Common Cause Failure

A common cause failure (CCF) - also refered to as Common Mode Failure - is a failure where:

• The function of multiple CI is disrupted or destroyed by the same cause or hazard affecting the CI at the same location or area in the same time frame (e.g., a hurricane blocking roads and affecting telecommunication and power lines; a collapsed bridge which blocks inland shipping, road transport and caused disruption of gas, power and telecommunication lines)
• Item failures result from a single shared cause and coupling factor (or mechanism)

Definitions

National Definitions

Australia

Common mode failure is the coincident failure of two or more independent components as the result of a single cause; of particular concern in an instrument system incorporating redundancy where an event causes coincident failure of two or more of the normally independent channels.

See also

• Geographical dependency - incorrect term often used for Common cause failure