Loading of aircraft for cargo is in 3 main compartments: Bellyhold; Lower deck; and Upper deck. The Bellyhold is normally reserved for passenger baggage but is used for small size/low gross weight carton/boxes. Lower and upper deck are used for cargo loaded in specific loading units which will fit the configuration of the aircraft being used. These units are referred to as Unit Load Devices (ULD). These units vary in size depending on the aircraft type.
