Via what control mechanism is the avionics bus isolation switch commonly operated on modern aircraft?

• A. Direct handheld switch
• B. Electrical control unit
• C. Manual mechanical lever
• D. Hydraulic actuator

Answer: (B)

In modern aircraft, the avionics bus isolation switch is driven by an electrical control unit. The ECU monitors bus status, faults, and power sources, and it electronically commands the isolation accordingly. This setup allows automatic or computer-assisted isolation to protect the avionics from faults, prevent backfeeding, and ensure proper power-up/down sequencing. A direct handheld switch, a manual mechanical lever, or a hydraulic actuator would require more manual intervention and isn’t how these systems are typically controlled today.