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UTM Coordinates Introduction

posted Mar 3, 2015, 1:51 PM by Richard Qualls
UTM – Universal Transverse Mercator – is a metric based coordinate system to determine where in the world something is located. While Latitude and Longitude divide the world into degrees, minutes, seconds; UTM divides the world into meters and kilometers. The system was developed by the U.S. Army Corp of Engineers in the 1940s and has been adopted by most militaries around the world.

UTM divides the world into 60 vertical zones of 6 degrees for each zone. UTM then divides the world into 20 horizontal zones of 8 degrees each. The horizontal zones do not include the Polar Regions.  Vertical zones are numbered and horizontal zones are assigned letters (Note: A, B, I, O, Y, and Z are not used). Vertical zones are numbered starting at the International Dateline (180 degrees) and work eastward. Horizontal zones start at 80 degrees south and work their way northward. Virginia Beach is located in Zone 18S.

UTM charts are divided into 1,000 meter squares. Coordinates are read in an easterly fashion – reading left to right and then read northerly – bottom to top. The saying is “Read right up!” in other words, we find the easting and then northing; reading how far east are we and then how for north are we. 

The star on the above chart was our mission base location for our squadron SAREX. To find the coordinates you must first read from the left to the right to get our Easting position – 0407450. You then read from the bottom to the top to get our Northing position – 4086080. These coordinates will get you with a 10 meter square position. Over all the coordinates would be 18S 0407450 4086080. This is the grid, the easting, and the northing. Unlike Latitude and Longitude, with UTM there is only one place on earth with these coordinates. 

UTM charts are divided into 1,000 meter squares. The large numbers represent these squares such as the 07 and the 86. To further subdivide into 100 meters, and 10 meters you can use the scales on the chart or a small plastic square with additional graduations which fits over the grids. 

Most aircraft still use Latitude and Longitude. Since each UTM grid covers 6 degrees of longitude and 8 degrees of latitude aircraft will quickly fly off the UTM grid. Keeping track of which grid they are in creates a navigational hardship. For ground personal UTM is a great system as we can easily locate our position down to a 10 meter square.  Providing these coordinates to mission base allows everyone to quickly know exactly where you are located.