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ELEMENTS OF FIRST TRANSMISSION

  1. CALL FOR FIRE. The call for fire is a concise message prepared and sent to the Fire Direction Center (FDC) by you, the observer. It contains all of the information that the FDC needs to compute firing data and to decide the best method of attack. You must send the call for fire rapidly, but with enough clarity to be understood by all members of the FDC. Regardless of the method of target location, the call for fire will be sent in the three parts shown below.

You will send each part as you determine the information, and, as it is received at the FDC, each part will be read back (repeated to you).

  1. OBSERVER IDENTIFICATION. The FDC identifies you by your call sign. Call signs and frequencies are taken from the Communication Electronic Operating Instructions (CE01). (You will learn more about the CE01 in your communications lessons.) A typical call sign is R5T84. The R5T identifies the radio net that you are assigned to, and the 84 is the station call sign (your station). This is transmitted as ROMEO FIVE TANGO EIGHT FOUR. When making your first contact of the day with the FDC, use your complete call sign as shown below.

Y5A57, THIS IS R5T84, OVER

In later transmissions you may shorten the call sign to just T84. When sending the call for fire, the call sign is used only in the first transmission; afterwards, only the information is sent. All transmissions from you will be followed by the word OVER if you are reading back a transmission; end a transmission with the word OUT.

EXERCISE

Use this call sign, H8Y44, and fill in the blanks of the following statements.

  1. The 44 represents a _____________ call sign.
  2. Call signs are taken from the ______________________.
  3. H8Y represents the ____________ _________.

a. station (your) b. CEOI c. radio net

 

  1. WARNING ORDER. The warning order alerts the FDC and gets them into action. Your warning order will tell the FDC the type mission you want, the number of guns you desire to fire in effect, and how you located the target. Letís look at all these things in more detail.
  2. TYPE OF MISSION:

    ADJUST FIRE (AF). The adjust fire mission is fired with one gun firing one round (one round = one complete primer propellant, projectile and fuze) to move the round to the target. After all the corrections are made, the rest of the guns will fire on the target. This is done so that rounds are not wasted by firing at an inaccurate target location. If you want to fire this type of mission, announce ADJUST FIRE after the observer identification. It should look like this.

    A57, THIS IS T84, ADJUST FIRE

    NOTE: The word OVER was not included because this is not a complete transmission.

    FIRE FOR EFFECT (FFE). Suppress (S) and Immediate Suppression (IS) missions will not be covered in this material.

    METHOD OF TARGET LOCATION. The last part of the warning order is to tell the FDC the method that you used to locate your target. This is done because the FDC must plot the target on the firing chart in the same way that you have determined its location. When you announce the method of location here, the FDC has advance warning and can give you a quicker response to your fire request. There are 3 primary methods of target location. They are polar, shift from a known point, and grid. Whichever method the observer uses will be identified after the observer says "Adjust Fire," ie. "A57 this is T84, adjust fire, polar, overÖA57, this is T84, adjust fire, shift known point 1, over." When a warning order does not specify a method of target location, then it is understood that the grid method has been used.

    A57, THIS IS T84, ADJUST FIRE, OVER

  3. LOCATION OF THE TARGET. In your first transmission, the FDC was given the method of target location (polar, shift from a known point, grid). All information that is necessary to plot the target on the firing chart is now sent in the second transmission in the call for fire. (Remember, the call sign is NOT used here!)
  4. POLAR Ė The observer has located the target with a DIRECTION and a DISTANCE from HIS location. In order for the FDC to plot this target, FDC must know and plot the distance to the nearest 100 meters. If possible, the observer should include the vertical shift. A vertical shift is the difference in meters between the altitude of the target and the altitude of the observerís location. This shift is expressed to the nearest 5 meters, only if it is greater than 30 meters. A call for fire using the polar method would be sent as follows:

    A57, this is T84, adjust fire polar, over. Ö.OBSERVER

    FDCÖ. T84 this is A57, adjust fire polar, out.

    Direction 5670, distance 3800, up 35, over. Ö.OBSERVER

    FDCÖ. Direction 5670, distance 3800, up 35, out.

    GRID. Normally in area fire, a six-place grid is all that is required. Eight-place grids are used for registrations (a mission to correct firing data) or for missions that require more accuracy (a six-place grid is only accurate to 100 meters). The direction is not included because it is not needed to plot the target. Since this is to be an adjust fire mission, send the direction before or with the first correction, not in the call for fire.

    GRID 215562, OVER

    LETíS PRACTICE: You are the observer, and you have spotted two enemy tanks being refueled at a road junction. You have located this road junction on your map and determined the grid to be 915443 (six digits). Use the same call signs from the previous exercise and write your transmissions below.

    First Transmission ______________________________________________________________________

    Second Transmission ____________________________________________________________________

    First: A57, THIS IS T84, ADJUST FIRE, OVER

    Second: GRID 915443, OVER

    If you had problems with either exercise, go back and review before going to the next frame. You may take a break if you wish before continuing.

    From this point on, the remaining elements of the call for fire are the same regardless of the method of target location used. The grid method will be used for the duration of this text.

    ELEMENTS OF THIRD TRANSMISSION

  5. TARGET DESCRIPTION. There are many things that you can tell the FDC that will help them decide the best method of attack on a particular target. Naturally, the FDC would not fire a battalion at one infantry squad. It is up to you to describe the target with enough detail for the FDC to decide the best method of attack. Listed below are a few things to consider.
  6. WHAT THE TARGET IS (troops, equipment, tanks, etc.)

    WHAT THE TARGET IS DOING (digging foxholes, building a bridge, etc.)

    NUMBER OF ELEMENTS (squad, platoon, 2 trucks, 10 tanks, etc.)

    DEGREE OF PROTECTION (in the open, in foxholes, or a concrete bunker, etc.)

    TARGET SIZE AND SHAPE (if it covers an area, give the radius in meters (RADIUS 400).

    If the target is rectangular, give the length and width in meters and the attitude (the azimuth of the longest side less than or equal to 3200 mils, expressed to the nearest 50 mils). For example: 500 by 300, ATTITUDE IS 1550. All of these things we have mentioned may not apply to your target, but should be considered before sending your target description. Look at the following examples:

    INFANTRY PLATOON IN THE OPEN, . . .

    OR

    MACHINEGUN FIRING FROM BUNKER, . . .

    8 TANKS IN AN ASSEMBLY AREA, RADIUS 400, . . .

    BN CP IN TREELINE, 400 BY 50, ATTITUDE 2300, . . .

    As you can see, there is no standard definition for targets or for their size. You must use your judgment in describing the target. The target description and all remaining elements are sent in the third transmission of the call for fire.

  7. METHOD OF ENGAGEMENT. Under this element you may request the type of adjustment, trajectory, ammunition, or the distribution. Letís see exactly what these terms mean and how you can use them.

TYPE OF ADJUSTMENT. There are two types of adjustment employed by the artillery: precision and area. Precision is conducted with only one gun and is fired against a point target; such as, a bunker or even a stalled tank. Precision may be used to correct firing data (a registration) or to destroy a target. A registration is initiated by the FDC and will be covered in a later lesson. You initiate a destruction mission by announcing DESTRUCTION after the target description. This is illustrated below.

MACHINE GUN IN CONCRETE BUNKER, DESTRUCTION OVER

Area adjustment is the standard for the artillery. It is conducted with one gun and after all of the corrections are made, the rest of the battery will fire for effect. This type of adjustment is used to attack a dispersed target as indicated in the target description. You may be required to adjust fire close to friendly troops. If your target is within 600 meters of friendly troops, include the term DANGER CLOSE in your call for fire. This is a warning to the FDC to be extremely careful in the computation of firing data.

TRAJECTORY. This pertains to the path of the projectile in flight (low angle and high angle). Low angle is normally used and does not have to be requested. High angle is used to fire over obstacles such as hills or may be used to fire into enemy trenches. You should include the term HIGH ANGLE after the target description if you want this method. The illustration below will give you a better idea of when to use high angel fire.

AMMUNITION. The standard ammunition used by the artillery is shell HE (High Explosive) and fuze Q (Quick). It will normally be employed in both the adjustment and the fire for effect phases. Do not request shell HE or fuze Q in your call for fire. When requesting a different projectile that is always fired with same type fuze, it is not necessary to request the fuze also. Listed below is a guide that will help you in selecting various combinations.

SHELL HE. This is a high explosive projectile that produces fragmentation. It may be used with the following fuzes:

FUZE Q. This fuze detonates on impace and is used with HE to attack personnel or vehicles, etc. This fuze may also be set for delay for better penetration or ricochet action.

FUZE (TIME) TI. This fuze has a mechanical timer that detonates the shell when the time setting has elapsed. Use it the HE to attack personnel in the open, in trenches, in foxholes, etc. It must be adjusted to a 20 meter height of burst (HOB) above the target for the best effect. Time fuze is not used in high angle fire.

FUZE VT (VARIABLE TIME). This fuze is radio controlled to detonate at a predetermined HOB. It normally detonates at 20 meters above the ground, but may vary depending on the weapon caliber and the angle of fall. It requires no adjustment and is very effective in high angle fire. Use it against the same targets as time fuze.

SHELL WP (WHITE PHOSPHORUS). This projectile scatters burning phosphorus over the target. It can be fired with fuze quick or time to destroy enemy equipment or to start a smoke screen. It may also be detonated in the air to aid in target location or navigation.

SHELL ICM (IMPROVED CONVENTIONAL MUNITION). This projectile spreads high explosive grenades over the targets that explode on impact. It is fired only with time fuze and is the best choice against personnel or light vehicles in the open.

SHELL SMOKE. This projectile is filled with smoke canisters. It is more effective for screening purposes than WP because it lasts longer. It is fired only with time fuze and the direction of the wind must be considered.

SHELL ILLUMINATION. This projectile releases a flare that slowly floats down by parachute to light up the target at night. It is fired only with time fuze and must be adjusted to a proper HOB to provide the best illumination over the target.

VOLUME OF FIRE. You may request the number of rounds per gun to be fired in effect. If the battery is firing in effect and you announce 3 ROUNDS, you will get a total of 18 rounds on the target (from a 6-gun battery). If you requested the battalion (18 guns) in the warning order, announcing 3 ROUNDS here will get a total of 54 rounds.

INFANTRY COMPANY IN OPEN, ICM, 3 ROUNDS, OVER

DISTRIBUTION. You may control the pattern of how the rounds burst around the target. This pattern of bursts is called a sheaf. Unless otherwise requested, the battery will fire a parallel sheaf. In a parallel sheaf, all guns fire the same data, (direction and distance) and the pattern of bursts resembles the position that the guns are in. Shown at right is an example of a parallel sheaf.

NOTE: With an automated FDC (equipped with BCS or BUCS) a circular sheaf will be fired unless another sheaf is requested.

You may request a sheaf of any width, or a converged sheaf by simply stating what you want. Below is an example.

ENEMY RADAR, CONVERGED SHEAF, OVER

EXERCISE

Fill in the blanks of the following statements:

  1. The standard shell/fuze combination is shell __________, fuze __________.
  2. The best trajectory to fire at a target on the reverse side (backside) of a hill is __________ _________.
  3. If your target is within 600 meters of friendly troops, you would include __________ __________ in the call for fire.
  4. The radio controlled VT fuze causes the projectile to burst about __________ meters above the ground.
  5. When all guns fire the same data, the rounds will burst in a __________ sheaf.

1. HE, Q 2. High Angle 3. Danger Close 4. 20 or 7 5. Parallel

  1. METHOD OF FIRE AND CONTROL. In area fire, the adjustment is normally conducted with one of
  2. the center guns of the battery. If for any reason you decide that another gun would be more appropriate, request it in this element. You may request that the guns be fired in a certain order or at a time interval. The normal time interval is 5 seconds. If you want a different interval you must specify it. The time of firing may be controlled by announcing:

    AT MY COMMAND, OVER

    When the guns are ready to fire, the FDC will announce:

    BATTERY (OR BATTALION) IS READY, OVER

    NOTE: Automated FDCs have the ability to be more accurate in determining firing data. Therefore all pieces can alternate in adjustment rather than only the center platoon.

    After this is announced, you must give the command to fire. AT MY COMMAND remains in effect until you announce:

    CANCEL AT MY COMMAND, OVER

    You may tell the FDC when you want the rounds to impact by announcing:

    TIME ON TARGET 0910, OVER

    TIME ON TARGET 20 MINUTES FROM . . . . (NOW), OVER

    IF YOU DO NOT ANNOUNCE ANY METHOD OF CONTROL THE GUNS WILL FIRE WHEN THEY ARE READY!!

  3. CHALLENGE AND REPLY. Challenge and reply is not part of a call for fire, but it is a vital procedure. The purpose of this is to ensure that fire requests are from friendly observers. The FDC will insert the challenge in the last readback of your call for fire. You must give the authentication within 15 to 20 seconds. Replies not within this time are suspicious and are basis for rechallenge. Subsequent adjustment of fire or immediate engagement of additional targets will not normally require continued authentication. (You will learn more about this system in your communication lessons.)
  4. MESSAGE TO OBSERVER. After the FDC receives your call for fire, the FDO (Fire Direction

Officer) will make the final decision on how to attack the target. His decision will be announced to you in the Message to Observer. The message consists of the three items shown below.

UNITS TO FIRE. The battery or batteries that will fire the mission. Units in the MTO are identified by the letter in their abbreviated call sign. If the battalion is firing in effect in an adjust fire mission, the adjusting battery will be specified. Call signs: Battalion T5W40 and Btry is A4M99. An MTO with A Btry adjusting would begin with M. If battalion was firing for effect and A Btry adjusting, then the MTO would begin with W,M.

CHANGES TO THE CALL FOR FIRE. Any changes made to what you requested; such as a different projectile of fuze.

NUMBER OF ROUNDS. The number of rounds per gun to be fired in effect. This may be an increase or decrease from what you requested.

TARGET NUMBER. Assigned to each mission to facilitate processing of subsequent corrections.

Below is a partial call for fire showing the Authentication and the Message to Observer. Call signs from the previous page are in effect.

OBSERVERFDC

 

 

INFANTRY PLATOON IN THE OPEN, VT IN EFFECT, OVER

 

 

INFANTRY PLATOON IN THE OPEN, VT IN EFFECT, AUTHENTICATE PAPA BRAVO, OVER.

I AUTHENTICATE CHARLIE, OUT

 

 

Message to Observer

 

 

 

MIKE, 2 ROUNDS, TGT BF7001, OVER.

MIKE, 2 ROUNDS, TGT BF7001, OUT

 

In the previous example we can see that the FDC agreed with the request for VT fuze and decided to fire two volleys at the target. In the example below, shell ICM was requested, but the FDO changed this to shell HE, fuze VT with the battalion firing 3 rounds in effect.

OBSERVER

FDC

 

 

INFANTRY COMPANY IN OPEN, ICM, OVER

 

 

INFANTRY COMPANY IN OPEN, ICM, AUTHENTICATE TANGO FOXTROT, OVER

I AUTHENTICATE ECHO, OUT

 

 

Message to Observer

 

 

 

WHISKEY, VT, 3 ROUNDS, TGT BF7002, OVER.

WHISKEY, VT 3 ROUNDS, TGT BF7002, OUT.

 

 

 

 

 

 

EXERCISE

Use the partial call for fire below to answer the questions.

OBSERVER

FDC

 

 

ENEMY OP IN THE OPEN, VT IN EFFECT, OVER.

 

 

ENEMY OP IN THE OPEN, VT IN EFFECT, OUT.

BRAVO, ICM, IN EFFECT, OUT.

 

 

BRAVO, ICM, IN EFFECT, OVER

  1. What projectile and fuze has been requested by the observer?
  2. Projectile __________________

    Fuze ______________________

  3. What projectile and fuze will be fired in effect?
  4. Projectile __________________

    Fuze ______________________

  5. What size element will fire in effect? _____________________________________
  1. CORRECTIONS. Errors are sometimes made during your transmission or by the FDC in reading back the information. If you realize that an error has been made, announce CORRECTION and then transmit the correct information. Look at the examples below.
  1. You have transmitted:
  2. DIRECTION 1600, DISTANCE 2500, OVER.

    And you realize that you should have sent direction 1800. You should announce:

    CORRECTION, DIRECTION 1800, DISTANCE 2500, OVER.

  3. You have transmitted:

LEFT 200, ADD 400, OVER.

The FDC reads back:

LEFT 200, DROP 400, OVER.

You should then announce:

CORRECTION, LEFT 200, ADD 400, OVER.

 

ADJUST AREA FIRE USING SUCCESSIVE BRACKETING PROCEDURES

INSTRUCTIONS

This lesson is divided into five subtasks. Work through each subtask in order and follow the instructions with each subtask. You should make sure that you can successfully complete a subtask before you continue to the next one.

SUBTASK 1. DETERMINING OBSERVER SPOTTINGS

  1. As an observer, each time you see a round burst you should make spottings for range, deviation, and, in time for fire, for height of burst. (We will not discuss height-of-burst spottings in this lesson. Spottings are made in their order of difficulty. The order of difficulty of spottings is range, then deviation. An explanation of each of these types of spottings is as follows:
  1. RANGE. Whether the burst is over (beyond), short of, or at the same distance as the target.
  2. DEVIATION. The number of mils the round bursts to the left for right of the target.

Now, complete the statements below by filling in the blanks.

  1. The type of spotting made to determine how far left or right of the target a round bursts is __________.
  2. The type of spotting made to determine whether a burst is over, short of, or at the same distance as a target is ________________.

ANSWERS

  1. Deviation b. Range

Letís take these two types of spottings and discuss them separately. Weíll start with range since it is highest in the order of difficulty.

  1. As we have said, a range spotting is simply a determination of whether a burst was over, short of, or at the same distance as the target. This determination is made in relation to the distance from your (observer) location to the target. Here are the types of range spottings you may make in area adjustment fire with a short definition of each.
  1. OVER. This means the round has burst over, or beyond the target.
  2. SHORT. This means the round has burst short, or between you and the target.
  3. TARGET. This means the round actually hit the target (used only in precision fire).
  4. RANGE CORRECT. This means the round has burst at the same distance as the target.
  5. DOUBTFUL. This means you can see the burst but you are not sure whether it is OVER, SHORT, TARGET, OR RANGE CORRECT.
  6. LOST. This means you cannot determine the burst location by sight or sound.
  7. UNOBSERVED. This means you did not see the round burst, and you cannot determine whether it was OVER or SHORT.
  8. UNOBSERVED OVER (SHORT). You can tell that the round burst OVER or SHORT of the target, but you canít tell exactly where. This means you did not see the round burst, but you can tell that it was OVER or SHORT.
  1. Of all the types of range spottings you may observe, only three of them are considered DEFINITE spottings. That means you can definitely tell where they burst, The three types of range spottings that are considered definite range spottings are OVER, SHORT, and RANGE CORRECT.
  2. The next type of spotting you will made is the DEVIATION spotting. This is simply a determination of whether the burst was left or right of the target and how far. Deviation spottings are made in relation to the OT (Observer-Target) line. This is an imaginary line from the observer to, or through, the target.

There are three types of observer deviation spottings. Here they are with a short definition of each:

    1. LEFT: The round bursts to the left of the target (or OT line).
    2. RIGHT: The round bursts to the right of the target (or OT line).
    3. LINE: The round bursts along (on) the OT line.

Read the statements below and indicate whether they are TRUE or FALSE by circling the appropriate T or F.

    1. T Ė F. A deviation spotting of LINE means the round has burst to the left or right of the target.
    2. T Ė F. A deviation spotting of RIGHT means the round has burst to the right of the target (or OT line).
    3. T Ė F. The three types of deviation spottings are LEFT, RIGHT, and LINE.

ANSWERS: a. F b. T c. T

  1. When you spot a burst as being LEFT or RIGHT you must measure, in mils, how far LEFT or RIGHT the burst is. These measurements are made to the nearest 5 mils. There are several methods used to make deviation measurements, but we will use only the binocular reticle pattern method in this lesson. The horizontal scale of the binocular reticle pattern is used to make deviation measurements.
  2. REMEMBER:
  1. The three types of definite range spottings are OVER, SHORT, and RANGE CORRECT.
  2. The three types of deviation spottings are LEFT, RIGHT, and LINE.
  3. Deviation spottings are measured in mils to the nearest 5 mils.
  1. The range and deviation spottings are simply an observerís mental note of where a round bursts in relation to a target. Until you have experience at making these spottings, you may want to write them down or say them aloud. But, practice them in your mind.

SUBTASK 2. DETERMINE THE OT FACTOR

The OT factor, or Observer-to-Target factor, is a value used to convert observer deviation spottings that are measured in mils, to deviation corrections in meters. Before you can determine an OT factor, you must first determine the distance, in meters, from your observer location to the target. You can measure that distance from a map or you can estimate accurate OT distances.

Now, letís look at how you, as an observer, convert OT distances to OT factors.

  1. When the OT distance is greater than 1000 meters, first express that distance to the nearest 1000 meters, then divide this distance by 1000. That will give you the OT factor.
  2. Here is an example:

    OT distance = 3700 meters

    Rounded to nearest thousand = 4000 meters

    Divided by 1000 = 4000/1000

    OT factor = 4

    In the example above, we underline the key steps to determining the OT factor when the OT distance is greater than 1000 meters.

    Okay, now try some on your own. Complete the problems below by filling in the blanks, then check your answers.

    a. OT distance = 1800 meters

    Expressed to nearest thousand = _____ meters

    Divided by 1000 = _____/1000

    OT factor = _____

    b. OT distance = 4300 meters

    Expressed to nearest thousand = _____ meters

    Divided by 1000 = _____/1000

    OT factor = _____

    ANSWERS.

    a. OT distance = 1800 meters

    Expressed to nearest thousand = 2000 meters

    Divided by 1000 = 2000/1000

    OT factor = 2

    b. OT distance = 4300 meters

    Expressed to nearest thousand = 4000 meters

    Divided by 1000 = 4000/1000

    OT factor = 4

  3. When the OT distance is less than 1000 meters, we use basically the same procedures to determine the OT factor. The only differences are: we round the distance to the nearest 100 meters instead of the nearest 1000 meters, and we express the OT factor as a decimal.

Here is an example:

OT distance = 860 meters

Rounded to nearest hundred meters = 900 meters

Divided by 1000 = 900/1000

OT factor (Expressed as a decimal) = .9

Now, hereís one for you to do:

The OT distance is estimated to be 930 meters. Circle the letter of the correct OT factor.

    1. 9/10
    2. 9
    3. .9
    4. 1

Answer. C. .9

  1. How do you express an OT distance that is exactly half-way between two other distances?

Letís answer that by looking at the "Artillery Round-Off Rule."

"TO EXPRESS A NUMBER THAT IS EXACTLY HALF-WAY BETWEEN TWO NUMBERS, ROUND IT TO THE EVEN NUMBER."

Here are some examples:

Once you have your OT distance rounded-off, compute your OT factor.

Express the OT distances below, then determine the OT factor for each distance. Write your answers in the spaces provided.

OT DISTANCE ROUNDED-OFF OT FACTOR

a. 1500 __________ __________

b. 650 __________ __________

c. 4500 __________ __________

ANSWERS. ROUNDED-OFF OT FACTOR

a. 2000 2

b. 600 .6

c. 4000 4

  1. Remember these basic steps for determining the OT factor:
    1. When the OT distance is greater than 1000 meters:
    1. When the OT distance is less than 1000 meters:
    1. When the OT distance is exactly half-way between two distances:

Okay, letís see how well you have paid attention. Determine the OT factors for each of the OT distances listed below.

OT DISTANCE OT FACTOR

a. 2800 __________

b. 3200 __________

c. 830 __________

  1. d. 3500 __________
  2. e. 2300 __________
  3. f. 1500 __________
  4. g. 3700 __________
  5. h. 950 __________
  6. ANSWERS.
      1. 3
      2. 3
      3. .8
      4. 4
      5. 2
      6. 2
      7. 4
      8. 1

SUBTASK 3. DETERMINING OBSERVER DEVIATION CORRECTIONS

After an observer sees a round burst and makes his mental spotting of where the burst occurred in relation to the target and the OT line, he must start to make corrections to adjust the subsequent rounds to the target. Since observer corrections are sent in the reverse order from which spottings are made, weíll discuss deviation corrections first.

  1. In the two previous subtasks, you learned how to measure deviation spottings in mils and how to determine an OT factor. Do you recall how to do each of these? Letís find out.
  1. The estimated OT distance is 1200 meters. What is the OT factor for this distance? _________________.

ANSWER

a. 1 OT distance = 1200

Expressed as = 1000

Divided by 1000 = 1000/1000

OT Factor = 1

  1. When you send a deviation correction to the Fire Direction Center, which weíll call the FDC, you simply tell them the direction and distance, in meters, that the burst needs to be moved to bring it in line with the target or OT line.
  2. If you spot a burst as being LEFT of the target, doesnít it make sense that you must correct it to the RIGHT to bring it in line with the target or OT line? Sure it does. And if you spot a burst as RIGHT, arenít you going to correct to the LEFT? You bet you are.
  3. Obviously, a spotting of LINE needs no deviation correction.

  4. To convert your deviation spotting measurement in mils to a deviation correction in meters, multiply the OT factor times the number of mils in your spotting. Here is an example:

Our OT factor is 3 and our deviation spotting is 20 RIGHT.

3 x 20 = 60 meters

Deviation corrections are sent to the nearest 10 meters and corrections of 20 meters or less should not be sent during the adjustment phase. Hereís another example:

OT distance = 2500

SPOTTING 25 RIGHT

CORRECTION LEFT 50

We multiplied the OT factor of 2, times the number of mils we measured, and corrected toward the target.

EXERCISE

Determine the deviation corrections for each of the deviation spottings listed below. You are given the OT distance for each spotting. Write your answers in the spaces provided. If there is no correction needed, write the word NONE in the blank for that correction.

SPOTTING OT DISTANCE CORRECTIONS

a. 25 LEFT 4000 _________________________

b. 40 RIGHT 2500 _________________________

c. 20 RIGHT 3400 _________________________

d. 50 LEFT 1500 _________________________

e. 40 LEFT 930 _________________________

f. 15 RIGHT 1300 _________________________

ANSWERS.

    1. RIGHT 100
    2. LEFT 80
    3. LEFT 60
    4. RIGHT 100
    5. RIGHT 40
    6. NONE (Less than 20 meters)

SUBTASK 4. DETERMINING OBSERVER RANGE CORRECTIONS

One of the most difficult corrections for an observer to make is the range correction. This is because it is normally not possible to measure the distance a round misses a target in range. Only experience and a good knowledge of the terrain in a target area can help an observer estimate range corrections accurately. So, a technique called successive bracketing is used to make observer range corrections.

  1. Successive bracketing is when an observer establishes a range bracket with positive spottings of one round OVER the target and another SHORT of the target, then, with following rounds, keeps curting the size of that bracket in half, getting closer to the target each time.

Recall that in a previous subtask we said you must get a definite range spotting before you can begin your range adjustment. Do you remember what the three types of definite range spottings are?

  1. ____________
  2. ____________
  3. ____________

ANSWERS.

  1. OVER
  2. SHORT
  3. RANGE CORRECT
  1. After you get your first definite range spotting, you estimate the distance the round missed the target (in range), then send the FDC a correction that will cause the next round to burst on the opposite side of the target (in range). Range corrections are sent to the FDC as ADD or DROP, so many meters. If your initial round bursts over the target, send a DROP correction in meters, that will cause the next round to be SHORT of the target. If your initial round is SHORT of the target, send an ADD correction that will cause the next round to be OVER the target. Complete this statement by filling in the blanks.
  2. Range correction is sent to the FDC in meters as ______________________ or __________________.

    ANSWERS. ADD or DROP

  3. As we said, estimating the distance a round misses the target in range is normally hard to do. But, estimate the distance the best you can, then start establishing your initial range bracket.

Here are some "rules of thumb" to help you establish an initial bracket.

  1. OVER/SHORT more than 400 meters but less than 800 meters, ADD/DROP 800 meters.
  2. OVER/SHORT more than 200 meters but less than 400 meters, ADD/DROP 400 meters.
  3. OVER/SHORT more than 100 meters but less than 200 meters, ADD/DROP 200 meters.

If you donít establish a bracket with your first correction, estimate how far the second round misses the target and try again to establish an initial bracket.

  1. Once you have established your initial range bracket, simply start splitting that bracket in half, correcting in the opposite direction each time. You should now see why we make range corrections in multiples of even 100ís (200, 400, 800). It certainly makes splitting the brackets easier. Hereís what the range corrections for a series of rounds might look like:

Round 1 = ADD 800

Round 2 = DROP 400

Round 3 = ADD 200

Round 4 = DROP 100

Keep splitting the range brackets until you split a 100 meter bracket or you get a spotting of range correct. You spotted your initial round as OVER the target about 300 meters and sent a correction of DROP 400 to the FDC. Round 2 bursts SHORT of the target. Circle the latter of the correction you would send to the FDC for round 2, then check your answer.

  1. ADD 100
  2. ADD 300
  3. ADD 200
  4. DROP 400

ANSWERS.

c. ADD 200 You established a bracket between the initial round and round 2 with the DROP 400 correction. Split the bracket in half and send ADD 200.

SUBTASK 5. FIRE FOR EFFECT, REFINEMENT, AND SURVEILLANCE

The entire purpose for adjusting fire on a target is to accurately mass the fires of an artillery unit so as to destroy or neutralize that target. When an observer has made deviation corrections to bring the rounds in line with the target and has either split the 100-meter range bracket or obtained a range correct spotting, he requests the artillery unit to FIRE FOR EFFECT. The observer must watch the fire for effect and evaluate how effective these massed rounds were. He must then end the mission or make refinement corrections to allow more accurate fire to be placed on the target.

  1. Knowing when to enter fire for effect, which weíll refer to as FFE, is a relatively simple matter. Recall that we made deviation corrections until we bring the rounds in line with the target and we continue the successive bracketing until we either split a 100-meter range bracket or obtain a range correct spotting. When we have met those requirements, we enter FFE. To do that, we make our final range and/or deviation corrections and tell the FDC to fire for effect. If we have no final range and/or deviation corrections, we simply tell the FDC to fire for effect. Here are a couple of examples of how we tell the FDC to enter FFE:
  2. "ADD 50, FFE" "FFE"

    Now, look at the list of observer corrections shown here. These corrections are for a series of rounds with which an observer has been adjusting fire on a target.

    Round 1 = RIGHT 60, ADD 800

    Round 2 = LEFT 30, DROP 400

    Round 3 = ADD 200

    Round 4 = DROP 100

  3. The number of rounds you see bursting in FFE will depend on the type of artillery unit for which you are adjusting and on the nature of the target on which you are adjusting. Some targets require more fire to destroy or neutralize than others. Normally, a Field Artillery battery consists of four to eight weapons. The more rounds you get, the greater the probability of neutralizing the target. Donít expect to see your FFE rounds all grouped right on top of the target. Because of the way artillery units tactically disperse their weapons and because this is area fire, your rounds will probably cover a large area around the target.
  4. After your fire for effect rounds burst, you should analyze the result of the fire, then take whatever action is necessary to complete the mission. Here is what some of those actions might be:

If you feel the fires were accurate and sufficient, tell the FDC to end the mission, then report the effect the fire had on the target. Reporting the effect of fires is called SURVEILLANCE. For example:

END OF MISSION, ESTIMATE 20 CASUALTIES, REMAINDER DISPERSED.

If you feel the fire was accurate but insufficient, tell the FDC to REPEAT and they will fire more rounds. If your rounds were inaccurate but sufficient to neutralize the target, make whatever minor range or deviation corrections that would cause another group of rounds to have more effect on the target, then end the mission and report the surveillance. Making minor corrections after FFE is called making REFINEMENTS. Refinement corrections are measured from the center of the sheaf (group of bursts). Hereís an exampe of ending a mission with refinement corrections.

RIGHT 10, ADD 20, END OF MISSION, ESTIMATE 5 CASUALTIES, REMAINDER DISPERSED.

If you feel the rounds were inaccurate and insufficient, make whatever refinement corrections are necessary and ask the FDC to fire more rounds. For example:

LEFT 20, DROP 50, REPEAT.

Now match the actions you would take in column B with the results of FFE in column A. Write the number of your selection in the spaces provided, then check your answers.

COLUMN A

(RESULTS OF FFE)

COLUMN B

(YOUR ACTIONS)

 

 

_____a. Accurate and sufficient.

1. Make refinement correction and request repeat.

_____b. Inaccurate and sufficient.

2. Request repeat.

_____c. Accurate and insufficient.

3. End the mission and report the surveillance.

_____d. Inaccurate and insufficient.

4. Make refinements, end the mission and report the surveillance.

 

 

 

 

ANSWERS

a. 3 b. 4 c. 2 d. 1