Conditions:
Given a standard 1:50,00scale military map
with a declination diagram, a pencil, and a
magnetic azimuth and a grid azimuth that
must be converted.
Standards:
Converted the given magnetic azimuth to a
grid azimuth and the given grid azimuth to a
magnetic azimuth without error.
Performance Steps

1.
The northsouth lines on your
map give grid north. The needle of
your compass points to magnetic north.
Grid north and magnetic north are
usually different by a few degrees.
Neither one points straight to the
North Pole (called true north), but
you do not need to 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
mapsheet (figure C30).

Figure C30.
Declination diagram

2.
The difference between grid
north and magnetic north is called the
gridmagnetic (GM) 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 C31).

Figure C31. GM angle 
3.
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 (see figure 2)
tells you that the GM angle is 9
degrees, and it also tell you that
"to convert a magnetic azimuth to
a grid azimuth, add the GM
angle." Therefore add 9 degrees
to your compass reading. This gives
you 190 + 9 = 199. Your grid azimuth
is 199 degrees.

4.
The GM angle depends on where
you are in the world.

5.
Convert azimuths when given an
easterly GM angle (figure C32).

Figure C32.
Converting azimuths with easterly GM
angle

a.
To convert a magnetic azimuth
to a grid azimuth, add the value of
the GM angle to the magnetic azimuth.

b.
To convert a grid azimuth to a
magnetic azimuth, subtract the GM
angle from the grid azimuth.

6.
Convert azimuths when given a
westerly GM angle (figure C33).

Figure C33.
Converting azimuths with westerly GM
angle

a.
To convert a magnetic azimuth
to a grid azimuth, subtract the value
of the GM angle from the magnetic
azimuths.

b.
To convert a grid azimuth to a
magnetic azimuth, add the value of the
GM angle to the grid azimuth.

Evaluation
Preparation:
Setup:
Give the soldier a standard 1:50,000scale
military map, a piece of paper, a pencil,
and a magnetic and grid azimuth to be
converted.
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 correct grid
azimuth.





2.
Determined 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
what was done wrong and how to do it
correctly.
References


Required

Related


FM
325.26


