Flight Scheduling Case Study

Our study reviews flight scheduling, aircraft-path assignment and gate assignment. Fig. 1 shows these activities. We adopted the study of Barnhart and Cohn (2004) for these activities. The first stage includes gate assignment and flight scheduling, because they have close interaction with each other. Gate assignment defines a gate for each flight. The gates are not available at any given time. Flight scheduling determines the departure and arrival times for flights. The second stage is aircraft assignment. This stage assigns aircrafts to flights. The third stage is path assignment. Path assignment attempts to assign the maximum path to one aircraft for maximizing its use during the planning horizon. The integration of above activities is NP-hard

He introduced this time as an important factor for passengers’ satisfaction. Passengers expect a shortest cruise flight time. If an appropriate response given to the expectations, then passengers’ satisfaction will increase. Second: various factors are involved in the incident during a flight. By studying these factors, Skorupski (2015) estimated the probability of an incident during the cruise flight time. This probability is equivalent to 1.55×10-8 in a flight hour. We considered this value as γ. Reducing the cruise flight time can reduce the risk of accident. This will increase the flight safety as an effective factor in passenger service level (Hussain et al., 2015). The above viewpoints show the significance of cruise flight time in passenger service level. Therefore, we have decided to bring up the cruise flight time as one of the passenger service level indicators. The first term in (2) seeks to reduce the cost of cruise flight time. Decreasing the cost of cruise flight time is equivalent to increasing passenger service level. We have decided to bring up the walking distance as other passenger service level indicators. Lacking attention to gate assignment can increase the passenger walking distance and its dissatisfaction. With proper gate assignment, this threat can transform into an opportunity to attract passengers’ satisfaction. The second term in (2) minimizes the passenger

Constraints (4) - (6) plan some flights consecutively by one aircraft. These flights are the members of the set that a flight destination is the same as origin of another flight. We extended the planning horizon to few days and develop a new approach in its modeling. This issue has led to the creation of constraints (7) - (13). In the proposed approach, it is necessary to know the first and last flights of aircrafts in each day. Constraints (7), (8) and (10) find the first flight performed by each aircraft in each day. Constraints (7), (9) and (11) find the last flight performed by each aircraft in each day. Constraint (12) calculates σ_td. If aircraft t performs only one flight on day d, then constraint (13) considers this flight as the first and the last flight for aircraft t on day d. If aircraft t performs more than one flight on the day d, then constraint (13) does not consider each of these flights simultaneously as the first and the last flight for aircraft t on day d. Constraint (14) is necessity to know the first and the last flight of aircrafts in each day. This constraint stating the last destination of aircraft t in a day is the same as the first origin of aircraft t in the next day. There is a curfew time in some airports due to the security issues and military regulations (Hu et al., 2016). Constraints (15) and (16) apply the time limit for flights.