What is the benefit of proper APU operation during ground missions?

The benefit of proper APU operation during ground missions is primarily the immediate power supply and support for ground operations. The Auxiliary Power Unit (APU) is designed to provide electrical power and pneumatic pressure when the aircraft is not in flight. This allows the aircraft's systems, such as hydraulic pumps and environmental control systems, to function without relying on the main engines, significantly enhancing operational efficiency on the ground.

Utilizing the APU provides the necessary power needed for critical systems while the engines are off, facilitating tasks such as engine starts and preflight checks without increasing wear on the main engines or consuming additional fuel unnecessarily. This capability ensures that ground operations can proceed smoothly and effectively without interruptions or delays due to power-related issues.

While reduced pilot workload, better fuel management, and increased aircraft speed are essential considerations, they do not directly highlight the fundamental purpose and immediate advantage provided by the APU during ground operations as clearly as the provision of immediate power and support does.