A crude oil tanker called the Symphony 3 made its way up the west coast of Africa in July of this year. It was being watched, and evidence suggests that the crew knew it. The ship’s self-reported location data changed; instead of a range of daily speed between five and eleven knots, it suddenly started reporting unchanging speeds between four and five knots. Something was up.
Legitimate shippers are required to put radio beacons on their vessels that broadcast their location, a safety measure that also has been used to monitor the pace of international shipments. But those transponders can be turned off or used to report fake locations, a tactic increasingly used by illegal fishers, smugglers, and sanctions evaders.
For years, satellite companies specializing locating radio signals have tracked those beacons, which are part of the Automatic Identification System (AIS). Now, they are…
