For one brief moment, outdoor enthusiasts spoiled by the advent of computer technology may be catapulted back to the Stone Age.
They may be forced to use . . . a map.A Y2K-related glitch could cause a temporary malfunction of the Global Positioning System on midnight Saturday.
Federal officials are alerting motorists, boaters, airplane pilots -- and particularly hikers and backpackers -- who rely on the satellite-based system to determine their locations.
Cars with disabled GPS systems are unlikely to cause their drivers to become lost, assuming there's a map in the glove compartment. The same can be said for boats on Lake Powell or other Utah lakes where shore is never far away.
But it could be a different story for overnight campers who, for example, hike into the Utah desert on Saturday night and wake Sunday to find their portable GPS system no longer works correctly. Or worse, they may think it is working when in fact it is giving false readings.
"If you're out on the desert and you're not paying too much attention to nautical navigation, there could be a problem," said Steve King, spokesman for the U.S. Department of the Interior. "If we lose just one person it's one person too many.
"We want the hikers and campers to know about this. All they need to do is check with their manufacturer."
Small-plane pilots who rely on GPS generally don't fly in the early morning hours. But they could run into problems if they land in a remote location, stay overnight and can't get their GPS receivers to work Sunday.
The problem is that some GPS receivers, primarily older ones, may not interpret correctly the "end-of-the-week rollover" beginning Sunday, as well as the year 2000 calendar change on Jan. 1.
The rollover occurs once about every 20 years. The GPS calculates time by counting the number of weeks since Jan. 6, 1980, up to a maximum of 1,023 weeks. At midnight Saturday, the counter will roll over to week zero and officials fear that may be interpreted by some GPS receivers as an invalid date.
Scott Haywood, spokesman for the federal Navigation Information Service, said the disruption should be minimal. Some GPS receivers may just take a little longer to lock onto a satellite and establish location.
"It's nothing real major," Haywood said. "They're not telling people not to go anywhere."
King said there is a chance a glitch in the GPS could occur 36 hours earlier at roughly noon Friday. That is when the Air Force will upgrade the almanac used by the GPS.
Officials suggest owners of GPS receivers check with the manufacturer to find out if the receiver is compliant with the rollover and the Y2K bug.
A list of receiver manufacturers and their contact numbers is available by calling the government's Y2K hotline at 1-888-USA-4Y2K, 7 a.m.-6 p.m. MDT. The information also is available on the U.S. Coast Guard's Web site at www.navcen.uscg.mil/gps/geninfo/y2k/default.htm.
The manufacturer will need to know the receiver's model, serial number and the firmware version or release date displayed on the receiver's startup screen.
The AAA is advising its members to contact manufacturers if they are concerned a GPS receiver in their motor vehicle may malfunction.