Catastrophic incident while inspecting Top Drive on the rig

This is purely for learning purposes. You can see what happen in the footage below. Three man were inspecting the top drive system on the rig floor. All the sudden the drilling link was accidentally released and it hit these guys.

What can we learn from this video?

Energy isolation – Energy (electric and hydraulic) is not properly isolated so when the man accidentally operate the top drive link tilt, the link is moved without any warning.

Trapped energy – It might have trapped hydraulic pressure in the system. People may not recognize this point.

Line of fire – The team is not aware of line of fire and what if if the link is released.

Incorrect procedure – Based on the footage,┬áthe guy who is standing in the back moves back behind may some mechanism resulted in the link moving and crushing another man.

How can we prevent this from happening it again?

Please feel free to share your thought on how to prevent this accident in the comment box below.