Air traffic management (ATM) aims at ensuring the safe and efficient flow of air traffic. It encompasses three types of services:air traffic services (ATS) including air traffic control (ATC), air traffic advisory services, flight information services and alerting services, airspace management (ASM), the purpose of which is to allocate air routes, zones, flight levels to different airspace users and the airspace structure, and air traffic flow and capacity management (ATFCM) consisting in regulating the flow of aircraft as efficiently as possible in order to avoid congestion in airspace and airports.