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Worker seriously injured in fall while topping trees

Date of incident: September 2012
Notice of incident number: 2012161750180
Employer: Independent tree climber; tree-thinning company as prime contractor

Incident summary
Two tree climbers were working in the tree canopy topping tall trees at the end of a runway at an airport. The process required the workers to top a tree and then move from one tree to the next using a strap-to-strap method. One tree climber was working at a height of 24 metres (79 feet). The exact sequence of events is not known, but it is likely that only one strap was engaged at the time of the incident and the snap hook rolled out from the harness D-ring. The tree climber fell to the forest floor and sustained serious injuries.

Investigation conclusions
Causes
  • Tree climber fell while working at height without fall protection: The tree climber was working at height but was not using a fall protection system. A snap hook rolled out of his harness D-ring, and he fell 24 metres (79 feet) to the forest floor and sustained serious injuries. The lack of a proper fall arrest system independent of the work-positioning system was a causal factor in this incident. The procedure used by the tree climber did not include personal fall protection. If that was not practicable, a procedure that is acceptable to WorkSafeBC should have been developed and implemented to ensure that the risk of a fall to workers was minimized.
Underlying factors
  • Improper use of equipment: The equipment in this case was not being used according to the instructions of the manufacturers of the harness and snap hook. The equipment should not have been used for fall arrest. Also, the manufacturer did not allow multiple attachments on the harness D-ring. Failure to understand and follow the manufacturers' instructions was an underlying factor in this incident.
  • Inadequate visual inspection of equipment: The workers involved in this incident were not qualified by any means other than experience using this equipment. Their visual inspections of this equipment failed to recognize the worn snap hook. A self-locking snap hook rolled out of a harness D-ring as a result of wear to the gate keeper and gate mechanisms that went undetected by either worker. The metal on the gate keeper was worn to the point that the snap hook should have been removed from service long before this incident. A lack of training in the inspection of fall protection equipment such as snap hooks was an underlying factor in this incident.
  • No fall protection system or plan in place: The prime contractor did not meet its obligation to ensure that its contractors had a fall protection system for the work area and that the work was completed in accordance with the Occupational Health and Safety Regulation. A lack of planning for fall protection by the prime contractor, which would include a documented fall protection plan, was an underlying factor in this incident.
  • Incompatibility of equipment: The tree climber did not take into account the condition of the snap hook on the flipline or the compatibility of the snap hook with the D-ring on the climbing harness. The snap hook and the D-ring were incompatible because the D-ring was too small for the snap hook; this enabled the snap hook to position itself against the D-ring in a way that puts pressure on, or loads, the gate. The snap hook could then roll out of the D-ring. A lack of understanding of the incompatibility between the snap hook and the harness D-ring due to their respective sizes was an underlying factor in this incident.

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Publication Date: Sep 2012 Asset type: Incident Investigation Report Summary NI number: 2012161750180