What is a "usable load"?

Usable load refers specifically to the total weight that an aircraft can safely carry, which includes passengers, baggage, and cargo, while accounting for the weight of the fuel and oil that is not considered usable. The usable load is calculated by taking the maximum gross weight of the aircraft and subtracting the empty weight of the aircraft, as well as the weight of fuel and oil that cannot be used during flight (typically the fuel required for operational purposes).

The correct choice encompasses the idea that the usable load is essentially the difference between what the aircraft is capable of carrying (its maximum load capacity) and the weight already accounted for in fuel and oil that will not be used in the flight operation. This concept is crucial for ensuring that the aircraft operates within safe weight limits, facilitating optimal performance and safety.