This paper aims at assessing the impacts of recent economic liberalisation on an important subset of the Brazilian airline industry: the air shuttle market on the route Rio de Janeiro – São Paulo, a pioneer service created in 1959. In order to estimate structural relationships of the competition model, a product differentiated setting with conduct parameter was designed. Results permitted inferring about a rupture in the degree of firms' heterogeneity and in the extent of the deviation from Nash behaviour due to regulatory reform, as well as estimation of pertinent route-level cost information.