What is the capability of both the MAIN and APU battery?

The capability of both the MAIN and APU battery providing 30 minutes of DC emergency power is integral to aircraft safety protocols. This duration ensures that during an emergency situation, the essential electrical systems remain operational long enough for critical procedures, such as safe landings or system checks, to be performed.

The design of aviation systems accounts for various scenarios where power loss might occur, and having a robust backup power source that can sustain functions for 30 minutes is a standard safety measure. This timeframe allows pilots and crew to manage the situation effectively, whether it's addressing mechanical failures or ensuring passenger safety.

Other options suggest durations or capabilities that may not align with the established performance of these batteries, leading to potential misunderstandings of their role and importance in emergency scenarios. Understanding the actual capability ensures proper preparation and response in case of power failures during flight operations.