1. Distance-Based GDPs Guillermo Lulli, Mike Ball (U of MD) Bob Hoffman (Metron)

2. Distance-Based GDP • Replaces Tier Approach • GDP options are defined by drawing a circle around the airport and including all enclosed airports: • All flights whose origin is within circle and whose arrival time is within GDP time period are included. • Alternative programs obtained by increasing radius of circle.

3. Distance-based GDP vs Current Approach • Flexibility: a wider range of possible solutions is available. • Dominance: for each tier-based initiative, there is a corresponding distance-based initiative. • Simplicity: the range of programs can be varied in a simple well-defined manner.

4. Airports considered • Atl 2 Nov 99 ft 16.54 19.00 - 23.00 aar 76 • Bos 2 Feb 00 ft 17.02 19.00 - 00.59 aar 40 • Dfw 10 Oct 98 ft 12.48 14.00 - 19.59 aar 64 • Dtw 6 Apr 00 ft 15.14 16.00 - 21.59 aar 36 • Ewr 27 Feb 00 ft 15.19 18.00 - 23.59 aar 36 (3)/40 (3) • Iah 24 Feb 00 ft 17.02 19.00 - 00.59 aar 40 • Ord 3 Feb 00 ft 16.51 18.00 - 01.59 aar 76 (2)/80 (6) • Phl 13 Aug 99 ft 18.04 20.00 - 01.59 aar 40 • Sfo 18 Aug 99 ft 13.32 16.00 - 21.59 aar 30 (3)/40 (3) • Stl 19 Mar 99 ft 12.58 16.00 - 21.59 aar 32

5. Statistics used in our analysis: • Total delay • Airborne Holding delay • Unrecoverable delay • Affected flights • Max delay • Average delay • Unnecessary delay: part of delay that is not necessary to meet the increased AAR, if the program is cancelled • if OTD<CT<ETA min{ CT- OTD, ETD-OTD, ETA-CT}, • else 0.

6. Bos 2 Feb 99Distances vs Tiers Air Hold Unrec Avg Aff flights Max

7. Bos 2 Feb 99 Average delay vs Unrec. delay Unrec Avg.

8. Trading Off Avg Delay and Unrecov Delay • Choose weights for each and consider: wgt1 ave-delay + wgt2 unr-delay • Find distance that minimizes this weighted sum. • Nominal values for this analysis: wgt1 = 50 wgt2 = 1

9. Bos 2 Feb 99Weighted trade-off between Avg and Unrec. delay Unrec Trade-off Avg

10. Bos 2 Feb 99Varying Tradeoff Weights 98 1

11. Bos 2 Feb 99Avoiding Inefficient Solutions Unrec Efficient solutions

12. Efficient Initiatives: numerical example • By varying distances inefficient initiatives can be avoided (Bos 2 Feb 99)

13. Bos 2 Feb 99 Consideration of Fairness: Delay Variability Unrec Delay Var Avg.

14. Stl 19 Mar 99Distances vs Tiers Air Hold Delay 1th 2nd Max Avg Aff flight Unrec

15. Stl 19 Mar 99 Average delay vs Unrec. delay Avg Unrec

16. Stl 19 Mar 99Weighted trade-off, Avg and Unrec. delay Trade-off Unrec Avg 2nd Tier

17. Stl 19 Mar 99 Different Weighted trade-off 68 20

18. Stl 19 Mar 99 Avg delay vs Unrec. Delay & Delay Variability Unrec Delay Var Avg

19. Sfo 18 Aug 99Distances vs 6 & 10 west 6W 10W Max Air Hold Unrec Avg Aff flights

20. Sfo 18 Aug 99Weighted trade-off, Avg and Unrec. delay Trade-off Avg Unrec 6W 10W

21. Unrecoverable Delay ==>Unnecessary Delay unrecoverable delay = ground delay incurred by start time of program: if program canceled at start then all of this delay is unnecessary but none is recoverable What if program is canceled earlier or later than start time of program?? unnecessary delay = ground delays applied to flights that push their CTAs past the program cancellation time expected unnecessary delay = expected value of unnecessary delay computed using distribution of possible cancellation time.

22. Sfo 18 Aug 99Unnecessary delay (early cancellation time)

23. Sfo 18 Aug 99Unnecessary delay (middle cancellation time)

24. Sfo 18 Aug 99Unnecessary delay (late cancellation time)

25. Sfo 18 Aug 99Unrecoverable vs expected Unnecessary delay Unrec Unnec

26. Sfo 18 Aug 99Unrec., Unnec. delay and weighted trade-off Unrec Unnec Avg weighted trade-off local minimum

27. Conclusions: • Distance-based GDPs provider greater flexibility but are easy to understand and manipulate. • Flexible user interface could be developed to display and analyze options.