Seminar by
M. Selim Akturk
Department of Industrial Engineering
Bilkent UniversityAlthough the airline industry is very successful in implementing optimization tools for the planning and scheduling of their resources, they are facing significant problems to deal with the disruptions in their daily operations due to unexpected aircraft maintenance requirements or undesirable weather conditions. In this presentation, I first propose a novel rescheduling optimization model that explicitly accounts for delay as well as fuel burn and CO2 emission costs by incorporating cruise speed control into airline disruption management. Flight time controllability and nonlinear delay, fuel burn and CO2 emission cost functions complicate the aircraft recovery problem significantly. We utilize the recent advances in conic mixed integer programming and propose a strengthened formulation in mitigating this difficulty so that our proposed nonlinear optimization model could be used by operations controllers to deal with disruptions in real time in an optimal manner instead of relying on heuristic approaches.
On the other hand, robust airline schedules could be viewed as to generate flight schedules that are likely to minimize passenger delay. Airlines usually add an additional time, e.g. schedule padding, to scheduled gate-to-gate flight times to make their schedules less susceptible to the variability and disruptions. There is a critical tradeoff between any kind of buffer time and daily aircraft productivity. The uncertainty in flight times are modeled through chance constraints on passenger connection service levels, which are expressed using second order conic inequalities. Aircraft speed control is a practical alternative to inserting idle times into schedules. Overall, 60% saving of idle time costs could be obtained by a 2% increase in fuel costs. Our computational study shows that exact solutions can be obtained by commercial solvers such as CPLEX in seconds for a single hub schedule and in minutes for a 4-hub daily schedule of a major U.S. carrier.
This is a joint work with Prof. Alper Atamturk from UC Berkeley, Prof. Sinan Gurel from METU, and A. Serasu Duran from Northwestern University.
Biographical Sketch
M. Selim Akturk is Professor of Industrial Engineering at Bilkent University, Turkey. During his sabbatical leaves, he worked as a visiting professor at McGill University, Carnegie Mellon University and University of California at Berkeley. His current research interests include production management systems, aviation applications, and scheduling. The first part of this presentation received the `Best Technical Paper` award in 51st Annual Symposium of Airline Group of the International Federation of Operational Research Societies (AGIFORS) in 2011.
