In many aircraft, which DC bus supplies power to avionics and essential avionics equipment?

• A. Main bus
• B. Essential (or emergency) bus
• C. Auxiliary bus
• D. Avionics/essential avionics bus

Answer: (D)

Powering avionics from a dedicated DC bus keeps flight-critical electronics alive even when other systems are shed or a primary power source is unavailable. The avionics/essential avionics bus is designed to feed the flight deck computers, navigation, communication gear, and related equipment, often with a standby or alternate power path to maintain operation during abnormal conditions. In contrast, the main bus carries many nonessential loads, and the essential (or emergency) bus focuses on the most critical systems, not the entire avionics suite. The auxiliary bus serves other specific functions but does not provide the dedicated, reliable path needed for the avionics gear. So, the correct choice is the avionics/essential avionics bus, which ensures avionics equipment remains powered when other loads may be interrupted.