Browsing by Subject "Air traffic control."

Now showing 1 - 4 of 4

Open Access
An application of stochastic programming on robust airline scheduling
(2014) Karacaoğlu, Nil
The aim of this study is to create flight schedules which are less susceptible to unexpected flight delays. To this end, we examine the block time of the flight in two parts, cruise time and non-cruise time. The cruise time is accepted as controllable within some limit and it is taken as a decision variable in our model. The non-cruise time is open to variations. In order to consider the variability of non-cruise times in the planning stage, we propose a nonlinear mixed integer two stage stochastic programming model which takes the non-cruise time scenarios as input. The published departure times of flights are determined in the first stage and the actual schedule is decided on the second stage depending on the non-cruise times. The objective is to minimize the airline’s operating and passenger dissatisfaction cost. Fuel and CO2 emission costs are nonlinear and this nonlinearity is handled by second order conic inequalities. Two heuristics are proposed to solve the problem when the size of networks and number of scenarios increase. A computational study is conducted using the data of a major U.S. carrier. We compare the solutions of our stochastic model with the ones found by using expected values of non-cruise times and the company’s published schedule.
Open Access
Fleet type assignment and robust airline scheduling with chance constraints under environmental emission considerations
(2013) Şafak, Özge
Fleet Type Assignment and Robust Airline Scheduling is to assign optimally aircraft to paths and develop a flight schedule resilient to disruptions. In this study, a Mixed Integer Nonlinear Programming formulation was developed using controllable cruise time and idle time insertion to ensure passengers’ connection service level with the objective of minimizing the costs of fuel consumption, CO2 emissions, idle time and spilled passengers. The crucial contribution of the model is to take fuel efficiency of aircraft into considerations to compensate for the idle time insertion as well as the cost of spilled passengers due to the insufficient seat capacity. The nonlinearity in the fuel consumption function associated with controllable cruise time was handled by second order conic reformulations. In addition, the uncertainty coming from a random variable of non-cruise time arises in chance constraints to guarantee passengers’ connection service level, which was also tackled by transforming them into conic inequalities. We compared the performance of the schedule generated by the proposed model to the published schedule for a major U.S. airline. On the average, there exists a 20% total cost saving compared to the published schedule. To solve the large scale problems in a reasonable time, we also developed a two-stage algorithm, which decomposes the problem into planning stages such as fleet type assignment and robust schedule generation, and then solves them sequentially.
Open Access
An object-oriented simulation model for airport traffic control
(1995) Yıldırım, İnanç
In recent years airport congestion and delay problems have received a great deal of attention due to the rapid growth of air transportation services. Of all the elements contributing to the air terminal congestion, the Air Traffic Control problem is the best understood. In this thesis we present an object-oriented model for simulating air traffic flow at an airport. The application of objectoriented design to the simulation model construction process is identified as a need, particularly for modeling large and complex systems. Object-oriented paradigm has already demonstrated that it can help to manage the growing complexity and increasing costs of the software development. The model we present here, has been implemented on a personal computer by illustrating a major metropolitan airport.
Open Access
Robust airline scheduling with controllable cruise times and chance constraints
(2012) Duran, Aslıgül Serasu
This is a study on robust airline scheduling where flight block times are considered in two parts as cruise time and non-cruise time. Cruise times are controllable and non-cruise times are random variables. Cruise time controllability is used together with idle time insertion to handle uncertainty to guarantee passenger connection service levels while ensuring minimum costs. The nonlinearity of these cost functions are handled by representing them via second order conic inequalities. The uncertainty in non-cruise times are modeled through chance constraints on passenger connection service levels, which are expressed using second order conic inequalities using the closed form equations. Congestion levels of origin and destination airports are used to decide variability for each flight. Computational study shows exact solutions can be obtained by commercial solvers in seconds for a single hub schedule and in minutes for a 4-hub daily schedule of a major US carrie