RP0505- Land Navigation
TERMINAL LEARNING OBJECTIVES
1. Given a minimum of a 1:50000 military map, a coordinate scale, protractor, paper, map and
a pencil in a field environment, perform basic map reading, per the student handout.
(RP00.05.11)
2. Given a tactical scenario (day or night), individual combat equipment, a 1:50000 military
map, paper, pen, protractor, lensatic compass, the six-digit grid coordinate of current
location, the six-digit grid coordinate of all checkpoints and a time constraint, perform land
navigation with a map and compass to navigate to all checkpoints within the time period
designated. (RP00.05.12)
ENABLING LEARNING OBJECTIVES
1. Without the aid of references, given a list, identify the purpose of a military map, per the
student handout. (RP00.05.11a).
2. Without the aid of references, given a list, identify the five basic colors on a map, per the
student handout. (RP00.05.11b).
3. Without the aid of references, given a list, identify the purpose of contour lines on a military
map, per the student handout. (RP00.05.11c).
4. Without the aid of references, given a list, identify the seven natural features, per the student
handout. (RP00.05.11d)
5. Without the aid of references, given a list, identify the man made features contained in the
legend of the map, per the student handout. (RP00.05.11e)
6. Given a military map, protractor, compass, and a set of eight-digit grid coordinates compute
a grid, magnetic and back azimuth in this sequence for two points on a map, per the student
handout. (RP00.05.11f)
7. Given a military map, protractor, compass, and a set of eight-digit grid coordinates, locate a
position on a map with a 100-meter tolerance, per the student handout. (RP00.05.11g)
8. Without the aid of references, given a list, identify the parts of a lensatic compass, per the
student handout. (RP00.05.12a).
9. Without the aid of references, given a list, identify methods used to hold a lensatic compass,
per the student handout. (RP00.05.12b.)
10. Without the aid of references, given a list, identify the methods used to orient a military map,
per the student handout. (RP00.0512c).
11. Without the aid of references, given a list, identify the methods for determining a position
when using a military map and compass, per the student handout. (RP00.05.12d)
12. Given a military map, a lensatic compass, and a minimum of a eight digit grid coordinate,
locate specific points on the land navigation course, per the student handout. (RP00.05.12e)
1. THE MAP
Purpose - the purpose of a map is to provide information on the existence, the location, and the distance between ground features.
Definition - a geographic representation of the earth’s surface drawn to scale as seen from above.
- Shows us what an area actually looks like without being there
- A clear and handy reference tool
Characteristics of a Map
- Designed to show us common information
- Location of ground objects
- Populated areas
- Routes of travel
- Communication Lines
- Extent of vegetation cover
- Elevation and relief of the earth's surface
Care and Importance
Maps are printed on paper and require protection from water, mud and tearing. When
you mark on your map, use lighter lines, which are easily erased, without smearing. If
trimming the map, be careful not to cut any of the marginal information. Maps must be
protected because they can hold tactical information, such as:
- Friendly positions
- Friendly supply points
Map Illustrations
Symbols
- The mapmaker uses standard symbols
- They represent natural and manmade features
- Resemble as closely as possible, the actual features but as viewed from above
Map Colors - to ease the identification of features on the map, the topographic symbols
are usually printed in different colors, with each color identifying a class of features. The
colors vary with different types of maps, but on a standard, large scale, topographic map,
there are five basic colors.
Black - used to identify the majority of cultural or man-made features, such as
buildings, bridges, and roads not shown in red
Red - main roads built up areas, and special features such as dangerous or restricted
areas
Blue - is for water features: lakes, rivers, swamps, and streams
Green - identifies vegetation such as woods and orchards
Red Brown - all landforms such as contours, fills, and cuts
NOTE: Occasionally other colors may be used to show special information. These, as a rule,
will be indicated in the “margin of information”.
Marginal Information - instructions that are placed around the outer edges of the map are
known as margin of information. All maps are not the same, so every time a different map is
used, you must examine the margin of information carefully:
- Sheet Name - found in two places: The center of the upper margin and the lower right
margin
- Contour Interval - appears in the center lower margin and states the vertical distance
between adjacent contour lines on the map
- Grid Box - gives basic instruction on reading grids in determination
Declination Diagram - located in the lower margin and indicates the angular relationship of
true north, grid north and magnetic north (see figure 1):
Figure 1. Declination Diagram
- True North - a line from any position on the earth's surface connects at the North Pole.
Unlike grid lines, all lines of longitude are true north lines.
- Magnetic North - direction to the North Magnetic Pole, as indicated by the north-
seeking needle of a magnetic compass. The North Magnetic Pole is located in Canada
at Hudson Bay.
- Grid North - north that is established by the vertical grid lines on the map. The
variation between grid north and true north is due to the curvature of the earth.
Grid Magnetic (GM) Angle - the GM angle is an important factor in map reading. The GM
angle is used to convert magnetic azimuth to grid azimuth and vice versa:
- Grid azimuth - determined with a protractor and is measured from grid north.
- Magnetic azimuth - taken from a compass and measured from magnetic north.
Legend - located in the lower left margin. Illustrates and identifies some of the symbols on
the map. Every time a map is used, refer to the legend to prevent errors in symbol
identification (see figure 2). Other information found in the legend is the Sheet Name, Sheet
Number, Series Name, Edition Number, Index to Boundaries, Index Adjoining Sheets, and
Series Number.
Figure 2. Legend
Bar Scale - located at the center bottom of the margin, below the map face. Special "rulers,”
ground distance may be measured directly without having to convert the map scale ratio.
Normally, the scale for meters, yards, statute miles (land) and nautical miles (sea). Easy to
use, but notice that "zero" is not at the end of the scale (see figure 3).
2. MEASURING DISTANCE
Straight Line Distance - to measure line distance between two points:
- Lay a straight strip of paper on the map so the edge touches the center on both points.
- Make a tick mark on the edge of the paper at each point.
- Lay the paper strip along the scale that corresponds to the unit of measure you are
working with.
- Place the right tick mark of the paper strip on the largest full unit on the primary scale
(to the right of zero), allowing the remainder to fall on the extension of the scale (to the
left of zero).
Curved or Irregular Distance - to measure distance along a winding road, stream, or any other
curved line:
- Make a tick mark near one end of the irregular line to be measured.
- Align the paper strip along the center of the first straight portion of line.
- Make a tick mark at the other end of that portion on both the paper strip and the map.
- Keeping both tick marks together, pivot the strip at the second tick mark until another
straight portion of that line is aligned.
- Continue this process until the measurement is completed, then place the paper strip on
the appropriate bar scale, and determine the ground distance measured.
Figure 3. Bar Scale
3. PROTRACTOR (see figure 4)
There are several types of protractors. All of them divide the circle into units of angular
measure, and each has a scale around the outer edge and an index mark.
- The index mark is the center of the protractor circle from which all directions are
measured.
- The military protractor contains two scales; one in degrees (inner scale) and one in mils
(outer scale).
- This protractor represents the azimuth circle.
- The degree scale is graduated from 0
0
to 360
0
; each tick mark on the degree scale
represents one degree. A line from 0
0
to 180
0
is called the base line of the protractor.
Where the base line intersects the horizontal line, between 90
0
and 270
0
, is the index or
center of the protractor.
- When using the protractor, the base line is always oriented parallel to a north-south grid
line. The 0
0
or 360
0
mark is always toward the top or north on the map and the 90
0
mark is to the right.
4. THE GRID SYSTEM
System which tells the reader where specific locations or points are (see figure 5). A
network of lines, in the form of squares, placed on the face of the map. These squares are
somewhat like the blocks formed by the street system of a city. The "streets" in a grid all
have very simple names. The names are all numbers. Every tenth line is made heavier in
weight. This will help you find the line you are looking for. Each grid line on the map has
its own number. These numbers appear within the map on the line itself. Four digit numbers
Figure 4. Protractor
identify a 1000 square meter grid square. Six digits identify a 100-meter grid square. Eight
digits identify a 10-meter grid square. To locate a point by grid reference is a simple matter.
We follow a simple rule of map reading: READ RIGHT AND UP
5. COMPASS TERMS AND CONCEPTS
Azimuth - an angle measured in a clockwise direction from a north base line.
Grid Azimuth
- The heading due east is an azimuth of 90
degrees
- South - 180 degrees
- West - 270 degrees
- North - 360 or “0” degrees. When using an azimuth, the point from which the
azimuth originates is imagined to be the center of the azimuth circle.
Obtaining a Grid Azimuth
READ UP
507
4 Digit Step 2
8 Digit Step 4
Figure 5. Grid System
(a) On your map draw a line connecting two points
- Point A represents your present location
- Point B represents your destination
(b) Place the index of the protractor on point A.
(c) Ensure the 0 degree and the 180 degree
base line is parallel with the vertical grid
lines on your map.
(d) Read the azimuth from the degree (inside) scale; this is the grid azimuth from
point A to point B.
Back Azimuth
- Back azimuth is the reverse direction of a forward azimuth.
- It is comparable to doing an “about face”. To obtain a back azimuth from an
azimuth less than 180 degrees, add 180 degrees. If the azimuth is 180 degrees or
more, subtract 180.
6. LENSATIC COMPASS
The primary instrument used to determine and maintain direction during land navigation.
Parts of the Compass (see figure 6)
- Thumb loop - Graduated straight edge
- Short luminous line - Lens
- Luminous sighting dots - Fixed index line
- Luminous magnetic arrow, "Magnetic North" - Bezel ring
- Sighting slot - Cover
- Sighting wire - Rear sight
- Floating Dial – in both mils and degrees - Base
Compass Precautions
- Handle the compass with care. The dial is set with a delicate balance and shock could
damage it.
Figure 6. Lensatic Compass
- Reading should never be taken near visible masses of metal or electrical circuits.
- In cold weather, always carry the compass in its carrier outside your outer layer of
clothing. If it is carried inside of your clothing close to your body, it will fog when
exposed to the cold air.
Methods For Holding The Compass - the lensatic compass is used to determine or follow
magnetic azimuth both day and night. There are two recommended positions for holding the
compass when navigating:
Compass-to-Cheek Method - recommended when determining the azimuth to a distant
object.
- Raise the cover (with the sighting wire) straight up and raise the sight (lens) to an
angle about 45 degrees above the compass glass.
- Turn the thumb loop all the way down and put your thumb through it. Form a loose
fist under the compass to steady it with your other hand, and raise up to eye level.
- Look through the sighting slot, and align the compass by centering the sighting wire
in the sighting slot.
- Keeping the compass level and the sights aligned, rotate your entire body until the
sighting wire is aligned on a distant object.
- Now glance down through the lens and read the magnetic azimuth under the fixed
index line on the glass.
Center-Hold Position (see figure 7)
- Recommended holding position for a predetermined azimuth, both during the day
and night.
- Do not need to remove your helmet, weapon, grenades, or magazines as long as they
are not near the compass.
- Open the cover until it forms a straight edge.
- Pull the eyepiece to the rear most position.
- Next, place your thumb through the thumb loop.
- Form a steady base with your remaining fingers.
- Using your other hand, form a solid base for your compass.
- To measure an azimuth, simply turn your entire body toward the object. While
pointing the compass cover directly at the object, look down and read the azimuth
from beneath the black index line.
Figure 7. Center-Hold Position
Compass Use at Night
- All the luminous features on the compass will be used.
- The lensatic compass has two glass faces, one under the other. The top glass (bezel
ring) rotates; each click means it has turned three degrees.
- Turn the bezel 30 clicks to the left (counter clockwise); this is a total of 90 degrees.
- Using the center-hold method, rotate your body and compass until the magnetic
north seeking arrow is directly aligned under the short luminous line on the bezel
ring. Your compass is now set on magnetic azimuth of 90 degrees.
- Now all you have to do to march on this azimuth line at night is keep the magnetic
north seeking arrow and the short luminous line aligned and follow the direction of
the luminous dots on the cover of the compass.
7. ORIENTATION OF A MAP
A map is oriented when it is in position with north and south corresponding to north and
south on the ground.
Orienting a map with a compass
- With the map in a horizontal position, the compass straight edge is placed parallel to a
north-south grid with the cover of the compass pointing toward the top of the map.
- This will place the black line on the dial of the compass parallel to grid north.
- Since the needle on the compass points to magnetic north, we have a declination
diagram on the face of the compass formed by the index line and the compass needle.
- Rotate the map and compass until the direction on the declination diagram formed by
the black index line and the compass needle match the directions shown on the
declination diagram printed on the margin of the map. The map is then oriented.
- If the magnetic north arrow on the map is to the left of grid north, the compass reading
will equal the GM angle (given in the declination diagram).
- If the magnetic north is to the right of the grid north, the compass reading will equal
360 minus the GM angle.
Orienting Without A Compass: Terrain Association
- When a compass is not available, map orientation requires a careful examination of the
map and the ground to find linear features common to both, such as roads, railroads,
fence lines, power lines, etc.
- By aligning the feature on the map with the same feature on the ground, the map is
oriented.
- Orientation by this method must be checked to prevent the reversal of directions that
may occur if only one linear feature is used. Aligning two or more of these features
may prevent this reversal.
8. DETERMINING LOCATION BY MAP AND COMPASS
Basic method for determining locations on a map
Inspection and Estimation
- Usually the easiest and most simple
- Carefully survey road systems and topographical features in the immediate vicinity.
Orient the map to the ground
- Identify some prominent characteristic such as a road, junction, bridge, stream etc.,
which you can see on the ground and unmistakably identify on your map.
9. 90 DEGREE OFFSET METHOD
To bypass enemy positions or obstacles and stay oriented, detour around the obstacle by
moving at right angles for specified distances. Use this formula:
Right add 90 degrees; Left subtract 90 degrees (RALS) (see figure 8)
Figure 8. 90 Degree Offset Method
10. PACE COUNT
Used to keep a record of ground distance:
- Record your count in 100-meter increments
- Step off with your left foot and count every time it hits the deck
- Record your 100-meter increments by putting a knot in a rope or piece of string.
(Example: A student is walking an azimuth of 25 deg. That person must travel in this
direction for 500 meters. The students pace count is 65 paces for 100 meters. To figure
out how many paces the student must take – multiply your pace count by the distance.
DISTANCE divide by 100 x Pace Count (65).
11. ELEVATION AND RELIEF
Contour Lines - indicates elevation and relief on maps. A line representing an imaginary line
on the ground, along which all points are at the same elevation. Each contour line represents
an elevation above sea level and the amount of the contour interval is given in the marginal
information. On most maps, the contour lines are printed red-brown, starting at zero
elevation. Every fifth contour line is a heavier brown line. These heavy lines are known as
index contour lines. Also, the elevation will be given along this heavy brown line.
- The spacing of the lines indicates the nature of the slope. This has important military
significance.
- The closer the contour lines the steeper the terrain
Land Formations
Hill - a point or small area of high ground (see figure 9).
Figure 9
Valley - a stream course, which has at least, a limited extent of level ground bordered on
the sides by higher ground. Contours indicate a valley that is a “U" shaped, and the curve
of the contour crossing always points up (see figure 10).
Figure 10
Draw - a less developed stream in which there is essentially no level ground and
therefore, little or no maneuver room within its confines. The ground slopes upward on
each side and towards the head of the draw. Contour lines indicating a draw are 'V"
shaped, with the point of the "\/" toward the head of the draw (see figure 11).
Figure 11
Ridge - a line of high ground, normally with minor variations along its crest. The ridge is
not simply a line of hills but rather the ridge crest are higher than the ground on both
sides of the ridge (see figure 12).
Figure 12
Saddle - a dip or low point along the crest of a ridge. A saddle is not necessarily the
lower ground between two hilltops; it may simply be a dip or break along an otherwise
level ridge rest (see figure 13)
Figure 13
Depression - a low point or sinkhole surrounded on all sides by higher ground (see figure
14).
Figure 14
Cliff - a vertical, or near vertical, slope. When a slope is so steep that it cannot be shown
at the contour interval, it is shown by a ticked line carrying contours. The ticks always
point toward lower ground (see figure 15).
Figure 15
REFERENCES
Map Reading and Land Navigation, FM 3-25.26, Ch 2, 6, 9, 10, 11
ITS, (May 2001), Pgs 1-18-1 through 1-18-42