FM-3-09 Fire Support and Field Artillery Operations Download
Page 203 of 256
Denied, Degraded and Disrupted Operations 30 April 2020 FM 3-09 C-11 ACCURATE COMPUTATIONAL PROCEDURES C-61. The computation of firing data similarly affects all indirect fire systems, to include mortars, and must be accurate. Accurate computational procedures are provided by all FDCs. Automated and manual techniques are designed to achieve accurate and timely delivery of fire. The balance between accuracy, speed, and the other requirements for accurate fire should be included in the computational procedures. C-62. In order to reduce firing incidents is to recognize that individuals make errors, and the best safeguard against those errors is an independent double check of all operations in which human error could cause a firing incident (sometimes referred to as the two man rule). A fundamental aspect of safety is that no one person performs a critical live fire task then checks that task alone. For every critical task required for firing artillery safely, there is a person or persons designated to verify the task. Verification of data includes independent checks including: C-63. Independent checks are performed on each howitzer by the section chief to verify lay of the howitzer, emplaced retaining pins, prefire checks, charges, fuze settings, and set deflection and quadrant, as well as ensuring the announced firing data is applied as announced. C-64. Independent checks are also performed in the FDC where the database must be verified, either as the information is input or as a total review once the entire database has been constructed. The checks are continuous since the FDC must verify any additions, changes, or deletions to the database as they occur. C-65. A means to assist rapid transmission of commands to the howitzers are terrain gun position corrections. Terrain gun position corrections are individual howitzer corrections applied to the gunner's aid on the panoramic telescope (pantel), the correction counter on the range quadrant, and the fuze setting of each howitzer (TC 3-09.81). The digital link between the AFATDS and the howitzer will at some point fail to function. The problem may be in the AFATDS, one or more of the Gun Display Unit Replacement (referred to as a GDU-R), section chief display, or the communications link. When the failure occurs, voice fire commands must be transmitted to one or more of the howitzers. If the failure is at the AFATDS, voice commands must be transmitted to each of the howitzers. It is important that terrain gun position corrections be computed. These corrections, as a minimum, should be computed for the primary, left, and right sectors. C-66. During some types of degraded howitzer operations, the battery or platoon FDC may assume direct control of technical fire direction and send firing data to the howitzer. For example, if the digital control system of an individual howitzer section is degraded or inoperative, the FDC may compute technical firing data for that section. The preferred method requires an operational howitzer to locate next to the degraded howitzer and the degraded howitzer uses the operational howitzer's firing data. For detailed procedures refer to appropriate technical manual for the cannon system and ATP 3-09.50. C-67. Manual backup should be established as a form of "position improvement" and should not impede setup or processing with automated means. The manual backup also serves as a basis of a rapid independent check to the automated solution. One of the elements to the solution of the gunnery problem is the determination of chart data. Chart data consists of chart range, chart deflection, and angle T. The determination of chart data requires the construction and operation of a firing chart. SECTION IV – FIRING CHARTS C-68. A firing chart is a graphic representation of a portion of the earth's surface used for determining distance (or range) and direction (azimuth or deflection) (TC 3-09.81). The chart may be constructed by using a map, a photomap, a grid sheet, or other material on which the relative locations of batteries, known points, targets, and observers can be plotted. Additional positions, fire support coordinating measures, and other data needed for the safe and accurate conduct of fire may also be recorded. C-69. A surveyed firing chart is a chart on which the location of all required points (battery or platoon positions, known points, and observation points) are plotted (TC 3-09.81). These locations can be based on survey or map inspection. All plotted points are in correct relation to one another and reflect actual map coordinates. C-70. Chart data consist of chart range and chart deflection from the firing unit to the target and angle T. In a manual FDC, two firing charts will be constructed and used to check each other.