Method and specification tools for Airbus onboard systems

Abstract Aerospatiale Avions uses a method, a language and tools to obtain detailed specifications of the Airbus onboard flight control systems under its responsibility. The origins of this workshop developed by Aerospatiale lie in the SAO (computer assisted specification) language based on a graphics formalism, known to all electronics and automation experts, which covers the field of flight control laws and operational logics. The possibility of automatically generating software from this formalism has allowed Aerospatiale to develop tools for real-time simulation and critical system specification validation as early as the design stage. The specifications thus validated are then automatically translated into ‘aircraft’ software, guaranteeing that the behaviour of the onboard system will be identical to the behaviour observed during simulation. This method and these tools were put to the test and proven within the scope of the Airbus A340 development. The quality of the specifications thus obtained enabled a significant reduction in the number of modifications to the onboard systems and led to substantial cuts in cost and debugging times. The example of debugging the Airbus A340 fly-by-wire specifications is used to back up the paper, which will also present the future specification integrated workshop, CSAO (computer-aided specification and design), developed by Aerospatiale Avions and Verilog.