This book explores how to improve capacity and relieve congestion of modern-day air traffic and to increase the ability for mobile aircraft to communicate efficiently with ground networks. It emphasizes the advances, challenges, and modeling of ATN. The book covers MIPv6 as a core of mobility management mechanism for the aeronautical environment. It examines the simulated performance of VDL Mode 2, investigates the ATM system cyber-attacks since 9/11, and examines the current security situation of ATM information systems related to safety in air transportation.