In this paper, the heterogeneity in passengers' perceptions of airlines' services has been investigated by using a Random Parameter Mixed logit model. To calibrate and validate the proposed model, data from a Stated Preferences choice experiments was used. The survey was conducted online and involved the whole population of the University of Calabria (Italy). The experiments were designed by considering the main service attributes characterizing air travellers’ experience in its entirety: before, during, and after the flight. Differently from the previous studies using Stated Preferences survey, two different groups of choice experiments were designed: the former referring to before/after the flight stages, and the last referring to during the flight experience. For each group, specific attributes were considered.Final findings remark that flyers' perceptions on airline's services vary among the different service aspects and among individuals. Specifically, we found that curtesy of cabin crew, space available, temperature, cleanliness, service on board and ticket cost are attributes referring to the during the flight stage of the travel that showed heterogeneity in passenger's perceptions. On the contrary, the attributes referring to the before/after the flight stages for which we detected heterogeneity in passengers' perceptions are waiting time at check-in, delay of flight departure, and ticket cost.