Year 2000 Computing Challenge

The Global Positioning System, in addition to being the military's primary radionavigation system, has become crucial to many civilian applications and industries, including emergency services, airlines services, commercial fishing and shipping, corporate vehicle fleet tracking, and surveying. The system also plays an important role in communications networks and the Internet. This testimony discusses the threat posed to the Global Positioning System by the Year 2000 computing problem and the way that the system keeps track of time.

GAO noted that: (1) GPS is affected by both the year 2000 computing problem and an upcoming end-of-week rollover; (2) the upcoming end-of-week rollover is a problem that will occur for the first time on August 21, 1999; (3) instead of using calendar dates, GPS counts weeks, and seconds within a week, from precise clocks on the satellites; (4) this is based on how the signal codes transmitted by the satellite are generated; (5) GPS started at week zero on January 6, 1980; (6) because of its design, the GPS time counter starts over after counting 1,024 weeks; (7) the end of the 1024th week will occur, for the first time, on August 21, 1999; (8) there are three GPS components that may be affected by the year 2000 problem and the end-of-week rollover--space, control, and user; (9) the Air Force Materiel Command (AFMC) reports that the satellite support systems are end-of-week rollover compliant, but that they are not yet year 2000 compliant; (10) AFMC reports that these systems are in the process of either being replaced or renovated and tested; (11) according to AFMC, the ground support systems and user component systems are both year 2000 and end-of-week rollover compliant; (12) according to the Coast Guard Navigation Center, however, the accuracy of navigation on some older GPS receivers may be severely affected by the end-of-week rollover; (13) several activities are ongoing to raise awareness among owners of older GPS receivers of the upcoming end-of-week rollover problem; (14) the Coast Guard Navigation Center has been assigned with responsibility of being the government liaison to the civil sector for GPS; (15) its Internet website explains the potential rollover problem on older receivers and provides an extensive list of manufacturers and points-of-contact; (16) the Air Force has provided a list, also available on the Internet, of specific receivers that have been tested and found to be compliant by the Department of Defense; (17) furthermore, the President's Council on Year 2000 Conversion's Internet site provides links to sources of GPS Year 2000 and end-of-week rollover information; and (18) these activities are important and should be useful to GPS users seeking to determine whether their receivers will operate correctly at the end-of-week rollover.