Exclusive compilation: Complete record of shipping anomalies in the Strait of Hormuz over 4 days, with increased AIS interruptions and route modifications

Ask AI · How can 4 consecutive days of data reveal the risk internalization process?

From March 11 to 14, shipping around the Strait of Hormuz was clearly hit by regional tensions. Based on monitoring data from multiple parties, including ShipVisionBao, S&P Global, and Kepler, this article provides an exclusive review of the movement of relevant vessels over the past four days.

Judging from the results, the change is no longer just as simple as “there are fewer ships.” More notably, vessels of different ship types, different flags, and different courses have started to show AIS signal interruptions more frequently, to rewrite broadcast content, and to selectively retain signals. In other words, risk has moved beyond tension expectations in the news and has further been transmitted into real commercial shipping operating behavior.

First, look at March 11.

According to ShipVisionBao monitoring, when the bulk carrier “Guan Yuan Fu Xing” was sailing toward the Persian Gulf, its AIS signal was changed to “Chinese shipowners.” When the “Iron Lady” vessel was sailing toward the Strait of Hormuz, the AIS signal temporarily displayed “Chinese-related text.” Meanwhile, another Cosco-affiliated bulk carrier sailing toward the Strait of Hormuz had its AIS broadcast show “Chinese operator/shipowner.”

On the same day, according to S&P Global monitoring, ships such as the very large liquefied gas carrier “Mather,” the medium-sized tanker “Breeze,” and the very large crude oil tanker “Star Glenning Sween” continued to broadcast normally on AIS.

However, according to Kepler monitoring, among crude oil tankers, liquefied petroleum gas carriers, and bulk carriers, there were already cases of AIS signal interruptions.

This means that what appeared on March 11 was not a single trend. Instead, within the same day, two states had already diverged: some vessels maintained normal broadcasting, while others began to reduce exposure risk through signal interruptions or even by rewriting broadcast content.

Now look at March 12.

According to ShipVisionBao monitoring, on that day the AIS signals of crude oil tankers, liquefied natural gas carriers, and bulk carriers overall returned to normal broadcasting.
According to S&P Global monitoring, crude oil tankers, liquefied petroleum gas carriers, and bulk carriers also largely maintained normal broadcasting on that day.
But according to Kepler monitoring, crude oil tankers and liquefied natural gas carriers still had AIS signal interruption occurrences.

This shows that March 12 cannot be simply understood as risk disappearing. It is more like a divergence in how ships respond to risk under different platforms and different sample ranges. Some ships resumed normal broadcasting, while others continued to stay cautious. This kind of split itself reflects that the situation is unstable.

By March 13, abnormal characteristics began to concentrate even more in the tanker direction.

According to ShipVisionBao monitoring, both the ultra-large crude oil tankers “Tianbo” and “Kum” showed AIS signal interruptions when sailing toward the China/India direction; at the same time, one liquefied petroleum gas carrier and one bulk carrier maintained normal broadcasting.

According to S&P Global monitoring, ultra-large crude oil tankers also showed AIS signal interruptions when sailing toward the China/India direction; liquefied petroleum gas carriers showed similar occurrences as well.

According to Kepler monitoring, not only did ultra-large crude oil tankers have AIS signal interruptions, but even Suezmax tankers showed AIS signal interruptions when sailing toward the China/India direction.

This indicates that by March 13, risk was no longer only concentrated in ships entering the Persian Gulf or nearing the Strait of Hormuz. Even tankers sailing toward Asia—especially those connected more tightly to routes related to China and India—began to show clear precautionary actions. Tankers became one of the most sensitive ship types, reflecting that market concerns about energy transportation safety had further increased.

Now look at March 14.

According to ShipVisionBao monitoring, AIS signals of ultra-large crude oil tankers and liquefied petroleum gas carriers were interrupted, while bulk carriers and product tankers maintained normal broadcasting.
According to S&P Global monitoring, AIS signal interruptions continued in ultra-large crude oil tankers and liquefied petroleum gas carriers, while bulk carriers were normal.
According to Kepler monitoring, in addition to Marhsall-registered vessels, there also appeared an Iranian-registered ultra-large crude oil tanker with AIS signal interruptions when sailing toward Asia; meanwhile, the liquefied petroleum gas carrier also remained in an interrupted state, while the bulk carrier and another crude oil tanker maintained normal broadcasting.

Putting together the continuous four-day data from March 11 to 14, several features are already very clear.

First, the traffic activity in the Strait of Hormuz and surrounding waters has indeed declined. Whether measured by the activity level of the ship samples or by the density at which abnormal signals appeared, the tense situation has affected normal shipping order.

Second, abnormalities are not distributed evenly; they are highly concentrated in ship types related to energy transportation. Crude oil tankers, ultra-large crude oil tankers, liquefied natural gas carriers, and liquefied petroleum gas carriers are the high-frequency core of this round of AIS interruptions and abnormal broadcasting. By contrast, bulk carriers and some product tankers more often keep normal broadcasting.

Third, the distribution of flags is wide. From Panama, Liberia, and the Marshall Islands to Comoros, Guyana, and even Iranian-registered vessels, they appear in this set of data to varying degrees. This shows that it is not an isolated reaction from a single shipping company or a single national fleet, but a common response by international commercial fleets after regional risk spillover.

Fourth, AIS handling methods have extended from “closing or interrupting” to “modifying broadcast content.” In particular, the broadcast changes such as “Chinese shipowners,” “Chinese-related text,” and “Chinese operation/shipowner” that appeared on March 11 are especially worth noting. This indicates that some vessels are no longer only taking technical evasive measures; they are proactively adjusting external identification information to reduce the probability of being misidentified, targeted, or associated lock-on during high-risk segments.

If you look only at a single day, these changes look more like scattered anomalies. But when you put together the continuous four-day data from March 11 to 14, the trend becomes very clear.

What is truly worth paying attention to is not just that there are fewer ships, but how ships are changing: vessels of different ship types, different flags, and different courses are beginning to show AIS interruptions, broadcast rewrites, and differences in signal retention more frequently.

The significance of this dataset is not simply to repeat the already market-accepted judgment that war will affect shipping. Its more important value lies in making this impact concrete.
From March 11 to 14, the risk in the Strait of Hormuz is no longer just a tense situation found in the news, but has become shipping-behavior changes that can be continuously observed and cross-checked.

For the outside world, the biggest significance of these four consecutive days of data is that it strings together scattered anomalies located across different monitoring platforms, different ship types, different flags, and different courses into a complete track of risk evolution.
And this track shows that the risk in the Strait of Hormuz is evolving from repeated sudden incidents into a more persistent variable for shipping safety.

In terms of the public discourse, the market has long known that the war will disrupt shipping; but based on this dataset, what is truly worth being wary of is that the response methods of shipping companies and the vessels themselves are changing. AIS interruptions are increasing, broadcast rewrites are appearing, energy ships are becoming more sensitive, and tankers heading toward Asia are also starting to show abnormalities more frequently.
This indicates that risk perception has moved from external judgment to further internalization into shipping behavior itself.

And once this kind of change continues, what the Strait of Hormuz faces will not be only local periods of tension, but potentially a more long-term, high-sensitivity operating condition. For the global energy transportation supply chain, this is the signal that is even more worth watching.