1.Introduction
The introduction of AIS-Application Specific Messages (hereinafter, AIS-ASM) is expected to enable mass data transmission with regard to the safer operation of ships (Ahn et al., 2015). The scope of the messages will be quite varied, including navigational warnings, ship-to-ship routine communications, weather information and pilotage (IALA, 2013). In order for users to use this message system in an instant and more convenient manner while navigating ships as responsible officers and managing traffic as VTS operators, it is quite necessary to conduct systematic analysis of the message components and structures and further establish a user-friendly platform for messages (Trenkner and Sevcenko, 2017). Additionally, considering that it is recommended to establish the design of ASM messages in IMO Standard Marine Communication Phrases (IMO, 2010), the research on frequently used phrases seems to be very critical at the moment. In this paper, therefore, with an aim of suggesting AIS-ASM messages on the basis of international guidelines and domestic users’ needs, an extensive survey of marine communication phrase data was first conducted. Following this, the collected data and relevant marine communication phrases were reviewed by specialist panels through a series of workshops and meetings to narrow the target phrases to a manageable number for the questionnaire survey. Next, the questionnaire survey targeting 57 deck officers and 50 VTS operations was conducted in order to encompass the diverse views of different parties. Finally, the data was analysed and suggestions for future AIS-ASM messages were made.
2.Research Methods
2.1.The Overview of the Research Process
A user survey was conducted in order to establish a list of standard phrases according to users' needs. Prior to the survey, the immense volume of marine communication phrases suggested by international guidelines, including IMO SMCP, ITU and International Code of Signals, were collected and condensed enough to make the survey practical (Ahn et al., 2016). The final questionnaire was completed in a total of five stages (Fig. 1) of meetings of and consultations with VHF communication experts.
2.2.Research Process
2.2.1.Data Collection and Phrase Research
The communication database has been established through the collection of the marine communication phrases presented in a variety of international manuals, such as the International Code of Signals (IMO, 2005) and SMCP (IMO, 2002), and reorganising them by category. The total number of the phrases collected is 2,000. This database includes all external communication phrases (e.g., ship-to-ship/ship-to-shore) but excludes internal ones.
2.2.2.Expert Meeting for Classifying the Frequently-Used VHF Communication Phrases
Expert panels, including VTS operators, navigators and linguistic specialists initially attempted the simplification of the data to select phrases out of the whole database that are far less likely to be used in the domestic navigational environment (e.g., related to pirates and polar sea navigation etc.). Through this simplification work, 500 communication phrases were secured.
2.2.3.Workshop on Establishing the Standard Phrases for AIS-ASM Service
A workshop for establishing the standard phrases was held. Four navigators, three VTS supervisors, and two language specialists conducted a meeting to design a questionnaire based on their actual VHF communication experiences. In this meeting, the category of the entire database was redesigned in such a way that users can instinctively find what they want, when they need, either on navigations or VTS, and transmit this information rapidly to other interlocutors. Since it focuses more on user -friendliness, the category is different from the one established in SMCP. The redesigned categories at this stage are as follows: General Communication; Ship-to-Ship Communication; Anchoring Communication; Meteorological and Tide Information; Navigational Safety Information; Distress Communication; Shore Assistance and Pilotage.
In addition, detailed discussions on the 500 updated phrases were made in order to judge their suitability as an AIS-ASM message. Expert panels made the following suggestions: additional phrases for passage between ships are required; navigation safety information regarding special types of ships such as a tugboat or a deep draught vessel should be added; messages indicating the AIS malfunction should be added; transmitting information on pilotage should be detailed; and phrases expressing urgency and emergency during navigation should be excluded.
Last but not least, the language design minimizing ambiguity in words and creating listener-friendly message structures were discussed to ensure that the receiver could immediately understand the selected phrases; this was reflected on the questionnaire. Through the redesign of the phrases, 300 key messages were selected within a total of seven categories.
2.2.4.Phrase Simplification through the review of individual phrases
Based on the 300 phrases reorganized through the workshop, the collection of expert opinions and research were once again conducted to finalize the phrases to be included in the questionnaire. The final appropriateness in the AIS-ASM message design was judged by thoroughly checking each of the selected example sentences. Each of the evaluators rated each appropriate phrase '1' and each inappropriate phrase '0'. The applicable phrase was included only if more than three of the evaluators judged it appropriate. This was done because, considering the characteristics of AIS-ASM messages, there is a physical limitation in transmitting and receiving all the necessary communications in an environment where navigational situations change constantly, and a wide range of message selections may reduce efficiency in operations. Therefore, the design of AIS-ASM messages should be made such in a way that information among 4S can be more easily transmitted by precisely identifying the most repetitive VHF messages patterns between real users.
2.2.5.Establishing Final Questionnaire
The final questionnaire items were established in accordance with the following standards, which are designed to increase unity among phrases and exclude redundancy within them.
Through the standardization process suggested in the table, a total of 109 phrases were included in the final questionnaire within the seven categories: general communication; ship-to-ship communication; anchoring communication; weather and tide information; navigation safety information; distress communication; and shore assistance and pilotage.
The questionnaire was designed using the Likert Scale, allowing respondents to check the following five-point scales: 'Very High', 'High', 'So so', 'Low', 'Very Low', according to the frequency of the phrases.
2.2.6.Participants
The respondents to the questionnaires are as follows:
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. Navigating officers: 57 (with 5.6 years of VHF communication experience)
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. VTSOs: 50 (with 11.64 years of VHF communication experience)
The total number of respondents was 107. Among these, 57 were navigating officers, accounting for 53.27 % of total respondents, and 50 were VTSOs, accounting for 46.72 % of respondents. The average marine communication experience of the navigating officers and VTSOs was 5.6 years and 11.64 years, respectively. The VTSOs have more than twice the years of VHF communication experience on average than that of navigation officers. The VHF communication experience of both groups is 8.65 years on average.
3.Analysis
3.1.The Categories of Questionnaire Items
Prior to beginning the questionnaire analysis, the composition of all questionnaire items were looked into based on the seven categories, which were established after five stages of expert meetings, workshops, and consultations. In this process, the 109 final phrases were confirmed out of an original total of 2,000. In this regard, the questionnaire items themselves are expected to be significantly meaningful when designing the future AIS-ASM marine communication. The number and ratio of the phrases included in a total of seven categories are as shown in the Fig. 2.
As shown in the chart above, the most dominant content of communication phrases in terms of frequency and importance is the 'Navigational Safety Information', which accounts for 26 % of the total phrases. The phrases on 'Distress Communication', 'General Communication', and 'Ship-to-Ship and Routine Communication' account for 18 %, 17 %, and 17 %. 'Routine Communication' and 'Navigational Safety Information', however, which include overtaking one another, altering course, port of call and destination, and navigational warning, were considered more important. Therefore, the ways of being able to search various phrases on the screen in an instant and instinctive manner must be considered so that the messages regarding ship-to-ship or ship-to-shore communication can be exchanged in an immediate fashion.
3.2.Frequently Used VHF Communication Categories
The average frequency of the 109 total items was 3.02. The phrase showing the highest score was 4.72 (e.g., What is your port of destination?), and the lowest was 1.99 (e.g., Do you have any list?).
As shown in the Fig. 3, the most dominant category of all the phrases was 'ship-to-ship communication' with a frequency of 3.75, followed by 'shore assistance and pilotage' (3.71), 'general communication' (3.30), 'weather and tide information' (3.19), 'navigational safety information' (3.16) and 'distress communication' (2.66). In light of the above facts, the message design for routine and safe navigation, such as crossing between ships, communication with VTS centres for berthing and leaving a port must be prioritised. Transmitting and receiving messages for emergency situations does not seem to be suitable for the ones comprising the AIS-ASM messages considering the urgency of situations and the need for immediate responses to and actions in those situations.
3.3.Frequently Used VHF Communication Phrases
Table 1 shows the results of the most frequent VHF communication phrases that scored higher than 3.5 points.
Table 2 shows is the results of the least frequent VHF communication phrases that scored less than 3 points.
As discussed in a previous section, it is quite evident that the general communication for routine navigational situations including 'ship-to-ship communication' and 'shore assistance' are more frequent patterns of marine communications than any others. Of course, in terms of importance (not frequency), the 'distress communication' and 'warnings for safe navigation' have great value. It could, however, be quite challenging for the speakers or listeners (navigating officers and/or VTSOs) to deal with abnormal situations by using a messaging system displayed on screen, rather than evaluating various possible situations in an instant manner by exchanging voice communication with different parties involved to take necessary actions. This has been also pointed out several times in the consultation meetings with experts, who have expressed concerns that the officers or operators could be very disorganised when communicating with multiple stations simultaneously through messengers rather than having one-to-one communication through VHF receivers. In this regard, it might not be appropriate to include the messages for distress situations in the AIS-ASM messaging system.
3.4.Suggestions for AIS-ASM Messages
Based on the research results of the user perceptions discussed above, the major phrases for AIS-ASM messages are designed as follows (Table 3). The total number of phrases is 53 and those scoring a frequency higher than 3 points were included in the final list.
4.Conclusion
With the aim of establishing AIS-ASM messages, users' perception of the frequency of VHF communication was analysed through a questionnaire survey targeting navigating officers and VTS operators.
Based on the analysis, the following should be taken into account in the consideration of the final set of the phrases for AIS-ASM. First, the most repetitive communicative situations should be reflected in the final version of the messages. Considering that most of such situations relate to routine and navigational safety communication, which requires instant communicative actions from recipients, the user interface should be intuitively designed so that the target messages, such as ship-to-ship or ship-to-shore communication, can be more instantly accessible. On the other hand, regardless of their critical importance in maritime communication, the messages for 'distress communication' and 'warnings for safe navigation' were regarded as inappropriate as part of AIS-ASM messages. This is because speakers dealing with abnormal situations are usually required to communicate with multiple parties simultaneously, and various possible situations should be evaluated and considered by the speakers. In this sense, the message exchanges through AIS-ASM should focus more on general routine communication than emergency situations. Finally, in order to make this list more practical and applicable to real communicative situations at sea, the usability needs to be tested, and its practicality should also be thoroughly reviewed for its ability to enhance both safe and efficient communication at sea.