Metrics and methods of improving airline schedule reliability

Abstract

Airline scheduling is a daunting task. Much time and resources are spent by airlines developing a schedule that meets expectations of profitability and competitiveness. Most of the time, however, the reliability aspect has a minor, if any, role in such a process. In reality disruption of the schedule occurs due to unforeseen events such as weather conditions, traffic congestion, and mechanical problems. The outcomes of these events are cancellations and delays. The impact that these disruptions have on airline operations is not only the increased cost for system maintenance and recovery, but also the loss of profitability and the perception of poor and unreliable service for the flying customer. In this thesis we present an analysis of the schedule design process, highlight the drawbacks of the current proceedings and outline of new and more flexible framework for schedule design. We define a reliability measure, the Option Value, and a way of comparing flights based on the reliability they are providing, via the Option Disruption Value. The idea of reliability is based on the concept of flight performance: a flight is more reliable if it is able to match or outperform the on-time performance of the flights that leaves its origin station and arrives at its final destination at or near its arrival and departure times. Based on these two measurements, we quantify the robustness and coverage of a sample schedule. Alternative passenger ratings are defined based on the concept of alternative itineraries (Coverage) and alternative independent itineraries (Robustness) that connect two locations. These are the Flight Options and the Flight Protection Options, respectively. Fifteen methods to modify flight schedule are proposed. One method, Reduce/increase Flight Slack Time (R/IFTS) was evaluated. Results indicate that R/IFTS was effective in increasing reliability in 70% of the flight considered, but that other methods need to be employed if reliability is to be increased further.