6.2 How Do Incidents Happen?

Incidents are rarely caused by one factor. Usually there are several contributing factors, some obvious and immediate and some less obvious and underlying.

• Immediate causes are unsafe acts or failures to act, such as using equipment with missing guards, bypassing interlocks or wearing the wrong PPE, and unsafe conditions such as damaged tools, high noise and poor lighting.
• Underlying causes are the factors that allow the unsafe acts and conditions to exist. Most are connected with how the organisation manages safety and health and how people see risk.
• Root causes are the factors from which the other causes spring. If a root cause were corrected, the undesired event would not have happened. It is unusual for an incident to have only one root cause.

Only a proper investigation finds the root causes. It is important to find out what happened, and equally important to find out why.

An example: a Friday afternoon in a depot

You manage a distribution depot, and it is Friday afternoon near the end of the day. A warehouse operative has had enough and decides to leave early. In the warehouse a forklift driver, just as keen to finish, drives a truck loaded with boxes of paint at speed along an aisle towards the loading bay.

At that moment the operative comes out of an aisle that he is not allowed to use, not looking where he is going, on his way to a fire exit that is a short cut to the car park. The driver sees him at the last moment and brakes hard, but the truck skids on a patch of oil from a leaking forklift. It stops abruptly and the load falls on the operative. He breaks an arm and bruises a leg.

You find the causes by following the links between the incident and the other facts.

A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.