ATP-3-09-30 Observed Fires Download
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Chapter 5 5-6 ATP 3-09.30 28 September 2017 Table 5-1. Determination of deviation corrections OT RANGE (METERS) OT FACTOR SPOTTING DEVIATION CORRECTION 4,000 4 45R LEFT 180 2,500 2 100L RIGHT 200 3,400 3 55L RIGHT 160 1,500 2 20R LEFT 40 700 0.7 45L RIGHT 30 Legend. L—left OT—observer-target R—right Note. Table 5-1 expresses 1,500 and 2,500 meters to the nearest even OT factor in order to maintain a common standard of expression. For example, an OT range of 3,500 meters will round up so that the OT Factor is 4, but if the OT range was 3,400 then the OT Factor would be 3. 5-18. If angle T is 500 mils or greater, the FDC should tell the observer. If the observer is told that angle T is 500 mils or greater, continue to use the observer-target factor to make the initial deviation correction. If the observer is getting more of a correction than asked for, the observer should consider cutting the corrections to better adjust rounds onto the target. When the guns are firing, the rounds will land in an elliptical shape pattern along the gun-target line. When angle T is in effect this may result in greater than expected deviation correction. To counteract this, an inexperienced observer should generally cut corrections by half to bring rounds on to the target. A more experienced observer will be able to cut the corrections as needed to move the rounds on to the target. RANGE CORRECTION 5-19. When making a range correction, the observer attempts to "add" or "drop" the adjusting round, along the observer-target line, from a previous burst to the target. If the spotting was SHORT, the observer will “add”; if the spotting was OVER, the observer will “drop”. The observer must be aggressive in the adjustment phase of an adjust fire mission, and must use every opportunity to shorten that phase. The observer should make every effort to correct the initial round onto the target and enter fire for effect as soon as possible. Use successive bracketing procedures only when time is not critical. When conducting an adjustment onto a target, the observer may choose to establish a range bracket. HEIGHT OF BURST CORRECTION 5-20. Figure 5-4 shows height of burst corrections. 5-21. Use one gun in adjusting fuze time. The observer adjusts HOB (after a 100 meter range bracket has been established by using fuze quick) to obtain a 20 meter HOB in fire for effect. This is done by announcing a correction of UP or DOWN (so many meters). 5-22. If the spotting of the initial round is GRAZE, an automatic correction of UP 40 is sent. If the round is an airburst, the HOB of the round (in meters) is computed (HOB spotting in mils above the adjusting point multiplied by the observer-target factor). The appropriate HOB correction is given (to the nearest 5 meters) to obtain the desired 20 meter HOB. 5-23. Enter the fire for effect phase only when a correct HOB is reasonably assured. Therefore, do not begin the fire for effect phase when the spotting for the previous round GRAZE or the HOB correction is greater than 40 meters. If the spotting for the initial rounds in fire for effect is MIXED, the subsequent surveillance report normally includes the correction UP 20.