Inaccurate VHF & AIS Data Leads To Ship Collision


On August 2018 a container ship and a gas carrier collided. The UK MAIB issued an investigation report on the incident, says an article on the Safety4Sea website.

The incident

At 0636 on 4th August 2018, the UK registered container vessel ANL Wyong and the Italian registered gas carrier King Arthur collided 4 nautical miles south-east of Europa Point, Gibraltar. Both vessels were damaged but there was no pollution or injury.The collision occurred in the darkness during the presence of a dense fog and in an area of heavy shipping traffic.

ANL Wyong was stopped, having been given direction by Algeciras Pilots to wait outside Gibraltar Bay.King Arthur was making way towards a boat transfer position inside Gibraltar Bay.King Arthur’s master was conning, and altered course to starboard intending to pass astern of ANL Wyong.

Although King Arthur’s master could not see ANL Wyong, his assessment of the situation was primarily based on AIS data.

However, ANL Wyong was stopped in the water and not making way as King Arthur’s master had perceived. As a result, the decision to turn King Arthur to starboard actually had the effect of putting the vessels on a collision course.

When King Arthur’s master realised that a dangerous situation was developing, full starboard rudder was applied; however, this action came too late to prevent the collision.

ANL Wyong’s officer of the watch was monitoring the situation, but took no action when it became apparent that a multiple close quarters situation was unfolding.

 Probable causes for the accident 

Neither bridge team acknowledged the risk of collision in sufficient time to take effective action to pass at a safe distance.The investigation also identified that very high frequency radio conversations were a significant distraction on board King Arthur.Additionally, although the collision occurred within a designated vessel traffic service area, neither vessel received a warning of the risk of collision from ashore.

Conclusions from the investigation 

Inaccurate data by the AIS

King Arthur’s master perceived that ANL Wyong was making way in a southwesterly direction when the vessel was actually stopped in the water. This misperception was based on AIS information and resulted in the alteration of course to starboard, intended to pass astern of ANL Wyong, but that actually resulted in a serious risk of collision.Use of AIS data for collision avoidance by both vessels risked misunderstandings and potentially inaccurate data on the relative movements of other vessels.

Lack of communication

The use of VHF radio for collision avoidance was an unhelpful distraction. In particular, the conversation with Spread Eagle wasted time and distracted King Arthur’s chief officer from his primary role of assisting the master with collision avoidance advice.Neither vessel received any warning from the shore agencies responsible for providing information intended to improve onboard navigational decision making


When the shipping situation deteriorated and a serious risk of collision developed, ANL Wyong’s OOW took no action to avoid collision. This was primarily because of his perception that other vessels would keep clear.By taking the con himself in a very busy shipping area, the focus of King Arthur’s master narrowed, reducing his ability to sustain full awareness of the situation.Neither vessel was proceeding at a safe speed for the prevailing circumstances and conditions.Neither vessel took sufficient action to avoid collision and pass at a safe distance.

Actions taken

CMA CGM International Shipping Company Pte. Ltd has:

  • Conducted an internal audit of ANL Wyong.
  • Conducted a company safety investigation that identified the causes and circumstances of the accident.
  • Issued a ‘Lessons Learned’ feet circular to all the vessels in its feet highlighting the issues raised by the accident.

Cautions to be taken 

  • Exercise extreme caution when navigating in restricted visibility.
  • Proceed at a safe speed in restricted visibility.
  • Call the master without hesitation and take action to avoid collision.
  • Always be ready for immediate manoeuvring.

Steps taken by the Mediterranea di Navigazione S.p.A

They conducted an internal audit of King Arthur. This included an onboard education programme by the company staff to review the safety issues identified.They also held an internal safety investigation that identified the causes and circumstances of the accident.They made sure to update the company SMS to include further guidance on safe speed and conduct of navigation in restricted visibility. They further issued a safety article for all vessels highlighting the safety lessons from the accident and provided additional bridge team management training from crew members involved in the accident.


UK MAIB recommended:

-The Spanish Ministry of Development to conduct a review of vessel traffic services in the vicinity of Algeciras designed to enhance the coordination between the authorities involved in order to improve the deconfliction of traffic.

Such a review should consider establishing:

  • A dedicated holding area or anchorage for waiting vessels.
  • A traffic organisation service for vessels in the approaches to Algeciras.

-The Maritime and Coastguard Agency to propose to the IMO that the navigation status information in the AIS be reviewed to ensure that a vessel’s status can be accurately described, including vessels underway but not making way.

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Source: Safety4Sea


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