​​​​​​​Screwed In A Millisecond

The world economy runs on the shockingly vulnerable GPS network. It needs a backup plan

- Paul Tullis

Duke Buckner was enjoying his breakfast at the Renaissance Tel Aviv Hotel, looking out on the city marina, on the day that time stuttered. Buckner oversees marketing and business development for Microsemi Corp., an American communications and defense contractor, and he gets a copy of emailed error reports for its equipment. It’s rare to get more than one in a given day. But on the morning of Jan. 26, 2016, they flooded his inbox. He forgot about breakfast.

The complaints had to do with Microsemi’s timing receivers for the Global Positioning System, the ubiquitous satellite navigation technology that was built for the U.S. military and has found its way into all our pockets. GPS isn’t just for maps. It’s also a kind of vast, spaceborne clock. Computers all over Earth use it to determine what time it is, down to billionths of a second. When there’s the slightest disagreement among those computers, things fall apart.

Microsemi’s timing receivers were frantically issuing error messages because of just such a discrepancy. “In normal operation, these things don’t generate alarms for years,” Buckner says. “So when one goes offa lot of times, people don’t know what to do.” Over the next 11 hours, cellphone towers lost their connections, U.S. police and fire stations reported communications errors, BBC radio signals were interrupted, and the telescope that tracks asteroids in Earth’s orbit went offline.

The cause was a bug in the GPS network. When the U.S. Air Force, which operates the 31 satellites, decommissioned an older one and zeroed out its database values, it accidentally introduced tiny errors into the database, skewing the numbers. By the time Buckner’s inbox started blowing up, several satellites were transmitting bad timing data, running slow by 13.7 millionths of a second.