Interim report on the investigation of the collision between the crew transfer vessel Iceni Legend and the unmanned surface vessel X18

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Interim report on the investigation of the collision between the crew transfer vessel Iceni Legend and the unmanned surface vessel X18 in the Greater Gabbard Offshore Wind Farm, 25 nautical miles east of Felixstowe, England on 19 September 2025

The information contained in this interim report is based on the various aspects of the investigation completed to date. Readers are cautioned that there is the possibility new evidence may become available that might alter the circumstances as depicted in this report.

FACTUAL INFORMATION
At 1213 on 19 September 2025, the 22.4m crew transfer vessel Iceni Legend and the 4.58m uncrewed surface vessel X18 collided in the Greater Gabbard Offshore Wind Farm, 25 nautical miles east of Felixstowe, England. At the time, Iceni Legend was heading to a wind turbine to transfer personnel, while X18 was conducting an underwater survey. Iceni Legend sustained damage and water ingress to its port bow and returned to port without assistance. X18 was catastrophically damaged and sankafter the collision. The wreckage of X18 has not been recovered from the seabed.

INVESTIGATION
The MAIB’s investigation has considered all aspects of the accident to determine the causes of the collision. These include the environmental conditions on the day, the ability of both vessels to see and communicate with one another, and the regulatory landscape surrounding maritime autonomous and uncrewed vessels.

ONGOING ACTION
The MAIB investigation is complete, and a draft of the report is being prepared and will be distributed to stakeholders for a 30-day consultation period in due course.

Source: MAIB