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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 6 Conclusions and Recommendations Automatic identification systems (AIS) technology, which has been under development for almost two decades, provides a means of exchanging a precisely defined range of data between ships and between ships and shore facilities under the oversight of competent authorities. It holds the promise of providing accurate and reliable data while reducing the need for radio communications among ships and shore stations, but there are also the possibilities of misuse and unintended negative consequences. Although the implementation of International Convention for the Safety of Life at Sea (SOLAS) carriage requirements has already begun for oceangoing vessels, the requirements do not specify any shipboard display parameters for use by the mariner beyond minimal basic numerical identification data. In this chapter, the committee’s conclusions and recommendations derived from its investigations and analyses of the key issues affecting the design, development, and implementation of shipboard AIS displays are presented. The conclusions and recommendations address the U.S. Coast Guard’s (USCG’s) request for guidance about how to proceed with the AIS regulatory process for AIS displays aboard ships and how to ensure that these displays, when they are developed, will provide sufficient benefits to all mariners and enhance navigational safety and effectiveness in general. They also address the process that USCG will need to follow and the display-related technical and human factors aspects of producing and implementing an effective system aboard vessels. NEED FOR A SYSTEMATIC IMPLEMENTATION PLAN USCG has sponsored and conducted pilot tests of AIS in selected regions and has supported the introduction of AIS technology to enhance vessel traffic management and safety. However, USCG does not have a systematic plan for implementation of AIS in U.S. waterways or AIS displays aboard U.S. vessels. Such a plan is needed because there are important steps in the process that depend on each other to ensure that the vessel operator will derive the ex-
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 pected benefits from an onboard AIS and its display. For example, many of the requirements for shipboard display of AIS information focus on vessels with existing integrated navigation systems, sophisticated hardware, and electronic suites. Requirements for shipboard display of AIS information for small inland and coastal vessels are not well defined and need more analysis. In addition, integration requirements for AIS information with other electronic navigation systems information such as radar, automatic radar plotting aids, electronic charts, and so forth have not been well developed. Additional work in display integration is required to determine how to best integrate existing and new systems. While AIS display requirements in support of vessel maneuvering and collision avoidance are under development, additional work is required before they can be fully adopted. For example, it has been difficult to integrate AIS displays with other bridge displays in a way that presents clear and unambiguous data to the mariner. In addition, AIS display requirements need further development to support the practice of good seamanship in multiple vessel collision avoidance and other emergency conditions. Finally, USCG needs an AIS display implementation process to ensure that the underlying research will be accomplished to demonstrate the viability of the display requirements and that the resulting system will meet the needs of the mariners who use it. Recommendation 1: USCG should establish an implementation plan and schedule for AIS shipboard display standards in consultation with stakeholders. Key elements of the plan should include Research in technical and human factors, Requirements determination and analysis, and Development of international and domestic standards. AIS AND ITS RELATIONSHIP TO SHIPBOARD DISPLAYS In the United States, AIS (as experimental or prototype technology) is in the early stages of implementation and is just beginning to become available within certain port and waterway regions. At the same time, international
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 shipboard carriage requirements for oceangoing vessels under SOLAS have begun to be adopted for the world fleet of merchant vessels. The initial carriage requirements for SOLAS vessels, in the United States and worldwide, will not specify any shipboard display for use by the mariner except for minimal basic numerical identification data. Thus, the implementation schedule for true AIS shipboard displays is uncertain. The introduction of onboard displays of AIS information represents an opportunity for significant improvements in available knowledge and awareness of waterway and vessel traffic situations for all mariners, which should bring safety and efficiency benefits. If AIS displays are introduced carefully and thoughtfully so that the needs of mariners are met without overburdening them with inessential information, the benefits may be considerable. However, the dangers and limitations of this technology could overshadow such benefits, and users and authorities must guard against them. The committee is both encouraged at the prospects for major improvements for vessel operations with the use of AIS and cautious about the problems that could result from less than careful planning. Even though this report addresses only shipboard displays and not the full AIS, the committee understands that the challenge of AIS displays is but one of several facing AIS development in general. For example, while AIS, and displays in particular, complements traditional aids to navigation, it does not replace the need for them. With today’s technology, the prudent mariner should never rely on AIS alone. AIS does not substitute for good judgment or replace the need to use all available means appropriate to the prevailing circumstances to establish vessel position. Not all vessels will carry AIS, which will hinder its effectiveness. Thus, in a typical waterway with mixed traffic, all vessels cannot be located or identified by AIS technology. The unique nature of AIS is that it requires a functioning and reliable transmitter on each target that is part of the system and thus requires each carrier of AIS to participate and cooperate with the protocol. To the extent that AIS provides additional valuable information to the mariner, it will be useful. The current capabilities of AIS provide for the support of three specific functions as defined by a resolution of the International Maritime Organization (IMO): (a) to assist in collision-avoidance while the system is operating in the ship-to-ship mode, (b) to provide information
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 about a ship and its cargo to local authorities who oversee waterborne trade, and (c) to assist authorities engaged in vessel traffic management. As AIS technology and its applications evolve, they will become capable of additional support for vessel navigation and operations. At the current state of development, each of the three broad functions of AIS noted above will affect shipboard display requirements differently. To assist in collision avoidance, an AIS display would be necessary as a direct tool feeding information to the mariner for use while maneuvering in close quarters or planning a meeting and passing situation. With regard to the second function—providing ship and cargo information to local authorities—a shipboard display probably would have little use. With respect to the third function—assisting vessel traffic management—a shipboard display may have a significant role, depending on the nature and design of specific traffic management systems. For example, shore-based data could be transmitted to vessels in a given waterway and then displayed as a means of communicating overall traffic situations and data concerning specific vessels within the area. While the introduction of AIS in both domestic and international settings has been based on these three functions, the initial emphasis has been on the shipboard transponder and the system to ensure accurate identification and location transmissions. Only recently has much attention been given to shipboard display issues. Consequently, much development remains to be done in the form and display of both ship- and shore-originated AIS messages. Although displays can be considered the means by which AIS data are converted into useful information for the operator, little has been done to define the information needs and priorities that would establish display parameters. Different types of information require different display strategies. The design of an AIS display interface needs to consider appropriate strategies for delivering information to the mariner. AIS information will be displayed in many different operating environments: rivers and inland waterways, high-density ports with mixed traffic, coastal waterways, urban harbors with scheduled ferry and passenger vessel operations, and major commercial ports accommodating large deep-sea vessels. In the United States, by far the largest segment of operators who may be required to use AIS are tugs, towing vessels, passenger ferries, and other non-SOLAS vessels.
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 Because of the variety of operating environments, one AIS requirement will not fit all situations, particularly in domestic operations, and implementation plans need to reflect that reality. The operating environment will greatly affect the configuration of displays that are appropriate as well as the operator training that is adopted. And, unlike large oceangoing vessels, many smaller domestic vessels may not carry all of the equipment (such as gyrocompass or satellite navigation) with which an AIS needs to interface for proper operation. The AIS international carriage requirements for oceangoing vessels that came into force during 2002 refer to equipment that is designated as “Class A.” The international bodies have defined two other classes that would be designated for other uses: (a) “Class A derivatives,” which are portable units similar to the carry-aboard equipment now generally used by pilots in several U.S. ports and waterways; and (b) “Class B” units, which have less stringent requirements and are intended for use by domestic, inland, and coastal vessels (e.g., towboats, passenger ferries). The Class A derivative units have received the most attention in the United States because of their similarity to those that pilots have used as carry-aboard units. The definition, role, and display requirements for Class A derivative units are incompletely specified at the present time, and this affects display requirements for such units. Carry-aboard AIS units could be used to fill the gap for vessels that do not have permanently installed AIS equipment. Therefore, there is a near-term need to develop Class A derivative display requirements before full implementation of AIS. Class B units, which are intended for coastal and inland vessels, are also not well defined, and the information display requirements for these units have not been specified. Much more analysis will be necessary on Class A derivatives and Class B before specific display requirements for these units can be established. Recommendation 2: USCG should establish requirements for shipboard display of AIS information in U.S. navigable waters by Defining mariner information needs, Defining key functions for AIS displays aboard different types of vessels and in different operating environments, Developing appropriate requirements for each major vessel class that take into consideration the wide differences in operating environments,
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 Involving the key stakeholders in the entire process, and Developing a new requirement for minimum information display of AIS. USCG should take a leadership role in establishing display requirements for AIS information and work with appropriate international organizations in this process to ensure compatibility with international requirements. DEVELOPMENT OF DOMESTIC AND INTERNATIONAL STANDARDS Display standards are intended to ensure that designs meet user needs, that key requirements are understood, and that a proper certification process can be instituted for all operational units. Standardization of AIS equipment is critical to the safety of navigation and the facilitation of commerce, because shipping is an international business and it is essential that mariners find the same information displayed wherever they sail. International standardization has come late in the development process for AIS. Efforts to standardize technology have been undertaken after many stand-alone systems were already in use throughout the world. This has caused difficulties in producing functional and reliable systems that provide information the mariner can use with ease. In addition, the evaluation of operational tests of AIS equipment has been hindered because no consistent performance standards are available with which to measure results. The process of setting standards and certifying AIS equipment is under way within international bodies for the Class A units specified in current carriage requirements for SOLAS vessels. However, no such standards-setting process has begun for AIS displays either internationally or in the United States. Recommendation 3: USCG should recognize the evolving nature of AIS display technology in its requirements process and allow for technological change, growth, and improvements in the future. HUMAN FACTORS IN THE DISPLAY DESIGN PROCESS For AIS to meet its stated objective of promoting safe vessel navigation, an effective onboard interface with the vessel’s operator is essential. To provide an effective interface, the focus of the design process must be on the best
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 means of exchanging information between the person and the AIS. Although the term “display” is usually used in this report in referring to this interface, it should be noted that, from the perspective of the human operator, the “interface” includes both the display and control mechanisms that allow the exchange of information between the operator and the rest of the system. The interface includes not only the display of information through such means as a cathode ray tube, graphics, and auditory warnings, but also data entry and control elements such as keyboards or switches. Development of an effective human interface for AIS requires a systematic process that considers the capabilities of users and the demands of the operating environment. Three core elements make up a typical design process with human factors as a focus: understanding, design, and evaluation. The process is circular and continues from one element to the next as new factors and inevitable changes are recognized. Within the element of understanding is the notion that advanced technology can increase errors and risk even when appearing to be beneficial. This reinforces the need for attention to the human interface. It is also clear that AIS data must be translated into decision-relevant information for the mariner. Thus it is important to understand how each task of the mariner is performed and how AIS data can support that task and, in turn, overall performance. There are substantial operating differences among the range of vessels that may be equipped with AIS, and it is clear that interface design needs to reflect that range of variation if it is to adequately support operator needs. The second element, design, follows from the first and begins with incorporation of the large body of knowledge about human factors interface guidelines that already exists. Thirteen human factors principles are particularly relevant to AIS interface design. Among them are ensuring that system behavior is completely visible to the operator, avoiding interface management tasks during high-tempo situations, and realizing that the representation of AIS data (e.g., graphic versus numeric) can greatly affect interpretations. Multimodal display alternatives should be considered in addition to graphics and text. Finally, the evaluation element represents the step that tests a design and its performance and leads to either initial adoption or redesign to
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 correct a problem. Heuristic evaluation with multiple evaluators is a very useful approach in identifying design problems. In addition, usability testing and operational evaluation are complementary approaches in identifying problems. Selection of an effective design process will have a large impact on how well a shipboard display and control system provides the promised benefits and avoids unexpected consequences. A combination of design, process, and performance standards is needed to ensure effective designs. Maritime technology and AIS applications will always be difficult to predict. Thus, designers must have the freedom to adapt to changes as they occur or are identified. USCG needs to allow for this in its standards-setting process. Recommendation 4: In its standards, USCG should specify that design, process, and performance standards be used in combination to promote adequate shipboard AIS display design. SYSTEM LIMITATIONS For a shipboard AIS display to function adequately and provide necessary information to the mariner, the overall AIS and supporting infrastructure must also function reliably and accurately. The following are some of the limitations in current systems: The systems are not fail-safe. If the equipment is not operating on board a carrying vessel, it can disappear from the surveillance picture without notice. The systems require the cooperation of the vessels being tracked. A decision not to carry the required equipment or to disable it or otherwise turn it off removes the vessel from the display. The integrity of the data that must be provided by the carrying vessel is not assured. Some data, including data identifying the carrying vessel, are manually entered by an operator and so can be changed or could contain errors. Multiple shipboard sensors (e.g., radar and AIS) can result in multiple displays of single targets. The resulting target ambiguity needs to be resolved through a sorting process, which has not yet been fully developed.
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 The available system capacity for transmitting messages of varying priority and time sensitivity is another factor that may need attention in the overall AIS context because of its effect on shipboard displays. Although AIS has substantial messaging capability, it is not infinite, and the shore-based infrastructure needs to be designed to match traffic volume, message demands, and messaging priorities. Additional message demands due to mariner needs for AIS information could be a key factor in overall system design. Several other infrastructure issues also affect the display of AIS information: transponder coverage and the spacing of shore-based repeater stations, the adequacy and accuracy of digital charting in a given waterway, the availability of existing vessel instrumentation, and the need for standardized interfaces between existing equipment. International standards development efforts have inadequately considered such infrastructure issues and have not considered the impact of infrastructure issues on shipboard display of AIS information. In addition to infrastructure, it is important to consider shipboard operating environments that will shape shipboard display of AIS information, particularly in terms of The range of data that will be transmitted, especially the safety-related elements transmitted by shore stations to ships; The areas or routes used by vessels equipped with AIS displays; The work environment, tasks, and workload of the shipboard bridge watchstanders charged with the safety of navigation; The skill levels of shipboard personnel using the AIS displays and the training and qualifications required to use the displays effectively; The role technology should play, given prevailing and anticipated shipboard workload and skill levels, in converting AIS data into useful and timely information (this factor incorporates consideration of the limits of current “off-the-shelf” display technology); and The benefits derived from mandated displays compared with the cost of fitting and maintaining the displays, taking into consideration training and other associated personnel costs. These and other operating environment factors affect AIS performance in general, and especially the design and implementation of shipboard displays.
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 For example, a potential problem with the use of AIS displays aboard vessels is that the human interfaces can, in some cases, mislead operators into believing that a complex system is well represented by a simple display (sometimes referred to as “the seduction of safety”). Some of this risk can be addressed by good display design. However, the general problem suggests that operator training may be needed in the theory of communication systems, AIS capabilities and limitations, and AIS operations. These and other factors suggest that specific AIS training will be needed and that stakeholders, such as vessel operators, equipment manufacturers, and vessel traffic managers, should be involved in developing training guidelines. Recommendation 5: USCG should identify critical AIS limitations and infrastructure requirements and coordinate them with display requirements. USCG should establish a mechanism to inform all users about system limitations if they cannot be readily corrected. Recommendation 6: USCG should work with stakeholders to develop appropriate training and certification guidelines for AIS users that will lead to effective use and an understanding of system functions and limitations. NEED FOR ONGOING RESEARCH ON HUMAN INTERFACES The development of AIS displays requires a full consideration of human interface attributes that affect what information to display, how to present it to the operator, how to integrate other displays or other bridge information systems, and how to give the operator what is most needed to perform critical tasks. The term “AIS display” connotes a visual presentation of data; however, there are many different methods to provide an effective human interface for information that is vital to the mariner. AIS interface design should be subject to further analysis and critical investigation. For example, the system image and its physical representation will determine its use. A key consideration is whether AIS data will be presented to the operator separately or will be integrated with other existing equipment and information flows. This is a key research area and has received little attention to date. On board certain vessels, AIS units need to fit
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 within existing operational configurations to remain within the mariner’s peripheral vision while not interfering with his or her view of the outside or other equipment. This condition might suggest that different types of AIS interfaces could be adopted, such as wearable computing devices, enhanced binoculars, or a mix of tactile and auditory devices. In addition, AIS interfaces could consider multimodal approaches in order to adequately address competing attention demands. Aboard smaller vessels, AIS visual displays will need to balance the need to be large enough to convey the necessary AIS information and small enough to fit unobtrusively among other equipment. Another consideration aboard small inland vessels is the noise level in the wheelhouse that might interfere with audio interfaces. Another area of necessary research relates to whether and how mariners need to input data into the AIS during the normal conduct of vessel operations and how this might interfere with other duties. Some mariners may have limited opportunities to input data into the system, given competing demands for operational task performance and decision making, particularly on board smaller vessels with one-person wheelhouses. Different types of information may require different data input strategies. Symbology for visual displays is a fertile area for research and development. While some display symbology requirements have been articulated by international bodies, they have not been harmonized across different shipboard electronic navigational displays. This is especially critical for smaller inland and coastal vessels. Furthermore, little work has been done in differentiation of symbols for Class A from Class B and Class A derivatives. The integration of radar and AIS symbols also needs attention and evaluation. Another research area is the cost–benefit trade-off associated with AIS: whether the benefits associated with improved identification and maneuvering/collision avoidance information are worth the cost. For example, do the decision-making and human performance advantages associated with AIS outweigh the human costs in terms of mariner attention management, workload, and vigilance? Studies are also needed to define the information needs for maneuvering and collision avoidance that can be fulfilled by AIS technology. There are several human factors interface research topics that are particular to the operation of smaller inland and coastal vessels, including the eval-
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 uation of competing operator attention demands on board vessels with one operator, high noise levels, multiple communications links, and needs for multiple operational tasks. This leads to the need to consider requirements for specific operating environments rather than universal requirements for all vessels. A challenge for shipboard display design is to find the appropriate balance between the amount of information needed to inform the decision maker in a way appropriate to the decision without overloading the information-handling capabilities of the mariner. The process of determining the proper shipboard display of AIS information will be dynamic and reflect the needs and requirements of differing operating areas. Integration requirements for shipboard display of AIS information raise questions about appropriate task and function allocation between technology and people. For example, designers must strike the right balance between human integration and information processing and automation support for each key task. In addition, shore-based AIS information transmission should be directly linked to the identified mariner needs for that information. There is little commonality in bridge layouts, even for vessels of the same class, and the lack of standardization affects potential shipboard displays of AIS information. Locating shipboard AIS information on a single display can lead to cluttered results, and the value of that information can be degraded by masking or obscuring relevant navigational information. Recommendation 7: USCG should establish an ongoing research program to investigate information displays and controls that might be appropriate for AIS. The research program should consider AIS use with other navigational and communication technologies. The research program should include Human factors aspects of interface design and the subsequent process of determining requirements, setting standards, and evaluating performance; Evaluation of multimodal interfaces (tactile, auditory) that could effectively support mariners’ needs for attention management; Allowance for technological change and leverage of lessons learned from other fields (such as aviation) and related applications of similar technology; and Investigation of trade-offs between information requirements and the associated cost for shipboard display of AIS.
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 NEED FOR CONTINUED OPERATIONAL TESTING OF AIS DISPLAYS USCG and other authorities have conducted a number of operational tests of AIS technology in the United States and abroad. Most of these tests have demonstrated benefits and limitations of the equipment used and shown the operators how it might be used within their operational environments. However, none of the tests with displays has resulted in clear evaluations of performance measured against specific standards. Also, few of the tests on displays have been performed on AIS equipment that was built to IMO standards, and no other standards are available. The committee reviewed several operational tests of shipboard AIS equipment. Most of these tests have not resulted in evaluation reports that clearly and critically document the functioning and usefulness of displays. Anecdotal reports from certain operations using AIS displays (e.g., Sweden and Tampa Bay, Florida) suggest that operators have gained confidence in the systems and used them successfully as navigational aids. From this experience, it appears that the entire maritime community would benefit from more rigorous AIS operational testing with clear functional requirements against which to measure performance, followed by critical evaluations. Recommendation 8: USCG should sponsor continuing operational tests, evaluation, and certification of new display and control technology in consultation with stakeholders and prepare test and evaluation reports. To conduct tests and evaluations, USCG should develop standards for human performance with display and control technology. It should use heuristic evaluation, where multiple designers assess how well a design conforms to human factors rules of thumb or heuristics. It should also incorporate usability tests and operational evaluations as complementary approaches to assess how well AIS displays and controls support mariner performance. SUMMARY The introduction of AIS technology with effective displays aboard vessels operating in U.S. waters can enhance the safety of vessel operations and the prudent management of waterway traffic. The benefits to the maritime community and the nation as a whole will depend on how well the industry,
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Shipboard Automatic Identification System Displays: Meeting the Needs of Mariners - Special Report 273 government authorities, and mariners work together to design effective systems, establish comprehensive standards and guidelines, and implement technologies that provide useful tools for the vessel operator. USCG should take specific actions to ensure an implementation process that meets safety improvement goals. These actions include preparing an implementation plan, establishing requirements for displays and their functions, including human factors in the display design process, addressing system limitations and shortfalls, developing training guidelines, establishing human performance standards, establishing a focused research program, and conducting operational tests and evaluations of display systems. USCG cannot ensure that this new technology will bring the promised benefits to all without the involvement and cooperation of all stakeholders, and without formal evaluation of such systems. Manufacturers, mariners, and the maritime industry as a whole need to be a part of the process to develop effective systems and to successfully implement this technology. While the focus of this report is on shipboard display of AIS information, the process of implementation and the use of human factors principles have wider application to many systems used aboard vessels operating in U.S. waters.
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