When attending Micro Air Vehicle (MAV) competitions, one notices a majority of teams concentrating on the vehicle itself, be it from an aerodynamics, structures, propulsion or control point of view. A total system approach is not often seen, though MAVs pose a very unique challenge to the system designer who must propose a platform and architecture to support the autopilot, the communications, user interface, simulation, analysis and tuning tools, flight plan management and many other details. Since its inception, the Paparazzi team considered the MAV as a system and used a bottom to top approach focusing on safety, robustness and usability of the system as a whole. This paper describes the Paparazzi project approach: The complete and integrated design of hardware, software, and airframe into a robust and reliable system, proven by formal analytical methods and thousands of flight hours.