A package delivery system uses unmanned aircraft operable to transition between thrust-borne lift in a VTOL configuration and wing-borne lift in a forward flight configuration. Each of the aircraft includes an airframe having at least one wing with a distributed thrust array coupled to the airframe. The distributed thrust array includes a plurality of propulsion assemblies configured to provide vertical thrust in the VTOL configuration and a plurality of propulsion assemblies configured to provide forward thrust in the forward flight configuration. A package delivery module is coupled to the airframe. A control system is operably associated with the distributed thrust array and the package delivery module. The control system is configured to individually control each of the propulsion assemblies and control package release operations of the package delivery module. The system includes a ground station configured to remotely communicate with the control systems of the aircraft during package delivery missions.