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67 Cards in this Set

  • Front
  • Back
True North
True North: Point on earth where lines of ___ converge
True North is __ used in order to find ___ when
doing basic land navigation
Direction definition:
position of one point in relation to another
Direction required elements 2:
• An understood base line
• An angle measured from that base line
Magnetic North
Lensatic compass always points to __ __
Magnetic North
Magnetic North:
Lines __ __ on map.
Used to navigate in the __.
not shown-field
Grid North
Grid North:
• ___ lines on the map
• Do not converge at __ __
• Based on Military Grid Reference System (MGRS)
Parallel-North Pole
Declination definition:
The angular difference between true north and grid north or magnetic north. Declination is ALWAYS measured from True North.
Magnetic Declination: Measures from __ north to __ north
• true - magnetic
• Can be east or west
• Usually measured in degrees
e.g. 5°W
Grid Declination:
Measures from __ north to __ north
• true - grid
• Can be east or west
• Usually measured in degrees
e.g. 6°E
Azimuth: A horizontal angle measured __ from a __ line. An azimuth can be from any of the three base lines (__)described above.
clockwise-base-True North, Magnetic North, or Grid North
A back azimuth is the reverse (plus or minus 180°) of
an azimuth, either __ or __.
Back Azimuth: Less than 180°
add 180°
Back Azimuth: More than 180°
subtract 180°
The magnetic declination (the relationship between __ north and __ north and, by association, __ north) changes daily in small and largely unpredictable
Three Methods To Update The GM
Angle 3:
To Update
The GM
1. The method of choice is to call Defense Mapping Agency (DMA) or United States Geological Survey (USGS) and request changes (go through unit intelligence officer, the S-2).
2. Some older maps may have a “projected annual magnetic change” statement at the bottom of the declination diagram. If DMA or USGS cannot be contacted, use this “projected” data.
3. Use a formula
Formula to update The GM Angle:
1. Determine the number of __.

2 Multiply the number of
years by the __ __.
3 Determine the number of __ of change (if any).
4 Apply change to update GM angle.
years-annual change-degrees
Sighting Wire: For sighting in on objects for which an exact azimuth is needed
• For compass calibration
• Is comparable to the front sight post of the service rifle
Graduated Straightedge
Luminous Sighting Dots
Bezel Ring: • Holds the upper glass crystal in place
• Helps preset a direction for night compass navigation
• Contains 120 clicks when rotated fully; each click equals 3°
Floating Dial
Fixed Black Index Line:• Stationary line used as a reference line for determining direction
• When the compass is held properly, the azimuth found directly under the black index line identifies the direction that the compass is pointing
Luminous Magnetic Arrow
Short Luminous Line
Sighting Slot
Thumb loop: Serves as a retaining device to secure the compass in the closed position
Compass dial: • Can be locked in place by closing the __
• Is delicately balanced and free floating when in use
• Contains two complete circular scales, one in __ and __
eyepiece-Degrees (red scale)-Mils (black scale)
Open your compass to see that the:
− Cover glass is not broken, clouded, or cracked
− Compass dial does not stick
Inspect the front cover to see if the cover sighting wire is __
missing or bent. If it is, use the center of the opening for sighting purposes, not the wire.
Inspect the eyepiece to be sure: (4)
− It is placed flat against the cover glass
− The index line on the cover glass bisects the sight slot
− With the compass closed, the sighting wire also bisects the sight slot
− The eyepiece is not bent. Gently bend the eyepiece back into proper alignment, if necessary.
Do not place the compass under a __ __ prior to use; you may damage your compass.
light source
The following parts should appear luminous: (4)
- The two dots situated at opposite ends of the sighting wire on the front cover
- The luminous line on the crystal
- The luminous line on the north-seeking arrow
- The luminous dots under the letters "E" and "W" on the face of the compass
Maintenance procedures:
• Rinse in __ __, especially after exposure to salt water.
• Brush off dirt and grime.
• Ensure the "__" on the bezel ring are free of dirt.
• Check movement of the __ __ to ensure it is free moving.
fresh water-ridges-rear sight
It is highly recommended that you __ __ walk through the woods, looking for your objective, with the compass constantly in your hand.
Safe Distances in Meters-High tension power lines
Safe Distances in Meters-Field gun, truck or tank
Safe Distances in Meters-Telegraph/telephone wires or barbed wire
Safe Distances in Meters-Machine gun
Safe Distances in Meters-Service Rifle
Kevlar helmets have __ effect.
Compass calibration Step 1: Note the calibration point azimuth: the known __ __ from the calibration point to a __ point.
magnetic azimuth-designated
Compass calibration Step 2:
Shoot an azimuth from the calibration point to the designated point using the __ technique. Check for effects on your compass from your eyeglasses, watches, rings, etc. If you wear these items in the field, be sure to wear them when calibrating your compass.
Compass calibration Step 3:
Compare azimuths
Comparing azimuths when calibrating: Greater than the calibration point azimuth, then you must __ the difference between the two azimuths (the calibration point value) to your __ magnetic azimuth. Conversely, you must also subtract this value when converting from an actual compass (magnetic) azimuth to a grid azimuth.
Comparing azimuths when calibrating: Less than the calibration point azimuth, then you must __ the difference between the two azimuths (the calibration point value) from your computed magnetic azimuth. Conversely, you must add this value when converting from an actual compass (magnetic) azimuth to a grid azimuth.
Center Hold Technique
Pull your __ along your sides. The compass should
be at __ level.
The advantages of the center-hold technique are: (3)
Fast and easy
• Under any visibility conditions
• Without taking off helmet or removing rifle from sling arms
compass-to-cheek technique: __ at the dial to read the azimuth. Ensure the compass dial is __.
The advantages of the compass-to-cheek technique are:
− Is more accurate than the center-hold technique
− Is ideal when:
Employing intersection and resection techniques
A more accurate azimuth is required.
Factors Affecting Pace: 7
1. Slope
2. Winds
3. Surface
4. Elements
5. Clothing and equipment
6. Stamina
7. Limited visibility/night
Attack point- an __ recognizable feature positively identified on the map and on the ground, preferably __ meters or less from your objective.
Collecting features - features that you plan to __ __ __ to your objective and serve as __.
cross en route-checkpoints
Limiting/catching feature - a predetermined feature, preferably linear (such as a stream, finger, or road), __ __ __.
beyond your objective
The three basic techniques used for land navigation are
dead reckoning, terrain association, and a combination of dead reckoning
and terrain association.
Dead Reckoning: 5
1. Locate starting point on map
2. Determine the grid azimuth between the two points and convert it to a magnetic azimuth
3. Determine distance and convert pace count
4. Set magnetic azimuth
5. Pick an object in the distance along your azimuth.
Factors that may cause you to drift from your intended azimuth are: 4
1 Physical attributes
2 Unbalanced load
3 Elements
4 Movement around obstacles
Terrain Association
The process of using terrain features to guide the navigator to the objective with little or no reliance on the compass.
A combination of dead reckoning and terrain association
is the
best method for beginner and intermediate level navigators.
Combining dead reckoning and terrain association can be used under almost any conditions of terrain and weather.
Orientation via Inspection.
orient the
map by aligning recognizable terrain features on the map with the corresponding features on the ground.
Orientation to Grid and Magnetic North: 5
1. Open the compass so the cover is flat.
2. Align the compass on a N/S grid line (use the straight edge, ensuring the cover points north).
3. Before you orient your map, ensure that you figure in the compass error.
4. Leaving the compass in place, rotate the map until the compass face looks exactly like the declination diagram.
5. Once the map is oriented, leave the map in place and rotate the compass until the straight edge is on a line between your start point and the objective. Now, simply read the azimuth under the black index line. This is the magnetic azimuth--no further conversion need be made.
Intentional Offset is a process of intentionally offsetting your magnetic azimuth between:
1° and 4° to take advantage of a linear terrain feature.
90° Offset Rule used when
you are not able to cross a sizable obstacle.