What is a standby power system, and how does it keep avionics powered during primary power loss?

• A. An auxiliary generator that runs all avionics continuously.
• B. A separate battery or dedicated power source that supplies essential avionics on loss of main power.
• C. A solar panel array integrated into the fuselage.
• D. A manual switch that allows backup components to be powered by hand.

Answer: (B)

A standby power system is an independent energy source that keeps essential avionics powered when the main electrical system loses power. It uses a separate battery or dedicated power source connected to a standby bus and is designed to automatically take over without pilot action as soon as main power is unavailable. This ensures critical flight instruments and avionics remain powered for a specified period, even if the main generator or bus fails. The transfer is automatic and isolated so there’s no back-feeding into the failed system.

Why the other ideas don’t fit: a generator that runs all avionics continuously would not be standby power; it relies on the primary system and doesn’t automatically preserve power when main power is lost. A solar panel array isn’t reliable for guaranteed standby power in all conditions or at all flight attitudes. A manual switch requires pilot action and could delay essential systems, whereas standby power is meant to operate automatically to protect critical functionality.