National Air Cargo, in no way related to the two incarnations of National Airlines, does not offer regular cargo flights. They rely on other major airlines from around the world to operate most of their customers' needs. But they do provide charter cargo flights with their fleet. In other words,if a customer needs a shipment to be flown at a certain time to a certain place, the customer might be able to have his or her cargo flown on a National Air Cargo plane.
Model airplane wise, National Air Cargo had a contract with Wooster Plane Models.