GPS-SPS users should check systems

Maritime users of the Global Positioning System Standard Positioning Service (GPS-SPS) are urged to check their systems ahead of the counter roll over on April 6. Some outdated GPS receiver systems may cease to function properly - with potential impacts on navigation. The roll over occurs because the GPS system transmits time to GPS receivers using a format of time and weeks and can only count 1,023 weeks. The previous roll over was in August 1999. When the GPS system reaches week 1024, the system will revert back to week zero. If a GPS receiver is outdated or not properly updated, it will revert to zero on April 6. Internal clocks in these GPS receivers will experience a lack of reference and may give wrong times and positions or even lock up permanently. The International Marine Organization (IMO) has issued a safety of navigation circular SN.1/Circ.182/Add.1 warning maritime users to take action for the roll over. (Source: IMO 04/02/19)