This circle is divided into 360 degrees or 6400 mils ( Appendix G).Ī. When using an azimuth, the point from which the azimuth originates is the center of an imaginary circle ( Figure 6-2). The azimuth is the most common military method to express direction. This north base line could be true north, magnetic north, or grid north. AZIMUTHSĪn azimuth is defined as a horizontal angle measured clockwise from a north base line. Grid north may be symbolized by the letters GN or the letter “y” ( Figure 6-1). The north that is established by using the vertical grid lines on the map. Magnetic readings are obtained with magnetic instruments, such as lensatic and M2 compasses.Ĭ. The magnetic north is usually symbolized by a line ending with half of an arrowhead ( Figure 6-1). The direction to the north magnetic pole, as indicated by the north-seeking needle of a magnetic instrument. True north is usually represented by a star ( Figure 6-1). All lines of longitude are true north lines. A line from any point on the earth’s surface to the north pole. The most commonly used are magnetic and grid.Ī. There are three base lines- true north, magnetic north, and grid north. To express direction as a unit of angular measure, there must be a starting point or zero measure and a point of reference These two points designate the base or reference line. In order to measure something, there must always be a starting point or zero measurement. The grad is divided into 100 centesimal minutes (centigrads) and the minute into 100 centesimal seconds (milligrads). There are 400 grads in a circle (a 90-degree right angle equals 100 grads). The grad is a metric unit of measure found on some foreign maps. To convert degrees to mils, multiply degrees by 17.78.Ĭ. A circle equals 6400 mils divided by 360 degrees, or 17.78 mils per degree. A relationship can be established between degrees and mils. The mil expresses the size of an angle formed when a circle is divided into 6,400 angles, with the vertex of the angles at the center of the circle. Another unit of measure, the mil (abbreviated ), is used mainly in artillery, tank, and mortar gunnery. The most common unit of measure is the degree (°) with its subdivisions of minutes (‘) and seconds (“).ī. Directions are expressed as units of angular measure.Ī. Military personnel need a way of expressing direction that is accurate, is adaptable to any part of the world, and has a common unit of measure. It also includes some advanced aspects of map reading, such as intersection, resection, modified resection, and polar plots. It explains the use of some field-expedient methods to find directions, the declination diagram, and the conversion of azimuths from grid to magnetic and vice versa. It explains in detail how to determine the grid and the magnetic azimuths with the use of the protractor and the compass. It can be expressed as right, left, straight ahead, and so forth but then the question arises, “To the right of what?” This chapter defines the word azimuth and the three different norths. Direction plays an important role in a soldier’s everyday life. Always keep your land navigation skills fresh by practicing with a map, compass and military protractor.Being in the right place at the prescribed time is necessary to successfully accomplish military missions. Moisture is a common malfunction of the GPS.ĭon’t let yourself be caught relying solely on electronics or batteries that can fail you. It can be jammed and detected when near or behind enemy lines. GPS readings are distorted during thunderstorms, electronic interferences and when bombing support is very close on enemy positions. The GPS will not penetrate sandstorms, rainstorms, snowstorms, smoke, structures, forest canopies, and thick cloud cover. Protractors without the conversion formula will provide a reading that is off the exact grid coordinate position. The RM Military Square Protractor is the only protractor with a printed formula and a diagram to align map grid north to match the compass magnetic north. The only known BACK-UP of the GPS when it malfunctions is your ability to use a military protractor and sighting compass. Description Military Square Protractor #21
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