The Federal Aviation Administration (FAA) has established specific goals for modernization of the National Airspace System (NAS) over the next decade. These goals include the replacement and modernization of aging air traffic control and navigation equipment and the development of a more comprehensive and coordinated system design to reflect specific needs of the user and specialist communities, to enhance safety, to improve efficiency and capacity, and to reduce operating costs. The programs to achieve these objectives are documented in the Capital Investment Plan (CIP). In conjunction with the CIP, the FAA has prepared system engineering management documents to assist in the orderly development and integration of CIP programs. The NAS Systems Requirements Specification (NASSRS) is a compilation of requirements which describe the operational capabilities for the NAS as envisioned to exist by the year 2000. The organization of this NAS Operational Concept corresponds to the major paragraphs of the NASSRS and provides an in-depth discussion of the higher level descriptions found in the NASSRS. This operational concept provides an overview of the NAS along with operational sequence diagrams and operational scenario diagrams to amplify the eight major sections of the NASSRS ... Flight Planning, Air Traffic Control & Airspace Management, Monitoring, Navigation, Air Defense, Maintenance, System Effectiveness, Communications.