The Air Transport industry is passing through a period of profound change, as the writers of both prefaces have emphasized. This evolution requires a major reorientation of attitudes and expectations, and a major redirection of the focus of our concerns. The economic and social costs of airports are now very high, and place considerable constraints and responsibilities on airport planners. They can no longer presume to design airports in isolation, either from each other or from the urban and regional communities they serve. Nor can airport planners continue to expect that rapid growth and a generous public will afford them ample freedom as to what they build or do. We must now all learn to plan airports as integral parts of a larger system, and to face stringent economic and environmental realities.