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Vastly Distributed System

ATCSCC

CDM net TFM hub

TRACONsTRACONsTRACON(s)TowersTowersTowers

ARTCCARTCCARTCC(s)

TowersTowersAirports

Industry AOC(s)

Industry AOC(s)Industry

AOC(s)

GA

International

Military

Capacity/Demand Forecasts

? ? ?? ? ?

CDM History

Schedule Delay

Delay

Crews

FAs

Airframe

Passengers

Non-linear Response to Capacity Reduction

Reducing the airport capacity to 50%, generates over 65,000 minutes of delay at the airport and 139,000 minutes system wide.

0

50000

100000

150000

200000

250000

300000

100 96 92 88 83 80 75 72 67 63 58 55 50 47 42

Available Airport Capacity (Percentage)

Del

ay

Total System Delay

Total Airport Delay

Goals of CDM

• Transfer business decisions to users

• Use available capacity efficiently

• Improve predictability

• Ensure that the system is fair

The Pillars of CDM

Analytical Capability

Distributed Planning

Common Situational Awareness

• Measurement

• What-ifs

• Efficiency

• Equity

• Dynamic

• Decision Points

• Infrastructure

• Message Formats

• Display Tools

The most profound impact on the ability of Airline Operational Control Centers to interface with Traffic Flow Management has been the advent

of the Aircraft Situational Display.

What is a Ground Delay Program?

A ground delay program (GDP) is implemented at an airport when arrival demand exceeds capacity

0

5

10

15

20

25

1500 1600 1700 1800 1900 2000 2100 2200

Arrival Hour

Num

ber

of F

light

s

Demand is under capacity=> no problem

0

5

10

15

20

25

1500 1600 1700 1800 1900 2000 2100 2200

Arrival HourN

umbe

r of

Flig

hts

Capacity has dropped below demand=> problem for 4 hours

Ground Delay Program Goal

0

5

10

15

20

25

30

35

1500 1600 1700 1800 1900 2000 2100 2200

Arrival Hour

Nu

mb

er o

f F

lig

hts

Balance capacity and demand at impacted airport.

Delays taken on the ground, not enroute Reduces airborne congestion Delivers smooth and reduced arrival rate to the airport

11 Ts Determine a set of feasible arrival slot times {si}

isii AARss /11

where T1 = the start time of the program and

AARt = the arrival acceptance rate at time t

Assign flights to arrival slots

Fundamentals of a GDP: Adjust Demand to Meet Capacity

Each flight i has a reported arrival time ti

Let xi,j = 1 if flight i assigned to slot j, 0 otherwise

Solve to minimize total delay

Initial Approach to Assigning Arrival Slots: Ration by Reported Demand

ji

iji tsx j

,, )( Minimize

subject to

flight), onemost at assigned isslot (each

m1,...,jfor 1 , i

jix

slot), one toassigned isflight (each

n1,...,ifor 1 , j

jix

time).arrivalcurrent its before assigned isflight (no

if 0 itsx ji,j

Original schedule

Arrival slots

• External circumstances can change an airlines schedule

Problems with Rationing byReported Demand

Arrival slots

Original schedule

Modified schedule• External circumstances

can change an airlines schedule

• Flights are cancelled

• Flights are delayed

• Reporting these changes can help competitors more than the reporting airline

Problems with Rationing byReported Demand

Arrival slots

delay

cancellation

Original System Could Not Respond to Airline Actions

• Airlines operate flights in banks to facilitate passenger connections

• Ground Delay Programs disrupt banks

Arrival slots

Original schedule

• Airlines operate flights in banks to facilitate passenger connections

• Ground Delay Programs disrupt banks

• Airlines respond by delaying flights to preserve banks => demand and capacity again out of line

• ATM control only dictates earliest time a flight can arrive

Arrival slots

Original schedule


• Flights are assigned to arrival slots based on known demand

• Unexpected flights appear (military, general aviation, others unscheduled)

• Demand again exceeds capacity leading to airborne holding, diversions and ground stops

Arrival slots

Original demand


Revised demand

CDM Approach to the Problem• Recognize that this is best addressed as a distributed

optimization problem– FAA allocates arrival slots to airlines

• equitably and efficiently

– airlines assign flights to their allocated arrival slots

• optimize their own cost function

– iterative approach

• continual re-evaluation of demand vs. capacity and adjustments as necessary

• Allocation of slots must be equitable, and reward rather than punish data exchange

Assigns flights to slots and adjusts demand based on economic objectives

FAA Airlines

Assigns slots based on capacity

Equitable Allocation of Arrival Slots:Ration by Schedule

Original schedule

Arrival slots

• Arrival slots are distributed according to published schedule rather than reported demand


Original schedule

Arrival slots


• When flights are cancelled or delayed, airlines retain rights to those slots

Cancelled slot still owned by blue airline

cancellation

delay

Modified schedule



• Airlines can assign flights to slots in whatever way best suits their business needs

• An optimal solution is found that is accepted and understood


cancellation

delay


Modified schedule

Arrival slots

• Often airlines are unable to use their allocated slots

• Without FAA action, resources would be wasted

• Compression, moving flights up to fill vacant slots, benefits everyone

Maximizing Available Resources:Compression

Modified schedule

Arrival slots





Modified schedule

Arrival slots

Original demand

Original program

Program Revisions Adjust to Changing Conditions

• Original program based on known demand



• When demand changes existing program becomes invalid

Expected arrivals after

revision

Revised demand


Original schedule


revision

Revised demand



• Revision of the program reassigns arrival slots to updated demand

• Balance between demand and capacity is restored

• Delays are taken on the ground rather than in the air. This is cheaper for the airlines and safer for the flying public.

Pre-CDM GDP Process

• No opportunity for the airlines to solve the problem and avoid the GDP

• No ability for the FAA to respond to changing conditions with revisions or compressions

• No smooth transition out of the GDP

FAA/Airline Evaluation Demand Vs.

Capacity

GDP ModelingSend GDP Advisory

Issue GDP

(Ration by reported demand)

Airline Response(Substitutions & Cancellations)

Program expires or is cancelled

Current CDM GDP Process


Capacity

GDP ModelingSend Proposed GDP

Advisory

Airline Response(cancellations)

Is GDP still required?

Issue GDP Airline Response(Substitutions & Cancellations)

CompressionGDP Revision/Extension

Yes

End

No

Exit loop when program expires or is cancelled.

(Ration by schedule)

Collaborative Decision Making

Capacity/Demand Management

Passengers

60

116

93

87

87

Total 443

P-DELAY = #PSGR X min DLYD

P-Delay min = 26580

P-Delay min =3600

Original P-Delay is

738% greater than revised

Passengers

0 CNX

176 (60 late)

93

87

87

Some Perceived Problems

• Airlines are over-scheduling airports

• Airlines are withholding delay and cancellation information from the passengers.

Over-scheduling?

• PHX schedules at VFR conditions for certain time frames.– 344 days without a GDP

from June 2000 to present.

– GDP delays range from 60 to 238 minutes

– 6,192 more scheduled operations, than if scheduled to IFR conditions.

Over-scheduling?

• BOS schedules at VFR conditions for certain time frames.

– 250 days without a GDP from June 2000 to present.



TFM Dependencies

Although, the capacity at an airport is reduced and ATC delay has been applied, users may cancel and delay flights as well as notify the FAA of earliest feasible departure times of flights.

FAA Actions

Cancellations

Airline Delays beyond ATC delay

Earliest Departure/Arrival Time updates

Airline Actions

Issue ATC delay

Generate Demand

Collaboration is Essential to Maximizing Resources

• When Capacity is Reduced, Airlines Adjust their Schedules by Delaying, Canceling and Substituting Flights.

• These Schedule Changes are Communicated to the FAA through the CDM Network.

• The FAA Uses this Information to Maximize Capacity Usage through Revisions, Compressions, and other Delay Reducing Procedures.

• To Achieve this Efficiency, Departure Times Must Remain Flexible.

• Delays that are Communicated to the Passengers are difficult to Reduce.

Airline and FAA Actions can Reduce Delays

Future Steps for CDM

• Improve Demand-Capacity predictions– Demand Uncertainty

– Capacity Uncertainty• Improve dynamic resource allocation

– User system dependencies

– Passenger dependencies• Integrated System Solutions

– Local versus National Traffic Management Initiatives

– Strategic versus Tactical Traffic Management Initiatives

CDM Approach to the Problem• Recognize that this is best addressed as a distributed

optimization problem– FAA allocates arrival slots to airlines

• equitably and efficiently

– airlines assign flights to their allocated arrival slots

• optimize their own cost function

– iterative approach

• continual re-evaluation of demand vs. capacity and adjustments as necessary

• Allocation of slots must be equitable, and reward rather than punish data exchange

Assigns flights to slots and adjusts demand based on economic objectives

FAA Airlines

Assigns slots based on capacity


Original schedule

Arrival slots



Original schedule

Arrival slots




cancellation

delay

Modified schedule



• Airlines can assign flights to slots in whatever way best suits their business needs

• An optimal solution is found that is accepted and understood


cancellation

delay


Modified schedule

Arrival slots





Modified schedule

Arrival slots





Modified schedule

Arrival slots

Original demand

Original program







revision

Revised demand


Original schedule


revision

Revised demand



• Revision of the program reassigns arrival slots to updated demand

• Balance between demand and capacity is restored

• Delays are taken on the ground rather than in the air. This is cheaper for the airlines and safer for the flying public.

Pre-CDM GDP Process

• No opportunity for the airlines to solve the problem and avoid the GDP

• No ability for the FAA to respond to changing conditions with revisions or compressions

• No smooth transition out of the GDP


Capacity

GDP ModelingSend GDP Advisory

Issue GDP

(Ration by reported demand)

Airline Response(Substitutions & Cancellations)

Program expires or is cancelled

Current CDM GDP Process


Capacity

GDP ModelingSend Proposed GDP

Advisory

Airline Response(cancellations)

Is GDP still required?

Issue GDP Airline Response(Substitutions & Cancellations)

CompressionGDP Revision/Extension

Yes

End

No

Exit loop when program expires or is cancelled.

(Ration by schedule)

Collaborative Decision Making

Capacity/Demand Management

Passengers

60

116

93

87

87

Total 443

P-DELAY = #PSGR X min DLYD

P-Delay min = 26580

P-Delay min =3600

Original P-Delay is

738% greater than revised

Passengers

0 CNX

176 (60 late)

93

87

87

Some Perceived Problems

• Airlines are over-scheduling airports

• Airlines are withholding delay and cancellation information from the passengers.

Over-scheduling?

• PHX schedules at VFR conditions for certain time frames.– 344 days without a GDP

from June 2000 to present.



Over-scheduling?

• BOS schedules at VFR conditions for certain time frames.

– 250 days without a GDP from June 2000 to present.



TFM Dependencies

Although, the capacity at an airport is reduced and ATC delay has been applied, users may cancel and delay flights as well as notify the FAA of earliest feasible departure times of flights.

FAA Actions

Cancellations

Airline Delays beyond ATC delay

Earliest Departure/Arrival Time updates

Airline Actions

Issue ATC delay

Generate Demand

Collaboration is Essential to Maximizing Resources

• When Capacity is Reduced, Airlines Adjust their Schedules by Delaying, Canceling and Substituting Flights.

• These Schedule Changes are Communicated to the FAA through the CDM Network.

• The FAA Uses this Information to Maximize Capacity Usage through Revisions, Compressions, and other Delay Reducing Procedures.

• To Achieve this Efficiency, Departure Times Must Remain Flexible.

• Delays that are Communicated to the Passengers are difficult to Reduce.

Airline and FAA Actions can Reduce Delays

Future Steps for CDM

• Improve Demand-Capacity predictions– Demand Uncertainty

– Capacity Uncertainty• Improve dynamic resource allocation

– User system dependencies

– Passenger dependencies• Integrated System Solutions

– Local versus National Traffic Management Initiatives

– Strategic versus Tactical Traffic Management Initiatives

Documents

Www.metsci.com/cdm. Vastly Distributed System ATCSCC CDM net TFM hub TRACONs TRACON(s) Towers ARTCC ARTCC(s) Towers Airports Industry AOC(s) GA International