TODAY | June 27, 2013
>>> we're back now. 7:43. with a problem you may have experienced at some point. getting totally lost because you relied on a gps device. nbc's tom costello has been looking into this to figure it out. tom, good morning to you.
>> reporter: hey, matt. why is it you can have two or three or four different gps devices and they tell you five different ways to get to the same location or may not find it at all? they are performing hundreds of calculations and there may not be one single right answer. often they are loaded with different mapping software . what if the maps are wrong? it was only supposed to be a day trip into california's death valley for donna cooper, her daughter, and a friend.
>> 5.1 miles.
>> reporter: relying on the gps they nick named nell. when they tried to return home it was soon clear nell was lost.
>> recalculating. recalculating.
>> the road was pretty much like this.
>> reporter: for 60 miles, she says, they were directed to roads that no longer exist.
>> around and around and around. we just kept getting further and further and further into death valley .
>> reporter: the temperature outside, 128 degrees.
>> please drive to highlighted route.
>> reporter: fearing for their lives, they left messages on their car, then broke into a shelter to get out of the heat. while rarely as dramatic, almost everyone has their own story of being led astray by their gps .
>> probably about 80% of the time it's correct but 20% of the time it takes you down roads that don't go where you need to go.
>> many times i just couldn't get home without the gps .
>> reporter: it turns out different gps units use different map software. often created by teams who drive around in cars loaded with mapping gadgets but not all units are up to date.
>> do you have everybody out?
>> reporter: near boston a woman with two kids claims she followed her gps instructions on to railroad tracks . they got out just before the train crushed their car.
>> okay. everybody is okay?
>> reporter: in some remote areas the gps may be relying on really old government maps.
>> it is absolutely possible there is data in there 10, 20, 30, 40 years old and would still show up and be entirely wrong.
>> reporter: the folks who publish the michilin travel maps did their own study and found 30% of all adults use some sort of gps unit and 63% of gps users report having been led astray at least once by the gps instructions. back in death valley a helicopter rescue team found donna cooper and the kids after three days in the desert just in time.
>> people who get lost in death valley do not live. we were so very fortunate. i mean, so very fortunate.
>> reporter: we asked the gps industry to explain how this happens and it declined, but the technology, pro se , it is important to update your gps devices with the latest software. if you have a cell phone or mobile phone chances are it updates automatically. the other alternative? i know this is hard for you and me, matt, but bring a map.
>> what is that? what is that paper thing you hold in your hand?
>> yeah. i've seen people tom driving down the highway with maps on the dashboard above the steering wheel. we don't want people to do that either.
>> that is a different tom costello story, distracted driving.
>> exactly right. all right, tom. thanks very much.