Simple Update. Done While Other Mods are in Process.


What is the GPS Week Number Rollover (WNRO) Event?

The Global Positioning System (GPS) rollover event happens every 1024 weeks or about 19.6 years. The Flight Management System’s (FMS) GPS broadcasts a date, including a weekly counter stored in the software using 10 binary digits. The range for this software variable is 0-1023, so after the internal value rolls over to zero, software that does not anticipate the rollover may stop working or potentially display a 20-40 years old date. The week counter in the Universal Avionics System Corporation’s (UASC) SBAS FMS will roll over to zero on May 31, 2025. The result is a grounded aircraft.

Avoiding this situation is a simple fix that can be done while your aircraft having other cabin or flight deck modifications including:

  • Cockpit Voice Recorder upgrades

  • Flight Displays


  • AHRS Replacement

  • ADS-B Out, Flight Following

  • Comm/Nav/Pulse

  • PAX Briefing Systems

  • Onboard Connectivity and Cabin Routers

  • USB power and charging ports

  • iPad mounts, and more

Implementing a Service Bulletin on your Universal SBAS FMS corrects the issue, ensures the proper date will be displayed and keeps your aircraft flying.

We are Canada’s premier independent avionics integrator and support center and will work with you to update your SBAS FMS.

Be GPS Week Number Rollover (WNRO) Event Ready

Contact one of our friendly, knowledgeable avionics sales experts