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Cell phones in the backcountry

Greg Foley
Grand County Search and Rescue
This viewshed map near Lake Granby shows areas of interest where coverage from the Grouse Tower near Parshall and the Berthoud tower overlap. A cell phone hitting both of these towers could only be located in the lime green overlap areas.
Greg Foley/For Sky-Hi News |

Cell phones have changed the way search and rescue gets notified of backcountry emergencies. Used to be someone would have to hike out to the trailhead, get in their car and then drive to the nearest landline phone. Now, with most carrying their cell phone with them beyond the trailhead, cell phone 911 notifications are extremely common. In some areas, including Grand County, you now have the ability to send a text to 911.

There are a few things you need to know before counting on a cell phone for your primary emergency rescue plan.

A cell phone cannot provide warmth, water, food, shelter or first aid. Your phone should be a backup to standard backcountry precautions. Even if you are able to place an emergency call or text, it takes time for SAR volunteers to mobilize and respond. If you get into serious trouble you may not be physically able to use your phone. That said, your cell phone can be a valuable asset.



Make sure that you have plenty of battery when you need it. If you are traveling in the backcountry either put your phone in airplane mode, power saving mode or turn it off to conserve battery. Keep the location service off until you need it. Searching for cell service, wi-fi or satellites burns battery power. Keep your phone in a warm place, not an outside pocket.

If you are able to call or text 911 there is a good chance that the dispatcher will get an accurate GPS location, but this depends on a lot of factors and is not guaranteed. Last weekend, a driver called 911 after midnight when he went off the road, injuring himself. He could not describe his location, and dispatch was unable to get a good location because he was only hitting on one tower. There was no telling which road or highway he was driving.



In a situation like this we can also employ cell phone forensics from the Air Force Rescue Coordination Center. They may be able to provide a “viewshed” which shows, on a map, the possible ground locations where a cell phone has been at a particular time. If a phone is hitting two or more towers the viewshed map will detail those areas where cell service overlaps, providing clues to areas of interest for search efforts. The cell tower data may also detail the distance and general direction from the tower.

The AFRCC forensics team viewshed map indicated that our driver was somewhere on Berthoud. Turned out he went off US 40 at the bottom switchback on the west side.

In many areas there is limited or no service. If there is no service try changing your location, ridgetops and summits usually have a better “view” of cell towers. When there is limited service, you may be able to send a text, even if you can’t make a call. It’s best to keep the message simple and short. If you can, include an accurate location description, GPS coordinates are best.

Do you know how to get GPS coordinates from your phone? GPS coordinates, which describe a unique location, will enable search and rescue to come directly to you.

Coordinates are a pair of numbers separated by a coma that give your location in latitude (north) and longitude (west). The coordinates for the top of Byers Peak look like this: 39.8643620, 105.9472372

Here is what I know works to get coordinates from your phone. There are undoubtedly other methods.

If you have an iPhone you can find your coordinates with the Compass app. Of course your location service has to be turned on. Better yet, download a free GPS coordinate app that allows you to cut and paste the coordinates into a text or email.

With an Android phone, and if you have cell service, you can get the coordinates from the info for a dropped pin in Google Maps. You can share the map location by text. Once again, Google Maps only works when you have good cell service. The work around is to download a dedicated GPS coordinate app which allows you share the coordinates by text or cut and paste the coordinates into a text.

Take a few minutes and download a GPS app today so you will have the ability to determine your location coordinates should you have the need. Make sure you practice with it a few times so the process is streamlined for emergency use.

And don’t forget to tell someone where you are going and when you plan to return, just in case your phone doesn’t work.


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