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Arborist fell 50 feet when flipline broke

Date of incident: March 2015
Notice of incident number: 2015145130068
Employer: Tree service company

Incident summary
An arborist delimbed and topped an approximately 17metre (56foot) tree. He climbed the tree to 15 metres (50 feet) and was beginning to remove the first top section. He had placed a backcut and undercut and began to push the 2metre (6½-foot) section (on a zip line) to the groundsman below. The arborist’s flipline (steelcore lanyard) failed and he fell to the ground, sustaining fatal injuries.

Investigation conclusions


  • Poor condition of the flipline. The cause of this incident was a failure of the flipline wire rope. The wire rope strands failed at a point between the thimble and the swaging due to a combination of continual bending, rusting, and galvanic corrosion.

Contributing factors

  • Lack of appropriate inspection of the flipline. The arborist did not inspect his flipline effectively to ensure that it was safe for use. The design of this flipline was such that there were plastic covers over the metal crimped end, making it difficult to view any potential damage inside the crimp. However, there was enough outer damage to the flipline that was easily visible and would have indicated likely damage beneath the outer sheath.
  • Good industry practices about using a second tie-in point were not observed. Industry standards and safe work practices for arborists emphasize that when a power saw is being used in a tree, the arborist must be attached at two points. A second point of attachment must be used at all times except in circumstances where the hazards of using it are greater than not. Every effort must be used to eliminate these hazards, so the worker can use a second point of attachment. A second attachment (a workpositioning lanyard or double tiein technique) is to be used in addition to the climbing line upon reaching each work position and for the duration of work at that location. The arborist was only tied in at one point.

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Publication Date: Jul 2017 Asset type: Incident Investigation Report Summary NI number: 2015145130068