Random Failure

failure, occurring in a random way

Note 1 to entry: A random failure may be time or demand dependent. Whether it occurs or not is not predictable

with certainty but the corresponding failure rate (see 3.1.18) or probability of a failure due to demand (see 3.2.13)

may be predictable and this allows probabilistic calculations.

EXAMPLE Examples of failure mechanisms leading to unpredictable failure occurrence are: hardware

random failures resulting from degradation mechanisms; human random failure resulting from error in routine

operation, lack of attention, stress, tiredness, etc


Note 2 to entry: From the probabilistic point of view, the random failures are the contrary of systematic failures

(see 3.2.17) which occur in a deterministic way (i.e. with a probability equal to 1) when some conditions are met.

Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards

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