AIS-assisted collision prompts call for change

Paul Gunton

Paul Gunton · 20 March 2020


A collision off Gibraltar has led to a recommendation that AIS data should include an additional status field to deal with potential confusion over which way a target ship is moving.

The UK’s Marine Accident Investigation Branch (MAIB) made that recommendation public yesterday (19 March) in its report into the August 2018 collision between the UK-registered container vessel ANL Wyong and the Italian registered gas carrier, King Arthur, south-east of Gibraltar. Both vessels were destined for nearby Algeciras.

ANL Wyong port quarter damage MAIB pic
ANL Wyong was holed above the waterline (image: MAIB; Crown copyright)

Interpretation of the AIS data and over-reliance on it were two important factors, among many, that contributed to the accident making this, in my view, a classic example of an AIS-assisted collision.

Ever since AIS was introduced as a safety measure to identify passing ships, it has become ever-more embedded into navigational decisions, often at the expense of paying attention to ECDIS and ARPA information that could give a better perspective.

If there were ever a situation in which a better perspective was needed, it was this one: it was dark, there was dense fog and heavy shipping traffic. On top of that, although they were within a recognised vessel traffic service area, they were not warned of the developing risk by the shore authority responsible for traffic safety in the area.

You can read the full report via this link but, briefly, ANL Wyong was stopped and waiting for a pilot while King Arthur was heading towards a boat transfer position near Algeciras. “The accident happened because neither vessel appreciated the risk of collision in sufficient time to take effective avoiding action and pass at a safe distance,” MAIB’s summary of the situation explains.

What confused King Arthur’s master was that the AIS information he was looking at said that the ANL Wyong was ‘underway using engine’ and heading in a south-westerly direction. In fact, although the ship was on a heading of 197°, it was stopped in the water, its engine was not running and, because of a north-easterly current, it was moving over the ground at 2.2kts in a direction of 060° – almost the opposite of what King Arthur’s master assumed.

King Arthur bow damage MAIB pic
King Arthur suffered bow damage in the collision (image: MAIB; Crown copyright)

No wonder, then, that when he changed course to avoid ANL Wyong, its closest point of approach (CPA) did not increase as he had expected. In fact, “had the master maintained his heading, ANL Wyong would have passed close to starboard; however, this alteration of course created a serious and immediate risk of collision,” the report concluded.

Meanwhile, the OOW on ANL Wyong tried to contact King Arthur with VHF, something else that MAIB highlights in its report.

Visibility was so poor that it was only moments before the collision that the master and chief officer of King Arthur saw ANL Wyong’s superstructure deck lights. On ANL Wyong, “none of [its] bridge team saw King Arthur, including the deck cadet, who was on the port bridge wing,” the MAIB investigation found.

In an attempt to prevent similar incidents, MAIB’s recommendation is that AIS systems should include an extra ‘status’ option to indicate when a ship is ‘underway’ but not actually making any way and has asked the UK’s Maritime and Coastguard Agency to propose this change to the IMO. It says there are 16 data fields available for status information in an AIS but only 15 of them are currently used, so there is capacity to add the option it has suggested.

But there is a second significant point that emerges from the report, which I believe merits equal attention.

During the incident, both vessels had at least one radar set to prioritise AIS information rather than ARPA data and I presume this is how they generally configured their equipment. And if that is how those two ships operated, I am sure many others do the same.

In its report, MAIB drew attention to The Bridge Procedures Guide, published by the International Chamber of Shipping, which includes this advice: “Due to the risk of confusion and error, VHF radio and AIS should not be relied upon for collision avoidance”. That guide goes on to point out that “there is no provision in the COLREGS for use of AIS information, therefore … the availability and display of AIS data similar to one produced by systematic radar target-tracking (eg ARPA) should not be given priority over the latter.”

Despite this clear warning, on the evidence of this report it is common practice to do exactly the opposite. So while I welcome MAIB’s recommendation, I believe that equipment makers should consider whether it is safe to provide this set-up as an option or, if it is selected, whether they should display an alert to advise that this is not in line with COLREGS.

I used to edit a magazine dedicated to shipping safety and have read many incident reports from across the globe. A significant number of them reveal that practices and policies can develop and become part of normal operating procedures only to reveal a fatal flaw in some exceptional situation.

So whatever the outcome of MAIB’s initiative, I urge all ship operators to bring this report to the attention of their superintendents, crews and managers and to consider whether their own standing orders should be changed in the light of this incident.

• What guidance does your company give its crews about interpreting their AIS? Do you have standing orders about configuring radars? If you manufacture navigational equipment, are changes needed in the settings they offer? Email me now with your views.

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