Cell Phone Friend or Foe


Facts about cell phones

  • Cell phones use power when you are not using them.
  • Cell phones use a lot of power to turn on the screen.
  • Texting and Social Media use a lot of power because the screen is on.
  • Using the phone to navigate uses a lot of power.
  • The GPS on a smart phone is not as accurate as a wilderness GPS.
  • 911 operators can only get your “rough” network location.
  • In the wilderness, the accuracy of the location is very low, and almost useless.
  • We can sometimes locate you with the GPS on your smart phone.
  • We cannot locate you with the phone when it is out of range or out of power.

A cell phone can be a valuable resource in a back country emergency. If the area has cell
service, the phone can be used for two-way communication with rescuers. It also can be used
by rescuers to help locate the caller. Back country travelers, however, should never depend
on cell phones as a primary navigation and communication device because of limited
reception in the back country. Cell phones also have relatively short battery life and are not
designed for extreme environments.

Keeping these precautions in mind, we offer the following tips to maximize the value of the cell phone as a rescue resource:

  • The most critical factor in using a cell phone in the back country is cell coverage. Cell
    phones send data through radio frequencies that require line-of-sight between the phone and the
    cell tower. Many, if not most, wilderness areas do not have good cell coverage. If your phone shows
    that you don’t have service, don’t give up immediately, however. Often reception can be improved
    by moving to higher ground or out of areas where heavy forest canopy or canyon walls block
    reception. Cloud cover can also affect reception.


  • Even when reception is inadequate for voice communications, the connection may be adequate for a
    text message. Text messages use far less battery power than voice calls and are ideal for simple
    messages. 911 service is not yet equipped to accept text messages, but you can text your
    emergency to a reliable friend (or two) with instructions to call 911. Send your friend a description of
    your emergency and your phone number. Rescuers will then be able to communicate with you by
    text message. If a text message does not go through immediately, hold the phone higher and try
    again. Move to higher ground and repeat if messages are not sent. Keep trying from different
    locations until your message is sent or it is clear that you cannot establish a connection.


  • Newer phones are equipped with a GPS chip, which can determine the phone’s location by
    connecting to the GPS satellites. If the phone has a GPS application installed, the user can extract
    the GPS data directly. The user can then apply that information to help them determine their
    location. However this use of the cell phone is very energy intensive and can drain the units
    battery quite quickly. Once the cell phone has drained its battery the GPS function along with any other
    tracking or rescuing function will no longer be available. Never depend solely on a cell phone for
    trip navigation.


  • When a caller connects with 911, the 911 system can often extract the GPS coordinates from the
    phone. This happens automatically, even when GPS is turned off, and does not require a GPS
    application to be installed on the phone. In cases where GPS coordinates cannot be retrieved from
    the phone (older phones and networks), the service provider can work with law enforcement officials
    to locate the phone using other methods, such as triangulation from cell towers. These methods
    typically are less accurate than a GPS location. Once location information is obtained, it is
    communicated to the police and provided to rescuers to help locate the subject. This sort of
    information about a subject’s location has become increasingly common and valuable in our rescue


  • The accuracy of the coordinates from the phone’s GPS depends on several factors, especially the
    number of satellites to which the GPS has connected. These connections take time and can be lost
    when the phone is moved. A 911 call may not extract data with the same accuracy as could be
    obtained from a GPS application that has been running on the phone for a longer period. A second
    911 call often extracts more accurate coordinates from the phone.


  • Many smart phones can run mapping applications that take advantage of the GPS functions in the
    phone. These applications allow the user to see their location on a topographic map or satellite
    image of their area. This information can be especially useful for backcountry navigation.
    Downloading maps, however, is a battery hog and so is extended use of the phone’s GPS. Ideally,
    the user should download maps and store them on the phone before leaving home. Better yet, use a
    standalone GPS unit with maps installed and carry extra batteries. Always rely first on the simple
    technology of a map and compass. Use a GPS device or a smart phone to aid in navigation, but
    understand that they become worthless once the battery dies.


  • Some other smart phone applications also use the phone’s GPS. This is sometimes called
    geotagging. For example, Facebook and others includes a function that allows users to track their travels for
    friends. The information posted by Facebook, however, is not precise enough to significantly aid
    search efforts. Such postings require an internet connection and consume significant battery power
    that should be conserved for critical communications.

As suggested by many of the above tips, battery power is critical.
  1. Be sure your battery is charged before you leave home. Then leave the phone off
    until you need it.
  2. Keep the phone warm by carrying it in an inner pocket. Warm a cold phone by
    holding it in your armpit next to the skin for 15 minutes. Cell phone batteries are
    like hypothermia patients; don’t conclude they are dead until they are warm and
  3. Phones consume considerable energy trying to make the initial connection. When
    you don’t have service, turn the phone off until you have moved to a better
  4. While in the backcountry don’t use the phone for entertainment or casual
    communications. Instead save your battery by enjoying your surroundings and
    talking with your fellow adventurers.
  5. Consider carrying an auxiliary battery with a full charge, and keep it in reserve for
    emergency use.