Flow assurance studies centre around the detection of specific phenomena that are a function of the fluid PVT or the pipeline hydraulics (e.g. Terrain induced or hydro-dynamic slugging, liquid loading, wax formation, hydrate formation, etc.). GAP harnesses all the existing functionality from PVTp and PROSPER to detect these phenomena across the entire surface network, and provide information that will address flow assurance challenges over time. GAP Transient extends this functionality into the realm of dynamic multi-phase flow modelling, seamlessly switching between steady-state and transient modelling. This allows the engineer to optimise and forecast using the state-of-the-art integrated modelling capabilities of GAP and then evaluate the dynamic response of any optimisation strategies that are determined or any flow assurance aspects that are predicted.