While in flight, with all three generators offline, which buses are powered?

When all three generators are offline during flight, the electrical system of the aircraft defaults to a specific configuration to maintain critical functionalities. In this scenario, only the ESSENTIAL bus remains powered.

The ESSENTIAL bus is designed to provide power to the most critical systems necessary for safe flight operations. This includes necessary flight instruments and systems that support basic aircraft control and safety. The aircraft's electrical architecture prioritizes the stability and safety of these essential systems in the event of a generator failure.

The other buses, such as AUXILIARY, MAIN, or NAVIGATION, are not powered in this situation because they are not deemed critical for immediate flight safety and can be safely powered down to conserve energy and resources for essential operations. Hence, the focus on powering only the ESSENTIAL bus ensures that the most vital systems remain operational, allowing the pilot to manage the situation effectively.