Summary: Two general classes of navigation systems are radionavigation systems which consist of transmitters and receivers and self-contained systems which depend on internally generated radio signals or other means. A review covered 13 major enroute navigation systems, 11 radionavigation and 2 self-contained, used by civilian and military travelers and by the military to improve the accuracy of weapons delivery.
Overlapping navigation systems have proliferated because it has been costly to abandon older systems as new ones are developed. Of the 13 systems (1 was terminated after the review), only 4 and parts of a 5th may be required in the future because the military NAVSTAR satellite development has the potential for meeting the navigation needs of nearly all users. Departments and agencies plan to spend $277 million over the next 3 or 4 years for equipment or development of potentially unneeded systems. A Government-wide navigation plan is needed to reduce the proliferation and overlap of navigation systems, and a strong management focus is also needed. The Congress may have to decide whether a civil or military agency should manage the NAVSTAR navigation satellite system, recognizing that civil operation may encourage earlier civil and international use but that military operation may be needed to deny high accuracy signals to hostile forces during a war or national emergency.
