An unusual pattern of false automatic identification system (AIS) broadcasts concentrated at one location, Point Reyes, off the northern California coast, has drawn the attention of an analyst examining vessel tracking data. The AIS broadcasts showed ships sailing in circles off the coast of San Francisco when they were actually thousands of miles away.

Bjorn Bergman, from SkyTruth and Global Fishing Watch, identified nine locations affected by these types of broadcasting signals and has been trying to figure out why these circling AIS tracks are appearing specifically at Point Reyes. One of the boats, a crew boat traveling to offshore oil installations, broadcasted a normal track out of a Nigerian oil terminal until June 5, 2019. For the following two weeks the vessel broadcasted a false location track circling above Point Reyes and eventually veering off above Utah, during which time the track occasionally jumped back briefly to the Nigerian oil terminal. Other vessels were in Chile, Norway and Malaysia, among others.

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Ship GPS crop circles