Model Based System Engineering is considered today as the approach that can meet the continually growing complexity of avionics, a challenge that is compounded by constant market pressure (cost, time to market, need for product variants…) For each activity in the product life cycle, tools and technologies supporting an MBSE approach already exist, such as embedded code generation, formal safety analysis, electrical harness design; however, one of the greatest challenges consists in integrating these diverse system development tools into a global framework that ensures the consistency of perspectives and a seamless workflow across processes. Citrus is being developed as an open environment that targets the main activities of systems and software engineering: modeling and validating functions, allocating functional and non-functional requirements to systems, developing the physical architecture, interface design, allocating system requirements to software and hardware items. The Citrus approach relies on key features: efficient asset management, avionics architecture modeling languages that build on the best aspects of SysML and AADL, a rich and user-friendly architecture editing environment that facilitates the use of modeling languages, an efficient extension mechanism that makes it possible to plug specialized external tools (e.g. electrical wiring tool and software application model compilers). Finally, through early testing and analysis, requirements will be validated as they evolve and their partial implementation is verified. This paper also highlights the expected benefits of applying Citrus to a real cockpit application, guided by ARP 4754A and DO-178C.