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Conclusions and Recommendations for Further Research P a r t I V
109 14.1 Conclusions This report finds that (1) differences between assumed and actual events significantly diminish the accuracy of airport activity forecasts developed with traditional techniques and, (2) the principal forecasting challenge is dealing with the risks and uncertainties that drive a wedge between assumed and actual outcomes. While it can be instructive to explore singly the effect on airport activity forecasts of assumptions made about this or that particular outcome, in the real world literally every important outcome will differ from the one initially assumed. Another approach is to develop forecasts under worst-case and best-case conditions. However, this approach has little practical value because the likelihood of everything deviating from expectations in the same direction is just as remote as everything turning out exactly as assumed. To be useful as a guide to airport planning and decision making, forecasts must take into consideration the cumula- tive and simultaneous effect of risk and uncertainty in every factor germane to development of airport activity forecasts. A unified systems analysis framework has been developed here that enables airport activity forecasters to identify risk factors, understand the extent to which each risk factor introduces uncertainty into activity forecasts, and ascertain how the risks and uncertainties are likely to interact so as to examine realistically their combined implications for air traffic going forward. Although a unified systems analysis methodology has been developed, it need not and should not be viewed as a one-size- fits-all approach for all airports and all projects. The guide- book develops the systematic protocols airport planners can employ in order to apply the systems analysis methodology at different levels of quantitative and qualitative detail. This ranges from almost no quantitative analysis at all to highly sophisticated statistical and simulation-based methods. In all cases, however, we find that there is a very important role for management and stakeholder discussion and consensus, and elicitation methods are presented as part of the systems analysis methodology. Airport activity forecasts, when developed within the sys- tems analysis methodology presented here, can inform the airport planning process in ways that lead to better invest- ment decisions in relation to facility scale, design, and sched- uling. The understanding of risk and uncertainty brings with it the ability to make airport master plans and com- ponent project plans a great deal more robust in relation to risk, uncertainty, and, in general, difficult-to-anticipate outcomes. Airport design and engineering sciences have produced mechanisms that enable staged development and other means of maximizing value by averting premature or later-than-optimal expansion. By significantly expanding airport managementâs understanding of the risk to the timing of capacity requirements, the unified systems analysis devel- oped in this guidebook enables the most effective use of new design and engineering advances. 14.2 Recommendations for Further Research In applying the methodology presented in this report, air- port forecasting and planning will be more robust to uncer- tainty and risk. The report does, however, identify the need for additional research and methodological development in relation to two factors that continue to threaten the accuracy and productive role of airport activity forecasts, namely: ⢠Rare, high-impact events, and ⢠Political risk. Rare, high-impact events are events of significant conse- quence for which there is a sparse historical record from which to develop statistically predictive patterns (see Section 4.3). Such events nonetheless pose material challenges for air- port activity forecasting and planning. One is identifying C h a p t e r 1 4 Conclusions and Recommendations for Further Research
110 methods can be integrated with the methodology developed in this guidebook to enhance the way airports accommodate the reality of rare, high-impact events in the planning process. The risks of political factors altering the appropriate design, timing, or financial arrangements for airport development, while less amenable to quantitative treatment than economic, demographic, and other statistically measurable variables, can be no less significant in their implications for airport plans. Runway development, for example, is often a source of significant political risk, and systematic approaches to explicitly dealing with such risk would be productive. In general, infrastructure is susceptible to political factors, and the aviation research in the literature has examined these factors specifically in relation to runway and air traffic control development (for example, see Bodde and Lewis, 1984). Further research is required to more fully and formally integrate political risk into the systems analysis methodology. and anticipating them: Will a volcano erupt and shut down the airport and airway system? The second is anticipating their impact on demand and formulating an appropriate planning response: some rare events have a high but short- lived impact on demand and thus do not call for a long-term planning response. Other kinds of rare events create the need for a mitigation or risk management plan. Further research is required in relation to the identification of rare events whose impact can justify a strategic response and shift the pattern or growth of airport activity on a long-term basis. The latter includes sudden technological eventsâfor example, the abrupt arrival of microwave landing system tech- nology in the 1980s with the promise of major runway capacity improvements and the equally abrupt arrival of satellite-based avionics that doomed microwave technology to early obso- lescence. To mitigate such risks, the research should explore airport-related applications of remedies such as protective strategy and dialectical inquiry (see Section 4.3) and how such
