As an emerging IT implementation, big data brings new challenges to the development of aviation industry, meanwhile exerting a profound influence on the IT industry revolution. The huge amount of data generated from aircraft operation is the best representation of the big data gene of aviation. The aircraft operational support based on big data would be one of the main fields of its ambitious applications. This paper firstly teases out the data category, data structure, data flow as well as data property through the analysis on the operational big data. Considering the specific requirements from airlines, three key techniques including fault diagnosis, degradation prediction for some typical complex systems and maintenance decisionmaking are investigated as big data applications. Advanced data mining and machine learning methods will be used for feature expression of the operational data under different system health conditions as well as early warning models of some deterioration systems with potential faults. Lastly, the big data system and the operational workflow based on big data are discussed from the perspective of engineering application.