How is empty weight generally defined before any alterations?

Empty weight is defined as the weight of the aircraft without any payload, which encompasses any passengers, cargo, or usable fuel. This definition is essential in aviation as it serves as a baseline for various calculations, including weight and balance assessments. Knowing the empty weight allows pilots and maintenance personnel to determine how much additional weight the aircraft can carry and ensures it remains within safe operational limits.

Empty weight includes the aircraft’s structure, systems, and any necessary operating equipment, but does not include items that vary, such as fuel, luggage, or passengers. This distinguishes it clearly from maximum takeoff weight, which is the total weight including all payload, and from fully fueled weight, which accounts for the weight of the system’s fuel load. Additionally, total weight upon landing would represent the combined weight at that moment and does not pertain to the configuration of the aircraft before alterations. Understanding the concept of empty weight is crucial for maintaining compliance with safety regulations and ensuring effective flight planning.