CAS

The Crew Alert System (CAS) is a part of the EICAS system. It consists of an Alert Message Stack instrument and a bus module that drives the display.

Alert Message Stack

The messages are arranged by their urgency and order of occurrence. All crew alerting system messages are divided into one of four categories: warnings, cautions, advisories, or status.

• Warnings messages, are the most urgent type of crew alerts and indicate operational or aircraft system conditions that require immediate corrective action. All

warning messages are preceded by a triple chime and appear in red at the top of the message stack. For all warnings, the red MASTER WARNING lights will flash. Some warnings also have an aural alert consisting of a unique tone and a voice advisory.

• Cautions messages, are less urgent than warnings and indicate operational or system conditions that require prompt corrective action. All caution messages are preceded by a single chime and appear in amber immediately below the warnings in the message stack. For all cautions, the amber MASTER CAUTION lights will flash.

• Advisories messages, are used to show that a safe condition exists. They appear in green immediately below the caution messages in message stack.

• Status messages, indicate that an abnormal condition exists or that a low-priority failure has occurred. They appear in white in the message area below the advisories.

Messages cannot be removed from view, unless the applicable condition for which they have been presented has been resolved.