1. Airborne Flights with ETA before the GDP Start Time CDM A&D Meeting 5 June 2001

2. 2 Background Action Item from the April 18, 2001 CDM A&D Meeting. Reference the QA Data Quality Presentation. Airborne flights are included into the GDP by IGTA – taxi, but some of their ETA are before the Start Time. Can lead to under-delivery in the first GDP hour. Translates into high accumulated delay for Non-Exempt flights.

3. 3 Impact Study Look at the ETA at model time versus ARTA. LGA ORD Two alternatives Exclude the airborne flights with ETA before GDP start time. Create open slots for these airborne flights to use in compression. Further approximation on the impact if these fixes were in place from 01/01/2001 to 04/30/2001. Summary of the Pros and Cons

4. 4 ETA versus ARTA Occurrences of airborne flights with ETA before the Start Time of the GDP and the ARTA of those flights from January 01, 2001 to April 30, 2001. Minutes from Start Time LGAORD 18 30 12 115 6550

5. 5 Alternative 1: Exclude airborne flights with ETA before GDP Start Time PROS –Allows airborne and exempt flights with ETA during the program better slot allocation in the first hour. –Reduces delay to all non-exempt flights –Best fills the capacity of the first GDP hour. CONS –May lead to over-delivery –Does not issue the slots by Scheduled Times of Arrival, relies on modeled ETA.

6. 6 ORD 04/08/2001 1448 ADL Total delay reduced from 27,495 to 25,559 minutes The first GDP hour is now filled after the model. Current With airborne exclusions

7. 7 Alternative 2: Open Slots for Compression PROS –Slots are still owned by the initial carriers. –May not lead to over-delivery. CONS –May not fill the first hour’s capacity, due to rules of compression. –May not reduce delay in some cases. –Slots that were once not open are compressible. Non-Exempt flight COMPRESSION Open Slot of airborne flight ETA of included airborne flight Start time

8. 8 Impact if fixes were in place from 01/01/01 to 04/30/01

9. 9 Summary Exclusion Open slot Pros -Best fills capacity -Carrier keeps slot -Reduces delay -Over-delivery a minor threat -May reduce delay Cons -May over-deliver -May not fill capacity -Relies on modeled ETA data-Relies on modeled ETA data -Schedule is not used for active -Does not reduce delay as much as flights exclusion method