GPS Can Fail You

How GPS Works in Brief

GPS, short for Global Positioning Systems, are now a very common navigational aid used by hikers, hunters, and outdoorsmen of all types. The GPS system provides satellite signals that can be processed by GPS receivers to calculate our position, elevation, and time.

Many do not realize that the GPS satellite navigation system is controlled by the US Department of Defense. The GPS Operational Constellation is composed of at least twenty-four GPS satellites that orbit the earth every 12-hours and are positioned so that at any location on the earth between five and eight satellites are available for locative uses.

To discover your location on the surface of the earth the GPS receiver must be able to locate four or more satellites in the sky above you. As your GPS unit receives data it calculates the distances between your location and these satellites and then uses this information for the trilateration (similar to triangulation) of your position on the earths surface.

GPS Should Work in Theory

GPS Unit

Simply by carrying a handheld GPS unit we can conveniently obtain our current latitude and longitude, approximate elevation above sea level, and accurate time of day. We can also record the positions of where we have been and obtain the bearing and distance to places we want to go. A boon to those of us who travel outdoors and especially in wilderness areas.

Now the GPS system is all well and good in theory. Navigation with GPS works so well we often come to rely upon it. This can lead to serious problems – because when people begin to rely totally upon their Global Positioning Systems for information about where they are and how to get places if something goes awry they could be setting themselves up to become lost.

How GPS Can Fail

GPS Satellite System

Imagine for a moment you are happily using your GPS to navigate back to your vehicle through unfamiliar territory. You have previously entered the coordinates of the destination vehicle into your GPS unit. Simply by turning on your GPS unit and waiting a few minutes to get a fix on the satellites above you, you can find the bearing and distance you need to travel. As you progress you occassionaly take a new reading and in that way continue on the correct path.

Suddenly your GPS unit falls from your backpack into a swift moving river and is lost forever. Or it smashes into a dozen pieces when you trip and fall. Or a state of war is declared and the Department of Defense blocks the Geographic Positioning System or alters it in a way to make it totally inaccurate.

GPS Map and Compass

If you mindlessly rely upon your GPS system to tell you where you are and where you are going you may very well find yourself lost in the wilderness.

Ways GPS Can Fail You

Some of the ways in which Global Positioning Systems can fail are:

Solar flares can degrade GPS reception.
Geomagnetic storms can adversly effect the Global Positioning System.
Man-made interference from intentional jamming.
Malfunctioning electronic devices nearby.
The military may suddenly and without warning employ selective availability to its GPS Satellite array in time of war or crisis.
Thick vegetation may prevent a clear view for the minimum number of satellites needed for trilateration calculations.
Mountainous regions may prevent you from viewing enough GPS satellites.
Your GPS Unit may malfunction.
You may loose your GPS unit due to misplacement, falling into water etc.
Your GPS unit may become damaged from a fall etc.
You may be using an incorrect coordinate system relative to your maps.
The batteries in your GPS unit may run down, especialy if you are out in the bush for longer than you planned.

There are a host of additional causes for GPS units to fail or give bad positional information.

You Need a Backup to GPS

Successful survivors plan ahead and take into account problems that may occur with the survival gear and equipment they rely upon. For the most important elements of survival you should have redundant means so that should one method fail you can still rely upon another to accomplish the same task.

The fact is you need a fall back plan in case of a Global Positioning system failure or malfunction.

GPS Compass Map

The big three navigational aids when traveling through the wilderness are GPS, map, and compass. Carry all three. As a backup positional method to your GPS there is nothing better the proven standby of map and compass, combined with the ability to use them.

Stay Aware of Where You Are

When using a Global Positioning System while traveling in unfamiliar areas be sure to stay mindful of the area around you. Note landmarks and compare them to where you think you are on the map. Compare these landmarks and your direction of travel to compass readings. This double checking of the locative information obtained from your GPS unit could be crucial to your very survival.