=Paper= {{Paper |id=Vol-3107/paper6 |storemode=property |title=Requirements engineering for sociotechnical systems: Case study of an Airline Operations Control Center |pdfUrl=https://ceur-ws.org/Vol-3107/paper6.pdf |volume=Vol-3107 |authors=Nico Zimmer,Kuldar Taveter |dblpUrl=https://dblp.org/rec/conf/apsec/ZimmerT21 }} ==Requirements engineering for sociotechnical systems: Case study of an Airline Operations Control Center== https://ceur-ws.org/Vol-3107/paper6.pdf
          Requirements engineering for sociotechnical
          systems: Case study of an Airline Operations
                        Control Center

                           Nico Zimmer                                                                    Kuldar Taveter
                    The Boeing Company Inc.                                                       Institute of Computer Science
                     Neu-Isenburg, Germany                                                              University of Tartu
                    nico.zimmer@boeing.com                                                                 Tartu, Estonia
                                                                                                       kuldar.taveter@ut.ee

    Abstract—This paper is concerned with requirements                       from the AOCC stakeholders by following the elicitation
engineering for sociotechnical systems. The paper describes and              approach described in [6] and [11].
analyzes the requirements for the sociotechnical system of the
Airline Operations Control Center (AOCC). This is done for                        The rest of this paper is structured as follows. In Section
studying the social part of the AOCC by means of agent-based                 II, the holistic requirements engineering framework for STS
simulation of AOCC employees with different personality                      used in the work is described. In Section III, the framework is
profiles. The requirements are mapped to the viewpoint                       applied to modelling the behavior, organization, and
framework for holistic requirements elicitation and                          information perspectives of the AOCC. In Section IV, the
representation at different abstraction layers and from                      design of the simulation system for the human subsystem of
complementary perspectives. The design of an agent-based                     the AOCC is briefly described, based on the requirements.
simulation system based on the requirements is briefly                       The conclusions are drawn and directions for future work are
described. Finally, the benefits of this kind of requirements                set in Section V.
engineering approach are brought out and the directions for
future work are set.                                                                   II. REQUIREMENTS ENGINEERING FOR STS

   Keywords—sociotechnical system, requirements engineering,
                                                                                 STS should be designed in a holistic fashion [11]. Holistic
model, abstraction layer, perspective, viewpoint, agent-based                design means, among other things, that the software system to
simulation                                                                   be designed should be viewed through complementary lenses
                                                                             of its social, informational, and behavioral context. For this
                        I. INTRODUCTION                                      purpose, we propose to apply a methodology that is centered
                                                                             on the viewpoint framework defined in [13]. The viewpoint
    This paper is concerned with studying complex
                                                                             framework consists of a matrix with three rows representing
sociotechnical systems. A sociotechnical system consists of
                                                                             the abstraction layers of problem domain analysis, design, and
tasks, people, organization, and technology [1]. In other
                                                                             implementation and three columns representing the
words, sociotechnical systems comprise humans, social,
                                                                             perspectives of organization, information, and behavior. Each
organizational, and technical factors [2]. Sociotechnical
                                                                             cell in this matrix represents a specific viewpoint, such as
system (STS) is defined as a software intensive system that
                                                                             organization analysis, information design and behavior
has defined operational processes followed by human
                                                                             implementation. The perspectives of organization,
operators and which operates within an organization and
                                                                             information and behavior are respectively geared towards
comprises both social and technical aspects [3]. STS consists
                                                                             eliciting and representing social, informational, and
of humans, software, and hardware [3].
                                                                             behavioral contexts. In this paper, we address the viewpoint
    The aviation domain contains many good examples of                       aspects of the system analysis layer because the focus of this
sociotechnical systems. First, modern aircraft should be                     paper is on requirements engineering for STS. Each of these
viewed as STS [4]. In our previous work [5-6], we have                       perspectives – information, interaction, and behavior – can be
studied airports as STS. This paper studies an Airline                       represented by appropriate models. The models at the
Operations Control Center (AOCC) as STS.                                     abstraction layer of system analysis represent the
                                                                             requirements elicited for the STS. Likewise, the models at the
    The research literature indicates that the agent-oriented                abstraction layers of design and implementation respectively
paradigm is a natural metaphor for studying complex STS                      represent the design and implementation of the STS. Since this
because it enables to elicit and represent requirements for both             paper is concerned with requirements engineering, we focus
the social and technical aspects [6-9]. The purpose of this                  on the models required for capturing the highest abstraction
paper is to describe and analyze the requirements elicited for               layer of problem domain analysis and only marginally treat
designing and implementing an agent-based simulation                         the models needed for addressing the abstraction layers of
system [10] for the important social part of the AOCC STS –                  design and implementation.
AOCC employees responsible for dispatching flights. As we
have shown in [6], for successful agent-based simulation of                      The viewpoint framework has been previously applied for
some aspect of STS, the requirements for the greater STS                     requirements engineering as described in, e.g., [6, 9, 14-17].
should be elicited and modelled. Considering this, this paper                The methodology for filling in the viewpoint framework,
describes the requirements elicited for the whole STS of                     including the order of filling, is described in [6]. The
AOCC. The requirements described in the paper were elicited                  advantages of using the methodology based on the viewpoint
                                                                             framework are that it enables to model requirements for STS



Copyright © 2022 by the author. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
at three abstraction layers and from three complementary                                                               III. REQUIREMENTS FOR THE AOCC
vertical perspectives. Another advantage is that the models
included by the viewpoint framework are rooted in simple                                            A. Goal Models and Motivational Scenarios
principles, which makes the models palatable for non-                                                   Goal models are relevant for capturing the purpose and
technical stakeholders. The viewpoint framework is                                                  goals of the STS. Goal models belong to the viewpoint aspect
represented in Table I. This paper is focused on the models of                                      of behavior analysis. According to Sterling and Taveter [12],
organization, information, and behavior analysis.                                                   goal models include functional goals denoted by rhomboids
Requirements models of AOCC of the mentioned viewpoint                                              that represent functional requirements of the system, quality
aspects are presented and explained in Section III. Design                                          goals (clouds) that model non-functional requirements of the
considerations of the agent-based simulation system at the                                          system, and roles (stick figures) that describe capacities or
system design layer are presented in Section IV. Finally, the                                       positions of the system required to achieve the goals. There
simulation system is implemented at the layer of system                                             can also be relationships between functional goals (solid
implementation, which falls outside the scope of this paper.                                        lines), and between goals and quality goals (dashed lines). For
                                                                                                    easier reading, we indicate in this paper goals and quality
Table I. The viewpoint framework
                                                                                                    goals as highlighted in the italic font, and roles in the bold
                                               Viewpoint aspect                                     font.
 Abstraction            Organization            Information     Behavior                                The overall goal or purpose of airline operations control
 layer
 System                 Role models,      Domain model      Goal model,                             is to Maintain & control the day of operation network
 analysis               organization                        Motivational                            schedule to provide an Efficient, safe, quality & profitable
                        model                               scenario                                network operation to the airline’s customers – mainly its
 System design                 Models of platform-independent design                                passengers, but potentially also to its cargo customers. The
 System                           Platform-specific implementation                                  goal model of airline operations control is shown in Figure 1.
 implementation



                                                                                     Operations Control


                                     Efficient, safe, quality &       Maintain & control
                                   profitable network operation        day of operation
                                                                      network schedule


                                         On-time and with
                                              minimal                     Execute
                                            disruptions               network schedule


                      Ground                       Maintenance                                Flight                                     Passenger                 Crew
                      Control                        Control                                 Dispatch                                     Control                 Control




                   Manage                       Manage                 Manage                         Manage                      Manage                       Manage
                                                                                                                                 passenger &
               ground operations         maintenance operations   flight operations                  disruptions                   revenue                      crew


            Turnaround efficient
                and on-time
                                            Aircraft legal and
                                               servicable
                                                                   Flight cost-effective,
                                                                    legal and on-time        Quality service, cost-effective &
                                                                                            minimal impact on network schedule
                                                                                                                                 Customer satisfied &
                                                                                                                                 revenue maximized      Crew legal, sound and
                                                                                                                                                              efficient


Figure 1. The goal model of airline operations control

Table II. The motivational scenario of airline operations control                                                        done in through collaboration between the AOCC sub-
                                                                                                                         roles. The following activities are included:
 Scenario         Airline Operations Control                                                                                  a) managing ground operations by preparing the
 name                                                                                                                              aircraft on the ground and conducting weight and
                                                                                                                                   balance calculations
 Scenario         The purpose of the airline operations control is to maintain
 description      and control the day of operation network schedule. This is
                       b)    managing maintenance operations by reviewing                   their own quality goals to ensure the entire network operation
                             aircraft status, and tracking and solving                      flow. All of these quality goals contribute to the achievement
                             maintenance issues
                                                                                            of the quality goal On time and with minimal disruptions. A
                       c)    managing flight operation by preparing,
                             dispatching, and following flights                             more narrative-like way of representing the meaning of a goal
                       d)    managing passenger and revenue by tracking, re-
                                                                                            model is motivational scenario [13]. Motivational scenarios
                             booking, and accommodating passengers                          belong to the viewpoint aspect of behavior analysis. Table II
                       e)    managing crew by monitoring, tracking, and                     presents the motivational scenario of airline operations control
                             recovering crew members                                        and how agents fulfill their corresponding roles to achieve
                       f)    managing disruptions by gaining situational                    their goals. Additional goal models and motivational scenarios
                             awareness and optimizing and executing proper                  for a day of operation are available in [18].
                             solutions
                                                                                            Since the operational flow is regularly disturbed by
 Quality        Executing and controlling the day of operation network
 description    schedule should ensure an efficient, safe, and high-quality
                                                                                            disruptions which lead to irregular operation, a very important
                service to airline customers – the passengers. The airline’s                sub-goal shown in Figure 1 is Manage disruptions.
                day of operation should be at the same time profitable,                     Disruptions should be managed while they occur, but still
                solvable, and punctual without large disruptions or delays                  ensuring a Quality service, cost effective, and minimal impact
                to maintain the airline’s reputation.
                                                                                            on flight schedule. The responsibility and final decisions of
    Figure 1 reflects that achieving the overall goal of airline                            disruption management lie with the duty manager performing
operations control is the responsibility of the duty manager                                the role of Operations Control, but collaborative decision
performing the role Operations Control. To offer a service to                               making is performed amongst all the sub-roles of the AOCC
airline customers, Operations Control is also responsible for                               represented in Figure 2 to find an optimal solution. Figure 2
                                                                                            also shows the sub-goals of Manage disruptions. Different
achieving the goal Execute network schedule with the quality
                                                                                            aspects of managing disruptions are represented by the sub-
goal to deliver the service On time and with minimal
                                                                                            goals Gain situational awareness, Optimize solution, and
disruptions. The responsibilities for achieving the sub-goals
                                                                                            Execute solution with their respective lower-level sub-goals.
Manage ground operations, Manage maintenance operations,
                                                                                            Table III shows the motivational scenario of disruption
Manage flight operations, Manage passenger & revenue, and
                                                                                            management.
Manage crew are delegated to the respective roles Ground
Control, Maintenance Control, Flight Dispatch, Passenger
Control and Crew Control. Performers of these roles follow
                                                         Flight                                    Operations
                                                        Dispatch       Quality service, cost-       Control
                                               Crew                    effective and minimal
                                                                                                              Passenger
                                              Control                     impact on flight                     Control
                                                                              schedule
                            Maintenance                                                                                   Ground
                              Control                                                                                     Control

                                                                               Manage
                                                                              disruptions




                                    Gain                 Easy to
 Easy and fast to                                                              Optimize                                                   Easy to
                                situational             compare                                               Execute solution
   see impact                                                                  solution                                                disseminate
                                awareness



                                                                   Develop            Evaluate         Communicate          Apply
                    Identify issue   Gather impact
                                                                   solution           solution           decision          decision




                                      Minimize (indirect) cost             Minimize impact on
                                     associated with disruption           passenger convenience


Figure 2. The goal model for managing disruptions

Table III. The motivational scenario of disruption management                                Scenario      Disruptions need to be handled proactively to avoid delays
                                                                                             description   and additional costs. Managing disruptions potentially
 Scenario       Disruption Management                                                                      involves all sub-roles of the AOCC. The responsibility and
 name                                                                                                      final decisions lie with the duty manager performing the
               role of Operations Control. Disruption management                 personality features Conscientiousness (C) and Agreeableness
               includes the following activities:                                (A) have been identified as valid occupational performance
                    a) gaining situation awareness by identifying and            predictors [18]. C and A may have positive or negative
                          understanding the issue and its impact on the
                          disruption, e.g., does it affect my fleet, crew,       influence (indicated by the ‘+’ or ‘-’ sign) on the collaborative
                          and/or passengers?                                     team-based decision making. At the same time, Openness,
                    b) optimizing a solution by evaluating different             Extraversion and Neuroticism are expected to be neutral
                          solutions and developing one proper solution           (indicated by the ‘n’ sign), based on Peters [20] who compared
                          together with the involved AOCC roles                  the personality profiles of an AOCC employee population
                    c) executing the solution by communicating a                 with a norm population.
                          decision to relevant stakeholders and applying
                          the decision                                                                               Quality service,
                                                                                                                    cost-effective and
                                                                                                                    minimal impact on
 Quality       Disruption management should allow to gain situation                      Technical                  network schedule                   Social
                                                                                                                                                     dimension
 description   awareness, identify, and understand the impact, make fast                 dimension

               decision by the controllers, but still ensure a quality service
                                                                                                       Timely available          Collaborative
               for passengers. The solution should be cost-effective and                                 information              team-based
                                                                                                                                decision making
               have a minimal impact on the overall network schedule,
               minimizing delays.
                                                                                                                                    Individual
B. Analyzing Quality Goals                                                                 Organizational
                                                                                               DNA                                 personality
                                                                                                                                                                             Team
                                                                                                                                                                           taxonomy

    The analysis of quality goals constitutes an important tool                                    <


for STS requirements analysis. According to Sterling and                                       n                          +/-                    n                     +/-                          n

Taveter ([13], p. 140), quality goals can contribute positively                     Openness
                                                                                                            Conscien-
                                                                                                                                  Extraversion             Agreeableness              Neuroticism
                                                                                                            tiousness
or negatively to the achievement of a functional goal. In
Figure 1, the quality goal On-time and with minimal
                                                                                 Figure 3. Social and technical dimensions of achieving the Manage
disruptions is associated with the functional goal Execute                       disruptions functional goal
network schedule, representing the positive plan at the
beginning of a day of operation. Figure 1 reflects that in case                  C. Role Models
of no disruption or minimal disruption, the following quality
goals contribute positively to the quality goal On-time and                          Role models describe each role of STS in terms of its
with minimal disruptions: Turnaround efficient and on-time;                      responsibilities and constraints required to achieve the goals
Aircraft legal and serviceable; Flight cost-effective, legal and                 of the STS. Role models belong to the viewpoint aspect of
on-time; Quality service, cost effective & minimal impact on                     organization analysis. Table IV contains the key
network schedule; Customer satisfied & revenue maximized;                        responsibilities and constraints for the roles needed for
Crew legal, sound and efficient. However, the situation                          achieving the goals of disruption management modelled in
changes in case of a significant disruption. In such a case, each                Figure 2.
of these quality goals can also exert a negative influence on                    Table IV. Role model for AOCC in case of disruption management
the achievement of the overall quality goal On-time and with
minimal disruption. The reason is that cost, time, and resource                   Role name                     Responsibilities                       Constraints
availability continuously stand in conflict which each other                      Operations                    Aircraft recovery:                     Dependency on
during a day of operation and such conflicts become critical                      Control                       Find options for                       maintenance based on
during disruption management. Handling conflicts in goal-                                                       alternatives                           availability of a substitute
                                                                                                                                                       aircraft or maintenance
oriented requirements is a separate issue that we have                                                                                                 resources and complexity of
addressed more in detail in [19].                                                                                                                      the required maintenance

    In the socio-technical context, it is interesting to further                  Crew Control                  Crew recovery: Find                    Crew duty times,
                                                                                                                alternative resources                  availability of stand-by
analyze how the technical and social dimensions may                                                             and keep crew duty                     resources, and dependencies
influence the achievement of the quality goals. Figure 3                                                        times legal                            on other flights
elaborates the social and technical dimensions of the quality                     Maintenance                   Aircraft: Ensure                       Availability of maintenance
goal Quality service, cost effective, and minimal impact on                       Control                       legality                               resources
flight schedule that is associated with the functional goal                       Ground Control                Turnaround process:                    Usually, the third party to
Manage disruptions. Each of the other quality goals could be                                                    Accelerate                             which the turnaround
                                                                                                                                                       procedure has been
elaborated the same way. The technical dimension is rather                                                                                             outsourced has no incentive
easy to grasp. If all technical systems deliver the information                                                                                        to speed up turnaround
in a timely manner and without failure, the overall impact of                     Passenger                     Passenger recovery:                    Availability of alternatives –
the technical dimension would be positive. The social                             Control                       Rebook and                             flights or accommodation.
dimension is much more complex. This is because the team                                                        accommodate                            Reputation is usually
                                                                                                                passengers                             negatively influenced
effectiveness framework, introduced in Section 2.3.1 of [18],
includes three factors which may enable or impede the overall                     Flight Dispatch               Flight plan: Speed                     A flight plan change should
                                                                                                                up en route                            be approved by the Air
effectiveness: team member characteristics (personality),                                                                                              Traffic Control
team-level factors (team taxonomy, e.g., cohesion), and
organizational or contextual factors (organizational identity,                   D. Organization Model
e.g., organizational structure of an airline). All these factors                     Organization model represents relationships between the
influence collaborative team-based decision making. As has                       roles. Organization models belong to the viewpoint aspect of
been concluded in Section 2.3.2 of [18], personality has a                       organization analysis. A relationship can be defined as a
considerable impact on team effectiveness. The Five-Factor                       control, benevolence, or peer relationship according to
Model (FFM) of personality profiles and particularly the                         Sterling and Taveter (([13], p. 75). Figure 4 represents the
organization model of the AOCC. The upper part of Figure 4                                                            Maintenance Control, and Passenger Control. All of them
shows the relevant contextual organizational roles Ground                                                             are peers to each other and are controlled by the Operations
Operations, Crew Operations, Flight Operations,                                                                       Control to maintain and control the day of operation. Flight
Maintenance & Engineering, and Revenue & Passenger                                                                    Dispatch is a special role because it has the peer relationship
Management.       These     contextual     roles    represent                                                         with all the other organizational roles. Additional sub-roles
organizational groups. They aggregate the key actors from the                                                         denoted by white-filled figures in the lower part of Figure 4
AOCC and outside actors related to the AOCC. The sub-roles                                                            are involved in a day of operation. They are essential for
of the AOCC denoted in Figure 4 by dark-filled roles include                                                          achieving the goals of the AOCC and disruption management
Ground Control, Crew Control, Flight Dispatch,                                                                        modelled in Figures 2 and 3.


                Ground                 Crew                                            Flight                                                         Maintenance &                              Revenue & Pax
               Operations            Operations                                      Operations                                                        Engineering                                Management




                                                                                             aggregation
                                                  aggregation                  aggregation                                                  aggregation
                                                                    aggregation                         Operations
                                                                                                         Control
                       aggregation                                                                                                                                                     aggregation


                                                 Crew                                                                                                Maintenance
                                                Control                                                                        isControlledBy         Control
                                                            isControlledBy                    isControlledBy

                                                                                                                     isControlledBy
                                                                                                                                                                      isControlledBy
                               isControlledBy
                                                                                                                              isPeer                                                            Passenger
                                                                                                                                                                                                 Control
                                                                  isPeer                                                         isPeer
                                                             isPeer
                    Ground                                                             Flight                                              isControlledBy
                    Control                                                           Dispatch

                                                                                                                                                                                     isPeer     isPeer
            isControlledBy isControlledBy       isControlledBy                                      isControlledBy




                                                                                Crew                             AirTraffic                 Line
                                                                               Member                            Controller                Forman
            Ramp                 Weight &                                                                                                                                    Gate                        Check-In
            Agent                Balance                                                                                                                                     Agent                        Agent
                                                                                         isBenevolentTo
                                                                                                                                           isControlledBy
                                                                                                                                                                                Legend
                                                           inheritance         inheritance
    isControlledBy               isControlledBy

                                                                                                                                                                                              AOCC Role
                                                                          isPeer                       isControlledBy
                                                                                                                                                                                              aggregation

  Fueling      Cleaning       Catering      Loading               Cabin            Cockpit                                     Tower             Line                                         inheritance
                                                                 Member            Member                                     Controller        Mechanic
                                                                                                                                                                                              relationship



Figure 4. Organization model of AOCC

E. Domain Model                                                                                                       controlled by the performers of different roles. For example,
    Domain model represents the domain knowledge to be                                                                the Maintenance Control System (MCS) is an information
stored and handled within STS. Domain models belong to the                                                            system overseen by Maintenance Control to track aircraft
viewpoint aspect of information analysis. Domain model                                                                health status and provide Operations Control with the
consists of domain entities and relationships between them                                                            information about the aircraft airworthiness and legality. The
([13], p. 76). The subject of the domain model represented in                                                         MCS also stores aircraft maintenance data, such as Minimum
Figure 5 is the knowledge shared and handled within the                                                               Equipment List (MEL) and Configuration Deviation List
AOCC. The AOCC domain model also includes the                                                                         (CDL), which are provided by a Crew Member before or
knowledge about disruptive events, their impact on cost and                                                           after the flight, or through a Line Mechanic during the line
time, and the potential solution developed to mitigate the                                                            maintenance checks. Finally, the MCS stores and provides
disruption. Additionally, the AOCC domain model represents                                                            information about the overall aircraft performance which is
technical systems – information systems – used by the AOCC                                                            being utilized by the Flight Dispatch during the flight
as resources, which are denoted in the figure as AOCC                                                                 planning process and is forwarded to another information
environments by underlying their names. Resources are                                                                 system – the Flight Planning System.
                                 Domain Entity                                                                                                                                                                                                              developes

                                                                                                                                                                                                                             Disruption Cost/
                                 Environment                                                                                                                                                       generates
                                                                                                                           Operations Control recognizes                                                                          Delay
            Role                                                                                                                       monitors
                           contain
                         relationship
                                                                                                                                                                                              Disruption                     Mitigates/solves
                                                                                                             Lies in              Network Schedule
                                                                                                                                                                  cues                    Management System
                                                                                                                                                                               lies in
                        relationship
                                                                     Cockpit Member
                                                                                                  A/C Movement                                                                                    Mitigates/
                                                       reviews                                    Control System                                                 Disruption Event                                          Disruption Solution
                                                                                                                                                                                                   solves
                                                                            accepts                                                      aggregation
             Airport Data
                                                                                                                       developes
              Schedule                                                             Updates status                                                               affects

                                                                          Operational            describes                                                 is assigned to                                                             Crew Control                  Signs-in
             Wx/NOTAM                analyses               calculates                                                                  Flight                                    Crew Roster                Lies in
                                                                           Flight Plan                                                                                                                                                   System
                Data
                                                                                                           approves
                                                                          files
                                         Flight Dispatch                                                                                                                                 tracks
                                                                                                                                                                                                                                                                       Crew Member
                                                                                                 ATC Flight Plan                   cleares
                                                                          developed                                                                                                                             developes
                     Situated in
                                                                                                                       informs                                                                                                                     developes
                                                                                                provides     accepts
                                                                         Flight Planning
               Fuel amount                      provides
                                                                             System
                                                                                                                                                         is assigned to        Crew Control                      Ground Control
                                                                                                                                    ATC                                                                                     overseas
                   provides                        inputs                                                                                                                                                                                            developes
                                                                             Used in
                                                                                                                                                                has                                     needs                                     involves
                                                                                               Used in                           Aicraft Performance                             Aircraft                                   Servicing
    Check-in Agent                                          Cargo Planner
                                                                                                                                      provides
                         Passenger data     Cargo load data                 Payload                                                                                  has                          reviews
                                                                                                                                                                                                                                                                  Fueling
  updates                                                                                                                    Maintenance Control                                                                                                                 Cleaning
                                                                                                               updates &           System                                                                                                                        Catering
                   commits              updates                                                                  tracks
                                                                             provides
                                                                                                                                                          Maintenance Data                        Line Maintenance                                               Loading
                                                                                                                                      Situated in                                                                                                                            updates
                                                                                                                                                             (MEL /CDL)
      Gate Agent                                                                           Maintenance Control
                                 Departure Computer
                                       System                                                                                                                                               updates
                                                                                      tracks
                                                                                                                                                                      developes
                                        provides
                                                                                                                Passenger Control
                                     Load & Trim
                    calculates                               executes                                                                                                            coordinates
                                        Sheet


   Weight & Balance                                                               Ramp Agent

Figure 5. Domain model of AOCC

              IV. FROM REQUIREMENTS TO DESIGN                                                                                      modelled by the corresponding subgoals Choose passenger
    As was stated in Section I, the requirements described in                                                                      option, Choose crew option, and Choose aircraft option. The
this paper serve the purpose of designing and implementing                                                                         roles responsible for achieving these goals are respectively
an agent-based simulation system [10] for the important social                                                                     Passenger Control, Crew Control, and Operations
part of the AOCC STS – AOCC employees responsible for                                                                              Control. Each of the subgoals is characterized by the
dispatching flights. As we pointed out in Section III.B, the                                                                       corresponding quality goals that are modelled from the
technical dimension of STS is rather straightforward, as it is                                                                     perspectives of the relevant roles. For example, the quality
embodied in the corresponding information systems, such as                                                                         goals Minimal passenger compensation, Protected passenger
various systems represented in Figure 5. Those systems make                                                                        and Minimal passenger delay capture the decision-making
recommendations for solving disruptions in one way or                                                                              criteria for choosing the passenger option from the perspective
another, effectively acting as decision-support systems. The                                                                       of Passenger Control. Figure 6 represents more elaborate
social dimension is much more complex because of the                                                                               options for each of the main solution types as lower-level sub-
inherent complexity of human decision-making processes.                                                                            goals under the second-level goals Choose passenger option,
Considering this, the design stage of our work is concerned                                                                        Choose aircraft option, and Choose crew option.
with designing simulation experiments to be performed with                                                                                              Minimal
                                                                                                                                                                                                                Develop
                                                                                                                                                                                                                solution

the social part of the AOCC STS. For this purpose,                                                                                                     passenger
                                                                                                                                                     compensation                                               Crew
                                                                                                                                                                                                               Control                                                       Protected

requirements for the greater STS described in Section III had
                                                                                                                                                                                                                                                                            schedule &
                                                                                                                                                                                     Minimal crew                                     Protected
                                                                                                                                                                                                                                                                         maximizedrevenue
                                                                                                                                             Protected                               delay & costs                                      crew
                                                                                                                                                               Passenger
to be represented and analyzed. Simulation experiments were
                                                                                                                                             passenger          Control                                                                                          Operations
                                                                                                                                                                                                                                                                  Control
                                                                                                                                                                                                                                                                                        Minimal flight
designed as agent-based simulations of the human subsystem                                                                               Minimal
                                                                                                                                        passenger
                                                                                                                                                                                                               Choose
                                                                                                                                                                                                             crew option
                                                                                                                                                                                                                                                                                        delay & costs


of the AOCC, where software agents performed the AOCC                                                                                     delay

                                                                                                                                                               Choose
roles that are usually performed by humans [18]. Since this
                                                                                                                                                                                                                         Use crew                                    Choose
                                                                                                                                                           passenger option                  Accept delay
                                                                                                                                                                                                                        on vacation                              aircraft option


paper is concerned with requirements engineering for STS, we                                                                                                Change pax on
                                                                                                                                                                                             Cancel flight
                                                                                                                                                                                                                        Use day off                    Swap
                                                                                                                                                            different flight                                                                                               Delay flight
next just briefly outline the steps of the simulation system                                                                                                 same airline
                                                                                                                                                                                                                          drew                        aircraft


design, leaving treating the simulations for a different paper.                                                                                             Change pax on
                                                                                                                                                            different flight
                                                                                                                                                                                            Proceed without
                                                                                                                                                                                                 crew
                                                                                                                                                                                                                       Exchange with
                                                                                                                                                                                                                       crew another                Reroute flight
                                                                                                                                                                                                                                                                              Book
                                                                                                                                                                                                                                                                            wet -lease
                                                                                                                                                             other airline                                                 flight

    To manage a disruption, there are three basic kinds of                                                                                                   Keep pax on                    Propose aircraft
                                                                                                                                                                                                                        Use nearest
                                                                                                                                                                                                                       reserve crew                                           Cancel
                                                                                                                                                                                                                                                     Join flights
solutions: passenger option, crew option and aircraft option.                                                                                               delayed flight                      change
                                                                                                                                                                                                                          at hub                                               flight



Those options are captured by the goal model shown in Figure                                                                                                 Cancel flight
                                                                                                                                                                                             Use crew with
                                                                                                                                                                                               free time
                                                                                                                                                                                                                        Use reserve
                                                                                                                                                                                                                         at airport

6, which elaborates the Develop solution functional goal
represented in Figure 2. In Figure 6, the three solutions are                                                                      Figure 6. Goal model for developing a disruption solving solution
The goal model shown in Figure 6 is crucial as the foundation
to develop the goal-driven behavior models of humans – the
AOCC personnel – for simulating the decision-making
process of disruption management. In Figure 6, some
functional goals, such as Cancel flight, appear under several
second-level functional goals. Since a given functional goal
has the same meaning, no matter where it is in a goal tree, the
decision to pursue one or another lower-level goal denoting a
particular disruption solution is made based on evaluating
how well the associated quality goals are met. By combining
functional goals and quality goals pertaining to some role,
such as Passenger Control, behavior models for agents
playing the corresponding roles were developed which
                                                                                Figure 7. Disruption solution matrix with the Cancel (C), Reroute (R), and
address the behavior perspective of the system design layer of
                                                                                Delay (D) options
the viewpoint framework shown as Table I. For executing the
behavior model, a scenario of disruption management was                         CONCLUSIONS
defined that offered three different simplified solutions –
cancel, reroute, and delay – to be chosen through collaboration                     This work discussed requirements engineering for
between the roles Passenger Control, Crew Control, and                          sociotechnical systems, using the example of the AOCC. We
Operations Control.                                                             specifically applied the viewpoint framework for ensuring
    For evaluating the achievement of the quality goals                         holistic requirements representation from complementary
defined for the corresponding roles, the agent cost function                    perspectives and represented the requirements by the models
was derived based on [21]. The function evaluates each                          included by the system analysis layer of the viewpoint
disruption management solution based on its cost and                            framework. The requirements analysis addressed the
probability of success. For choosing one or another solution                    organization, information, and behavior analysis viewpoint
based on the return value of the agent cost function, the agent-                aspects of the AOCC. The application of the goal-oriented
based simulation also considers the simulated FFM                               modeling approach allowed to differentiate between
personality profile of the AOCC decision-maker simulated by                     functional goals and quality goals. This is beneficial as
the agent. For example, whether the simulated decision-maker                    qualitative concerns could be matched to personality-driven
accepts the solution such as the passenger solution described                   behavioral patterns, which, in turn, could be mimicked by
in Table V, also depends on the FFM personality profile of the                  agent-based simulations. This is the main novelty of our
decision-maker, considering the goal-oriented planning                          approach, as this kind of agent-based simulation of a social
process of a human [22-24].                                                     part of STS has been done for the first time according to the
                                                                                best of our knowledge. Importantly, a prerequisite for
Table V. Interpretation of goals for the Passenger Control role
                                                                                adequate simulations of a social part is eliciting and
 Role       Func-      Quality           Plan              Solution             representing the requirements for the greater STS surrounding
            tional     goals             asses-                                 the social part to be simulated. Engineering requirements for
            goal                         sment                                  the greater STS is the main topic of this paper. Moreover, our
                                                  Cancel    Delay     Reroute
                                                                                approach allows to represent technical dimension of STS
 Pas-       Choose     Minimal           Proba-   Low       High      High
 senger     pas-
                       passenger
                                         bility
                                                                                equally well. For that matter, in the future work we plan to
                       compensation,
 Control    senger     Protected         Effort   Low       High      Med       model the technical part of the AOCC STS in more detail and
            option     passenger,                                               integrate into holistic modelling and simulation of decision-
                       Minimal
                       passenger delay                                          making processes within the AOCC. The result would be a
                                                                                simulation of the AOCC as a whole which can be used for
    In the simulations, qualitative values ‘low’, ‘high’ and
                                                                                exploring and optimizing the existing airline operations
‘med’ that were used in choosing a disruption solution, such
                                                                                control solutions by means of agent-based and other types of
as the passenger solution described by Table V, were
                                                                                computer-based simulations.
interpreted as quantitative values [18].
    Like the agent cost function for a human decision-maker,                    ACKNOWLEDGMENT
the system cost function represents the disruption solution                         The contribution by the second author to this publication
offered by the information systems of the AOCC. This way,                       has been funded by the IT Academy program of the European
we put equal weights on the disruption solutions of the STS                     Social Fund.
generated by (simulated) humans on one hand and (simulated)
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