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 arbitrari ly distributed while all other transition time distributions are negat ive exponential. A general formula for the system steady-state availab ility is developed with the aid of the method of supplementary variabl es, the Markov approach and Laplace transforms. Specific plots and tab les are shown to demonstrate the impact of critical and non-critical h uman errors on system steady-state availability.