The system, briefly
A professional tree climber works on a rope and harness system, anchored to a point in the tree, with a friction device or mechanical ascender controlling their position.
Two approaches dominate. Moving rope systems run the rope over a branch union and back down, with the climber moving on a friction hitch. Stationary rope systems anchor the rope at a fixed point and the climber ascends the line with mechanical devices. Both are legitimate; the choice depends on the tree and the work.
Once at working height the climber positions with the climbing line plus a work positioning lanyard around the stem — two points of attachment whenever a saw is running, which is the single most important rule in the job.
The anchor is everything
Nothing in the system matters if the anchor fails.
A climber assesses the intended anchor before committing weight: its diameter relative to the loads expected, the species and the condition of the wood, the shape and integrity of the union, any sign of decay, cavity or included bark, and its position relative to where the work has to happen.
On a defective or dead tree there may be no sound anchor in the tree at all. In that case the anchor becomes an adjacent tree, an elevated work platform, or a crane hook. Deciding that a tree is unclimbable is a professional judgement, not a failure — dead trees are where climbers get hurt.
The ground crew is not optional
A climber alone in a tree has no rescue.
The ground worker manages lowering lines through a friction device, keeps the drop zone clear, feeds the chipper, watches the climber, maintains communication, and — the part that matters — is trained and equipped to perform an aerial rescue if the climber is injured, suffers a medical event or is incapacitated by a saw injury.
Aerial rescue training is part of the qualification for a reason. If a crew turns up with one person and a chainsaw, that is not a crew.
Chainsaw work at height
One-handed saw use is sometimes unavoidable at height but is high-risk and should be minimised. Cut-resistant leg protection, helmet with eye and hearing protection, and gloves are standard. A saw is attached to the harness so it cannot be dropped on the ground crew.
Every cut is planned before it is made: where the piece goes, whether it is rigged, where the climber will be when it releases, and what the stem does once the weight comes off.
Spikes and when they are acceptable
Climbing spurs are fine on a removal, because the puncture wounds are irrelevant to a tree that is coming down. They are not acceptable on a tree that is being pruned and retained, because the wounds provide entry points for decay.
If you are paying for a crown reduction on a tree you intend to keep, watch whether the climber puts spikes on.
The standards behind it
Australian Standard AS 4373 sets out how amenity trees should be pruned. Work health and safety law imposes duties on the contractor for safe systems of work, training and equipment. Insurance requirements sit over the top of both.
What this means for you as a customer
Ask what qualification the climber holds. Ask how many people are coming. Ask whether spikes will be used if the tree is being retained. And ask for the public liability certificate of currency — the about page covers the full list of things worth checking.
The techniques guide covers what happens once the climber is up there, and the crane guide covers the alternative.
Frequently asked questions
What qualification should a tree climber hold?
An AQF Level 3 certificate in arboriculture is the working standard for climbing and cutting in Australia, alongside current first aid and, where relevant, aerial rescue training. Level 5 is a consulting qualification for assessments and reports rather than climbing. Ask what the person going up the tree holds, and do not accept experience alone as a substitute for training in rescue.
Why does a climber need a ground worker?
Several reasons, and one of them is not optional. The ground worker manages the lowering lines, keeps the drop zone clear, feeds the chipper and handles communication. Critically, they are also the person who performs an aerial rescue if the climber is injured or incapacitated in the tree. A climber working alone has no rescue plan, and that is a serious safety failure.
What is an anchor point and how is one chosen?
The anchor is the union or limb the climbing rope is installed over, and everything depends on it. A climber assesses it for size relative to the load, species and wood condition, the angle and integrity of the union, signs of decay or included bark, and its position relative to the work. On a defective tree the anchor may be a neighbouring tree or a crane hook instead.
Is a spiked climb bad for the tree?
Climbing spurs puncture the bark and cambium at every step, leaving wounds that can admit decay. They are accepted practice on a tree being removed, where the wounds do not matter. They should not be used on a tree that is being pruned and kept. A contractor spiking up a tree you intend to retain is causing damage you will be living with.