There have been a few dozen good responses to the post I wrote about new technologies or services that could help find people who get into trouble while traveling. See A Webware challenge: Make cell phones better lifelines.
It begins with notification. You don't send out rescue parties until you know someone is lost, and my initial proposal simply allows the alarm to be raised earlier. Several people rightly commented that it would be difficult to create a "flight plan" system that people would actually use. But I will not dismiss this idea just yet; some of the latest Web apps make data entry incredibly easy, and if itinerary information is already in a personal organizer of some sort, creating the plan and the notification schedule could become almost completely hands-off.
Still, human nature and the realities of travel being what they are, it will mostly fall to people who become lost to call for help. But how? Clearly, if there were cellular coverage in the Oregon wilderness we wouldn't be mourning the loss of James Kim today. A few people wrote that the United States, multiple competing cellular technologies were a contributor to the tragedy. If all carriers were on the same technology, money could be spent improving overall coverage instead of duplicating it in only the most profitable markets. However, extending the coverage to rural and wilderness areas would likely require government action.
There are products and technologies designed specifically to locate people who are stranded far from civilization. Emergency locator beacons are standard in airplanes, for example. They're activated only in life-threatening emergencies and send distress signals via satellite over a dedicated emergency band. See Equipped To Survive's Ultimate Personal Locator Beacon FAQ. Newer personal models are not much bigger than cell phones and have both built-in GPS and short-range locator beacons as well. These devices are expensive, however, and people who rarely leave well-traveled areas are unlikely to invest in them. One proposal involved a different economic model for emergency locators: Sell the devices for cheap but make using them very expensive. That would get the hardware into more hands and, theoretically, would not overwhelm the system with false alarms.
A few readers mentioned Verizon's Chaperone program, which allows family members to locate loved ones' cellular phones. The service will even alert you when the phone leaves a defined geographic area, a feature called "geofencing." In the case of someone who goes missing and who leaves the cellular coverage area, presumably the Chaperone program would tell its subscriber (not the person who has the phone) where the phone was last seen, without requiring him or her to jump through legal hoops to get the data. See also Sprint's Family Locator service.
There are also similar solutions for business users of the Nextel network, such as Xora [see video here]. And then there's the Web 2.0 company Mologogo, which can access GPS data from Nextel phones (and phones from the Boost consumer subbrand of Nextel) and publish that to the people you want, ranging from the world to just your family.
A few people offered an idea that seems obvious in retrospect: If cellular signals can be used to triangulate the location of a subscriber, why not set up airplanes or even blimps with cellular receivers for locating phones that stray to out-of-service areas? I believe this should be something every search-and-rescue team has access to.
See also our story on News.com: Survival and prevention tips: Share your suggestions.