A fleet of GPS satellites broadcasted the wrong time for several hours last week thanks to a software mistake. It caused problems with telecommunications and digital radio, but could have been much more serious.

The problem appears to have started during the decommissioning process of a US Air Force satellite named SVN 23. It seems that this led to 15 satellites, which broadcast a coordinated time signal, to cause a universal time signal error of 13 microseconds.

The bug was fixed after a few hours. However Chronos Technology, which provides timing services for telecommunication, energy and financial market networks, says some customers were affected for up to two days. One client alone had nearly 2,500 system alarms triggered.

Meanwhile digital radio broadcasts in the United Kingdom suffered some outages. In both cases, the problem is that the precise timing is needed to control the way flows of data are broken up, delivered and reassembled.

According to Chronos, many companies were able to get through the problems because they used a back-up synchronization such as an atomic clock. This might not have been sufficient had the GPS error gone on much longer.