The goal of the study is to analyse the performance of the Aeronautical Billing System of the Athens International Airport. Recommendations for the system improvement are made. He first part of the work maps the billing process assuming that no billing system exists. For the analysis, UML technique had been applied. The second part presents how the current billing system using UML technique supports the billing process. Flow of data and sequence of required tasks for execution of the billing process are discussed in this part of the work. Next, daily tasks performed by end-users within the ABS software are presented. In order the performance of the current billing system to be evaluated, QF2D technique had been used. Comparing the billing process flow with operation of the current billing system helped for preparation of an appropriate questionnaire. Data needed for assessment of the system was also collected through the interviews with ABS end-users. Finally, after evaluating the performance of the system, numerous improvements related to the functionalities of the system and software characteristics, which would contribute to increase the user satisfaction, are identified
