Intent inference involves the analysis of actions and activities of a target of interest to deduce its purpose. This paper proposes an approach for intent inference based on aircraft flight profile analysis. Simulation tests are carried out on flight profiles generated using different combinations of flight parameters. In each simulation test, Interacting Multiple Model-based state estimation is carried out to update the state vectors of the aircraft being monitored. Relevant variables of the filtered flight trajectory are subsequently used as inputs for a Mamdani-type fuzzy inference system. Research on two applications is reported. The first application involves the determination of the likelihood of weapon delivery by an attack aircraft under military surveillance. Test results verify that the method is feasible and is able to provide timely inference. By extending the method to take the environmental context of the tracked aircraft into consideration when executing the inference process, it is likely that the military defenders would be able to raise their alert earlier against potential adversaries. This would provide them with more time to react and devise pre-emptive counteraction. The second application concerns conformance monitoring in air traffic control systems. Experimental results show that the proposed solution can be used to assist air traffic control system operators in determining if aircraft navigate according to planned trajectories. Consequently, corrective action can be taken on detection of anomalous behavior. A brief discussion on extending the proposed method to deal with multiple aircraft is also presented.