulling the brake strand back multiplies friction to hold a fall during belaying.
ATC vs GriGri
Unlike the assisted-braking GriGri, an ATC has no mechanism — lighter and rappel-friendly, but with no assisted lock. See GriGri vs ATC.
Safety
Like any belay device, it only works with a hand on the brake. This article is educational and not a substitute for qualified instruction.
Frequently asked questions
What does ATC stand for?
ATC stands for 'Air Traffic Controller', a belay device made by Black Diamond. The name became so common that climbers now use 'ATC' generically for almost any simple tube-style belay device, regardless of brand.
ATC or GriGri — which should I use?
An ATC is light, cheap, works with two ropes, and is ideal for rappelling and multi-pitch. A GriGri is an assisted-braking device that helps lock the rope, favored for sport climbing and projecting. Many climbers own both and pick based on the day's climbing.
Can you rappel with an ATC?
Yes — a tube-style ATC is one of the most common rappel devices because it feeds both rope strands smoothly. This double-strand capability is a key advantage over some assisted-braking devices that only take a single strand.
Sources
- Belay device technical notice — Petzl