DA Form 5599-R: True to Grid Azimuth (BUCS) | Download

DA Form 5599-R: True to Grid Azimuth (BUCS) | Download – DA Form 5599-R: Computation – Convergence of True Azimuth to Grid Azimuth (BUCS)(LRA) is a specialized U.S. Army form used in field artillery survey operations to convert true (gyroscopic or astronomic) azimuth to grid azimuth using the Backup Computer System (BUCS) or equivalent tools.

This form supports precise artillery fire support by ensuring accurate directional data on the Universal Transverse Mercator (UTM) grid system. It remains relevant for training, contingency operations, and units maintaining proficiency in manual or semi-automated survey techniques, even as modern systems like IPADS evolve.

Why Grid Convergence Matters in Army Surveying?

True azimuth (from gyroscopic instruments or astronomic observations like Polaris) references geodetic true north. Grid azimuth aligns with the flat UTM grid north on maps. The angular difference is grid convergence (also called mapping angle or convergence angle).

Convergence depends on latitude, longitude, and position relative to the UTM zone’s central meridian:

  • Positive (add) west of the central meridian (Northern Hemisphere).
  • Negative (subtract) east of it.
  • Signs reverse in the Southern Hemisphere.

Failing to apply this correction properly can lead to significant errors in targeting, especially at longer ranges. DA Form 5599-R standardizes this computation for accuracy and documentation.

Key Details of DA Form 5599-R

  • Full Title: Computation – Convergence of True Azimuth to Grid Azimuth (BUCS)(LRA).
  • Date: December 1986 (with updates/revisions like SEP 96 references in some versions).
  • Proponent: U.S. Army Training and Doctrine Command (TRADOC), referenced in FM 6-2 (Field Artillery Survey).
  • Purpose: Records up to four convergence computations per sheet. Includes fields for administrative data, station names, geographic coordinates, true azimuth, grid zone, computed convergence, and resulting grid azimuth.
  • Related Tools: Primarily used with BUCS Program 9 (Grid Convergence). Alternatives include nomographs in FM 6-300 (Table 6a) for quicker approximations.

Required Input Fields (typical):

  • Name of Azimuth Mark
  • Name of Occupied Station (Occ Sta)
  • Latitude (N/S)
  • Longitude (E/W)
  • True Azimuth (in mils)
  • Grid Zone

Outputs:

  • Convergence (mils)
  • Grid Azimuth (mils)

Step-by-Step: How to Use DA Form 5599-R with BUCS?

  1. Prepare: Gather gyroscopic true azimuth, precise geographic coordinates of the occupied station, and grid zone.
  2. Access Program: On BUCS, select SURVEY CALC (option B) → GRID CONVERGENCE (option K).
  3. Enter Data: Input station details, latitude/longitude, true azimuth, and grid zone into the required fields.
  4. Compute: The system calculates convergence and grid azimuth. Record results on the form.
  5. Verify: Have a checker review; document in remarks/notebook reference.
  6. Apply: Grid Azimuth = True Azimuth ± Convergence (sign per rules).

Pro Tip: Four computations fit per form, making it efficient for survey teams establishing multiple lines or control points.

Context in Modern Field Artillery Survey

While digital systems like the Improved Position and Azimuth Determining System (IPADS) or GPS reduce manual computations, DA Form 5599-R supports:

  • Backup/manual procedures.
  • Training (e.g., MOS 13T Field Artillery Surveyor).
  • Gyroscopic azimuth determination (e.g., with north-seeking gyroscopes).
  • Integration with PADS and conventional methods for common survey control.

Accurate azimuth conversion enables massed fires, surprise effects, and reliable target handoff across units.

Download DA Form 5599-R

You can find fillable or printable versions on official Army sites, armyreal.com, or through unit resources/FM 6-2 appendices. Always use the most current version from authenticated sources like armypubs.army.mil for operations.

Search Tip: “DA Form 5599-R PDF” or reference FM 6-2 for blank reproducible copies.

Best Practices and Training Tips (for U.S. Army Personnel)

  • Double-check coordinates and grid zone — small errors amplify over distance.
  • Understand LARS (Left Add, Right Subtract) or similar rules for azimuth conversions.
  • Combine with other DA forms like 5590-R (coordinates/azimuth from points) or 5598-R (Polaris azimuth).
  • Maintain proficiency: Convergence is foundational for fourth- and fifth-order survey accuracy.
  • Reference current ATPs/FMs for updates, as technology evolves but core principles endure.

Mastering DA Form 5599-R ensures reliable directional control whether in high-tech or degraded environments. It exemplifies the precision demanded in U.S. Army field artillery.

For official guidance, consult FM 6-2 Field Artillery Survey, ATP 3-09.02, or your unit’s survey SOPs. Train hard, stay accurate—lives and mission success depend on it.