1. Dr. Richard de Neufville
Massive Uncertainty
Dr. Richard de Neufville
Professor of Systems Engineering and
Civil and Environmental Engineering
Massachusetts Institute of Technology
Airport Systems Planning & Design / RdN

2. Airport Systems Planning & Design / RdN
Massive Uncertainty
Objective: To present realistic context of forecasting exercise
Topics
Evidence
Consequences
Airport Systems Planning & Design / RdN

3. Airport Systems Planning & Design / RdN
Causes of Uncertainty
Underlying variability of phenomenon
Difficulties in measurement or estimation
Unforeseen or “unpredictable” circumstances
Limits to valid measurement
for example: behavioral patterns
Airport Systems Planning & Design / RdN

4. Airport Systems Planning & Design / RdN
Evidence
1. Simple Physical Systems
2. Overall Traffic
3. Local Traffic (Worse)
4. Other Operations
Airport Systems Planning & Design / RdN

5. Ratio of Real Costs to Estimated Costs for Airport Projects
Costs expressed in constant dollars
Median ~= 1.25
Percent of Occurrences
Real/Estimated Cost Ratio
Airport Systems Planning & Design / RdN

6. Cost Growth for Various Projects
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Ratio of Actual to Estimated Cost
DOD60 HWAY WATER BLDNG DOD50 ADHOC MAJOR ENRGY NASA NASA AVG St.Dev.
CONST SAT m g
Airport Systems Planning & Design / RdN

7. NASA Projects Cost Growth
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Ratio of Actual to Estimated Cost
HST GLL UARS GRO COBE MGL MOBS LSAT EUVE ERBE AVG St.Dev.
Airport Systems Planning & Design / RdN

8. Airport Systems Planning & Design / RdN
Forecasting Errors
Nature of
Traffic
Type of
Traffic
Percent Error which is Exceeded Half
the Time after Each year
One
Year
Two
Years
Three
Years
Four
Years
Five
Years
Six
Years
International
US Domestic
Passengers
Pax-Miles
Average
8.0
7.2
7.6
2.9
10.9
6.2
6.0
6.1
14.0
13.8
13.9
11.2
10.6
10.9
14.0
15.7
14.9
14.1
14.5
14.3
15.1
16.7
15.9
18.3
15.8
19.5
17.6
20.4
21.8
21.1
Average Errors in the Forecasts of Air Traffic of the U.S. Federal Aviation Administration,
Airport Systems Planning & Design / RdN

9. FAA Forecasts Compared with Actual Data (% Difference)
Review of the FAA 1982 National Airspace System Plan
Airport Systems Planning & Design / RdN

10. Forecast vs. Actual International Pax in Japan
Airport Systems Planning & Design / RdN

11. Forecast vs. Actual International Pax to Japan
Airport Systems Planning & Design / RdN

12. Forecast vs Actual International Pax in Sydney
Airport Systems Planning & Design / RdN

13. ACTIVE GENERAL AVIATION AIRCRAFT
1980 FORECAST
Airport Systems Planning & Design / RdN

14. ACTIVE GENERAL AVIATION AIRCRAFT
1985 FORECAST
Airport Systems Planning & Design / RdN

15. 1990 FORECAST ACTIVE GENERAL AVIATION AIRCRAFT
Airport Systems Planning & Design / RdN

16. 1998 FORECAST ACTIVE GENERAL AVIATION AIRCRAFT
Airport Systems Planning & Design / RdN

17. Summary and Recommendations
Forecast Errors have been large
Likely to continue
Recommendations:
Expensive Forecasting is cost-ineffective
Use general trends
...With large ranges
Flexible Approach to Planning!!!
Airport Systems Planning & Design / RdN