The flights'' departure time setting is the critical work of the flight timetable construction, and a well-planned flight timetable can provide higher revenues or lower costs for airlines. The flight timetable construction should be based on demand pattern. However the market demand pattern viewing from flights load is a result of the passengers choice under a well-known flight timetable. There is a difference from the actual air travel demand pattern that means the number of desired departure passengers in each time point. Although actual travel demand may be obtained through a survey conducted on passengers, such a survey takes up enormous manpower and time; moreover time and space changes may render the findings useless. The acquisition of a reasonable estimation of the actual passenger travel demand by simplified data is an important issue for flight timetable construction. Flights remain to be a very important attraction in the flight choice consideration of passengers. Hence the flight load is influenced from competition. Flight load estimation should be the basis for the airline to set the flight departure time. Lack of sufficient studies in flight departure time setting and the inability to coordinate schedules with short-distance domestic flights make it imperative to develop studies in this area.
This study traces the market development, supply-and-demand conditions, as well as the passengers questionnaire date survey analysis to classify market characteristics. We analyzed the domestic air passenger choice behavior and consideration factors, and assumed that passengers would choose flights under an acceptable time period. This constitutes the air passenger choice model and the probability to choose flights in each time point. Then the flight load estimation may be gathered from the choice passenger of each time point. A flight load estimation model is developed from this exercise.
Although the actual desired departure passenger of each time point is known, the actual passenger load of each flight is observable. Hence our study used the dynamic recursive estimation method to estimate the actual travel demand through the errors of estimation flight load and observation flight load and to revise them iterated. Otherwise, since the flight load estimation model used can estimate the probable passenger load of each time point, a flight departure time setting concept is formulated as a binary integer programming model subject to the fleet size and service flight frequency. Since the flight departure time problem has some good characteristics available, with the help of the very useful information, an efficient algorithm which can solve the problem without too much difficulty is thus proposed.
The results from the analyses have revealed that the estimation load errors is less than 20-passengers in majority of the flights, and almost 50% of the flight estimation load error is under 10 passengers. This shows a very high accuracy rate. The estimation error is mainly due to the inability to fully explain the actual passengers behavior in the passenger choice model, as well as the every day regular flight load changes. The varying initial value setting can still provide the closest demand results, a manifestation of the applicability of the recursive estimation model and the high accuracy rate of the actual travel demand obtained from the estimation. The sensitivity analysis results show that ticket price changes have a significant effect on flight load. Analysis of the influence of different flight departure time alteration on flight load may also serve as a reference for the flight departure time adjustment considerations of airlines. Furthermore, the estimation parameter value in passenger choice utility function for passengers to early arrival is less then to late arrivals. This shows that domestic flight passengers prefer the early arrival flight to late arrival flight under the same time difference between passenger desired departure time and flight departure time.