The dots crossing the oceans on Aether Track come from AIS — the Automatic Identification System. It's the maritime cousin of aircraft ADS-B: every ship above a certain size is required to broadcast its position, identity, and intent on VHF radio.
Who has to use AIS
- All commercial vessels over 300 gross tonnes on international voyages
- All passenger ships, regardless of size
- Most fishing vessels over 15 m in EU waters
- Many recreational boats voluntarily
What an AIS message contains
Each AIS broadcast carries:
- MMSI — a unique 9-digit ID for the vessel
- Position, course, and speed from onboard GPS
- Vessel name, type, and dimensions
- Destination and ETA, when entered by the crew
The coverage problem
AIS is a VHF signal — it only travels about 40 nautical miles before disappearing over the horizon. Coastal receivers cover busy ports and shipping lanes well, but ships in the open ocean go dark unless picked up by satellite-AIS constellations. That's why a vessel can vanish for hours mid-Pacific and reappear near land.
Reading a track on the map
On Aether Track, click a ship to see its name, flag, type, current speed, and recent track. The arrow shows heading; the trail shows where it's been. Slow speeds plus tight, looping tracks usually mean a fishing vessel working a spot. Long, straight, fast tracks are cargo ships or tankers running between ports.