A method for developing software as a layered, segmented system having diverse functionalities, based on a software architecture and an aerial vehicle utilizing the software architecture are provided. The software architecture for the aerial vehicle, such as an unmanned aerial vehicle (UAV) includes an electrical segment, a propulsion segment, a flight management segment, a navigation segment, a data link segment, and perhaps a payload segment. Each segment includes a number of software modules and objects, and each segment interfaces with or controls one or more devices. The software architecture also includes a number of layers, including an executive layer for managing execution rates of the segments, a vehicle controller layer for coordinating activities across segments, and various layers providing utilities, common services, and computing support including operating system support. Rules of engagement guiding interaction between software entities within the software architecture are specified.