For over a decade now the Automatic Identification System (AIS) has been considered an important improvement of both the watchkeeping duties at sea and the vessel traffic surveillance activities worldwide. The on-board AIS equipment is used for broadcasting the dynamic data describing the vessel movement vector as well as the static parameters related to her voyage or hull dimension. The reporting intervals of the AIS transmissions depend on the data validity periods which are shorter for continuously changing dynamic AIS parameters and longer in case of less frequently altering static AIS variables. This work focuses on cases of static AIS parameters like the GNSS reference point which were detected to be changing at a high rate, despite the fact that the settings like this are only allowed to be modified during the configuration phase of an AIS transponder. The AIS data received at the DLR reference station in Rostock are analysed and provide a statistical overview of this phenomenon
