Proactive flight schedule evaluation at Delta Air Lines

Delta Air Lines is the first and only airline to carry over 100 million passengers in a year, carrying over 105,000,000 passengers in 1998. To provide service to this number of passengers, Delta operates a "hub and spoke" flight system. In the hub and spoke system, certain key airports, or hubs, are designated as the origination point of a large number of flights, thereby allowing a passenger departing from a hub airport almost unlimited flexibility in terms of direct flight destinations. A change in the operation of the runways in one of Delta's hub airports was planned, and Delta management wanted to determine the effect on the dependable operation of the current and future flight schedules. Flight schedule dependability can be defined as the reliable, consistent, and timely operation of a published flight schedule. For several reasons, schedule dependability is absolutely critical to the successful operation of an airline. The airline industry is extremely competitive, and schedule dependability is an important benchmark that differentiates competing airlines in the eyes of many customers. Also, schedule dependability is critical to the profitability of an airline because of the high cost of an unreliable operation. These costs include repositioning aircraft, accommodating inconvenienced passengers, and adjusting pilot and flight attendant schedules. The purpose of this paper is to present two simulation models used to evaluate proposed flight schedules and to quantify the effect of changes in conditions at a major hub airport on the proposed schedule.