The KM3NeT infrastructure comprises two water Cherenkov detectors in the Mediterranean Sea.
Each detector consists of an array of optical modules that are subject to movement due to deep-sea
currents. To ensure an accurate reconstruction of neutrino events, the position and orientation
of each optical module needs to be monitored continuously. This is performed by means of a
dedicated positioning system, composed of acoustic emitters placed on the seabed, and acoustic
receivers integrated into the optical modules. The dynamic positions of the detector elements
are determined via a global fit to the acoustic data. To achieve the envisaged angular resolution
of 0.05 degrees in KM3NeT/ARCA, the position of each optical module must be resolved with
an accuracy better than 20 cm. The orientations of the optical modules are determined using
compass data and need to be resolved with an accuracy of about three degrees. This contribution
presents the global fit method that is currently used for the positioning calibration in both KM3NeT
telescopes, ARCA and ORCA. The movement of the detection units is shown as a function of
time and compared to sea current measurements. Furthermore, the impact of dynamic positioning
calibration on the accuracy of the reconstructed direction is studied for ARCA.