GPS “Week Number” Rollover
On 6 April 2019, the “week number” broadcasted by GPS satellites will be reset to zero. Some panel mounted GPS navigation systems and portable units require a software update to ensure proper functionality.
Many GPS receivers are prepared for the rollover and will continue to work without problems. Others need a firmware update so that they don't suddenly behave as if they've made a leap back to 21 Aug 1999.
In order to mitigate any safety risk related to the GPS week rollover, EASA recommends taking the following proactive measures:
Ensure that the latest software update is installed on potentially affected GPS receiver(s)
Request information from the GPS receiver manufacturer regarding its robustness against the GPS week rollover
If possible, perform tests that simulate the GPS week rollover, e.g. using a GPS simulator