The modelling of loss of control

Operator performance in emergencies can be decisive for system safety. There is therefore a need of adequate models for human behaviour and human cognition. It is important in emergencies whether the operator maintains control, loses control, and/or regains control of the situation. Most models of cognition are not able to account for this. The paper proposes an alternative model, which describes adequately how actions are controlled and how control depends on the context. The consequences for system design and reliability analysis are pointed out