Orienting Maps (Lat/Lon)

Navigation and field mapping skills will help you know where you are, where you are going, how you are going to get there, how long it will take, and when you will get back. Even in rough terrain and poor visibility these skills can help you get to your destination by choosing the best route with the least resistance. Always have a compass and map when navigating, do not rely only on a GPS receiver. Field mapping is also important because operational decisions are made based on the information on the field maps.

This chapter builds on what you learned in all the other chapters. It starts with how to orient a map. Then it outlines the steps on how to measure a bearing on a map, plot points using latitude/longitude and UTM coordinates, estimate your own position location, and estimate unknown position locations. Next it discusses the different methods for estimating distance on the ground, such as pacing. Finally, it addresses field mapping and note taking.

Orienting the map to true north is key to navigating successfully. Orienting a map also gives you a general idea of your own location on the map. This section describes two methods to orient a map: topographical orientation and compass orientation.

Orienting a Map with Topographical Features

Steps to orient a map using topographical features.

  1. Find your approximate location on the map
  2. Select two prominent topographical features or landmarks that are visible to you and shown on the map.
  3. Turn the map until the features on the map are in proper relation to the actual features in the field. The map is now oriented.

navigation_pms6-1

 

Orienting a Map with a Compass

If there are limited topographical features for orienting a map, then orient the map with a compass.However, adjust the compass for declination before using it with a map. One method for orienting a map with a compass is described below.

Steps to orient a map using a compass.

  1. Adjust the compass for declination as appropriate. Make sure there is no local magnetic attraction.
  2. Rotate the compass housing so north or 360 degrees is at the index line or direction of travel line on the compass.
  3. Place one side of the compass base plate along the right or left hand edge of the map. The direction-of-travel line must be toward the top of the map.
  4. Carefully rotate the map and compass together until the needle is aligned with orienting arrow. The map and compass are now oriented.

navigation_pms6-2

 

[Continue to Measuring Bearing on a Map]

**Information adapted from the National Interagency
Incident Management System Basic Land Navigation
Manual, PMS 475 dated June 2007.