Air traffic management: evolution with technology

One of the remarkable features of ATM systems from a control perspective is that there is no tolerance for system shutdown and start-up. The system literally must operate 24 hours per day, seven days per week. It is not feasible to simply shut down an old system and start up a new one. The economic and social costs of declaring that one day will be a day with no air traffic while the systems are switched are simply prohibitive. ATM, at least as far into the future as we can imagine, is a system with essential human and machine components. It is inconceivable that either component will ever disappear. Yet, as the system evolves, there are continual changes in the way work is shared between human and machine. Provision for such flexibility is an essential requirement for any proposed new system. New technologies are driving the ATM paradigm from command and control in the direction of more distributed decision making. This may be best illustrated by TCAS (the Traffic Alert and Collision Avoidance System). TCAS is a tactical system intended for use by pilots to avoid collisions caused by inadvertent violations of separation standards. It displays to the flight crew specific information about certain nearby aircraft and, depending on the likelihood of conflict, provides advice for actions needed to avoid collisions. Details of TCAS are given in the article