Development of flight leg robustness index and its application in robust crew scheduling

Disruptions are inherent in airline operations. Their huge impact on airline economics due to their high frequency and size of disruption has emphasized the need to develop robust schedules. This dissertation presents a new methodology that creates more robust airline crew schedules by taking historical performance into consideration. The research is motivated by the fact that effects of disruptions are associated with the qualities of a flight leg. These qualities have been identified and their relationship with various causes, flight phase, and duration of the disruptions are described. A new performance measure defined as Flight Leg Robustness (FLR) Index is developed using this relationship which has applications in recovery policies evaluation and robust operations planning. The historical performance is analyzed to determine suitable crew duty times which can compensate for the delay duration in the previous flight legs. The flight leg based approach developed in this research reduces propagated delays, does not increase crew costs dramatically as is anticipated from robust crew schedules and is able to contribute to aircraft utilization which contributes to airline fleet costs.