The benchmarks in this report are a relatively simple expression of a complex quantity, airport capacity. They serve primarily as a reference point on the state of the airport system at a specific time. They can be updated in the future to mark progress. They can also be used to identify and compare specific types of airports, for instance to determine which airports are most severely affected by adverse weather or to compare the prospects for airports that plan to build new runways to those that do not. The benchmarks also provide a starting point for public policy discussions, because they give a succinct report on the current and future state of major airport capacity.
Benchmarks are useful data that help frame discussions.
However, they are not a substitute for the more detailed analysis that should precede major investment and policy decisions. In this sense they might be compared to a vital sign of human health, such as blood pressure. That simple indicator might be the starting point for a diagnosis, but more information would be wanted before recommending surgery. Similarly, capacity benchmarks help identify problem areas but are not, in themselves, an adequate basis for selecting remedies. This issue is apparent in the case of Atlanta Hartsfield International Airport.