Why is it important to turn on the right battery first?

Turning on the right battery first is crucial primarily to prevent uncommanded Auxiliary Power Unit (APU) starts. When the right battery is activated first, it allows for proper sequencing and management of power systems in the aircraft. This helps ensure that any systems relying on the battery power are properly configured and monitored, minimizing the risk of unexpected behaviors, such as the APU starting unintentionally.

While maximizing battery efficiency, ensuring correct boot-up of aircraft systems, and maintaining cabin pressure are all essential considerations in aircraft operations, they do not specifically address the immediate operational concerns that arise from battery management and power sequencing. By prioritizing the right battery, the risk of uncommanded starts is mitigated, contributing to safer and more controlled aircraft operations.