Abstract
The process industries place great reliance on layers-of-defenses, or barrier thinking, to protect against incidents. Human performance continues to be the single most widely relied on barrier: whether as a control in its own right, or in implementing, inspecting, maintaining and supporting engineered controls. Human error also continues to be a significant threat to the reliability of engineered and organisational defences. Many organisations struggle to know how to ensure the human defences they rely on are as robust as they reasonably can be when layers-of-defences strategies are being developed and implemented. Drawing on real-world incidents, this paper considers why organisations find it so difficult to know how to address human factors in their layers of defences strategies. Organisations can improve the strength of their human defences by being clearer about exactly what it is they expect and intend of human performance in their operations.
