The scope of the air-ground data links, which have been developed over the last ten years to meet the airlines' operational requirements, will be extended in future years.

Air traffic control is one of the fields which will certainly make extensive use of this type of link. Indeed, it appears to be necessary to deal with the problem of traffic saturation globally by taking account of the navigation capabilities of modern aircraft as regards precision and the considerable automated flight/ground exchange possibilities which will be provided by future telecommunication networks.

The contents of the messages exchanged between aircraft and air traffic control centres, and the interfaces with the human operators concerned, i.e. pilots and controllers, must form the subject of thorough investigations conducted with all the parties involved: constructors, equipment manufacturers, traffic control organisations, and airlines. Aerospatiale have already taken this problem into account in the various studies being performed within the framework of the PREFACE and FANSTIC programmes.