PSA Airlines Canadair Regional Jet Systems (PSA-CRJ) Practice Exam 2025 - Free CRJ Practice Questions and Study Guide

The readiness of the Auxiliary Power Unit (APU) generator for electrical loading is indicated by a green light on the start/stop switch. This green light signals that the APU has successfully gone through its start sequence, is operating properly, and is now ready to supply electrical power to the aircraft's systems.

The color green in aviation systems universally denotes a safe and operational condition, which is critical for pilots and crew when assessing the readiness of various components. In the context of the APU, this confirmation allows the crew to confidently load the generator with electrical demands necessary for the aircraft's operations.

Other indications such as a red light on the start switch typically suggest a malfunction or need for attention, while flashing yellow lights usually indicate a caution or warning status that requires further investigation. No indication light would imply that the system is either off or not operational, which does not meet the condition required for the APU generator's readiness. Thus, the green light serves as the clear and definitive signal that the APU generator is prepared to safely handle electrical loading.