In an automated system, two roles are left to humans: monitoring that the automated system is operating correctly, and taking control if it isn’t. An operator who doesn’t routinely operate the system will have atrophied skills if ever called on to take over.
Unfortunately, physical skills deteriorate when they are not used, particularly the refinements of gain and timing. This means that a formerly experienced operator who has been monitoring an automated process may now be an inexperienced one.
Not only are the operator’s skills declining, but the situations when the operator will be called upon are by their very nature the most demanding ones where something is deemed to be going wrong. Thus, what is really needed in such a situation is a more, not a lesser, skilled operator. To generate successful strategies for unusual situations, an operator also needs a good understanding of the process under control and the current state of the system. The former understanding develops most effectively through use and feedback (which the operator may no longer be getting the regular opportunity for); the latter takes some time to assimilate.