Results for map reading

Map Reading and Land Navigation

TC 3-25.26 is the Army's map reading and land navigation manual: grids, marginal information, terrain features, azimuths, and navigation techniques. Dated November 2013, it is still the active reference used on land navigation courses and at boards. Note the designator -- it is a TC, not an FM or ATP.

What are the three norths shown on a military map?

True north, magnetic north, and grid north. They appear together in the declination diagram in the map margin. True north is shown by a star, grid north by the letters GN, and magnetic north by a half arrow.

What do the standard colors on a military map represent?

Black shows man-made features. Blue shows water. Green shows vegetation. Brown shows relief features such as contour lines. Red classifies main roads and built-up areas. Red-brown replaces both red and brown on maps printed for red-light reading.

What is the rule for reading a grid coordinate?

Read right and up. Read the easting first, left to right along the bottom, then the northing, bottom to top. The digits are always split evenly between the two.

How do you determine a back azimuth?

If the azimuth is less than 180 degrees, add 180 degrees. If it is 180 degrees or more, subtract 180 degrees. In mils, add or subtract 3,200.

How precisely does a four-, six-, eight-, and ten-digit grid coordinate locate a point?

Four digits locate a point to within 1,000 meters, six digits to within 100 meters, eight digits to within 10 meters, and ten digits to within 1 meter.

What are the five major terrain features?

Hill, ridge, valley, saddle, and depression.

What are the three minor terrain features and the two supplementary terrain features?

The three minor terrain features are draw, spur, and cliff. The two supplementary terrain features are cut and fill, both of which are man-made.

What are the three parts of a complete military grid reference system coordinate?

The grid zone designation, the 100,000-meter square identifier, and the numerical grid coordinate read to the required precision.

What are the three types of contour lines?

Index contours, which are heavier and carry the elevation number; intermediate contours, the lighter lines between index contours that are not numbered; and supplementary contours, dashed lines that show detail at half the contour interval.

What is a pace count and how do you establish one?

A pace count is the number of paces you take to cover a known distance, and it is how you keep track of distance while navigating dismounted. Establish it by walking a measured 100-meter course several times, counting one pace each time the same foot strikes the ground, then averaging the counts. Re-check it for hills, heavy brush, sand, snow, darkness, and a heavy load, because all of them change it.

What is the difference between a draw and a spur?

A draw is a less developed stream course where the ground slopes upward on three sides and downward in one direction; water drains through it. A spur is a short, sloping line of higher ground extending out from the side of a ridge; water drains away from it on both sides. On a map the contour lines of a draw point toward high ground and those of a spur point away from it.

What is the difference between intersection and resection?

Intersection locates an unknown point on the ground by sighting on it from two or more known positions. Resection locates your own unknown position by sighting on two or more known, plotted points. Modified resection fixes your position when you are already on a linear feature such as a road or a stream.

What is the G-M angle?

The grid-magnetic angle: the angular difference between grid north and magnetic north for that map sheet. It is shown in the declination diagram along with the conversion instructions used to change a magnetic azimuth to a grid azimuth or the reverse. Always use the conversion notes printed on the sheet you are working from.