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Offline Flyin6

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Pioneering Skills: Land Navigation
« on: August 09, 2019, 09:45:22 AM »
This will be part of a series of mini classes to better prepare one for hiking or other activities in wilderness  or more rural areas. This mini class will deal with Land Navigation using the HHM (Hand held map), Mark-1 eyeballs, ;-) and a good lensatic compass like those issued to our warriors in the military.

Terrain association is THE key element to getting oneself oriented aside from electronic aids. But once you get oriented, you need to stay that way. I used to teach that portion of our green platoon for new hopefuls entering the regiment. Map prep and map study is very important

Some tips: first use the right scale map

The 1:50,000 topo with the mgrs system is the standard, followed by the 1:24,000 being very useful, especially with slower or no speeds. Of course with the higher speeds of flying low level, we used the 1:250,000 scale JOG (Joint Operation Graphic) map, but that has no application to this discussion

Study the legend. You can learn alot and the map will really start to "Talk" to you. You'll find out that that little circle with a dot at the center is the symbol for a tower! What we would do is to prep our maps by taking a highlighter and actually drawing a small tower (Like an inverted "V") over the location. Then every time you get to a cleared area or high ground find the towers then compare the terrain with what you are sitting on.

Learn to do "resection" (Goggle that) from two known points with a good compass. The intersection of those two lines is your location.

Do not plan to move large distances in forested terrain. 5-6 kilometers is a good night's walk, like all night long.

Fold your map and maybe even cut it into panels so that it can be flipped through like a book. If you do that give each row a similar marking in the same corner so when you flip a page, you won't be one map sheet off. For surface navigation, this may not be necessary unless you are going to be operating over a larger area for quite some time.

Take note of the magnetic declination as it can be great in some areas of the world. Then note the date of the map and the annual rate of change. Do the math and come up with the actual variance than plot a angle showing the variance and put it in a corner somewhere. You may be surprised to find out your 270 degrees is actually 258 degrees. It can get that big, and the world wide annual rate of change is really picking up. Most old maps, circa 1970's will be up to 20 degrees off!

Take the map and study it in the bathroom with the lights off and the window shades pulled. Note that the detail is far less. You may want to highlight or trace other every indes grid line, like every 5th one to give you an idea of slope and help in low light situations.

Bobby can teach this better than I, but you need to learn your pace count.

Mark out 100 meters. Not 100 yards, but 100 meters. Mark it out on level ground hard surface like a road. Now walk it both directions  twice. Take the pace count from each trip, add together and divide by 4. This is your level ground pace count,
Ok we have a theoretical 78 steps on average to go one hundred meters for our imaginary navigator. Now set the course up on a grassy and clumpy field and walk it again, 4 times, both directions. Do the math. You notice it took a couple more steps? Your average increased to 80-81?? OK, whatever it is, it "IS."

Next set up another course on a slope. Do it in several spots. Walk it upslope and record that number, then down slope and record that number of steps in another column. Do it on a shallow and on a steeper slope. Do a lot of walking. Do the math again and record your results

Notice that the number of steps increases again. Down hill could take more steps than going uphill? Surprised?

Record this data.

Now make up a couple lengths of 550 cord and tie a knot on either end. Then tie ten knots tightly with another piece of 550 cord onto the length. Create it so that with some resistance, you can pull the knot from one end to the other.

You can do this with only one if you want or create several. I use one for flat and level, one for upslope and one for downslope.

Since the number of steps required to go 100 meters varies slightly you can be very accurate by using the several length method.

So as you start off from a known point and move out, say, toward that distant peak or tower, which we know is due west, we start to count steps. Every time you hit your pace count number for the given terrain, pull one knot to the bottom. After going for awhile, look and notice that you have, lets say, five knots pulled down. That means you have traveled 500 meters, or 1/2 kilometer, equal to one half the distance of one grid square. Look due west from where you started, in this example at the point that is 500 meters west and that is your location.

One thing I would do is also carry a length of white chord. I would mark a black dot at every kilometer and a red dot in between the black dots for my 1/2 click distances. Simply lay the string on the map along your path and you can plot your location. I use a string because you almost never travel in a straight line, and a string can be laid down in any shape needed.

Again, let me say I am no expert on surface navigation, but I have done it some. I am an expert on low level aerial navigation, so for whatever of that translates, I'd be happy to help. Your standard issue Infantryman will easily make the fool of any pilot in the back country!
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Offline cj7ox

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Re: Pioneering Skills: Land Navigation
« Reply #1 on: August 10, 2019, 06:16:33 AM »
Methods to find a location, or your location, on a map:

Intersection
This is a method for finding out a location on a map from two known locations. Typically, in the ground pounding military, we will ideally have two observers at two distinct and separate locations. They both see an object from their location, but do not know the exact coordinates of that object on the map. Here are the steps they take to determine the location:

1. Each observer will use their compass to "shoot an azimuth" (identify the bearing in degrees to the object using the compass) to the object. They capture the azimuth/bearing, and calculate to obtain a "grid azimuth" from the "magnetic azimuth", using the formula under the declination diagram on the map.

2. Each observer shares the information with each other.

3. From your location on the map, draw a line along the azimuth/bearing.

4. From the other location, draw a line along the azimuth/bearing they provided.

5. Where the two lines intersect is the location of the object you have sighted.

Resection
Resection is much like intersection, but you are trying to locate your position on the map. Here are the steps for performing resection:

1. Identify two terrain features that you can identify visually, and on your map. These should be objects that have longevity, like a water tower, railroad bridge, or natural terrain features like a lone hilltop.

2. Shoot an azimuth to each of these terrain features.

3. Convert the azimuths from magnetic to grid, following the formula below the declination diagram.

4. Calculate a back azimuth for each, by subtracting or adding 180* (if the azimuth if more than 180*, subtract; less than 180*, add)

5. Draw a line on your map from each terrain feature, following the back azimuths. Where they intersect is your location.

Modified Resection
Modified resection is half the work of resection, but requires you to be located on a "linear terrain feature". For instance, you are standing on the bank of a river that is depicted on your map, but want to know your exact location. Other examples of a linear terrain feature are roads, rail lines, power lines, etc. Remember to check the dates on your map when using roads or power lines. These are features which tend to change fairly frequently. Rivers and rail lines tend to be much more permanent. The steps for resection are as follows:

1. Using the map, identify the linear terrain feature you are on.

2. Identify a terrain feature visually and on the map.

3. Shoot an azimuth to the terrain feature.

4. Convert to a grid azimuth using the formula from the declination diagram.

5. Convert to a back azimuth by adding/subtracting 180*.

6. Draw the back azimuth on the map from the terrain feature you identified.

7. Where that line crosses the linear terrain feature you are on is your location on the map.
~Sean M. Davis

“The citizens of a free state ought to consist of those only who bear arms.” ~Aristotle

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