On the ground, which power source provides external electrical power to an aircraft when connected to the airport electrical system?

Prepare for the Aircraft Ground Exam with multiple choice questions and expert explanations. Enhance your knowledge and ace the test.

On the ground, when an aircraft is plugged into the airport electrical system, power comes from a Ground Power Unit plugged into the aircraft’s external power receptacle. This external power is supplied from the airport grid and distributed to the aircraft’s systems at the correct voltage and frequency, letting the avionics, lighting, environmental controls, and other systems run without starting the engines or using the onboard APU. The onboard APU is an auxiliary generator that can power the aircraft when external power isn’t available or for engine starts, but it’s not the external source from the airport system. Batteries can provide limited DC power for certain items, but they can’t meet the full electrical load on the ground, and solar panels are not a standard aircraft power source in this context.