The scope of this thesis is to do the optimization of an aircraft’s environmental control system (ECS) and flight control system (FCS) from a systems architecture perspective and from a family concept design problem. From a systems architecture perspective because the optimization goal is about the overall configuration of the system, not of one single component or function. And family concept design because its goal is to optimize several aircraft at the same time. This means, generally speaking, that the optimization should find the optimum ECS and FCS architecture configurations for each member of a new aircraft family. This problem requires aMulti-disciplinary Design Optimization (MDO) approach since it involves more than one discipline (thermodynamics, costs, aircraft performance. . . ). And will be part of a bigger optimization problem (On-Board Systems Optimization). One of the main problems with these kinds of optimizations is that architectures are discrete variables, and the quantification of the decision of choosing that configuration among the others is not clear. For this reason, optimization based on gradient methods is discarded and the main tools used are genetic algorithms (heuristic methods).Now, the main concepts are going to be explained more in depth and after the main design variables, parameters and optimization objectives are shown.