Complex systems are designed by engineers to operate in
deterministic and static conditions, but actually operate in
stochastic or random and dynamic environments and this requires
the system to be adapted. Dr Richard Cook says that the bridge
between system theory and application is operators who are
resilient. Their resilience consists of four factors. These are
System Monitoring, Responding to Events, Adapting to Changing
Conditions of a system, and Learning How to Apply a System in
ways that differ from the way it was envisioned. Collectively
these factors bear the name of "resilience engineering" or
"system resilience". Systems in reality, or practice, are not
the same as their formal presentation, or theory. Systems are
designed to be reliable, with boundaries, layers, defenses in
depth, assurance mechanisms, reviews and interference protection
for imagined conditions. However, as soon as a system is placed
in operation it needs maintenance where maintenance is defined
as people, their training, equipme