Safety alert 23/2009 - Dislodged wire rope sling

This publication is for: 
Employee / workerEmployer

An unloaded steel wire rope sling dislodged from the ramshorn hook on the main block of a 150 tonne crawler crane, falling approximately 30m and striking an employee, causing fatal injuries.

While the crane was being manoeuvred to a lay-down location, the crane operator spragged to change direction, causing the sling to swing erratically and causing a sling to pass over the spring-loaded safety latch on the ramshorn hook, releasing the sling from the ramshorn hook.

The crane operator was preoccupied operating the crane and did not see the rigger in front of the crane directly under the hook load.

Contributing factors 

  • Operators of mobile plant often have severely restricted visibility of ground workers, particularly those close to the plant.
  • The operator did not rely on the rigger to direct him while moving the crane.
  • Severe crane side movements may cause slings to roll over the safety latch and be dislodged from the hook.


  • When chains or slings are not in use they should be removed from the hook to avoid accidental dislodgment.
  • As far as practicable, loads including slings are not to be suspended over or travel over a person.
  • Exclusion zones and/or spotters are to be used when manoeuvring a crane or jib with a load or slings on a hook over personnel.
  • Use a ‘sling restraint device’ if a sling or slings are to remain on the hook.

Further information

•    Nationally approved assessment instrument for Dogging, National Standard for Licensing Persons Performing High Risk Work.

Further information can be obtained from WorkSafe’s website or by contacting customer service on 1300 307 877 or email

This Alert contains safety information following inquires made by WorkSafe about an incident or unsafe practice. The information contained in this Alert does not necessarily include the outcome of WorkSafe’s action with respect to an incident. WorkSafe does not warrant the information in this Alert is complete or up to date and does not accept any liability to any person for the information in this report or as to its use.

Last updated 29 Jun 2017

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