Credit: Courtesy Donna Cooper
(ABC NEWS) --A clear, hot July day in 2010 seemed like the perfect opportunity for a day trip to Donna Cooper. With her daughter Gina and a visiting friend, Jenny, Cooper set out for Scotty's Castle, a museum in Death Valley.
They packed what they thought would be enough food and water for the day, along with "Nell," Cooper's seemingly trusty GPS device. An uninvited companion was the weather -- the temperature would reach 121 degrees in Death Valley that day.
After using their credit cards to buy some things at Scotty's Castle's gift shop, the women got back into Cooper's small Hyundai to head home. A sign for another park attraction, called The Racetrack, attracted them, and Cooper took a detour.
The route took them off the highway and onto dirt roads that cars larger than Cooper's have trouble navigating.
"I've recovered vehicles from the back country that look like they have been driven over a cheese grater," National Park Service District Ranger Micah Alley told "20/20."
After driving about 10 miles without seeing The Racetrack, the women turned around to head home. Finding themselves at a dirt intersection with several unmarked roads, Cooper turned onto what she thought was the road back to the highway. But after 10 miles, the highway was not in sight.
"I said, 'Well, we went the wrong way, let's put the GPS on and get back on the right road,'" Cooper recalled.
But Nell proved to be even more confused than they were, taking them farther into the desolation of Death Valley.
"It just kept saying, go this distance and take a turn, go this distance and take a turn. Make a U-turn, go here, take a turn," Cooper said.
Lost, and without cellphone service, the three women ran out of gas after about 100 miles. The temperature began to drop as night fell. Running out of water, they settled in for an uncomfortable night.
The next morning, Gina urged her mom to try the car one more time.
"I got in the car, said a prayer, turned the key, and the car started right up," Donna Cooper said. "To this day, I cannot believe it."
Back at home, Cooper's worried family called authorities. A California Highway Patrol chopper took off to start looking. Their only clue was the credit card purchase the day before at Scotty's Castle.
The three women spied a tiny patch of green, and they left their car and hiked two miles toward it. They found three trailers and a hose with dirty well water for them to drink.
As a second night fell, they wondered if they were only postponing the inevitable.
"I was like, 'I don't want to die here,'" Gina Cooper said. "'Nobody's ever going to find us.'"
The chopper pilots, Tyler Johns and Scott Steel, told "20/20" that third day was do-or-die, the difference between rescue and recovery.
They swept the sky for six hours. With their own fuel running low, they made one last pass over Saline Valley, which Johns called "the most remote part of the park."
They saw Donna Cooper's dusty Hyundai, then Gina waving a yellow blanket.
After the ordeal was over, Cooper retired "Nell."
"It just would not get off 'Home,'" Donna Cooper said. "It was just, Home, Home, Home, Home, Home."
A GPS industry source said, "It is important for drivers to keep in mind that GPS devices are to be used as navigational aids only and shouldn't be followed blindly. It is the responsibility of drivers to exercise common sense at all times when driving, including deference to posted road signs, road conditions, and other environmental factors. It is incumbent upon users to obtain and update their GPS devices with the most recent map updates to facilitate improved accuracy."