EUGENE, Ore. - Handheld GPS systems, car GPS units, MapQuest, Google Maps - electronic navigation systems are everywhere but how much should you rely on them?

GPS mishaps can happen because they don't factor in all those constant changes on the road.

"It's taken me on dead-end streets and construction zones," said John Miller with Lane County Search and Rescue.

Miller said they get a handful of calls each year from folks who get lost while following directions on their GPS device.

"The map doesn't take the third dimension into account," he said. "They don't consider weather, road maintenance, climate conditions or seasonality."

I decided to see where a computer mapping program would lead me.

Miller said most folks get lost going to the coast or the mountains, so I typed in Diamond Lake to Crescent, Oregon, using Google Maps.

The program said the trip would take about an hour but if you drive the route, you would actually cross a 7,000-foot peak. In the winter, snow could get you stuck.

Miller said while all new technology can be useful, you shouldn't rely on it completely.

"The skill of learning how to take care of yourself, deal with the situations that you're putting yourself into - those types of things, technology will never take their place," he said.

To be fair, I talked with folks at Joe's Sports & Outdoors and they said GPS systems are hot sellers and they've had almost no complaints. Also, some cell phone GPS systems do update information like traffic accidents and weather.