Are you ready to party like it’s 1999?!

Reminiscent of the Y2K scare almost 20 years ago, the U.S. global position system (GPS) satellites will be encountering a ‘week number rollover’ this Saturday Apr 6. This rollover will set back the current GPS systems to 1999, which could be cause for some interesting issues.

When we think of GPS, the handy little cell phone application that helps us get wherever we need to go, might be the first thing that comes to mind. However, GPS signals play a much larger part in our everyday lives that we don’t even notice.  GPS signals are utilized in almost every industry. They can be used to map forests, help farmers harvest their fields, and navigate airplanes on the ground or in the air. GPS systems are used in military applications and by emergency crews to locate people in need of assistance.

Orbiting above our heads, 12,000 miles up, are 24 satellites. Each satellite is broadcasting the time back to Earth. But not just any time… atomically accurate time. In addition to being able to pinpoint your precise location anywhere on the planet at any time, the GPS system contains an internal tracking system for the number of weeks it has been in orbit. Because the GPS computers only use a 10-bit system, the counter resets to zero every 1,024 weeks (which is equivalent to 19.7 years).  Each 19.7-year period is known as an ‘epoch’ in GPS terms.

GPS signals began their week number count on Jan 6, 1980. The system hit its first 1,024-week rollover on Aug 21, 1999. And the next is set to place this Saturday Apr 6 at 23:59:42 UTC (6:59 p.m. CST).

So, what does this mean for the average person? Hopefully, not much. Luckily, officials at the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency have warned critical infrastructure operators in communications, transportation, power grid, finance and other fields to ensure that their GPS receivers can handle the resetting of the counters this week. Therefore, most issues should be pretty well planned for. However, a nanosecond error in GPS time is equal to 1-foot of position error. That means the smallest hiccup or delay from the top could have some pretty significant issues once it trickles down to our own personal GPS signals.

Some devices, if older than 10 years old, could suddenly reset themselves to 19.7 years ago. However, newer devices and network-connected devices should have received firmware updates to prevent this from happening. Since this is the second time the week rollover clock has reset, most companies have a plan in place.

It’s hard to say what could be the outcome of this epoch ending, but keep one thing in mind – it’s probably best not to rely 100% on your GPS signal this Saturday around 7 p.m. You really don’t want to end up turning left too soon and arriving at the wrong ‘final destination’.