ATP-3-09-02 Field Artillery Survey Download
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Chapter 3 3-2 ATP 3-09.02 16 February 2016 VARIATIONS IN STARTING CONTROL 3-6. Starting control for FA survey consists of the coordinates and height of a SCP and a starting azimuth. Although there are several ways in which starting control can be obtained, the best control available for the area should be used to begin a survey. The variations of starting control can be grouped into three general categories: Known coordinates, height, and azimuth. Assumed coordinates, height and known azimuth. Assumed coordinates, height, and azimuth. KNOWN COORDINATES, HEIGHT, AND AZIMUTH 3-7. Starting control for which the station data are known may be points established by survey done by a higher echelon, or it may be confirmed data established before the start of military operations. Data for stations established by technical engineer specialists, geodetic survey sections, and data for survey control established before the start of military operations are in trigonometric lists prepared and published by the National Geospatial-Intelligence Agency (NGA). ASSUMED COORDINATES AND HEIGHT AND CORRECT GRID AZIMUTH 3-8. When survey control is not available in the area, the coordinates and height of the starting station must be assumed. Correct grid azimuth can be determined by using the IPADS or IPADS-G. Correct grid azimuth should always be used whenever possible. If both higher and lower survey echelons initiate surveys by using correct grid azimuths, any discrepancy between surveys that is due to assumption of coordinates will be constant for all points located. The approximate coordinates and height of the starting point can be determined from a large-scale map and should closely approximate the correct coordinates and height to facilitate operations. Starting data determined from a map must always be considered as assumed data. ASSUMED COORDINATES, HEIGHT, AND ASSUMED AZIMUTH 3-9. Assumed azimuth should be used for a starting azimuth only when azimuth cannot be determined from the IPADS, astronomic observation computation, or a published trigonometric list. The assumed azimuth should approximate the correct grid azimuth as closely as possible. The approximate grid azimuth can be determined by using a declinated compass or scaling from a large-scale map (map spot). If either a higher or lower survey echelon or both initiate survey operations with assumed azimuths, differences of varying magnitude will exist between the coordinates of points located by their surveys. This variation complicates the problem of conversion to common control. For this reason, an assumed azimuth should never be used if the correct azimuth can be determined. CONVERSION TO COMMON GRID 3-10. A battalion SCP is a point provided by a higher survey echelon for initiating survey control for the battalion. More than one of these points may be required for a battalion. SCPs on the grid of the next higher echelon may be available in the form of one or more trigonometric points in the vicinity of the battalion installations. When available, trigonometric points from NGA or other published trigonometric lists should be used as the basis for all echelons of survey operations. When one or more SCPs have been established by the next higher echelon, these SCPs should be used as the basis for battalion survey operations. In either situation, the common grid is established. 3-11. Unless the tactical situation causes the commander to decide otherwise, battalion (battery) data are converted to the grid of the next higher echelon when data differ by 2 mils or more in azimuth, 10 meters or more in radial error, or 2 meters or more in height. If the next higher echelon converts its survey control to a different grid, the battalion must also convert to that grid. The problem of converting data to a common grid is greatly simplified if survey personnel use the correct grid azimuth to initiate survey operations. Accurate azimuth can be determined by IPADS or IPADS-G.