All vessels with a running AIS transponder, which sail within the range of an AIS receiver station, are displayed on the FleetMon Explorer. If there is no current position update for the last 24 hours, the vessel will disappear from the live map until we receive a new position.
Our terrestrial AIS receiver network can only cover specific areas where a shore-based AIS receiver station is installed. The remaining areas are covered underuse of Satellite-AIS.
There are some possible reasons why a vessel is not displayed on the FleetMon Explorer:
The vessel is not carrying an AIS transponder, the transponder is turned off, or the transponder is not working properly.
The AIS transponder does not transmit the correct information; for example, the MMSI number is wrong, so the received AIS signals cannot match the corresponding ship entry in our vessel database.
The transmission power of the AIS transponder is too low for a shore-based AIS station to receive the signals (depending on the type of transponder, type, and height of the antenna) and not in coverage of satellite AIS.
The vessel has a Class B AIS transponder on board and is sailing in a high-traffic area. The transmission power of a Class B transponder is lower than the power of a Class A transponder. As long as the AIS station or satellites receive Class A signals, the reception of Class B signals is restricted.