The main objective of this paper is to determine the key factors affecting passengers' domestic airline choice in Turkey. This study utilized thedata of a self-administeredsurvey conducted to 2473 passengers in 11 different airports. The data were analyzed using multinomial and mixed logit (ML) models. The analysis results reveal that ML model is useful to explain preference heterogeneity of passengers' airline choice behavior. The estimation results also indicate that several demographic, socio-economic, and travel destination characteristics were found as the significant drivers of passengers' airline choice. The results of this study may be a valuable tool for policy-makers in the airline industry.