October 31, 2001 1

October 31, 2001Metron Aviation, Inc.

Dan Rosman

Assessing System Impacts: Miles-in-Trail and Ground Delays

October 31, 2001 2

En-Route TFM Issues

• What Problems are we Trying to Solve?– Sector Congestion

– System Predictability and Results of Prediction Errors

– Flight Route Coordination

– Equitable Allocation of Resources

– Efficient Use of Resources

October 31, 2001 3

Ground Delays and MIT Restrictions

• Ground delay programs and ground stops prevent airborne delays but may result in underutilization of arrival capacity because of changing demand

• Miles-in-Trail provides an airborne reservoir which may result in greater airborne holding costs and increase air traffic control workload

• Need some combination of strategic initiatives that is market driven and optimizes trade off between airborne holding and ground delay costs

October 31, 2001 4

Ground Delays and MIT Restrictions

• There are currently 203 daily historically validated miles-in-trail restrictions

• On average, 186 dynamic miles-in-trail restrictions occur each day– 13.5 flights impacted by each restriction

– 8.5 flights affected for each hour that MIT restriction was in place

• In 2000, there were 1083 ground delay programs averaging 6.5 hours in length per program

October 31, 2001 5

Approach

• NAS-Wide System Impact Assessment Tools are Needed– What impact does an en-route constraint have on the airport operation

(arrival, departure, surface)?

– What about surface constraints on the en-route operation?

– These impacts are significant and affect system performance

– TFM constraints impact equity

• Collaborative En-Route Flow Management Tool (C-Flow)– Prototype System Impact Assessment Tool is Currently Being

Developed

– Validated through quantitative analysis

– Validated through human-in-the-loop simulation

October 31, 2001 6

C-Flow Concept

• C-Flow Provides Common Visualization of Flow Restrictions and Impacts

• Resultant airport flows• Sector counts• Airborne delay in sectors

• C-Flow Dynamically Updates Impact Predictions

• ATC Specialists Can Evaluate the Need for Restrictions

• Can a restrictions be dropped?• Are new restrictions needed?

• New Restrictions can be Planned by Evaluating the Predicted Impact on Flow Rates, Delays and Equity

30

20ORDGDP

Upstream Effects of Traffic Management Restrictions

20

Delay BuildupFlow Shut-off

Airport GridlockGround Stop

ZOB48

Cumulative Effects of Traffic Management Restrictions

Even Arrival Flow with GDP

20

20Slots Lost with MITs

C-Flow GUI Display

October 31, 2001 10

System Impact Analysis

• Using C-Flow, Analyzed LAX Traffic Management Program on May 1, 2001– Ground delay program initiated after host computer problems at

ZLA

– ARTCCs adjacent to ZLA also added miles-in-trail restrictions

– ZLA also assigned release times for internal departures

– Significant delays result• But some delay was unnecessary

• Excess unused capacity at LAX

October 31, 2001 11

System Impact Analysis

• C-Flow Modeled Four Major TFM Elements:

– Ground delay program

– Miles-in-trail restrictions

– Internal departure release times

– Sequencing and separation of flights

• The Results Showed Good Correlation with Actual Operations

– An operational C-Flow could help avoid the under-delivery problem

October 31, 2001 12

Simulation of LAX Event 5/1/2001Program 1630Z to 2359Z, LAX at 60/64 Arrivals per Hour

Bars show arrival sector loading and anticipated delay to be absorbed under simulated flow. Note the significant delay indicated (ZAB92).

MIT parameters based on actual restrictions applied

October 31, 2001 13

Simulation of LAX Event 5/1/2001

Time1400 10 10

2 213 1211 35 11 35

1500 15 1313 715 1515 58 13 48

1600 15 1315 815 1113 58 8 40

1700 17 1015 915 915 62 13 41

Arrivals - MIT 60Arrivals - URS 60

October 31, 2001 14

Current C-Flow Development

• Near Real-Time Infrastructure Under Development– POET database

• Allow trajectory predictions to be stored in database

• Compute sector entry and exit times for predictions

• Produce sector load metrics from predictions

• Trajectory Prediction (non-developmental item)– Integrate latest trajectory prediction software

– Collect and archive RUC2 wind data

• Graphical User Interface (developed as variant of GCDR)

October 31, 2001 15

Future Development Phases

• Phase 1 – Predict and display traffic flows that result from miles-in-trail

restrictions obtained from the National Log Program• In downstream sectors and to airports

• Assist ATC specialists to determine if MIT restrictions are necessary

• Phase 2– Over/Under constrained decision support due to MIT and possibly

GDP restrictions• Provide automated alert if MIT restrictions

– are not enough to avoid excess demand downstream

– are more than necessary to avoid excess demand downstream

October 31, 2001 16

Development Phases (cont.)

• Final Product: System Impact Assessment Tool– Assist ATC specialists in selecting between strategies:

• Re-routes

• Ground stops

• GDPs

• Sector GDPs

• Miles-in-trail

• Other initiatives

– Predict and display flow and equity of each strategy or a combination of strategies

October 31, 2001 17

Evaluation Phases

• Shadow Operations and Evaluation– Analytical evaluations to assess sector demand prediction accuracy– Demonstrations to users to obtain subject matter expert feedback

• War-Game– Human-in-the-loop simulation of ATCSCC, TMU and AOC– Simulated evaluation of use of C-Flow for

• What-If evaluations of traffic management strategies• Communication of predicted congestion and delays to airlines

• Goal of War-Game– Validation of tool capabilities– Identification of missing capabilities– Validation/Improvement of user interface– Development of procedures for use of tool– Identification of methods for collaborative decision making

October 31, 2001 18

Summary

• Air traffic community has a clear need for system impact assessment tools and analysis

• C-Flow is currently being developed to meet that need- Ground stop and ground delay models

- MIT model

• Current prototype needs to be expanded to incorporate other traffic management initiatives

• End product will allow user to evaluate tradeoffs between initiatives and arrive at efficient and fair allocation of resources that solve en-route congestion problems