In operational terms, the APU primarily helps with what aspect of the aircraft?

The APU, or Auxiliary Power Unit, plays a crucial role in starting the aircraft engines. It provides the necessary electrical power and pneumatic pressure needed to commence the engine start sequence. This function is vital, especially in situations where external power sources may not be available or when ground support equipment is not present.

In addition to engine starting, the APU also supplies energy for various aircraft systems when the main engines are not running, such as environmental control systems and electrical power requirements on the ground. However, its primary and most critical operational function is the initiation of engine start, which allows the aircraft to become operational efficiently and safely.