Integrated modular avionics (IMA) architecture is a trend in current avionics that employs a partitioned environment in which different avionics functions share a unique computing environment. UAS avionics, especially in small UAS, are usually of less complexity than not the present on airliners, however, in real autonomous UAS, the onboard avionics should control not only the flight and navigation but also the mission and payload of the aircraft. This involves more complex software as it should implement ldquointelligentrdquo or at least autonomous behavior. This need of both flexibility and complexity management while keeping low costs in the UAS avionics field requires new architectures to cope with. In this article, we describe a modular avionics architecture based on services. The avionics functionality is divided in distributed elements, the services, which are interconnected by a communication middleware. This article also proposes a configuration and deployment infrastructure and its related procedures that complete our vision of UAS avionics.