Eutelsat OneWeb satellite internet went down for 48 hours because developers forgot about an extra day in 2024

The developers of the Eutelsat OneWeb satellite Internet network forgot to take into account the 366th day in 2024 in navigation programs, which led to a network failure until the error was corrected. Last year was a leap year, which was a surprise for the system launched in 2023, which had 365 days. During the transition to the new year, the navigation stopped functioning. It took two days to fix the problem, during which competitor Starlink was unable to provide service.

Image source: NASA

The failure in the Eutelsat OneWeb system is akin to the so-called Year 2000 problem. Historically, programs used two digits to record the year, and changing from 1999 to 2000 without proper accounting would return programs to 1900. This could affect the safety of work in a number of critical areas, including navigation, and the “Problem 2000” had to be urgently fixed by many teams of programmers. Accounting for one extra day in a leap year shouldn’t have been a problem, but as it turned out, it was.

Fortunately, the error was only in the software of the ground segment of the network and did not affect the satellites, of which Eutelsat OneWeb currently has over 630 in orbit. The GPS – global positioning system relies on timing, and a failure in determining the time could force the satellites to maneuver with unpredictable results. By January 1, the network was 80% restored, and full functionality returned on January 2.

A company spokesperson told the source: “We can confirm that the outage was caused by a leap year issue related to the 366th day of 2024, which affected the calculation of the GPS offset relative to UTC.”

The problem is solved, but a residue remains. Eutelsat joined the SpaceRISE consortium. With its participation, among other things, the multi-billion dollar budget of the European Union will be used to create a new European broadband network IRIS2 by 2030.