As the machine was slewing left towards a dump truck, the operator tried to stop the machine by pushing the joystick to the right but it did not respond.

The operator was able to hoist the bucket while in motion to avoid hitting the truck.

"The shovel was walked back from the face and parked up," the NSW Resources Regulator said.

"The bench was cleaned up before the scene was preserved."

The regulator said the incident cause was being investigated.

"Workers and supervisors must be trained in the required response to incidents," it said.

"This includes when escalation to management is needed and when the incident scene must be preserved."