A 34-year-old skidder operator was killed when the skidder he was operating rolled down a steep bank. He either jumped or was thrown from his machine.


The skidder was positioned at the edge of a steep bank. A short winch rope was pulled out and a strop attached to a drag. The machine was unable to winch the drag forward.

[image] Shows the bank the skidder rolled down


The investigation determined that:

  1. there were trees lying on top of the drag when the skidder began to pull the drag forward.
  2. the drag was facing directly down the slope and hooked on to the log at the butt of the tree. This may have resulted in the tree being pulled into the bank rather than up towards the skidder.
  3. During this process, the front of the skidder may also have moved sideways. While attempting to drive the machine forward, the front wheel struck a stump and this caused the machine to move further across the slope.
  4. When a winch line is high, a position necessary to haul logs, it acts as a lever when side-loading is placed on it.
  5. Factors 3. and 4. combined with the short winch rope contributed to the roll over.

WorkSafe New Zealand advice

Rollover protective structures (ROPS) are required on skidders to prevent injury to the operator. A ROPS will only be effective if the operators have their seatbelts on and remain in the cab throughout.

Selecting the drag and positioning the machine


Where stems have not been bunched, each drag must be planned.

This involves:

  • identifying where the stems are to come from
  • deciding where the machine is to be positioned to hook on or accumulate the stems
  • determining if the stems need to be bladed to a more favourable position.

Base your selection decision on the following:


Choose the top trees (last ones felled) or clear other trees or stems, logs, and branches.


Trees or stems should be aligned with the general extraction direction and within reach of the rope.


Select a combination of trees, stems, or pieces to make up an optimal drag (as big as possible without overloading the machine or ropes). to reduce the time taken to hook-on, you can blade the drag stems closer together. Be careful to avoid damaging the stems with the blade. Machine positioned for hook-on (note blade in the down position).

To which industries/sectors or matters will this information be relevant?

  • Forestry

Published: December 2010. Updated August 2017.

While this bulletin has not been updated to reflect current work health and safety legislation (the Health and Safety at Work Act 2015 and regulations), it may still contain relevant information and practices to keep workers and others healthy and safe. Please read this guidance in conjunction with all relevant industry standards that apply to you as a PCBU. This guidance will be progressively reviewed and either updated, replaced with other guidance, or revoked.

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