How to use the altimeter

The altimeter provide only one simple piece of information, the elevation. By monitoring the elevation and checking it against the topographic map, wilderness travelers can keep track of their progress and pinpoint their geographical location. Altimeters are of course to no help where there is little or no change in elevation. However, in mountainous terrain, it can be of great navigation help.


How does an altimeter work?

But how can an altimeter measure elevation? Air pressure decreases at a predictable rate with increasing altitude so an altimeter shows air pressure on a scale calibrated in feet or meters above or below the sea level. Therefore is an altimeter basically a modified barometer.


Accuracy depends on the weather

If air pressure depends on weather then also the accuracy of an altimeter depends on the weather. Changes in weather could easily decrease the precision more then 10 times for even high quality altimeters. Even during apparently stable weather conditions your indicated elevation may change.


Calibrate as often as possible

Nevertheless an altimeter can be of good navigation help if you use it right. Don't trust the instrument until you first set it at a known elevation. Then check the reading whenever you reach another point of known elevation so you can reset it if necessary. Recommended that altimeters are calibrated as often as possible in order to achieve the highest altitude accuracy reading.

Some of the more high performance portable GPS units not only have an integrated electronic compass but also an altimeter. Allowing you to have all your electronic navigation tools in one unit.

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