"This document presents the technical solution proposed by a consortium formed by ENVISA (a French R&D SME) and Brunel University (UK) in reply to the call for proposals for the Clean Sky topic “Advanced Turbofan Engine Emissions Model” (short name: TURBOGAS). The ENVISA team has worked in the field of aviation environmental impact modelling for over ten years, including developing and validating emission models with experimental flight data, and participates in international expert working groups (such as the ICAO Committee for Aviation Environmental Protection). The Brunel team will be composed of highly skilled software developers with experience in aviation environmental modelling. The TURBOGAS project will develop a model to compute fuel burn and emissions based on discrete aircraft trajectories and meteorological parameters. The model will be structured around four principal modules. One will be in charge of the thrust to fuel flow conversion, considering both operational and procedural parameters (aircraft speed, flaps configuration, corrected net thrust, etc), as well as the ambient conditions along a flight trajectory. A second module will adjust the emission indices. Fuel flow and emission indices for various discrete points along an entire trajectory will then be aggregated in another module to calculate the total fuel burnt and the emissions of CO2, NOX, H2O, particulates, etc. The thrust to fuel flow conversion and the emission indices adjustment algorithms will be based on the latest methods developed by the ICAO working groups or from the SAE standards, in order to ensure a robust validation of the model. Finally, the fourth module will couple the water emissions with operational and meteorological parameters to estimate the occurrence and lifetime of contrails. One of the many advantages of a modular approach is that a single module can be updated with the latest methodological advances without modifying the rest of the software."