The estimation of positional errors always is a challenge for geographers and land surveyors. While the algorithms for transforming coordinates are existed a long time ago, the problem of transforming positional errors is not devoted adequate attention. Based on determined mathematical models of coordinate transformation within one datum, the paper has suggested some formulae for computing variance-covariance matrices and positional errors in 3 coordinate systems: geocentric, geodetic and plane mapping. These formulae can be easily used in GIS/LIS systems, as well as in land-survey practice.
