ASSESSING THE BENEFIT OF INNOVATIONS IN ATC

Recent advances in technology have encouraged proposals for new approa ches to ATC in Europe and elsewhere. Two such proposals, both rather l oosely framed, are for 'free flight' or for 'seamless contracts'; othe rwise 'tubes of flight'. These concepts, and variations on them, aim t o increase the traffic capacity of the airspace. They have been the su bject of numerous published papers. Given the declared objects of thes e systems, it is surprising that, nearly without exception, these pape rs discuss the proposals only in qualitative terms. The present paper discusses idealised versions of these systems on the basis of quantita tive studies. It is concluded that the 'seamless contract' is very pro bably unworkable in Europe. 'free flight' is workable in principle, bu t there is a need for investigation of possible mechanisms by which la st-minute problems may be resolved.