Briefing

Going dark: Legal risks of GPS jamming and AIS spoofing – collisions and groundings

In this first instalment of HFW’s series of briefings on the legal risks to shipping from GPS jamming and AIS spoofing, we explain what jamming and spoofing involves, before considering the specific threat to vessels in the context of collisions and groundings.

Vessels rely on global navigation satellite systems (GNSS) for navigation, routing, and situational awareness. There are four major GNSS in operation; China’s Beidou, Russia’s GLONASS, the European Union’s Galileo, and the United States’ Global Positioning Systems (GPS). Essentially, GNSS informs the crew of the vessel’s location. GPS is the most widely used and will be the main focus of this briefing mini-series. The Automatic Identification System (AIS) is a tracking system that is mandatory for all vessels of: 300 gross tonnes and upwards engaged on international voyages; cargo vessels of 500 gross tonnes and upwards not engaged on international voyages; and all passenger ships irrespective of size. In limited circumstances (e.g. Red Sea transits), safety and security may justify AIS being turned off, but otherwise its use is key to safe navigation. AIS broadcasts a vessel’s information, such as position, course, and speed, and relies on receiving an accurate GPS signal. The AIS position of other vessels can be displayed on the radar or Electronic Chart Display and Information System (ECDIS). In recent years, GPS and AIS have suffered from vulnerabilities, namely jamming and spoofing.

What is jamming or spoofing?

Although the terms are commonly used interchangeably, there is a difference between jamming and spoofing. GPS jamming is when a vessel’s GPS receiver is blocked by other signals on the same frequencies. As the GPS receiver can no longer receive GPS signals, the result is there is no ability to position fix. On the other hand, AIS spoofing is where a vessel has its GPS receiver deceived by false GPS signals, which causes the vessel’s location to appear to be somewhere other than where it in fact is. To the crew, it may appear that everything is normal, as the vessel may display a position in the vicinity of where the crew would expect to be, unless the position fix is on land and is therefore obvious to spot. AIS spoofing has advanced in recent years, with false locations ranging from a few nautical miles to thousands of nautical miles away from a vessel’s actual location.

Incidents

Whilst jamming and spoofing can occur anywhere, the hotspots have been the Black Sea, Strait of Hormuz, Red Sea, Gulf of Aden, and the Baltic Sea. One of the first public incidents of AIS spoofing was in 2017 when MT “ATRIA”, anchored in the Black Sea off Novorossiysk, Russia, had its GPS reported location as being 20 nautical miles away at Gelendzhik Airport. In the Baltic Sea, GPS jamming is commonplace, such that in June 2025, 13 EU member states, including Latvia, Lithuania, Estonia, Finland, Denmark, and Germany, wrote to the EU High Representative for Foreign Affairs and Security Policy highlighting the risks to shipping (and aviation) from the widespread jamming of GPS from sources in Russia and Belarus.

In recent months, the principal focus of jamming and spoofing activity has been centred on the Persian Gulf and the Strait of Hormuz, driven by the outbreak of war and the impact of defensive measures on GPS signals. One recent report stated that there were 4 AIS spoofing instances in the 2 weeks prior to the outbreak of hostilities, and incalculable instances since.

However, even before the conflict escalation, the most widely affected area was the Middle East. In the last year, the UK Maritime Trade Operations (UKMTO) has issued multiple updates relating to GPS and AIS interference in the Red Sea, Persian Gulf, and the Strait of Hormuz, attributed to several incidents. On 10 May 2025, one day after UKMTO issued an update, the container vessel “MSC ANTONIA” ran aground near Eliza Shoals in the Red Sea whilst enroute to Jeddah, Saudi Arabia. The vessel’s GPS was reported to have been spoofed by hostile actors which manipulated navigation data, making it appear to the crew that the vessel was further south than she in fact was, including at some point being 80 kilometres inland. Further, on 17 June 2025, the VLCC “FRONT EAGLE” collided with the tanker “ADALYNN” 15 nautical miles off Fujairah, UAE, whilst navigating the Strait of Hormuz, with “FRONT EAGLE” having suffered from AIS spoofing on multiple occasions before the collision (although it did not play a part in the incident itself). Multiple P&I insurers have also reported that their members experienced jamming or spoofing, with one P&I insurer stating that its member’s vessel lost GPS signal and ended up 40 nautical miles away from its proposed route. On 4 October 2025, the Qatari Ministry of Transport ordered all vessels in its waters to halt navigation, citing route disruptions due to “GPS technical failures”. On 6 October 2025, the ban was lifted for commercial vessels but remained in place during evening hours for non-conventional vessels, before being lifted entirely on 9 October 2025. More generally, we are also aware of blue-chip vessels being spoofed to appear as onshore in Iran, resulting in innocent owners gaining “red flag” status on various tracking databases, and having to incur time and expense to evidence they were in fact elsewhere. Further consequences could include parties attempting to avoid payments due in respect of the vessel, e.g. freight on delivery.

Given the variety of disputes which may arise out of jamming and spoofing, this briefing mini-series will cover the four most prevalent areas where issues may arise, namely (i) collisions and grounding; (ii) charterparty disputes; (iii) sanctions; and (iv) insurance.

Collisions and groundings

Jamming or spoofing prevents vessels from being able to accurately determine and broadcast their true locations, or receive accurate locations of other vessels, which significantly increases the risk of admiralty incidents, whether collisions or groundings. It is easy to envisage a scenario in which two vessels navigating a natural choke point in a busy waterway, their crews overly reliant on GPS and AIS, fall victim to jamming or spoofing and consequently collide.

It is first worth noting that vessels should not be navigating solely using GPS (whether displayed on the radar or ECDIS) or avoiding collisions using AIS positions of other vessels. The primary source of a vessel’s navigation should be visual observations and radar, with the AIS specifically being a useful secondary tool. This is confirmed by IMO resolution A.1106(29), which recognises that AIS may be of some use in preventing collisions but that it “is an additional source of navigational information. It does not replace, but supports, navigational systems such as radar target-tracking” and that crucially in respect of collisions, it does not “negate the responsibility of the OOW¹ to comply at all times with the Collision Regulations, particularly Rule 7 when determining whether risk of collisions exists“.

In respect of collision liability, the International Regulations for preventing Collisions at Sea 1972 (COLREGS) apply to all vessels on the high seas and in all waters connected therewith navigable by seagoing vessels. Whilst liability would depend on the exact circumstances, for example, whether one vessel was overtaking or deemed the “crossing vessel”, Rule 7 of the COLREGS states that every vessel must use all available means to determine if the risk of collision exists. Rule 7 also states that assumptions should not be made on the basis of “scanty information“. In terms of means available to a vessel, specific mention is made of radar equipment, including radar plotting, but there is no mention of AIS. As confirmed by Marine Guidance Note 324 (M+F), decisions should therefore be made on systematic visual and/or radar observations. As a consequence, a crew’s reliance on AIS could put a vessel in breach of Rule 7 by relying on “scanty information“.

Therefore, if a vessel were to collide with another, during a period of jamming or spoofing, it could not expect to avoid or lower its liability on the basis of GPS and AIS interference. This is especially relevant since Marine Guidance Note 379 (M+F) specifically describes the risk of over reliance on GPS and AIS that may be compromised by jamming or spoofing. The Admiralty Court would likely question why a vessel was not using radar or a lookout as primary sources of anti-collision measures. In the case of owners and/or demise charterers of “ELEFTHERIA” v owners and/or demise charterers of “HAKKI DEVAL” [2006] EWHC 2809 (Admlty), the Admiralty Court specifically referred to the dangers of relying on AIS as it may be erroneous. In Evergreen Marine (UK) Ltd v Nautical Challenge Ltd. [2021] UKSC 6, where one vessel’s AIS was inoperative, the Supreme Court stated that there was no substitute for visual observations, repeated compass bearings, and the use of radar. Reliance on electronic systems, such as AIS, which may not be operational was said to not be “a complete substitute“.

In a grounding context, similar criticisms of the vessel’s navigation could arise, and would likely be relied upon by contractual counterparties suffering loss, to support allegations of unseaworthiness.

Jamming and spoofing places vessels that are overly reliant on GPS and AIS for navigation at increased risk of admiralty incidents. As the primary source of navigation should be visual observations, repeated compass bearings and radar, owners should take proactive steps to ensure their crews use GPS and AIS systems only as secondary navigational tools.

These issues also have important implications in the charterparty context, which are considered further in the next briefing in this series, “Going dark: legal risks of GPS jamming and AIS spoofing – charterparties”, exploring common areas of contractual dispute.

If you require guidance on any of the issues addressed in this briefing, or would like to discuss HFW’s work in this area, please do not hesitate to contact the authors.

Footnote