The European Air Traffic Control system (ATC) has entered a deep crisis : this system is unable to meet atremendous increase in the demand. This is not only the consequence of its inertia ; such inertia is normal forany complex system. Short term measures to optimize the present tools appear to be insufficient : these toolshave already reached the limits of their development capability. A wide−ranging discussion, on how toenhance ATC methods and tools, has begun. Very ambitious goals have been set for the future systems : forexample the French CAUTRA V project plans to double the capacity of the system by the year 2005 and tosignificantly increase safety. Numerous ambitious projects exist, but none of them has yet proved itsefficiency or even its feasibility. ATC automation is really short of effective solutions.