This poster presents research conducted within COTTON project (Grant 783222) funded by the SESAR Joint Undertaking as part of SESAR 2020 Exploratory Research Programme within the framework of the EU’s Horizon 2020 research and innovation programme. COTTON is building an integrated view on future Capacity Management processes by exploring how complexity assessment could help integrating Dynamic Airspace Configuration [1] and Flight Centric ATC solutions [2] taking advantage of trajectory information that is available in a TBO environment and incorporating the uncertainty in the DCB decision-making. Inappropriate sector configuration is a major safety issue as it may result in providing in-sufficient capacity or not taking necessary actions adapt the demand to the available capacity. To address this issue, COTTON explores how the uncertainty associated with the agreed trajectory will influence the quality of the complexity predictions and the effectiveness of the airspace management. An effective complexity assessment has been specified and addressed in COTTON through the development of DAC, FCA and integrated DAC/FCA capacity management use cases, using SESAR industrial research projects definition of DAC and FCA solutions as a reference. COTTON Complexity Assessment comprises three complexity metrics, namely the Solution Space metric, the Cognitive metric and the Geometrical metric. For each of these metrics, on top of the mathematical formulation, the integration of the demand uncertainty and the method to identify the value of the capacity thresholds have been defined. FCA, DAC and integrated DAC/FCA capacity management processes have been fully reviewed to effectively incorporate COTTON complexity assessment.