A capacity planning process has been implemented for more than decade and it has been recently re-enforced through the creation of the Network Manager and the implementation of the European Performance Scheme. In order to apply a consolidated and harmonised process network-wide, all involved stakeholders have to fully understand the details and the various steps of the capacity planning process and its supporting tools and data. Understanding and implementing these mechanisms is essential to improve operational performance at local and network level. This course starts with an overview of the regulatory background and then explores the various steps of the capacity planning process. The last part of the course provides in-depth knowledge about NEST, one of the main tools provided by EUROCONTROL to support network operations planning.