This paper presents a benefits assessment methodology for an air traffic control tower advanced automation system called the Tower Flight Data Manager (TFDM), which is being considered for development by the FAA to support NextGen operations. The standard FAA benefits analysis methodology is described, together with how it has been tailored to the TFDM application to help inform the development process and the business case for system deployment. Parts of the methodology are illustrated through data analysis and modeling, and insights are presented to help prioritize TFDM capability development.