[Case Study] Accident Involving a Traffic Separation Scheme in the North Sea

Credit: Maritime police

A Dutch Safety Board report deals with the Collision in North Sea traffic separation scheme and the lessons learnt from the accident.

Collision between the Amadeus Aquamarijn and the Belgian fishing vessel 

The Dutch Safety Board has issued a report on the collision between the Amadeus Aquamarijn and the Belgian fishing vessel Z60 Blue Angel on 23 December 2021. The collision occurred in the southwesterly lane of the traffic separation scheme above the Wadden Islands. The collision is classified as a serious maritime casualty according to international regulations. The Dutch Safety Board is mandated to investigate this occurrence, based on the Casualty Investigation Code of the International Maritime Organization (IMO). The EU Directive requires a compulsory assessment to determine whether lessons can be learned from the occurrence. Both the Dutch Safety Board and the Belgian Federal Bureau for the Investigation of Maritime Accidents (FEBIMA) conducted an assessment and determined that safety lessons can be learned. The Dutch Safety Board will act as lead investigation state, with the Belgian State acting as substantially interested state.

What happened?

The investigation approach and accountability are discussed in the report, which is available on the Dutch Safety Board website. The report also discusses the role of the watchman on the Z60 Blue Angel and the actions of the second mate on the Amadeus Aquamarijn. The Dutch Safety Board’s investigations do not address issues of blame or liability.

The Dutch Safety Board investigated the collision between the Amadeus Aquamarijn and the Belgian fishing vessel Z60 Blue Angel on 23 December 2021. The Amadeus Aquamarijn was travelling from Hamburg to Antwerp with artificial fertilizer cargo and had engine problems earlier in the voyage. The ship’s captain contacted the shipping company’s technical department, who recommended the vessel leave the traffic separation scheme and seek safe anchorage. The crew attempted to solve the engine problems by replacing a fuel injector, but the problem was not solved. The captain decided to continue his voyage at half power, which was passed on to the technical department. The Netherlands Coastguard was not informed about the engine problems or reduced power, as the situation was under control. The voyage continued normally but at dead slow, at a speed of 4.5 knots. The engine problems were caused by broken inlet valves, and the crew would not have been able to carry out these repairs themselves.

The captain’s watch schedule was adjusted, with the first mate assisting with repairs and the captain taking over watch duty later. The conditions on the water were calm, with little traffic, and no communication with other vessels. During the captain’s watch, the vessel was passed by an overtaking vessel. The captain’s watch was not extraordinary, but the second mate was aware of the situation and switched on autopilot.

The second mate of the Amadeus Aquamarijn, a fishing vessel, was observing the situation around the vessel from 00.00 hours to 05.00 hours. The watch was shared between the second mate and one of the deckhands, who monitored the radar. The vessel was sailing on autopilot at a constant speed of 4.5 knots. At around 03.15 hours, the second mate observed a vessel approaching the Amadeus Aquamarijn from astern, with a CPA alarm triggered on the Electronic Chart Display Information System (ECDIS). The second mate recognized the vessel as the Z60 Blue Angel, which was travelling at a speed of 9.3 knots. The second mate issued a call on the VHF marine radio to warn the fishing vessel, but received no reply.

At 03.34 hours, the Z60 Blue Angel hit the stern of the Amadeus Aquamarijn, causing a second and third collision. The fishing vessel broke free from the Amadeus Aquamarijn. The captain of the Amadeus Aquamarijn was awoken by the impact and called by the second mate. The Z60 Blue Angel was sailing without cargo, resulting in restricted forward visibility from the wheelhouse. The master was present in the wheelhouse for most of the afternoon and evening, checking the route in the chart plotter.

The Z60 Blue Angel, a cruise ship, entered traffic separation system at 10 knots and was observing other traffic. The watch alarm was switched on, and the master could only switch it off. The watchman visited the galley twice, but saw nothing unusual. Over an hour later, the first collision with the Amadeus Aquamarijn occurred. The master was woken by the collision and assumed they had collided with a buoy. Initially, neither the master nor the watchman could observe any object on the radar or out of the wheelhouse window. After altering the course, deck lights on the Amadeus Aquamarijn became visible. The crew reported no call from the Amadeus Aquamarijn prior to the collision.

Following a collision between the Amadeus Aquamarijn and the Z60 Blue Angel, the captain of the Amadeus Aquamarijn contacted the shipping company and the Netherlands Coastguard centre in Den Helder. The captain was instructed to sound the general alarm and activate the pumps, which were activated without realizing a large hole had been punched in the hull. The entire crew of the Amadeus Aquamarijn were on deck in survival suits, and it became clear that the steering engine room had flooded and water was pouring into the accommodation. The engines, generators, and technical systems continued to run normally. After the pumps were switched on, the situation appeared to have been brought under control. Ballast water was pumped out of the ship, and the ship rose higher in the water. The Netherlands Coastguard centre directed the Royal Netherlands Sea Rescue Institution (KNRM) lifeboat and tugboats to the location of the collision, but the KNRM lifeboat was not required to take any action. The Amadeus Aquamarijn sailed into the port of Harlingen, with minimal damage on board. The master of the Z60 Blue Angel was given permission to continue the voyage to IJmuiden at 04.24 hours.

The Amadeus Aquamarijn was sailing on a starboard radar with a NorthUp orientation, increasing its forward looking range. The Z60 Blue Angel had two sea radars, one with a range of 12 nautical miles and an Automatic Identification System (AIS) function, and the other with a range of three nautical miles. Both vessels were sailing using electronic sea charts, with the Amadeus Aquamarijn using a SOLAS certified ECDIS system and the Z60 Blue Angel using an ECS system. The Amadeus Aquamarijn initiated surrounding contacts using an AIS overlay on the ECDIS, while the Z60 Blue Angel used the CPA alarm of the ARPA for surrounding shipping. The CPA alarm was switched off when the vessel was fishing close to other ships due to disruptive sounding.

This investigation aimed to understand the influence of human actions on the accident involving the Amadeus Aquamarijn and the Z60 Blue Angel. A human factor analysis was used to gain insight into why the watchmen on both vessels acted as they did prior to the collision. The analysis used a combination of a timeline, a literature study, the TRIPOD Beta analysis method, and the Recognition Primed Decision (RPD) model, based on Naturalistic Decision Making (NDM).

When did the collision occur?

The collision occurred on Thursday, 23 December 2021, and both vessels were traveling in the same direction. The second mate worked on the bridge computer, triggered the CPA alarm on the ECDIS, and monitored ECDIS. The Z60 Blue Angel collided with the Amadeus Aquamarijn for the first time, hitting the Amadeus Aquamarijn for a second and third time. The Z60 Blue Angel adjusted course to starboard, moving clear of the Amadeus Aquamarijn. The captain and second mate checked the stern part of the Amadeus Aquamarijn, and both vessels were in contact via VHF marine radio.

The captain of the Amadeus Aquamarijn reported the collision to the Netherlands Coastguard. The Amadeus Aquamarijn set course for Harlingen and the Z60 Blue Angel set course for IJmuiden. The investigation aimed to provide the most plausible explanation for the crew members’ actions and lessons learned from their actions.

Various causes for the accident

The Z60 Blue Angel watchman failed to observe the Amadeus Aquamarijn before the collision, resulting in a lack of alertness and work pressure. The watchman was acclimatized to the time zone during the Window of Circadian Low (WOCL), which causes physical drowsiness and lower alertness, negatively impacting work performance. The watchman was on duty from 02.30 hours and was still on duty when the collision occurred at around 03.30 hours.

Work pressure was also a concern, as there was no much other shipping traffic and no route changes were necessary during the watch. This resulted in cognitive underload, leading to poorer performance and passivity. The watchman visited the galley, consulted his mobile phone, and smoked cigarettes on the bridge, potentially reducing attention to monitoring shipping traffic and the shipping route.

Sleep was another factor that could have contributed to the trance-like state experienced by the watchman. Microsleep is a short period of sleep where the person believes they are awake but is unable to respond to external impulses. Sleep inertia, which results in confusion and disorientation but also reduced visual and cognitive capacities, can occur immediately after awakening and last on average for between 1 and 2 hours.


In conclusion, the Z60 Blue Angel watchman’s failure to observe the Amadeus Aquamarijn during the collision highlights the importance of understanding and managing fatigue, work pressure, and sleep during maritime operations.


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Source: Onderzoeksraad


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