Use of VHF in Collision Avoidance
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Instead of preface
Treatice of the Law of Merchant Shiips and Seamen, J.H. Lord Tenderden, 1856
Attending 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 avoid close quarter situation (irrespective whether their vessel is a stand-on vessel or give-way one) for confirmation of mutual actions, 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 criticism that in most cases only strict observance with the COLREGS is quite enough and no any additional calls and agreements usually necessary were met without much sympathy.
In my practice 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 after installation of AIS on all ships of 300 GRT and more in international trade. This innovation, however, brings, as I can see, yet another hidden danger: an accurate target identification on AIS tempts navigators to use VHF for collision avoidance to unnecessarily greater extent thus forgetting or underestimating other caveats of the use of VHF (mentioned above) to the detriment of COLREGS.
To find a proof to my words is not a difficult task â€“ watchkeeping on VHF channel 16 gives lots of examples everyday. It makes me wander whether this practice shall soon become an unwritten law, that whenever watch officer on the bridge feels uneasy about intentions of another vessel then his first duty seems to be calling that vessel on VHF. That is exactly what the author of MARS 200519 published in May 2006 issue of Seaways 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 quite innocent or even correct 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’ sees only one solution to this dilemma: to call another vessel on VHF! That what is really amazing… From all the options he chooses further delay in action, which leads by his own words to a worse situation. How much of precious time or sea room might he have, should he finally have succeed in obtaining verbal information from another ship?
Human Factor again
Again, we shall not forget about human factor, which application may diminish usefulness of AIS to the very low level. To illustrate my words I shall refer to collision happened in the dense fog between Lykes Voyager and Washington Senator (if you cannot access file go here) in April 2005. 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.
Now, even when identification was correct and proper actions agreed, but manoeuvring itself was rather late than rather earlier the result might be just the same. That was how tanker Bergitta collided with 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 when the last moment action of deep draft tanker was not enough to avoid collision. At this point shall not any prudent navigator ask himself two simple questions:
1. What do you gain from the knowledge that another vessel confirms her actions as per passing agreement if, in fact, she later fails to act as agreed?
2. Would you have acted with more caution if you had seen another vessel maneuvering dangerously and have had no option to apprise her intention on VHF?
There is 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.
This sentence reflects the main idea of this work – VHF communication is a collision avoidance action â€“ 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.
But even 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.
The idea of this brief analysis of abovementioned collisions is to draw reader’s attention to the fact that establishing of VHF contact does not bring in itself any benefits for the purpose of collision avoidance when COLREGS and rules of good seamanship are forgotten or not followed. The apparent simplicity in reaching passing agreement does not provide any cure against subsequent erroneous actions. The one 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 itself. Moreover, the actions we expect another vessel to undertake, on the basis of verbal VHF agreement, are expected to be in accordance with our understanding of developing situation. For example, if another vessel confirms to alter her course to starboard we expect her to do it when we think it is proper time and place for her to maneuver. Thus applying our own templates for unknown vessels we can find ourselves not ready to cope with those actions of these vessels which do not fit our templates.
Another danger lies in attempts to negotiate passing agreement to the detriment of the COLREGS. This unsafe tendency to substitute compliance with the COLREGS for verbal agreement with another vessel has been duly recognised within maritime society. The Port of London Authority in its NTM No.28 of 2005 stated that:
…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 January 2006 Capt. P.J. Cowing, Harbour Master of Humber River, again drawn attention of masters, deck officers and pilots to MNG 167 and pointed out that:
…the use of VHF to confirm specific agreement on passing manoeuvres,[done] sometimes in contravention of the collision regulations. Such use should only be in situations where there is no other alternative.
Finally, as it was shown in collision between Washington Senator and Lykes Voyager, even vessels equipped with AIS can still find themselves coming to agreement on VHF with unidentified vessels, or as another option AIS information may be misinterpreted or not being used.
I, certainly, have no intention to go same far as Sheen judge in his judgment delivered in collision case The Maloja II, (which was briefly cited in MGN 167) who in his criticism of overuse of VHF in collision avoidance came to the point to suggest that:
Marine superintendents would be well-advised to prohibit such use of VHF radio and to instruct their officers to comply with the Collision Regulations.
First of all such measure is hardly applicable and therefore is of little practical value and, secondly, we must use VHF when necessary at least to the extent prescribed in the Rule 5 of the COLREGS: ‘so as to make a full appraisal of the situation and of the risk of collision’. Albeit too often much wider meaning is being given to the words …full appraisal, when situation can be easily resolved only by proper maneuvering alone in accordance with the COLREGS.
I think in any particular situation master or OOW shall realise that irrespective whether one used VHF to come to passing agreement with another vessel or not, and whatever actions were agreed to avoid collision or were not, the only thing that finally matters is how both vessels have later maneuvered and whether they succeed to pass clear of each other 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. It must be admitted that VHF can be sometimes a helpful tool, one of many available on the navigational bridge nowadays. But as any other tool it should be used discreetly, with knowledge of its limitations, only when really necessary and only to the advantage of prompt and efficient actions as required by the Rules.
Treatice of the Law of Merchant Shiips and Seamen, J.H. Lord Tenderden, 1856
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