In recent years; the airline transportation sector that is affected by globalization is witnessing dramatic change and international travels that have both touristic and business purposes are increasing. This increase leads to change in the passengers' profile in the air transportation. The new market structure and intense competition cause to change service quality expectations of passengers. To gain competitive advantage in the air transportation requires learning customers' expectations, meeting these expectations, and providing customer satisfaction. In this study, in order to understand thoroughly the relation between perceived service quality and customer satisfaction; the effects of service quality perceptions of passengers on customer satisfaction are examined. In the research, 511 passengers are interviewed at the external flights of X Airlines. The results of the analysis reveal the fact that prompt service is the most effective factor on the passengers' overall satisfaction level. The other factors effecting passengers' overall satisfaction level are respectively: reliable and accurate service, assurance and understanding the customer.