This study traces to determine the internal customers in air traffic control services by using INTQUAL Scale I. In this study, the research method of another study was adapted to the new sector. New questionnaire statements were added. Hence, the dimensions of INTQUAL were changed. Air traffic control system works as a service manufacture system. In this regard, a questionnaire was prepared and applied to the air traffic controllers that work in the 3 international airports in Turkey. Some air traffic controllers that work in same operation feels less satisfied than the others. Also, there is same conclusion in different air traffic control units, too. In previous years, there is no study about air traffic controllers as this study. It is necessary to make the study like that for both providing improvement about the salary regulations and controllers’ work conditions.