Automation in routine operation

Automation replaces manual operation. It is used

to release operator's mental resources in favor of the primary tasks
when manual operation might fail, for example, when the manual operation requires fast, complicated calculations.

Process control - in normal operation, certain risk variables may be checked, to make sure that they are in a predefined range of safe values. The machine computer calculates the deviations in production and other performance variables, and checks the source for these deviations. When the source is due to slight values of the operational conditions, the computer can compensate for it by changing the values of the parameters that affect the production and the performance variables. This method is commonly implemented in Statistical process control ( SPC )
Aviation safety - automation enable discharge of the mental load of the crew. For example, one of the duties of the Boeing 747-200 during the flight was to balance the fuel between the various tanks. This duty became redundant in the more advanced 747-400 airplane, as the pilots could do it now with the airplane computers (http://www.jnd.org/dn.mss/Norman-overautomation.pdf ) .