How Arborists Climb Trees Safely (Behind the Scenes)

When most people watch an arborist work, they see someone scaling a massive tree with ropes and a chainsaw, and they think one of two things: "That looks terrifying" or "That looks like fun." The reality is somewhere in between, but what most people do not see is the amount of planning, training, and specialized equipment that goes into making tree climbing look routine.

Here is a behind-the-scenes look at how professional arborists get into trees safely, what gear they use, and why it matters when you are choosing someone to work on your trees.

The Gear: More Than Ropes and a Harness

A climbing arborist's kit is extensive. Here is what a typical setup includes:

Saddle (Climbing Harness)

Tree climbing saddles are specifically designed for arboriculture. Unlike rock climbing harnesses, they are built for extended work positioning, meaning an arborist can hang comfortably in one spot for hours while pruning or rigging. Modern saddles have wide leg loops, gear loops for attaching equipment, and bridge systems that distribute weight evenly. A good saddle costs between $300 and $700 and is the single most important piece of safety equipment.

Climbing Lines

Arborists use specialized ropes rated for the unique demands of tree work. The primary climbing line is typically a 12 to 13 millimetre kernmantle rope rated to hold thousands of kilograms. These ropes have a slight stretch to absorb shock, but not so much that the climber bounces around. The friction hitch or mechanical device on the rope acts as a self-braking system: if the climber lets go, they stop.

Friction Devices and Mechanical Ascenders

Gone are the days when arborists relied solely on hand-tied friction hitches. While traditional techniques like the Blake's hitch are still taught and used, modern climbers increasingly use mechanical devices like the Rope Runner, Unicender, or Zigzag. These devices allow smooth, efficient movement up and down the rope with less physical effort and more consistent braking.

Throwline and Throwball

Before a climber can ascend, they need to get a rope over a suitable branch. This is done using a throwline: a thin, lightweight cord attached to a weighted bag (the throwball). An arborist launches the throwball over a target branch, then uses the throwline to pull the climbing rope into position. In tight spaces or very tall trees, a Big Shot (a giant slingshot mounted on a pole) launches the throwball with pinpoint accuracy at heights that are impossible to reach by hand.

Personal Protective Equipment

Every climber wears a helmet rated for impact and penetration, typically with a visor and ear protection for chainsaw work. Eye protection, cut-resistant gloves, and chainsaw-resistant leg protection (chaps or chainsaw pants) are standard. When using a chainsaw above ground, the saw is attached to the climber by a lanyard so it cannot be dropped.

The Techniques: How Climbers Move Through Trees

Single Rope Technique (SRT)

SRT is now the dominant climbing method in professional arboriculture. The climber ascends a stationary rope using mechanical ascenders, similar to how a rock climber might jumar up a fixed line. SRT is energy-efficient and allows the climber to reach the top of the canopy quickly. Once in position, they can switch to a work-positioning system that allows them to move laterally through the crown.

Moving Rope Technique (MRT)

The traditional doubled-rope method is still used, especially for shorter climbs and when working in the lower canopy. The rope runs over a branch and both ends hang down. The climber ascends on one side while managing friction on the other. It is simpler to set up but less efficient for tall climbs.

Aerial Rescue

Every professional climbing arborist is trained in aerial rescue. If a climber becomes incapacitated in the tree due to a medical emergency or equipment failure, the ground crew must be able to ascend and lower them safely. This is not optional. Certified arborists practice aerial rescue scenarios regularly, and it is a required component of most arborist certifications.

The Assessment: What Happens Before Climbing

A professional arborist never just walks up and starts climbing. Before feet leave the ground, the tree gets a thorough assessment:

• Structural integrity: Are there dead branches overhead? Cracks in the trunk? Signs of internal decay?
• Target branch selection: The branch the climbing rope goes over must be alive, structurally sound, and strong enough to support the climber's weight plus dynamic loads
• Hazard identification: Power lines, dead trees nearby, wasp nests, loose bark, and widow-makers (dead branches lodged in the canopy) are all identified before climbing
• Work plan: What needs to be done, in what order, and where will cut branches be lowered or dropped

Why This Matters When Hiring

The difference between a trained arborist and someone with a truck and a chainsaw is enormous. An untrained climber using spikes to ascend a tree for pruning causes wounds at every step that invite disease and decay. A climber without proper rope systems is one slip away from a catastrophic fall. And a crew without aerial rescue training has no plan for when something goes wrong.

When you hire a tree company, ask about their climbing practices. Legitimate companies are happy to explain their safety protocols. If the answer is vague, or if you see climbers working without helmets, without visible rope systems, or using spikes on a tree that is being pruned rather than removed, those are red flags.

Professional tree climbing is one of the most physically demanding and technical trades in existence. The gear, training, and certifications that go into it are what separate safe, quality tree care from dangerous shortcuts.