Two Australian tourists in New Zealand found out the hard way that you can't always rely on GPS to give you the best route. The visitors rented a car from Avis, which comes with a GPS system, plugged in their destination and drove where the gadget told them to drive.

The system guided them through a ten-hour, death-defying journey into hell: through rivers, fog and perilous and narrow mountain passes terminating at a locked-gate dead end high in the mountains.In my experience, GPS is generally much more reliable than MapQuest or Yahoo Maps. Don't get me wrong: I love map services and really, really love my GPS. I don't know how anyone got anywhere before these resources became available. But in all cases, these computer-aided navigation systems lack something very important: Human common sense.

Computers know where the roads are, and, given a starting point and a destination, will do a pretty good job of getting you there using the roads they know about.

Drivers can learn something here from the world of aviation. When pilots are trained in flight planning, they are taught how to use aeronautical charts, flight computers, FAA-published information and other resources to come up with a detailed flight plan. After doing so, they are trained in the art of how to look carefully at the plan and determine if it "passes the test of reasonableness." In other words, apply human common sense to the plan.

Whenever you use GPS or online maps and direction sites, take a few minutes to look at the plan. Does it make sense? Computers and satellites are nice, but use the wetware between your ears to check what they're telling you before you go.