Which error type must be corrected through calibration or adjustment of instruments?

Systematic errors are those that consistently occur in the same direction and can often be attributed to shortcomings in the measuring instruments themselves or the methodology applied during measurement. Since these errors can be traced to identifiable causes, they can be accurately characterized and subsequently corrected through calibration or adjustment of the instruments. Calibration ensures that the instruments are providing precise measurements in alignment with known standards, thereby reducing the systematic errors inherent to their operation.

In contrast, random errors are unpredictable and can vary in magnitude and direction; they arise from inevitable fluctuations in measurements and cannot be corrected through calibration. Human errors usually stem from mistakes or misjudgments during the measurement process, making them more a matter of training and practice than calibration of equipment. Procedural errors occur due to inaccuracies in the methods or processes used, which may also require adjustments but are not purely tied to instrument calibration. Thus, the focus on systematic errors as those requiring calibration emphasizes the structured approach needed to ensure measurement accuracy in geodetic engineering.