Monday, August 07, 2006

Terrain Association

Mostly Cajun says, in comments:
I used to pride myself in army land-nav, when I could locate myself within a hundred meters on a paper map by looking at landmarks. The GPS makes that obsolete for the most part.
Me too.

I know the Cajun used to be a tanker. When we were younger soldiers, either at Disney Barracks, on in the 4th Brigade, they taught us land nav. They'd take you out in the woods and instruct you on a map and compass, then turn you loose in the woods to maneuver through a predetermined map course. When it came time to use those skills in a tank, you quickly learned that the compass was worthless. It is a magnetic device and a tanker, by definition is surrounded by 53 tons of steel. Even at night, when you'd laager the tanks for chow and fuel, the leadership might walk out a hundred meters or so and look at a map while sitting under a tree. With five tanks arrayed in a semicircle, there is a half million pounds of ferrous metal. That much steel will skew the compass reading. For tankers, compasses are worthless.

What we learned to do was read a map on the move, by associating known points on the ground. A stream crossing, a road intersection, a particular mountaintop. With those things in mind it is easy to associate your location with a spot on the map. It didn't have to be precise, because we were tankers, By God, and if we were within a hundred meters of a spot, we owned it. Let the infantry worry about 8 digit grid coordinates, we were Armor, and compasses were for people with three mile per hour minds.

During my last tour before retirement, I was assigned to a NG Armor batallion (1/156, LANG). We assigned assembly points to the companies and while visiting a company I noticed that the commander had changed the location of his assembly point by about 1500 meters. A commander has perogatives that he should discuss with his higher commander, and it wasn't any of my business, so I made a mark on my map and said nothing. Later I heard a radio message from our evaluators to our commander. The colonel said that I should answer the message, so I picked up the mike and gave the evaluator a coodinate to our location. When I dropped the mike, the Commander told me that I was screwed up, that I had given the wrong coordinate.

I replied, "No, sir. We are at that grid. The company commander changed his assembly area."

The boss swiveled on the young captain. "Is that so?"

"Yessir. The major gave the correct coordinates."

At that point, I had not picked up a compass in the field for ... oh... eighteen years. Terrain association had served me well and continues to serve me well. I can read a map with the best of them.

Having said all that, this little GPS is a darlin. I can see that it will become real useful.

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