Challenges of Building Robust Plans Lack of a systematic way to define robustness in the context of airline schedule planning Aircraft, crew and passenger flows interact in the hub-and-spoke network Huge problem size> tractability issue Difficult to balance robustness and costs 1010 Challenges of Building Robust Plans Lack of a systematic way to define robustness in the context of airline schedule planning Aircraft, crew and passenger flows interact in the hub-and-spoke network Huge problem size → tractability issue Difficult to balance robustness and costs