Annunciator panel

[1] Lamp colours are normally given the following meanings: The annunciator panel may display warnings or cautions that are not necessarily indicative of a problem; for example, a Cessna 172 on its after-landing roll will often flicker the "Volts" warning simply due to the idle throttle position and therefore the lower voltage output of the alternator to the aircraft's electrical system.

On some aircraft (most Boeing airliners, for example) the "masters" will also flash briefly and the audible alert will sound whenever the autopilot is disconnected, as an additional reminder to the pilots that manual control is now required.

In industrial process control, an annunciator panel is a system to alert operators of alarm conditions in the plant.

Lamps in each window are controlled by hard-wired switches in the plant, arranged to operate when a process condition enters an abnormal state (such as high temperature, low pressure, loss of cooling water flow, or many others).

Single point or multipoint alarm logic modules operate the window lights based on a preselected ISA 18.1 or custom sequence.

Secondly, the analysis of plant failure modes is leading to the separation of critical alarm monitoring and process control systems for safety reasons.

The annunciator panel will indicate the system status using lamps (or LEDs), an audible warning tone, and depending on the system technology, the exact location or approximate physical location of the source of a fire alarm in the building.