What does an alarm signal indicate when activated on board?

An alarm signal signifies a System Alert when activated on board. This alert serves as an immediate notification that something requires attention, potentially indicating a fault, anomaly, or critical situation that demands prompt action. Such alerts are crucial in maintaining safety and operational integrity, often prompting crew members to assess the situation, investigate the cause, and take appropriate measures.

In contrast, options like Routine Maintenance, System Shutdown, and Equipment Upgrade do not directly relate to the immediate nature of an alarm signal. A routine maintenance message would typically be scheduled and not represented by an alarm. A system shutdown could be a result of a critical failure that would need an alarm, but it is not in itself what an alarm indicates. Lastly, equipment upgrade procedures generally do not trigger alarm signals, as they are planned activities rather than reactive alerts. Therefore, the option referring to a System Alert aligns perfectly with the purpose and function of an activated alarm signal.