What is one item included in an aircraft's basic empty weight?

The concept of basic empty weight is crucial for understanding an aircraft's weight and balance calculations. Basic empty weight includes the airframe, engine, all permanently installed equipment, and unusable fuel along with the full operating fluids such as oil and hydraulic fluid.

Unusable fuel is essentially the portion of fuel that cannot be used during normal flight operations, usually due to the shape of the fuel tanks and the design of the fuel system. Since this fuel is part of what the aircraft holds but is not available for use in flight, including it in the basic empty weight ensures accurate weight calculations and helps prevent the pilot from exceeding the maximum weight limits when carrying passengers or cargo.

Other options, such as full fuel and usable fuel, would inaccurately represent the basic empty weight since they do not account for fuel that is practically available for flight use. Operational weight refers to the total weight including all fuel, cargo, and passengers, which is different from the basic empty weight definition. Overall, recognizing what components make up basic empty weight is essential for safe and effective aircraft operation.