Coastguard issues GPS date rollover warning

Boaters with older GPS systems will need to take action before April 6 to avoid position and time errors

The Maritime and Coastguard Agency has issued a warning to users of older GPS navigation equipment concerning a date rollover that will take place on April 6.

GPS systems store Week Numbers as a 10-bit binary number which allows for a maximum of 1024 weeks (19.7 years) before resetting to 0.

At that point, stand-alone GPS receivers and systems using GPS chips, could produce data that is 19.7 years either in the past or future, therefore generating errors in both the GPS position and time.

As this system was first rolled out in 1980 there has already been one rollover, meaning manufacturers should be aware of the situation.

However the organisation says that equipment older than 10 years or that has had no firmware updates could be at risk. Relatively new equipment and units with firmware that is regularly updated are at lower risk.

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The MCA has published the following ‘Actions to take’:

  1. Ensure all recent firmware updates are completed.
  2. Check with your GPS manufacturer for further information on GPS-dependent equipment and identify what action, if any is, required by the operator.
  3. Identify what effect this could have on your current operations, PNT (position, navigation and timing) solutions and potential issues if failure occurred.
  4. Operators of such equipment should monitor and, wherever possible, verify their equipment for any errors.

Luke Hallett, Radio Spectrum Policy Co-ordinator for the Maritime & Coastguard Agency, said: “If your GPS is more than 10 years old or it’s had no firmware updates then you’re definitely at higher risk of you GPS not working from 6 April.

“If your GPS falls into either of those categories you need to check with the manufacturer before April 6, otherwise time and position data used for navigation could become inaccurate. It’s important that GPS users check their systems as soon as possible to ensure that they won’t be affected by the impending rollover.”


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