This report is the Deliverable 2.1 R-WAKE System Specification Document, which provides the compilation of high-levelR-Wake requirements, resulting from Task 2.1 activities. More specifically, this document contains:¿An analysis of the state-of-the-art in wake vortex simulation and prediction; wake vortex separation standards and methodologies; weather data provision simulation and prediction; trajectory based operations; and methodologies for safety and robustness analysis.¿The R-Wake project detailed motivation, objectives and proposed methodology..¿The R-Wake system highlevel specification,which isone of the main contributions of this Project, to enable the realisation of several simulations and assessments of the eventual impacts of wake vortex phenomena in the en-route phase of flight.