Determining the Mounting Azimuth (MAZ)
To determine the mounting azimuth (MAZ), round off the direction of fire (DOF) to the nearest 50 mils.
If the direction is Then round to Example
0-24 00 DOF 3220 = MAZ 3200 25-49 50 DOF 1625 = MAZ 1650 51-74 50 DOF 1854 = MAZ 1850 75-99 100 DOF 2185 = MAZ 2200 Superimposing the Referred Deflection
To superimpose the referred deflection, you would first index the mounting azimuth on the plotting board; then you would write the referred deflection on the azimuth disk underneath the mounting azimuth. The referred deflection can be any 100-mil deflection from 0 to 6300. The referred deflection
normally used is 2800 to the front or 0700 to the rear. Using the left add right subtract (LARS) rule, the disk will normally be numbered 400 mils to the left and 400 mils to the right of the referred deflection, which is usually enough to cover the area of operations. However, if needed, the deflection scale can be superimposed all the way around the azimuth disk.
The illustration below shows a superimposition of referred deflection under the mounting azimuth.
Determining
Firing Data After you have plotted the first round on the DOF at the determined range and superimposed the deflection scale, rotate the azimuth disk until the first round
is over the vertical centerline. Then you will determine the deflection and the range.
MCI Course 0331K 2-26 Study Unit 2, Lesson 2
Observed Firing Chart Pivot Point Method,
ContinuedDetermining
Deflection To determine the deflection to fire the first round, you will use the deflection scale and the left portion of the vernier scale. The table and illustration below
explains the process for getting the data.
Step Action 1 The first two digits are read from the deflection scale. Since
deflections increase to the left, the first number to the right of the index mark is read.
2 The third digit is read from the 10-mil graduations between
deflection scale numbers by counting the 10-mil graduations on the azimuth disk, to the index mark.
3 The fourth digit is read at the vernier scale for deflections; use the left half of the vernier scale. Count the 1-mil graduations starting at the 0 index mark to the left until one of the 1-mil graduations on the vernier scale and one of the 10-mil graduations on the azimuth disk line up.
Observed Firing Chart Pivot Point Method,
ContinuedDetermining
Range To determine the range, you will rotate the plot over the vertical centerline and read the range to the nearest 25 meters. Then you enter the firing table
and determine the charge as described in the table below.
Step Action 1 Open the tabular fire table (TFT) to part one and turn back one
page to the charge vs. range chart. This chart may be used to determine the lowest charge to engage the target. Always use the lowest charge.
2 Use the chart by reading the range bar at the bottom of the chart and reading up until the charge is bisected.
3 Turn to the proper charge in table D, locate the range to the target and read right to obtain the elevation setting to engage the target.
MCI Course 0331K 2-28 Study Unit 2, Lesson 2
Observed Firing Chart Pivot Point Method,
ContinuedCharge Versus
Range The illustration below depicts a charge versus range chart.
Table D The illustration below depicts an example of table D for M879 ammunition.
Observed Firing Chart Pivot Point Method,
ContinuedPlotting the Observer’s Corrections
To plot the observer’s corrections, you will first index the observer’s direction to the target. (The OT direction is given in the call for fire or with the first correction.) Going from the first plot, apply the observer’s corrections.
Example As an example, we will assume that the OT direction is 3050, and the
observer sends “Right, 50; drop, 200.” Given this information, you will follow the steps in the table below.
Step Action 1 Index the OT direction on the rotating disk.
2 Apply the correction from the first shot. You will go one square to the right, and go four squares down on your plotting board.
3 In this square make a small plot, circle it, and label it “No. 2.” 4 Rotate the disk until the No. 2 plot is over the vertical centerline
to determine firing data. 5 Read the deflection and range.
6 Using the firing table, determine the charge and elevation to fire the round, and compute the subsequent data.
7 Once end of mission (EOM) has been given, update the plotting board by erasing all plots except the final plot.
8 Encircle that plot with a hollow cross and number it with the target number.
Engagement of
Targets To process other missions, you will need to perform the following actions for each method listed in the table below.
Method Action
Grid Go back to map, plot the target location, and determine the range and direction.
Shift Index the forward observers (FO) direction to the target and apply the correction from the known point, which must be plotted on the plotting board.
Polar Index direction and distance from the FO’s position to the target. If the FO’s position is not known, you must first do a resection.
MCI Course 0331K 2-30 Study Unit 2, Lesson 2
Observed Firing Chart Pivot Point Method,
ContinuedResection To find the FO’s position through a resection, you will follow the steps in the
table below.
Step Action 1 Obtain two OT directions from previously fired missions.
2 Index the direction from the first mission and draw a line straight down on the board from the known point.
3 Repeat procedure in step 2 for the second direction. Note: The intersection of these lines is the FO’s location.