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George Mason University March 18, 2004 Harvard University

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1 George Mason University March 18, 2004 Harvard University
Air Transportation is a Complex Adaptive System: Not an Air Traffic Control Automation Problem Dr. George L. Donohue George Mason University March 18, 2004 Harvard University © George Donohue 2004

2 Outline How did We Get Here? Why Should We Care? Capacity - Delay
Capacity – Delay – Safety System Network Effects Observations and Recommendations

3 How did We Get Here? 1903 Wright Bros. produced a Heavier than Air Flying System: AGE OF INVENTION Airfoils, L/W Structure, Controls, L/W Propulsion WW II ( +50 Yrs) System is Upgraded: AGE OF ALL WEATHER COMMERCIAL FLIGHT Radar, Jet Aircraft, Radio Navigation and Communication 2003 ( +100 Yrs.) System Needs Upgrading Again: AGE OF RELIABLE INTERNATIONAL TRANSPORTATION NETWORK Predictable under all Weather Conditions Maximum Airport Capacity Utilization Near Optimal Network Load Balancing Predicable Safety Operating Margins

4 Barriers to the Third Age Vision
The Technical Community has been Aware of the Transition Problem for Over 20 Years! Increasing Delays, Flight Cancellations Increasing Runway Incursions, ATC Op Errors and TCAS RA’s The Technical Elements that will enable the Development of an Affordable, Reliable, and Predictable Mode of International Transportation Already Exist! TCAS II Deployed Worldwide No System Credit FMS with ±30 Sec. RTA ? No System Credit GPS Navigation and Surveillance (ADS-B) No System Credit Digital Communication Data Links NOT DEPLOYED TMA, pFAST, aFAST, URET No System Credit The Barriers to Growth are Regulatory and Institutional!

5 Increasing Delay is a Frog in the Boiling Water Problem
Deregulation Source: USDOT BTS NTS 2000; USDOT BTS update April, 2002; DOC BEA 2002 (*real GDP using 1996 chained dollars

6 Air Transportation’s Contribution to GDP

7 Civil Transport Share of Aerospace Industry

8 Capacity and Delay System Capacity is Primarily Limited by Network Runway Availability ATC Workload is an important Secondary Limitation Runway Maximum Capacity is a function of Aircraft Landing Speed and Runway Occupancy Time (ROT) Delay is a Non-Linear function of Demand to Maximum Capacity Ratio Stochastic FCFS System Queuing Theory Applies Major Hub Airports are Over-Scheduled Transportation Network Is NOT LOAD BALANCED Market Mechanisms Could Achieve this Goal

9 Network Operational Capacity is a Limited Commodity
CMAX = 2 C AR MAX S i (XG)i Ri {Airports} –K AK(t) {Airspace Management Intervention} S = f ( Safety, ATC , Wake Vortex, etc.) ~ 0.6 to 0.8 AK(t) = (A/CREQUEST – A/CACCEPT) ~ [ 0 to >1,000] AK(t) = f ( GDP:Weather, Sector Workload Constraints ) C AR MAX ~ 40 Arrivals/Hour (set by Runway Occupancy Time) Ri = Number of Runways at ith Airport XGi = Airport Configuration Factor at ith Airport i = 1 to N, where N is approximately 60 Airports K = 1 to M, where M is typically much less than 100 Sectors

10 ATS Delays Grow Exponentially with Increasing Capacity Fraction

11 Aircraft Arrival Rate: Distance-Time Relationship
Spacing (sec) 60 ROT? 72 90 WV? 120 180

12 NY LaGuardia: A non-Hub Maximum Capacity Airport
1 Arrival Runway 1 Departure Runway 45 Arrivals/Hr (Max) 80 Seconds Between Arrivals 11.3 minute Average Delay 77 Delays/1000 Operations 40 min./Delay Airport is overscheduled almost entire day (peak one op/min)

13 New York LaGuardia Airport Arrival- Departure Spacing VMC
Data provides inputs to airspace models Significant observations of operations outside of calculated capacity, possible hazard 45 Arr./Hr/RW @ 80 sec separation DoT/FAA

14 LGA Arrival - Departure IMC

15 Capacity-Delay-Safety
ATM System Safety and Capacity are Non-Linearly Related Wake Vortex Separation sets the Current System Capacity Limit in Instrument Meteorological Conditions Safety Limitation ICAO System Safety Goal is 10-9 / Operation Small number Statistics leads us to use Accident Precursors as Safety Indicators Safety Analysis must be Analytical

16 Time Separation Is an Important Determinant of the SAFETY Limitation
35+ Arrivals/RW/Hr ROT Probability A/C Inter-arrival Time Time (seconds)

17 Accident Pre-Cursor Incidents Safety – Capacity Relationship
ATL, BWI, LGA, DCA Haynie, GMU 2002

18 ATL Estimated Collision Probability
Collision probability per SRO for each combination Small-Heavy Leader - Trailer Small-Large Small-B757 Using TOPAZ collision risk model, we calculated the collision probability per simultaneous runway occupancy for each aircraft combination. It’s shown that the most possible collision case is that a heavy aircraft follows a small aircraft if they are involved in a simultaneous runway occupancy. The cases of a large aircraft following a small one and a B757 following a small are of the next top possibilities. Richard Y. Xie, GMU research in progress

19 Wake Vortex Accident Rate in Safety-Capacity Coordinates
30 Years 3 Years NLR Stochastic Analysis

20 System Network Effects
Aprox. 10 Major Hub Airports are Operating at D/C max > 0.65 Delays at these Airports spread Non-Linearly throughout the Network Runway Additions at one Airport May have Little Network Effect System-wide improvements have a Larger Effect than Individual Airport Improvements Except at Major Airports like ORD, LGA and ATL!

21 Major US Airport Congestion
Queuing Delays Grow Rapidly J. D. Welch and R.T. Lloyd, ATM 2001

22 Source: William DeCota, Port Authority of New York
Market Does Not Act to Minimize Delay or Maintain SAFETY: LGA Air 21 Impact Source: William DeCota, Port Authority of New York

23 Atlanta: A Maximum Capacity Fortress Hub Airport
2 Runways – Arrivals 2 Runways – Departures 50 Arrivals/Hr/RW – Max 72 Seconds Between Arrivals 8.5 minutes Average Delay 36 Delays/1000 Operations 38 min./delay

24 Simulated Auction Delay Benefit at ATL
45 min maximum schedule deviation allowed, no flights are rerouted Scheduled arrivals (#operations/quarter hour) Estimated Average Runway Queuing Delay (min) ATL reported optimum rate Loan Le Research in Progress

25 Observations – NAS Safety
We are approaching the Point that the existing system may be demonstrably less safe (at current and future capacity fractions) than a new, more synchronous, aircraft FMS/ADS-B separation based system System is Safe BUT Safety Margins are Diminishing! This case has not been Analyzed nor even Suggested as a RATIONAL for CHANGE to date!

26 Central Research Questions
Both Safety and Efficiency Concerns lead us to the conclusion that the network should be operated as a Synchronous System with economic incentives to use the largest aircraft affordable and economically viable Time Window Auctions at Airport Metering Fix may provide the Economic Incentives necessary to maximize/optimize Network Capacity Central Research Questions: How Synchronous Can We Make this System – All Weather? What Should the Design Target Level of Safety Be?

27 Backup Slides

28 Wake Normalized Aircraft Time Separation: LGA in VMC & IMC

29 Observed WV Separation Violations vs. Capacity Ratio
Haynie, GMU 2002

30 ATL Arrival - Departure IMC

31 ATL and LGA Inter-Arrival Time in IMC and VMC:32 - 39 Ar/Rw/Hr

32 Observations - Recommendations
FAA Culture – Barriers to Change NASA Culture – Barriers to Change State of NAS Safety Proposed Grand Experiment/OPEVAL

33 FAA Barriers to Change FAA has an Operational and Regulatory Culture
Inclination to follow training that has seemed to be Safe in the Past FAR has NOT Changed to Provide Operational Benefits from Introduction of New Technology Assumption that Aircraft Equipage would be Benefits Driven did not account for Lack of an ECONOMIC and/or SAFETY Bootstrapping Requirement

34 FAA Investment Analysis Primarily focus on Capacity and Delay
OMB requirement to have a B/C ratio > 1 leads to a modernization emphasis on Decreasing Delay In an Asynchronous Transportation Network operating near it’s capacity margin, Delay is Inevitable Delay Costs Airlines Money and is an Annoyance to Passengers BUT is Usually Politically and Socially Acceptable

35 NASA Barriers to Change
NASA has become more Process Oriented than Product Oriented Frequently Stated Objective of 25 year Implementation Goal Avoids Accountability and renders NASA TRL 4/6 Product unusable by either Government Agencies or Industry NASA needs a Cadre of Engineers/System Analysts with a long range goal of becoming the USG Technical Experts in Aviation System Safety Analysis

36 Proposed Grand Experiment: OPEVAL to FOCUS Efforts
FY 2008 One Year of Night Operations 12pm to 8 am DAG-TM + aFAST+CDM + WV Entire US Air Cargo Fleet Inter-Agency IPT DoT, NASA, FAA, DoD, NTSB, Boeing, CAA, Airlines

37 Hypothesis: Most Major Changes to the NAS have been due to Safety Concerns
1960’s Mandated Introduction of Radar Separation 1970’s Decrease in Oceanic Separation Standards Required a Landmark Safety Analysis 1970’s Required A/C Transponder Equipage 1970’s Required A/C Ground Proximity Equipage 1990’s Required A/C TCAS Equipage 1990’s Required A/C Enhanced Ground Prox. Equipage 1990’s TDWR & ITWS Introduction 1990’s Mandated Development of GPS/WAAS

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