MariTrace, 4 April 2024
At 17:00 UTC on 3 April, UKMTO issued an unusual incident report: a commercial vessel, identity undisclosed, had experienced disruption to electronic navigation systems (GPS/AIS) over a period of about two hours, starting from approximately 23:00 UTC on 2 April, while transiting the Persian Gulf, 95NM east of Ras Al Zour, Saudi Arabia. Issued amid frequent updates about missile and drone attacks on commercial ships in the Gulf of Aden and Red Sea, the report draws attention to yet another challenge for regional maritime security: electronic interference.
What is electronic interference?
The term ‘electronic interference’ refers to the deliberate alteration of data transmitted by e.g. radio and internet (not to be confused with electromagnetic interference – an emitting source (natural or man-made) that disrupts e.g. radar and electronics equipment). In the maritime sector, the term electronic interference is generally used in reference to the deliberate disruption of navigation and positioning data transmitted through the global navigation satellite system (GNSS). GNSS interference can enable ship diversion and hijacking of cargo, disrupt port activities, distort data used in insurance claims and conceal the manipulation of Automatic Identification System (AIS) data (e.g. to enable the illicit global oil trade). Ship positions can be deliberately altered to obfuscate a ship’s true position, or just get caught up in a wide area of electronic interference, causing their position report to fail and therefore compromising the ability to safely navigate. Interference can generate ships where there are none, cause a ship’s apparent position to jump erratically and disrupt positioning, navigation and timing (PNT) data.
Where is electronic interference occurring?
Multiple instances of GNSS interference affecting the shipping industry have been recorded since 2017, including in the Red Sea, Strait of Hormuz and other critical locations for global shipping. Among the more obvious indicators of electronic interference are ships' AIS positions appearing in locations that are physically impossible: for example, on airport runways and far inland. In 2016-7 MariTrace identified almost 1,000 instances of ship positions appearing at Gelendzhik Airport, identifying a pattern that correlated with airport peak hours. Our independent findings from 2017 were later found to be consistent with published research. GNSS interference is known to have increased after 2020. In October and November 2023, a spike in apparent GPS spoofing was seen to affect aircraft paths across the Black Sea and beyond, with the effects of interference felt far away. The phenomenon is well-known in areas of active conflict (however, there may be several good reasons why GPS has not been completely jammed or destroyed in conflict zones).
In 2023 a missile strike on a cargo ship at the port of Pivdennyi in Ukraine, prompted extensive analysis by MariTrace of the ship’s AIS data, leading to discovery of a large anomaly over a four-month period to 8 November 2023 that affected 211 commercial ships, all reporting positions on the airport runway at Sevastopol, Crimea. MariTrace identified three clusters in the data, suggesting GNSS interference at Constanta (in the western Black Sea) and Sevastopol over four days in early November 2023. One of the ships was found to be fake, transmitting positions at the epicentre of both anomalies. The timing of the anomalies was found to correlate with a known pattern of aircraft GPS interference in the area, during the same period. From November 2023 to March 2024 MariTrace also observed smaller clusters of anomalous ship positions appearing in e.g. the desert in Algeria, at a remote location on the border between Yemen and Saudi Arabia, at Sheremetyevo International Airport (Moscow), at Haifa, Tel Aviv, at Beirut Rafiq Hariri International Airport and at Simferopol Airport (Crimea).
What are the risks to commercial shipping?
Interruptions to GNSS signals and their dependent systems – e.g. AIS and ECDIS - are generally temporary and rarely cause significant impact to shipping. However, given the increased attention to maritime security and freedom of navigation in the areas highlighted by UKMTO, ship operators may be rightly concerned that PNT systems are at risk of being compromised. Electronic interference is among the many operational risks that vessel owners and operators now confront in the Persian Gulf, Red Sea, Gulf of Aden and the Black Sea.
What can ship Masters and operators do to mitigate disruption to their navigation systems?
In 2017, Standard Club offered advice to their members, following a real example of how one ship Master responded to a GPS denial incident in the Black Sea, explaining that the “most effective means to deal with GPS failure is the use of manual fixing combined with [dead reckoning] mode. Every deck officer using ECDIS should be fully aware of how to use the ECDIS equipment in DR mode.” (i.e. navigating using fixed marks, course and speed). In 2022, NATO warned that vessels should expect significant GPS interference in the Black Sea, advising that “If a GPS loss of signal is experienced, vessels must adopt alternative positioning systems or even stop their transit until safe navigation is restored”. On 4 November 2023, shortly before the onset of the current phase of attacks on commercial shipping in the Red Sea and Gulf of Aden, UKMTO issued a notice to shipping warning vessel Masters about electronic interference and requesting that Masters notify UKMTO of any incidents. Similarly, the U.S. Maritime Administration issued an advisory notice in October 2023, identifying significant GPS and AIS interference, globally. The MARAD advisory expired last month. Advice from UKMTO on 4 April simply states that “Masters who experience disruption to electronic navigation systems (GPS/AIS/other PNT) anywhere within the UKMTO Voluntary Reporting Area are requested to notify UKMTO.” It is hoped that increased vigilance may help to identify the full geographic scope of electronic interference and help to correlate incidents with other known GNSS disruptions.
At the time of writing it is not clear if the cause of interference seen in the Persian Gulf this week is similar to the phenomena observed in the Black Sea in November 2023. Given that the effects of electronic interference are often very temporary, it is possible that many incidents in the Persian Gulf and the wider area identified by UKMTO have gone unnoticed (or unreported) since November. That may soon change.
No AI was used in the writing of this article. MariTrace analysis and reporting is based on open sources; all information is human-curated and assessed via multi-phase, structured methods using industry-standard techniques to check for provenance, bias and accuracy.
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