BUILDING TRUST. SHAPING SAFETY
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Technical Notices

Global Positioning System (GPS) Week Rollover Event

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On 6 April 2019, how Global Positioning System (GPS) devices display time may be affected by a change in the GPS navigation message signals.

The way GPS broadcasts time and date information involves a 10-bit week number (0-1,023), which resets or “rolls over” every 1,024 weeks or approximately 19.6 years. The next week number rollover will occur on 6 April 2019.

The 2019 GPS Week Number Rollover could have a potential effect upon GPS receivers (including GPS sensors and GPS receivers embedded within multifunction displays, chart-plotting products, AIS receivers and VHF radios) and any of their features dependent on date/time information.

Owners of ships fitted with equipment reliant on GPS signals, should:

  • Ensure the equipment’s firmware is up to date
  • Contact the manufacturer to ensure the equipment will not be adversely affected by this event.
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