IJCSNS International Journal of Computer Science and Network Security, VOL.8 No.10, October 2008 211 Manuscript received October 5, 2008 Manuscript revised October 20, 2008 Modeling Responsibility Transfer In Man-Machine Systems S. Ahmad † , M. A. Faruqi †† and V. Saxena ††† † Azad Institute of Engineering & Technology, 226002 INDIA ††Azad Institute of Engineering & Technology, 226002 INDIA †††Babasaheb Bhimrao Ambedkar Central University, 226002 INDIA Abstract While there is a continuing trend towards further automation and computerization of complex engineering systems to improve their performance and reliability, there is also an increasing realization that a visible over all human responsibility through monitoring and control of these systems particularly man- machine systems has to continue. This need for the intervention from human beings is acceptable largely due to their better over all situation perception and their crisis handling capabilities. The problems of automation and computerization in the man-machine domains have often been successfully addressed through modularization of the domain, as for example it can be seen in the case of Air Traffic Control (ATC) operations. This approach allows the designers to build an overall human control over each of the modules and it further facilitates in building human interaction and collaboration processes between the modules. Under these conditions the depiction and the visibility of responsibility as it is being shared and transferred between different human beings becomes an important modeling issue. It has been shown through the example of ATC that the above responsibility requirements can be modeled using the extensive massage handling and organizing features of the Unified Modeling Language (UML) Sequence Diagrams. This requires that the development of the diagrams should be carried in such a way that all responsibility sharing actors are included in it. Further, it is shown that through a proposed convention, both full and partial or shared responsibilities can be visually depicted on the diagrams. This approach also paves the way for modeling and depiction of human-computer or human-human interfaces that facilitate mediation between the computers and situation aware human beings. Key words: Air Traffic Control, Domain Driven Design, Human-Computer Interaction, Transfer of Responsibility 1. Introduction Human beings have a unique sense of responsibility, commitment and overall situational awareness, which are difficult to build in the present day computers systems. Thus, they continue to play deciding roles in all safety critical systems specially those involving other human beings. The highly computerized and automated domain of Air Traffic Control (ATC) taken as an example here, is one such field where the overall decision making and control by human beings is an accepted practice. The Air Traffic Control services have evolved and matured over time and today their basic role is to give guidance to aircrafts to prevent collisions and to manage efficient traffic flow. However, to meet the ever increasing safety expectations the aviation systems have been going through a process of continuous improvement and change. These changes coupled with the increasing volume of air traffic, have lead to a significant increase in the work load of Air Traffic Controllers as well as that of the Pilots [1]. Normally, in an ATC system, various operational responsibilities pertaining to take-off, landing and flying of aircrafts are distributed between the pilots and controllers. Some of the responsibilities need to be routinely transferred between the pilots and the controllers while other may have to be done to re-distribute the workload of pilots and controllers as has been brought out in [2, [3], [4]. These new possibilities of responsibility transfers have emerged only recently with the increased capability and availability of relevant communication and control technologies. Responsibilities [5] are essentially either causal which relates to make things happen or consequential which relates to answerability when things happen that should not. While causal responsibilities have same times been assigned to computers, the consequential responsibilities are almost always human and moral. While responsibility has a range of meanings in human-computer environment the moral aspect remains most relevant in the ATC context. Further, the view elaborated in European Commission’s ‘iFly’ project [6] that ‘…a responsible person is defined as to who can take action if required without being required to request permission from another actor’ has been adopted here for modeling. In an effort to evolve the modeling of the responsibility in a man-machine system, roles of mediation and modularization have been brought out [7]. Under these conditions, the capabilities of UML (Unified Modeling Language) [8] Sequence Diagrams have been examined here for modeling some of these functional and non- functional requirements. The presentation has been divided into five sections. Section 2 presents a brief literature review on responsibility modeling and the related issues in human- computer (man-machine) environment. Section 3 deals with the proposition of representing mediation,