AVAILABILITY OF A MAN-MACHINE-SYSTEM WITH CRITICAL AND NONCRITICAL HUMAN ERROR

This paper presents a newly developed probabilistic model representing two units in parallel and one on standby system with critical and non-critical human error. Repair times of the failed system are arbitrarily distributed while all other transition time distributions are negative exponential. A general formula for the system steady-state availability is developed with the aid of the method of supplementary variables, the Markov approach and Laplace transforms. Specific plots and tables are shown to demonstrate the impact of critical and non-critical human errors on system steady-state availability.