Which power source powers essential avionics during initial power-up when external power is unavailable?

Which power source powers essential avionics during initial power-up when external power is unavailable?

• A. External power
• B. Generator power
• C. Aircraft battery
• D. Pneumatic power

Answer: (C)

During initial power-up, the essential avionics rely on the aircraft’s internal power path that keeps critical systems alive even when no external power is connected. The aircraft battery provides the energy to energize the essential electrical buses, allowing the flight deck equipment, displays, and flight computers to boot and operate. This battery also supplies the power needed to start the APU, so once the APU generators come online they take over powering the system. Pneumatic power isn’t used to run avionics, and external power isn’t available in this scenario, so the battery is the source that gets the essential systems up and ready.

During initial power-up, the essential avionics rely on the aircraft’s internal power path that keeps critical systems alive even when no external power is connected. The aircraft battery provides the energy to energize the essential electrical buses, allowing the flight deck equipment, displays, and flight computers to boot and operate. This battery also supplies the power needed to start the APU, so once the APU generators come online they take over powering the system. Pneumatic power isn’t used to run avionics, and external power isn’t available in this scenario, so the battery is the source that gets the essential systems up and ready.