ABSTRACT
The current downturn in world aviation markets has eased pressures on capacity at a number of major airports but in many cases capacity shortages continue to exist. There are a number of reasons for this. The overwhelming majority of airports are still publicly controlled utilities subject to political whims and tight budgets, but even where such constraints apply less (as in the UK) expansion has been hampered by environmental limitations and other planning controls. Building new runways or lengthening existing ones is not always an easy task.
