by Dom Wiseman

The Global Positioning System (GPS) system’s week counter will be reset to zero for a second time today Saturday, 6 April 2019.

There is a good reason behind the imminent disruption. The GPS system transmits time to receivers using a format of time and weeks. The system holds a maximum of 1,023 weeks and then it must reset back to week zero. Since the first start date of the GPS technology on 6 January 1980, this will be the second ever reset, following the first on 21 August 1999.

There remains the possibility that old GPS receivers may be negatively affected following the reset. Maritime authorities have advised boaters to check the operation of their Global Positioning System (GPS) receivers following the reset of the counter.

Whilst more up to date GPS receivers are unlikely to experience any issues, older receivers, which have not been updated, run the risk of malfunctioning or ceasing to function all together.

Marine authorities have concerns that older model GPS receivers will be unable to rollover and make the transition. If this is the case, then older models are likely to read week zero as August 1999 instead. The concerning consequences of this may result in incorrect times or positions feeding to receivers. It may even result in receivers being defunct.

New receivers which are fully compliant with GPS ICD-200 are not expected to experience any issues. If users have any issues or concerns, Marine authorities have advised boaters to contact the manufacturer or supplier to check the status of the receiver.

The most important aspect from the Marine authorities’ perspective, is to be aware of the potential consequences before heading out on the water this weekend. Some older GPS receivers can be potentially revived with upgrades, but many others are expected to become unusable.