Airborne Flights with ETA before the GDP Start Time

CDM A&D Meeting

5 June 2001

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

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

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 TimeLGA ORD

0

1

2

3

4

5

6

7

8

9

10

5 minute time bins

freq

uenc

y

0

5

10

15

20

25

30

35

40

45

5 minute time bins

freq

uenc

y

ARTA

ETA at model time

18

30

12

115

65 50

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

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

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

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

Exclusion alternative Open Slot alternative

LGAprograms 49 49

usable slots before drift 30 slots 6 slotsusable slots after drift 18 slots 6slots

GDP capacity gained before drift .88 hour .18 hourGDP capacity gained after drift .53 hour .18 hour

potential delay reduction 31,135 minutes 6,227 minutesminimum appox. delay reduction 18,681 minutes 6,227 minutes

potential cost reduction $778,375 $155,675minimum appox. cost reduction $467,025 $155,675

ORDprograms 40 40

usable slots before drift 115 slots 64 slotsusable slots after drift 65 slots 64 slots

GDP capacity gained before drift 1.51 hours .84 hourGDP capacity gained after drift .86 hours .84 hour

potential delay reduction 106,778 minutes 59,425 minutesminimum appox. delay reduction 60,353 minutes 59,425 minutes

potential cost reduction $2,669,450 $1,485,625minimum appox. cost reduction $1,508,825 $1,485,625

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