In this book, we present graph theoretical analysis of two air transportation networks, Airport Network of India and World Airport Network. The heterogeneity in connectivity and long-range couplings observed in these networks suggest that certain nodes may play an important role in maintaining the stability and efficient flow through the network. Identifying and analyzing the impact of targeted removal of such “critical” nodes on the network is the major focus of this work. In this study we show the importance of network theory in applications such as improving air connectivity to promote tourism, identifying crucial airports and routes to regulate traffic in case of emergencies such as accidental failure of an airport, identifying routes for diverting traffic to avoid congestion/delay during unexpected climatic changes, and in containing the spread of disease through the air transport network. To better understand the evolution of these transportation networks, we also attempt to model the growth of air transportation networks in this study.