COLREGS 72. Use of VHF in Collision Avoidance Last updated 28-Jun-2015

I must repeat, in the hope that it will achieve some publicity, that I have said on previous occasions, that any attempt to use VHF to agree the manner of passing is fraught with the danger of misunderstanding. Marine superintendents would be well-advised to prohibit such use of VHF radio and to instruct their officers to comply with the Collision Regulations.
Per Sheen Judge in The "Maloja II", [1993] 1 Lloyd’s Rep 48

Last updates: Collision between Paula C and Darya Gayatri in Dover Strait

This update can probably be assigned to Mentally lured section (below), although it does not exactly match cases described there. Anyway this case study vividly illustrates how easy one "marker" word can break human line of thoughts, especially when these thoughts are deeply disturbed by difficult task, and unintentionally prompt targeted person to catastrophic action.

Collision between Paula C and Darya Gayatri took place in Dover Strait TSS on 10 of December 2013. OOW on Paula C misapprehend movement of fishing boat engaged in trawling on his stbd side and lost situation awareness. He made several chaotic changes of course to starboard, as he was thinking to pass fishing boat clear, and towards to another vessel Darya Gayatri which was overtaking Paula C from her starboard side. OOW on Paula C did not realized that fishing boat had already changed her course and was no longer dangerous target. But at that moment he was called by Dover Coast Guard officer by VHF and had the following conversation:

Dover CG: What’s your intention now? Are you going to do a three sixty?
Paula C: Errrr, my intention now …. is to, err, do a three sixty, over. Yeah, to starboard.
Dover Coastguard Have you spoken to the vessel that is south-west bound, the Darya Gayatri?
Paula C: No, not yet I’m ehhhh still making my manoeuvre. I haven’t had a chance.
Dover Coastguard: Roger.

After this conversation Dover Coast Guard officer called Darya Gayatri:

Darya Gayatri: Dover Coastguard, Darya Gayatri, I did copy your conversation ah about he will be doing a three sixty ahhh I’ll be coming to port, over.
Dover Coastguard Are you aware of the situation, you can actually see the fishing vessel ahead of you? Is that correct?
Darya Gayatri: Yes, Dover Coastguard, I can see the fishing vessel ahead of me. She altered her course north-west of me now over.
Dover Coastguard Roger. Thank you sir. As long as you are aware. Many thanks
Darya Gayatri: Okay, thank you.

Influenced by conversation with Dover Coast Guard the OOW on Paula C interpreted question about "three sixty" turn as a suggestion, which he immediately adopted as solution to the problem. He put wheel hard to starboard and vessel started quickly approach Darya Gayatri, which in its turn just started her course alteration to port. In few moments vessels collided.

Collision between Paula C and Darya Gayatri

I agree, there was no overuse of VHF in its clear form, but is a good example of incorrect action provoked by VHF communications.


Attending recently Bridge Resource Management courses, I accidentally witnessed a discussion between participants on the subject of the use of VHF in collision avoidance. Several chief officers were advancing their point of view that the sooner they call another vessel to confirm future mutual actions for avoidance of close quarter situation (irrespective whether their vessel is a stand-on vessel or give-way one) the more chances to avoid collision they should have. Understanding of each other intentions, great likelihood to reach mutually acceptable way of actions and verbal confirmation from the opposite vessel of adherence to these actions were declared between the most important benefits of such communications. Among some other advantages were mentioned the following factors:

     • rising attention of another and all nearby situated vessels

     • acknowledgment whether another vessel is aware about development of close quarter situation

     • quick way of obtaining other vessel’s intentions

Although many examples of successful application of these methods were given it was also recognized that in some instances such practice gives an adverse effect or has no positive effect at all, i.e. nobody answers the VHF call. My words that in majority of cases only maneuvering as prescribed by the COLREGS would be sufficient and no any additional calls and agreements would be necessary were met without much sympathy.

As a seagoing master mariner I’m trying to discourage my officers from overuse of VHF in collision avoidance. As a starting point on this way, I offer them to read MGN ‘167 Dangers in the Use of VHF Radio in Collision Avoidance’ (click here if you cannot access this file) a short summary from which states:

Although the use of VHF radio may be justified on occasion in collision avoidance, the provisions of the Collision Regulations should remain uppermost, as misunderstandings can arise even where the language of communication is not a problem.

This document was published by UK MCA in January 2001. Footing on analysis of reported collision cases it underlines several inherent problems of use of VHF in collision avoidance such as:

 •confusion in vessel’s identification

 •distraction from duties

 •language barrier

 •time factor - idle efforts to use VHF instead of proper action complying with COLREGS

From this list only vessel’s identification problem was by now technically resolved to some degree by installation of AIS. Although all remaining difficulties continue to operate, the general attitude of deck officers to use of VHF is, as I infer from personal experience, what the author of MARS 200519 suggests:

…VHF is quite a useful tool that can be used for collision avoidance. Especially when close quarters situations are evolving,…A give-way vessel may at times not be able to take action as per the COLREGS, and it is difficult for a stand-on vessel to determine when it is time for her to take avoiding action and then both vessels end up in a dilemma as to when to start taking action and for how long can one wait until the other takes action. This only leads to a worse situation by delaying the action.

For this exemplary situation author does not offer any particular way of action except calling another vessel on VHF, probably to clarify situation and work out the best scenario of bilateral actions. That way of thinking may appear to be a correct one should we forget that this officer is describing close-quarters situation, perhaps from his own experience, and while understanding that situation is developing from bad to worse ‘by delaying the action’ he sees only one solution to this dilemma: to call another vessel on VHF! In other words he chooses further delay, instead of taking appropriate action as COLREGS and prevailing conditions prescribe.

Identification error

The danger of underestimation of identification difficulties can be illustrated by collision happened in the dense fog between Lykes Voyager and Washington Senator in April 2005(MAIB link). Notwithstanding the fact that both vessels, Washington Senator and Lykes Voyager were equipped with AIS, the passing arrangement agreed by the master of Washington Senator was made with an unidentified ship, and not Lykes Voyager. Master of Washington Senator then altered course to port as he assumed was agreed with the Lykes Voyager. When, finally, master of Washington Senator realised that another ship had turned to starboard and vessels are on collision courses, the distance had reduced to such extent that even last minute avoiding action did not prevent collision. The investigators came to conclusion that:

The developing close-quarters situation between Washington Senator and Lykes Voyager could have been resolved solely by the early application of the COLREGS. However, the master of Washington Senator opted to contact Lykes Voyager on VHF radio.

Proper identification followed by delayed or incorrect action

It is necessary to remember that even when identification is correct and proper actions agreed on VHF, but execution of manoeuvers is bad the result might be just the same negative. That was how the tanker Bergitta collided with the container vessel MSC Eyra in the Great Belt on 24th October 2004. Vessels were navigating in fog but identified each other correctly and well in advance. They further established and maintained VHF contact, apprised each other data (course and speed) and anticipated actions. MSC Eyra as a give-way vessel confirmed that she will pass red-to-red but made starboard turn too late, so late that even the last moment action of deep draft tanker was not enough to avoid collision. Undoubtedly, the fact that another vessel acknowledges and confirms her actions as per passing agreement but actually fails to act as agreed completely devaluates an effectiveness of VHF communication.

Another pilot-involved collision took place between tanker Audacity and cargo vessel Leonis in dense fog on the River Humber on 14 April 2007. Pilots on both vessels were communicating with each other discussing ways to pass clear, without any attempts to increase CPA, just to finally find themselves in situation when collision was collision was probable and imminent.

Identification followed by disagreement about action

Now, let’s have a look at another typical situation. Good visibility, vessels identified each other correctly and officers are discussing passing agreement on VHF. What would then happen if no agreement on further action achieved? On 21st June 2004 Hyundai Dominion and Sky Hope, both container carriers, collided in good visibility due to incorrect assessment of situation by Sky Hope and further disagreement in VHF communications whether it was crossing or overtaking situation. Between several established contributory factors was mentioned this one:

Sky Hope had been observing the approach of Hyundai Dominion. However, other than VHF communication there was no avoidance action taken until she was within a range of 0.2 nautical mile.

In collision between container vessels Hyundai Discovery and ACX Hibiscus in 2013 chief officer of ACX Hibiscus made bold alteration of course to port bringing his vessel on collision course. During subsequent VHF conversation chief officer of Hyundai Discovery was instructing taking over 3rd officer on bridge of ACX Hibiscus not to cross his vessel’s bow and alter course to starboard. 3rd officer of ACX Hibiscus was probably unaware about developing situation but was inclined to follow course alteration commenced by his chief officer. Accident investigation report provides the following assessment of collision avoidance actions between vessels:

Although AIS had provided the chief officer with a positive identification of ACX Hibiscus, as discussed earlier in this report, the VHF radio call did not have the desired effect on ACX Hibiscus’s chief officer. It is acknowledged that VHF radio calls are routinely used by OOWs to advise other vessels of their intentions and to request clarification of another vessel’s movements. However, this method cannot be relied on for collision avoidance, and OOWs must not allow the use of VHF radio to delay them from taking action.

Language barrier

This sentence reflects the main idea of this work – VHF communication is a collision avoidance action – or more accurate ancillary avoidance action. Navigators legally obliged to use all available means which they think necessary to avoid collision. The danger that navigators shall not to underestimate is when collision avoidance begins and ends with VHF communications without proper action at all or when passive communicative part is so prolonged that collision becomes unavoidable.

Another characteristic situation when there is no disagreement between vessels with regard to mutual responsibilities and actions the language barrier problem can still take place. It can be, for example, misunderstanding or misinterpretation of other vessel instructions. Such misunderstanding led to collision between Atlantic and Arngast in August 2005 . Small tanker Arngast was the give-way vessel in accordance with Rule 15 and Atlantic was a vessel "constrained by her draught" in accordance with Rule 3 of the COLREGS. In good visibility two vessels navigated on parallel courses, then Atlantic changed course to port in accordance with her voyage plan. After this maneuver Arngast was closing Atlantic on her port side. Chief officer on watch on the bridge of Arngast established VHF contact with Atlantic 5 min before collision to clarify Atlantic’s intentions. Pilot on Atlantic held the communication with Arngast and informed her chief officer that Atlantic is restricted by her draft and instructed him to alter the course to port as the only way to avoid collision. Chief officer on Arngast took the wheel and put it to starboard. In a minute vessels collided. Investigation identified that the chief officer on Arngast, as OOW, apparently misunderstood the VHF request from Atlantic to turn to port and to slow down, and in stead turned to starboard shortly before the collision.

Mentally lured

The apparent simplicity in reaching passing agreement does not provide any cure against subsequent erroneous actions. The danger, which is hardly recognised by some of my colleagues, who encourage the wider use of VHF in collision avoidance, is over-reliance on information provided by another vessel. There is a crucial difference between anticipation of actions, understanding of intentions and actions as they finally carried out. When agreement has been reached on VHF some officers become mentally lured, i.e. they expect another vessel to execute her maneuvering in accordance with their understanding of developing situation. For example, when another vessel confirms her intention to alter course to starboard, one expects her to do it when he thinks it is proper time and place for her to maneuver and in a way he would have executed this maneuver. Then when something goes not as expected the time is being lost in the first place for realization that agreed pattern as individually understood is not what actually takes place and only afterwards for agonized action.

Collision between tanker Audacity and cargo ship Leonis (also referred above) in part illustrates this thesis, although communicating navigators in that case were pilots on both vessels. MAIB investigation report says:

During the conversation between the pilots, the developing situation was not fully discussed. The pilot of Leonis informed the pilot of Audacity what he was intending to do. Audacity’s pilot, who, having had more opportunity to assess the situation and intending to pass to the north of Leonis, did not question these intentions and deferred to this course of action, offering to reduce speed and come to the south.

Despite not having complete situational awareness of the rapidly developing close quarters situation, the pilot of Leonis was now confident that Audacity would take action to avoid his vessel. He ordered the helmsman to steer 290° to start bringing the vessel towards the inbound TSS. Collision was now imminent,…

Language barrier, wrong assumptions and national incompatibility

In collision between CMA CGM Florida and Chou Shan 19 March 2013, Filipino 2/O was on bridge together with Chinese 2/O who was on board for a period of familiarisation. Filipino 2/O of CMG CGM Florida offered his Chinese colleague to make a passing agreement with Chinese 2/O officer on give way vessel Chou Shan in Mandarin language, which he was not able to understand and therefore was not aware about exact outcome of communication between two Mandarin speaking officers.

MAIB investigation report gives the following analysis:

The Chinese 2/O did not convey fully to the Filipino OOW the content and outcome of his VHF radio communications with Chou Shan’s OOW. Whether or not the two individuals had direct interpersonal conflicts is unclear. However, they were both hampered in their attempts to communicate by having to converse in a second language. Current research suggests that culturally, the Chinese 2/O, although of equivalent rank to that of the Filipino OOW, is likely to have been respectful of the Filipino OOW’s age, experience and authority as the OOW. Research has also identified industry concerns about the compatibility of Chinese and Filipino nationals on board some vessels.

Following each of the two VHF radio communications between CMA CGM Florida and Chou Shan, the Filipino OOW and Chou Shan’s OOW were left with different expectations. A significant contributing factor to this misunderstanding was that the communication was conducted in a language which the Filipino OOW was unable to understand.

CMA CGM Florida’s two 2/Os and Chou Shan’s OOW considered that it was appropriate to use VHF radio for collision avoidance. The latter also considered that it was appropriate to use H for negotiating a manoeuvre that was contrary to Rule 15 of the COLREGS.

The ICS’s Bridge Procedures Guide recommends against using VHF radio for collision avoidance and warns that, even where vessels have identified each other, misunderstandings may still arise. This warning is reflected in the MCA’s MGN 324 (M+F). which further advises that even when VHF radio is resorted to. The COLREGS should be complied with.

The use of VHF radio for collision avoidance was unnecessary, was contrary to internationally recognised best practice, and was a significant contributing factor to the collision.


An obvious idea of this brief analysis is to draw reader’s attention to the fact that establishing of VHF contact and reaching of passing agreement does not bring as such any benefits for the purpose of collision avoidance when COLREGS and rules of good seamanship are forgotten or not followed.In Cargo Lately Laden On Board the M.V.Sun Cross (Owners of) v M.V.Rickmers Genoa (Renamed the Rickmers Dalian) (Owners and/or Demise Charterers of) [2010] EWHC 1949 (Admlty) (30 July 2010), Steel J made it clear that such use of VHF equipment is enhancing the risks rather than limiting them:

… the persistent and unsuccessful attempts to make contact whilst in the meantime making no alteration of course and speed is strongly suggestive of a reliance on VHF contact as the method of first resort in collision avoidance.

Another danger lies in attempts to negotiate passing agreement to bypass the COLREGS. Although such bypassing is not strictly speaking prohibited the use of VHF to propose and agree a course of action for collision avoidance that may not fully comply with the Collision Regulations should normally be for reasons of due navigational prudence and not just convenience. In simple words such use should only be in situations where there is no other alternative.

Believe that many will agree that in any particular situation master or OOW shall realise that irrespective whether one uses VHF to come to passing agreement with another vessel or not, only actions undertaken in compliance with the COLREGS, and not VHF communications, can bring one’s vessel to safety out from collision course. VHF is certainly a helpful tool for the purpose of collision avoidance, but one to be used discreetly, with knowledge of its limitations and only when situation so orders.

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Readers’ comments:

Posted by: Anuj, 1 November 2012

Nicely written article. Explored both sides of the view point on VHF use. Ofcourse the main problem is that there are so many situations at sea that you can hardly generalize.

Posted by: Chris Allport, 21 July 2014

An excellent discussion which comes to the correct conclusion.
".....only actions undertaken in compliance with the COLREGS, and not VHF communications, can bring one’s vessel to safety out from collision course."
This discussion paper contains many of the arguments that explore the issue pointing out the many dangers that VHF introduce into effective collision avoidance.
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