Planning the future of the World Geodetic System 1984

The Department of Defense (DoD) World Geodetic System 1984 (WGS 84) defines a family of closely related global coordinate systems and Earth models that support positioning and navigation. The National Geospatial-Intelligence Agency (NGA) is responsible for insuring that the WGS 84 continues to meet the ever-increasing accuracy demands of all its users. Major users include, the Navstar Global Positioning System that provides WGS 84 positions by design, the U.S. DoD, the North Atlantic Treaty Organization (NATO), the International Civil Aviation Organization (ICAO), and the International Hydrographic Organization (IHO). Despite its name, WGS 84 is not a 20-year old system. Numerous updates have been made to various components of the system and more are planned for the future. Improvements include increasing the accuracy with which WGS is tied to the Earth, increasing the accuracy and resolution of the gravity model, incorporating a model of the Earth's magnetic field, refining the relationships between WGS 84 and other geodetic datums and coordinate systems, and improving the scope and quality of WGS documentation. This paper traces the evolution of the WGS 84 from the early 1980's to the present and describes NGA's plans to meet the future needs of WGS users.