Health and Safety Executive

Safe arboriculture and tree surgery

HSE Press Release: E075:04 - 3 June 2004

Three-way karabiners are still the best form of rope-to-harness connector for tree surgery and arboriculture but improvements are needed, say researchers at the Health and Safety Laboratory.

The findings "Karabiner Safety in the Arboriculture Industry" are published today and, if adopted by practitioners, trainers and manufacturers, will help prevent accidents and enable climbers to work with more confidence.

Main findings:

  • In treework, three-way karabiners are still the best form of connector between harness and rope equipment.
  • Karabiners need to be carefully maintained and lubricated, and replaced more often.
  • Improvements are needed to the way karabiners are used - in particular the attachment of ropes and prussik loops.
  • Manufacturers need to improve the design to ensure secure closing of the karabiner and to allow more effective maintenance.

The research was triggered by a serious accident at a college in August 2001. A climber became detached from his rope system when the karabiner opened. HSE has also had reports of karabiners not closing properly, for example through wear or because of tree debris. Some karabiners do not close reliably even when new - HSE has taken-up this problem with the manufacturers.

Climbers should make sure they carefully:

  • Check the karabiner locking action before climbing.
  • Check the gate has closed fully after each opening.
  • Follow manufacturers' instructions for use and maintenance.
  • Use recommended techniques for attaching ropes to the karabiner - as described in HSE Guidance leaflet AFAG 401.
  • Avoid circumstances where rope, strops, tree, etc., may exert force on the gate mechanism.
  • Remove karabiners from service if they fail to close properly every time.
  • Make sure karabiners are thoroughly examined every six months, as required by LOLER (see below).

Notes for editors



1. The report, Karabiner Safety in the Arboriculture Industry, is available on the HSE website at http://www.hse.gov.uk/research/hsl/engineer.htm

2. The Lifting Operations and Lifting Equipment Regulations (LOLER) 1998 apply to tree work, and HSE's guidance to the arboricultural industry is given in Agricultural Information Sheet 30 LOLER: How the Regulations apply to arboriculture.

3. AFAG 401 http://www.hse.gov.uk/pubns/afag401.pdf Tree-climbing operations is available on HSE's website.

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Updated 13.07.11