What does APU stand for in aviation terminology?

In aviation terminology, APU stands for Auxiliary Power Unit. An APU is a small engine located on an aircraft that provides energy for functions other than propulsion. This includes supplying electrical power, air conditioning, and bleed air for starting the main engines. The APU is particularly useful when an aircraft is on the ground, as it allows the aircraft to operate some systems independently without the need for engine power or external power sources.

Understanding the role of an APU is essential for ramp agents and ground crew, as they may need to operate or monitor the APU during their duties, ensuring it is functioning properly to provide necessary power to the aircraft while it is on the tarmac. This knowledge helps in maintaining the safety and operational efficiency of ground operations.