AIS Data in the Strait of Hormuz May Be Missing Half the Picture. Here Is Why That Matters for Logistics.

Key Takeaways

A field investigation by Citrini Research, corroborated by multiple maritime intelligence firms, suggests that AIS data in and around the Strait of Hormuz is underreporting actual vessel traffic by as much as 50%.
Ships are going dark on transponders, spoofing GPS coordinates, broadcasting false destinations, duplicating the identity codes of scrapped ships, and swapping identities with nearby vessels.
Iran is operating what multiple sources describe as a “permission-based” or “tollbooth” transit model. The strait is not fully closed, but passage is selective and politically filtered.
For logistics professionals, the implication is concrete: the vessel tracking data, ETA estimates, port congestion models, and market intelligence reports that rely on AIS are working from a systematically incomplete dataset in this region.
The problem is not unique to Hormuz. It represents an escalation of dark shipping tactics previously seen in Russian sanctions evasion, and it challenges assumptions about how reliable transponder-based visibility actually is under geopolitical stress.

Who This Is For

This post is for freight forwarders, supply chain managers, importers/exporters, and operations teams who use AIS-derived data for vessel tracking, ETA planning, or disruption assessment. If you or your team have been relying on dashboards, market reports, or carrier advisories that reference Hormuz traffic data, this is relevant.

The Citrini Report: Counting Ships the Hard Way

In early April 2026, New York-based research firm Citrini Research published a field report from the Strait of Hormuz. The firm sent an analyst to Oman’s Musandam Peninsula, where he traveled by speedboat into the strait to physically observe vessel traffic.

The central finding: the AIS shipping data that virtually every market participant uses to assess Hormuz conditions is missing roughly half of what is actually transiting on any given day.

According to the report, the analyst observed tankers passing through the strait four to five at a time with transponders completely dark, not showing up on any AIS-based tracking platform. Iran’s ghost fleet was running 29+ laden tankers inside the Gulf with transponders off, moving what the firm estimated at $3 billion in crude to Malaysia since the war started.

The report’s claim has been picked up by CNBC, Seeking Alpha, Seoul Economic Daily, and multiple financial analysis platforms. It aligns with findings from other maritime intelligence providers that had independently identified the same pattern.

Important caveat: Citrini’s findings are based on a single field trip and anecdotal observation. The “50% underreporting” figure cannot be independently verified with precision. But the directional finding, that AIS data in Hormuz is significantly incomplete, is supported by multiple independent sources.

What Other Maritime Intelligence Firms Are Seeing

Citrini is not the only source pointing to AIS degradation. Several specialized maritime intelligence providers have documented the same patterns:

Windward (maritime AI platform) has tracked what it calls “AIS-dark events” across the Gulf region. In its April 6 daily intelligence report, Windward identified 267 AIS-dark events in a single day. The firm has also documented sanctioned tankers employing AIS spoofing, flag hopping, and identity manipulation at Kharg Island.

Pole Star Global reported that roughly one in ten vessels operating in the Gulf are showing “anomalous” AIS behavior, including spoofing, electronic interference, and transponder deactivation. Pole Star’s chief data and analytics officer described vessels as sailing with “forged passports at sea,” noting that some ships are changing AIS destination fields mid-voyage to broadcast messages like “China Owner and All Crew” as political signals to avoid being targeted.

UANI (United Against Nuclear Iran) has tracked at least 26 ghost fleet tankers laden with Iranian oil that have left the Persian Gulf since the conflict started. Some broadcast AIS signals; others operate fully dark. UANI documented tankers briefly switching off AIS while passing Qeshm Island and Larak Island, consistent with Citrini’s observation of a checkpoint-style transit model.

AXS Marine published a detailed multi-segment analysis finding that “AIS disruption, including both signal loss and spoofing, has become a defining characteristic of the operating environment” in Hormuz. Peak AIS signal loss levels in the tanker segment exceeded anything seen in earlier conflict periods.

Scientific American published an in-depth report on GPS spoofing in the strait, citing researchers who described thousands of vessels experiencing navigation interference. The core problem: AIS beacons are fed by compromised GPS receivers, meaning that when GPS is spoofed, the false position propagates to every AIS-based tracking system.

The Five Types of AIS Manipulation Happening Now

Based on the collective reporting, vessels in and around Hormuz are using at least five distinct methods to evade or manipulate AIS tracking:

1. Going dark. Switching off transponders entirely. This is the simplest method and the most common. A vessel that goes dark disappears from all AIS-based platforms until it reactivates. Tankers running dark are invisible to commercial tracking services.

2. GPS spoofing. Transmitting counterfeit satellite navigation signals that cause GPS receivers (and therefore AIS beacons) to report false positions. Ships appear to be circling over dry land, crossing through airports, or drifting through locations they are nowhere near. This makes it impossible to know where the vessel actually is, even if its AIS is technically active.

3. Destination field manipulation. Changing AIS destination fields to broadcast political messages (“China Owner and All Crew,” “India Ship India Crew,” “Iraqi Owners”) instead of actual port destinations. This turns a navigational data field into a signaling mechanism to avoid being targeted by the IRGC.

4. Identity duplication. Broadcasting the IMO or MMSI codes of other vessels, including ships that have been scrapped. Maritime intelligence firm Windward documented cases of “zombie ships” transiting Hormuz using the identity codes of vessels that were demolished years ago. This means AIS systems show a vessel that technically no longer exists making a transit.

5. Identity swapping. Swapping AIS identities with nearby vessels to confuse tracking. This is harder to detect than simple spoofing because both vessels appear to exist and be transmitting, just in each other’s locations.

Why This Matters Beyond Energy Trading

Most coverage of AIS manipulation in Hormuz has focused on oil markets: if AIS underreports traffic, then energy supply models may overstate the disruption, and crude prices may be mispriced. That is a valid financial market concern, but it is not the only implication.

For logistics and supply chain professionals, AIS data integrity matters for several reasons that have nothing to do with oil trading:

Vessel tracking accuracy

If you track container vessels, ro-ro carriers, or general cargo ships that transit or approach the Gulf region, the ETA data you receive may be based on the last reliable AIS position, which could be hours or days old. A vessel that goes dark near Hormuz may not update its position until it reactivates, sometimes far from where tracking platforms estimated it would be.

Port congestion estimates

Congestion models for Gulf ports (Jebel Ali, Khalifa, Dammam, Sohar, Fujairah) rely heavily on AIS-derived vessel counts and anchorage data. If a meaningful share of vessels in the region are operating dark or with spoofed positions, then congestion estimates may understate or misrepresent actual conditions.

Anchorage queue data

The widely reported statistic that hundreds of ships are stranded or anchored near Hormuz is based on AIS data. If 50% of traffic is invisible to AIS, then the actual number of vessels in the region, both moving and waiting, could be significantly different from what dashboards show. This cuts both ways: there may be more vessels transiting than expected, but also more vessels anchored or stranded than visible.

Schedule reliability for connected trades

The Hormuz situation does not stay contained in the Gulf. Vessels delayed in the strait affect schedules in Singapore, Port Klang, Colombo, and onward. Container carriers adjusting rotations or omitting ports in the Gulf create ripple effects across Asia and into Europe. If the underlying AIS data for the Gulf is unreliable, then the downstream schedule predictions that depend on it become unreliable too.

War risk and insurance decisions

Carriers and insurers are making coverage and routing decisions based in part on AIS-derived risk models. If those models undercount traffic (because dark vessels are invisible) or mislocate vessels (because of spoofing), then the risk picture is incomplete.

The “Tollbooth” Model: What Is Actually Happening at Hormuz

The Citrini report and corroborating intelligence suggest that the Strait of Hormuz is not fully closed but is operating under a selective, permission-based transit model managed by the IRGC (Islamic Revolutionary Guard Corps).

Key characteristics of the current model:

Transit requires approval. Vessels must submit detailed information through a broker. Payment can be in cash, cryptocurrency, or through diplomatic channels such as unfreezing Iranian assets.
Political alignment determines access. Countries estimated to have secured some form of transit rights include China, Russia, India, Iraq, Pakistan, Malaysia, Thailand, the Philippines, France, and Japan, a list that is reportedly growing.
No vessels with U.S. or Israeli links have transited. This is a hard exclusion.
A dual-corridor system has emerged. An IRGC-controlled northern route and a newer southern route along Oman’s coast, supported by Iran-Oman diplomatic coordination.
VLCC (supertanker) traffic remains minimal. While smaller tankers and LPG carriers are transiting, very large crude carriers are largely not. This means the volume of oil moving through the strait is still far below normal even if vessel counts are higher than AIS suggests.

The practical takeaway for logistics: the strait is neither fully open nor fully closed. It is operating in a gray zone where passage depends on vessel flag, crew nationality, cargo type, and political relationships. AIS data cannot capture this nuance. A vessel that appears stranded on a dashboard may actually be transiting dark. A vessel that appears to be moving freely may be rerouting to avoid the northern corridor.

Operational Note: AIS has been the backbone of commercial vessel tracking for over a decade. Most supply chain visibility platforms, including those used for ETA prediction, exception management, and carrier performance benchmarking, rely on AIS as a primary data source. When AIS becomes unreliable in a high-traffic, high-stakes region, the gap between what tracking platforms show and what is actually happening widens. This is where multi-source intelligence, combining AIS with satellite imagery, port data, and carrier-confirmed milestones, becomes operationally necessary rather than optional.

What Logistics Teams Should Do With This Information

This is not a situation where there is a neat checklist of actions. But there are several things worth considering:

1. Do not treat AIS-derived Hormuz data as definitive. If your team is making routing, quoting, or customer-communication decisions based on dashboards that show Hormuz traffic data, understand that the data likely undercounts actual activity. This does not mean the situation is less serious than reported. It means the data picture is incomplete in both directions.

2. Cross-reference vessel tracking with carrier-confirmed milestones. For cargo in or near the Gulf, carrier-confirmed events (loading, discharge, gate-out) are more reliable than AIS-derived position estimates. If your visibility platform shows a vessel’s last position as somewhere in the Gulf with no update for 48 hours, that may mean the vessel went dark, not that it stopped moving.

3. Ask your carrier or forwarder about routing specifics. Generic “Middle East disruption” advisories may not tell you whether your specific vessel is on a route that transits Hormuz, calls a Gulf port, or is being rerouted. Get specifics.

4. Factor AIS uncertainty into your dwell time and ETA estimates. If congestion and anchorage models are based on incomplete AIS data, then the dwell time estimates derived from them may be off. Build wider buffers into customer-facing ETAs for cargo touching the Gulf region.

5. Watch for the downstream effects. Even if your cargo does not directly transit Hormuz, the disruption is affecting bunker fuel availability (Singapore supply is running down), vessel schedules across Asia, and carrier network adjustments globally. The fuel surcharge post we published earlier this month is directly connected.

What This Tells Us About Visibility in Contested Environments

The Hormuz AIS situation is an extreme case, but it is not an isolated one. AIS manipulation has been documented in the Black Sea (linked to the Russia-Ukraine conflict), the South China Sea (linked to territorial disputes), and parts of West Africa (linked to illegal fishing and sanctions evasion).

The pattern is consistent: when geopolitical pressure increases in a maritime region, AIS reliability decreases at exactly the moment when accurate data matters most. The systems designed to provide visibility become less trustworthy under the conditions that make visibility most valuable.

For the logistics industry, this is a structural challenge, not a one-time event. It argues for visibility approaches that do not depend on a single data source and that can identify when data quality is degrading rather than simply displaying whatever AIS reports as truth.