AEGEAN RADAR · GUIDES

Why some ships are missing

The AIS map shows what has been received, not everything that is at sea.

• Receivers. AIS is picked up by land stations run by volunteers. Behind islands and far from the coast there can be no reception.
• Not every boat transmits. Many small boats have no AIS; some ships switch it off.
• Kept positions. We keep the last position of each ship for up to 24 hours and show its age. An old position is history, not the present.
• Outages. If the connection to the data provider drops, the map keeps the last data and says so in the status line.

An empty area on the map does not mean the sea is empty or safe.