On March 26, 2024, a container ship struck a support pier of the Francis Scott Key Bridge in Baltimore, and within hours a video clip was circulating with a confident caption: the ship had turned toward the pylon. The clip looked damning. The vessel appeared to swing right, directly into the bridge. By that afternoon, a fact-check on Southern Fried Science had already addressed the claim head-on: the apparent sharp turn was an artifact of the camera angle and the sheer scale of the collision, and the public Marine AIS tracks for the MV Dali showed no sharp turn toward the pylon. That is the model. Not a full reconstruction, not a causal finding, not a theory of intent — a specific geometric claim tested against a specific documented artifact, and refuted.
The lesson for a verification desk is narrower and more useful than the viral version: AIS is a citable record with a defined purpose, known limits, and a documented history of being both misread and deliberately faked. Read it as an artifact, not as ground truth, and it will kill bad claims fast. Read it as a truth machine, and you will publish something you cannot defend.
What the artifact actually is
The International Maritime Organization describes AIS transponders as designed “to be capable of providing position, identification and other information about the ship to other ships and to coastal authorities automatically.” That is the purpose statement, and it bounds what a track can prove. AIS exists for identification and collision avoidance, not for forensic reconstruction of intent.
The carriage rules matter for reading any track. The IMO requirement applied to ships of 300 gross tonnage and upwards on international voyages, cargo ships of 500 gross tonnage and upwards not on international voyages, and all passenger ships irrespective of size, effective for all ships by 31 December 2004. The IMO also notes that a flag State may exempt certain ships from carrying AIS. So the first question at the desk is not “what does the track show” but “was this vessel required to transmit, and was it transmitting?”
The technical layer is defined by ITU-R Recommendation M.1371, titled “Technical characteristics for VHF automatic identification system using time division multiple access in the maritime mobile service.” The version in force as of this writing is M.1371-6 (02/2026). The standard defines the message structure — identity fields, position, course, speed, navigational status — and the time-division scheme by which those messages share a VHF channel. When you read a track on an aggregator, you are reading a downstream rendering of messages defined by that recommendation, received by someone else’s antenna, and re-served to you.
The fact-check in action
The Southern Fried Science post did one thing well: it named the specific claim and tested it against the specific artifact. The claim was that the ship steered toward the pylon. The artifact was the Marine AIS track for the MV Dali. The finding was that the track shows no sharp turn toward the pylon, and that the visual impression of a turn is produced by the camera’s perspective and the scale of the event.
That is the strongest editorial use of AIS: refuting a specific geometric or timing claim that a viral clip appears to show. It is fast because the claim is narrow. It is defensible because the artifact is public and the test is stated. It does not require the desk to explain why the collision happened, what the crew did, or what the ship’s machinery was doing. It requires only that the track be read correctly and that the claim be quoted precisely.
What the fact-check did not do — and what no AIS track can do on its own — is establish intent, causation, or a complete reconstruction. The track is a record of broadcast positions and associated fields. It is not a record of decisions, mechanical state, or the full physical environment.
Why “public data” is not “complete data”
The counterexample that should discipline every AIS-based story is the June 2017 collision between the USS Fitzgerald and the container ship ACX Crystal off Japan. Ars Technica reported that the Fitzgerald had its AIS turned off and was not broadcasting its position and course, so there was no current public record of its actions prior to the collision. The same report noted that commanders of US Navy ships frequently turn off AIS to preserve mission security.
Read that carefully. The public track told half the story — the Crystal’s movements — and the other vessel was structurally absent from the record. Any narrative that fills that gap with inference is not AIS reporting. It is speculation wearing the costume of data.
This is not an exotic case. The IMO’s own record shows the organization has been uneasy about public AIS data for two decades. At its seventy-ninth session in December 2004, the Maritime Safety Committee agreed that publication of AIS data transmitted by ships on the web could be detrimental to the safety and security of ships and port facilities, and urged governments to discourage it. That history matters for the desk because it explains why coverage is uneven: the system was not designed as a public transparency tool, and the public record is a byproduct assembled by commercial receivers and aggregators, not an official feed.
The adversarial layer
If the Fitzgerald case shows the record can be incomplete, the warship-spoofing record shows it can be false. WIRED reported that, according to analysis by SkyTruth and Global Fishing Watch, over 100 warships from at least 14 European countries, Russia, and the US appear to have had their locations faked using AIS since August 2020, sometimes for days at a time. The analyst, Bjorn Bergman, concluded the fake messages were likely created in AIS simulator software and copied into the data stream feeding AIS websites, rather than generated by actual malicious transmissions. WIRED also reported that no evidence directly linked the fake tracks to a specific state or actor.
The implication for a verification desk is direct: a track appearing on an aggregator is not proof of a physical vessel at that position. The question to ask is which receivers reported the messages and whether any independent source — satellite imagery, port CCTV, a vessel-traffic-service record, a news photograph — corroborates the position. The marine casualty guidance literature makes the same point from the investigative side: AIS reception quality depends on line-of-sight radio propagation, antenna height and spectrum congestion, and gaps, duplicated reports, incorrect MMSI assignment and multipath anomalies are common. The same guidance advises treating AIS and VTS as complementary — AIS gives identity and voyage intent, while VTS radar and recorded imagery provide independent positional corroboration — and warns against relying solely on AIS for precise position in collision analysis.
A reading protocol for the desk
Apply this in order. It takes minutes and it prevents the most common errors.
1. Name the vessel and its transmit status. State which vessel’s AIS you are reading and whether it was transmitting. If a vessel was not required to carry AIS, or was exempt, or had it switched off, say so before you quote any track. The Fitzgerald case is the standing warning.
2. Quote the specific claim being tested. “The ship turned toward the pylon” is testable. “The ship was reckless” is not. Write the claim in one sentence and keep it in front of you while you read the track.
3. Separate identity and voyage fields from position fields. The MMSI, vessel name, call sign and voyage-related fields identify the transmitter. The position, course, speed and timestamp fields describe where it was. A mismatch in the identity fields — an MMSI that does not match the vessel name, a sudden change in static data — is a flag, not a detail.
4. Cross-check against at least one independent source. Satellite imagery, shore CCTV, VTS records, port authority statements, or a second aggregator with different receiver coverage. A single aggregator screenshot is a citation of that aggregator, not of the physical world.
5. Timestamp in UTC and state the source. Aggregators render times in local zones and sometimes interpolate between reports. Convert to UTC, state the conversion, and name the aggregator and the retrieval time. If the track has gaps, say where they are.
6. Label intent and causation as unestablished unless a separate document supports them. A track can show that a vessel’s position changed. It cannot show why. The National Transportation Safety Board’s investigation docket, a coast guard report, or a court filing can address causation; an aggregator screenshot cannot.
The distinction that keeps you out of trouble
“The track does not show X” is a claim about the dataset. “X did not happen” is a claim about the world. The first is usually supported by an aggregator screenshot. The second usually is not. The MV Dali fact-check stayed on the first side of that line: the track shows no sharp turn toward the pylon. It did not claim to know what the crew intended or what the machinery was doing. That discipline is why it held.
The same discipline applies to the warship spoofing record. “The track shows the vessel approaching the base” is a claim about the data. “The vessel approached the base” is a claim about the world, and in the documented cases the satellite imagery showed empty ocean. The gap between those two sentences is where corrections get written.
What AIS can and cannot do for a newsroom
It can refute a specific geometric or timing claim quickly, when the claim is narrow and the track is public and the vessel was transmitting. It can establish that a vessel was in a general area at a general time, subject to reception limits. It can flag inconsistencies worth investigating — an identity mismatch, a gap in coverage, a position that conflicts with independent imagery.
It cannot establish intent. It cannot establish causation. It cannot reconstruct a full encounter when one vessel was not transmitting. It cannot be treated as ground truth when spoofing is documented and the aggregator is a commercial intermediary. And it cannot substitute for the official investigative record when that record exists or is forthcoming.
The habit to carry out of this piece is simple: when a viral clip makes a geometric claim about a vessel, find the track, quote the claim, test the geometry, and state what the dataset shows — not what you believe happened. That is how a public data artifact kills a bad rumor in hours without becoming a new rumor in the process.
Frequently asked questions
Where does the AIS carriage requirement come from? The IMO’s SOLAS regulation V/19 sets out carriage requirements. The IMO states the requirement applied to ships of 300 gross tonnage and upwards on international voyages, cargo ships of 500 gross tonnage and upwards not on international voyages, and all passenger ships irrespective of size, effective for all ships by 31 December 2004. A flag State may exempt certain ships.
What technical standard defines AIS messages? ITU-R Recommendation M.1371, “Technical characteristics for VHF automatic identification system using time division multiple access in the maritime mobile service.” The version in force as of this writing is M.1371-6 (02/2026).
Can I rely on a single aggregator screenshot as evidence? No. Treat it as a citation of that aggregator’s rendering, not of the physical world. Cross-check against at least one independent source — satellite imagery, VTS records, shore CCTV, port authority statements — and state the retrieval time.
What if one vessel in an incident was not transmitting AIS? Then the public record is structurally incomplete. Say so explicitly. Do not fill the gap with inference and present it as data. The USS Fitzgerald case in 2017 is the standing example.
Has AIS data been faked? Yes. WIRED reported that over 100 warships from at least 14 European countries, Russia, and the US appear to have had their locations faked using AIS since August 2020, per analysis by SkyTruth and Global Fishing Watch. The reported method was simulator-generated messages copied into the data stream feeding AIS websites. No evidence directly linked the fakes to a specific actor.
What open datasets can I use for cross-checking? Global Fishing Watch describes its fishing map as a freely available online platform for visualization and analysis of human activity at sea, allowing users to search for vessels, filter by flag State or time period, identify port visits and view encounters between vessels in near real-time. It also publishes datasets and APIs. Use it as a second source, not as a substitute for independent imagery when position is contested.