'Worker was careless' is not a root cause. How to find out why incidents really happen.
When an investigation ends at 'human error', the same incident will happen again. The real question is why the error was possible.
Use the 5 Whys
Keep asking why until you reach a system failure — training, supervision, design, planning — that management can fix.
Corrective actions that stick
Apply the hierarchy of controls. Eliminate and engineer before you add a procedure or PPE.
Close the loop
Track every corrective action to verified close-out. An open action register is an incident waiting to repeat.