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Conditions: Given a standard 1:50,000 scale military map with a declination diagram, a pencil, and magnetic and grid azimuths that must be converted.
Standards: Convert the given magnetic azimuth to a grid azimuth and the given grid azimuth to a magnetic azimuth without error.
1. The North-South lines on your map give grid north. The needle of your compass points to magnetic north. Grid north and magnetic north usually differ by a few
degrees. Neither points straight to the North Pole (called true North). However, you need not know true North to keep from getting lost in a combat area. The difference
in degrees for every map is shown on the bottom of map sheet (Figure 071-329-1009-1).
Figure 1. Declination diagram.
2. The difference between grid north and magnetic north is called the grid-magnetic (G-M) angle. The diagram at the bottom of the map tells you how to change
grid azimuths to magnetic azimuths and magnetic azimuths to grid azimuths (Figure 071-329-1009-2). For example, you aim your compass at a distant point. The
compass reading you get is 190 degrees, the magnetic azimuth. The diagram on your map (Figure 071-329-1009-2) tells you that the G-M angle is 9 degrees, and it
also tells you that "to convert a magnetic azimuth to a grid azimuth, add the G-M angle." Therefore add 9 degrees to your compass reading. This gives you
190+9=199. Your grid azimuth is 199 degrees.
Figure 2. G-M angle.
3. The G-M angle depends on where you are in the world. Convert azimuths when given an easterly G-M angle (Figure 071-329-1009-3).
Figure 3. Converting azimuths with easterly G-M angle.
a. To convert a magnetic azimuth to a grid azimuth, add the value of the G-M angle to the magnetic azimuth.
b. To convert a grid azimuth to a magnetic azimuth, subtract the G-M angle from the grid azimuth.
4. Convert azimuths when given a westerly G-M angle (Figure 071-329-1009-4).
Figure 4. Converting azimuths with westerly G-M angle.
a. To convert a magnetic azimuth to a grid azimuth, subtract the value of the G-M angle from the magnetic azimuths.
b. To convert a grid azimuth to a magnetic azimuth, add the value of the G-M angle to the grid azimuth.
Evaluation Preparation: SETUP: Give the Soldier a standard 1:50,000 scale military map, a piece of paper, a pencil, and a magnetic and grid azimuth to convert.
BRIEF SOLDIER: Tell the Soldier to convert the magnetic azimuth to a grid azimuth and the grid azimuth to a magnetic azimuth.
Performance Measures GO NO-GO
1. Determined the correct grid azimuth. —— ——
2. Determined the correct magnetic azimuth. —— ——
Evaluation Guidance: Score the Soldier GO if all performance measures are passed. Score the Soldier NO-GO if any performance measure is failed. If the Soldier
scores NO-GO, show the Soldier what was done wrong and how to do it correctly.
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