A PETRI NET FRAMEWORK FOR THE REPRESENTATION AND ANALYSIS OF AIRCRAFT TURNAROUND OPERATIONS Zheng Yang Sng and R. John Hansman This report is based on the Master’s Thesis of Zheng Yang Sng submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science in Transportation at the Massachusetts Institute of Technology. Report No. ICAT-2019-05 June 2019 MIT International Center for Air Transportation (ICAT) Department of Aeronautics & Astronautics Massachusetts Institute of Technology Cambridge, MA 02139 USA 1 [Page Intentionally Left Blank] 2 A Petri Net Framework for the Representation and Analysis of Aircraft Turnaround Operations by Zheng Yang Sng Submitted to the Department of Civil and Environmental Engineering on May 17, 2019, in partial fulfillment of the requirements for the degree of Master of Science in Transportation Abstract Aircraft turnaround operations is a key determinant of both airline and airport performance. Airlines incur both direct and indirect costs from poor on-time departure performance, particularly when these delays propagate through an airline’s schedule and additional resources have to be utilized for schedule recovery. As for airports, poor stand utilization due to excessive stand occupancy times can give rise to stand shortages and last-minute reallocations which disrupt operations across both terminal and airside. As such, optimization of aircraft turnaround operations provides opportunities for improvements at a systemic level. Petri Nets were chosen as the modelling tool as they possess features which can sufficiently account for both the complexity and uncertainty associated with aircraft turnarounds. Petri Nets models were first constructed to provide general representations for the turnaround operations of narrow-bodied B738 and wide-bodied A333 aircrafts. The Petri Nets were then adapted to make provisions for operational procedures specific to Changi Airport Singapore, the case study for this paper. The rationale for this 2-step process is to facilitate reusability of the proposed framework as the Petri Nets can be adapted to fit different contexts. After the Petri Nets were calibrated using empirical data, Monte Carlo simulations were performed. Critical path analysis was then conducted for characterization of existing operations. For B738, critical paths involving passenger services and fueling-related activities dominated. For A333, critical paths involving passenger services as well as fueling-related and catering-related activities dominated. Different modifications were then added to the Petri Nets and subsequently evaluated for their potential to reduce stand occupancy times through additional rounds of simulation. Different combinations of modifications involving automated aerobridge operations and removal of passenger deboarding as a precedent constraint for fueling-related and catering-related activities achieved noticeable reductions in stand occupancy times for B738 and A333. The potential reductions in stand occupancy times from improved scheduling outcomes were also analyzed. Thesis Supervisor: R. John Hansman Title: T. Wilson Professor of Aeronautics and Astronautics 3 4 Acknowledgments First and foremost, I would like to thank my advisor, Professor John Hansman, for his support and guidance throughout the entire project. His insights have been invaluable in helping me refine my approaches towards conceptualizing and solving problems. Second, I would like to thank CAG and dnata for providing access to data that made the analysis in this thesis possible. More specifically, I would like to extend my appreciation to all the airport and ground handling managers over at CAG and dnata who have been extremely patient and helpful in providing in-depth tours while on-site at Changi Airport, as well as support over the course of the project. Third, I would also like to thank Mr Paul Tan from ST Engineering for the sharing of his insights on automated aerobridge operations. Finally, I would like to thank my family and friends back home for their unwavering support, without which this final product would not have been possible. 5 6 Contents 1 Introduction ........................................................................................................................... 19 1.1 Motivation ...................................................................................................................... 19 1.2 Research Objectives and Scope...................................................................................... 19 1.3 Thesis Outline ................................................................................................................ 20 2 Background ........................................................................................................................... 21 2.1 Aircraft Ground Handling Activities.............................................................................. 21 2.1.1 Ramp Services ......................................................................................................... 22 2.1.2 Above-the-wing Activities ...................................................................................... 23 2.1.3 Under-the-wing Activities ....................................................................................... 25 2.3 The Aircraft Stand as an Interface for Terminal and Airside Operations at the Gate .... 27 2.3.1 Physical Layout and Movement of Resources for Exchange of Key Elements ...... 27 2.3.2 Relationship between Aircraft Ground Handling Activities with Airside/Terminal Operations ......................................................................................................................... 28 2.3.3 Convergence of Terminal and Airside Operations at the Gate ................................ 29 2.4 Literature Review ........................................................................................................... 31 3 Methodology ......................................................................................................................... 32 3.1 Petri Nets as the Choice of Modelling Tool ................................................................... 32 3.2 Case Study ...................................................................................................................... 33 3.3 Data Collection ............................................................................................................... 33 4 Case Study: Changi Airport Singapore ................................................................................. 36 4.1 Overview of Ground Handling Departments and Facilities of dnata Singapore Ptd Ltd .............................................................................................................................................. 36 4.1.1 dnata Ramp Facility ................................................................................................. 38 4.1.2 dnata Resource Planning Facility (Manpower Scheduling for Ramp Services) ..... 38 4.1.3 dnata Cargo Facility................................................................................................. 38 4.1.4 dnata Catering Facility............................................................................................. 39 4.1.5 Baggage Handling Facilities .................................................................................... 40 4.1.6 dnata Customer Services (Terminal-side Passenger Handling Services) ................ 40 4.2 Operational Procedures .................................................................................................. 40 4.2.1 Operational Procedure for B738 .............................................................................. 40 4.2.2 Operational Procedure for A333.............................................................................. 42 4.3 Tracking of Turnaround Progress under the Airport Collaborative Decision Making (A- CDM) Framework ................................................................................................................ 44 5 Petri-Net Modelling .............................................................................................................. 46 7 5.1 Petri Nets for B378 Turnaround ..................................................................................... 46 5.1.1 Master Net for B738 Turnaround ............................................................................ 47 5.1.2 Modelling of Specific Features................................................................................ 49 5.1.3 B738 Master Net Adapted for dnata-specific Manpower Dependencies ................ 56 5.1.4 Manpower Dependencies of dnata for B738 ........................................................... 58 5.2 Petri Nets for A333 Turnaround..................................................................................... 61 5.2.1 Master Net for A333 Turnaround ............................................................................ 61 5.2.2. Notable Differences from B738 ............................................................................. 63 5.2.3 A333 Master Net Adapted for dnata-specific Manpower Dependencies ................ 67 5.2.4 Manpower Dependencies of dnata for A333 ........................................................... 69 6 Monte Carlo Simulation Using Petri Nets ............................................................................ 72 6.1 Petri Nets as a