The Federal Radionavigation Plan (FRP) reflects the official positioning, navigation, and timing (PNT) policy and planning for the Federal Government. Within the construct of the National PNT Architecture, the FRP covers both terrestrial- and space-based, common-use, federally operated PNT systems. Systems used exclusively by the military are covered in Chairman, Joint Chiefs of Staff Instruction 6130.01, DoD Master Positioning, Navigation, and Timing Plan (MPNTP) (Ref. 1). The FRP does not include systems that mainly perform surveillance and communication functions. The policies and operating plans described in this document cover the following PNT systems: - Global Positioning System (GPS) - Augmentations to GPS - Instrument Landing System (ILS) - Very High Frequency (VHF) Omnidirectional Range (VOR) - Distance Measuring Equipment (DME) - Tactical Air Navigation (TACAN) - Aeronautical Nondirectional Beacon (NDB) - Internet Time Service (ITS) - Radio Station WWVB signal - Two-Way Satellite Time Transfer (TWSTT) - Network Time Protocol (NTP) The Federal Government operates PNT systems as one of the necessary elements to enable safe transportation and encourage commerce within the United States. It is a goal of the Government to provide this service in a cost-effective manner, balancing costs and needed operational capabilities. The Department of Transportation (DOT) is responsible under Title 49 United States Code Section 101 (49 USC § 101) (Ref. 2) for ensuring safe and efficient transportation. The Department of Defense (DoD) is responsible for maintaining aids to navigation required exclusively for national defense. DoD is also required by 10 USC § 2281 (Ref. 3), paragraph (b), to provide for the sustainment and operation of GPS for peaceful civil, commercial, and scientific uses on a continuous, worldwide basis, free of direct user fees. The Department of Homeland Security (DHS) is responsible, in coordination with the interagency, to enhance the security and resilience of the nation’s critical infrastructure and the detection and mitigation of sources of GPS interference within the United States. A major goal of DoD and DOT is to ensure that a mix of common-use (civil and military) systems is available to meet user requirements for accuracy, reliability, availability, continuity, integrity, coverage, operational utility, and cost; to provide adequate capability for growth; and to eliminate unnecessary duplication of services. The National PNT Architecture is a framework to assist United States Government (USG) organizations with investment decisions. Selecting a future PNT systems mix is a complex task, since user requirements vary widely and change with time. While all users require services that are safe, readily available, and easy to use, unique requirements exist for military as well as civil users. For example, the military has more stringent requirements including performance under intentional interference, operations in high-performance vehicles, worldwide coverage, and operational capability in severe environmental conditions. Similarly, civil users desire higher accuracy and integrity for future aviation, highway, rail, marine, and other safety-of-life applications. Cost is always a major consideration. As the full civil potential of GPS and its augmentations is realized, the services provided by other federally provided PNT systems will be considered for divestment to match the reduction in demand, provided those services are not relied upon as a part of an integrated strategy to ensure PNT availability for critical applications or safety-of-life services. The Federal Government conducts research and development (R&D) activities relating to federally provided PNT systems and their worldwide use by the U.S. armed forces and the civilian community. Civil R&D activities focus mainly on enhancements of GPS for civil uses, but also encompass areas such as security and resilience. Military R&D activities mainly address military mission requirements and national security considerations. A detailed discussion of agencies’ roles and responsibilities, user requirements, and system descriptions can be found in this edition of the FRP. The FRP is composed of the following sections: Section 1 – Introduction to the Federal Radionavigation Plan: Delineates the purpose, scope, and objectives of the plan, including an overview of the National PNT Architecture, and discusses PNT system selection considerations. Section 2 – Roles and Responsibilities: Presents DoD, DHS, DOT, and other Federal agencies’ roles and responsibilities for the planning and providing of PNT services. Section 3 – Policy: Describes the U.S. policy for providing each Federal PNT system identified in this document. Section 4 – PNT User Requirements: Summarizes context for performance requirements of federally provided PNT services that are available to civil users. Section 5 – Operating Plans: Summarizes the plans of the Federal Government to provide PNT systems or services for use by the civil and military sectors. This chapter also presents the research and development efforts planned and conducted by DoD, DHS, DOT, and other Federal organizations. Section 6 – PNT Architecture Assessment and Evolution: Summarizes the activities and plans of the Federal Government to implement the National PNT Architecture. Appendix A – System Parameters and Descriptions Appendix B – PNT Information Services Appendix C – Geodetic Reference Systems and Datums Appendix D – Acronyms Appendix E – Glossary References