What does APU loading refer to in the context of the C-130J?

APU loading in the context of the C-130J refers to the demand for electrical and pneumatic power. The Auxiliary Power Unit (APU) is a crucial component that provides a reliable source of power for various systems when the main engines are not running. When we talk about APU loading, we are specifically addressing how much power is being drawn from the APU to support aircraft systems such as air conditioning, electrical systems, and bleed air requirements for engine starting or cabin pressurization.

Understanding APU loading is vital as it affects the overall efficiency and operational readiness of the aircraft. If the demand for power exceeds the APU's capability, it could lead to operational issues. Thus, monitoring APU loading ensures that the aircraft can effectively utilize its auxiliary power without overloading the system, which could lead to failures or inefficiencies. The other options focus on different aspects of the aircraft's operations that do not specifically pertain to the power demand managed by the APU.