Geospatial Information Agency of Indonesia (BIG) has issued a policy that a map projection that should be used in geospatial data processing system is Universal Transverse Mercator (UTM). Based PMNA/KaBPN No. 3 of 1997, BPN using Transverse Mercator 3� projection system (TM-3�) for measuring and mapping land parcels. Therefore, the purpose in this research are 1) to know how large and vast differences in distortion, direction, and angle generated in UTM
projection system and TM-3�, 2) to know the pattern of distortion that occurs in the UTM and TM-3�?
The method used is the comparative experiment method (experiment by comparison) with a quantitative approach. The analysis is vast difference test with constant tolerance of 0.5% and direct comparison of the value of convergence grid and angle correction value. Vast difference is vast difference plots were counted in 2 (two) different projection field. In calculating the difference in area, vast areas of land on the surface of the ellipsoid used as a reference comparator and an area that is closer to the correct value.
Based on the research result and analysis, it is found that 1) there is no real difference between the vast area of the UTM projection and TM-3� projection with extensive distortion values generated in UTM projection system is -0.08% in
the surrounding area central meridian and 0.139% for the area around the edge of the meridian, while the TM-3� projection system is -0.02% around the central meridian and 0.035% for the area around the edge of the meridian, 2) the distortion direction and angle of a point on the UTM projection is worth twice that of distortion direction and angle of a point on the TM-3� projection with the maximum value of distortion direction in UTM projection system is 34' 19.743" and the TM-3� projection system is 17' 10.244", while the value of the largest angle distortion in UTM projection system is -1.572" and the TM-3� projection system is -0.785", 3) extensive distortion pattern that occurs in UTM projection system and TM-3� projection in one zone is the same that form the graphic basins facing upwards, with the difference between them is the difference in terms of percentage ranges, while the pattern of change in the direction and angle distortion on both the projection system is same.

Keywords : Projection system, Distortion, UTM, TM-3�.