What sources typically provide a dedicated standby power source in a standby electrical power system?

• A. A flying standby generator.
• B. A dedicated standby battery alone.
• C. A wind-up mechanical power source.
• D. An emergency generator or inverter.

Answer: (D)

Standby power in an aircraft’s standby electrical system is provided by an emergency generator or emergency inverter. This equipment is designed to automatically energize essential buses when normal power sources fail, delivering the correct voltage and frequency and for the required duration to keep critical avionics, flight instruments, and communications functioning. A dedicated standby battery alone usually cannot sustain all required loads for the necessary time, though it may support limited operations or start the emergency generator/inverter. A wind-up mechanical power source is impractical for modern aviation and not used, and a term like flying standby generator isn’t a standard concept for how standby power is supplied.