Inappropriate gate assignment has some consequences such as flight delays, inefficient usage of resources and customer’s dissatisfaction. Airports are service sectors and provide services to their customers. Passengers and airlines are two main customers of an airport. Current research presents a novel mathematical model for gate assignment problem to minimize customers’ dissatisfaction. In other words, passengers walking time as well as flight delays are minimized in as objective function. In this model, transit and non-transit passengers and also arrival and departure flights are considered. Moreover, operational safety constraints are inserted to avoid collision of large aircraft. The proposed model is solved by Benders decomposition approach. The model is applied in San Francisco International Airport for a 24-hour horizon. The result shows that walking time of non-transit passengers, walking time of transit passengers, delay in departure flights and delay in arrivals include 74.55, 23.32, 0.96 and 1.17 percent of the objective function, respectively. Manuscript profile