Exception-handling devices include a variety of alarm lights, switches, buzzers, and other mechanisms that operate when an exception takes place. Example exceptions could include process parameters such as temperature, pressure, flow rate, etc. that are out of specification. Another example would be a hatch or door left open on an airplane.
If exception-handling devices have a condition of incipient malfunction, then at the time that an exception takes place the needed response will not take place. By their nature, exception handling devices are not expected to be used for their intended purpose very often. Therefore, the incipient malfunction is not apparent unless actives measures are taken to test the exception-handling device.
Case studies will be presented in which an initial failure resulted in an exception that was not handled due to an incipient malfunction in the exception-handling device.
Keywords: Alarms, alerts, indicators, exception-handling