Avoiding Gridlock in the Skies: Issues and Options for Addressing Growth in Air Traffic

Order Code RL32707

CRS Report for Congress

Received through the CRS Web

Avoiding Gridlock in the Skies:

Issues and Options for

Addressing Growth in Air Traffic

Updated January 19, 2006

(name redacted)

Specialist in Aviation Safety, Security, and Technology

Resources, Science, and Industry Division

Congressional Research Service ˜ The Library of Congress

Avoiding Gridlock in the Skies: Issues and Options for

Addressing Growth in Air Traffic

Summary

A major challenge facing aviation policymakers is developing a strategy for

increasing the capacity of the national airspace system to keep pace with projected

growth in demand for air travel. While Transportation Secretary Norman Mineta’s

vision for the next generation air traffic system aspires to triple system capacity by

2025, FAA projections suggest that capacity enhancements will struggle to keep pace

with growth in demand at major airports, in busy airspace around major metropolitan

areas, and along certain busy high altitude corridors. Factors, including the

continuing population shift into major metropolitan areas, the increased reliance on

smaller jets in both airline and general aviation operations, and increased point-topoint service, are expected to spur growth in those aviation operations that impact

high altitude airspace and contribute to increased congestion at capacity constrained

airports.

The current aviation system is constrained by limited available capacity at

critical major metropolitan airports and is increasingly unable to meet projected

future demand. The system also is constrained by outdated technology and

procedures that limit the utilization of available airspace. In addition to meeting

these challenges, the FAA also faces internal challenges to meet future controller

staffing needs given that almost half of its existing controller workforce is expected

to retire over the next decade. The FAA also faces significant challenges in

reforming its organizational culture which historically has been blamed for consistent

cost overruns, schedule slips, and performance shortfalls in major air traffic

modernization projects.

Two new organizations within the FAA — the Air Traffic Organization (ATO)

and the Joint Planning and Development Office (JPDO) — are viewed as key

elements of organizational reform that may be closely scrutinized by Congress and

administration policymakers to ensure that they effectively manage the

implementation of near term and long range capacity enhancement efforts. The key

challenges for these organizations is to develop and execute capacity expansion plans

that appropriately invest in airport infrastructure, air traffic system technology, and

operational procedures to keep pace with expected growth in demand for air travel

while maintaining or improving upon current levels of safety and efficiency.

Possible strategies for meeting these objectives include implementing free flight

concepts that will allow more autonomy and direct routing of aircraft to better

optimize airspace utilization; safely reducing aircraft separation standards to increase

capacity in crowded airspace; effectively implementing automation and decision

aiding technologies to improve airspace utilization and traffic flow; and expanding

and reconfiguring existing airport infrastructure. In addition, demand management

strategies, such as curtailing peak hour flights or implementing slots or quotas may

be examined as means to align demand with available capacity at congested airports.

The FAA’s investment strategy for meeting these capacity needs is also likely to be

of considerable interest in future years as significant funding challenges may arise

because of possible aviation trust fund shortages and a history of significant cost

overruns on major airspace modernization projects. [This report will not be updated.]

Contents

Factors Affecting Growth in Air Traffic Operations . . . . . . . . . . . . . . . . . . . . . . . 3

Impact of Overall Economic Growth on Aviation . . . . . . . . . . . . . . . . . . . . . 3

Population Growth in Metropolitan Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Increased Use of Smaller Jets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Regional Jets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Business Jets and Mini-Jets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Low-Cost Carriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Increased Point-to-Point Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The Future of Hubs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

The Net Effect on Capacity Straining Operations . . . . . . . . . . . . . . . . . . . . 15

Factors Affecting Airport and Airspace Capacity . . . . . . . . . . . . . . . . . . . . . . . . 16

Available Capacity at Major Airports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Airspace Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Controller Staffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

FAA’s Organizational Culture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Air Traffic Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Joint Planning and Development Office . . . . . . . . . . . . . . . . . . . . . . . 25

Cost Overruns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Impact of Under-capacity on Flight Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 29

The Summer of 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Some Possible Delay Remedies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

The Relationship Between Capacity and Delay . . . . . . . . . . . . . . . . . . . . . . 31

Impact of Congestion on Aviation Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Runway Incursions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Loss of Separation and Near Mid-Air Collisions . . . . . . . . . . . . . . . . . . . . . 39

Possible Strategies for Enhancing Capacity While Maintaining Safety and

Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

The “Free-Flight” Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Reducing Separation Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Automation and Decision Aiding for Air Traffic Management . . . . . . . . . . 48

Airport Expansion and Reconfiguration . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Market-Based Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

De-peaking Strategies and Incentives . . . . . . . . . . . . . . . . . . . . . . . . . 52

Slots and Quotas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Funding Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Status of the Airport and Airways Trust Fund . . . . . . . . . . . . . . . . . . . . . . . 55

FAA’s Facilities and Equipment Account . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Summary of Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

List of Figures

Figure 1. Population Growth in Metropolitan Areas Since 1950 . . . . . . . . . . . . . 5

Figure 2. Fleet Composition for Regional and Commuter Operators

(Passenger Aircraft > 30 Passenger Seats) . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 3. Fleet Utilization for Regional and Commuter Operators

(Passenger Aircraft) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 4. Fractional Ownership of Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 5. Historic Data and Forecast Growth for General Aviation and

Air Taxi Turbojet Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 6. Historic Data and Forecast Growth in Airborne Hours . . . . . . . . . . . . 15

Figure 7. Average Delay (1/1998 — 11/2005) . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 8. Percent of Flights Delayed (1/1998 — 11/2005) . . . . . . . . . . . . . . . . . 30

Figure 9. The Tradeoff Between Expanding Capacity and Mitigating Delay . . . 32

Figure 10, Runway Incursion Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 12. Continuum of Government Involvement in Market-Based

Strategies to Alleviate Aviation Congestion . . . . . . . . . . . . . . . . . . . . . . . . 51

Figure 13. Income and Uncommitted End of Year Balances in the Airport

and Airways Trust Fund . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Figure 14. FAA Facilities and Equipment Funding . . . . . . . . . . . . . . . . . . . . . . . 60

List of Tables

Table 1. Mitigation Strategies to Prevent Runway Incursions and Reduce

Their Severity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Table 2. Risk Elements and Considerations for Implementing Free Flight

Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 3. Projected Aviation Trust Fund Revenues Before and After

September 11, 2001 ($ Billion). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Avoiding Gridlock in the Skies: Issues and

Options for Addressing Growth in Air Traffic

The demand for air travel over the next 15 years is expected to grow

significantly necessitating the expansion of the national airspace system. Passenger

boardings are expected to increase by almost 60% compared to pre-September 11,

2001 levels.1 Systemwide, air traffic operations are expected to increase by about

15%, including a 30% growth in air transport and commercial operations. At the

nation’s 35 busiest airports, total operations are expected to increase more than 34%

by 2020. To expand system capacity to meet this projected growth, the Department

of Transportation has unveiled an ambitious plan calling for a threefold increase in

systemwide capacity over the next 15 to 20 years. However, at least in the near-term,

planned capacity enhancement projects are expected to lag slightly behind projected

growth in aviation operations. Therefore, to meet future demand novel approaches

may be needed to expand system capacity while maintaining system efficiency and

safety.

Speaking before the Aero Club of Washington in January 2004, Secretary of

Transportation Norman Mineta unveiled his plan for the future of the national

airspace system and set the bar for expanding its capacity:

Unless we act now, our leadership [in aviation and aerospace] is in jeopardy, and

we could be facing gridlock in our national airspace. ...Therefore, I have

launched an initiative to galvanize America’s energies to design the Next

Generation Air Transportation System. A cleaner, quieter system based on 21st

century technology that will offer seamless security and added capacity to relieve

congestion and secure America’s place as a global leader in aviation’s second

century. ...We will harness technology in a way that triples the capacity of our

aviation system over the next 15 to 20 years.2

Experts have expressed concerns that, unless the FAA addresses the impact of

anticipated growth in air traffic, flight operations are likely to be constrained by

under-capacity in the national airspace system, especially at the nation’s busiest

airports. While clearly a significant increase in capacity is likely to be needed,

tripling system capacity — as Secretary Mineta’s vision aspires to do — appears to

be an extremely lofty goal to attain. Nonetheless, additional capacity is especially

needed at several of the nations busiest airports that are already operating at or

1

Based on FAA Terminal Area Forecast (TAF) model.

comparisons use 2000 data as the comparison basis.

2

Pre-September 11, 2001

Remarks for the Honorable Norman Y. Mineta, Secretary of Transportation. Securing

America’s Place as Global Leader in Aviation’s Second Century. Aero Club of

Washington, Washington, DC, January 27, 2004. U.S. Department of Transportation, Office

of Public Affairs.

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slightly above their theoretical capacity limits during peak travel times and in poor

weather scenarios.3

In fact, if capacity could be doubled over the next 20 years, these enhancements

will likely be sufficient to provide enough headroom to accommodate projected

growth in aviation operations for about the next 30 years. However, many remain

skeptical whether even this goal is achievable and worry that, unless significant

changes occur, the national airspace system is destined to be constrained by undercapacity at the nation’s busiest airports and an inability to expand the infrastructure

and effectively implement technology and procedural changes to air traffic operations

to alleviate congestion and delay. These critics point to FAA’s historic failures to

effectively manage major acquisition projects, large looming costs for air traffic

operations and capacity enhancement projects, and possible shortfalls in the aviation

trust fund as major hurdles standing in the way of progress to fully implement the

next generation air transportation system (NGATS).

Several challenges have been identified that may limit the FAA’s ability to

significantly increase the capacity of the national airspace system over the next 15 to

20 years. One significant challenge is overcoming FAA’s traditional organizational

culture that has, in the opinion of many, failed to effectively develop a

comprehensive national strategy for enhancing capacity and failed to effectively

manage major acquisition efforts designed to address capacity needs.4 A second

factor is that there is a relatively high degree of uncertainty and risk associated with

many of the proposed programs designed to enhance capacity. While some of that

risk can be tied to FAA’s past performance in managing airspace modernization

projects, it should also be recognized that the complexity of the technology and the

national airspace system pose significant technical challenges that expose both shortterm and long-range plans for enhancing aviation capacity to considerable risk. A

third factor is the potential lack of available capital to fund capacity-related projects

and programs. Possible revenue shortfalls in the airport and airways trust fund and

potential cuts to the FAA’s facilities and equipment account could significantly

impede progress toward enhancing capacity. If these current funding challenges

persist, FAA is likely to face difficult decisions in prioritizing capacity enhancing

projects over the next several years.

This report examines: factors influencing the forecast growth and changing

characteristics of flight operations in the national airspace system; factors affecting

the ability to expand airport and airspace capacity to meet future demands; and the

impact of capacity constraints on flight operations and aviation safety. This report

also examines several possible strategies to expand system capacity, many of which

are being implemented or evaluated by the FAA and Congress. These strategies fall

into four broad categories: 1) airport expansion and infrastructure improvements; 2)

technology options to improve traffic flow and safely reduce aircraft separation; 3)

3

4

See Federal Aviation Administration. Airport Capacity Benchmark Report 2001.

See, especially, U.S. General Accounting Office. Air Traffic Control: FAA’s

Modernization Efforts — Past, Present, and Future.” Statement of Gerald L. Dillingham,

Director, Physical Infrastructure Issues Before the Subcommittee on Aviation, Committee

on Transportation and Infrastructure, House of Representatives, October 30, 2003.

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strategic plans and tactical tools to improve traffic flow and respond to delayinducing events; and 4) market based solutions to alter the demand characteristics of

flight operations at busy airports and in congested airspace. Finally, this report

examines the fiscal needs and funding challenges associated with implementing both

near-term and long-term programs to improve aviation system capacity.

Factors Affecting Growth in Air Traffic Operations

Several factors are expected to affect the growth in air traffic operations over the

next several years. Behind all of these factors is the country’s overall economic

growth. Another key underlying factor is the growth in U.S. population, and more

importantly, the population shift into major metropolitan areas and corresponding

economic growth in these areas. Additional factors include the increased use of

smaller commuter jets, more point-to-point routes for airline service, and significant

growth in business jet operations. The net result of these factors is a forecast

average annual growth rate of about 4.4% in airborne hours for airlines (including allcargo carriers), commuter operators, and business jets. These operations will most

significantly impact the busiest commercial and general aviation reliever airports in

the United States, airspace in major metropolitan areas, and certain busy high altitude

corridors.

Impact of Overall Economic Growth on Aviation

Future demand for aviation is likely to closely track projected growth in gross

domestic product (GDP). In fact, projected GDP growth is the main factor

considered in FAA’s forecast assumptions for aviation demand over the next 10 years

and has historically been an excellent long-term predictor of growth in the aviation

industry. Analysis of historic data from 1976 to 2003 indicate that the correlation

between GDP and passenger boardings is 0.97, and the correlation between GDP and

the total number of air carrier, air taxi, and other commercial operations is 0.94.5

Over the past few years, however, this has not been the case. The response to the

September 11, 2001 terrorist attacks, a decline in air travel during the initial phase

of the U.S. war with Iraq, and impact from the 2003 severe acute respiratory

syndrome (SARS) outbreak have all been identified as contributors to the significant

decline in aviation operations over the past four years that could not have been

foreseen. In fact, when the years between 2001 and 2003 are removed from the

analysis, the correlation between GDP and passenger boardings rises to almost 0.99

and the correlation between GDP and commercial operations is almost 0.97. As the

aviation industry recovers from these unprecedented events, passenger demand and

operations are expected to resume a track of growth that closely parallels the forecast

rise in GDP barring any unforeseen events that could significantly alter this projected

growth pattern.

5

CRS calculations of correlation between OMB historical data of GDP and FAA terminal

area forecast (TAF) historical data of systemwide enplanements and operations. Correlation

values measure how closely related two variable are and range between -1 and +1. Since

the correlations between GDP and passenger boardings and GDP and flight operations are

close to 1, these variables are considered to be closely related. However, this does not imply

that there is any causal relationship between these variables.

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While the FAA expects that other economic factors, such as the consumer price

index (CPI) and fuel costs, will have a negligible impact on forecast growth in

aviation operations over the next 10 years, anticipated changes in the shape of the

aviation industry may raise the significance of these factors in predicting future

demand for aviation operations. For example, rising fuel costs to the aviation

industry could drive up airline ticket prices thus slowing demand for air travel. Such

factors are likely to become more important considerations as the aviation industry

shifts toward a consumer base consisting of more leisure travelers whose purchasing

patterns tend to be more cost sensitive. Competition among low-cost carriers in a

market of cost conscious consumers with ready access to ticket pricing data over the

internet is likely to keep airline prices relatively low and demand high. The

emergence of other aviation options for business consumers, such as fractional

ownership programs for business jets and lower cost mini-jets, may result in further

shift the demand characteristics for airline travel and alter the composition of

operations in the national airspace system.

Population Growth in Metropolitan Areas

Since the end of World War II, major metropolitan areas have grown

significantly (see Figure 1). By 2000, more than 80% of U.S. residents were living

in metropolitan areas. Fifty of these metropolitan areas had populations greater than

1 million people and these areas were home to 57% of the total U.S. population.6

The resulting impact of the increasing population concentration in metropolitan

areas on aviation is reflected by a high density of air traffic operations and concerns

over capacity at a relatively small number of commercial and general aviation

reliever airports located within these major metropolitan areas. In fact, out of more

than 400 airports with commercial service in the United States, the FAA currently

identifies only 35 commercial airports in its near-term strategic plan for enhancing

the capacity of the national airspace system — the operational evolution plan (OEP).7

All of the airports listed in the OEP are located in major metropolitan regions with

more than one and one-half million inhabitants. These 35 airports, referred to as the

OEP-35 airports, handled 57% of all commercial operations at towered airports

between FY1999 and FY2002.

While capacity constraints, delays, and environmental considerations are likely

to be the most significant issues for these large metropolitan airports, the continued

availability and adequacy of service is likely to be a challenge for airports outside of

these major population centers, many of which have already lost air service as a result

of airline industry cutbacks.8 In other words, while major metropolitan areas are

likely to face challenges in meeting aviation capacity needs, airports in small cities

6

Frank Hobbs and Nicole Stoops. Demographic Trends in the 20th Century: Census 2000

Special Reports. U.S. Department of Commerce, U.S. Census Bureau, CENSR-4,

November 2002.

7

8

Federal Aviation Administration. Operational Evolution Plan (Version 6.0), 2004-2014.

Michael Allen. Crisis in Small Community Air Service. BACK Aviation Solutions: New

Haven, CT.

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may face difficulties in maintaining adequate air service. Thus, aviation capacity is

largely a geographically specific issue affecting service to and from major

metropolitan commercial and general aviation reliever airports and the flight

corridors interconnecting these major population centers.

Figure 1. Population Growth in Metropolitan Areas Since 1950

Percent of U.S. Population

100

80

60

40

20

0

1950

1960

1970

Suburbs

1980

1990

2000

Central Cities

Source: U.S. Census Bureau.

Besides population growth, high income growth in a metropolitan region may

increase demand for both airline travel and business aviation. Recognizing the

influence of both population and income growth in major metropolitan areas on air

traffic demand characteristics, the FAA and the MITRE Corporation’s Center for

Advanced Aviation System Development (CASSD) recently released a detailed study

of aviation capacity needs over the next 15 years.9

The study identified five airports across the country where additional capacity

is already needed: Hartsfield-Jackson Atlanta International (ATL), Newark Liberty

International (EWR), New York LaGuardia (LGA), Chicago O’Hare (ORD) and

Philadelphia International (PHL). Atlanta, Georgia was identified as the one

metropolitan area already in need of additional capacity because it lacks a second

commercial airport to offload some of the ATL traffic. However, the study found

that the completion of a fifth runway at ATL should meet Atlanta’s additional

capacity needs, at least until 2020.

The study concluded that by 2013, 15 airports will need additional capacity

improvements, assuming planned enhancements at airports are completed before

then. All three major airports in the New York metropolitan area (EWR, LGA, and

Kennedy International (JFK)) made the list as did three airports in the Los Angeles

9

Federal Aviation Administration and The MITRE Corporation. Capacity Needs in the

National Airspace System: An Analysis of Airport and Metropolitan Area Demand and

Operational Capacity in the Future. June 2004.

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area. If planned improvements don’t occur, the total number of airports needing

additional capacity may rise as high as 26.

According to the study, by 2020, the number of airports needing additional

capacity will grow to 18 assuming planned enhancements stay on track before then.

An additional 23 airports were identified as potentially needing additional capacity

by 2020 if planned improvements are delayed or cancelled. For some metropolitan

areas, the outlook is not particularly promising. In Los Angeles, for example, if

planned enhancements don’t occur, additional capacity will be needed at all major

commercial airports and two key reliever airports. Even with the planned

enhancements in place, the Los Angeles metropolitan area will face significant

capacity constraints in the next 10 to 15 years.

While major metropolitan areas like Los Angeles and New York face significant

challenges to meet aviation capacity needs over the next 15 years, capacity needs are

not limited to the largest metropolitan areas and the current busiest airports. For

example, the study found that the fast-growing metropolitan areas of Austin and San

Antonio, Texas, and Tucson, Arizona, while not included in the OEP-35, are

anticipated to have a significant need for additional capacity over the next 15 years

spurred by large economic growth. In sum, the capacity needs study identifies

significant challenges ahead for meeting aviation capacity demand in large and fastgrowing metropolitan areas.

Increased Use of Smaller Jets

Besides population growth in metropolitan areas, the shift toward using more

smaller jets in scheduled service and expansion of the business jet market is expected

to increase the operational load of the national airspace system.

Many are anticipating the arrival of Airbus A-380, the world’s largest

commercial airliner, which is expected to enter service in 2006. However, the A-380

is targeted at long-range international operations and is expected to have a negligible

impact on airspace capacity considerations domestically, especially since no domestic

passenger airline has placed an order for even one of these airplanes to date. In fact,

the projected trend in the domestic U.S. market is actually toward smaller jets rather

than larger jets both in the airline industry and also in charter and general aviation

operations. The net effect of large anticipated growth in the market and utilization

of these smaller aircraft is an expected increase in traffic at both commercial and

general aviation reliever airports.

Regional Jets. Regional and commuter airlines have been, and continue to

convert their fleets from turboprop aircraft to faster regional jets that appeal to

consumer demand for jet service. Regional jet manufacturers, chiefly Canadian

maker Bombardier and Brazilian manufacturer Embraer, continue to produce large

numbers of aircraft for the 50 to 90 seat regional market and are now developing

larger aircraft that will seat up to 120 passengers to compete with the Boeing 717 and

Airbus A319. FAA data indicate that the number of regional jets flown by regional

and commuter carriers has increased by about 550% since 1998. The growth in

regional jets is expected to continue, but at a reduced rate: the number of regional jets

is expected to double compared to current fleet size by 2015. This increase in

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regional jets will only be slightly offset by a modest decline in the use of turboprop

aircraft. Overall a net increase in regional and commuter fleet size of 50% over

current levels is forecast (see Figure 2).

Figure 2. Fleet Composition for Regional and Commuter Operators

(Passenger Aircraft > 30 Passenger Seats)

Source: FAA Aerospace Forecasts FY2005-2016.

While the size of the overall regional and commuter fleet (including turboprop

and turbojet aircraft) is anticipated to increase by 50% over the next 10 years, the

utilization of these aircraft is expected to increase by 60% over that same time period,

indicating an increased reliance on these smaller airplanes. Like fleet size, utilization

of commuter and regional jets is expected to increase more than twofold by 2015 (see

Figure 3).

However, skeptical industry experts have questioned these optimistic growth

projections for regional jets. These analysts point out that — along highly

competitive routes with competition from low-cost carriers — operating small jets

is more costly than operating larger jets simply because there are fewer revenuegenerating seats to offset the fixed unit operating costs. They reason that, if cost,

schedule, and other factors are relatively equal, consumers would rather travel on the

larger jets anyway. Skeptical analysts also caution that airlines have over-bought

regional jets in the 50 passenger seat size range, and there may soon be a glut of these

50-seat aircraft on the used aircraft market.10

Regional jets play a critical role in serving smaller markets. Their future,

therefore, depends to a large extent on airlines finding ways to make a profit serving

these markets. Since the regional jets have historically been run by network affiliates

10

Eric Torbenson. “Smaller jets lift profits, but have airlines overindulged?” The Dallas

Morning News, June 5, 2004.

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of major legacy air carriers, many of whom are now financially troubled, the once

certain prospects of continued growth in the regional jet market reflected in the FAA

forecasts is now much more doubtful. What there is greater certainty about, however,

is the forecast growth in passenger volume that is driving these trends. How regional

jets fit into the airlines strategic plans to meet this demand is much less certain.

Perhaps they will grow as forecast, or perhaps they will be replaced by large

passenger jets in many markets. If regional jet operations do grow as forecast, they

are likely to have a very large impact on system capacity, especially at busy hub

airports.

Figure 3. Fleet Utilization for Regional and Commuter Operators

(Passenger Aircraft)

Source: FAA Aerospace Forecasts FY2005-2016.

Business Jets and Mini-Jets. While negligible growth is expected in

operations of piston-engine and turboprop aircraft used for general aviation and air

taxi operations over the next 10 years, significant growth in business jets and very

small jet aircraft, referred to by many as mini-jets, is anticipated by some. Whether

this trend plays out as some anticipate will largely depend on the overall health of the

U.S. economy as the business jet marketplace has historically been very sensitive to

economic conditions. From an air traffic management standpoint, this projected

trend will likely have a large impact. These operations will likely place significant

demands on high altitude airspace, congested airspace around major metropolitan

areas, and particularly at general aviation reliever airports and those commercial

airports that have a fair amount of general aviation operations in addition to

commercial traffic.

Two specific trends are likely to spur continued growth in the business jet

market. These trends are the proliferation of fractional ownership programs and the

introduction of relatively low cost mini-jets. Both of these trends are viewed as

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opening up the aviation marketplace to many customers who previously viewed

aircraft ownership as cost prohibitive. The increased flexibility in trip scheduling and

available airports that business jets can operate in and out of, coupled with the ability

to avoid many of the hassles of airline travel, such as parking, ticketing, and security

screening, is likely to prompt business travelers and corporations to consider

fractional ownership programs and mini-jets as alternatives to airline travel.

Fractional Ownership. One specific source of the large growth in business

jet operations is the exponential growth in fractionally owned aircraft. In fractional

ownership arrangements, corporations or individuals purchase an interest in as little

as 1/16th of an airplane (or 1/32nd of a helicopter) and typically pay a fixed fee for

operations and maintenance. Large fractional ownership management companies like

NetJets and Bombardier Flexjet provide fractional owners with access to all

comparable and smaller sized aircraft in their fleet thus providing owners with ondemand access to a entire fleet of business jets at a small fraction of the typical

purchase and operating cost of just one airplane. In essence, this arrangement

provides the fractional owner with a fixed number of hours of flight time usage in a

jet of a particular size each year. More recent innovative approaches, such as the

Marquis Jet Card program offered by NetJets, allow businesses and individuals to

purchase flight time in 25-hour increments, thus providing access to business jets at

an even lower cost than buying into a fractional ownership program.

Fractional ownership programs and charter flight-time purchase programs like

the Marquis Jet Card are likely to attract a significant number of corporations and

individuals to business aircraft operations who would have otherwise viewed the

costs of owning and operating business aircraft to be prohibitive. The fractional

ownership concept — although first introduced in the mid 1980s — was still virtually

unheard of 10 years ago. However, over the past 10 years, fractional ownership

programs have seen exponential growth (see Figure 4). In the last four years,

fractional ownership has grown by 62%. This trend is expected to continue. Experts

believe that only a small amount of the potential for fractional ownership has been

developed so far, and forecasts estimate that the number of fractional shares will

reach 7,000 and the total number of fractional aircraft will be about 1,200 by 2007.

Fractional ownership is expected to account for about 100 aircraft deliveries per year

through 2012. By then, fractional aircraft are expected to comprise almost 1/4th of

the business aircraft market.11

11

National Business Aircraft Association. NBAA Business Aviation Factbook 2004.

Washington, DC.

CRS-10

Figure 4. Fractional Ownership of Aircraft

7000

6217

5827

Fractional Shares

6000

4871

5000

3834

4000

3000

2607

2000

1551

957

1000

0

3

1986

158

5 26 51 57 71 84 110

1988

1990

1992

285

1994

548

1996

1998

2000

2002

Year

Source: National Business Aircraft Association. NBAA Business Aviation Factbook

2004.

Very Light Jets. Another trend that is likely to attract new customers to the

business jet marketplace in the near future is the anticipated entry of several low-cost

very light jets (VLJs), with typical seating configurations for 5-6 passengers. The

VLJs currently under development will have cruise airspeed capabilities of about 400

miles per hour and will fly along high altitude routes (above 18,000 feet) along with

airliners and larger business jets. First generation mini-jets such as the Eclipse 500

jet and Adam Aircraft A700 Adamjet are expected to enter full scale production in

2007 and will sell in the $1-1.5 million price range. Not to be outdone by these new

entrants, established business jet manufacturers like Cessna and RaytheonBeechcraft, are now offering small entry-level jets as well.

These aircraft may not be limited to just private or business use. For example,

Donald Burr, founder of People Express, and Robert Crandall, a former CEO of

American Airlines, have teamed to form a startup air taxi corporation and placed a

75 aircraft order for the A700 AdamJet.12 The mini-jet concept is too new to foresee

whether they will attract a sizable market for air taxi operations. Historically, air taxi

operations using small aircraft have met with only limited success anywhere besides

Alaska, Hawaii, and in some western states because of consumer reluctance to fly on

small airplanes. The ultimate success of ventures such as these will likely depend on

12

Adam Aircraft Industries, Inc. Adam Aircraft Announces $150 Million Order For Its New

Breed Of Personal Jets. Press Release. Englewood, CO, May 24, 2004.

CRS-11

the ability to establish a well proven safety record for these small jets. Success is

also likely to depend heavily on identifying and exploiting niche markets where such

service can provide a cost effective alternative to other modes of transportation.

While the overall impact of newly introduced and forthcoming mini-jets remains

largely unknown, the market for mini-jets, particularly from fractional ownership

programs and private owners appears promising for manufacturers. With so many

companies vying for a stake in the mini-jet market, clearly there are great

expectations of high demand for these airplanes.

The net effect of these trends — the proliferation of mini-jets and fractionally

owned business jets — will likely be a significant increase in general aviation and air

taxi jet operations. This is important because these operations, unlike typical general

aviation operations using smaller piston-engine airplanes, will impact high altitude

airspace and airspace around major metropolitan areas to a much greater extent. By

2015, the fleet size for general aviation and air taxi jets is expected to double and the

total usage of these aircraft, expressed in terms of hours flown, is expected to

increase by 80% (see Figure 5). This growth is significant because general aviation

and air taxi operations — a sector that is not nearly as visible as the airlines to most

observers — is expected to maintain about 20% of the share of those flight operations

that impact congested airspace.

Figure 5. Historic Data and Forecast Growth for General Aviation

and Air Taxi Turbojet Operations

Source: FAA Aerospace Forecasts FY2005-2016.

CRS-12

Low-Cost Carriers

Another trend that is already shaping growth in aviation operations is the

increasing prevalence of low-cost passenger air carriers. Low-cost carriers is a term

used to refer to airlines whose business models generally involve simplified pricing

schemes and service along mostly point-to-point routes. Examples include AirTran,

Spirit, Frontier, Independence Air, Southwest, and JetBlue. By comparison, legacy

carriers, the other segment of the airline industry, employ business models that

consists primarily of hub and spoke systems where smaller markets are linked to a

carrier’s network through large hub airports such as Atlanta, Chicago, Dallas-Fort

Worth, Minneapolis-St. Paul, Detroit, Denver, Charlotte, and so on.

In a recent study comparing low-cost airlines to legacy carriers, the GAO found

that, despite major efforts to cut expenses, legacy airlines have been unsuccessful in

sufficiently reducing costs to be competitive with low cost carriers.13 Unit costs, a

key determinant of profitability in competitive markets, are significantly lower at

low-cost airlines largely due to lower labor and asset-related costs. Consequently,

several low cost carriers have been able to maintain profitability in the weak postSeptember 11, 2001 market for air travel whereas legacy carriers have collectively

lost billions of dollars. In response to the growth of low-cost carriers, several major

carriers have launched spinoff operations that mimic the business model of low-cost

carriers. Examples include Delta’s Song and United Airline’s Ted.

Presently, with four legacy airlines in bankruptcy and escalating fuel prices,

low-cost business models and practices have been adopted by many as a means of

controlling costs. However, adopting a low-cost carrier model is not by any means

a guarantee of success as demonstrated by the recent demise of Independence Air —

a former regional partner of United Airlines that struggled in its short history as a

low-cost competitor and closed its doors in early January 2006. Also, while United

is forging ahead with its subsidiary, Ted, as part of Delta’s restructuring, the Song

brand is being eliminated, and Song airplanes are being reintegrated with Delta’s

mainline fleet. Over the past five years, the industry has been very dynamic, which

likely created some oversupply of flights in the market placing additional strain on

capacity. Many industry experts believe that this situation is unsustainable and that

ultimately a marketplace with fewer carriers and higher load factors (filled seats on

flights) will prevail. A sharp increase in fuel prices during 2005 has prompted

airlines to restructure schedules to increase load factors as much as possible. While

such factors may reduce congestion somewhat in the short term, this may be offset

by the low-cost carrier model which relies more heavily on point-to-point service.

This may result in an increased concentration of flights on very specific routes, such

as between Northeast cities and Florida destinations, as compared to the hub-andspoke model used by legacy carriers which, on the other hand, tends to concentrate

operations at specific hub airports like Atlanta and Denver.

13

United States General Accounting Office. Commercial Aviation: Despite Industry

Turmoil, Low-Cost Airlines Are Growing and Profitable. Statement of JayEtta Z. Hecker,

Director, Physical Infrastructure — Testimony Before the Subcommittee on Aviation,

Committee on Transportation and Infrastructure, House of Representatives. GAO-04-837T,

June 3, 2004.

CRS-13

Increased Point-to-Point Service

The hub and spoke system offers extensive flexibility in routing and centralizes

operations in a manner that can limit the impact of maintenance and operationsrelated delays and cancellations at airlines’ hub facilities. However, the hub and

spoke system is susceptible to weather-related delays and cancellations due to

thunderstorms, heavy snow, or other extreme weather conditions at hub locations.

On the other hand, point-to-point service — favored by many of the low-cost carriers

— is less susceptible to having weather-related delays impact large portions of their

operations. However, this type of operation is more susceptible to maintenance- or

operations-related delays because their network is more decentralized and therefore

the availability of maintenance and operations support is more limited.

There is little doubt that, in order to survive, airlines will increasingly adopt

low-cost strategies to control costs and maintain or achieve profitability. What is less

certain is: to what degree will low cost airline operations continue to rely on point-topoint operations, and if and to what extent will growing low-cost carriers evolve their

operations into a hub-and-spoke model? Given that there are advantages and

disadvantages to both operational models, hybrid models that incorporate best

business practices of each are likely to emerge.

To some degree legacy carriers are already implementing hybrid operational

models as a means to reduce costs. For example, American Airlines has implemented

what they call a rolling-hub or a hub de-peaking strategy, in which they have reduced

the number of connecting flights through their main hubs such as Dallas-Forth

Worth, TX (DFW). The strategy results in longer waits for connecting flights on

average. While this strategy reduces operating costs by reducing the number of

flights, because of the longer layovers it may be less appealing to consumers,

especially in markets where alternative point-to-point service is available from lowcost carriers. While such a model may have the effect of reducing congestion at

hubs, its long term system-wide impact on capacity will largely be determined by

consumer demand characteristics which may favor point-to-point service in some

cases, particularly along busy, competitive routes.

The ability to address national airspace system capacity needs to a large extent

hinges on the ability of policymakers to foresee how these market-based trends will

affect airline business practices in the future. In this evolving marketplace for

aviation services, policymakers may need better tools for modeling and predicting

market factors and examining the effects of capacity enhancement efforts in the

larger context of changing demand characteristics on the aviation system . Nowhere

is this more true than in predicting future traffic at major hubs, especially since a

large proportion of these hub operations are tied to specific business practices of

financially troubled air carriers.

The Future of Hubs

As low cost carriers continue to compete by offering more point-to-point service

in selected markets and legacy carriers follow suit, experts have raised questions

about the future prospects for some of the nation’s busiest hub airports. For example,

CRS-14

U.S. Airways significantly scaled back flight operations from its Pittsburgh (PIT) hub

to cut costs.14 Since PIT does not have a high volume of origination and destination

passengers despite having a metropolitan area population of more than 2 million, it

is unlikely that a competitor will pick up the slack. In the current economic

environment, where legacy carriers operating hub-and-spoke networks continue to

seek cost cutting measures, the outlook for just about any secondary hub is uncertain.

For US Airways, who also operates hubs in Charlotte, North Carolina (CLT) and

Philadelphia (PHL), PIT is seen as having very little strategic importance in its

current restructuring plan and is not considered an attractive location for any other

carrier to fill in the gaps left as US Airways scales back operations.15

For other secondary hubs, like Delta Airline’s Salt Lake City (SLC) operation

and Delta Connection’s Cincinnati/Northern Kentucky (CVG) facility, the future is

also uncertain. Prior to Delta’s bankruptcy filing, traffic at SLC continued to lag

behind other Delta hubs and Delta moved to reduce mainline flights there and

increase the presence of its regional partner’s Delta Connection flights. Whether

large legacy carriers will be able to maintain and grow their multi-hub networks

remains questionable, and in the short-term, more consolidation of hub operations

may occur. What may also occur, with the shift toward more regional jet operations,

is the expansion of regional jet hubs like Delta Connection’s Cincinnati/Northern

Kentucky (CVG) facility. Regional hubs, where regional partners can link to

mainline flights, appeared to be a major focus of Delta’s restructuring efforts prior

to entering bankruptcy, although since filing for bankruptcy Delta has scaled back

flights at CVG by almost 25%. Despite this change of course, other airlines may

shift toward more regional jet operations and manufacturers remain optimistic about

the utilization of larger regional jets in the 70-100 seat range as compared to

declining utilization for 50-seat models. Northwest Airlines, also restructuring under

bankruptcy protections, recently announced plans to launch a new low-cost

subsidiary, tentatively named NewCo, in 2007 that will operate these larger regional

jets.16 If and how this restructuring will impact operations at Northwest’s hubs in the

long term remains unclear.

Knowing where future hubs operations will be concentrated is obviously of

particular interest for understanding future capacity needs. However, besides the

major hubs and major population centers, where continued high volumes of

operations are likely, the long-range outlook for specific large airports may be hard

to predict. For example, Saint Louis-Lambert Field (STL) lost its status as a major

hub when American Airlines bought TWA. As a result, airline operations there have

dropped by 60% there over the past four years. However, STL’s geographically

central location and existing hub infrastructure could make it an attractive hub

location in the future for regional operations or perhaps an expanding low-cost

carrier. While the location of possible future hubs is difficult to foresee, the impact

of certain distributions of operations on the national airspace system can be modeled

14

Steve Lott. “US Air May Cut One-Third of PIT Departures In November.” Aviation

Daily, July 21, 2004.

15

“Are Hubs An Endangered Species?” Airline Business Report, 22(3), January 19, 2004.

16

“Northwest To Launch Low-Cost Carrier In ‘07.” Brandweek, January 9, 2006.

CRS-15

and simulated so that decision-makers and airspace planners can be better poised to

address different growth patterns in aviation operations as they unfold.

The Net Effect on Capacity Straining Operations

The aforementioned trends are expected to contribute to increased flight

operations in capacity constrained areas of the national airspace system. The types

of flight operations considered most likely to be limited by capacity constraints

include operations: in high altitude airspace (airspace above 18,000 feet referred to

as Class A airspace); in congested airspace around major metropolitan areas (Class

B and some Class C airspace); and at busy commercial airports and general aviation

reliever airports in major metropolitan areas. Flight operations of 1) airliners, 2)

commuter and regional operators, and 3) general aviation turbine-powered aircraft

are considered most likely to impact capacity constrained airports and airspace.

Overall airborne hours in these three categories of operations are expected to increase

by 44% over the next 10 years (see Figure 6). The largest percentage growth in

airborne hours is expected to be in jet-powered general aviation aircraft (95%),

followed distantly by large air carriers flying both passenger and cargo operations

(39%). The expected growth in airborne hours among regional and commuter

aircraft will not be quite as large, but will nonetheless be significant (34%). Large

carrier operations, which currently represent 64% of total airborne hours among these

three categories, will grow more slowly than general aviation jet and commuter and

regional operations. By 2015, large carrier operations are expected to still make up

61% of these capacity straining operations, only three percent less than the current

level. Nonetheless, the composition of flight operations 10 years from now could be

quite different than today with smaller jets, and particularly general aviation

turbojets, accounting for a larger percentage of the mix.

Figure 6. Historic Data and Forecast Growth in

Airborne Hours

Source: FAA Aerospace Forecasts FY2005-2016.

CRS-16

Factors Affecting Airport and Airspace Capacity

Based on FAA forecasts and capacity growth assumptions, the projected growth

in aviation operations is likely to outpace projected capacity expansion for the

foreseeable future at major metropolitan airports, in crowded terminal airspace

around major metropolitan regions, and along certain high altitude corridors.

According to the latest version of the FAA’s Operational Evolution Plan (OEP),

while system-wide capacity has increased about 6.5% over the past four years, it is

expected to increase by only 27% by 2013 compared to the effective capacity in

2000. While this reduction in projected capacity enhancement may simply be a

reflection of different forecasting methods or assumptions or a reflection that

capacity enhancements in the previous plan were realized sooner than expected, it

could also be a preliminary indicator of a future slowing trend in capacity growth.

There is a potential concern that beyond the 10-year time frame examined in the

OEP, there may be a diminishing marginal gain in capacity over time. In other

words, unless new approaches are applied to the problem of aviation capacity as part

of a long term strategy, it may become more and more difficult to enhance systemwide capacity using methods applied in the OEP beyond this time frame. Several

factors including available capacity at major airports, current airspace design, air

traffic controller staffing, and the FAA’s organizational culture could provide unique

challenges to enhancing the capacity of the aviation system to meet the growth in

demand for aircraft operations.

Available Capacity at Major Airports

To assess available capacity at the nations busiest airports, the FAA conducted

capacity benchmark studies in 2001 and 2004, detailing the available capacity at

these airports and comparing this available capacity to actual traffic levels.17 In 2001,

the FAA released its initial capacity benchmark report detailing the maximum

number of hourly flights that can be accommodated at the nation’s 31 busiest

airports.18 This study defined the envelope of aircraft arrival and departure rates at

these airports under optimum, good weather, conditions and under reduced rate

conditions when visibility requires radar separation standards and procedures to be

implemented. The study found that many of the busiest airports, including the eight

most delayed airports, operated close to their available capacity levels and sometimes

exceeded these levels during peak hours, especially when these peak periods

coincided with poor weather conditions. Capacity loss due to weather can be quite

significant, but varies significantly from airport to airport depending on differences

in runway configurations and foul weather procedures. Airports such as Cincinnati

(CVG) and Minneapolis-St. Paul (MSP) have a minimal capacity loss during bad

17

Federal Aviation Administration. Airport Capacity Benchmark Report 2001; Federal

Aviation Administration and The MITRE Corporation. Airport Capacity Benchmark Report

2004. September 2004.

18

In earlier versions of FAA’s OEP, only 31 airports were listed. The list of OEP airports

has now grown to 35.

CRS-17

weather, whereas some airports, like STL and San Francisco (SFO), may lose as

much as 40 percent of their available capacity when visibility drops.

The revised benchmark study released in September 2004, modified the

methodology slightly to examine capacity under three different weather scenarios:

optimum, marginal, and low visibility — instrument flight rules (IFR). The study

was expanded to include the four airports added to the list of major airports in the

operational evolution plan (OEP) and now provides benchmarks for all OEP-35

airports.

The 2001 benchmark study examined forward-looking projections of capacity

enhancement by 2010 assuming planned runways and new technologies would be in

place by that time while the 2004 benchmark study projected future benchmarks for

the OEP-35 airports in 2013 under the same assumptions that planned capacity

enhancement work was completed by that time. While the 2001 study found that

many capacity enhancement projects, such as new runways and new technologies,

were planned or underway, the cumulative capacity enhancement of these projects

often fell short of keeping up with projected growth in demand. In fact, at each of

the top six airports in terms of delays, projected growth was expected to outpace

planned capacity enhancements, on average, by over 9% percent in good weather and

by more than 10% during reduced visibility operations. Among the 8 airports

identified in the study as experiencing significant passenger delays, growth in

demand through 2010 was expected to average 14.8%, while runways and

technologies were expected to increase capacity, on average, by only 8.6% in good

weather and 7.7% during reduced visibility operations over this time period.19 Not

surprisingly, the benchmark study concluded that the top six most delayed airports

plus Los Angeles International Airport (LAX) — ranked 12th overall in passenger

delays at the time of the study — would continue to experience significant passenger

delays through 2010. The 2004 benchmark study did not provide growth projections

to make similar comparisons. However, based on the fact that the 2004 benchmark

projections of capacity enhancement achievable by 2013 are comparable to those

projected for 2010 in the 2001 benchmark, the expectation is that growth in aviation

operations will continue to outpace system-wide capacity expansion.

Other trends observed in the 2001 benchmark study further indicate that, despite

ongoing and planned expansion projects, many airports will be unable to keep up

with projected growth in demand. For example, Orlando International Airport

(MCO), the most popular domestic leisure travel destination, is expanding to address

an anticipated growth in demand of 42 percent by 2010 compared to 2000 levels.

However, the combined impact of both a new fourth runway, now in operation, and

air traffic technologies is expected to enhance capacity by only 28% in good weather

and 38% in poor weather. While this expansion is significant, it is not expected to

keep pace with projected growth. While MCO is expected to see the largest increase

in demand through 2010 of the 31 airports studied, several other airports are expected

to be unable to increase capacity to meet their anticipated demand growth as well.

19

CRS calculations based on projections for each of the airports provided in: Department

of Transportation, Federal Aviation Administration. Airport Capacity Benchmark Report

2001.

CRS-18

Of the 31 airports studied in the 2001 benchmark, only 6 are anticipated to grow

their capacity at levels sufficient to clearly outpace projected growth in demand

through 2010. One of those airports is the Atlanta Hartsfield-Jackson International

Airport (ATL), where the addition of a fifth runway — expected to be completed in

June 2006 — coupled with enhanced air traffic technologies and procedures is

expected to increase capacity by 37% in good weather and 34% in restricted visibility

by 2010. By comparison, projected growth at ATL during this period is expected to

increase by 28%. Consequently, the study concludes that these actions are likely to

alleviate delays.

For the past three years, the downturn in demand for aviation since September

11, 2001, has alleviated some of the need to implement this technology in the near

term. However, anticipated future growth is likely to prompt the need for

implementing these types of capacity-enhancing capabilities. The 2001 benchmark

study concluded that new runways, which were planned at 14 of the 31 airports

examined, can provide the most significant increases. Forecast increases on the order

of 30 to 60 percent appear achievable at most airports from the addition of new

runways. For some airports, that already have high capacity layouts like Denver

(DEN), an additional runway provides a much smaller gain in capacity. And in

some cases, new runways do not appear to be the solution to increasing capacity at

all. Specifically, the 2004 benchmark points to Boston’s Logan International Airport

(BOS) as a location that will not be able to expand capacity by adding a new runway.

The new runway at BOS, expected to open in 2006, is anticipated to have no impact

whatsoever on increasing capacity. However, the new runway is expected to mitigate

delays during poor weather assuming ground infrastructure and environmental

constraints support the operational plans for this runway.

Despite some exceptions like Boston, building new runways is seen as having

the largest system-wide impact on expanding capacity. In addition, technology

enhancements are seen as providing additional capacity gains in the range of 3% to

8%, and procedural enhancements could provide another 5% to 10% gain in available

capacity at airports. While technology and procedural solutions will play a small but

important part of expanding capacity at airports, they are likely to play a more central

role in expanding the capacity of en route and terminal airspace.

Airspace Design

The national airspace system has evolved over the years into its present day

form consisting of a web of routes interconnected by ground based navigational aids

called very high frequency omnidirectional range (VOR) stations. These routes, or

airways, are often likened to highways in the sky. Along these airways, instead of

using lanes, opposite direction traffic is separated by altitudes. However, restricting

airplanes to airways does not make use of all available airspace. This can create

congestion on the airways which is compounded by large vertical separation

requirements implemented to keep aircraft at safe distances that were established

decades ago to allow for errors in altitude equipment and altitude deviation by pilots

that today can be effectively controlled by more precise instrumentation and cockpit

automation to detect and prevent unintended altitude deviations. Also, following

airways sometimes requires zig-zagging between points along the airway rather than

proceeding directly to the destination airport. While, these maneuvers only add a few

CRS-19

extra minutes to a typical flight, the additional fuel burn can be very significant for

an airline or aircraft operator. Therefore, flying the most direct routes between origin

and destination can be beneficial for air traffic management as well as operational

efficiency. FAA is currently laying the regulatory and operational frameworks for

such operations — referred to by many as free flight — based on precision satellite

navigation capabilities using the Global Positioning System (GPS) augmented by

ground-based signals to better pinpoint an aircraft’s position in space.

Besides limitations imposed by the current airway system, high altitude airspace

is also limited by the number of available altitudes, or flight levels (FLs), that

airplanes can travel on. Opposite direction traffic has historically been separated by

2,000 foot altitude spacing above 18,000 feet to ensure adequate separation in cases

of instrument or pilot error. However, with improved altitude measurement and

monitoring capabilities, the FAA is phasing-in the use of 1,000 foot altitude spacing.

This reduction in altitude spacing down to 1,000 feet, referred to as reduced vertical

separation minimums or RVSM, has virtually the same effect as doubling the number

of lanes on an interstate highway. RVSM is initially being implemented between

29,000 feet and 41,000 feet (FL290 to FL410). It has already been implemented

between these altitudes on ocean-crossing flights, and will be implemented in

domestic airspace by January 2005. Airplanes must meet special equipment

requirements to operate at these altitudes. RVSM will likely be expanded to include

all high altitude airspace (above 18,000 feet, specifically, FL180 to FL600) in the

future.

In order to manage and control the flow of high altitude traffic, airspace is

broken up into regions, or centers, which are further subdivided into sectors. One

significant factor affecting the design of the national airspace system and its capacity

is air traffic controller workload. Current demand characteristics result in a

concentration of east-west operations in airspace between Chicago, Boston, and

Washington, DC. The high altitude airspace monitored by controllers in Cleveland

Center is especially busy as this tends to be the bottleneck for flights transiting

between the West Coast and Chicago and cities in the Northeast. There is also a

heavy concentration of north-south traffic between Norfolk and Richmond, Virginia

and New York, and to a lesser extent along the California coast, especially between

Los Angeles and San Francisco. In these areas controller workload and the

segmentation of airspace to manage that workload can be a significant constraining

factor affecting capacity in high altitude airspace.

The strategies that the FAA has adopted to address these constraints is heavily

focused on the use of technology, automation, and pilot and controller decision aids

along with airspace redesign to assist with both the management and control of air

traffic in high altitude airspace. These initiatives are discussed in further detail in the

section titled The “Free Flight” Concept.

Controller Staffing

Another challenge facing the FAA is maintaining an adequate staff of air traffic

controllers (ATCs) to meet operational needs. In the past, between 1 and 2 % of the

controller workforce became eligible for retirement each year. There is a current

upward trend in the percentage of controllers that will be eligible for retirement,

CRS-20

which has currently risen to between 3 and 4% per year and will peak at almost 10%

per year in 2007 and remain above 5% per year through 2011. The FAA has

estimated that 7,100 controllers, roughly 45% of its current workforce, will retire

over the next eight years.20

Several factors are contributing to high demand for air traffic controllers over

the next 10 years. Foremost is the hiring wave in the early 1980s that occurred

following the 1981 dismissal of over 11,000 striking controllers. Since an air traffic

controller career in the United States is structured around a 25-year service model,

it is to be expected that those hired in 1982, as many current controllers were, would

be at or near the end of their careers by 2007. Another factor is the lengthy training

required to fully train and certify an air traffic controller which typically takes about

two to four years to complete, depending on the area of specialization. As controllers

retire, shortages of fully trained controllers for specific positions could occur,

especially if staffing allocations and appropriate training is not initiated well in

advance of anticipated retirements. Another factor affecting controller staffing is the

high labor costs for ATCs. These high labor costs are heavily influenced by the fact

that many controllers are at senior levels in the pay scale and under-staffing at many

facilities requires extensive use of overtime.21 The potential impact of these high

labor rates on addressing staffing shortages is that it may take away from available

funding needed to recruit, hire, and train the next generation of ATCs.

However, the number of air traffic controller positions is actually expected to

increase only modestly — at a rate slightly greater than 1% per year — through

2012.22 Therefore, other than addressing the pending wave of retirements and filling

vacant slots at air traffic control facilities during that time, it is not expected that

there will be significant expansion in the numbers of controllers needed. Rather,

staffing requirements are expected to be relatively flat for the foreseeable future. In

the long term, the increased use of automation and implementation of free flight

concepts may reduce some demand for controllers and shift some controller functions

to more strategic air traffic management positions. Airspace redesign to address

controller workload in busy airspace could create a need for some additional

controller positions. However, little overall growth in the total number of air traffic

controller positions is anticipated. Future technological advances could, however,

result in a shift in where controllers are needed. The implementation of free-flight

concepts coupled with terminal airspace redesign in busy metropolitan areas may, for

example, result in fewer controllers being needed to operate en route facilities and

an increased demand for controllers in terminal radar approach control (TRACON)

facilities, especially in major metropolitan areas.

20

U.S. General Accounting Office. Federal Aviation Administration: Plan Still Needed to

Meet Challenges to Effectively Managing Air Traffic Controller Workforce. Statement of

JayEtta Z. Hecker, Director Physical Infrastructure Team Before the Subcommittee on

Aviation, House Committee on Transportation and Infrastructure. June 15, 2004, GAO-04887T.

21

Department of Transportation, Office of Inspector General. FAA’s Management of and

Control Over Memorandums of Understanding. AV-2003-059, September 12, 2003.

22

Based on Bureau of Labor Statistics employment data for 2002 and 2012 projections.

CRS-21

Controller staffing is currently an issue of particular interest in Congress.

Vision 100 (P.L. 108-176) requires the FAA to submit annual air traffic controller

staffing plans, including strategies to address anticipated retirement and replacement

of air traffic controllers and requires a comprehensive human capital workforce

strategy to determine the most effective method for addressing the need for more air

traffic controllers. The FAA’s plan, released in December 2004, calls for hiring

controllers at a faster rate over the next 10 years to offset the wave of retirements and

improve selection and training. The FAA also anticipates that improved workload

efficiency and scheduling practices will reduce projections of staffing needs by 10%

over the next 10 years. However, the DOT Inspector General’s office has noted that

the FAA needs better location-specific projections of attrition rates to better gauge

future staffing needs.23 FAA’s initial plan did not include this location-specific

information on future staffing projections. However, the FAA is working on a

detailed assessment of staffing needs for each facility based on size, complexity, and

traffic volume.

Various options are under consideration to address the FAA’s ATC staffing

needs and funding challenges associated with meeting these staffing requirements.

One proposal offered has been to either grant age waivers to controllers allowing

them to work beyond 56, or to raise the statutory retirement age. Proponents of

raising the retirement age indicate that with better health and wellness of aging

adults, controllers may be able to perform safely and efficiently at older ages.

Research on cognitive performance of aging ATCs and the potential long term health

effects of ATC workload and stress, however, is contentious and does not provide

clear-cut answers to policy questions regarding the appropriate retirement ages for

controllers. A similarly contentious issue is the mandatory retirement age of 60 for

airline pilots. In both of these cases, the establishment of a retirement age is based

loosely on the research findings of medical and performance studies of aging and

long range effects of job-related stress, but is influenced by other factors such as

annuity calculations for retirement.

In general, research shows a gradual decline in cognitive abilities beyond age

30 that becomes more pronounced in the span between 60 and 70 years. Not

surprisingly, there are large individual differences that make pinpointing a specific

age where skills and abilities to perform ATC tasks decline precipitously. While

ATCs have to pass annual health exams, these only provide a very cursory evaluation

of cognitive abilities. Therefore, the potential impact of raising the ATC retirement

age above 56 or granting waivers on system safety is largely unknown. For this

reason, proposals to raise the retirement age are likely to be contentious.

In the near term, raising the retirement age could put off the need to hire and

train new ATCs for a few years and lessen the impact of pending retirements by

23

Statement of Alexis M. Stefani, Principal Assistant Inspector General, U.S. Department

of Transportation. Before the Committee on Transportation and Infrastructure,

Subcommittee on Aviation, United States House of Representatives. Addressing Controller

Attrition: Opportunities and Challenges Facing the Federal Aviation Administration. June

15, 2004.

CRS-22

spreading them over a longer time span. Such a strategy could be effective in helping

FAA to better meet annual hiring requirements.

Other proposals, such as modifying annuity calculations to reward ATCs for

additional years of service beyond their eligible retirement date or providing retention

bonuses as incentives to experienced controllers to stay in their positions may also

be considered as tools to spread the projected retirement wave out over a greater

number of years. However, any such proposal is likely to be controversial as it would

create a funding impact that may limit the FAA’s resources to hire and train

replacement controllers. Also, many believe that ATC labor costs at the FAA are

already too high.

Freezing or limiting wages of current controllers is also viewed by some as a

possible option to free up funds for hiring and training new ATCs, but this option has

several disadvantages. First, the cost savings would likely take a few years to have

a great enough impact to provide the needed funding for hiring and training

replacement ATCs. Second, such action may prompt current controllers to enter

retirement at a faster rate, thus negating the intent of the action. And finally, freezing

wages could have a negative effect on recruiting efforts if prospective applicants

view it as an indicator of future salary potential with the FAA.

The FAA is also mulling the idea of requiring newly hired ATCs to pay for their

initial training as a means to reduce the federal burden of training the next generation

of air traffic controllers. While the FAA notes that many airline pilots must pay for

their initial training, this option may significantly limit the pool of interested

applicants for ATC positions, especially given that the marketplace for applicants

with technical aptitude similar to that needed to be an ATC is highly competitive.

Another possible option for Congress is to provide special funding for the

purposes of hiring and training the next generation of ATC specialists. FY2005

appropriations included $9.5 million for this purpose. For FY2006, the House bill

included almost $25 million to increase the FAA workforce by 595 air traffic

controllers. However, the final appropriations act (P.L. 109-115) did not include

specific reference to this amount. Faced with budget constraints and rising

operational costs, it is uncertain how the FAA will allocate funding to address the

continuing need for succession planning, hiring, and training of air traffic controllers

in the near term.

If controller shortages persist, there may be a need to increase overtime and

perhaps impose mandatory overtime for controller staff. Such practices may impact

safety because it may contribute to controller fatigue. Additionally, a 2002 GAO

survey found that use of mandatory overtime may result in more controllers opting

to retire earlier.24 Thirty three percent of controllers indicated they would retire

earlier if required to work additional overtime hours.

24

U.S. General Accounting Office. Air Traffic Control: FAA Needs to Better Prepare for

Impending Wave of Controller Attrition. June 2002, GAO-02-591.

CRS-23

A more controversial option that has been proposed in various forms over the

years is the partial or complete commercialization or privatization25 of the air traffic

control system, including ATC job functions. The FAA already uses commercial

contractors to run about 218 non-radar towers throughout the country, including

several airports that handle commercial operations. Proponents for privatizing the

entire air traffic control system also note that many foreign countries including

Canada, Great Britain, much of mainland Europe, and Australia operate their air

traffic control systems under various forms of privatization. Besides addressing

controller staffing issues, commercializing or privatizing the ATC is viewed by some

as a means to potentially overcome perceived management deficiencies that have

historically plagued FAA’s handling of ATC systems acquisitions.

Critics of privatizing the ATC system fear that it could erode safety, although

a recent DOT Inspector General’s audit of the FAA’s contract tower program found

no identifiable difference in operational error rates between contract towers and

FAA-run towers.26 Language protecting the FAA air traffic control system from

further privatization, except for maintaining and possibly expanding the contract

tower program, was ultimately dropped from the FAA reauthorization bill (Vision

100; P.L. 108-176). As a concession for removing this language, the FAA had

agreed to a moratorium on any further plans for privatization or commercialization

of ATC functions during FY2004 which has now expired. Given the pending

controller staffing shortages faced by the FAA, debate over ATC privatization may

be revisited. However, any plan to commercialize or privatize operations at busy

towers or any en route facilities is likely to be highly controversial.

FAA’s Organizational Culture

Historically, poor planning, management, and oversight of major ATC-related

acquisitions by the FAA has been blamed for cost overruns, schedule slips, and

performance shortfalls of major systems designed to enhance the capacity of the

national airspace system. FAA’s poor track record in systems development has led

many observers to speculate that the FAA’s own organizational culture is the root

cause of difficulties in meeting the challenges of enhancing aviation system capacity

to keep pace with growth in air traffic operations. The GAO noted that over the

years, inadequate management controls and human capital issues at the FAA have

contributed to consistent cost overruns, schedule delays, and performance shortfalls

of major air traffic control and management projects.27 Similarly, the DOT Inspector

25

ATC commercialization, as used in this paper, refers to the outsourcing of some or all

ATC functions to commercial vendors, whereas privatization encompasses both outsourcing

of ATC functions and possible implementation of user fees or other revenue-generating

mechanisms to fund ATC services. In recent congressional debate, the term privatization

has been used to refer to legislative proposals calling for protections against privatization

that would limit both commercialization and privatization of ATC functions.

26

Department of Transportation, Office of Inspector General. Safety, Cost, and

Operational Metrics of the Federal Aviation Administration’s Visual Flight Rule Towers.

AV-2003-057. September 4, 2003.

27

U. S. General Accounting Office. Air Traffic Control: FAA’s Modernization Efforts —

(continued...)

CRS-24

General found that the FAA exhibited lax oversight of contracts and continued to

operate with an ineffective vertical, hierarchical management structure. The DOT

Inspector General also found that management inefficiencies persisted on major

programs despite the fact that, in 1995, the FAA was statutorily exempted from many

of the federal procurement regulations it had argued were hindering modernization

efforts.28

The response of Congress to these concerns was twofold. First, AIR-21 (P.L.

106-181) mandated the creation of a Chief Operating Officer (COO) position within

the FAA to oversee the strategic plans, operations, and budget of the air traffic

control system. More recently, in Vision 100 (P.L. 108-176), Congress set forth a

framework for the creation of a joint planning and development office to establish

the long range national plan for the national airspace system and oversee the

implementation of that plan. The Bush administration has responded to these

mandates with the establishment of the Air Traffic Organization (ATO) within the

FAA headed by the COO, and the creation of a multi-agency Joint Planning and

Development Office (JPDO) headed by the FAA. While these steps formally

restructure the FAA in significant ways, an important issue is whether these

organizational changes will lead to meaningful changes within the FAA’s

organizational culture and enable the FAA to better meet the challenges it faces in

expanding the capacity of the national airspace system.

Air Traffic Organization. The first COO of the ATO was finally hired and

the ATO was formally established on February 8, 2004, almost four years after it was

mandated under AIR-21. The new COO, Russell Chew, has indicated that the

primary emphasis of the reorganization that has taken place within FAA to establish

the ATO is designed to integrate acquisition and operations functions to make sure

that major systems acquisitions are better tied to operational service needs and

operational cost considerations.29 The ATO is comprised of 10 service units, each

run by a vice president that reports to the COO. The 10 service units are:

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Safety

Communications

Operations Planning

Finance

Acquisition and Business Services

En Route and Oceanic Services

Terminal Services

Flight Services

System Operations Services

Technical Operations Services

27

(...continued)

Past, Present, and Future. Statement of Gerald L. Dillingham, Director, Physical

Infrastructure Issues Before the Subcommittee on Aviation, Committee on Transportation

and Infrastructure, House of Representatives. October 30, 2003 (GAO-04-227T).

28

Department of Transportation, Office of Inspector General. Top Ten Management Issues.

Report PT-2001-017, January 18, 2001.

29

“Russ Chew 101.” Aviation Week & Space Technology, August 16, 2004, 46-48.

CRS-25

In addition to its internal safety office, the FAA created the Air Traffic Safety

Oversight Service within its Office of Regulation and Certification, which is

responsible for oversight and coordination of system safety functions within FAA,

including the ATO.

Since the ATO has existed for less than one year, it is too early to fully assess

its effectiveness. One indicator of the ATO’s success is how well it is meeting its

own performance objectives. In this regard, the results have thus far been mixed.

The ATO has thus far failed to meet its goals for on-time arrivals and arrival

efficiency.30 However, the ATO has generally met its criterion to have air traffic

equipment operationally available 99% of the time. However, a high profile ATC

equipment outage in the busy southern California airspace in September 2004 due to

maintenance errors highlighted the criticality of these systems and the need for

extremely high reliability and available backup capabilities. With regard to safety,

while it appears that some progress has been made to reduce the number of runway

incursions, the National Transportation Safety Board (NTSB) has recently questioned

the completeness and accuracy of the FAA’s statistics on runway incursion incidents.

Additionally, operational errors remain at higher than acceptable levels as defined in

FAA’s performance goals. The FAA’s ability to meet performance objectives and

the effectiveness of the ATO organization is likely to be an issue of continued

interest for Congress as the ATO matures and more fully engages in addressing the

operational challenges created by growth in aviation operations.

Joint Planning and Development Office. Another initiative to revamp

FAA’s organizational culture and approach to systems planning and acquisition is the

creation of the Next Generation Air Transportation System Joint Planning and

Development Office (JPDO). The JPDO was established under the most recent FAA

reauthorization bill, Vision 100 (P.L. 108-176), and is charged with the task of

establishing and executing the national plan for the next generation air transportation

system (NGATS). Whereas the ATO is focused on the day-to-day operational

aspects of running the existing national airspace system and implementing the short

term capacity enhancement objectives defined in the OEP, the JPDO’s focus is on

long range planning to meet the anticipated capacity requirements of 2025.

Under a provision in Vision 100 (P.L. 108-176), the JPDO was required to

submit its NGATS integrated plan to Congress by December 2004. That plan was

unveiled by the JPDO on December 12, 2004.31 Under the provisions of Vision 100,

the JPDO is now responsible for overseeing the execution of the plan and

coordinating research and development and implementation efforts among

government agencies and industry to achieve the goals set forth in the plan. In

developing and executing the NGATS integrated plan, FAA is required to work in

conjunction with relevant programs in the Department of Defense, the National

30

Arrival efficiency is a measure of how well the actual arrival rate compares to the lesser

of the scheduled arrival demand or the established arrival rate for an airport.

31

Next Generation Air Transportation System Joint Planning and Development Office. Next

Generation Air Transportation System Integrated Plan. December 12, 2004: Washington,

DC.

CRS-26

Aeronautics and Space Administration, the Department of Commerce, and the

Department of Homeland Security. The goals of implementing the NGATS plan

include:

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Improving the safety, security, efficiency, quality, and affordability

of aviation;

Exploiting emerging ground-based and space-based

communications, navigation, and surveillance technologies;

Integrating data streams from multiple agencies and sources to

enable situational awareness and seamless global operations for civil

aviation, homeland security, and national security;

Leveraging investments in civil aviation, homeland security, and

national security and build upon current air traffic management and

infrastructure initiatives to meet system performance requirements

Accommodating and encouraging substantial growth in domestic

and international transportation and anticipating and accommodating

continued technological growth;

Accommodating a wide range of aircraft operations, including

airlines, air taxis, helicopters, general aviation, and unmanned aerial

vehicles; and

Designing airport approach and departure flight paths to reduce

noise and emissions exposure of affected communities.

The NGATS integrated plan provides a top-level roadmap identifying core

objectives and strategies for transforming the national airspace system to meet future

capacity needs. The integrated plan outlines several goals for the NGATS including:

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Establishing innovative airport planning and management;

Establishing a cost effective aviation security system without

limiting mobility or civil liberties;

Establishing an agile air traffic system;

Establishing user specific situational awareness within the air traffic

system;

Establishing a comprehensive, proactive safety management

approach;

Developing environmentally friendly and sustainable air traffic

technology;

Developing a system-wide capability to reduce the impact of

weather; and

Harmonizing equipment and operations internationally.32

JPDO director, Charles Keegan, has indicated that the NGATS plan will rely

heavily on increasing automation of air traffic functions and reducing system costs.

However, the initial report is reported to contain few details on what technologies,

operational changes, and integration schemes will be implemented to achieve these

32

David Hughes. “The ‘Silent’ Crisis.” Aviation Week & Space Technology, October 25,

2004, 72-75.

CRS-27

objectives.33 Providing too many details, however, could place artificial constraints

on the plan by settling on specific technologies that may become obsolete before they

are implemented. It is difficult to foresee how technology may evolve over the next

ten years or what breakthrough technologies with application to air traffic

management and control might emerge. Based on this, the apparent strategy the

JPDO seems to be adopting is a rather broad framework, or architecture, for how

emerging and future technologies may be integrated into the NGATS system.

However, in adopting such a strategy there may be a risk of being too vague and not

providing sufficient detail to be useful. Congressional oversight may specifically

focus on whether the plan contains sufficient detail to measure progress over time

toward achieving the end goal of increased capacity and efficiency in the national

airspace system as well as whether the plan creates an organizational climate and

facilitates partnerships with other government agencies and the aerospace industry

to foster cooperative and collaborative work toward achieving this vision.

Cost Overruns

The FAA’s original plan to modernize the air traffic control system, began in

the early 1980s and was estimated to be completed by the early 1990s at a projected

cost of $12 billion. A central element of that modernization effort, the advanced

automation system (AAS) was ultimately scrapped in large part after large cost

overruns, schedule delays, and failures to deliver promised capabilities and

performance. According to the GAO, since then FAA’s cost estimates have

mushroomed and schedules have continued to slip. Over $35 billion have been

spent so far on modernizing the national airspace system and the FAA estimates it

will need an additional $16 billion through 2007 to complete key projects.34

In fairness to the FAA, it is important to point out that many of the system

modernization projects included in its current efforts to increase system capacity

were not even conceived of in the early 1980s. The efforts of the early 1980s that

extended into the 1990s were largely aimed at improving the existing en route and

terminal radar networks by upgrading hardware and software and providing

controllers with improved workstations and consoles and rudimentary automation

tools. These efforts focused largely on air traffic communications and surveillance,

and largely did not address enhancement to navigation capabilities. The global

positioning system’s (GPS) network of navigation satellites did not exist when the

program was initiated; therefore, programs like WAAS and free flight were not

initially calculated into cost projections. GPS and GPS-related technologies, the

enabling technologies allowing revolutionary new navigational concepts like free

flight to be implemented, have only been considered as part of FAA’s air traffic

control modernization plans for the past 10-years or so. In essence, looking broadly

at the current costs to enhance FAA facilities and equipment compared to past cost

estimates is not a fair comparison. However, what is clear is that, on a program by

program basis, FAA spending on ATC modernization efforts has been riddled with

cost overruns and schedule slips.

33

Ibid.

34

U.S. General Accounting Office. Air Traffic Control: FAA’s Modernization Efforts.

CRS-28

The FAA’s historic cost overruns and schedule slips in its AAS program

throughout the 1980s and into the 1990s, well documented in GAO reports and DOT

IG audits, gave the FAA a reputation as an ineffective manager of major systems

acquisitions. The GAO has routinely found, and continues to identify inadequate

cost controls, cost estimating, and cost accounting within FAA as a significant

impediment to effective management of large scale acquisition programs. Also, the

FAA still does not have a sufficiently detailed blueprint tying its major acquisition

programs to modernization objectives for the air traffic control system, and does not

adequately link these programs to both near term and long-range budget projections.35

One of the principal objectives of the new ATO and JPTO is to address these

concerns. Time will tell if these new organizations are effective in meeting this

objective, and it is likely that the work of these organizations will be a subject of

considerable congressional interest over the next several years.

Russell Chew, the COO of the ATO, is well aware of the challenge faced by his

organization. The ATO is facing a $5 billion shortfall in operations and a $3.2

billion shortfall in the airport and airways trust fund if operations and capital

improvements continue to follow a “business as usual” approach.36 Chew believes

that the answer to the problem — given no foreseeable increase in aviation trust fund

tax yield and a decreased reliance on general fund coffers to make up for trust fund

shortfalls — is to focus on reducing unit costs for air traffic services. Chew’s

initiatives to reduce costs include

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Streamlining management and reducing overhead staff not directly

involved in providing service;

Improving productivity;

Improving training efficiency;

Improving infrastructure efficiency;

Developing cost-saving cooperative efforts with the airline industry;

Managing costs of growing system complexity effectively;

Revamping telecommunications infrastructure;

Using competitive sourcing to reduce flight service station operating

costs; and

Improving the management and oversight of time off, sick leave, and

overtime.

The ATO faces major challenges to find savings in these areas to reduce overall

air traffic service costs by 21%, which is what it projects the deficit would be over

the next five years if they maintain the status quo. Only one of these efforts —

revamping telecommunications infrastructure — is underway, and that is only

expected to net a savings of about 1% annually. Chew noted that hard choices must

35

36

Ibid.

David Hughes. “Affordable ATC Ops.”

November 8, 2004, p. 46.

Aviation Week and Space Technology.

CRS-29

be made in the near future to achieve sustainable, cost-efficient air traffic services.37

The decisions made by the ATO in meeting these challenges are likely to be a key

topic for congressional oversight of the FAA.

Impact of Under-capacity on Flight Operations

To understand the need for increased capacity, it is important to examine the

effects of under-capacity on flight operations. Examining past deficiencies in

meeting aviation demand can help identify capacity needs on both a systemwide and

an airport-by-airport level of analysis. Examination of these capacity strained periods

can also provide useful data for modeling the potential benefits of capacityenhancement proposals.

Presently, the effect of capacity constraints are beginning to be felt once again

as demand for air travel returns to pre-September 11, 2001 levels. Throughout the

summer of 2004, increased demand brought with it increased delays, but so far,

system-wide operations and delays have not reached the level they were at during the

summer of 2000.

The Summer of 2000

During the summer of 2000, record setting demand for air travel, a long bout

with thunderstorms — particularly in the busy northeast corridor and at major hubs

like Dallas-Fort Worth, Chicago, and Atlanta — and aircraft maintenance difficulties

conspired to produce long delays and cancelled flights that wreaked havoc on many

travelers’ plans. This difficult time for travelers was followed by even more acute

delays during the 2000 holiday season in December. During these periods, air

travelers experienced the worst delays in U.S. aviation history and delays frequently

exceeded acceptable levels.38 Following this period, the U.S. economy entered a

downturn that reduced demand for air travel. Meanwhile, the FAA was busy

implementing near term solutions to avoid a repeat of the summer of 2000. The net

result was less traffic volume and significantly fewer and shorter delays in the

summer of 2001. Since then, airline travel significantly declined in the aftermath of

the September 11, 2001 terrorist attacks and, as might be expected, delays have been

significantly less in the past three years. Recent statistics released by the Department

of Transportation’s Bureau of Transportation Statistics indicate that delays are on the

rise, although not to the level seen in the summer of 2000 (See Figures 7 & 8).

While the decrease in demand for air travel from 2001 to 2004, in essence, bought

the FAA additional time to study and implement near term solutions to alleviate

congestion and delay, the effectiveness of these mitigation strategies remains largely

undetermined and over the past two years key delay statistics have been steadily

37

38

Ibid.

In the OEP, the FAA adopted a standard of maintaining an average delay of 14 minutes

or less. Based on this standard, average delays in excess of 14 minutes are described as

exceeding acceptable levels in this report.

CRS-30

rising, a possible indicator of increasing strain on system capacity. As traffic volume

increases and surpasses pre-September 11, 2001, levels over the next few years, the

near term mitigation strategies to alleviate congestion and delay will receive the first

real tests of their effectiveness.

Figure 7. Average Delay (1/1998 — 11/2005)

Average Delay (Minutes)

Departures

Arrivals

Solid line: 12-month moving average

Year

Source: Bureau of Transportation Statistics.

Percent Delayed (>15 Minutes)

Figure 8. Percent of Flights Delayed (1/1998 — 11/2005)

Departures

Arrivals

Solid line: 12-month moving average

Year

Source: Bureau of Transportation Statistics.

CRS-31

Some Possible Delay Remedies

In examining the delay data in Figures 7 & 8, it is notable that while the

monthly average departure delay has typically been greater than monthly average

arrival delay, a greater proportion of arrivals are delayed more than 15 minutes

compared to departures.39 Thus, from a operational standpoint, airborne delays that

impact arrival times, while less frequent than delays affecting departure times, are

more likely to be longer in duration. Given that airborne delays are costly to airlines

in terms of fuel costs, increased wear and tear on the engines, and so on, specific

operational strategies to reduce these airborne delays would be particularly

advantageous to airlines and other aircraft operators. FAA has been working with

the airlines to take such steps to reduce airborne delays. Some examples include:

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Using ground holds to delay departures in order to better space

arrivals at destination airports;

Using decision aids to meter the flow of arrivals into busy airports;

and

Creating “express lanes” into and out of busy airports by holding

traffic at satellite and reliever airports during peak travel hours.

It appears that these efforts were somewhat effective in staving off a repeat of

delays such as those experienced in the summer of 2000, during the peak travel

months of 2004 and 2005. However, the upward trend in delay statistics, especially

arrival delays, during the peak summer and holiday travel seasons of 2004 and 2005,

could be a forewarning that chronic delay conditions may return to the aviation

system as operations surge past pre-September 11, 2001, levels over the next several

years.

The Relationship Between Capacity and Delay

While the FAA continues to implement stopgap measures to mitigate delay in

the current national airspace system, most observers recognize that the long term

solutions to alleviating congestion and delay should address the underlying capacity

constraints. Since delay is a key symptom of strain on system capacity, delay can be

mitigated to some extent by investing in capacity-enhancing infrastructure and

technologies. However, in practice, policymakers and system planners must balance

a tradeoff between meeting demand for aviation services while maintaining delays

within acceptable levels. Given that growth in aviation operations may easily

outpace capacity enhancement of the national airspace system for the foreseeable

future, policymakers will likely face tough choices in meeting demand without

increasing delay.

The FAA’s OEP (Version 6.0) projects a 27% overall capacity enhancement

by 2013. However, this capacity enhancement assumes that an average system delay

of 14 minutes is acceptable and does not seek to reduce this level of delay in its

projections of future system capability. Rather, the FAA intends to increase capacity

at what it has set as a threshold acceptable level of delay — the typical delays flyers

39

Based on Bureau of Transportation Statistics delay data.

CRS-32

have grown accustomed to, but not the extent of delays experienced in the summer

of 2000. The potential danger of this strategy is that with an emphasis on enhancing

capacity to meet growth in demand, delay may increase significantly in a capacityconstrained system, especially if capacity enhancement efforts fall behind schedule

or fail to fully meet expectations.

Figure 9 shows conceptually the tradeoff that exists between capacity and delay.

In essence, these two metrics comprise elements that compete for system capability.

In reality, the situation is much more complex since the relationship between capacity

and delay is influenced significantly by external factors, such as weather and airline

scheduling practices, that are either uncontrollable or not controlled directly within

the system. Certainly, the relationship between capacity and delay and the influence

of both system variables and external factors on these two metrics is very complex.

While the tradeoff relationship between capacity and delay may be difficult to

quantify or predict, the effect is relatively easy to conceptualize. Working from a

baseline capacity (CB), enhanced system capabilities can be projected to enhance

capacity assuming a fixed level of delay (CFD). The FAA chose to conceptualize

capacity enhancement in this manner, selecting a fixed systemwide acceptable level

of delay of 14 minutes — a figure never exceeded before the infamous summer of

2000 — as its target.

Figure 9. The Tradeoff Between Expanding Capacity and

Mitigating Delay

0

1

2

3

Enhanced System Capability

Average Delay (minutes)

4

5

6

Baseline

7

8

9

10

11

12

13

Maximum Acceptable Delay

14

15

0

CB

CRD

CFD

CID

Capacity (Operations/Hour)

Where,

CB is baseline capacity (that is, current available capacity);

CRD is future capacity with a reduced delay;

CFD is future capacity assuming a fixed delay; and

CID is future capacity assuming an increase in delay.

Source: Bureau of Transportation Statistics average delay data and FAA OEP (Version

6.0) fixed level of delay for assessing effective capacity.

CRS-33

While the FAA’s objective is to meet growth in demand while maintaining

delays at 14 minutes or less, consumer complaints tend to focus on system delays

rather than available capacity. Therefore, reducing delay might be a reasonable

objective for enhancing system capability. In Figure 9, it can be seen that, at least

conceptually, capacity can be traded for a reduction in delay within the bounds of

system capability. So, the capacity enhancement achievable with a reduced delay

(CRD) is not as large as the capacity reduction with a fixed delay (CFD). However,

delays could potentially be reduced along with a less significant gain in capacity

(CRD) if reducing delay was targeted as an objective of system enhancement.

Conversely, capacity could grow larger, although not as significantly due to other

constraining factors, if delays were allowed to increase. That is, the conceptual

increase in capacity with increased delay (CID) is greater than the capacity

enhancement with a fixed delay (CFD).

As the capability of the national airspace system expands, it is largely a policy

decision whether the enhanced capability will be used primarily for increasing

capacity or for decreasing delay. However, the FAA’s forecast that growth is

expected to meet or exceed planned capacity improvements provides a reasonable

justification for adopting a policy of projecting capacity expansion while attempting

to maintain a fixed level of delay. Capacity is projected to, at best, parallel expected

growth through 2010. Therefore, essentially all of the projected enhancements to be

engineered into the national airspace system by that time will be needed to meet the

forecast growth in aviation operations. Therefore, if demand is to be met,

enhancements are not likely to be available for mitigating delay. Furthermore,

system enhancement efforts are likely to have a greater impact on increasing capacity

rather than decreasing existing delay, given that delay is constrained to a greater

extent by external factors such as weather and airline scheduling practices that are

more difficult to control. Also, given the complexity of tradeoffs between capacity

and delay, using a fixed level of delay in projecting future effective capacity

simplifies the comparison to baseline capacity levels. An alternative strategy, that

would involve core conceptual changes in policy, would value system efficiency over

capacity and target reducing delays. Such an approach may involve various marketbased strategies, discussed later in this report, to reduce demand characteristics for

aviation operations in addition to system enhancements targeting delay reduction.

While a more efficient national airspace system may improve the satisfaction of

many consumers, it is likely to increase associated costs by limiting the supply of

aviation services. Therefore, such a shift in policy regarding the objectives for

modernizing the national airspace system could be contentious.

Impact of Congestion on Aviation Safety

As demand for air transportation continues to grow, increasing flight operations

may introduce additional risks to aviation safety that may need to be addressed if the

system is to maintain or improve upon its current level of safety while at the same

time addressing capacity needs. The FAA’s ATO has identified two key indicators

of safety in its performance-based plan: runway incursions and air traffic controller

operational errors.

CRS-34

Runway Incursions

As traffic density at airports increases, so does the probability that an aircraft or

ground vehicle will enter on to an active runway when an aircraft is taking off or

landing unless steps are taken to effectively reduce the likelihood of such

occurrences. The FAA refers to these breaches of runway safety that occur at

towered airports as runway incursions.40 Runway incursions pose a significant safety

risk because they are the manifestations of human errors and pre-existing conditions

that may well have led to a runway collision.

The potentially deadly consequences of a runway collision were highlighted

most recently on October 8, 2001 when a Cessna business jet strayed on to the active

runway in foggy conditions and was struck by a departing airliner at Milan, Italy’s

Linate Airport killing 118 people and injuring 4.41 A year earlier, a Singapore

Airlines 747 bound for Los Angeles mistakenly attempted to take off from Taiwan’s

Chiang Kai Shek International Airport using a partially closed runway at night during

a typhoon. The airplane collided with construction equipment killing 83 of the 179

on board.42 The world’s deadliest aircraft accident (583 fatalities), the 1977 collision

between two Boeing 747 aircraft on the Island of Tenerife, was also the result of a

runway incursion during low visibility conditions.43

The United States has not been immune to such disasters. Since 1990, there

have been four runway collisions in the United States involving large commercial

airliners. The deadliest runway collision in the U.S. occurred at Los Angeles

International Airport (LAX) on the night of February 1, 1991. A USAir Boeing 737

was cleared to land on a runway occupied by a commuter flight that was instructed

to line up on the runway and await takeoff clearance. The National Transportation

Safety Board (NTSB) determined that the accident was attributable to shortcomings

in LAX’s air traffic control management, procedures, and oversight, which ultimately

led to the failure of the tower controller to maintain appropriate situational

40

The FAA defines a runway incursion as any occurrence in the airport runway environment

involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard

or results in a loss of required separation with an aircraft taking off, intending to take off,

landing, or intending to land (See FAA Office of Runway Safety. Runway Safety Report:

Runway Incursion Trends at Towered Airports in the United States (FY1999-FY2002). July

2003).

41

Agenzia Nazionale per la Sicurezza del Volo (Italy). Milano Linate, ground collision

between Boeing MD-87, registration SE-DMA and Cessna 525-A, registration D-IEVX.

January 20, 2004.

42

Aviation Safety Council (Taiwan, Republic of China). Crashed on a Partially Closed

Runway During Takeoff — Singapore Airlines Flight 006 — Boeing 747-400, 9V-SPK —

CKS Airport, Taoyuan, Taiwan, October 31, 2000. Aircraft Accident Report ASC-AAR-0204-001.

43

Subsecretaria de Aviacion Civil (Spain). KLM, B-747, PH-BUF and Pan-Am B-747,

N736 — Collision at Tenerife Airport, Spain on 27 March 1977. Madrid, Spain.

CRS-35

awareness.44 Another notable runway collision occurred in the U.S. on November

22, 1994 when a TWA DC-9 collided with a twin-engine Cessna at St. Louis

International Airport (STL), Missouri. Similar to the recent Milan crash, the NTSB

found that the Cessna pilot had mistakenly taxied past the assigned runway and into

the DC-9’s path in foggy conditions. The NTSB further concluded that airport

surface monitoring equipment could likely have prevented the collision.

Since FY1999, the rate of runway incursions at the nation’s 35 busiest airports

has remained relatively constant, slightly above 5 incursions per million flight

operations.45 Overall, the rate of incursions for commercial operations has averaged

slightly more than 5.5 incursions per million flight operations. While the overall rate

of runway incursions appears to be relatively constant since 1999, the FAA has noted

that the severity of incursions declined during that period. That is, a decline in the

most serious types of incursions — those classified by the FAA as having a

significant or extreme collision potential (Category A and B incursions) — was

observed, whereas the rates of less severe incursion incidents (Category C and D

incursions) has remained relatively unchanged (see Figure 10).

Figure 10, Runway Incursion Rate

5.9

4.8

6.2

5.2

5.3

5.2

Source: FAA Runway Safety Report, July 2003, August 2004, & August 2005.

While the FAA concluded that this trend demonstrates progress in mitigating

the severity of runway incursions, such a conclusion may be premature. Given the

low rate of these events (about 1 in every 3 to 5 million operations), it is difficult to

44

National Transportation Safety Board. Runway collision of US Air Flight 1493, Boeing

737 and Skywest flight 5569 Fairchild Metroliner, Los Angeles, California, February 1,

1991 (AAR-91-08).

45

See FAA Runway Safety Reports (July 2003, August 2004, and August 2005).

CRS-36

say for sure whether this reduction in incursion rate is meaningful and even more

difficult to attribute it to specific actions taken to reduce the rate and severity of

incursions. Furthermore, the reduction in severity levels observed between 2001 and

2002, has appeared to flatten. This may indicate that the effects of currently

implemented mitigation strategies have already been largely realized. If this is the

case, then more may need to be done to keep the overall numbers of Category A and

B incursions to a minimum. This is because, even if the severe incursion rate is held

constant, increasing number of operations will bring with them likely increases in the

number of severe incursions. While more data is needed to draw meaningful

conclusions regarding the reduction in risk of runway incursions, these trends are at

least promising and the FAA is continuing its efforts to implement operational and

technological approaches to further reduce runway incursions.

Of the OEP-35 airports, 7 had 15 or more incursions over the four year period

from 2000-2003. These airports were: Chicago-O’Hare (ORD); Dallas-Fort Worth

(DFW); Los Angeles International (LAX); Phoenix Sky Harbor (PHX); Boston

Logan (BOS); Saint Louis (STL); and San Francisco International (SFO). Traffic

density was certainly a major contributing factor in the number of runway incursions

experienced at an airport. Four of these 7 airports were among the top 5 busiest

airports in the United States. The FAA recognizes that traffic volume is a major

factor in runway incursions since increases in operations increase the number of

opportunities for error. However, the FAA found that annual fluctuations in traffic

volume did not have predictable effects on runway incursions rates. Thus, traffic

volume appears to interact with airport-specific characteristics to affect the likelihood

of runway incursions in complex ways that are not yet fully understood.

The highest number of runway incursions (34), and the largest number of

Category A & B incursions (12) over the 2000-2003 period for the OEP-35 airports

was observed at LAX, which ranks fourth overall in number of operations and has

a complex taxiway layout. However, LAX had no Category A & B incursions in

2003 suggesting that, while they have been unable to reduce the annual number of

incursions at that airport, strategies to mitigate the severity of incursion incidents

appear to be working there. Efforts to date have primarily focused on outreach to

increase pilot runway safety awareness, improved signs, pavement markings, and

lighting, and procedural modification to improve operational safety.

Besides high traffic density, the attributes that those airports experiencing higher

numbers of runway incursions appear to share include complex taxiway and runway

layouts; and complex taxi procedures. Some, but not all, of these airports have

intersecting runways which also present opportunities for runway incursions to occur.

The runway incursion risk of intersecting runways could have implications for

capacity-enhancing operational procedures such as land and hold short operations

(LASHO) in which pilots of landing aircraft are required to stop before reaching a

crossing runway so that simultaneous operations can be conducted on both runways.

Clearly, other airports share these attributes as well and procedures such as LASHO

have been used safely for many years. Therefore, the specific factors that make an

airport more vulnerable to runway incursions are not yet completely clear. How

airport-specific factors such as infrastructure, procedures, operations, and

environment interact with traffic density to define the runway incursion risk for a

specific airport is not fully understood and continues to be scrutinized by the FAA

CRS-37

and others to identify the influence of these various factors on runway incursion

risk.46

The leading direct cause of runway incursions was pilot deviations, which

account for about 53% of incursions involving commercial aircraft. Controller errors

and deviations account for about 29% of runway incursions among incursions

involving commercial aircraft and incursions occurring at the OEP-35 airports.

Deviations by vehicles and pedestrians operating in the air operations area comprise

the remaining runway incursions. Consequently, mitigation measures to reduce

runway incursions are likely to have the greatest benefit if they can reduce the

number of pilot deviations during surface movement. However, FAA’s efforts to

date in terms of high cost technology options — including ground radar (Airport

Surface Detection Equipment (ASDE) and the Airport Movement Area Safety

System (AMASS) — are primarily focused on improving air traffic controller

situation awareness regarding traffic position and the potential for incursions.

In 2001, the NTSB evaluated the Airport Movement Area Safety System

(AMASS) and determined that it was not capable of providing sufficient warning to

prevent runway collisions in all instances and, as currently implemented, provides no

capability to issue warnings directly to pilots and other vehicle operators.47 In

essence, the AMASS system inserts controllers into the decision cycle, thereby

increasing the time needed for pilots to take evasive action to prevent a collision.

Providing traffic information and alerting directly to pilots, as opposed to only

alerting controllers, would be preferable in this regard. But, this is not what the

NTSB’s original recommendation sought. Rather the NTSB specifically asked the

FAA to develop a system analogous to cockpit traffic collision avoidance systems

(TCAS) to alert controllers to pending runway incursions.48 However, TCAS

provides alerts and conflict resolutions directly to pilots.

The NTSB assessment went on to conclude that FAA’s efforts to curtail runway

incursions largely through technological approaches aimed at improving air traffic

controller situational awareness was an incomplete solution, and specifically called

for specific actions to address recommended changes in operational procedures at

airports. The NTSB’s recommendations urged the FAA to install ground movement

safety systems at all airports with passenger service that provide a direct warning

capability to pilots, and demonstrate through computer simulations or other means

that the system will, in fact, prevent runway incursions. The recommendations also

included numerous suggested changes to operational procedures to: increase pilot and

controller situation awareness and resolve ambiguities regarding runway crossing

clearances; eliminate the practice of positioning an aircraft on a runway to await

takeoff at night and in poor weather; modify phraseology of airport movement

46

FAA Office of Runway Safety. Runway Safety Report. (July 2003 and August 2004).

47

Carol J. Carmody. Testimony before the Committee on Transportation and Infrastructure,

House of Representatives Regarding Runway Incursions, June 26, 2001. Washington, DC:

National Transportation Safety Board.

48

National Transportation Safety Board. Runway collision of Eastern Airlines Boeing 727,

flight 111 and Epps Air Service Beechcraft King Air A1000, Atlanta Hartsfield International

Airport, Atlanta, Georgia, January 18, 1990 (NTSB/AAR-91/03).

CRS-38

instructions to be consistent with international standards; and provide controllers

with guidance on appropriate phraseology and speaking rates, especially when

communicating with foreign flight crews.49

The FAA continues to address many of these procedural changes to enhance

runway safety. However, the NTSB has expressed continued frustration with the

FAA’s progress. At a recent meeting, the NTSB questioned the completeness of the

FAA’s runway incursion incident reporting and cast doubt on FAA’s claims that the

incursion rate is declining.50 Most observers agree that there is no single solution to

mitigating runway incursions and continued investment in airport design, procedural

modifications, pilot and controller training, and technology is needed to reduce the

risk of runway accidents. Several mitigation strategies to reduce the potential for

runway incursions are currently being implemented or are under study by the FAA

and NASA. Mitigation strategies to reduce the risk of runway incursions can be

placed into six general categories, as shown in Table 1. These various strategies are

mainly aimed at improving pilot and controller situational awareness regarding:

aircraft position relative to other aircraft and ground vehicles; aircraft and vehicle

position relative to assigned taxi routes and active runways; and flight crew and

vehicle operator understanding of taxi instructions and runway clearances. Other

solutions seek to provide controllers and pilots with alerting and conflict resolution

capabilities to predict and circumvent impending runway incursions or reduce the

severity of incursions by reducing the risk that such an event could result in a

collision.

Table 1. Mitigation Strategies to Prevent Runway Incursions and

Reduce Their Severity

Mitigation Strategy

Examples

Markings, Signs, and Lighting

High Contrast Taxiway Markings and

Hold Short Lines;

Improved Visibility and Positioning of

Signs; and

Runway Status Lights

Increasing Pilot Positional Awareness

Cockpit Moving Map Displays; Airport

Position Transmitting Devices; and

Auditory Advisories and Audible

Warnings

49

National Transportation Safety Board. Safety Recommendations A-00-66 through A-0071.

50

National Transportation Safety Board. NTSB calls for federal action to adopt “most

wanted” safety improvements. Press Release SB-04-33, November 9, 2004.

CRS-39

Increasing Pilot and ATC Traffic

Awareness

Ground Surveillance Radar (e.g., Airport

Surface Detection Equipment - Model X

(ASDE-X)); and Cockpit Traffic

Information Displays (e.g.,

Traffic Information Service (TIS),

Cockpit Display of Traffic Information

(CDTI))

Procedures and Training

Ramp worker training;

Educational materials to flight crews and

operators of ground vehicles and

equipment;

Modifying and standardizing taxi routes;

and

Modifying ATC phraseology

Warning Devices and Conflict Resolution

Advisory Systems

Airport Movement Area Safety System

(AMASS); and

ASDE-X with conflict detection alerting

capabilities

Airport Redesign/Reconfiguration

Perimeter taxiway construction;

Eliminating or minimizing intersections

where taxiways cross runways

Loss of Separation and Near Mid-Air Collisions

As runway incursions are indicators of safety risk associated with ground

operations, breaches of required airborne separation between aircraft are indicators

of safety risk during flight. These loss of separation incidents are a safety concern

because they point to system failures and errors that could lead to a midair collision.

A loss of separation caused by an air traffic control error is termed an operational

error. Operational errors, like runway incursion, are placed into one of four

categories (A, B, C & D) based on severity. Operational errors are reviewed and

scored using a point system that considers factors such as: the vertical and horizontal

separation between aircraft; whether the aircraft were on converging or diverging

flight paths; the closure rate between aircraft; and whether ATC took corrective

actions or TCAS (Traffic Collision Avoidance System) resolution advisories were

issued.51 The severity is then categorized as high, moderate, or low. Under recent

changes by the FAA, these three levels of severity are now grouped into four

categories, in the following manner:

!

!

51

Category A: All high severity incidents

Category B: All moderate severity incidents where ATC fails to

take corrective action (uncontrolled)

Federal Aviation Administration. Air Traffic Quality Assurance. Order 7210.56C,

August 15, 2002.

CRS-40

!

!

Category C: All moderate severity incidents where ATC takes

appropriate corrective action (controlled); and

Category D: All low severity incidents

There is growing concern over operational errors as annual operational error

rates — expressed as the number of incidents per million flight operations — have

been on the rise over the past five years and are up 35% compared to the previous

five year period (see Figure 11). Furthermore, the severity of these operational

errors has been regarded as being too high. Specifically, the DOT Inspector General

reviewed severity ratings for 13 months of operational error data collected from May,

2001through May 2002 and found that 78 percent were classified as moderate

severity, and 6% were classified as high severity, while only 22% were classified as

low severity.52 The DOT Inspector General’s report concluded that much work needs

to be done to reduce the severity of operational errors so that the large majority are

low severity events.

Source: DOT Office of Inspector General. Operational Errors (AV-2003-040) and

FAA Administrator’s Fact Book (November 2005).

The DOT Inspector General also highlighted potential problems in the use of

controllers-in-charge (CICs), a program using senior controllers rather than managers

to supervise facility operations, which was greatly expanded in recent years. Their

study found that while the use of CICs increased 13.6% between 2000 and 2001, the

number of operational errors while CICs were on duty increased by 45.7%. While

52

Department of Transportation, Office of Inspector General. Operational Errors and

Runway Incursions: Progress Made, but the Number of Incidents is Still High and Presents

Serious Safety Risks (AV-2003-040), April 3, 2003.

CRS-41

other factors may have contributed to this rise in error rates, this trend may be an

indicator that tighter controls and monitoring of the program may be needed.

Both the DOT Inspector General and the NTSB have criticized FAA policy and

agreements with controllers that limits the use of remedial training following

operational errors. FAA policy does not require the FAA to impose remedial training

following a low severity operational error and prohibits follow-on training if the

controller took corrective actions during the course of the event. Even for controllers

who have moderate or high severity operational errors, remedial training is not

required. Also, FAA policy prohibits supervisors from revoking or suspending

controller certificates and facility ratings on the basis of performance deficiencies.

In light of these findings, the DOT Inspector General concluded that FAA needs to

strengthen its actions to address controller performance deficiencies highlighted by

operational errors.

Even with improved oversight and safety regulation of air traffic facilities,

operational errors can still pose serious safety risks. In essence backup capabilities

are needed to assure aircraft separation by alerting controllers and pilots when a loss

of separation occurs and poses a threat of collision between two aircraft. These aids

include conflict alert (CA) algorithms to alert controllers to impending loss of

separation events, and TCAS to provide pilots with traffic awareness and conflict

resolutions for preventing midair collisions.

The August 31, 1986 collision of an Aeromexico D-9 and a small private plane

over Cerritos, California highlighted growing concerns over the risk of mid-air

collisions and prompted the FAA to promulgate regulations phasing in the use of

airborne traffic collision avoidance systems (TCAS) on airliners and commuter

aircraft.53 Currently, FAA regulations stipulate that passenger air carrier flights be

equipped with an operating TCAS system that provides visual and aural advisories

of traffic conflicts. Additionally, all aircraft operating near the nation’s busiest

airports are required to use altitude report equipment (Mode C or Mode S

transponders) that transmit aircraft position and altitude to TCAS devices.

Since these requirements have gone into effect, there has not been a mid-air

collision involving a TCAS-equipped aircraft in U.S. airspace. However, TCAS is

not required on all airplanes. Regulations stipulate that only passenger airliners and

jet and turboprop air taxi and commuter flights with seating for 10 or more

passengers must be equipped with TCA54S. Thus, most cargo aircraft, business jets,

and many charter aircraft are not required to install or use TCAS.

One option to increase safety as operations increase in congested airspace would

be to require the use of TCAS systems for other users of the aviation system. This

may be particularly important given the large anticipated increases in business jet and

53

National Transportation Safety Board. Collision of Aeronaves de Mexico, S.A. McDonnell

Douglass DC-9-32, XA-JED and Piper PA-28-181, N4891F, Cerritos, California, August

31, 1986. NTSB Report AAR-87-07.

54

Title 14, Code of Federal Regulations §121.356, §135.180.

CRS-42

cargo jet operations over the next 10 years. However, alternative technologies —

such as automated dependent surveillance-broadcast (ADS-B) with cockpit display

of traffic information (CDTI) or Traffic Information Systems (TIS) — have the

potential to offer TCAS-like capabilities at significantly lower cost, which may be

particularly attractive to general aviation users of business jets and mini-jets. Thus,

alternative technical standards for traffic awareness and alerting systems may be able

to adequately address safety concerns regarding traffic collision avoidance in the near

future. Congress may pursue the implementation of such systems through either

legislation or oversight of FAA regulatory activities.

Possible Strategies for Enhancing Capacity While

Maintaining Safety and Efficiency

There are numerous approaches to enhancing capacity of the national airspace

system under development and evaluation. The core policy issue is determining the

right mix for investing in airport infrastructure, technology, and modifications to

operational procedures in order to grow capacity at a rate commensurate with growth

in demand while at the same time maintaining the efficiency and safety that aviation

consumers expect. The aviation community has invested a great deal in future

concepts for air traffic management and control that are just beginning to mature and

take shape in the operational framework of the national airspace system.

Additionally, airports continue to expand and reconfigure to enhance their capacity

and improve operational efficiency. However, these measures may not be enough to

meet demand without eroding the efficiency and possibly the safety of air travel.

Consequently, policymakers are continuing to evaluate market-based strategies to

alter the demand characteristics for aviation operations so that operations can

continue at a level that is safe and meets consumer expectations of efficiency in a

resource constrained system.

The “Free-Flight” Concept

Over the next decade, the current model of the national airspace system is

expected to change dramatically. Virtually all airliners and business jets now have

onboard capabilities, such as area navigation equipment (RNAV), global positioning

system (GPS) receivers, and inertial guidance systems that provide precise aircraft

position data without sole reliance on ground-based VORs, thus allowing pilots to

fly directly from airport to airport. However, allowing aircraft to fly direct to their

destination presents significant challenges to air traffic managers and controllers that

are currently being worked out under a concept called free flight. Since free flight

is an evolving concept, the term is used both loosely to describe conceptual aspects

of future air traffic systems allowing aircraft to fly along direct routes and deviate as

needed to avoid weather and traffic, as well as more concretely to describe a suite of

air traffic management (ATM) and air traffic control (ATC) tools being developed

and tested by the FAA to allow greater flexibility in aircraft routing.

One step in the process toward implementing free flight is to redefine the

structure of high altitude airspace around point-to-point direct routes that

appropriately equipped aircraft can utilize. The FAA began doing this in July 2003,

defining and charting high altitude routes — designated by international convention

CRS-43

as “Q routes” in the U.S. and Canada — for use by aircraft with precision satellite

navigation capabilities.55

One major challenge in implementing the free flight concept is defining how

much autonomy each aircraft will have during the en route portion of flight.

Currently, aircraft in high altitude airspace can only fly along the specific course and

altitude profile that air traffic control has approved or cleared. Thus, in the present

system, ATC has direct control over every aircraft in high altitude airspace. Under

a free flight model it is likely that pilots would have some degree of autonomy

regarding their flight path. For example, in the current system if a pilot sees a

thunderstorm ahead, he or she must request a deviation around the storm from ATC.

Under the proposed free flight model, the pilot may be able to deviate around the

storm without formally receiving permission to do so by ATC. Similarly, pilots may

have some degree of autonomy regarding deviations for traffic, altitudes and

airspeeds deviations to avoid or mitigate turbulence and increase fuel economy, and

so on. This would shift the ATC role for high altitude airspace from direct control

to a supervisory control function, where ATC would monitor traffic in a given sector

of airspace and resolve conflicts as well as provide advisories and instructions to

maintain appropriate aircraft spacing and alleviate congestion at destination airports.

In the future, the en route controller is also likely to take on a more active role as an

interface between aircraft and air traffic management (ATM) functions within the

FAA that will apply more complex analyses of the overall traffic picture to more

efficiently control the flow of air traffic throughout the system.

A second major challenge in implementing a free flight model for the national

airspace system is handling the transitions from the busy terminal airspace around an

origin airport to the en route phase of flight along these routes and from the en route

segment to the approach phase of flight when aircraft enter busy terminal airspace

around a destination airport. The working concept to address this challenge is by

using what are referred to as pitch and catch points to define specific transition points

into and out from busy terminal airspace. Under this concept, aircraft would fly

predefined departure routes — much as they do today, except with the aid of

precision satellite navigation — to a pitch point where the would then proceed semiautonomously via a direct routing to a catch point where they would enter the

terminal airspace at the destination airport and follow predefined approach routes or

55

The FAA has defined advanced aircraft navigational performance capabilities broadly

under the umbrella of what they call Area Navigation or RNAV equipment. By establishing

performance standards in this manner, it does not limit operators to any specific technology

to meet the required navigational performance to perform certain operations. In this sense,

the FAA has moved away from technical standards and instead had adopted performance

standards for future navigation capabilities. At present, the aircraft technology needed to

meet these performance standards include Wide Area Augmentation System (WAAS)

enabled GPS receivers and inertial reference units (IRUs). The use of ground-based RNAV

systems developed in the 1970s that rely on VOR receivers and distance measuring

equipment (DME) to navigate using more direct routing is being evaluated under this

framework, but is not currently approved for high altitude airspace. In this report, the term

precision satellite navigation capabilities refers to the WAAS enabled GPS technology

which is one of two core enabling technologies of emerging free flight operational concepts

in the U.S.

CRS-44

ATC instructions to arrive at the destination airport. Thus, at least in the near term,

the free flight implementation that is most likely to emerge is one in which aircraft

will operate semi-autonomously in high altitude airspace between pitch and catch

points, and will operate under more direct control of ATC when transiting busy

terminal airspace during departure and before landing.

The core enabling technology needed to implement navigation under a free

flight system — precision satellite navigation — is already mature. The other

element needed to enable free flight — assuring safe separation between aircraft —

involves a more complex interplay between onboard technologies and air traffic

management and control tools. Onboard technologies for traffic awareness and

separation include TCAS systems which are already widely deployed. The other

onboard technology for traffic awareness and separation in aircraft is Automatic

Dependent Surveillance - Broadcast (ADS-B), a technology capable of broadcasting

aircraft position information to other aircraft and to air traffic control and displaying

traffic information in the cockpit. Unlike TCAS which uses onboard radar and radarbased air traffic control displays, ADS-B will rely predominantly on satellite-based

aircraft position data using GPS. The potential advantage of this technology is that

it can provide a common traffic picture, that is, the capability for pilots, and

controllers, and air traffic managers to have shared situation awareness regarding

nearby traffic and potential conflicts. Such a capability is seen as a step toward

providing pilots with more autonomy regarding navigation and separation. While

such technology has significant potential and has been implemented successfully in

various operational tests performed under the FAA’s Safe Flight 21 program, much

work is still needed to create a system-wide infrastructure to support this technology.

Much work is also still needed to develop decision support tools and automation that

can assist air traffic managers, controllers, and pilots to handle traffic and weather

conflicts. Finally, much work still needs to be done on the human factors and system

design of a free flight system to more clearly define the roles and protocols for air

traffic managers, controllers, and pilots.

The FAA is in the process of defining the regulatory structure to permit limited

operations exploiting this technology. However, significant work is still needed to

create a seamless, integrated free flight system throughout the domestic U.S. airspace.

As shown in Table 2, there is still considerable risk associated with integrating and

implementing free flight concepts in the national airspace system. At this point, this

risk exists although the core enabling technologies are relatively mature, because

extensive systems integration is still needed in order to utilize these technologies to

provide seamless navigation, communications, surveillance, and air traffic

management capabilities throughout the most complex airspace system in the world.

Despite ongoing reform with the creation of the ATO and the JPDO, the FAA’s

capability to implement free flight also introduces an element of risk because of the

FAA’s history of cost overruns, schedule delays, and failures to meet performance

objectives in managing large scale programs. Given the relatively high level of risk

associated with implementing free flight concepts, this could be an area of continued

congressional oversight over the next several years.

CRS-45

Table 2. Risk Elements and Considerations for Implementing

Free Flight Concepts

Element

Risk Considerations

Technology

Core technologies (e.g., GPS, ADS-B) are mature;

but

Extensive systems integration, both hardware and software, is

needed

Application

Domain

Highly complex airspace system;

Highly complex interactions between human operators (i.e., air

traffic managers, controllers, and pilots);

Extensive requirements for collaboration/information sharing; and

Highly dynamic scenarios (e.g., weather and traffic flow variations)

Program

Management

Historically, FAA programs have been plagued by cost overruns,

schedule delays, and failures to meet performance objectives;

Historically, FAA has “stovepiped” or compartmentalized projects

with inadequate integration and inter-project collaboration;

Historically, FAA has had inadequate and incomplete blueprints for

system integration and technology investment strategies;

ATO and JPDO were established to correct management deficiencies

at FAA but are too new to assess their effectiveness;

FAA is implementing incremental, spiral development processes and

other acquisition reforms to address concerns

Reducing Separation Standards

In parallel with the FAA’s efforts to introduce free flight concepts in the

national airspace system, the FAA is implementing initiatives to reduce the

separation between aircraft both in high altitude airspace and in the terminal

environment, near airports. Reducing separation is seen as an important strategy for

increasing capacity in congested airspace.

For example, reducing vertical separation from 2,000 feet to 1,000 feet in high

altitude airspace56 in essence doubles en route capacity, although actual capacity

enhancement through RVSM is likely to be constrained to some degree by factors

such as airspace configuration and air traffic controller workload that may limit the

number of aircraft that can be handled within an air traffic control sector. Only with

the advent of more autonomous means of navigation and surveillance of air traffic,

using free-flight direct navigation concepts and pilot/controller decision aids for

56

High altitude airspace, as used in this report, refers to airspace between 18,000 feet and

60,000 feet (Flight Level (FL) 180 to FL600, which is classified as Class A airspace.

CRS-46

example, will technology and operational procedures allow for this increase in

capacity to be fully exploited. Nonetheless, in the near term, RVSM is expected to

have numerous benefits including:

!

!

!

!

!

!

Reduced fuel burn from improved routing, altitude selection, and

delay reduction;

Increased air traffic sector capacity, throughput, and efficiency;

Increased controller flexibility for resolving weather and traffic

conflicts;

Decreased controller workload by providing controllers with more

options;

A reduction in conflict points in high density traffic areas; and

Enhanced predictability by allowing aircraft to use requested

altitudes.

In high altitude airspace, efforts are underway to reduce the vertical separation

between aircraft from 2,000 feet to 1,000 feet. RVSM requirements are now in effect

for many oceanic and international flights operated between 29,000 feet (FL290) and

41,000 feet (FL410). Domestic RVSM requirements covering the lower 48 states

and Alaska will be required by January, 2005

The Domestic RVSM implementation will make six additional flight levels

available for operations between FL 290-410. According to the FAA, RVSM has

been shown to enhance aircraft operating efficiency by making more fuel/time

efficient flight levels available and enhance air traffic control flexibility in addition

to providing the potential for enhanced en route airspace capacity.

While RVSM is designed to target capacity expansion in high altitude airspace,

reducing separation standards near airports is seen as an important strategy to

improving capacity and efficiency of arrivals and departures. One major hurdle to

overcome in implementing this strategy is that many airports have been built with

runways that are too close together to support simultaneous arrivals using current

separation requirements. Therefore, the FAA is working on technology and

procedures to reduce the separation between aircraft operating to closely spaced

parallel runways by providing pilots and controllers with precision aircraft and traffic

position information that will allow operations to continue under visual separation

rules during periods of marginal in-flight visibility. In the future, aircraft meeting

specific levels of navigational accuracy — called required navigation performance,

or RNP57 in aviation parlance — may be able to use cockpit traffic displays in lieu

57

Required navigational performance (RNP) is a performance standard that defines

the required position accuracy needed to keep the aircraft within a specified

containment area, or bubble, 99.9% of the time. The required navigational

performance is not tied to any specific technology, but sets a technical standard that

can be met using various FAA-approved equipment. While precision satellite-based

navigation is currently the principal technology for meeting RNP standards, these

standards allow for the use of other technologies — including yet to be developed

technologies — to meet navigational performance standards.

CRS-47

of out-the-window visual confirmation of traffic position to see and avoid nearby

traffic approaching parallel runways in virtually all weather conditions.

Like free flight, reduced separation standards in the terminal environment near

airports are likely to rely heavily on precision satellite navigation capabilities

provided by the global positioning system (GPS) augmented by ground-based

stations that provide increased precision in the GPS signal. The FAA has two

systems for precision satellite navigation - the recently commissioned Wide Area

Augmentation System (WAAS) that provides systemwide coverage and the higher

resolution Local Area Augmentation System (LAAS) which may provide more

precise navigation capability for precision landings during low visibility operations

at selected airports. While WAAS is operationally available, LAAS is still in early

testing phases of operational testing and there are some that still question whether the

improvement in navigational accuracy of current LAAS systems over WAAS is

enough to justify their cost.58

The FAA turned on the WAAS network on July 10, 2003 and is now phasing-in

landing procedures that can exploit the precision vertical and lateral navigation

capabilities of GPS/WAAS. WAAS is a milestone achievement because it offers the

potential for precision vertical and lateral navigational guidance to practically any

runway in the United States in addition to providing improved accuracy of aircraft

position data needed to reduce aircraft separation standards.59

In terms of capacity enhancement, WAAS provides two key benefits. First,

WAAS can be used as a means to allow more precise spacing of aircraft on approach

to an airport. This can permit runway utilization to better approach optimal levels.

In the future, the precision of WAAS enabled GPS position data may allow for the

reduced separation of aircraft on approach and may also reduce the separation of

aircraft arriving on closely spaced parallel runways. The second way WAAS can

enhance capacity is by providing precision landing capabilities to many general

aviation reliever airports. In poor weather, the only available landing sites with

precision landing capabilities offered by current airport-based instrument landing

systems (ILS) are often commercial airports and large general aviation reliever

airports. Consequently, commercial airports often see increased general aviation

activity during poor weather because general aviation aircraft are forced to use these

landing facilities. With new instrument approach procedures exploiting WAASenabled GPS navigation, numerous other airports can potentially relieve commercial

airports of general aviation traffic during reduced visibility conditions. Thus, the

potential benefit of precision satellite navigation extends beyond providing the

capability to reduce separation standards.

58

59

John Croft. “More WAAS, less LAAS.” Professional Pilot, April 2003, pp. 60-64.

While WAAS provides the capability for precision vertical guidance to virtually all

runways, terrain, obstacles, noise abatement and other factors may limit its implementation

at some airports.

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Automation and Decision Aiding for Air Traffic Management

The future national airspace system is likely to make extensive use of

automation and decision aiding tools to more efficiently manage traffic flow in a free

flight environment with reduced aircraft separation. Many experts see automation

and decision aiding tools as a core element of the next generation airspace system

that will allow users to more fully exploit the capabilities of precision satellite

navigation and enhanced communications and surveillance capabilities. According

to the JPDO director, Charles Keegan, a central concept of the NGATS is to rely

extensively on the automation of core air traffic management functions such as flow

control and the metering or spacing of aircraft.60

The FAA and NASA are actively engaged in the research and development of

several tools that may someday provide essential automation and decision aiding

capabilities to air traffic managers, controllers, and pilots in the future national

airspace system. One precursor to future decision aiding capabilities to enable users

to exploit en route free flight concepts is the user request evaluation tool (URET)

currently being deployed at en route air traffic facilities. URET predicts and notifies

controllers of potential conflicts between aircraft or special activity airspace and

provides conflict assessments of proposed flight path changes. Presently, URET has

been deployed at six Air Route Traffic Control Centers (ARTCCs) as part of the first

phase of FAA’s free flight implementation and installation at the remaining 14

ARTCCs is underway as part of the second phase of free flight implementation.

Another component of high altitude free flight enabling technology is the Traffic

Management Advisor (TMA), a strategic planning tool for high altitude controllers

and traffic management specialists. The TMA is used for arrival schedule planning

to implement time based metering or sequencing of aircraft for the handoff between

en route phases of flight and approach to airports in congested airspace. A related

tool designed to also improve flow control is the passive final approach spacing tool

or pFAST. As the name suggests, pFAST has been designed to serve as a decision

aid for controllers to better optimize traffic flow during the final approach to a

runway. While these tools are currently making their way into air traffic control

centers and approach control facilities, they may not offer complete solutions to air

traffic management. Extensive work is still likely to be needed to integrate these

various tools and concepts on a system-wide level in order to enable more optimal

utilization of airspace and more efficient flow of air traffic.

In the future, integrated air traffic management concepts and collaborative

decision making are likely to increase in importance and allow the FAA to develop

strategies and tactics for handling system-wide traffic flow. The FAA may

increasingly rely on traffic management tools to aid strategic and tactical decisionmaking. The national playbook is one example of a traffic management tool

currently implemented to give the FAA the ability to deploy specific situation-based

tactics for handling capacity constraining conditions such as adverse weather. The

national playbook provides the air traffic control system command center

(ATCSCC), the nerve-center for FAA’s air traffic management operations, other

FAA facilities, and system users a common set of strategies for various scenarios.

60

David Hughes. “The ‘Silent’ Crisis”.

CRS-49

The purpose of the national playbook is to aid the FAA and system users in

expediting route coordination during the most common scenarios that occur during

severe weather. The selected routes in the national playbook include textual and

graphical depictions of specific routing tactics that have been vetted by air traffic

control representatives from affected facilities involved in a given scenario.

Another operational tool that the FAA recently began implementing is the use

of “express lanes” to temporarily increase the flow out of airports experiencing

departure delays. The concept is that specific levels of delay will trigger the tactical

implementation of these “express lanes.” When this happens, air traffic controllers

will hold up traffic to and from nearby satellite and reliever airports to allow

departures from the major airport to flow more quickly through these “express lanes”

in the sky that open up as a result. In the future, air traffic managers may rely more

extensively on these strategies and tactics and rely more heavily on the use of

automation and decision aiding tools to optimize airspace utilization and traffic flow

management.

However, despite the FAA’s focus on air traffic management technologies and

methods to improve future airspace utilization and increase the efficiency of traffic

flow, these efforts are not believed to be capable of fully addressing capacity needs

by themselves. As discussed previously, one of the main challenges for meeting

aviation capacity needs appears to be linked to the future capability to expand airport

infrastructure, such as new runways and new airports, in major metropolitan areas

where demand for air travel is expected to grow significantly over the next 25 years.

While increased automation and decision aiding to support air traffic managers,

controllers, and airspace users will help to optimize the utilization of underlying

infrastructure, experts generally agree that expansion and reconfiguration of airport

infrastructure is likely to provide the most substantial gains in available capacity of

the national airspace system.

Airport Expansion and Reconfiguration

As the FAA notes, there are two main strategies for alleviating peak demand at

airports: building new runways; and maximizing the use of existing runways.61 As

indicated from models in the FAA’s capacity benchmark studies, new runways can

significantly increase an airports capacity. Of the twelve OEP-35 airports building

or planning new runways, those new runways are expected to net an average capacity

improvement of 31% across all weather conditions.62 By comparison, technology

improvements at airports are expected to net more modest capacity increases in the

3 to 8 percent range.63 Thus, any systemwide strategy to enhance capacity is likely

to focus heavily on building new runways. Technology enhancements to improve the

usage of existing infrastructure, while important, do not appear to be capable of

keeping pace with near-term growth in airport operations.

61

Federal Aviation Administration. Operational Evolution Plan (Version 6.0).

62

Based on FAA Airport Capacity Benchmark Report 2004 data.

63

Federal Aviation Administration. Airport Capacity Benchmark Report 2001.

CRS-50

Expanding capacity at airport level, either by adding new runways or by building

new airports in metropolitan areas, requires extensive cooperation between the

federal government, local and state entities, airport authorities, and industry and

community stakeholders. For this reason, airport expansion plans are often

contentious, time consuming, and challenging. The growing need for expanded

airport infrastructure throughout the aviation system is pressuring the FAA and

airport operators to seek more streamlined methods for planning and addressing

regulatory compliance issues, such as environmental considerations, in the planning

process. Partnerships and close cooperation between the FAA, airport operators,

state and local governments and stakeholders, such as airlines and impacted

communities, are likely to become more critical in determining the best course of

action to expand regional capacity for aviation operations while minimizing

environmental impacts and integrating proposed solutions with other regional

transportation objectives. As a step toward addressing these challenges, Vison 100

(P.L. 108-176) included provisions to streamline the environmental review process

for airport capacity enhancement projects by designating the DOT as the lead agency

in these assessments and directing the Secretary of Transportation to develop a

coordinated review process including simultaneous review by all involved

government agencies. The objective of these provisions is to reduce the amount of

time and number of reviews required for airport expansion projects.

One major hurdle for many airports in congested areas is available land. Many

airports in major metropolitan areas lack the available land to build on. Moreover,

the acquisition of surrounding land to accommodate new runways is often not a

viable option, and even when it is, doing so is a time consuming and resource

intensive process that often takes several years. Some experts believe that one

alternative solution is to construct closely spaced parallel runways in hopes that

technology will be able to provide the capability to operate these runways at high

capacity levels under most, if not all, flyable weather conditions.64 There are several

challenges to doing this. Probably the most significant challenge is designing

runways and taxiways for safe and efficient surface movement between multiple

closely spaced parallel runways. There are complex operational challenges for

handling arrivals that need to taxi across active runways, and safety concerns about

runway incursions make the use of multiple, closely spaced parallel runways a

particular challenge.

Another significant challenge is the separation requirements imposed to prevent

wake turbulence encounters which currently limits the capacity of closely spaced

runways significantly. Wing-tip vortices produced by heavy jets pose a danger to

trailing aircraft that presently are dealt with by spacing aircraft several miles apart.

Reducing this separation is an important element of optimizing the usage of closely

spaced runways. Many experts see great promise in ongoing wake vortex research

and development at NASA’s Langley Research Center that may someday lead to the

operational deployment of a wake turbulence prediction tool for airports.65 However,

reducing aircraft separation based on the use of such a tool in an airport environment

64

David Hughes. “2025 squeeze play.” Aviation Week & Space Technology, November 15,

2004, p. 44-45.

65

Ibid.

CRS-51

is still likely to be several years away. In addition to these challenges, significant

human factors challenges related to controller workload and traffic situation

awareness likely will need to be addressed before a viable means for reducing

separation and conducting simultaneous operations on closely spaced runways can

be implemented without compromising safety.

Market-Based Options

Data indicate that, at best, through airport expansion and improvements, and

through implementation of technology solutions to enhance the capacity of the

national airspace system, the FAA will struggle to keep pace with the growth in

demand for air travel. Thus, there may be a growing need to examine alternative

means to alleviate congestion and delay in the aviation system. One particular

strategy that may be examined is the use of market-based approaches that, in essence,

alter the demand characteristics of aviation operators in ways designed to make

demand for aviation services more commensurate with available capacity in order to

maintain efficiency and safety of operations.

These market-based options vary along a continuum of government involvement

(see Figure 12). On one end of the continuum, airlines and other operators could be

left to work it out amongst themselves to define market approaches and schedules

that will cause minimal delay. In some cases, there could be limited government

involvement in these activities, such as having the FAA or DOT serve as a mediator

during discussions of scheduling or as an observer to ensure that there is no collusion

or other violation of antitrust statutes and regulations and that no specific user groups

are unfairly disadvantaged in establishing schedules and access to airports. The

government may take a somewhat more active role in such activities by discussing

air traffic concerns over proposed schedule options, or even, suggesting scheduling

options based on air traffic management considerations and models of traffic flow.

Figure 12. Continuum of Government Involvement in Market-Based

Strategies to Alleviate Aviation Congestion

Options

Industry

Collaboration

On Scheduling

Government Mediation

In Scheduling Practices

Active Participation with Industry

On Scheduling

Government Offered or

Recommended Scheduling Solutions

Quota and Slot Systems

Low

Moderate

Level of Government Involvement

High

CRS-52

Another way in which government could exert limited control over scheduling

practices is to implement incentives for off-peak

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