TAR 713 Land Navigation Techniques Flashcards
Dead Reckoning
The process of following an established azimuth for a specified distance
Dead Reckoning Steps
- Locate the starting point of each leg
- Use resection, intersection, and attack points
- On your map, determine azimuth from starting point to finish point, then convert the grid azimuth to a magnetic azimuth
- Determine the horizontal distance to that point on your map and convert it to a pace count
Resection
The method of locating one’s position on a map by determining the grid azimuth to at least two well defined locations that can be pinpointed
Resection: Map and Compass Steps
- Orient the map using the compass
- Identify two or three known distance locations on the ground and Mark them on the map
- Measure the magnetic azimuths
- Convert to grid azimuths
- Use a protractor to draw back azimuth lines
The intersection is your location
Magnetic Azimuth
The arc between the point on the horizon and the direction of magnetic north
Grid Azimuth
The angle between grid north and a line drawn on a map
True North
North according to earth’s axis, not magnetic north
GM Angle
The angular distance between grid north and magnetic north
- Expressed to nearest 1/2 degree
Declination
The difference between the three types of north
Magnetic North
North as determined by earth’s magnetic field
Grid North
North as determined on a flat map
- Parallel lines that do not converge
Convert Grid to Magnetic
- Add if westerly
- Subtract if easterly
- LARS (Left Add, Right Subtract)
Convert Magnetic to Grid
- Subtract if westerly
- Add if easterly
- RALS (Right Add Left Subtract)
LARS
Left Add, Right Subtract
Attack Point
An easily identifiable and recognizable feature on the map and on the ground
- Preferably 300m or less from your objective
Steering Mark
A well defined object on the ground in the direction of travel toward which the navigator must steer
Deliberate Offset
A process of intentionally offsetting to a particular direction when your objective is located on a linear feature
- One degree offset equals 17m for every 1,000m traveled
Number of MILS in Compass
6,400
RALS
Move right add, move left subtract
RALS Rule
- Used to bypass obstacles or enemy positions by detouring around them and still staying oriented to them by moving at right angles for specified distances
- At night, hold compass and turn until center of the E or W is under the luminous light
Collecting Features
- Features you plan to cross at any particular leg of a course
- Checkpoints to your objective
- Ideally 3+ per leg
- Check azimuths as you cross
Limiting/Stopping Feature
- A feature, preferably linear, beyond the objective
- Indicates you’ve traveled too far
Drift
The tendency to veer from the planned path
Factors that Affect Drift
- Terrain
- Obstacles
- Error in holding compass
- Compass error
Terrain Association
The process of using terrain features to guide the navigator to the objective
Terrain Association Steps
- Locate your starting point and finish point
- Identify all terrain features between the two points
- Move to finish point by reading the ground along the direction of movement
Keys to Terrain Association
- Use contour lines
- Match terrain to map by examination
- Compare the vegetation on map
- Adjust for terrain masking by vegetation
- Use hydrography
- Use man made features
Combo Land Nav Steps
- Determine start point and objective
- ID a prominent terrain feature <300m from objective as attack point
- Determine magnetic azimuth and pace count to objective
- Determine route to attack point
- ID collecting features and collect as you move
- ID limiting feature
- Move to objective using steering marks
- Continually check azimuth and pace count
Field Expedient Methods
- Shadow Tip Method
- North Star
- Southern Cross
Shadow Tip Method
- Used when compass not available
- Place stick vertically in level ground with a distinct shadow.
- Mark shadow tip with a stone
- First mark is always the west direction - Wait 10-15 minutes for shadow to move
- Mark the new shadow tip position - Draw a straight line through the two marks made on the shadow tips
- This is the east-west line - Stand with the first mark to your left and the second to your right
- First mark is east, second is west
North Star
- Polaris
- Five finger widths up from the two end stars in Big Dipper (Ursa Major) bowl
- Also the end of the tail of Little Dipper (Ursa Minor)
Southern Cross
- Only visible in the Southern Hemisphere
- Four finger widths from bottom star marks due south
- Shown on Australian flag and Raider emblem
Searching Techniques
- Circle Search
- Box Search
- No more than 25 meters
Intersection
Shooting an azimuth at one point from two known locations, then determining location by their intersection on the map
Back Azimuth
- Plus (<180) or minus (>180) 180 degrees, 3200 mils from original azimuth
- Can help determine how far off course you are
Using a Back Azimuth
- When you lose sight of the objective, but not the known starting point
- Backsight to starting point, then calculate back azimuth to current position
- The difference between original azimuth and back azimuth is how off course you are
