Premature operation – is better described as “unintended” operation. An example may be an automobile airbag that is deployed at the wrong time due to incorrect or overly sensitive sensor. Or, as in the case of a recent highly publicized automotive defect, unintended acceleration is applied by the automobile’s computer due to a fault in the software. Yet another automotive defect had an incorrectly specified spring in the ignition switch that could cause the switch to turn positions by itself under certain circumstances.

Premature Operation differs from all of the others, in that ‘input conditions’ should be keeping the function fixed in a known state, but a fault (usually in the design) such as an overly sensitive sensor, incorrect logic, incorrect timing sequence, incorrect tolerances, etc. could cause it to unintentionally change states.

This differs from “Intermittent’ operation in that intermittent implies randomness, whereas Premature Operation failures are repeatable given the right set of conditions.

Paul Wagner
Senior Engineer
Reliability Information and Analysis Center
Please note that the RIAC is currently in the process of being transitioned to the newly-formed Defense Systems Information Analysis Center (DSIAC). Quanterion Solutions, Inc., as the day-to-day operator of the RIAC, will continue in this capacity as part of the DSIAC in the technical areas of reliability, maintainability and quality (RMQ). Inquiries related to RMQ can continue to be made to the toll-free number at (877) 363-7422.