Though few instances are quite so outrageous as the Grand Canyon fiasco, false alerts are becoming commonplace. In 2010, there was a rash of rescue calls in Grand Teton National Park, with hikers asking for help down the mountain. One asked that hot chocolate be flown in.

Last October in Yosemite, several hikers on the Cables route on Half Dome pushed on in the face of a gathering lightning storm. On the summit, hypothermic, they called for a helicopter rescue, only to be told that the rangers couldn’t fly in such weather. “I was freaking out and thought I wasn’t going to make it,” one of the stranded men later said. The next day, 20 hikers on Half Dome called 911 to ask for a rescue in similar conditions.

In some European countries, inexpensive rescue insurance covers the costs of all rescues, while in others, those rescued must pay for the help, especially when “victims” are thought to have been negligent or to have cried wolf. But in the United States, charging hikers or boaters for unnecessary rescues is an option seldom pursued. “We don’t want people not to call for a rescue because they think they can’t afford it. Then they’re likely to get into deeper trouble and trigger a more dangerous rescue,” says Jeff Sparhawk, public information officer for the Rocky Mountain Rescue Group, a search-and-rescue team based in Boulder, Colo.

Despite his cynicism about “yuppie 911’s,” Mr. Scharper sees a silver lining. “P.L.B.’s have saved a lot of lives,” he says. “And as the technology develops, the problem will partly solve itself. Instead of a ‘911 hangup’ ”— a beeping distress signal attached to GPS coordinates — “we’ll be able to text back and forth. We’ll be able to talk a lost hiker back to safety without going out to get him, or putting any rescuers at risk.”