Formulas of the Probabilistic Metric for Random Hardware Failures to Resolve a Dilemma in ISO 26262

The second edition of ISO 26262, which is the functional safety standard for automobiles, came into effect in 2018. One of the improvements over the first edition is the revision of the probabilistic metric for random hardware failures (PMHF) formula. The PMHF is the time-averaged probability of the violation of a safety goal (VSG) leading to inoperability during the life of a vehicle; it is a crucial metric since it is one of the target values for the hardware design of an automobile's electronic control unit (ECU).