The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years the evolution in ConOps has resulted in changes in the ATM′s physical architecture,improving its physical infrastructure,increasing the levels of automation and making operational changes to improve air traffic flow,to cope with increasing demand for air travel.However,what is less clear is the impact of such changes in ConOps on the ATM′s functional architecture.This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions.This paper reviews the changes in the ConOps over the years,proposes a temporally invariant ATM functional model,and discusses some of the main key technologies expected to make significant improvements to the ATM system. The air traffic management system (ATM) has the task of ensuring safe, orderly and expeditious flow of air traffic. ATM system architecture is very much dependent on on the concept of operations (ConOps) .Over the years the evolution in ConOps has resulted in changes in the ATM’s physical architecture, improving its physical infrastructure, increasing the levels of automation and making operational changes to improve air traffic flow, to cope with increasing demand for air travel.However, what is less clear is the impact of such changes in ConOps on the ATM’s functional architecture. This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions. This paper reviews the changes in the ConOps over the years, a temporally invariant ATM functional model, and discuss some of the main key technologies expected to make significant improvements to the ATM system.