Direction - Azimuths
An azimuth is defined as a horizontal angle measured clockwise from a north base line. This north base line could be true north, magnetic north, or grid north. The azimuth is the most common military method to express direction. When using an azimuth, the point from which the azimuth originates is the center of an imaginary circle. This circle is divided into 360° or 6400 mils (see Appendix G).
a. Back Azimuth. A back azimuth is the opposite direction of an azimuth. It is comparable to doing an "about face." To obtain a back azimuth from an azimuth add 180° if the azimuth is 180° or less; or subtract 180° if the azimuth is 180° or more. The back azimuth of 180° may be stated as 0° or 360°. For mils, if the azimuth is less than 3200 mils, add 3200 mils; if the azimuth is more than 3200 mils, subtract 3200 mils.
b. Magnetic Azimuth. The magnetic azimuth is determined by using magnetic instruments, such as lensatic and M2 compasses. Refer to Chapter 9, paragraph 4, for details.
c. FieldExpedient Methods. Several fieldexpedient methods to determine direction are discussed in Chapter 9, paragraph 5.