The plant serviced by the control room is physically large perhaps many stories high and many hectares in extent. Operators need to understand the physical topology of the plant. The system is typically open that is, there is always the possibility of completely new events which have not been foreseen by designers. The system changes over time. It is never possibgle3 to know all the properties of a system, and many variables may not be observable Events take place in real time and against deadlines.
Systems are dynamic on many different time scales.
Cognition is often externalised through notes, computers, etc. Not all knowledge is in the head of the person thinking. Cognition is typically social and takes place among the members of teams and groups. Problems are seen as about physical causality, not about logical consistency. Because of the limits of attention dynamics, not all variables are monitored by operators, Instead they make use of mental models which are homomorphic mappings of the physical system.