Convert grid azimuths to back azimuths

Convert grid azimuths to back azimuths

This Web course consists of four lessons and four student activities Lesson 1 - Determine magnetic azimuths using a lensatic compass. Lesson 2 - Convert magnetic azimuths to grid azimuths. Lesson 3 - Convert grid azimuths to back azimuths. Lesson 4 - Plot back azimuths and determine location on a topographical map.

You have done the first two of the four steps in locating yourself on a topographical map. You have located two distant known points. You have converted their magnetic direction to a grid (or map) direction. You know the direction to them but not to your location. To determine your location you must compute the back direction. The back azimuth is determined by adding or subtracting 180 degrees to the grid azimuth. This lesson will assist you in learning how to convert the grid azimuth to a back azimuth. In the fourth (last lesson) you will be able to plot the two back azimuths and determine your location. First you learn to convert grid azimuths to back azimuths. To determine back azimuths that are less than 180 degrees add 180 degrees. To determine back azimuths that are more than 180 degrees subtract 180 degrees. Examples: Grid azimuth = 107 degrees (add 180) 107 + 180 = 287 degrees Grid azimuth = 243 degrees (subtract 180) 243 - 180 = 063 degrees