One wireless analyst, Jack Gold at J. Gold Associates, said the GAO report might be received by the public as more serious than it is. "Obviously GPS is something people rely upon, but we have to be careful we don't overstate the case," he said.

GPS satellites would not fall from the sky, but their radio transponders could fail and it might take 18 months to prepare and launch a replacement, Gold said. When the transponders in the satellites fail is also hard to predict.

Gold said average drivers with GPS devices could probably rely effectively upon only four GPS satellites, but the U.S. military needs 24 or more to make precise calculations. The GAO report is probably more of an alarm to remind people of the importance of GPS, he reasoned.

"It's not just the U.S. that relies on GPS," he noted. "It's the entire world."