Depeaking – economic optimization of air traffic systems

More than half of all flights in and out of Frankfurt International Airport are conducted by Lufthansa airlines, as it is one of their two major hubs. The so called hub and spokes systems allow airlines to bundle major passenger flows via connecting flights across the in- and outbound traffic. The reliability of these transfer connections, and specifically the arrival punctuality at the hub airports are crucial to the economics of the daily operation.Since Frankfurt International Airport has lately been one of the most congested airports in Europe, delays (in particular arrival delays) have increased quite significantly throughout the last years. To compensate for additional queueing time in the arrival processes, the scheduled block times inbound Frankfurt were continuously adjusted upwardly keeping the arrival punctuality (and thereby the connection reliability) close to stable. The two disadvantages of this approach have been the decrease in aircraft productivity and over-deliveries in peak hours, which in turn induce either additional block time delay or ground delay programs inbound Frankfurt.This paper introduces an iterative stochastic-simulation approach that models the vicious circle of lengthening block times and increased over-deliveries. In a second step it quantifies the operational and economical effects of depeaking the schedule and illustrates the overall growth potentials for the depeaked operation of the airport. The schedule was successfully implemented in Frankfurt in summer 2004.