There are many commercial aircraft suitable for carrying cargo such as the Boeing 747 and the bigger An‑124, which was purposely built for easy conversion into a cargo aircraft. Such large aircraft employ quick-loading containers known as unit load devices (ULDs), much like containerized cargo ships. The ULDs are located in the front section of the aircraft.
Popular commercial aircraft transformed to a cargo aircraft such as Saab 340A is designed for high revenue and profitability in short / medium haul operations.