What happens when the Standby Battery is switched to Arm?

When the Standby Battery is switched to Arm, it connects the Standby Battery to the Standby Bus. This action is critical because it enables the essential systems to receive power from the Standby Battery during an emergency or main power failure. The Standby Bus is designed to ensure that vital avionics and instruments remain operational when the primary power sources are compromised. By establishing this connection, pilots can have continued access to crucial information and controls necessary for navigating and maintaining safety in-flight, especially under unexpected situations.

The process of arming the battery is thereby fundamental for ensuring a backup power source is readily available and actively supporting the aircraft's systems that are needed in emergencies. This allows flight crews to manage the aircraft's operations effectively, even when faced with power loss from the main sources.