The automatic estimation of the actual traffic situation on airports is becoming ever more important with the increase of traffic flow. A method to model and to integrate the airport topography and topology into the traffic situation estimation process is presented in the paper. A certain abstraction of the state description of a traffic object from mathematical coordinates to higher level functional airport elements is obtained as a positive side effect. A filtering algorithm, based on the advanced Interacting Multiple Model approach to hybrid systems estimation is proposed. It performs better than standard Kalman filter solutions. The proposed method is computationally more complex than standard solutions.