At times, you may notice that a vessel appears as Out of Range or that you have not received an updated terrestrial position for a while. This is because the terrestrial-AIS-based MarineTraffic system does not cover 100% of the world's seas, but only specific coastal areas where a land-based AIS receiver is installed. Broaded coverage is available through Satellite-AIS, depending on your subscription.
All vessels that are equipped with an operational AIS transponder and sail within the reception range of an AIS receiving station, installed on the shore, are depicted on the MarineTraffic Live Map. If there is no fresh information on a vessel's recent position, for 24 hours, this vessel is removed from the Live Map until we receive a new position of her.
Common Reasons a Vessel May Not Appear
The vessel is not equipped with an AIS transponder or the transponder is not operational or the transponder is not properly working
The vessel sails in an area where no nearby AIS receiving station exists and Satellite-AIS is not enabled for your account.
The transmission power of the vessel's AIS transponder is not enough in order for a land-based station to receive the signals. This depends on the type of the transponder, the type and the height of the antenna and the quality of the cabling
Especially for vessels equipped with a Class-B AIS transponder, the transmission power of AIS signals is much lower than the power of a Class-A transponder therefore, the reception range is much more restricted. None of our AIS receivers is close enough to receive class B signals, although class A (and some more powerful class B) signals are received and displayed.
The AIS transponder of the vessel is not configured to transmit the correct information (e.g., MMSI number, ship's name, etc.)
If You Have Satellite-AIS and Still Can’t See a Vessel
Even with Satellite-AIS enabled, there are scenarios where vessel positions may not appear:
The vessel is sailing in a high-traffic area (without coverage from our terrestrial receiver network) and the satellite reception is limited due to signal collision or interference.
The vessel is sailing at the Poles, where satellite coverage is limited.
The vessel is equipped with a Class-B receiver, which is more difficult to be picked up by the satellite.