WATCHOUT Radar errors led to collision

01 Oct 2016 The Navigator

In this series, we take a look at maritime accident reports and the lessons that can be learned.

What happened?
A cruise ship collided with a container vessel in heavily congested waters. The cruise ship’s radar/ARPA had not been set properly. This led to an overload of information at the exact time when the vessels were approaching each other. In addition, no action was taken by the container ship, which was the stand-on vessel, apart from a VHF call made to the cruise ship five minutes before the collision took place.

The Traffic Separation Scheme in place in the area and the proximity of other vessels made it hard for either ship to take early action, even if they had attempted to do so in time. No passenger or crew injuries were sustained and both vessels made port under their own power.

Why did it happen?
Reports into the collision found that the watch-keeping officer on the cruise ship had become confused by the vast amount of information being relayed at the time of the crash, as well as the manner of its transmission. There was heavy traffic in the area, resulting in a large amount of data being communicated.

The container vessel was overtaking the cruise ship on the port side, while another ship was overtaking to starboard. It is possible that the lights from both overtaking ships were confusing when viewed from the cruise ship’s bridge. The watch-keeping officer’s attention was also distracted by a crew member arriving on an administrative errand and needing to be let in via the bridge door, which was kept locked.

The issues

  • The watch-keeping officer on the cruise ship was left to stand watch alone, despite the area experiencing heavy traffic. More could have been done by the captain to ensure he had adequate support.
  • The watch-keeping officer on the cruise ship relied heavily on radar for his anti-collision checks and carried out few visual inspections. He used the ARPA output from two radars instead of just one, meaning that he didn’t have a single, continuous, reliable plot to follow.
  • He allowed himself to become distracted at the wrong time by a crew member coming onto the bridge.
  • The container vessel made little to no attempt to avoid the collision. A VHF call, five minutes before impact, seems to be the only action of significance reported to have been taken.

What changes have been made?

  • The cruise ship’s company’s watch-keeping officers have been advised to set just one anti-collision plot if they are using multiple radars. Further training in radar use has also been arranged. M
  • ore explicit standing orders will now be drawn up to clarify when sole watch-keeping officers should call for assistance.
  • The layout of the Traffic Separation Scheme will be reviewed to investigate reducing traffic concentration in the area.


If you find our accident reports useful, check out The Nautical Institute’s Mariners’ Alerting and Reporting Scheme (MARS). A fully searchable database of incident reports and lessons, updated every month. Seen a problem yourself? Email the editor at Mariners’ Alerting and Reporting Scheme and help others learn from your experience. All reports are confidential – we will never identify you or your ship.