How is the useful load of an aircraft defined?

The useful load of an aircraft is defined as the difference between the maximum gross weight and the empty weight. This concept encompasses everything the aircraft can carry in terms of payload including passengers, cargo, and fuel.

When evaluating an aircraft's maximum gross weight, it refers to the maximum allowable weight at which the aircraft is certified for takeoff. The empty weight is the weight of the aircraft without any load, including all fixed equipment, unusable fuel, and full operating fluids. By subtracting the empty weight from the maximum gross weight, you effectively determine how much additional weight (the useful load) the aircraft can safely carry while being compliant with its operational limits.

This understanding is crucial for operational safety and efficiency, as it directly impacts aircraft performance, taking into account factors such as takeoff distance, climb rate, and fuel consumption.