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For ecasting for Airport Planning 169

competition from mortgages, savings, and luxury goods. Foreign
travel by U.S. citizens will be adversely affected by the decline in the
exchange value of the dollar. Furthermore, this factor will encourage
foreign nationals to travel to the United States [12, 13, 14].
Conferences related to aviation forecasting methodologies [10]
concluded that financial concerns and forces concerns are forcing the
aviation industry to place more emphasis on short-term forecasting
methods. This is not only the case with the airlines but airports are
also shortening their planning horizons. Throughout the aviation
industry there is a shift to simpler forecasting techniques requiring
fewer variables and less detailed data. A wider use is being made of
forecasting techniques which depend less on mathematical modeling
and more on an analysis of different scenarios, judgment, and market
segmentation. Scenarios are used to test basic assumptions and to
explore alternatives. Although judgment has always played a signifi-
cant role in demand forecasting it is becoming more important as a
subjective test of the reality associated with forecasting outcomes.
There is a growing recognition that airline management strategies are
important forces shaping the future of aviation development.
To adequately cope with the uncertainties associated with the tra-
ditional air transportation forecasting process and to react in a timely
manner to inaccuracies found in estimates, the planning process is
emerging into a phase-oriented, continuing process. For example, the
FAA prepares annual forecasts of aviation activity on a national and
terminal area basis which extend several years into the future [8, 9,
18]. Due to the high costs associated with the traditional planning
process and the implementation of physical design changes, and the
apparent inability to forecast with any degree of certainty, it is essen-
tial that planning techniques be developed which can respond to
changes in the demand parameters prior to the investment decision.
Perhaps the key to such a process is the recognition of the interaction
of demand to supply parameters. The knowledge of the sensitivity of
a physical facility component to a variation in demand can lead to
more informed decisions and an understanding of the flexibility in
facility design. A continued monitoring of the need for physical facil-
ities in light of changing demand requirements provides a sound
basis for the investment decision. Recognition of the uncertainties in
the demand forecasting process can prevent a wasteful commitment
of valuable resources. Explicit treatment of the variability of demand
projections and facility modification recommendations though the
use of sensitivity and tradeoff analyses is warranted.

References
1. Airport Aviation Activity Forecasting—A Synthesis of Airport Practice, ACRP
Synthesis 2, Airport Cooperative Research Program, Transportation Research
Board, Washington, D.C., 2007.