ABSTRACT
Dependent failures are internationally acknowledged as a significant factor in systems safety and reliability. Most interest has centred on common cause, or mode, failure but other forms of dependency, such as time between failure, can play a major role. Common cause failure is considered here in its most intuitive sense and covers all cases of multiple failures for which it is possible to discover a common causal event – a root cause. On the other hand, time between failure broadly describes dependency through time, both within and between items of equipment.
