What does "useful load" refer to in aviation?

Useful load in aviation is defined as the difference between the takeoff weight of the aircraft and its basic empty weight. This concept encompasses the total weight of all items that an aircraft can carry, which includes passengers, cargo, and usable fuel.

Basic empty weight refers to the weight of the aircraft with all its necessary components, including the airframe, engine, and systems, but excludes any usable fuel or payload. By subtracting the basic empty weight from the takeoff weight, you determine how much additional weight the aircraft can safely carry in terms of passengers, cargo, and fuel.

This definition underscores the importance of understanding weight and balance in aviation, as exceeding the useful load can lead to safety issues during flight operations.