Review of the FAA 1982 National Airspace

System Plan

August 1982

NTIS order #PB83-102772
Library of Congress Catalog Card Number 82-600595

For sale by the Superintendent of Documents,

U.S. Government Printing Office, Washington, D.C. 20402
Foreword

In January 1982, shortly after OTA had concluded an assessment of the airport

and air traffic control system, the Federal Aviation Administration released the 1982

National Airspace System (NAS) Plan. The Transportation Subcommittee of the House

Committee on Appropriations asked that OTA undertake a review of the NAS Plan,

building on the results of the assessment that had been carried out at their request.

OTA’S approach to conducting this review was to examine the NAS Plan at two

levels—the adequacy of the plan as a whole and the appropriateness of the specific technologies selected by FAA for implementation. Our aim was to make a balanced assessment—pointing out those parts that are commendable and supported by the aviation

community while also identifying alternatives that merit consideration and indicating

aspects of the plan that could be improved. In so doing, it was our intent to assist the

congressional review process and to make a constructive contribution to the generally

shared goal of modernizing and improving the air traffic control system in the years

to come.

In conducting this review, OTA held extensive consultation with representatives

of the aviation community and with technical experts in the fields of computer and communication technology. Workshops on aviation growth forecasts and air traffic control

technology were held, and a z-day conference of aviation experts was convened to evaluate FAA’s planned modernization of the National Airspace System. The results of this

consultative effort combined with analysis performed by OTA staff and the work carried out in the previous assessment form the basis for this OTA report.

In all, some 60 persons from outside OTA took part in the review of the NAS Plan.

Their contributions were remarkable both for their depth and richness of insight and

for the diversity of opinion on the strengths and weaknesses of the plan. We accept

full responsibility for the analysis presented here, but acknowledge our debt to those

who contributed so freely of their time and effort on our behalf. We are particularly

grateful to the Congressional Budget Office for their assistance in analyzing traffic

forecasts and funding issues.

Director

. Ill
Review of FAA’s 1982 National Airspace

System Plan Project Staff

John Andelin, Assistant Director, OTA

Science, Information, and Natural Resources Division

William Mills, Program Manager

Space, Transportation, and Innovation Program

Larry L. Jenney Paul B. Phelps Zalman Shaven

M. Karen Gamble Marsha Fenn R. Bryan Harrison*

OTA Publishing Staff

John C. Holmes, Publishing Officer

John Bergling Kathie S. Boss Debra M. Datcher Joe Henson

“Contractor.
Working Group #1—ATC Growth

Robert W. Simpson, Chairman

Professor, Flight Transportation Laboratory

Massachusetts Institute of Technology

Samuel C. Colwell

Director, Market Planning

Fairchild Industries, Inc.

Herman Gilster

Manager, Traffic and Economic Forecasting

Boeing Commercial Airplane Co.

David Lewis

Principal Analyst, Natural Resources and

Commerce Division

Congressional Budget Office

David J. McGowan

Manager, Systems Operations

General Aviation Manufacturers Association

Robert E. Monroe

Vice President, Data Research

Aircraft Owners & Pilots Association

Barney Parrella

Manager, Airport Planning and Development

Air Transport Association

Gilbert F. Quinby

Consultant

John Slowik

Vice President

Airline and Aerospace Department

Citibank N.A.

Working Group #2—Computer and Communication Technologies

H. Clark Stroupe, Chairman

Vice President

Booz-Allen & Hamilton, Inc.

Michael J. Ball

U.S. Air Force

Paul Baran

President

Cable Data Associates

W. W. Buchanan

Senior Associate

SES

James Burrows

Director

Institute for Computer Science and Technology

Anthony Csicseri

U.S. General Accounting Office

George Litchford

President

Litchford Electronics

Gilbert Quinby

Consultant

Harrison Rowe

Bell Laboratories

Crawford Hill Laboratory

Willis Ware

The Rand Corp.

vi
OTA Conference on the National Airspace System Plan Attendees

John L. McLucas, Chairman

President

Comsat World Systems

Ward Baker

Airline Pilots Association

Frederick Bradley, Jr.

Vice President

Citibank, N.A.

Samuel C. Colwell

Director, Market Planning

Fairchild Industries, Inc.

Barbara Corn

BD Systems, Inc.

Anthony Csicseri

U.S. General Accounting Office

Elwood T. Driver

Former Vice Chairman

National Transportation Safety Board

Thomas S. Falatko

Deputy for Transportation and Civil Aviation

U.S. Air Force

Matthew Finucane

Director

Aviation Consumer Action Project

Rod Gilstrap

Director

Flight Safety and Operations

United Air Lines

William T. Hardaker

Assistant Vice President

Air Transport Association

William Horn, Jr.

National Business Aircraft Association

Victor J. Kayne

Senior Vice President

Technical Policy and Plans

Aircraft Owners & Pilots Association

David Lewis

Congressional Budget Office

John Leyden

Executive Director

Public Employees Department

AFL-CIO

Kingsley G. Morse

Chairman

Regional Airlines Association

Gilbert F. Quinby

Consultant

J. Donald Reilly

Executive Vice President

Airport Operators Council International

Harrison Rowe

Bell Laboratories

Crawford Hill Laboratory

Robert C. Seamans, Jr.

Professor of Environment and Public Policy

Massachusetts Institute of Technology

Robert Simpson

Flight Transportation Laboratory

Massachusetts Institute of Technology

H. Clark Stroupe

Vice President

Booz-Allen & Hamilton, Inc.

Richard W. Taylor

Vice President

Boeing Commercial Airplane Co.

David Thomas

Consultant

General Aircraft Manufacturers Association

Vincent Volpicelli

Supervising Engineer

Port Authority of New York and New Jersey

vii
Contents

PART l–REVIEW

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Airport and ATC System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Basic Findings on the Airport and ATC System . . . . . . . . . . . . . . . . . . . . . . . . . .

The 1982 National Airspace System Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General Comments . . . . . .

Addressing Future Requirements

Priorities . . . . . . . . . . . . . . . . . . . . 

Schedule . . . . . . . . . . . . . . . . . . . . .

FAA Aviation Forecasts . . . . . . . . . .

Accuracy of Past Forecasts . . . . .

Forecast Methodology . . . . . . . . .

Growth Assumptions in the 1982 NAS Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Constraints on Future Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specific Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

System Design and Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

En Route Computer Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Automation and Human Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Communication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Collision Avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Satellite Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Impacts on Airspace Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General Aviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Department of Defense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cost and Funding Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

User Fees. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cost Allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Alternative Methods of Taxation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Other Funding Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

3

7

7

7

9

9

9

10

10

13

13

16

17

17

21

21

22

24

26

26

27

29

29

30

33

33

34

36

37

PART 2 – APPENDIXES

Appendix A—Growth Scenarios in FAA’s National Airspace System Plan..... 41

Attachment A-l: CBO Analysis of FAA Forecast Accuracy and Model . . . . . 48

Attachment A-2: Comparison of FAA Forecasts With Industry Forecasts. . . . 50

Appendix B—Computer and Communication Technologies in FAA’s

National Airspace System Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Attachment B-1: Excerpt From “Scenarios for Evolution of

Air Traffic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

ix
Appendix C—OTA Conference on the National Airspace System Plan . . . . . . . 62

Attachment C-l: Agenda and List of Participants . . . . . . . . . . . . . . . . . . . . . . . . 62

Attachment C-2: Summary of Questionnaire Responses . . . . . . . . . . . . . . . . . . . 64

Attachment C-3: Summary of the Conferees’ Views 68

TABLES

Table No. Page

l. FAA Forecasts Compared With Actual Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2. Comparison of Rehosting and Upgrading 9020As to 9020Ds . . . . . . . . . . . . . 23

3. FAA Budget Estimates, Fiscal Years 1983-87 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

4. Past and Future FAA Expenditures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5. FAA Budget and Cost Recovery, Fiscal Years 1983-87 . . . . . . . . . . . . . . . . . . . . 34

6. Cost Recovery Under the Administration’s Proposed User Fees . . . . . . . . . . . . 35

A-1-l .Five-Year Aviation Activity Forecasts Compared With Outturn . . . . . . . . 48

A-1-2 .Summary of Forecast Periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

A-1-3. FAA Forecasting Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

FIGURES

Figure No. Page

l. FAA Tower Workload, Actual and Forecast, 1960-2000 . . . . . . . . . . . . . . . . . . 14

2. FAA En Route Workload, Actual and Forecast, 1960-2000 . . . . . . . . . . . . . . . . 15

3. FAA Flight Service Workload, Actual and Forecast, 1960-2000 . . . . . . . . . . . . 15

A-2-l. Forecasts of 1980 Domestic Air Traffic, 1966-79 . . . . . . . . . . . . . . . . . . . . . 50

A-2-2. Forecasts of 1985 Domestic Air Traffic, 1966-82 . . . . . . . . . . . . . . . . . . . . . 50

A-2-3. Comparison of Industry Forecasts of Domestic Air Traffic

in 1985 and 1990.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

A-2-4. Market Forecast for U.S. Commercial Jet Passenger FleeL 1980-2000 . . . 51
PART 1

The Review
EXECUTIVE SUMMARY

The National Airspace System Plan (NAS Plan)

released by the Federal Aviation Administration

(FAA) in January 1982 outlines the agency’s most

recent proposals for modernizing the facilities and

equipment that make up the air traffic control

(ATC) system. The plan attempts to integrate the

various improvements into a single long-range

program that addresses major shortcomings and

reduces costs of the current system. Viewed on

this high level—as a statement of policies, goals,

and directions—the NAS Plan is to be commended as a significant and even bold step compared with past FAA efforts to chart the future

evolution of the system.

The national airspace system is a “three-legged

stool” made up of airports, the ATC system, and

procedures for using the airspace. While all three

need to be improved in an integrated fashion, the

NAS Plan deals with only one leg—the ATC system. OTA’S assessment of the airport and ATC

system found that lack of airport capacity—not

ATC technology—will be the principal limit on

the growth of aviation. The NAS Plan acknowledges that “capacity limitations at busy airports

will be the constraining element” in the system,

but it concentrates on ATC technology, and most

of the proposed improvements are directed at

modernization of the en route, not the terminal

area, portion of the system.

FAA does intend to address the problems of airports and airspace procedures. A revised plan for

airport development is to be issued later this year.

FAA has also just begun a National Airspace Review (NAR), a 42-month effort that will reexamine the rules and procedures governing the use of

the airspace. Still, by issuing first a plan for modernizing ATC technology, without waiting until

the other efforts have more thoroughly defined

needs in the area of airports and airspace procedures, FAA may be placing too much emphasis

on technological solutions. This perception is reinforced by the NAS Plan itself, which gives first

priority to improved technology for the en route

system by the late 1980’s. There is little apparent

advantage in seeking to move en route traffic

more expeditiously only to have it encounter delays in terminal areas, where capacity improvements are not scheduled to be made until the early

1990’s.

With these reservations, the FAA plan for ATC

system improvements is comprehensive. The proposed changes are technologically feasible, and

they are consistent with the goals of increasing

safety and productivity and accommodating future growth. Providing capacity to accommodate

anticipated growth was a principal factor in developing the NAS Plan, although other factors were

also involved—increased reliability, safety, productivity, and fuel savings. Still, the technological

strategy and implementation schedule appear to

have been driven by forecasts of aviation growth

and near-term capacity problems at en route centers. FAA traffic and workload forecasts have

tended to be too high in the past, however, and

in some cases technological alternatives that might

be equally effective or less costly than those selected by FAA appear to have been rejected because of the anticipated rate of growth in demand

for ATC services. OTA’S review of the NAS Plan

suggests that FAA forecasts may not be a useful

guide to long-term planning and investment, and

that some of these technological options may

therefore warrant reexamination.

In the area of en route computer replacement,

for example, some believe it would be prudent to

adopt a strategy for interim steps to be taken in

the 1980’s that imposes no constraints on the design of the new system that will serve for the

1990’s and beyond. FAA’s proposed approach is

to “rehost” the existing software on new computers, and then to develop new software to run on

the host computers for use with the advanced sector suites to be installed by 1990. Several experts

have told OTA that this approach might limit the

options available in designing the new system. In

their view, any interim host would have to be

replaced when the new system comes on line. FAA

admits this possibility, but maintains that the intent is for the host computer to serve as the basic

processor for the ATC system until well into the

1990’s. An alternative short-term approach would

be to make selective enhancements to the present

technology —i.e., upgrade the current computers

in the centers where capacity problems are

3
4 ● Rwiew Of the FAA 1982 National Airspace System Plan

expected—in combination with economic or regulatory approaches to demand management, while

proceeding without delay on a parallel effort to

develop by 1990a totally new ATC system design

that makes best use of technologies then available

and that will serve until beyond the turn of the

century.

As a blueprint for the modernization of the

ATC system, the 1982 NAS Plan does not provide a clear sense of the priorities or dependencies

among its various program elements. Nor does

the plan deal explicitly with contingencies or

delays caused by engineering problems or by the

possible deletion of some elements due to budgetary constraints. Given the complexity and magnitude of this undertaking, FAA may have set itself

an overly ambitious schedule for implementing

the proposed improvements.

OTA’S review of the 1982 NAS Plan has also

identified the following specific findings and

issues:

●

●

Growth. —FAA’s traffic forecasts have been

too high in the past and there are questions

about the methodologies and assumptions

underlying the projections on which the NAS

Plan is based. Overestimation may have led

FAA to foreclose technological options and

accelerate the implementation schedule unnecessarily. It may also have led FAA to

overestimate the user-fee revenues that will

be available to pay for the proposed improvements.

En Route Computer Replacement. —FAA’s

option analysis issued in January 1982 supports upgrading the 10 en route computers

that face capacity problems. ’ The NAS Plan,

released at about the same time, calls instead

for replacing the computer hardware (called

rehosting the software) in all 20 centers as

a part of a long-term plan to increase productivity and reliability as well as capacity. OTA

does not find persuasive the reasons advanced by FAA for rejecting the previously

preferred option of upgrading only selected

I Federal Aviation Administration, “Response to Congressional

Recommendations Regarding the FM’s En Route Air Traffic Control Computer System, ” report to the Senate and House Appropriations Committees pursuant to Senate report 96-932, DOT/FAA/

AAP-82-3, January 1982.

●

●

●

en route centers. In addition, the choice of

a host computer now may limit the options

available to the contractor for the sector suite

and software. OTA conferees were sharply

divided in their views on this question. Some

felt that the choice of a host computer now

might limit future ability to benefit from a

distributed computer architecture, local area

networking, and new techniques in software

development. Others believed that, if the

host is chosen judiciously, the transition to

a new system embodying these advanced and

desirable features could be made without difficulty.

Automation. —While the NAS Plan envisions

substantial cost savings due to extensive automation, supporting analysis is not provided

in the plan. This analysis is probably still in

progress and may take some time to complete, but it would be useful for the interim

results to be made available to assist in congressional review of the automation portions

of the overall plan. In addition, there is concern on the part of some experts about the

ability of human operators to participate effectively in such a highly automated system

and to intervene in the event of system error or failure.

Satellites. —Satellite technology has significant potential applications for communication, and eventually for surveillance and navigation. FAA does not see a role for satellites

in the period covered by the NAS Plan.

FAA’s decision against satellites appears to

have been driven by timing and present cost

effectiveness, rather than technology readiness or long-term system advantages.

User Effects. —A great many of the proposed

ATC system improvements are directed to

the needs of traffic operating under the instrument flight rules (IFR), particularly while

en route at cruise altitude. These improvements will benefit FAA itself by automating

functions and reducing labor costs. The principal beneficiaries among users will be air carriers and larger business aircraft. Personal

general aviation (GA) users could receive improved weather information, an important

benefit; but in order to obtain this benefit and

other operational advantages of the new sys-
Executive Summary ● 5

●

tern, more avionics will be required, and

there would be restrictions on access to airspace by aircraft not so equipped. The Department of Defense (DOD) too, is concerned

about the cost of new ATC avionics and feels

that the new plan must be carefully coordinated with the military services to ensure

that their mission needs and responsibilities

for administration of the airspace are integrated with those of FAA.

Cost and Funding. —Implementing the improvements proposed in the 1982 NAS Plan

would more than double FAA’s facilities and

equipment budget through 1987, compared

to the last 10 years. FAA has not yet released

cost estimates for completing the proposed

programs, but it seems likely that expenditures of like magnitude will be needed in the

years beyond 1987. FAA proposes to recover

85 percent of its total budget through user

fee revenues and a drawdown of the uncommitted Trust Fund balance. The user fee

schedule would perpetuate the existing crosssubsidy from airline passengers and shippers

of air cargo to GA. Business aviation would

benefit particularly because of the extensive

use these aircraft make of the IFR system. In

addition, higher user fees may dampen the

growth of aviation, thereby reducing the revenues expected to pay for the proposed improvements.
THE AIRPORT AND ATC SYSTEM

BACKGROUND

In December 1981, OTA completed an assessment of the airport and ATC system, with emphasis on the problem of congestion at major hubs

and the feasibility, cost, and impacts of prospective improvements in ATC technology. This assessment drew on information published by FAA

through 1981 and focused on three central topics:

●

●

●

scenarios of future aviation growth;

alternatives for increasing airport and terminal area capacity; and

ATC system modifications proposed by

FAA.

In January 1982, FAA issued a new NAS Plan

for the modernization of the ATC system through

the year 2000. The House Committee on Appropriations, Subcommittee on Transportation,

which had requested the original OTA assessment, asked OTA to undertake a 3-month followon study to review the 1982 NAS Plan and to provide the subcommittee with the following support:

● a critique of the NAS Plan, with emphasis

on changes from previous proposals;

● a delineation of technological options and alternative implementation strategies within

the general framework of the Plan; and

● an analysis of issues raised by the Plan, such

as benefits and costs to airspace users and the

Government, and identification of questions

needing further study or clarification.

The NAS Plan proposes many improvements to

the ATC system—including replacement of computers, increased automation, modernization of

the communication network, consolidation of

ATC facilities, and upgrading navigational aids,

OTA’S review focuses on the computer replacement, communications, and automation issues

that are the heart of the Plan.

OTA’S response to the subcommittee’s request

draws on the findings of the recently completed

assessment, which are outlined below, supplemented by a series of meetings with representatives of the aviation community and experts in

the fields of computer and communications technology. Working Group No. 1 met on February

25, 1982, to discuss aviation growth scenarios and

to examine the specific methodology and economic assumptions underlying the aviation forecasts

on which FAA based the 1982 NAS Plan. Working Group No. 2 met on March 9, 1982, to discuss

the specific computer and communications technologies proposed by FAA, alternative technologies that are not included in the NAS Plan, and

the technical and scheduling risks involved in

FAA’s proposed implementation strategy. OTA

also held a general conference of aviation and

ATC technology experts on April 1 and 2, 1982,

to discuss four major issues arising from the NAS

Plan: aviation growth, proposed changes in ATC

technology, effects on airspace users, and strategies for funding system improvements.

BASIC FINDINGS ON THE AIRPORT AND ATC SYSTEM

OTA’S assessment of the airport and ATC system arrived at several major findings, which have

been generally confirmed by the subsequent review of the 1982 NAS Plan. Findings related to

technological options are discussed later in the section entitled “Specific Technologies. ” OTA findings in other areas are summarized below.

● Congestion and delay in the system result primarily from the concentration of air traffic at

a few major hub airports. —There are over

6,000 public-use airports in the United States,

of which 435 have FAA control towers. However, the 10 busiest airports handle 33 percent

of all commercial operations and 47 percent of

all passenger enplanements. The Nation’s 60

major metropolitan areas account for 90 percent of all enplanements, 75 percent of all commercial operations, and 40 percent of all itinerant aircraft operations, including GA.

7
8 . Review of the FAA 1982 National Airspace System Plan

●

●

●

There will be continued growth in the demand

for ATC services through 2000, but the rate of

traffic growth will be lower than in the last 20

years and probably lower than projected in

FAA aviation forecasts. —FAA forecasts have

consistently overestimated traffic growth in the

past, and the latest forecasts still seem too high.

A number of factors suggest that the air carrier industry is already approaching its mature

size and will grow slowly over the next two decades. FAA workloads will continue to increase,

however, due to the continued growth of the

GA sector. Between 1970 and 1980, GA traffic

accounted for 72 percent of the increase in IFR

tower operations and 62 percent of the increase

in en route operations. GA aircraft, particularly

turboprop and jet business aircraft, can be expected to generate about 65 percent of the increase in these FAA workloads between 1980

and 1990. By 1990, business aircraft will account for about half of all demand for ATC

services.

The future growth of air traffic will aggravate

congestion problems and spread them to additional airports. —Unconstrained growth of operations at major hubs would lead to serious

congestion at anywhere from 20 to 5O airports

by 2000, depending on economic growth rates,

compared to 5 or 10 airports before the 1981

strike. Unless there are capacity increases to relieve congestion at major hubs, there will be

a redistribution of air carrier operations to “second-tier” hubs and increased diversion of GA

traffic to reliever airports. Such a redistribution is already in progress as a result of market

forces and FAA traffic restrictions at 22 congested hubs.

The principal constraint on the future growth

of aviation will be the lack of airport capacity.

—Major improvements to increase capacity in

congested hubs—new runways or new airports

●

●

—are unlikely in the near future due to high

cost, lack of land, and community resistance

to airport noise. The principal opportunities for

capacity expansion will come at second-tier airports and at GA and reliever airports that can

accommodate traffic diverted from congested

air carrier airports. However, the construction

of independent, IFR-equipped “stub” runways

to separate slower GA and commuter aircraft

from larger jet aircraft could significantly increase the volume of traffic that can be handled at some large air carrier airports.

There are three basic forms of response to airport and airspace capacity problems: technological, economic, and regulatory. —Changes in

ATC technology and procedures can produce

small increases in capacity by allowing airspace

and runways to be utilized more efficiently.

However, the major increases to be derived

from technology will not be realized until advanced systems such as automated metering

and spacing; microwave landing system; and

wake vortex detection, prediction, or reduction

are developed and deployed by the end of this

decade or later. In the interim, congested airports will have to make use of demand-management alternatives—including economic measures such as peak-hour pricing and regulatory

measures such as slot-allocation quotas or access restrictions—in order to shift traffic to a

place or time when it can be handled more effectively.

All three approaches will be used, and the combination or emphasis will reflect both local conditions and a more fundamental policy decision:

can the Nation continue its past practice of accommodating aviation growth wherever and

whenever it occurs, regardless of the cost; or

is growth to be managed and directed so as to

make economical use of existing resources and

capacity.
THE 1982 NATIONAL AIRSPACE

SYSTEM PLAN

GENERAL COMMENTS

The stated objectives of the 1982 NAS Plan are

to achieve a significantly safer and more efficient

national airspace system over the next 20 years,

while constraining costs incurred by the Government and airspace users. The Plan attempts to integrate the various improvements to the ATC system into a single long-range program, while eliminating major deficiencies and costs of the current

system.

Viewed on this high level—as a statement of

policies, goals, and directions—the Plan is to be

commended as a significant and even bold step

compared to previous FAA efforts to chart a

future course for the ATC system. It provides a

statement of objectives and the rationale for the

proposed program of system improvements. The

Plan identifies capital investments needed to modernize and consolidate ATC facilities in order to

meet future demand and to reduce operating and

maintenance costs. The document reflects a conscious effort to provide improved services to airspace users, to promote system efficiency, and to

minimize costs both to those who fly and to the

FAA. This is a marked improvement over previous NAS Plans, which have tended to be little

more than catalogs of proposed new equipment

and engineering changes. But is is not without

faults.

ADDRESSING FUTURE REQUIREMENTS

The needs of civil aviation represent what one

participant in the OTA’S Conference called a

“three-legged stool, ” made up of airports and terminal area airspace, rules and procedures, and

ATC technology. All three areas need to be addressed in a timely and coordinated manner.

The NAS Plan itself acknowledges that “capacity limitations at busy airports will be the constraining element” in the system, yet it fails to address solutions to airport capacity problems and

devotes only 12 of its 450 pages to the place of

airports in the NAS. A new version of FAA’s National Airport System Plan is expected to be released in the fall of 1982, and there is concern that,

as in the past, it will be an uncoordinated catalog

of State and regional plans. FAA has programs

under way to identify and evaluate techniques for

increasing airport capacity, and it would be desirable for FAA to integrate its plans for future

airport development with those for ATC facilities

and equipment.

In cooperation with airspace users, FAA has

also begun a National Airspace Review (NAR) to

study possible changes in ATC procedures and

flight regulations. Changes in ATC procedures

(like changes in airport plans) could have a profound effect on ATC requirements, and coordination between NAR and the plan for equipment

modernization is vital. NAR has just begun and

will take 42 months to complete, and by then FAA

may have made a commitment to many of the

equipment changes outlined in the NAS Plan.

There is a recognized need for improvements

in the ATC system and, given the long leadtimes

involved, these improvements should be set in

motion as soon as possible. As a practical matter, FAA needs a long-term modernization plan—

complete with a long-term approach to funding—

to ensure that the plan can be carried out. However, this requires a realistic sense of both the requirements that will be placed on the system by

future growth and the opportunities that will be

available in computer and telecommunication

technology, as well as sufficient flexibility to exploit those opportunities in order to meet those

requirements.

9
10 ● Review of the FAA 19&J National Airspace System P/an

Because it attempts to fit all the new technological elements into a coherent system framework,

the FAA considers the current NAS Plan a “blueprint” for future system evolution, indicating the

steps that will be required and when they will be

carried out. The Plan, however, is not a full and

specific description of system development, acquisition, and deployment—nor is it really intended

to be. Important details of engineering and testing

for each subsystem remain to be set forth in technical documents scheduled for issue in the coming months. The Plan should thus be viewed as

only the apex of a pyramid of plans and specifications for new equipment and facilities.

Within these limitations, the ATC system improvements proposed by FAA are technologically feasible and desirable with respect to safety,

capacity, and productivity. Nevertheless, there

are alternatives that might be equally effective

and, given the uncertainties in FAA’s traffic and

demand forecasts, it would be prudent to adopt

an implementation schedule that neither forecloses

potential options nor constrains the final system

design. FAA’s proposed en route computer replacement program in particular has been criticized on this score. The Plan requires the coordination of many disparate projects, many involving considerable technical or schedule risks, yet

it lacks a clear statement of priorities and provides

no alternatives or contingencies in the event of

problems, delays, or budget constraints.

PRIORITIES

While the 1982 NAS Plan states the goals that

will guide the development process, it does not

relate these goals to specific programs in a systematic fashion. Presumably there is a hierarchy

among goals and among programs that will contribute to achieving these goals, but nowhere in

the Plan are these priorities delineated. If, because

of budgetary constraints or failure to meet engineering objectives, there are items that must be

eliminated or schedules that must be altered, the

Plan does not make clear what effects this would

have on the development of the system as a

whole. Nor is it made explicit how elements of

the Plan could be eliminated or rescheduled in

such a way that major objectives are not compromised.

planning process and describing the steps that

FAA went through to identify requirements, analyze options, and lay out a course of action. It

might be hoped that FAA will carry this explanation one step further by describing the logical dependencies among elements of the Plan—i.e., an

explanation of how each element supports others

and how they contribute to particular objectives.

The Plan is replete with development flow diagrams for each level of the system, but these charts

show little more than the temporal sequence of

events, the merging of development streams over

time. The diagrams, and the accompanying text,

do not indicate critical paths and the specific relationships to safety, capacity, and productivity.

A valuable feature of the Plan is material in the

introductory chapter stating the rationale of the

SCHEDULE

A major shortcoming of the Plan as a planning FAA’s approach seems to be to implement the endocument is that the development and deploy- tire plan as expeditiously as possible to prevent

ment schedule is not tied directly to specific com- the ATC system from being overwhelmed by

ponents of aviation growth or to the needs for growing demand. However, as FAA’s own foreparticular services at certain times and places. casts indicate, growth is expected to occur at dif-
The 1982 National Airspace System Plan ● 11

ferent rates in different regions and among user

groups. This pattern of growth may impose requirements not addressed by the NAS Plan.

For example, the Plan states that the major factor constraining the future growth of aviation will

be the lack of capacity at major airports. Yet, the

first part of the ATC system scheduled for modernization and increased capacity to handle traffic is the en route system. Terminal area improvements, some of which could ease airport capacity constraints, are not planned for installation

until the 1990’s. Giving priority to improvements

that would increase the throughput of en route

centers does not seem entirely consistent with the

forecasts of where the capacity of the system will

be most severely limited. There is little apparent

advantage in moving en route traffic more expeditiously only to have it encounter delays in terminal areas where capacity improvements are not

scheduled to be made until the early 1990’s.

FAA has also set itself a complex task of system

development and deployment—more complex

than any it has attempted before—and there is

room for doubt about the prospects of keeping

to the time line laid down in the Plan, especially

since there are so many elements and paths of development that must be coordinated.

En route automation, for example, involves two

major procurements—the rehost computer, and

then new software and sector suites. FAA’s proposed strategy is a complicated process that involves selecting from all competitors two “finalists” for each of the two major procurements.

These finalists will then be asked to demonstrate

their proposed system at the Test Center in Atlantic City, after which a production contract will

be awarded to one of each pair.

For just one of the many NAS Plan programs,

therefore, FAA is placing itself in a position where

it must manage four major contractor efforts at

the same time. The work of these contractors, and

possibly several subcontractors, must be coordinated and kept on schedule. Equally important,

the contractors must be kept insulated from each

other to preserve competition and protect proprietary information. A less complicated strategy

might have better chances of success, given the

management problems inherent in this approach.

If FAA concludes that its proposed approach of

directing four contracts at one time is to be preferred, then—as a minimum—the agency should

take additional steps to increase its internal

capability in the area of systems acquisition

management and should plan to strengthen the

role of an outside system integration contractor.

FAA recognizes this need and has recently announced internal management changes to improve

these capabilities.

In the face of the uncertainties about future

growth, and in view of the difficulties of keeping

the parts of a complex development program on

schedule, it is surprising that the 1982 NAS Plan

does not deal explicitly with contingencies or the

effects of schedule slippage. No endeavor of this

scope and complexity can reasonably be expected

to adhere to a nominal schedule. There are inevitable engineering problems; delays will occur even

with the best of management; unforeseen circumstances will arise. One participant in the OTA

working group on computer and communication

technologies characterized the schedule as a “noproblems scenario, ” admirable for its conception

but not realistic in view of the manifold implementation problems that might be encountered. *

*As this report was being prepared for publication, the General

Accounting Office released its review of the NAS Plan (Examination of the Federal Aviation Administration’s Plan for the National

Airspace System—Interim Report, AFh4D-82-66, Apr. 20, 1982).

GAO’s findings very closely parallel OTA’S on several major points.

They found that the NAS Plan lacks the detail and justification usually needed for budgetary approval and implementation. They also

found that FAA’s proposed en route computer replacement strategy

poses both short-term and long-term risks, and they advise that FAA

consider less risky alternatives—among them conversion of 9020As

to 9020Ds. GAO points out that FAA has not yet developed a careful

and detailed transition plan, which is essential to an effort of this

magnitude and complexity. Finally, GAO raises questions about

FM management and adminstrative resources and advises FAA to

strengthen its capability in this area as a matter of first priority.
FAA AVIATION FORECASTS

Accommodating the anticipated growth of air

traffic and ATC workloads has been a primary

justification for proposed system improvements.

In the past, however, FAA’s long-term forecasts

have generally proven to be too high. This raises

questions about the usefulness of FAA’s traffic and

workload forecasts for 10 years and beyond as

a guide to long-range planning and investment

decisions. For example, FAA forecasts the onset

of delay problems by the late 1980’s. This forecast

underlies the proposed approach to en route computer replacement, a decision that sets the pace

and direction for overall system modernization.

That decision, if taken, may unjustifiably limit

the options available for the final system design.

OTA’S review indicates that the growth projected by FAA may well ultimately occur, but

there is sufficient uncertainty about near-term

growth that any program for upgrading the system should emphasize a design that can be

adapted to less growth (or more growth) without

a fundamental change in the system. Questions

about the accuracy and usefulness of FAA aviation forecasts stem from three principal concerns:

●

●

●

historical accuracy of FAA forecasts;

forecasting methodology used by FAA, including the ability of FAA forecasts to account for noneconomic influences on aviation growth;

specific assumptions underlying the forecasts

on which the 1982 NAS Plan is based.

ACCURACY OF PAST FORECASTS

Recent FAA forecasts of air traffic and ATC

workloads have tended to be much higher than

actual results. After underestimating growth in

the early 1960’s, the long-range (lO-year) projections for the past 15 years have consistently been

too high, often by 50 percent or more. Figures 1,

2,and 3 compare past forecasts with actual workloads at FAA towers, en route centers, and flight

service stations. They show that the workloads

originally projected for fiscal year 1981 (in 1970)

were between 50 and 180 percent higher than what

actually occurred. Alternatively, one could conclude that the forecasts were off by a decade since

the levels of demand once predicted for 1981 are

now expected in the 1990’s or later. FAA nevertheless believes the current forecasts to be sufficiently accurate that they can serve as the basis

for planning long-term system improvements.

Analysis by the Congressional Budget Office

(CBO) of the accuracy of FAA forecasts shows

a similar pattern (table 1). Five-year forecasts of

tower operations made during 1959-65 for the

years 1964-69 averaged 19 percent too low, while

the 1966-73 projections for the years 1971-78 averaged almost 33 percent too high. Starting in 1974,

FAA initiated a new and much improved econometric methodology for forecasting passenger enplanements and revenue passenger miles (RPMs),

and the accuracy of these projections has subsequently improved.

However, ATC workloads are driven not by

enplanements or RPMs but rather by operations

—takeoffs and landings—and the 1974-76 projections of total tower operations for 1979-81 remained too high by an average of over 21 percent. Forecasts of total instrument operations at

FAA towered airports—a more useful indicator

of ATC workloads—have been somewhat more

accurate, as have forecasts of IFR aircraft handled by en route centers. Flight Service Station

workload projections have been the least accurate

of the relevant forecasts.

73
14 ● Review of the FAA 1962 Nationa/ Airspace System Plan

Figure l.— FAA Tower Workload, Actual and Forecast, 1960-2000

70

50

40

30

20

10

0

1960 1965 1970 1975 1980

Year

1985 1990 1995 2000

SOURCE: Office of Technology Assessment, from FAA data,
FAA Aviation Forecasts ● 1 5

I

I

*198”

*198 0

1960 1965 1970 1975 1980 1985 1990 1995 2000

Figure 3.–FAA Flight Service Workload, Actual and Forecast, 1960-2000

401-

. , - ”

10

t

I I I I

1960 1965 1970 1975

I

i

I

I

I

I

I

I
16 ● Review of the FAA 1982 National Airspace System Plan

Table 1 .—FAA Forecasts Compared With Actual Data (percentage difference)

Total Total Itinerant IFR

commercial revenue Hours flown GA operations Total Instrument aircraft

Forecast For air carrier passenger in general operations at FAA operations operations handled at

year the year enplanements miles aviation at FAA towers towers at FAA towers at FAA towers FAA ARTCCS

1959 1964 – 1.3 – 6.5 – 0,6 4.6 6.0 9.7 – 4.8 11.7

1980 1985 – 9.5 – 9.7 – 1.2 –27.8 – 12.7 –21.6 0.3 – 12.8

1961 1966 –27.5 –26.0 – 15.3 –37.7 –20.0 –28.9 –28.0 – 14.8

1982 1987 –32.1 –31.4 –23.6 –34.7 –20.6 –27.3 –25.6 – 19.2

1963 1988 –41 .3 –41.3 N/A –38.4 –26.9 –32.5 –41 .8 –24.5

1964 1989 –31 .4 –33.6 –23.5 –27.3 –24.0 –24.9 –31.7 –23.8

1985 1970 – 14.1 – 19.8 – 16.3 – 2.6 – 8.0 – 5.2 – 16.0 – 11.7

1966 1971 9.4 0,5 – 1,6 53,7 32.4 42.2 0.6 – 1.4

1967 1972 23.6 13.0 9.1 72.5 43.8 54.9 22.7 25.5

1988 1973 23.9 15.9 7.4 78,3 49.7 58.4 18.2 19.7

1969 1974 21.1 21.2 4.6 53.6 37.7 42.4 – 2.1 22.7

1970 1975 26.3 33.0 – 0.6 60.9 19.7 25.9 – 15.6

1971

15.3

1976 19.0 28.6 – 0.6 42.9 14.1 22.9 – 16.4 9.2

1972 1977 22.3 33.7 – 6.8 36.9 4.5 – 2.0

1973

11.2

1978 14.0 18.3 – 10.4 14.8 ; : : 8.8 – 3.6 – 0.7

1974 1979 – 9.7 – 7.4 – 13.7 11.8 2.2 9.4 – 2.2 – 2.7

1975 1980 – 10.6 – 17.3 – 0.2 34.6 15.6 25.7 – 7.1 – 3.7

1976 1981 4.3 – 1.8 15.7 41.3 24.3 32.1 4.6 4.8

SOURCE: Congressional Budget Office, from FAA Aviation Forecasts, 1959 to 1976.

FORECAST METHODOLOGY

CBO’s analysis of FAA forecasting models identified several methodological features that may

account for at least part of the inaccuracy of

FAA’s forecasts. As noted earlier, the econometric

models used to project enplanements and RPMs

have proven to be far more accurate in recent

forecasts. However, the methods for translating

enplanements and RPMs into projected operations

—based on assumptions about average load factor, aircraft size, and stage length—appear to be

far less sophisticated. FAA’s 5-year forecasts of

air carrier enplanements have been off by only

about 1 percent since 1974, while projected operations have been more than 20 percent too high.

This discrepancy is explained in part by airlines

using larger aircraft, with higher load factors, on

longer routes. *

Another likely cause of error in forecasts of

operations is the methodology FAA uses for projecting GA fleet size, operations, and resulting

ATC workloads. In the FAA model, changes in

the projected size of the GA fleet are driven primarily by changes in the gross national product

(GNP) and to a lesser degree by aircraft prices and

*This difficulty is not unique to FAA. Boeing and others cite problems in anticipating airline route structure and load factors as a source

of error in their forecasts.

interest rates. Changes in fuel prices, however,

are implicitly assumed to have no measurable effect on the growth of the GA fleet. This omission

has a strong influence on the resulting forecasts

of workloads imposed on the ATC system by the

GA sector, because fleet size is the only causal

variable used in projecting GA instrument operations at FAA towers. Likewise, forecasts of local

and itinerant GA operations, as well as GA demand for flight services, are driven primarily by

fleet size and only to a much smaller extent by

fuel price or other variables. A number of other

judgments clearly enter into these calculations, but

they are not explicitly made, and their influence

on the results is unclear.

These questions about GA forecasting methodology have an important bearing on overall

system planning and investment, because so much

of the anticipated growth in ATC demand is expected to come from the GA sector. FAA forecasts

that the GA fleet will grow by 50 percent between

1980 and 1990, and that during the 1980’s GA aircraft will account for 65 percent of the increased

workloads at FAA towers and en route centers,

and 75 percent of the increase in flight services.

Yet the size of the GA fleet is assumed to be driven

almost entirely by growth in GNP and personal
income, with little or no allowance for saturation

in this market—a potential problem in forecasts

covering 10 or 20 years. This also raises questions

about the economic projections and other assumptions underlying the aviation forecasts on which

the 20-year investment program of the NAS Plan

is based.

GROWTH ASSUMPTIONS IN THE 1982 NAS PLAN

Economic assumptions, particularly about highly aggregate variables such as GNP and disposable

personal income, are the principal drivers in

FAA’s forecasts, and the projections are very sensitive to changes in long-term growth rates. Past

FAA forecasts included three or four alternative

scenarios to allow for the uncertainties of future

economic growth, with the “baseline” scenario

being the most likely foreseeable outcome. These

scenarios were previously based on economic indicators prepared by Wharton Econometric Forecasting Associates using their Long-Term Industry

and Economic Forecasting Model. Between 1976

and 1981, the range of these scenarios became

both wider and lower, indicating greater uncertainty about future trends and less optimism about

the probability of continued rapid growth.

In the September 1981 forecasts, however, the

baseline scenario was based on economic projections supplied by the Office of Management and

Budget (OMB). These OMB projections were later

withdrawn and, due to uncertainties caused by

the Professional Air Traffic Controllers Organization (PATCO) strike, the resulting FAA forecasts

were also discarded before publication—’’sent to

the shredders instead of the printers, ” in the words

of FAA’s Director of Aviation Policy and Plans.

Revised 1981 aviation forecasts based on new

OMB economic projections were not released until

February 1982; the NAS Plan itself is based on

FAA’s 1980 forecasts and Wharton’s March 1980

economic projections, which do not reflect recent

changes in aviation and the general economy.

These economic forecasts and aviation growth

projections were the subject of considerable criticism by aviation experts during OTA’S review of

the 1982 NAS Plan. Several members of Working Group No. 1 observed that the administration’s numbers should be considered “targets”

rather than projections. Compared to Wharton’s,

they tend to show higher growth rates for GNP,

and lower growth rates for inflation and fuel

prices, resulting in a higher long-term growth rate

for air traffic. Some participants questioned whether aviation could in fact continue to grow as fast

as it had in the 1970’s, given the current financial

plight of the airlines and the recent softening of

the GA market. While disagreeing with FAA’s

short-term projections, however, they recognized

the danger of allowing long-term forecasts to be

overly influenced by current economic conditions.

CONSTRAINTS ON FUTURE GROWTH

FAA’s mission to foster civil aviation creates

a planning process that naturally avoids the risk

of imposing fundamental constraints on the

growth of air traffic. It may even be better for

FAA to err on the high side rather than the low

side, although such predictions may become selffulfilling prophecies to the extent that providing

additional services begets additional demand. As

a result, FAA’s forecasts are unconstrained—they

assume that past trends will continue, that there

will be no limits imposed on growth, and that the

proposed improvements will be made when and

where needed to accommodate growth. But there

are a number of factors other than the ATC system itself that could change these trends or restrict

future growth. These events and influences, most

of which are neither accounted for in FAA forecasts nor addressed in the 1982 NAS Plan, include

the following:

● Airports. —The NAS Plan recognizes that

congestion at major hubs and relievers is a
18 ● Review of the FAA 1982 National Airspace System Plan

●

●

cause of special concern, but the availability of GA airports will also be a widespread

and serious constraint on growth. Although

there has been a net increase in the overall

number of airports in the last 15 years, over

300 GA airports have been closed or abandoned each year since 1965 and there has

been a steady shift toward privately owned,

private-use airports. The result, particularly in metropolitan areas, is a decrease in the

number of public-use landing places and

growing inconvenience in owning an aircraft.

Both factors will influence the growth of general aviation. “One way to test the realism

of doubling the fleet, ” according to one aviation consultant, “is to try to figure out where

they’re going to put them with the present

trend in runways, ramps, and tiedowns. ”

Fuel Price. —The greatest uncertainty facing

domestic aviation in both the short and long

term is the future price and availability of

aviation fuels. This uncertainty can cause

sudden shifts in FAA forecasts: those in the

1982 NAS Plan (based on September 1980

data) assume an average real increase in fuel

prices of 3 percent per year through 1993,

while the revised 1981 FAA forecasts (released in February 1982) assume real decreases during 1982-83 and an average real

increase of only 1 percent per year during

1984-93. No long-term shortage is anticipated

in either forecast. The current “oil glut” and

price decreases may be transient events, however. In addition, there are indications that

aviation gasoline (used by smaller pistonengine GA aircraft) may become increasingly

difficult to obtain; more likely to reduce personal GA than the business, corporate or airtaxi operations that place more demand on

the ATC system.

User Fees. —The 1982 NAS Plan indicates

that the cost of upgrading the ATC system

will be borne by the users, but the 1980 traffic forecasts on which the NAS Plan is based

do not reflect the administration’s user fee

proposals. Sudden large increases in fuel

taxes could depress traffic, a situation the

proposed “escalator” schedule is designed to

avoid. Nevertheless, cost recovery through

●

●

user fees could affect both the demand and

the funding for planned system improvements.

Many experts feel that previous user fees

had a small restraining effect on GA growth

in the 1970's and that the original administration proposal of a $.65/gallon tax on GA jet

fuel would have had a dramatic effect on use

of the system by business aircraft. The current user fee proposals will have less effect

on precisely that part of GA traffic which is

placing increasing demand on the system. As

with fuel prices, however, the FAA model is

not sufficiently sensitive to give an accurate

estimate of this effect.

Furthermore, if future traffic levels turn

out to be significantly lower than projected

by FAA, total revenues from airspace users

may also fall short of the levels required to

carry out the proposed improvements. Current FAA and OMB forecasts show steady

increases in both traffic and user fee revenues,

with user fees paying for 85 percent of total

FAA costs by 1987 (see “Cost and Funding

Issues”).

Aircraft Technology and Ftnancing. —Recent

improvements in airline productivity have

come from higher utilization and economies

of scale rather than aircraft technology, and

further improvements are likely to come

more slowly than in the last 20 years. The

development of a new generation of advanced-technology aircraft will depend on

the potential market, which in turn depends

on airline profitability. Some near-term increases in fleet efficiency could be achieved

by retrofitting existing aircraft. Airline profits are at all-time lows, however, and capital

requirements for new equipment would demand record levels of return on investment

through 1990.

Deregulation and Industry Structure. —Airline deregulation has destabilized the industry’s price and market structure, causing over

competition and low profitability that increase the risks and uncertainties of airline

financing. Some analysts feel that the demise

of some carriers may be a natural and desirable result of complete deregulation, and a
FAA Aviation Forecasts ● 1 9

●

few predict the failure of a major carrier by

mid-1982. * Restructuring of the industry

through bankruptcies or mergers might remove overcapacity, and the survivors might

be in a stronger financial and competitive

position. Termination of sections 406 and 419

subsidies in 1985 and 1988 will also affect

commuter airline profits and service to as

many as 100 small communities. These service reductions could, in turn, contribute to

an offsetting increase in business aviation.

Strike Impacts. —Traffic restrictions imposed

by FAA as a result of the PATCO strike will

continue for at least 2 years and possibly far

longer. FAA assumes that traffic will rebound

rapidly when these restriction are removed,

but adjustments made by users during this

period may permanently alter aviation

growth trends and traffic distribution. Observers have pointed out that the General

Aviation Reservation system has artificially

forced into the IFR system many GA operations that might otherwise have been outside

the system—Visual Flight Rules (VFR)—and

these users may have become accustomed to

using ATC services. Others feel that airport

slot allocation has helped major air carriers

while hindering the expansion of commuters

and new entrants. These traffic restrictions—

particularly at major hubs—might have to

be extended or reimposed in the future as a

means of addressing-airport congestion and

encouraging further redistribution of operamulate a reorganization plan acceptable to its creditors. tions to relievers and second-tier hubs.
SPECIFIC TECHNOLOGIES

The current ATC system, both in en route centers and terminal areas, is based on the technoIogy

of the 1960’s. Technology has made rapid strides

since that time, and virtually everyone believes

that the present ATC system should be upgraded

or replaced. New computer hardware, software,

and communications technologies can be used to

build an ATC system that is safer, more reliable,

and more cost effective.

The program of improvements proposed in the

1982 NAS Plan are technologically feasible and

desirable for purposes of safety, capacity, and

productivity. The foregoing analysis of FAA’s

traffic forecasts, however, raises questions about

how soon additional capacity will be required,

Furthermore, in some cases there are technological

alternatives that might serve the ends of safety

and productivity as well or better, and possibly

at less cost, than those proposed by FAA. These

alternatives merit reexamination; but, given the

long leadtimes required for the modernization

program proposed by FAA, the choices need

be studied without delay so that decisions can

reached promptly.

SYSTEM DESIGN AND TRANSITION

A key element in the 1982 NAS Plan is merger

of the present 23 en route centers and 188 terminal

control facilities into a total of 60 or fewer consolidated ATC facilities. There are differences in

ATC requirements between en route and terminal

environments, but they are not so significant that

separate and distinct systems must be maintained.

Consolidation would also allow FAA to use common hardware and software to support all ATC

activities, rather than maintaining separate but

functionally similar systems as at present. If this

also allows a move toward standard, “off the

shelf” equipment, FAA could be in a position to

move with the technology as it develops in the

future. Producers of computer and communication equipment are generally committed to providing their customers with “family” systems that

can evolve to take advantage of new technologies

as they become available.

FAA has chosen to move from the present ATC

system to the new one in a series of incremental

stages, minimizing the amount of change at each

point in the transition. The FAA Administrator

has stated that this approach minimizes risk by

limiting the number of system components affected by a given change. Many of the participants

in OTA’S general conference approved of this conservative approach, but others pointed out that

there is no risk-free way to go from the current

system to a new one. Though each step of the

FAA incremental approach involves some risk,

the overall technological risk is likely to be lower

than if the change were made in a more dramatic

way. Unfortunately, such incremental change introduces the possibility of an entirely different

kind of risk—that the hardware choices made in

the first stages might limit the options available

for the final system design. The future architecture of the system, in short, may be constrained

by the obsolete architecture of the system it

replaces. This is of particular concern with regard

to computer replacement, the first step in the plan.

Several experts have suggested that the needs

of the system would be better served if FAA kept

the present system running to meet short-term

needs, thus making it possible to design and deploy an entirely new system to meet the long-term

needs of the future. Advocates of this “cleansheet” approach agree emphatically with other experts that the present system must be replaced,

and that the first steps in this process should be

undertaken as soon as possible. However, they

also point out that any equipment acquired in the

short term would probably have to be modified,

replaced, or augmented with other computers

when the new system is deployed in the 1990’s.

Thus, they advocate decoupling short-term remedial measures from long-term replacement by

finding a cost-effective way to shore up the present system with the intent of discarding it alto21
22 ● Review of the FAA 1982 National Airspace System Plan

gether when the new system comes on line. The without either being constrained by the need for

chief advantage of the “clean-sheet” approach is compatibility with the computer system now in

that it would allow new system hardware and place.

software to be designed in an integrated fashion,

EN ROUTE COMPUTER REPLACEMENT

FAA’s plan for implementing the new en route

ATC system consists of four steps: 1) “rehosting”

the existing software in a new central processor

that “emulates” the present IBM 9020 but has

greater capacity; 2) replacing the present display

units used by controllers with new “sector suites”

compatible with the current software but containing sufficient processing capacity to assume some

ATC functions; 3) concurrent with step 2, discarding the current software for new software capable

of taking advantage of the new sector suites and

(if possible) compatible with the “host” hardware;

and 4) implementing a number of advanced functions designed to enhance the overall performance

of the ATC system. OTA’S review indicates that,

in general, this is a reasonable approach, but there

are questions about the separation of hardware

replacement from software redesign and about

FAA’s reasons for selecting this approach over

others that were considered.

The current IBM 9020 computers are unique to

FAA: none are in service elsewhere, and no

machine now in production is capable of running

the NAS software. FAA believes it has anticipated

the potential problems of rehosting this software,

and several vendors have indicated that they have

acceptable solutions. Participants in OTA’S technical Working Group No. 2 indicated, however,

that moving the existing software to a new

machine, no matter how similar to the 9020, is

more difficult than FAA indicates in the Plan. The

task can be done, given sufficient time and money,

but the schedule proposed by FAA is probably

optimistic.

FAA believes that the host computer will serve

as the hardware element of the ultimate system.

However, they do allow for the possibility that

it may have to be supplemented or replaced in

the 1990’s with yet another new computer to accommodate the new system software. Some experts feel that budgetary constraints might lead

FAA to retain the first host computer, however,

even though it proved less than ideal for the new

system. Others insist that the host computer

should be considered a “throwaway” and that the

design of the future system should not be constrained by the requirement to incorporate the

host computer selected now as an interim remedial

measure.

In January 1982, FAA submitted to Congress

an analysis of technological options for replacing the en route computer system.2 One of the options examined was replacing 9020As with 9020Ds

at 10 sites as a near-term measure to assure adequate capacity until a replacement system is designed and deployed. FAA’s analysis showed that

this option would give all 20 en route centers sufficient capacity to accommodate anticipated

growth until 1996, well after the new system is

scheduled to be deployed. FAA has demonstrated

the feasibility of this approach in replacing a

9020A with a 9020D system at the Jacksonville

center, and the option analysis report indicates

that such an upgrade could be effected at other

centers. FAA estimates that upgrading 10 installations from As to Ds could be completed by 1984

at a cost of $64 million; installing a new host computer at all 20 en route centers (as outlined in the

NAS Plan) could be completed by 1986 at a cost

of about $250 million. On several other points of

comparison—such as technological risk, constraint on future system design, and impact on

FAA’s management resources-the FAA’s January

option analysis showed A-to-D upgrade to be

superior to rehosting (see table 2).

Some participants in OTA’S technical working

group and general conference indicated that,

based on FM’s own analysis, the A-to-D upgrade

‘Federal Aviation Administration, op. cit.
Specific Technologies ● 2 3

Table 2.—Comparison of Rehosting and Upgrading 9020As to 9020Ds

Rehosting A-to-D upgrade

Description . . . . . . . . . . . . .

FAA evaluation:

Schedule . . . . . . . . . . . . .

Cost of first step . . . . . .

Total cost . . . . . . . . . . . .

Risk . . . . . . . . . . . . . . . . .

Impact on FAA

resources . . . . . . . . . .

Ability to evolve . . . . . . .

Transition impact. . . . . .

Rehost present software

on new computer, then

replace software and add

additional processors

needed for advanced

system.

Computer replacement 1986

Software replacement 1990

Full advanced system 1992

$250 million

$1.39 billion

Rehost may constrain

future system

High

Medium

High

Upgrade 9020A computers

to 9020D at 10 centers, then

replace hardware and software

in a single step, and finally

upgrade computer to advanced

system,

Computer upgrade 1984

New computer and software 1989

Full advanced system 1993

$64 million

$1.39 billion

Low

Medium

Unconstrained

Medium

SOURCE: Federal Aviation Administration, “Response to Congressional Recommendations Regarding the FAA’s En Route

Air Traffic Control Computer System,” DOT/FAA/AA -P-82-3, January 1982,

- .

option is the one that should have been selected.

It offers quick relief from capacity problems at

precisely the centers that now or will have problems, with lower risks, and at a lower cost. It also

preserves the opportunity to undertake the overall

design of a new system unencumbered by the

shortcomings of a computer capable of rehosting

the existing software. This option, they added,

was more conducive to both innovation and competition in the procurement of the new system.

A former senior IBM executive who was intimately involved in the development of the 9020 computers, told OTA that there would be few problems in converting existing 360/65s to 9020s. ’

FAA reports and FAA representatives attending

the OTA conference have expressed similar opinions.

An FAA observer at the OTA conference explained that one reason for rejecting the A to D

upgrade alternative was that the agency could not

locate a sufficient number of IBM 360/65s to carry

out upgrading at 10 centers. OTA subsequently

made inquiries of dealers in used computers and

*The 9020D system, which is a multiprocessor design unique to

FAA, is a derivative of IBM 360 series computers. Three-quarters

or more of the constituent parts of a 9020D are 360/65 components;

the remainder consists of parts from other IBM system 360 computers (notably the 360/67 model) plus some specially manufactured

assemblies. The central processing element of the 9020D, for example, is essentially three specially modified 360/65s. To replace 9020A

computers with 9020D computers at 10 centers would therefore involve acquisition and modification of 30 IBM 360/65s.

was assured that there would be little difficulty

in acquiring 35 IBM 360/65 systems over the next

6 months to a year. An inquiry to the General

Services Administration showed a total of 103

IBM 360/65s in the Federal computer inventory

as of April 6, 1982. Of these, 13 have been declared surplus and may be useable; many others

are undoubtedly used in routine data-processing

applications where they could easily be replaced

with more modern equipment. Such an exchange

would bring an immediate benefit to the Government, because the IBM 360/65 is no longer a costeffective machine at many installations, yet good

use could be made of it in the ATC application

where there is now no satisfactory alternative.

FAA sources have also raised questions about

the long-term maintainability of the 9020, but the

agency’s January 1982 report to the Senate indicated that maintainability has not been a problem

and is not anticipated to become one during the

remainder of the decade. IBM will not supply

parts for 9020 series after 1984, but this gives FAA

2 years to determine its future maintenance needs

and stockpile sufficient spare parts to last until

the new system is deployed.

Statements made by FAA since the NAS Plan

was released* indicate that the choice of the rehost

approach was based on four major considerations:

“Including remarks at the OTA conference and comments on the

preliminary draft of this report.
1.

2.

3.

4.

Ability to meet capacity needs projected for

the late 1980's. —The FAA report to Congress in January 1982 asserted that A-to-D

upgrade would also allow the projected demand for services to be met through the

mid-1990’s, or later if the demand materializes more slowly than expected.

Improved reliability and maintainability. —

The reliability of the 9020 system appears to

be more a problem of software than hardware, and since the present software would

be retained, neither approach would alleviate

this problem. Further, FAA has stated that,

with or without rehosting, it plans to procure sufficient spare parts to keep the 9020s

operating satisfactorily until the new computer system comes on line at the end of this

decade.

Ability to support productivity increases

planned under the automated en route ATC

system (AERA). —The planned productivity

increases to be realized from AERA will result mainly from software improvements not

hardware changes; but, in any event, AERA

will not be implemented until the early 1990’s

when the new computer system would be in

place under either option.

Reduced developmental risk. —The incremental rehost approach reduces some kinds

of developmental risk but—as argued above

—it introduces another kind of risk, namely that hardware choices made in the first

stages might limit the options available for

the final system design.

In short, OTA does not find these reasons—

either individually or collectively—to be persua- .

sive arguments in favor of rehosting. OTA agrees

that efforts for eventual replacement of the present system need to be pursued as vigorously and

as rapidly as possible. However, FAA has not presented convincing evidence that the selected approach—rehosting—is in fact superior to other alternatives. This is not to argue that rehosting is

unworkable or ill-advised. Rather, the point is

that FAA has not made a persuasive case and that

FAA should present a direct and detailed comparison of rehosting, A-to-D upgrading, and any

other options the FAA considers workable. This

justification is indispensable to an informed congressional review of the proposed computer replacement strategy. Such a head-to-head comparison of alternatives need not delay the overall

schedule of the NAS Plan, and it could even advance the objectives of the Plan by providing a

basis for clear understanding

where FAA is headed and how

there.

at the outset on

it proposes to get

AUTOMATION AND HUMAN FACTORS

The present ATC system is very labor-intensive the operation of a highlv automated system.

and, without significant increases in controller

productivity, the cost of operating the ATC system could rise precipitously as traffic grows. The

number of aircraft that a controller team can handle with the present system is limited, and the conventional solution to handling a larger volume of

traffic—decreasing sector size—has practical limits. FAA looks to increased automation as the

principal means of achieving higher levels of controller productivity.

AERA, which is scheduled to be implemented

in the early 1990’s, would change the role of the

controller from that of an active participant in the

control process to that of a manager who oversees

Many- of the routine decisionmaking functions

now performed by humans would be automated,

with the result that fewer controllers will be required for a given level of traffic. Elements of

AERA are now undergoing testing, and some features will be added to the existing en route software after it has been rehosted. Other functions—

those that will have the greatest impact on the role

of the controller and the character of the ATC

system—will not be implemented until the early

part of the next decade when the redesigned software has been installed. It is this latter group of

functions that may require either enhancement or

replacement of the proposed host computer in the

1990’s (see above).
Specific Technologies ● 2 5

As envisioned by FAA, AERA is designed to

increase the efficiency of airspace utilization as

well as the productivity of controllers. AERA will

also enable users to follow more fuel-efficient

flight paths and make better use of the equipment

they are now installing on their aircraft. Flight

management and navigation computers, linked to

AERA by a new communication link (Mode S),

will eventually receive and respond to flight instructions without increasing aircrew workload.

Similarly, delays in the system will be minimized

by the flow control procedures, and safety will

be enhanced because the system will provide for

the separation of IFR from VFR traffic outside terminal areas, rather than providing separation only

between IFR aircraft as is now the case.

Human factors and safety are important concerns in AERA. In a highly automated system it

might be impossible to revert to manual control

in the event of a system failure. Therefore, the

AERA concept assumes that the functions of the

future ATC system will be distributed among various elements. In the event that the main computer

at an ATC facility fails, the sector suite (acquired

during the second phase of system modernization)

will contain enough processing power to provide

at least some backup functions; other functions

will be transferred in real time to neighboring centers that remain operational.

FAA has yet to refine the AERA concept completely. The distribution of functions among the

various computer resources has not yet been determined, nor have the respective roles of human

controllers and automated systems been defined.

This task will be carried out by FAA and the contractor responsible for the design of the new system.

This point is stressed by the critics of the rehosting approach to computer replacement and those

who suggest that FAA use a “clean sheet” approach to the system design. They argue that premature acquisition of host hardware for the short

term could limit the options of the system design

contractor in the long term. This could result in

a requirement for extensive and expensive modifications of the host computers, a second wholesale

computer replacement, or (since that seems unlikely) the implementation of a system that cannot take full advantage of the available technologies and design options. None of the critics suggest that replacement be deferred, and all of them

recognize that at some point FAA must commit

to a specific design even though there will always

be a better technology available at some point in

the future. Rather, their concern is that premature

commitment to “rehosting” hardware could limit

FAA’s ability to take advantage of the best technology that is now available.

Studies of the AERA concept commissioned by

FAA have generally agreed that the proposed approach is feasible. However, one study, recently

completed by the Rand Corp., suggests that the

AERA concept may not be sound.3 The Rand

study indicates that total commitment to automation, with the controller no longer an active part

of the system, is unwarranted and could present

safety problems. It suggests that the controller will

not be sufficiently involved in the traffic situation to detect errors in the system and analyze

them in time to take effective action. As an alternative to the AERA concept, Rand suggests a

“shared control” concept in which the controller

has a more active part in the control process. In

the end, the level of automation proposed by

Rand would be very close to that proposed under

AERA, although the route to achieve that level

would be different and it might not achieve the

increases in productivity that would result from

the implementation of the FAA plan.

FAA, on the other hand, argues that it would

not be possible to achieve the incremental improvements required for the shared-control approach, and that the automated system is expected

to be more reliable than a system in which human

controllers are active participants. FAA maintains

it would be basically unsound, beyond a point,

to back up an automated system with a human

one that is less reliable.

3Robert Wesson, et al., “Scenarios for Evolution of Air Traffic

Control,” The Rand Corp., R-2698-FAA, November 1981.
26 ● Review of the FAA 1982 National Airspace System Plan

COMMUNICATION

Communication is the backbone of air traffic

control. Instructions and information vital to the

safety of flight must be communicated between

ground and air and between ATC facilities on the

ground. While the present requirement for air-toair communication is minimal, this link may assume greater importance in the future.

In the proposed plan, FAA indicates that a new

data link (Mode S) will be the primary channel

for transmitting data from the ground to the air

and between aircraft in flight. * Mode S will be

necessary to support the automated ATC system

that FAA proposes for the future and for the distribution of weather information and other data

of interest to aircraft in flight. It may also be used

to collect weather observations from appropriately instrumented aircraft as part of the real-time

weather system envisioned by FM. This data link

will also be used in TCAS, the collision avoidance

system adopted by FAA, to coordinate the maneuvers of aircraft when a possible conflict is detected.

‘At the OTA conference, a representative of FAA outlined the

differences between Mode S and the Discrete Address Beacon System (DABS) concept from which it was derived. From the point of

view of the data link, Mode S and DABS are functionally equivalent.

However, the ground facility requirement for Mode S will be considerably less costly because it does not involve transmitting maneuver

instructions to aircraft to resolve conflicts or avoid collisions. This

also means that less computer power and less complex software will

be required to handle Mode S than would have been required to

handle DABS. Mode S has nevertheless been the subject of controversy, primarily due to GA concern over the costs and airspace restrictions that would be imposed by eventual mandatory equipage (see

“Impacts on Airspace Users”).

Use of this data link will require installation of

Mode S transponders on aircraft. These transponders are also intended to improve the quality of

the surveillance data available to the ATC system.

FAA plans to extend the requirement for Mode

S equipage to all instrument flights above 6,000

ft by the end of the century, compared to 12,500

ft for the present Mode C. However, FAA expects

that most aircraft will have equipped voluntarily by that time, because of the enhanced services

that will be available only to aircraft carrying

Mode S transponders. Roughly three-fourths of

the current civilian fleet is equipped with the present Air Traffic Control Radar Beacon System

(ATCRBS) transponders, although only half this

number has the more advanced Mode C altitude

encoder.

Communication between ATC facilities on the

ground is also vital to the operation of the system,

particularly as the level of automation increases.

The 1982 NAS Plan envisions a dedicated system

to handle these communications requirements. It

was difficult to assess FAA’s proposals because

of a lack of details in the 1982 NAS Plan, but

Working Group No. 2 questioned the need for a

dedicated system. Despite the existing Federal investment in equipment and rights of way, several

participants felt that, given the current state-ofthe-art, FAA could meet its requirements by procuring needed communication services on the

open market.

COLLISION AVOIDANCE

The debate over collision-avoidance systems

has gone on for over 20 years. Collision-avoidance systems are designed to back up the separation assurance services provided by FAA and to

resolve conflicts that may occur because of system

errors. They are not designed to function as a substitute for the basic separation assurance services

supplied by ground control facilities.

During the summer of 1981, FAA adopted the

Traffic Alert Collision Avoidance System (TCAS)

as the collision avoidance system to be implemented, and it has been labeled by the Administrator as a key element of the 1982 NAS Plan.

TCAS is a totally airborne system that requires

virtually no expenditures by FAA beyond those

for the Mode S data link, which TCAS uses to
Specific Technologies ● 2 7

coordinate maneuvers between aircraft. Initially,

at least, installation of the required avionics will

be voluntary on the part of the users.

There are two variants of TCAS. TCAS I, intended for installation in small GA aircraft at minimal cost, provides information regarding the

presence of “intruder” aircraft and could be upgraded to include a display of traffic advisories

on potentially conflicting TCAS II aircraft. TCAS

II, designed for airliners and business aircraft, is

a more comprehensive system that provides a display of relative bearing and distance and presentation of a climb or descend indicator for an

avoidance maneuver. There are engineering models of both TCAS systems, although neither is

presently ready for certification and deployment.

The value of TCAS I has been challenged, since

it indicates only the presence of another aircraft

without providing data as to its relative position.

The feasibility of TCAS II has also been challenged. The present working model of TCAS 11

provides only a rather coarse indication of relative

bearing, and the high-resolution directional antenna required for a more accurate and useful TCAS

II system remains in the early stages of development. Several participants in the OTA conference

suggested that this antenna might not be available

for some time.

Representatives of the military community expressed concern to OTA about the impact of

TCAS on the military fleet, particularly on highperformance tactical aircraft. They point out that

space in these aircraft is at a premium, particularly

for the installation of avionics that do not enhance

mission capabilities or low-altitude safety. They

would therefore seek a Mode S design that can

be integrated with a military system such as JTIDS

or IFF. They also point out that the installation

of the antennas required for TCAS II could adversely affect the aerodynamic performance of

tactical aircraft. FAA representatives have suggested that the military may not be required by

the FAA to install TCAS (see “Impacts on Airspace Users”).

SATELLITE TECHNOLOGIES

Participants in OTA’S technical working group

pointed out that FAA has given very little attention to the possible role of satellites in the ATC

system. This technology has developed rapidly

over the past few years, and satellites have considerable potential not only as a communications

resource but also for use in surveillance and navigation.

FAA does envision that satellites could eventually have a role in providing ATC services to aircraft operating over land, but the agency believes

they are not yet a cost-effective alternative to

ground-based systems. There is considerably

greater potential in the short term for using satellites to provide services to aircraft operating over

large bodies of water, where only minimal services are now available.

Satellites also have the potential for improving low-altitude surveillance. There are presently no proposals to extend coverage to the ground,

but the possibility of providing this level of coverage at some point in the future does exist. The

area covered by a ground-based sensor is limited

by terrain, and it would be very expensive to provide for full coverage of U.S. airspace using

ground sensors alone. While surveillance radars

would not be mounted on satellites, ATC computers could use the Mode S data link to request

position reports and provide properly equipped

aircraft with separation services. This would be

particularly useful in resolving the problems that

arise when high-speed military aircraft on operational training missions must share low-altitude

airspace with small GA aircraft.

Satellites also have considerable potential as

aids to navigation. The military Global Positioning Satellite system is partially deployed and,

when completed, could be used to provide navigational fixes with the same level of accuracy now

afforded ground-based navigation aids. While national security considerations might limit the precision of the navigation aid provided to civil avia-
28 ● Review of the FAA 1982 National Airspace System Plan

tion, FAA omitted navigation satellites from the plans to have the essential parts of the new ATC

1982 NAS Plan on the basis of timing. The pre- system in place. Slippages in FAA’s proposed deparatory work necessary to bring civil services to ployment schedules, however, could reopen the

an operational status could not be completed be- satellite option.

fore the end of the present decade, when FAA
IMPACTS ON AIRSPACE USERS

FAA is attempting to modernize an ATC system that is nearing the upper limit of its productivity. New computer capacity and a higher leveI

of automation should enhance the system’s ability to deliver air traffic control services to those

suitably equipped. In the longer term, the AERA

functions will greatly ease the management of

long-distance, high-altitude, point-to-point flights.

Air carriers and larger business aircraft will benefit

most directly from system improvements in the

NAS plan. Military and some GA users, who may

often fly VFR for short distances or at low altitudes will also receive benefits, but they are mixed

with drawbacks as well.

The plan is written from the perspective of a

ground-based manager of the airspace. As a “user”

of its own system, FAA should gain a number of

benefits from automating and consolidating the

ATC system. Of the new functions to be added

to the en route and terminal area computers, nearly all are designed to provide better information

to the controller or to relieve him of routine

chores. Thus, these functions will enable the FAA

to do its job—provide for safe, expeditious use

of the airspace—more efficiently.

If automation and consolidation work as

planned, FAA will receive greatly increased productivity from controllers and maintenance personnel. FAA expects this will lead to an actual

decrease in the controller workforce and a leveling of operating and maintenance costs, despite

increased demand for services. It is generally

agreed that modernization will lead to avoidance

of the costs of maintaining the aging system into

the indefinite future. However, FAA has not yet

made available their basis for projecting increases

in productivity. Some observers note that the introduction of NAS Stage A automation in the early 1970’s, while it did slow the growth rate of the

controller work’ force, did not live up to FAA’s

expectations in this regard.

Users who are properly equipped and who operate at certain altitudes will begin receiving direct

benefits from the planned AERA enhancements

early in the next decade. FAA expects fuel-efficient

route planning to save users $250 million per year.

Most of these benefits would accrue to air carriers and business aviation because of their high fuel

use. In terms of more efficient operation, these

two user groups are likely to benefit most from

the full range of AERA improvements.

GENERAL AVIATION

With 214,000 aircraft, the GA fleet is two orders

of magnitude larger than the commercial fleet

(2,541). Some 79 percent of the GA fleet are single-engine aircraft, most of which rarely fly under

IFR. The automation of Flight Service Stations is

expected to provide benefits to GA users—notably, improved weather information. Small aircraft

operating under VFR would probably utilize few

of the other new ATC services.

The plan states that after 1990, aircraft will

have to be equipped with Mode S transponders

to fly above 12,500 ft. After 2000, transponders

would be required above 6,000 ft in order to receive ATC services.

For the majority of the GA fleet, operating

under VFR, the transponders will serve only to

mark their positions electronically. They will not

receive the other services available to IFR aircraft.

Though the 1982 NAS Plan makes the decision

to equip voluntary, the GA pilot who does not

have a transponder will find the volume of the

airspace available to him becoming smaller. Altitude restrictions will, according to some GA representatives, force many fliers that would prefer

VFR to fly IFR in order to avoid delays and unattractive routings or to gain access to more airports.

Owners of GA aircraft who wish to make full

use of the ATC system may want to equip with

TCAS and Microwave Landing System (MLS)

avionics. The cost of this equipment will not be

onerous for owners of multiengined business aircraft, who are generally eager to modernize their

29
30 ● Review of the FAA 1982 National Airspace System Plan

airborne electronics and avail themselves of the

full range of ATC services. However, the singleengine operator would get a relatively small return

for an avionics investment that might cost several

thousand dollars.

DEPARTMENT OF DEFENSE

The Department of Defense (DOD) is both a

major user and joint administrator of the national

airspace. Yet, the 1982 NAS Plan appears to have

been developed without prior consultation with

DOD. Concern has been expressed about the effect of planned FAA actions on the interface between military and civil ATC systems. In addition, some of the improved services that FAA

plans to provide may either be irrelevant to the

military mission or impose more costs than benefits on the military users.

DOD controls a significant amount of the airspace. DOD’s 8,000 controllers and 231 ATC facilities handle civil as well as military traffic in

their sectors, and their role has increased since last

summer’s PATCO strike. The NAS Plan does not

make clear how future upgrading and consolidation of centers and communications facilities will

affect the military role or the required compatibility between military and civil ATC systems.

The military forces also have the responsibility to defend from airborne intrusion. Some FAAowned primary radars are used for this purpose

by DOD under a joint surveillance system. FAA

plans to phase out these primary radars by 2000,

when most of the domestic fleet is expected to be

equipped with Mode S transponders. However,

primary radars will still be needed for defense surveillance, and the manner of their replacement is

not made clear in the proposed plan.

Military aviation accounts for about 20 percent

of all ATC operations in the continental United

States. (This includes ATC services provided by

military facilities for civil as well as military aircraft. ) Although the percentage of this traffic handled by FAA en route centers is small (16 percent)

on average, it is substantial in some regions. For

example, military flights account for 46 percent

of en route handles at the Albuquerque center.

The high concentration of military flights in certain regions makes it necessary for FAA to coordinate carefully with the military, since any planned

relocation of bases or training areas could greatly affect FAA’s projection of future traffic volume

at selected centers.

Military use of domestic airspace is mainly for

training missions, not point-to-point transportation. This means that high-performance aircraft

sometimes operate at low altitudes, sharing airspace with slow-moving GA aircraft operating

under VFR. See-and-avoid procedures do not

work well in these circumstances, and a recent Air

Force survey found that 87 percent of reported

near-collisions occurred at altitudes below 7,500

ft in uncontrolled airspace. At present, Flight

Service Stations (FSS) advise GA pilots of military

activity only on request, and there is no indication in the plan that an improvement of this procedure is planned as part of FSS automation.

Future FAA plans to put a “floor” of 6,000 ft on

secondary surveillance radar mean that problems

of separating military and GA traffic at low

altitudes will continue into the future. Some

means to provide radar coverage down to 1,000

or 2,000 ft would allow more military flights to

operate under IFR and to rely on ATC for separation from VFR traffic.

FAA’s plans for secondary surveillance radar

depend on aircraft being equipped with Mode S

transponders. The military services have reservations about this new avionics equipment because

it is of doubtful value to the military. Although

TCAS might have value in warning military aircraft of the proximity of other TCAS-equipped

aircraft, it will be of no value in protecting against

unequipped aircraft, as many small GA aircraft

at low altitude are likely to be. The Mode S transponder would offer some advantage to military

aircraft when they operate under IFR in the

domestic airspace, but it would in no way improve their combat capability.
Impacts on Airspace Users ● 3 1

DOD estimates the cost to equip military air- also be high. Further, TCAS has little military

craft with Mode S alone will exceed $1 billion. utility, and concern has been expressed that the

These costs, which will ultimately be borne by TCAS antenna could actually interfere with the

the general taxpayer, must be balanced against aerodynamic performance of certain tactical airwhatever benefits Mode S has for the civil system. craft.

Costs to equip military aircraft with TCAS will
—

COST AND FUNDING ISSUES

The costs of implementing the 1982 NAS Plan mates supplied by FAA and OMB, the F&E costs

over the next 5 years would lead to substantial for the period fiscal year 1983 to fiscal year 1987

increases in the FAA budget for facilities and would amount to about $5.2 billion (constant

equipment (F&E) and research, engineering, and 1982 dollars). The RE&D costs would be $942 mildevelopment (RE&D). According to budget esti- Iion (see table 3).

Table 3.–FAA Budget Estimates, Fiscal Years f983-87

Funding by fiscal year (in millions of dollars)a

A comparison of these projected costs, on an

annualized basis, with those of the period fiscal

years 1971-80 is shown in table 4. Future F&E

costs would be slightly over twice the historical

level, in constant-dollar terms; and RE&D costs

would be 50 percent higher. Cost estimates for

the NAS Plan in the years beyond 1987 have not

yet been released by FAA, but it seems likely that

annual expenditures of roughly equal magnitude

would be needed through the early 1990’s in order

to complete modernization of the ATC system,

install a new communication network, and upgrade air navigation facilities.

Although the NAS Plan does not address matters of funding directly, subsequent statements by

the administration tie implementation of the Plan

very closely to funding issues. FAA Administrator

Helms has indicated that the success of the Plan

depends heavily upon securing a long-term fundTable 4.—Past and Future FAA Expenditures

Average annual

expenditures

(millions of dollars)

Actual Projected

1971-80a

1983-87b

Facilities and equipment . . . . . . . . 463 1,038

Research, engineering, and

development. . . . . . . . . . . . . . . . . 124 188

Airport aid (ADAP). . . . . . . . . . . . . . 673 387

Operation and maintenance . . . . . 2,564 2,263

All other . . . . . . . . . . . . . . . . . . . . . . 62 44

Total . . . . . . . . . . . . . . . . . . . . . 3,886 3,920

aBased on FAA appropriations for fiscal years 1971 to 1980, converted to constant 1962 dollars.

bBased on FAA and OMB estimates.

ing commitment at the outset. The proposed

method of assuring a stable and reliable source

of funds is a system of user fees that would recover

85 percent of the FAA’s future capital and operating costs from those who receive ATC services.

This proposal is based on the general view of the

33
34 ● Review of the FAA 1982 National Airspace System Plan

administration that beneficiaries of Government

services should pay the costs incurred in providing

those services.

In essence, the system of user fees proposed by

the administration would reestablish the excise

taxes that were levied on airspace users under the

Airport and Airway Development Act of 1970,

which expired at the end of fiscal year 1980. The

current proposal would reauthorize revenue deposits to the Airport and Airway Trust Fund and

institute the following user fees:

● 8 percent passenger ticket tax;

● 5 percent freight waybill tax;

● $3. 00 international departure tax;

● general aviation gasoline tax of $.12/gallon

for fiscal year 1982-83 and rising thereafter

at $.02/year until reaching $.20/gallon in fiscal

year 1987; and

● general aviation jet fuel tax of 140/gallon for

fiscal year 1982-83 rising at 2@/year to 22Q/

gallon by 1987.

Initial OMB estimates, published in February

1982, indicated that these tax schedules would

lead, by 1987, to full recovery of the 85-percent

share of FAA costs allocated to civil aviation.4

Later figures released by FAA and OMB in April

1982 contained an increase of about $2 billion in

projected FAA expenditures related to the NAS

Plan for the period fiscal years 1983-87.5 However, it was estimated that 85-percent cost recovery could still be achieved by the proposed taxes

if coupled with a drawdown of about $2.2 billion

from the uncommitted balance in the Airport and

Airways Trust Fund (table 5).

4Major Themes and Additional Budget Details, FY 1983 (Washington, D. C.: Office of Management and Budget, Feb. 8, 1982), pp.

228-229.

‘Estimates presented by FAA Administrator Helms to the Transportation Subcommittee of the House Committee on Appropriations, Apr. 20, 1982.

Table 5.—FAA Budget and Cost Recovery, Fiscal Years 1983.87

Current dollars by fiscal years (in millions)

1983 1984 1985 1986 1987 1983-87

Budget authorit y

. . ..............3,904 4,760 4,806 4,655 4,704 22,829

User fee revenues:b

Current law . . . . . . . . . . . . . . . . . . . 1,474 1,670 1,878 2,108 2,344 9,474

Proposed increases. . . . . . . . . . . . 1,187 1,350 1,548 1,742 1,946 7,773

Total. . . . . . . . . . . . . . . . . . . . . .. 2,661 3,020 3,426 3,850 4,290 17,247

Trust Fund drawdown. . . . . . . . . . . . 657 1,026 659 107 (292)’ 2,157

Cost recovery (percent):

Current law . . . . . . . . . . . . . . . . . . . 38 35 39 45 50 41

With proposed increases . . . . . . . 68 63 71 83 91 75

With trust fund drawdown

(return) . . . . . . . . . . . . . . . . . . . . . 85 85 85 85 85 85

SOURCES: a FAA and OMB estimates presented to Transportation Subcommittee, House Committee on Appropriations, Apr.

20, 1982.

bOMB ,, Major Themes and Additional Budget Details, Fiscal year 1983” February 1982

cReturn to Trust Fund.

COST ALLOCATION

A more detailed analysis of the cost recovery percent of the share of costs allocated to them by

from proposed user fees (shown in table 6) indi- FAA. The proportion recovered from GA users

cates that the burden of costs recovered would would be between 12 and 20 percent of their allonot fall equally on each class of airspace user. The cated share. Thus, GA would receive a substancosts recovered from air carriers through the pas- tial cross-subsidy from airline passengers and shipsenger ticket tax, international departure tax, and pers of air freight. Within GA, the principal benefreight waybill tax would vary from 104 to 148 ficiaries of this cross-subsidy would be that part
Table 6.—Cost Recovery Under the Administration’s Proposed User Fees

(in millions of dollars)

Fiscal year

1983 1984 1985 1986 1987 1983-87

Air carrier share

(58 percent of FAA costs):

Allocated share under

FAA-proposed budget . .........2,264 2,761 2,787 2,700 2,728 13,240

Revenue under proposed

user feesa . . . . . . . . . . . . . . . . . . . . 2,530 2,863 3,237 3,631 4,035 16,296

Cost recovery (percent). . . . . . . . . . . 112 104 116 134 148 123

Generail aviation share

(27 percent of FAA costs):

Allocated share under

FAA-proposed budget . . . . . . . . . . 1,054 1,285 1,298 1,257 1,270 6,164

Revenue under proposed

user feesb 

. . . . . . . . . . . . . . . . . . . . 131 157 189 219 255 951

Cost recovery (percent). . . . . . . . . . . 12 12 15 17 20 15

Total cost recovery from

civil aviation (percent). . . . . . . . . 68 63 71 83 91 76

aMade up of 8 percent ticket tax(air carriers and Cornrnuters), 5 percent freight waybill tax, and $3 international departure ‘ax

bMade up of taxes on gasoline and jet fuel.

SOURCES: OMB, “Major Themes and Additional Budget Details, Fiscal Year 1983,” February 1982. FAA estimates presented

to Transportation Subcommittee, House Committee on Appropriation, Apr. 20, 1982.

of the business and corporate aircraft fleet consisting of turboprop and turbojet aircraft. These aircraft, which now number about 7,600, or twice

the air carrier fleet, operate in the ATC system

much of the time and are used in a manner similar

to air carriers-point-to-point flights, into and out

of major airports, under IFR, and receiving full

ATC services. The business and corporate aircraft

segment now constitutes about 60 percent of all

GA traffic that uses the IFR system and represents

30 to 35 percent of the total workload at FAA

towers and en route centers. By the early 1990’s,

FAA projects that GA turboprops and turbojets

will make up about 45 percent of the ATC facility workload. (Air carriers will make up 30 percent, other GA 15 percent, and military 10

percent. )

The administration advocates full recovery of

allocated costs from each class of airspace user

as a principle of taxation. However, even allowing for the imprecision of the methodology of cost

allocation and revenue projection, the user fees

proposed by the administration do not accomplish

parity of cost recovery. A passenger ticket tax of

6.5 percent, not the proposed 8 percent, would

be sufficient to produce full recovery of the commercial aviation share. For GA to pay a share

roughly proportionate to the burden it places on

FAA facilities, the combined gasoline and jet fuel

taxes would have to be five to six times higher

than the current administration proposal. Organizations of general aircraft owners and manufacturers point out that such an increase, even if

phased in over several years, would have a severely depressing effect on the use and purchase of

GA aircraft.

The administration’s proposal is likely to be

contested by airspace users on several grounds.

First, there is strong disagreement by civil aviation groups about what share of FAA costs should

be allocated to users and what share should be

treated as a general public benefit. Their contention is that the 85-percent share allocated to users

is excessive because the public benefit of the National Airspace System is much higher than 15

percent—perhaps more on the order of 20 to 30

percent if one includes the general benefits of the

air transportation system. Thus, they would argue

for cost recovery from civil users of roughly 70

to 75 percent of FAA costs—not the 85 percent

assumed in the current administration proposal.

Second, there is also dispute about the allocation of costs between commercial and general aviation. The owners and operators of small propellor aircraft weighing under 12,500 lb contend that
they make very little use of the IFR system and

therefore should be charged only for the lesser

services they receive under VFR. * The 1978 cost

allocation study by FAA took the small aircraft

owners’ position into account and offered an alternative cost allocation scheme (called the “minimum services method”) that reduced the overall

GA share to 13 percent with the balance allocated

to the general public as society’s cost of maintaining a safe national airspace system. b

While business and corporate aircraft operators

generally oppose the concept of differential taxation based on their more extensive use of the IFR

system, it is precisely this small percentage of the

GA fleet that is responsible for the largest projected increase in the demand for ATC services.

The turbine-powered portion of the GA fleet, vir-

● The Aircraft Owners and Pilots Association, for instance, estimates that only 5 percent of the GA flights are under IFR and that

the average flight time for GA aircraft that do fly IFR is roughly

30 minutes, compared with 1 hour 23 minutes for air carriers.

b

Financihg the Airport and Airway System: Cost Allocation and

Recovery, FAA-AW-78-14 (Washington, D. C.: Federal Aviation

Administration, November 1978).

tually all of which are flown for business purposes, is forecast by FAA to grow from 7,600 to

15,700 planes by 1993. The growth of business

aviation activity is primarily responsible for GA

projections of near-term capacity problems at en

route centers.

If equitable cost recovery is to be the principle, a cost allocation formula should take into account significant differences in the burden placed

on the ATC system by the various segments of

the GA fleet. The administration proposal does

not do so, except that the tax on jet fuel is 2a/

gallon higher than the tax on aviation gasoline.

In selecting the proposed scheme, the administration seems to be hewing close to the system of taxation that existed under the previous Airport and

Airway Development Act, taxes which are familiar and generally acceptable to the civil aviation

community. The alternative of seeking to resolve

the issue of cost recovery in a more equitable, but

less familiar way, would likely make the administration’s proposed user fees even more controversial.

ALTERNATIVE METHODS OF TAXATION

Other methods of levying user charges are possible: either fees based on the actual use made of

the ATC system or an annual tax based on aircraft characteristics and avionics equipment.7

Participants in the OTA Conference on the National Airspace System Plan flatly ruled out direct

user charges as unworkable. OTA does not agree.

By means of the present ATCRBS transponder it

is possible to identify uniquely each aircraft using

the ATC system, continuously monitoring each

plane from takeoff to landing. This capability

would be enhanced by the future Mode S transponder. The data generated by either of these

transponder systems could provide the Government with a detailed record of the services received by each aircraft. Owners could then be

billed for what they used.

Toll roads provide a rough analogy. Charges

on those highways are usually based on the disThese alternatives are discussed inch. 7 of the OTA report, Airport and Air Traffic Control System, OTA-STI-175, January 1982.

tance traveled and the number of axles on the vehicle, a factor which approximates the burden

placed on the road surface by vehicle weight. Data

generated by the ATCRBS or Mode S transponders could conceivably provide the FAA with a

record of the time each transponder-equipped aircraft is in the system. From that information, FAA

might develop a basis for “toll charges” and collections. Computers now make it possible for persons to make a call from any of the 170 million

telephones in the United States and to pay for the

charges on their own phone bill a month later.

Social Security mails monthly checks to over 35

million recipients, either directly or to their banks.

So, before some form of direct billing is completely ruled out, FAA should determine whether the

modern technology of transponders and computers could be utilized to make direct user fees a

practical alternative to excise taxes.

Another possible mechanism for levying user

charges is a yearly tax on aircraft by weight, number of engines, or avionics equipment. The price
Cost and Funding Issues w 37

of admission to the future ATC System will be

sophisticated avionics (Mode S, TCAS, MLS) to

complement the ground-based system. Taxing that

equipment could provide FAA with an alternative

means of financing ATC services.

While the idea merits further inquiry, there are

at least two concerns to be overcome. First, a tax

on avionics equipment would not be a tax on avionics use. The charge would be the same whether

an airplane flew 200 or 2,000 hours a year and

whether it used the advanced equipment or not.

From the user’s point of view, there would be no

direct link between services received and taxes

paid. Still, it is not unreasonable to assume that

aircraft carrying certain avionics will make use

of that equipment to receive ATC services and,

hence, that a tax on avionics would be an economically efficient way to recover the costs of providing services.

Another concern, voiced by several OTA conferees, is that raising the price of admission to the

ATC system could have a negative effect on safety. The new avionics equipment is designed to

make flying safer, and FAA hopes to induce GA

owners to equip voluntarily by offering them

more and better services. For example, weather

is a factor in about 40 percent of all fatal aircraft

accidents, and the Mode S data link is intended

to bring automated and improved weather information to GA pilots who are equipped with these

transponders. A tax that discourages avionics purchases could conceivably weaken the NAS Plan’s

principal goal: safety.

OTHER FUNDING ISSUES

There are several other issues that arise from

the proposed user fees: the negative effect of fees

on aviation growth, the disbursement of user revenues to cover operating and maintenance costs,

and the disposition of the present uncommitted

balance in the Airport and Airway Trust Fund.

The FAA’s growth forecasts form an important

part of FAA’s justification for rapid modernization and expansion of the ATC system. Increased

user fees, however, increase the price of commercial air travel and the costs to GA users. The effect of these cost increases could be to dampen

the expected growth in civil aviation, perhaps by

enough to alter significantly the forecast level of

demand for services at FAA facilities. This, in

turn, implies that ATC equipment and facilities

to service this demand may not have to be as extensive as FAA expects or that they may not be

needed as soon as now forecast. An analysis by

FAA of the relationship between user fees and aviation growth would be a valuable aid to Congress

in evaluating the proposed schedule for ATC system improvements.

The administration proposal calls for user fees

to recover 85 percent of all FAA costs, including

operation and maintenance (O&M) expenses,

which make up about 60 percent of the FAA

budget for the coming 5 years. In the past, airspace users have objected to funding O&M expenses through user fees on grounds that O&M

costs include many items not directly attributable

to operating the ATC system and that users

should not be expected to bear these costs, which

should be assigned to the general public. Figures

ranging from 25 to 50 percent of O&M costs have

been suggested by various user groups in the past

as a reasonable upper limit of their proper share.

Another objection, which pertains only to user

fees collected under the previous Airport and Airway Development Act, is that use of Trust Fund

revenues to cover O&M costs violates the basic

purpose of that Act, which was to fund capital

improvements to airports and airways. Some

users, who have opposed diversion of Trust Fund

monies to noncapital expenditures in the past,

might oppose the current Administration proposal

unless the share to be used for O&M costs were

negotiated specifically and made contingent upon

not reducing expenditures for capital purposes.

A third, and related, issue is how to spend the

present uncommitted balance of roughly $3 billion

in the Trust Fund. The administration proposal
38 ● Review of the FAA 1982 National Airspace System Plan

is to draw down this balance over the next 5 years, their full allocated share of all ATC system costs.

using it to supplement user fees in order to meet On the other hand, aviation user groups argue

85 percent of FAA expenses in all budget cate- that this would not be consistent with the purgories. This is an integral part of the overall plan pose for which the Trust Fund was established.

to put FAA funding on a base whereby users pay
PART 2

Appendixes
Appendix A

GROWTH SCENARIOS IN FAA’S

NATIONAL AIRSPACE SYSTEM PLAN

Members of Working Group 1

(February 25, 1982)

Robert W. Simpson, Chairman

Professor, Flight Transportation Laboratory

Massachusetts Institute of Technology

Samuel C. Colwell

Director, Market Planning

Fairchild Industries, Inc.

Herman Gilster

Manager, Traffic and Economic Forecasting

Boeing Commercial Airplane Co.

David Lewis

Principal Analyst, Natural Resources and

Commerce Division

Congressional Budget Office

David J. McGowan

Manager, Systems Operations

General Aviation Manufacturers Association

Robert E. Monroe

Vice President, Data Research

Aircraft Owners and Pilots Association

Barney Parrella

Manager, Airport Planning and Development

Air Transport Association

Gilbert F. Quinby

Consultant

John Slowik

Vice President

Airline and Aerospace Department

Citibank N.A.

Summary

In its most recent (2/16/82) forecasts of aviation activity for the period 1982-93, the Federal Aviation Administration (FAA) projected substantial rates of

growth in commercial and general aviation (GA) traffic, as well as a large increase in the size of the GA

fleet. These projections undergird FAA’s National Airspace System (NAS) Plan for modernizing the Nation’s

air traffic control (ATC) system and the timetable the

agency would follow in making the NAS Plan a reality.

The Working Group spent much of the day discussing the adequacy of FAA’s aviation forecasts. These

discussions centered on: 1) the internal structure of

FAA’s econometric model, 2) its reliance on the Office

of Management and Budget (OMB) forecasts of the

gross national product (GNP) and other economic indicators, 3) its high level of aggregation, and 4) its

omission of cyclical economic behavior. The consensus appeared to be that FAA’s forecasting methods

may tend to produce unduly optimistic projections of

economic growth and its effects on aviation.

The group also looked into a number of related factors that could limit substantially the growth envisioned in the Plan. These included: 1) airport congestion; 2) user fees; and 3) financing of aircraft purchases.

The group generally agreed that modernization

would be desirable for reasons of reliability and productivity alone. Their questions dealt not with the need

for the proposed improvements, but with their timing. Slower growth would allow more time, and several participants noted that the choice of technology

might also be affected by the timing of the NAS Plan.

A few extra years could be important, since the system

one could develop now might be significantly different

from one designed later in the decade.

Discussion

On February 12, 1982, the FAA Office of Aviation

Policy and Plans issued “FAA Forecasts on Aviation

Activity, Fiscal Years 1982-1993.” On the title page,

FAA explicitly noted that its projections were “based

on OMB’S January 12, 1982, forecasts of economic variables. ”

Members of Working Group 1 were given a copy

of that document at the outset of the meeting and referred to it often during the discussion of FAA’s

econometric model and the agency’s use of the administration’s economic projections.

The ideas expressed by the group during the meeting

on February 25 fell into two major categories:

1) economic forecasts and 2) related factors of an

economic and noneconomic nature that could affect

FAA’s forecasts for growth in aviation.

41
42 . Review of the FAA 1982 National Airspace System Plan

Economic Forecasts

The FAA Forecasting Model

David Lewis, an econometrician, with the Congressional Budget Office (CBO) led the discussion with an

examination of FAA forecasts of aviation activity over

the last 23 years. In comparing those projections with

actual levels of activity, Lewis discerned three distinct

chronological periods.

During 1959-65, FAA’s 5-year projections for various measures of aviation activity and ATC workloads

proved too low by an average of 18.7 percent. But the

reverse of that pattern occurred during 1966-73. The

agency’s 5-year projections for that period were too

high by an average of 32.5 percent.

In 1974 FAA shifted from trend extrapolation to an

econometric model. While Lewis called this a step forward, he also suggested that the model might prove

only marginally more accurate than past projections.

According to his calculations, the average forecast

error since 1974 has been high by 21.2 percent; the

maximum error for any one year’s forecasts was 34.7

percent too high. (Lewis’ tables are attachment A-l.)

Lewis noted that “there’s been an improvement in

the projection of passenger demand on the air carrier

side. ” But even though some of the 1976 projections

for 1981 were not far off, the Professional Air Traffic

Controllers Organization (PATCO) strike led air carriers “to ground small planes, resulting in improved

load factors, ” he said. So, while FAA’s forecasts for

enplanements proved 4.3 percent too high, its estimate

for domestic revenue passenger miles (RPMs) was 9.o

percent too low. The forecast for total tower operations, however, proved 34.7 percent too high.

Lewis raised this point not to criticize the FAA–

which could not have anticipated the strike, he said—

but to highlight “the importance of each factor in the

forecasting chain, ”

FAA uses four variables in a linear formula to predict RPMs. Lewis argued that two of those variables,

disposable personal income and consumer expenditure

in transportation, “are highly related to each other. ”

If that is so, he asked, “why are they both in here?”

With deregulation in 1978, the airlines went into

what Barney Parrella, Air Transport Association,

called a “shakedown period.” Dr. Robert Simpson, of

the Massachusetts Institute of Technology Flight

Transportation Laboratory, pointed out that “200 or

300 years of transportation economics history tells us

that the pricing activity is chaotic in an unregulated

state. It always goes that way because in transportation you always have spare seats, spare capacity. ”

Yet, the econometric model FAA is using to project

air carrier traffic into the 1990’s does not take into account the fare wars and other competitive behavior

that followed deregulation.

The model also does not incorporate possible

changes in labor costs, Because of agreements signed

before deregulation, the older airlines are locked into

high wage and salary scales. “You can suspect a problem, ” said John Slowik of Citibank N. A., “when one

major airline estimates it only needs 58 percent of

employee-hours it now pays for. Or when the Civil

Aeronautics Board’s own data point out that certain

majors’ fully allocated costs are as much as 89 percent

above a low-cost national carrier. ”

The driving factor in FAA estimates of the workload

imposed by general aviation is the size of the GA fleet.

This is a critically important calculation because rapid

growth in the GA fleet accounts for the greatest proportion of projected needs in FAA’s NAS Plan. Yet,

the agency ignores fuel prices in calculating changes

in fleet size. Lewis suggested, and Robert Monroe of

the Aircraft Owners and Pilots Association confirmed,

that fuel prices are an important factor in the size of

the active GA fleet and in the total number of hours

flown.

Monroe estimates, however, that 15 percent of the

GA fleet is inactive, meaning that those planes have

not flown during the past year. If FAA greatly overestimates the utilization as well as the size of the GA

fleet, it would affect both the agency’s projected workload and the Government’s ability to finance the NAS

Plan through user fees. Specifically, Federal revenue

collections from higher taxes on aviation fuels could

fall far short of current projections. That, in turn,

could shift a greater portion of the burden of financing the NAS Plan from system users to the general

fund.

Economic Variables

GNP and disposable personal income, two highly

related economic factors, are the principal variables

underlying FAA’s calculations of air carrier and GA

operations. FAA does not calculate these factors independently; they are derived from forecasts of economic variables prepared by the Executive Office of

the President, OMB, as of January 1982. Monroe

labeled these projections “a political forecast.”

Several members observed that the administration’s

numbers could be called “targets” rather than forecasts.

Slowik characterized them as “hockey-stick forecasts.

They are kind of flat for a while, and they start going
App. A—Growth Scenarios in FAA’s National Airspace System Plan ● 4 3

up ... because things are always getting better in the

future.;’

The air carrier projections led Samuel C. Colwell,

of Fairchild Industries, Inc., to ask: “What forces are

going to cause (air) traffic growth . . . to go faster than

it did in the ‘70s? Every force that I see, everything

that I look at, says it has to grow slower . . . Fuel

prices, even if they moderate . . . are still at least going to go up as fast as inflation and probably faster . . .

There are productivity increases coming, but they’re

minor compared to the productivity increases we had”

in the last two decades.

Another example of this phenomenon may be seen

in Government projections for general aviation. FAA

estimates that the GA share of instrument operations

at airports will rise from 48 percent in 1982 to 55 percent in 1993. The urgency of the NAS Plan timetable

is based largely on this expected boom in GA traffic.

The FAA forecasts that the size of the GA fleet will

rise from 211,000 in 1981 to 332,900 by 1993. Yet, in

1980, according to FAA, the fleet grew by only 700

aircraft. Last year, it was estimated to have grown by

3,000 planes. Growth is projected to remain slow in

1982-83 but should then explode in the out years. Between 1985 and 1993, FAA expects the GA fleet to expand by over 12,000 aircraft per year.

Because the timing in the NAS Plan seems to hinge

on the growth of the GA activity, the accuracy of its

forecasts for that sector is critically important. Zalman

Shaven of OTA suggested that “we need greater disaggregation” in the data FAA uses to forecast GA activity and other operations. After considering the data,

assumptions, and projections that went into the agency’s GA forecasts, other members of the group seemed

somewhat skeptical of the results.

In projecting the size of the GA fleet, for instance,

FAA assumes “an elasticity of 17, each l-percent increase in GNP leading to a 17-percent increase in the

change of the size of the fleet, ” Lewis pointed out.

“They (FAA) take the aggregate forecasts and just

make a guess at the share of the aggregate that will

be held by” each type or category of GA aircraft, he

said. “There is no attempt to forecast sets, those individual classes, from the bottom up.”

Although GNP drives the agency’s projections for

GA activity, said Lewis, the model assumes that

“there’s a saturation level . . . that means at the

margin, progressively higher levels of income lead to

progressively smaller changes in the demand for aircraft .“

Monroe questioned whether GNP should even be

considered “a causal variable. It’s always been my

understanding that GNP was a consequence of doing

something, not a cause of doing something . . . . If the

airplane is indeed a business tool, then GNP is a consequence of buying and operating aircraft, not a causal

factor.”

Questions were also raised about the accuracy of

FAA data on the present GA fleet. Consultant Gilbert

F. Quinby found that Government recordkeepers

“were very careless about purging accident aircraft out

of the file.” Monroe agreed, pointing out that “the difference between a sheet of paper and an airplane is

where we get into trouble. ” He also noted that the

Government does not have “a good system of purging” to account for aircraft that were exported.

After comparing past GA growth rates with current

FAA projections, Monroe suggested that “the projection of numbers in the Plan is not out of the realm of

possibility.” That, however, seemed to be the extent

of his optimism.

Indeed, he argued that the importance of GNP and

disposable income may be overstated in FAA calculations. Alluding to the Vahovich study, ’ he noted that

“convenience seems to be the primary problem with

most aircraft owners. It’s not the cost. That actually

came fairly well down in the line of concerns, about

fourth or fifth or sixth.”

But in the final analysis FAA seems to have pegged

its aviation forecasts to the administration’s optimism

about economic growth. “All these equations are

driven by highly aggregate variables: GNP, consumer

expenditure (on transportation and) disposable income, ” said Lewis. “They’re very sensitive to those

variables and changes in long-term growth rates. To

the extent that those growth rates are too optimistic,

the forecasts will be too optimistic as well. ”

Cyclical Economic Factors

Although the U.S. economy has made impressive

gains at times, it seldom moves in a straight line. In

recent years, it has gone through several periods of

recession and recovery. Yet, FAA’s forecasts through

1993 apparently ignore the possibility of cyclical fluctuations in the future. The agency assumes a steady

upward march in GNP.

Some members of the group were skeptical of the

forecasts for this reason. “Any trend-extrapolation

model that is just used arbitrarily is going to generate

results like this, and they’re always going to be bad, ”

said Colwell. “And I think they’re making the same

mistake now because we’re in another basic structural

1S. G. Vahovich, General Aviation: Hours Flown and Avionics Purchase

Decisions, FAA-AVP-78-9 (Washington, D. C.: US. Department of Transportation, Federal Aviation Administration, Office of Aviation Policy, May

1978).
44 . Review of the FAA 1982 National Airspace System Plan

change in the industry. And so, if FAA or whoever

is using these models would then apply some logic and

reasons and adjust the models appropriately—not just

rely on the outcome—they would do much, much

better.”

The General Aviation Manufacturers Association

(GAMA) has an understandable interest in estimating

growth in the GA fleet. Yet when GAMA makes “forecasts of production, sales and deliveries (it) will only

do it for one year in advance, ” said David McGowan

of GAMA. “We have no idea what’s going to happen

2, 3, 5, even 12 years down the road . . . . What they

(FAA) are using, I don’t know.”

Using charts, Herman Gilster, of Boeing Commercial Airplane Co., showed how Boeing’s projections

of domestic RPMs for 1980 fluctuated widely from its

initial estimates in 1968 to its final prediction in 1979.

The actual figure in 1980 proved to be 268 billion

RPMs, but the company’s forecasts ranged from about

475 billion (1969) down to 250 billion (1975-76). (See

attachment A-2. )

These fluctuations, said Gilster, suggest that when

“growth is high, or things look well, you forecast high.

And then if you get into a depression area, such as

’74 and ‘75, you lower your forecast dramatically.

(So,) I think there’s a tendency to have your long-range

forecast highly influenced by the short-term economic

situation. ”

Cyclical changes have also lead Boeing to revise its

forecast for 1985 from 700 billion RPMs (1971) down

to 310 billion RMPs (1982). In comparing Boeing’s projections with those of other firms in the industry,

Gilster noted that “the engine manufacturers . . . have

lower forecasts than the airframe manufacturers.” But

he also pointed out that the Boeing and FAA forecasts

of the size of the U.S. commercial jet fleet in the year

2000 closely match. (See attachment A-2.)

The price of commercial airliners is another cyclical

economic factor omitted from FAA’s forecasting

model.

U.S. air carriers, said Slowik, are suffering from a

“serious over-capacity which has been fueled by backto-back negative traffic-growth years. ” Without good

profits, many airlines cannot afford to modernize their

fleet. Yet, he remarked, “there is little doubt that those

airlines who want to operate profitably must replace

old, inefficient aircraft with new-generation equipment .“

To get new aircraft, most companies will need to

sell a portion of their current inventory. But the market

for old aircraft is so depressed, said Colwell, that “the

prices of corporate jets are now equivalent to a used

(Boeing) 727. They are up to $6 to $8 million for a

new, large corporate jet. ”

But if the market for airliners does bounce back, air

carriers might find their benefits short-lived. “The

doomsday scenario that I have,” said Simpson, “is that

the (new Boeing) 757s and 767s coming off the line”

will have to compete against their 727s and other older

aircraft “when all our Columbia Airs and the rest . . .

start grabbing them and putting them into service

again.” And, he added, “unless you put the axe to some

of those airplanes, they don’t physically disappear.

They are always going to come back.”

If that scenario were to transpire, it could also set

off a new wave of price competition which might further erode the profitability of U.S. air carriers.

Other Factors Affecting Future Growth

Airport Congestion

In chapter II of the NAS Plan, FAA acknowledges

that “it is growth in major metropolitan areas (covered

by the large and medium hub airport and reliever airport statistics) that causes special concern. These areas

contain the largest concentration of aviation industry

consumers, representing 90 percent of the air carrier

enplanements and 40 percent of itinerant aircraft operations . . . Because of their high population density, increasing resistance to the adverse environmental impact of airport growth, and the expensive and

difficult task of land acquisition for the enlargement

of existing facilities or construction of new airports,

expansion in these areas is nearly impossible. ”

This chapter, in Barney Parrella’s view, shows that

FAA realizes that “airport availability or capacity at

airports will be the constraining factor, going out to

the year 2000, in terms of growth in the system. ”

Gilbert Quinby added that “One way to test the

realism of doubling the (GA) fleet is to try to figure

out where they’re going to put them with the present

trends in runways, tiedowns, etc. ”

Yet, FAA’s econometric model is unconstrained. In

the words of H. Clark Stroupe, of Booz-Allen &

Hamilton, the forecast “assumes an open-ended supply of air transportation.” Is it consistent, then, for

FAA to take airport congestion into account as a constraining factor in air-traffic management but to ignore that congestion when forecasting air-traffic

growth?

This question was addressed by several members of

the group. Parrella argued that “when you hit that ceiling, which is places to land, that seems to me to be . . .

the ultimate definer of what your forecast will look

like.” Later, he added: ‘We can project these numbers

in a forecast and talk about growth scenarios . . . (but

the) overriding constraint is capacity at the major air-
App. A—Growth Scenarios in FAA’s National Airspace System Plan ● 4 5

ports , . . I mean, are we talking about a forecast that

is really expected to come about, or are we really talking about some kind of target?”

FAA projects that the number of airports in the NAS

Plan will grow from 3,163 to 4,000 by the turn of the

century. That projection was greeted skeptically by

Monroe, who recalled that “when they first established

a Federal airport aid program back in 1945, the intent

was to develop . . . 6,500 (to) 7,500 airports throughout the Nation . , . Well, the last three or four times

that they have published any plan, the number of airports included in the plan has always declined. ”

Several factors, including high real estate costs, are

working to shrink the number of places where an airplane can land. Monroe cited the Los Angeles Basin

as one area where public use airports are disappearing. He quoted FAA data showing that over 300 airports per year have been closed or abandoned since

1965.

Monroe believes that “convenience” has become

more important than cost in an individual’s decision

to purchase a small plane. But when owners find that

they cannot use major airports and are forced to drive

long distances to use strips which provide considerably

less service, they often give up flying. The result, according to Monroe, “is a terrific turnover . . . . Half

the (GA) fleet turns over in terms of numbers of registrations. ” Lack of convenient airports could also constrain the growth of the GA fleet and GA operations.

“Growth is going to be very slow,” Monroe said, “until

we solve the airplane-airport problem. ”

Constraints on airport growth appear inevitable.

Citing his recent experience with Boston’s Logan Airport, Simpson argued that “there is no limit on passengers at this airport. There are ways to handle the

parking lot and some of the building problems at any

of these airports. ” The real constraints stem from

restrictions on aircraft noise and insufficient land for

additional runways.

At Logan, said Simpson, “what we are arguing

about is one little, short 3,800-foot runway to handle

commuter airlines and the possibility of talking the

FAA into some parallel approaches on runways that

are only 1,500 feet apart. That is it. There is nothing

you can do with money to help Boston-Logan, and

if you think you are going to go somewhere else in

the Boston area and put another airport down, you

are not going to do that either. ”

User Fees

How will the United States pay for an improved

ATC system? This seems certain to be one of the

thornier questions Congress may have to face.

In the NAS Plan (page I-34), FAA indicates that the

cost of upgrading the ATC system “will be borne by

the user. ”

During the discussion of user fees, Paul Phelps of

OTA pointed out that the latest FAA forecast assumes

that “the Administration’s user-tax schedule will be in

effect on July 1, 1982, and that money will start going

into the (aviation) trust fund. ” These revenues will

come from taxes on passenger tickets and on aviation

fuel. But the projection, he added, “does not reflect . . . the two-cent-a-year escalator on those gas

taxes, which may be another reason why general aviation local operations and . . . tower operations are so

high in the out years.”

Because the price of fuel is a factor in FAA forecasts

of GA activity, the agency’s failure to take this fueltax escalator into account would tend to add an upward bias to its estimates of local GA operations and

the projected workload of its Flight Service Stations,

which are used primarily by GA aircraft. Monroe

agreed that user taxes slowed GA growth in the 1970’s.

Would increased user taxes exercise a similar restraining effect in the 1980’s? And if the Government

does not receive the expected revenues from these

levies, how will it pay for these improvements to the

system? Quinby suggested that the “economic consequences of total fleet and total (operations) much lower

than this (traffic forecast) might call for a review of

the funding forecast. ”

Cost allocation turned out to be equally thorny.

There are, as Quinby noted, “a lot of up-front costs

that this Plan asks for which are very difficult to

allocate. Who should pick up the tab for increasing

the productivity of the technical personnel that it takes

to man the system? . . . Who should pick up the tab

for changing from leased Bell System lines to (an FAAowned) microwave?”

FAA expects general aviation to account for 75 percent of the increased demand on the system. Should

GA user fees be raised in rough proportion to the demand GA will put on the system?

Quinby did not think so. “From a standpoint of cash

flow, assets (and) payroll,” he said, “the air carrier

business is on the order of 10 times as big as the general

aviation business. ”

Parrella took issue with “this ability-to-pay scenario, ” which “in this current difficult air carrier

market is not just . . . a simple thing that one can

assert anymore . . . . You can’t just say . . . it’s the

deep-pocket industry. We’ve heard from the bankers

that that’s just not the case in this environment . . . .

It’s very inequitable to have cross-subsidization from

one industry to the other. ”
46 . Review of the FAA 1982 National Airspace System Plan

Monroe argued that “only five percent, approximately, of general aviation flights make use of the IFR

system. ”

“And yet,” countered Gilster, “we have another statistic, which is that more than 60 percent of the flights

in the system are general aviation. ”

As this exchange indicates, the group reached no

consensus concerning either the impact of user fees on

traffic growth or the appropriate level of user taxes

each sector of aviation should, or could, bear.

Aircraft Financing

The FAA model for changes in the size of the GA

fleet is driven principally by GNP. It is far less sensitive to aircraft prices and interest rates. That formula

was criticized as too mechanistic as well as too highly

aggregated. “Corporate operations are the fastest

growing part of GA right now, ” said Shaven. Yet by

lumping corporate aircraft with the smaller planes,

which are used largely for personal flying, one could

come up with an estimate of GA fleet size that “may

be totally invalid because you’ve ignored the detail,”

he said.

Lacking detailed and disaggregated data, the group

was unable to reach any conclusions about the issue

of financing GA purchases.

For the air carriers, however, there are essentially

“three primary sources of funds, ” said Slowik. They

are: Commercial banks, equity-type securities and the

long-term institutional market (mostly insurance companies). “There is also a long-term market through

pension funds, ” he added, “but they generally have

rules where they will not lend money to companies

with less than a double-A bond rating, which excludes

all the airlines automatically. ”

“The estimates made by several of the major airlines

indicate net profits of $150 million to $200 million per

year (each) will be necessary if their planned and already-ordered new-generation aircraft are to be financed, ” he said. So, many carriers may not be able

to take delivery of airliners currently on order. Gilster

confirmed that some of Boeing’s deliveries are being

renegotiated.

With Wall Street unreceptive to airline equities and

the institutional market charging the airlines interest

rates 1 or 2 percentage points higher than their other

customers, the carriers have nowhere to turn but to

the banks.

“There would be quite a few carriers that wouldn’t

be in business today if it weren’t for the banks making substantial concessions and putting more money

into them, ” said Slowik. At Citibank, he continued,

“we have had to buy out banks, where Midwestern,

regional-type banks have refused to go along with addition terms.”

Many airlines do not actually own their aircraft;

they lease them from Citibank and other financial institutions. This source of financing, Slowik cautioned,

would be jeopardized by proposed changes in the lease

provisions of the Tax Reform Act of 1981. Airlines

may also be able to benefit from offshore capital. Two

years ago, for instance, “the first Eurobond financing

was arranged for a major airline, ” said Slowik.

Though a return to profitability could save many

of the carriers, it would have to be a very robust

recovery to save them all from bankruptcy. A bank

that foreclosed on an airline today would not be able

to get a very good price for the carrier’s aircraft. So,

the banks might decide to wait until the price of used

aircraft climbs substantially before calling in their

notes.

Alternatively, a bank could force the large carriers

to liquidate a portion of their fleet to pay off their

debts. In other words, said SIowik, “it wouldn’t necessarily require them to go bankrupt to get the

money. ”

Questions for

Near the close of the

Working Group 2

meeting, the group touched

on some issues it would like to see Working Group

2 explore:

I. If FAA’s scenario of rapid growth is judged to be

2.

overly optimistic, can the Government prudently delay a decision to upgrade the ATC system?

Quinby characterized the present system as “a

tired bunch of hardware (that is) trying to run

software with band-aids on it. It was designed to

be shut down every night for maintenance, and

it is not being shut down every night . . . When

it breaks, the lack of redundancy and distributedprocessing capability hurts them.”

How integrated are the various components of

FAA’s NAS Plan?

From his reading of the Plan, Monroe concluded that “the elements are so interconnected

and . . . interdependent that you almost have to

make the decision at the beginning to go the

whole 10 yards . . . and, hence, it is not subject

to . . . modification at any major part by any

short-term alternations in forecasts. ”

But Stroupe expressed a “hope that any new

technology would have flexibility to make midcourse corrections towards demand in the 10- and

15-year timeframe.”
App. A—Growth Scenarios in FAA’s National Airspace System Plan . 47

3. Would the choice of technology be likely to

change if more time were available before the improvements would be needed?

“Well, quite frankly, ” said Stroupe, “a 2- or

3-year error in some of the saturation points is

a significant difference in what type of technology

and what type of system you might consider feasible to implement . . . You may open up alternatives if the number to saturation is 8 years instead of 4.”

4. Specifically, which of the options rejected by

FAA might prove to be superior alternatives if

growth were slower than expected and more time

were available before capacity improvements had

to be in place? (See Response to Congressional

Recommendations Regarding FAA's En Route

ATC Computer System, DOT/FAA/AAP-82-3,

January 1982.)

Questions for Staff Investigation

The Working Group also raised several issues that

might be addressed by OTA staff, possibly in cooperation with the General Accounting Office (GAO) or

CBO:

1. To what extent are the scope and timing of FAA's

plans driven by the need to accommodate growing demand, as opposed to the need to replace

obsolescent equipment or to increase productivity?

2. How reasonable and consistent are FAA’s aviation forecasts, with regard to procedures and economic assumptions as well as specific projections,

and do they provide a satisfactory basis for FAA's

long-range plans ?

3. Specifically, how does FAA arrive at its forecasts

of workloads and capacity constraints at individual en route centers, which seem so vital to

the timing of its NAS Plan?

4. How accurately do FAA’s forecasts reflect the

potential impact of aviation user fees, and what

effect will lower rates of traffic growth have on

the revenues with which to pay for the proposed

improvements ?
48 . Review of the FAA 1982 National Airspace System Plan

Table A-l-l .—Five-Year Aviation Activity Forecasts Compared

With Outturn (percent difference)

Commercial Revenue Hours flown All

Forecast For the air carriers passenger in general itinerant Total

made in year enplanements miles aviation operations operations

1959

1960

1961

1962

1963

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1964

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

– 1.3

– 9.5

–27.5

–32.1

–41.3

–31 .4

–14.1

9.4

23.6

23.9

21.1

26.3

19.0

22.3

14.0

–10.1

1.6

4.3

– 6.5

– 9.7

–26.0

–31.4

–41.3

–33.6

– 19.8

0.5

13.0

15.9

21.2

33.0

28.6

33.7

18.3

– 7.2

–14.7

– 9.0

– 0.6

– 1 . 2

– 15.3

–23.6

N/A

–23.5

– 16.3

– 1.6

9.1

7.4

4.6

– 0.6

– 0.6

– 6.8

– 10.4

– 9.5

– 1.2

15.7

6.0

– 12.7

–20.0

–20.6

–26.9

–24.0

– 8.0

32.4

43.8

49.7

37.7

19.7

14.1

1.2

2.3

6.4

11.3

25.7

9.7

–21 .6

–28.9

–27.3

–32.5

–24.9

– 5.2

42.2

54.9

58.4

42.4

25.9

22.9

4.5

8.8

12.8

16.0

34.7

SOURCE: David Lewis, Congressional Budget Office, from FAA Aviation Forecasts, 1959 to 1976.

Tabie A-1.2.—Summary of Forecast Periods

Performance

Period Method 5 years aheada Environment

1959-65 Trend forecasting: Average error – 18.7°/0 Expanding, prosperous economy.

unspecified links to economy, Worst year –32.5°/0 Rapidly growing population.

business cycle, population, Declining first-class and coach

fares, competition from other fares, (declining unit costs

modes. because of increasing use

of jets).

1966-73 Trend forecasting: Average error +32.5°/0 Softening trends in aviation

unspecified links to economy, Worst year +58.4°/0 activity. Increasing ticket taxes,

business cycle, population, rising fares. Forecasts made in

fares, competition from other 1969 (published January 1970)

modes. assumed 4.25 percent growth

rate in fiscal 1973, to continue at

that rate through decade. inflation 2 percent per year from

fiscal year 1973. Fares projected

to decline in real terms (flat in

current dollars).

1974-onwards Linear econometric models. Average error +21 .2°/0

Worst year +34.70/0

aOperations forecasts.

SOURCE: David Lewis, Congressional Budget Office.
.

App. A—Growth Scenarios in FAA National Airspace System Plan . 49

Table A-1-3.—FAA Forecasting Models

Causal Elasticity

Measure Model form variables (at mean)

Air carrier operations

Revenue passenger miles (RPMs) Linear econometric Revenue per passenger mile . . . – 0.64

Consumer expenditure in

transportation . . . . . . . . . . . . . . 0.15

Disposable income. . . . . . . . . . . . 1.80

Investment in transportation . . . 0.26

Total domestic operations RPM X 2

General aviation

Tower workload:

Change in fleet size

Itinerant operations

Local operations

Instrument operations

Flight service station workload:

Aircraft contacted

Pilot briefs

VFR flight plans

IFR flight plans

Average Average

Load seating stage

factor x capacity x length

Linear semilog

N/A N/A

GNP . . . . . . . . . . . . . . . . . . . . . . . . 17,00

Aircraft price . . . . . . . . . . . . . . . . . – 4.00

Interest rates . . . . . . . . . . . . . . . . . – 2.00

Sales . . . . . . . . . . . . . . . . . . . . . . . . 3.00

Time . . . . . . . . . . . . . . . . . . . . . . . . Negative

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 1.07

Fuel price. . . . . . . . . . . . . . . . . . . . – 0.23

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 0.21

Students. . . . . . . . . . . . . . . . . . . . . 1.00

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 1.50

Linear Itinerant operations . . . . . . . . . . . 1.10

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 1.60

Fuel price. . . . . . . . . . . . . . . . . . . . – 0.30

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 0.60

Fuel price. . . . . . . . . . . . . . . . . . . . – 0.27

Linear Fleet size . . . . . . . . . . . . . . . . . . . . 1.60

Fuel Deice . . . . . . . . . . . . . . . . . . . . – 0.21

N/A - Not applicable.

SOURCE: David Lewis, Congressional Budget Office
50 ● Review of the FAA 1982 National Airspace System Plan

—

Attachment A-2: COMPARISON OF FAA FORECASTS WITH

INDUSTRY FORECASTS (BOEING COMMERCIAL AIRPLANE CO. )
App. A—Growth Scenarios in FAA National Airspace System Plan “ 51

Figure A-2-3.— Comparison of Industry Forecasts of Domestic Air Traffic in 1985 and 1990

BOE = Boeing

GE = General Electr!c

BAe = British Aerospace

FAA = FAA Baseline (1980

L = Lockheed

McD = Douglas

P/w = Pratt &Whitney

HI

900

BOE GE BAe FAA L McD P/W

1980

SOURCE: Boeing Commercial Airplane Co.

B

Hi

BOE GE BAe FAA L McD P/W

1980

Figure A-2.4.— Market Forecast for U.S. Commercial Jet Passenger Fleet, 1980-2000

4,000 ‘

3,500

3,000

2,500

2,000

1,500

1,000

500

0

I Three and four ermine 3.384

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000

Year end

SOURCE’ Boeing Commercial Airplane Co.
. —

Appendix B

COMPUTER AND COMMUNICATION

TECHNOLOGIES IN FAA’S

NATIONAL AIRSPACE SYSTEM PLAN

Members of Working Group 2

(March 9, 1982)

H. Clark Stroupe, Chairman

Vice President, Booz-Allen & Hamilton, Inc.

Michael J. Ball

U.S. Air Force

Paul Baran

President, Cable Data Associates

W. W. Buchanan

Senior Associate, SES

James Burrows

Director, Institute for Computer

Technology

Anthony Csicseri

General Accounting Office

George Litchford

President, Litchford Electronics

Gilbert Quinby

Consultant

Harrison Rowe

Science and

Bell Laboratories, Crawford Hill Laboratory

Robert W. Simpson (Chairman, Working Group 1)

Professor, Flight Transportation Laboratory

Massachusetts Institute of Technology

Willis Ware

The Rand Corp.

Other Participants

John Andelin, OTA

Neal Blake, FAA

M. Karen Gamble, OTA

Sam Hale, OTA

Valerio Hunt, FAA

Larry L. Jenney, OTA

William Mills, OTA

Peter J. Ognibene, consultant to OTA

Paul B. Phelps, OTA

Zalman Shaven, OTA

Norman Solat, FAA

David Traynham, Subcommittee on Aviation of the

House Committee on Public Works and Transportation

Summary

In its National Airspace System (NAS) Plan made

public in January, the Federal Aviation Administration (FAA) outlined its proposals for modernizing the

Nation’s air traffic control (ATC) system.

Working Group 2 commended the NAS Plan as a

worthwhile statement of goals and an advance over

previous plans. However, the panel also suggested that

FAA may have underestimated both the technological

risks inherent in individual elements of the Plan and

the scheduling risks involved in implementing and integrating these elements into a highly automated system. In general, the participants felt that there was sufficient uncertainty in FAA’s traffic forecasts to require

greater flexibility in its implementation schedule, particularly for the en route computer replacement.

While the group agreed that improvements are

needed, most members were skeptical of FAA’s plan

to “rehost” the current en route software in a new

mainframe computer. Because that software, too, will

eventually be replaced, some suggested that the interim

rehosting step could be bypassed. By upgrading 9020A

computers to 9020Ds, FAA could increase its computational capacity sufficiently to postpone congestion at

any en route center until the mid-1990’s. This would

give FAA additional time to benefit from improved

software and the distributed architecture of modern

computer hardware.

The group also indicated that the lack of a clear

description of system architecture made it difficult to

judge the details of computer and communications system design. Members also suggested that FAA devote

additional attention to satellite-based systems for communication, navigation, and surveillance, as well as

the impact of greater automation on those who use

the ATC system.

Though the word “National” is in the title, the group

noted that the NAS Plan is structurally incomplete.

It largely excludes military aircraft and ATC facilities,

52
App. B—Computer and Communication Technologies in FAA’s National Airspace System Plan ● 5 3

as well as the majority of the general aviation (GA)

fleet which operates under Visual Flight Rules (VFR).

Some participants also questioned whether the sharp

distinction between “controlled” and “uncontrolled”

airspace can be maintained in the future.

The Plan

Working Group 2 agreed that the Nation’s ATC system needs to be modernized, despite their questions

on technology and timing. In an observation that

reflected the group’s thinking, Chairman H. Clark

Stroupe, vice president of Booz-Allen & Hamilton,

Inc., said, “No one . . . has seriously entertained the

concept of doing nothing. ” The group also had general

praise for FAA’s 1982 NAS Plan, which the agency

made public in January. Consultant Gilbert F. Quinby

felt it was “to be commended at a policy level, ” and

Stroupe called it “a fairly significant set of goals, even

bold in some sense, compared to some of the previous

plans FAA has had. ” Other participants echoed these

overall evaluations.

The choice of technologies was generally considered

to be well within the state-of-the-art, although there

was disagreement about specific components. George

Litchford, president of Litchford Electronics, commented that, “As far as using the new technology

(goes), I think it’s being used in a conservative sense.

In aviation you can’t plunge ahead with brand new

technology. You usually have to use quite well-proven

technology, and I think in that sense it’s a fairly conservative plan. ”

Others felt the Plan might be too conservative. “I

looked at the technology, ” said Paul Baran, President

of Cable Data Associates, “and it looked very, very

old . . . . There seems to be a slight mismatch there

between what we’re able to do and what we’re proposing to do.” W. W. Buchanan, senior associate with

SES, agreed. “Certainly the technology doesn’t show

an awful lot of advancement over the plans of 5 years

ago or even 10 years ago, ” he said.

Several participants expressed apprehension, however, particularly when the discussion shifted from the

individual technologies to the way they would be integrated and implemented by FAA. Dr. Willis Ware

of The Rand Corp. put these concerns most strongly,

saying “It’s dripping with technical risk all over. About

every third project talks casually about software. I

would judge that most of those software remarks are

not well-founded in terms of the resources needed to

accomplish them. The en-route-control computer replacement I would regard as especially risky, primarily

because of the software as it now exists in FAA. And

they have a terrifying problem of how to get anywhere

from where they are now.” (See below under “Rehosting” and “Software and Sector Suites.”)

In addition to its technological risks, the NAS Plan

was also criticized for its omission of important

elements of the aviation community, notably the

armed services. “The military seems to be much more

aware that they’re part of the National Airspace System than FAA does in this planning document, ” said

Stroupe. Litchford agreed, adding, “To FAA, it’s like

the military doesn’t exist, and I think that’s one of our

major problems in all this documentation. ”

“The National Airspace System is defined in the

FAA plan as an FAA system only,” said Mike Ball of

the Air Force, who represented the Department of Defense (DOD). It “doesn’t address an architecture for

the entire system because it leaves out the militaryagency facilities. But beyond that, it’s definitely not

an airspace system plan because it doesn’t address the

overall needs of other people who are currently operating outside the IFR (Instrument Flight Rules) system. ”

This includes most of the general aviation fleet, which

FAA puts at 214,000 aircraft, whose operations are

largely under VFR. (See below under “General Aviation.”)

The group was also concerned about the haste with

which FAA proposes to implement the NAS Plan. It

was the consensus of Working Group 1 that FAA’s

traffic forecasts, based on last year’s economic projections from the Office of Management and Budget

(OMB), were unduly optimistic. Working Group 2

seemed equally skeptical of agency projections of an

overloaded en route ATC system in the mid-1980’s.

In addition, there were questions about the timing

of the implementation schedule itself. The high level

of automation in the NAS Plan involves “a whole new

series of problems, ” according to Dr. James Burrows,

director of the Institute for Computer Science and

Technology. If one component falls behind schedule,

it would send “ripples into everything else” in a way

that “is not clear from looking at this book. ” Ware

shared this view: “If anything slips, the whole thing

slips. ”

Dr. Robert W. Simpson, professor, Flight Transportation Labs, MIT., who chaired Working Group 1, observed that, “One thing I’m sure of is that the forecasts

are uncertain, and if I were planning a system this large

I’d be planning it in such a way that I could accommodate it one way or the other. ” Ware agreed: “It

(looks) like a logical sequence if you have no problems . . . (but) there’s no plan for what happens if you

have real problems.”
54 ● Review of the FAA 1982 National Airspace System Plan

Technologies

Rehosting

The group devoted a considerable amount of attention to FAA’s decision to “rehost” the existing en route

computer software in a larger mainframe computer,

and only then replacing the trouble-plagued software

itself. In an observation shared by many members of

the group, Stroupe said, “I couldn’t find the compelling reasons for a short-term rehosting approach to the

computer (replacement) that seem to outweigh a lot

of compelling reasons for a better long-term solution

with more modern technology. ”

FAA spokesman Neal Blake explained that agency

forecasts of air traffic growth were crucial in Administrator J. Lynn Helms’s decision to rehost the ATC

software in a new computer. “We clearly needed to

get on with increasing the capacity of the air traffic

control system in this decade, now in the late 1980’s

or early 1990’s or beyond . . . . He (Helms) felt that

we could not take on a program which had both hardware and software risks and be able to provide any

near-term improvements in, say, the mid-1980’s timeperiod.”

Ware, who felt that the two-step computer replacement was “especially risky, ” reacted to Blake’s argument by asserting that “the portability of software is

mythology” and adding that “the system-design contractor (for phase two) will be constrained, for better

or for worse, by the choice of the rehosting instrument

or by whatever reasonable enhancement can be made

in the host by upgrading within a family of computers. ”

Several members of the group then suggested that

FAA might be able to skip the rehosting step entirely

if it were willing to upgrade its present 9020 computers

where necessary. FAA forecasts “operational delay

days”* during the 1980’s at only four en route centers,

all of which use the 9020A computer. The 9020D, already installed at 10 centers, has 2.5 times the computational capacity of the A-model. FAA documents

suggest that upgrading 9020A computers to D models

would alleviate congestion at ATC centers until the

mid-1900’s. FAA has already successfully upgraded

from 9020A to D in its Jacksonville center, and the

complete engineering and data package resulting from

this experience considerably reduces the technical risk

of doing so at other centers.

In the shorter term, FAA might also be able to relieve en route congestion by redrawing the boundaries

● Defined by FAA as a day when utilization of the 9020’s processing capacity

exceeds 80 percent of its available capacity for 1 hour or more.

of certain ATC sectors. Zalman Shaven of OTA

pointed out that the centers where congestion has been

projected “are adjacent to areas covered by centers that

have excess capacity. ” Ball suggested that “maybe the

solution to this capacity problem is to bulge out your

center boundaries” to alleviate congestion.

When asked if the agency had considered upgrading

the affected A-models to D-models, Blake replied: “We

looked at it, obviously . . . . I think the Administrator

felt it was better to get a new system . . . we could

build on . . . until we could get what we like . . . .

The earlier we can get the new system in, the earlier

we can start consolidating—saving people and saving

money. ”

Buchanan agreed with Blake. “I am, perhaps, a little bit more uncomfortable with keeping the 9020s any

longer than is absolutely necessary . . . . I would think

it would be very important that FAA get some new,

modern computer power at the earliest possible time. ”

This appeared to be a minority view, however.

Baran’s observation seemed closer to the group’s general perception. “I wonder, ” he said, “whether it may

pay for us just to start now working on the high-level

(programing) language and go parallel with development of the computers, so when the time comes, we

won’t find ourselves implementing computer systems

that are 5 or 10 years old to start with . . . . You either

swallow a big pill now, or you’re going to have to

swallow a lot of pills the rest of the way. ”

Several members of the working group also expressed concern about FAA’s strategy of awarding

both contracts (new host and new software) at the

same time. They raised the possibility that only one

contractor, IBM, might be in a position to win them.

Burrows characterized the situation as “a procurement morass. It seems to me that when you start talking about replacing a 9020 and converting the current

software, that is IBM . . . . Once you have emplaced

IBM equipment as the follow-on equipment and talk

about modifying that equipment to be compatible with

the new software, . . . that is IBM again. So what they

have . . . (is) a two-phase procurement which has

guaranteed IBM in both of them. ”

Litchford agreed: “It is going to be hard for them

to really solicit open, system bids before they select

the whole. ” Anthony Csicseri of the General Accounting Office (GAO) added, however, that GAO had

already informed FAA that the plan was subject to

GSA procurement regulations requiring competitive

acquisition, and that compliance “(would) not slow

down the acquisition process needed to bring in a

rehost system, if that’s what’s really required. ”

In the end, however, the issue of rehosting remained

unresolved. “It looks to me, ” speculated Ware, “that

what the Administrator has announced as a strategy
App. B—Computer and Communication Technologies in FAA National Airspace System Plan “ 55

is to get the money flowing, because he can’t count

on what the congressional attitude will be in 10

years . . . . Given the vagaries of how Government

works and congressional funding, just the prudence

of delaying a decision that might otherwise be sensible becomes questionable. So, therefore, it is really a

judgment call. ”

Stroupe agreed. “It is a political and not a technical

issue .“

Software and Sector Suites

In his written presentation, FAA’s Valerio Hunt indicated that “two major parallel efforts will be initiated . . . this summer. One of these efforts will be

the procurement of a host computer that will possess

the capability of executing the existing 9020 software.

This strategy will provide the earliest increase in computer capability that can also be used as an integrated

part of the total system replacement . . . . The second

parallel effort initially focuses on a total integrated

system design for the entire system. This is followed

by development of the new sector suite (of display terminals for controllers), a suitable data network, and

the new software system.”

Although Hunt as well as Blake characterized these

programs as “parallel,” they are not independent of

each other because FAA expects its host computer will

subsequently run the new system software. As a consequence, the hardware decision could have a considerable impact on software design and the functions

assigned to the sector suites.

“The consolidation and integration of the terminals

with the en route system seems very bold, ” said

Stroupe, yet in examining the NAS Plan he found that

“the whole partitioning and architecture of the system

is not clear in many of the alternatives. ” Later, he

asked: “has their proposal precluded going to any appropriate architecture for a very advanced, very automated system in the ‘90s?”

Ware replied that “your question is unanswerable

because, in this document, there is no evidence of a

system architecture . . . . It’s the classical jurisdictional

partition. The en-route centers are doing their upgrading. The communications guys are doing their upgrading. The Jacksonville center is doing its thing. There

is no system architecture described in there. ”

When members of the group sought more details on

the architecture of the new ATC system, Blake indicated that the agency has placed most of the burden

of system integration on the contractors who will provide FAA with the elements of its new ATC system.

“The vendor will deliver us an operating system which

includes the hardware with whatever modifications he

feels are proper ones for his machine . . . So he is

delivering us, really, a turnkey system . . . . We will

assume that in this decade we cannot build a perfect

hardware-software package and that we will have to

operate at the sector-processor level during certain

types of failure . . . . The system contractor delivers

a set of sector suites suitable for terminal and en route

operations and tower operations. He delivers a new

software package which includes all of the functions

that were resident in the 9020s plus direct-route capability, which are the first steps of the AERA (Automated En Route Air Traffic Control) program. ”

Ware characterized this development and procurement strategy as “kind of a neat gambit, ” one that

“pushes a lot of risk off FAA and onto those vendors.”

Communications

In his presentation to the group, FAA’s Norman

Solat outlined the agency’s planned changes in the

ATC communications systems. Several participants

had indicated that this aspect of FAA’s proposal was

difficult to assess because of the lack of detail in the

NAS Plan.

They also questioned Solat’s conclusion that the

agency’s investment in the existing communication

system precludes major change or the substitution of

a radically different technology. Solat pointed out:

“What we have got at the facilities are the rights of

way and the equipment and the microwave links. They

are already there and paid for and owned by the taxpayers.”

Ware took issue with Solat on this point. “I would

argue that communications technology is not an issue, ”

he said. “Just go out and buy it . . . . How do people

in the present world shove data around mixed with

message traffic? Packet nets. Look at the world. That’s

the way it’s going, and FAA’s dedicated line (approach)

is kaput. ”

Harrison Rowe of Bell Laboratories wondered about

characteristics of the data transmissions that determined FAA’s design of the communications portion

of the NAS Plan. “The basic things that drive what

goes on in communications are not spelled out here

in enough detail to let you get an informed opinion

about whether it makes sense or not, ” he said. “We

haven’t heard any of the technical details about this

Mode-S (transponder) and the (air-ground) data link

and how it is all going to work. ”

Rowe pointed out that the frequency of transponder

interrogations can be of critical importance. If they

occur infrequently, the Mode S system would be adequate. “But if all these people flying around are interrogating each other all the time, there may be a lot
—

56 . Review of the FAA 1982 National Airspace System p/an

of traffic going on up there. You wonder if that system

is going to overload or if it’s going to create interference hundreds of miles away. ”

Satellites

In “reading the communications part” of the NAS

Plan, said Baran, “one has the feeling that you’re

reading papers maybe 20 years old. There is no appreciation for the satellite and what it means in communication systems. ” Litchford agreed. “Nowhere in

the Plan, ” he said, “are they really looking at satellites

seriously until after the year 2000.”

Solat argued that it is not clear whether a satellitebased communication system is cost-effective for handling trunk message traffic in the ATC system. FAA

now has 2,000 equivalent voice-grade circuits, and

Solat envisioned that a satellite Earth station could

serve as the distribution center for messages on those

circuits. But, he added, “right now, because of the

capacity and the loads that are on those circuits, we

don’t see that there is a major payoff.”

DOD is also concerned, Ball noted, because FAA

appears to have “summarily dismissed” the NAVSTAR

satellite and the Global Positioning System (GPS) used

by the armed forces. “The problem between the FAA

and DOD is how much of the coding are we going to

release to civil use, ” he said. “In other words, we can

locate (aircraft) extremely accurately, but we don’t

necessarily want to give that capability to everybody

in the world. ” He went on to say that the amount of

coding proposed by DOD for release to civil aviation

more than meets the navigational accuracy requirements for nonmilitary users of the airspace.

FAA, according to Litchford, “argues that you really

can’t get landing accuracies” with GPS. Stroupe took

a different tack. “The fact that you can’t use GPS to

land an aircraft doesn’t say you shouldn’t use it to

replace one-mile-accuracy radar. ”

User Impacts

Some participants felt that, in drafting the NAS

Plan, FAA did not give sufficient attention to the needs

of certain elements of the aviation community. The

Plan focuses almost exclusively on how to achieve a

highly automated form of control for IFR traffic,

especially during the en route portion of flight. There

does not appear to be adequate concern for VFR traffic or operations at low altitudes (under 6,000 ft).

Moreover, the plan is written almost wholly from

the perspective of the ground-based air traffic controller. Litchford labelled the plan as “a controller’s

wish book. In other words, it is aimed at the controller

himself; it doesn’t talk about the user’s needs.”

Department of Defense

The military services account for about 20 percent

of all domestic traffic and as much as 46 percent of

operations at en route centers like Albuquerque. In addition, they must also protect the Nation from airborne

intrusions and attacks. Nevertheless, DOD “was not

consulted by FAA prior to the announcement of the

plan, ” according to Ball. The NAS Plan, in his view,

“essentially has been designed as an improvement to

a point-to-point air transportation system. But the majority of DOD use of the national airspace is not pointto-point air transportation but, rather, training missions . . . and they are basically left out of the systern. ”

That omission also seems to be reflected in the air

traffic growth projections on which the NAS Plan was

based, FAA’s “definition of the system demand is misleading, ” according to Ball. FAA’s “traffic count,

which gives the military traffic as 4 percent, is based

on (operations at) FAA towers only. But if we take

a look at all the traffic that is controlled in the IFR

air traffic control system in the CONUS (Continental

United States), DOD accounts for about 20 percent

of the traffic count. ” Much of this traffic (and a good

bit of civilian traffic as well) is handled by DOD’s 233

ATC facilities and nearly 8,000 controllers in CONUS.

DOD has cooperated with FAA to ease the effects

of the controllers’ strike by transferring “a good deal

of our flight operations from demand on the FAA system or the FAA portions of the system to our own facilities, ” according to Ball. Moreover, DOD has “a

large program under way to relocate most of the training areas . . . to get away from the (areas of) heavy

civil air traffic and try to help out. ”

DOD is concerned that FAA’s requirement for

Mode-S transponders may cause an increase in military

expenditures with no appreciable increase in benefits.

“Cost estimates to equip DOD aircraft with Mode-S

are in excess of a billion dollars, ” said Ball, “and we’re

not sure Congress wants us to spend that kind of

money for something that doesn’t enhance our warfighting capability.”

While Mode S avionics may have no appreciable effect on the aerodynamic performance of commercial

or GA aircraft, they could have an adverse impact on

military aircraft. “There is great concern (at DOD)

about sticking more black boxes and more displays

and more antennas on high-performance fighter aircraft, ” said Ball. “From what we’ve heard about the
App. B—Computer and Communication Technologies in FAA’s National Airspace System Plan . 57

antennas that will be required for TCAS (Traffic Alert

and Collision Avoidance System), we’re going to lose

operational capability on fighters and other highperformance aircraft. ”

On the broader question of airspace surveillance,

FAA indicates that, in the future, it will rely less on

primary radar to monitor air traffic. “We see an evolution toward a system that is more directly based on

Mode-S, ” Blake told the group. “The plan says that

by the year 2000 we hope to have pretty well dropped

our dependence on primary radar for en route services.

That is, the current ATC type or the joint type radar.

And we wiIl be using primary radar , . . primarily for

weather detection. ”

FAA believes the ATC system will be able to maintain better surveillance over air traffic through secondary radar and Mode-S transponders. But what about

aircraft not equipped with these beacons? Ball expressed concern about the implications of this basic

change in the surveillance system. “The elimination of

the surveillance capabilities by the year 2000 is acceptable if we feel that (there is) another means . . . of

maintaining the air defense and air sovereignty missions of the Department of Defense. ”

Military training missions will also be affected by

the shift to secondary radar. “Half of our low-level

training routes right now are flown under Visual Flight

Rules because we don’t have adequate communications

or surveillance from the FAA to operate under Instrument Flight Rules, ” said Ball. “There is concern about

the validity of VFR when we have got an F-4 down

at 300 feet, going at 500 knots. It is a bit difficult for

him to see and avoid (other aircraft) or for the Piper

to see and avoid him. ”

Ball carried this criticism one step further. “The

military expends a lot of money and effort in providing

to the FAA system information on the scheduling and

actual use times of those routes, . . . but the whole

thing is totally inefficient right now. The schedules are

buried in a pile of messages that are still on a clipboard

somewhere. There is no graphic display. The Flight

Service Station guy is overworked, giving weather

briefings and everything else. He is not required to give

a mandatory briefing of military activities to the

general aviation VFR pilot—only on request. ”

General Aviation

Even though the NAS Plan affirms freedom of access to the airspace as a basic right, FAA envisions a

highly automated ATC system oriented toward operation of well-equipped aircraft flown by experienced

pilots. Some segments of the GA fleet, notably turbinepowered business aircraft, are of this type and regularly use the ATC system, but most GA aircraft do not.

Yet the NAS Plan devotes little attention to the 90 percent of GA operations that take place under VFR. The

NAS Plan apparently assumes that the present distinction between “controlled” and “uncontrolled” airspace

will continue far into the future, but if FAA projections of a greatly expanded GA fleet come to pass, the

extent of positive control may have to be broadened

considerably into uncontrolled areas where most VFR

flights now occur.

Some participants did not think the difference between IFR and VFR, or between controlled and uncontrolled airspace, could be perpetuated indefinitely. One of them was Ware, who asked: “Does this plan

provide a system which is a proper foundation for

gracefully extending (air traffic control) . . . down to

sea level?”

“That’s an important issue, ” said Baran, on which

FAA “punted . . . implying that we’re going to have

VFR forever . . . , I think a plan that covers the period

through the end of the century should include the implications of that potential change. ” In the future,

perhaps near the turn of the century, said Ball, “the

Visual Flight Rules concept just will not work, and

we’ll have too many ‘midairs, ’ and the American public

will demand a total airspace system. ”

The direction charted by FAA for the ATC system

will necessarily increase the cost of entry with the requirement for Mode-S transponders and other avionic

equipment. “If one expects people to voluntarily equip

with something, there has to be a benefit; there have

to be services, ” said Blake. And in the future, he continued, “if you want to get the good ATC services, you

will have to buy it. If you don’t want them, that is

your choice. ”

FAA forecasts indicate that significant growth in the

size of the general aviation fleet will result in much

greater demand on its ATC centers. Quinby took a

mixed view of that projection. “The count of the active general aviation fleet that comes out of this

forecast is substantially higher than what seems realistically attainable, hangarable, maintainable, manufacturable and so forth, ” he said. However, he also

contended that “it’s conceivable . . . that half of the

total general aviation active airplanes will be routinely engaged in the ATC system” in the future. High-performance corporate aircraft, the heaviest GA users of

ATC services, today comprise the fastest growing segment of the fleet.

Automation 

The new ATC system would make more extensive

use of computers and automated modes of operation

to increase the productivity of controllers. FAA claims

that, when hardware and software are operating,
58 . Review of the FAA 1982 National Airspace System Plan

higher productivity will lead to lower manning levels

and significant cost savings,

“I was interested in the claims that are made for personnel savings, ” said Buchanan. “It seems that all of

the actions, principally the automation phases of the

project, claim substantial savings in personnel. One

wonders if FAA has really considered, though, what

kind of staffing enhancements they would have to have

to adequately support (and maintain) . , . a considerably higher level of automation than they are accustomed to handling. ”

Burrows expressed similar concerns. “There are

statements about how we are going to load up the people by adding more automation, ” he said, “and I was

wondering whether we’ve done experiments to show

that was true . . . or whether those were just faith

statements, that somehow between here and there we’ll

figure out how to do that.”

Simpson stressed the importance of “human interaction” with an automated control system, where much

routine decisionmaking is done by computers. “It’s not

going to be just keyboarding and monitoring and

watching the software do the work. (Ideally, it should)

be the controller commanding that software to do

what he wants it to do. ” No decision should be “made

by other than a human being. The machine can present the decisions to him. He’s got to pass it through

his brains and say, yes, that’s what we want, and pass

it back to the machine . . . . Otherwise, the machine

is controlling, and the controller is trying to keep up

with the decisions the machine is making. I don’t think

we’ll ever get to that position. ”

The Rand Corporation Report

The Rand Corp. recently released a report entitled

“Scenarios for Evolution of Air Traffic Control” in

which it takes issue with FAA’s approach to automation in the AERA program. The Rand report was not

discussed specifically by the group, since it was not

available at the time of the meeting. However, the concerns about automation expressed by working group

participants closely paralleled the findings of the Rand

study (see attachment B-l).

Rand’s principal conclusion is that the goal of full

automation sought under AERA is a questionable research and development strategy that may present

serious problems with regard to safety, efficiency, and

increased productivity. An ATC system in which computers make most of the time-critical decisions in controlling aircraft, while the human operator serves in

a managerial and back-up role, implies a needlessly

complete and irrevocable commitment to automation.

Rand argues for an alternative approach, called

“shared control, ” that would construct the future ATC

system as a series of independently operable, serially

deployable modules that would aid—not replace—

the human controller and keep him routinely involved

in the minute-to-minute operation of the system.
App. B—Computer and Communication Technologies in FAA National Airspace System Plan ● 5 9

ATTACHMENT B-l: EXCERPT FROM “SCENARIOS FOR

EVOLUTION OF AIR TRAFFIC CONTROL”1

VI. CONCLUSIONS

We have considered several alternative ATC futures, beginning

with a Baseline case in which nothing beyond the most conservative

R&D projects paid off. We have concluded that the approach of simply

adding more and more controllers is ultimately counterproductive from

a performance standpoint. We have examined the FAA’s plan to use

advanced computer science technology to construct a fully automated

ATC system for application near the year 2000. The expected aircraft

safety levels, fuel-use efficiency, and controller productivity have led us

to question that plan and to suggest that there maybe a middle ground

consisting of a highly, but not totally, automated system.

We believe that pursuing the goal of full-automation AERA—with

little regard for interim systems or evolutionary development-is a

very questionable R&D strategy for ATC. It seems unlikely that a

large-scale multi-level AERA system that can effectively handle nonroutine events, show stable behavior under dynamically changing conditions, and be virtually immune to reliability problems can be implemented in the foreseeable future. Human controllers may be required

to assume control in at least some of these situations, although at

present there is no conclusive evidence that they would be able to do

so; indeed, some evidence and opinions from the human-factors community suggest that they would not be able to.

The AERA scenario presents serious problems for each of the three

major goals of ATC—safety, efllciency, and increased productivity. By

depending on an autonomous, complex, fail-safe system to compensate

for keeping the human controller out of the routine decisionmaking

loop, the AERA scenario jeopardizes the goal of safety. Ironically, the

better AERA works, the more complacent its human managers may

become, the less often they may question its actions, and the more likely

the system is to fail without their knowledge. We have argued that not

only is AERA’s complex, costly, fail-safe system questionable from a

technical perspective, it is also unnecessary in other, more moderate

ATC system designs.

Some AERA advocates assert that it is necessary to keep the human

out of the time-critical loop to achieve productivity and fuel-use gains.

We question that belief as well. AERA may well achieve 100 percent

productivity increases in the en route high and transition sectors, and

it may indeed facilitate more fuel-efficient air operations. But if the

controller work force almost doubles, as expected, by the time AERA

comes on-line, and AERA’s domain of applicability is limited to the

‘The Rand Corp., R-2698-FAA, November 1981
60 ● Review of the FAA 1982 National Airspace System Plan

57

simplest of sector types, its ultimate effect may hardly be felt, since the

actual ATC bottlenecks occur elsewhere. Further, greater fuel efficiency comes from many sources-some as simple as present-day relaxation

of procedural restrictions, some as complex as the planning modules of

AERA and Shared Control. AERA may meet the goals of ATC by 2000,

but the costs incurred along the way will be very great-in dollars, in

fundamental research that must be completed, and in restrictions on

the controller’s role.

Ultimately, the AERA scenario troubles us because it allows for few.

errors or missteps, The right choices have to be made at the right times,

or a failed AERA scenario would degrade to a more costly and delayed

version of the Baseline scenario. In the attempt to construct a totally

automated ATC control system, unacceptably high possibilities and

costs of failure overshadow the potential rewards of success, .

Our main conclusion is that such an overwhelming dependence on

technology is simply unnecessary. If the planned AERA scenario were

altered only slightly, it would be essentially equivalent to the Shared

Control scenario. All of its technical building blocks are present in

Shared Control:

. Air/ground datalink communication.

. Strategic planning (profile generation and alteration) and operator displays.

. Tactical execution.

. Track monitoring and alert.

Missing, however, is the right principle for piecing these building

blocks together. Under AERA, they would be fully integrated into a

single problem-solving system which extends its capabilities by infrequently requesting human action; under Shared Control, the building

blocks would themselves be extensions of human capabilities. Operationally, this shift in perspective requires two modifications of AERA

plans:

The state of the art in ATC problem-solving techniques does not

validate the minimal AERA human role; neither does established

knowledge about human limitations or capabilities in this domain,

Insisting that man be essentially automated out of such a critical control system is an unnecessarily high-risk approach.
App. B—Computer and Communication Technologies in FAA National Airspace System Plan . 61

58

If the system is designed to support him, we would expect the future

ATC specialist to take a very active and creative role in manipulating

his aiding modules. Safety could be assured by assigning the machine

primary responsibility for routine separation assurance tasks at the

lowest levels. The specialist should be responsible for comprehending

situations at high levels of abstraction and activating modules to meet

the ever-changing demands of those situations. He should be able to

adjust a module’s parameters and its relationships to other modules so

that instead of simply monitoring the machine’s preprogrammed sequence of instructions, he actually controls the outcome. He should be

given the authority to determine which operation the machine performs and which he performs. He should be given the opportunity to

learn all of this gradually and to influence the system’s design before

it is finalized.

This shift in perspective captures the spirit of this report. Specifications of module capabilities and their sequence of implementation are

best left to designers who are intimately familiar with the engineering

details. We have presented just one of many alternatives in which man

has a significant ATC role; the details of the system design need refinement and may indeed undergo great change in the process. For example, our Shared Control scenario suggests implementing digital

communications before providing any planning aids at all. Perhaps

events will dictate otherwise-a late DABS introduction and an early

development of automated planning techniques could reverse this sequence. Fielding a planning aid first as a stand-alone module would not

compromise the Shared Control scenario in any way. The essence of the

Shared Control scenario is reflected in its name-man and machine

must work together and share in the overall control function of ATC.

Our key concern is that the human specialist’s unique capabilities

be acknowledged and the technical uncertainties of an AERA-like system be recognized and dealt with before too much of the Baseline

scenario comes to pass. If this is not done, we risk relying solely on an

unproven, costly technology to meet the nation’s demands for ATC

service. We have shown not only that there is a feasible alternative, but

also that this alternative may result in lower costs, a higher level of

performance, and a more satisfying role for the personnel who will be

responsible for moving air traffic safely and smoothly.
Appendix C

OTA CONFERENCE ON THE

NATIONAL AIRSPACE SYSTEM PLAN

ATTACHMENT C-1: AGENDA AND LIST OF PARTICIPANTS

Agenda: OTA Conference on the

National Airspace System Plan,

Apr. 1-2, 1982

Thursday, Apr. 1

9:00-9:10

9:10-12:00

12:00-1:30

1:30-4:30

4:30-5:30

Welcoming Remarks and Introductions

Growth of Aviation

Summary of Working Group 1 and 2—H. Clark Stroupe

FAA Forecast Methods—David Lewis

Discussion:

Factors influencing aviation growth

Responsiveness of FAA plan to growth and need for services

Lunch

Guest Speaker: J. Lynn Helms

Administrator

Federal Aviation Administration

Implementation of FAA Plan

Summary of GAO Studies—Tony Csicseri

Discussion:

Technological risks

Implementation problems

Scheduling

Flexibility and preservation of options

Reception

Friday, Apr. 2

9:00-12:00 Effects on Airspace Users

Summary of Questionnaire Responses—Larry Jenney

Discussion:

Potential benefits and problems

Difficulties during transition

Implications of automation

Consolidation of facilities

12:00-1:30 Lunch

Guest Speaker: Philip J, Klass

Senior Avionics Editor

Aviation Week & Space Technology

62
App. C—OTA Conference on the National Airspace System Plan ● 6 3

1:30-3:30 Cost and Funding Issues

Summary of Questionnaire Responses—Larry Jenney

Impact of User Fees—David Lewis

Discussion:

User fees and other funding strategies

Operating and maintenance costs

Allocation of revenues

3:30-4:30 Summation and Concluding Remarks

Review of Key Issues

Recommendations for Additional Study

OTA Conference on the National

Airspace System Plan, Apr. 1=2, 1982

John L. McLucas, Chairman

President, Comsat World Systems

Ward Baker

Airline Pilots Association

Frederick Bradley, Jr.

Vice President

Citibank, N.A.

Samuel C. Colwell

Director, Market Planning

Fairchild Industries, Inc.

Barbara Corn

BD Systems, Inc.

Anthony Csicseri

U.S. General Accounting Office

Elwood T. Driver

Former Vice Chairman

National Transportation Safety

Thomas S. Falatko

Deputy for Transportation and

U.S. Air Force

Matthew Finucane

Director

Board

Civil Aviation

Aviation Consumer Action Project

Rod Gilstrap

Director

Flight Safety and Operations

Un~ted Air Lines -

William T. Hardaker

Assistant Vice President

Air Transport Association

William Horn, Jr.

National Business Aircraft Association

Victor J. Kayne

Senior Vice President

Technical Policy and Plans

Aircraft Owners and Pilots Association

David Lewis

Congressional Budget Office

John Leyden

Executive Director

Public Employees Department

AFL-CIO

Kingsley G. Morse

Chairman

Regional Airlines Association

Gilbert F. Quinby

Consultant

J. Donald Reilly

Executive Vice President

Airport Operators Council International

Harrison Rowe

Bell Laboratories

Crawford Hill Laboratory

Robert C. Seamans, Jr.

Professor of Environment and Public Policy

Massachusetts Institute of Technology

Robert Simpson

Flight Transportation Laboratory

Massachusetts Institute of Technology

H. Clark Stroupe

Vice President

Booz-Allen & Hamilton, Inc.

Richard W. Taylor

Vice President

Boeing Commercial Airplane Co.

David Thomas

Consultant

General Aircraft Manufacturers Association

Vincent Volpicelli

Supervising Engineer

Port Authority of New York and New Jersey
64 ● Review of the FAA 1982 National Airspace Plan 

ATTACHMENT C-2: SUMMARY OF QUESTIONNAIRE RESPONSES

Summary of Questionnaire Responses

Participants in the OTA Conference on the National

Airspace System Plan were asked to complete a questionnaire outlining their views on FAA’s proposed program of improvements in the ATC system. Responses

were received from 16 of the 25 participants. Replies

from others were promised but not available in time

for inclusion in this summary. For this reason, the

material presented here should not be interpreted as

representing the views of all conference participants.

Responses are summarized under headings that correspond to items in the questionnaire. In some cases,

the responses to related questions have been combined

because of the overlap in content. All items are presented in a common format—a brief characterization

of the replies as a whole followed by a few excerpts

to illustrate the variety of views and some of the particular points made by respondents.

It is not the purpose of this summary to suggest a

majority view or to attempt to frame what might be

construed as a “conference position. ” Rather, the document was used at the conference to provide participants with a preliminary indication of their colleagues’

views, with the object of furthering discussion on the

points to be addressed by the conference.

Growth

What are the prospects for growth and where is

it likely to occur?

Many respondents indicated that FAA’s forecasts of

aviation growth are too high. They foresaw little or

no growth in air carrier activity. They regarded commuter airlines and business aircraft as the sectors most

likely to experience significant growth in the future.

Excerpts:

— “I have been amazed at how constant the number of air carrier aircraft has been over the last

decade or so. With the growth of short haul/commuter airlines, I would expect the air carrier (fleet)

to continue about as is and the commuter and GA

(sectors) to experience a lot of growth.”

—“The FAA’s forecasts appear to be optimistic in

view of the current economic plight of the aviation industry . . . . The number of aircraft operations rather than passenger enplanements should

form the foundation for any improvements” (to

the system).

—“The FAA’s latest forecast of itinerant air carrier

aircraft operations at airports with FAA traffic

control appears reasonable . . . . They are becoming more reasonable with each annual update,

regarding passenger enplanements and air carrier

aircraft operations. ”

—“Demand placed on the system by the general aviation fleet could conceivably double by the year

2000. . . due to . . . continued growth in the

turbo-jet and turbo-prop and rotary-wing segments of the fleet. ”

—We view with some caution the (FAA) general

aviation projections, particularly in view of the

continually declining rates of production of small

aircraft and the economic and related factors responsible for this decline (fuel costs, interest rates,

student starts).

What factors are most likely to influence growth?

Virtually all respondents cited economic factors as

the key determinants of aviation growth. They did

not see aircraft or avionics technology per se as a major

factor. Many felt that the lack of airports or adequate

airport facilities could become a major constraint, and

several were concerned that regulatory restraints—notably airport restrictions—could slow GA expansion.

Excerpts:

— “In the past, the business cycle and economic

climate have influenced the demand for air travel

most heavily, and we see no basic change from

this correlation. ”

. “Business aviation growth will continue, but it

will never approach the large increases of 1978-

1979. . . . The low growth rate of 1979-1980 is

an indicator of how much the economy can affect the purchase of aircraft.”

— “Under deregulation, it is not clear whether they

(air carriers) will be financially able to continue

modernization. ”

—“We expect no major technology breakthrough

during the decade of the 1980’s that would again

revolutionize air travel. ”

—“Increased airway capacity and reduced separation standards are necessary, but they will be of

no avail if there is no place for the traffic to

go . . . . If more new airports are not in the planning stages in 1982, the planned sophistication of

the airway system will come to naught.”

—“The present restriction on flights at saturated airports will, if not alleviated, be a serious negative

factor.”
App. C—OTA Conference on the National Airspace System Plan . 65

National Airspace System Plan

Does the Plan adequately respond to the needs

of aviation?

One respondent had a succinct answer to the question: “Yes (finally ).” Indeed, nearly all respondents

replied affirmatively to the thrust of this question.

Some expressed concern, however, about the absence

of supporting detail in the NAS Plan.

Excerpts:

—“The FAA Plan is primarily a management document for the U.S. Government to handle what

they forecast will be a massive increase in aircraft

growth . . . . Because of my doubts concerning

the validity of the forecasts, I feel that the time

frames for equipment purchase and facility consolidation are highly suspect. ”

— “The FAA Plan represents an impressive planning

effort . . . . (But it) is incomplete as a vehicle for

truly evaluating whether it can satisfy the user’s

needs. The Plan describes primarily an ATC system framework (hardware, software, functional

capabilities), but does not describe either how the

system will operate or the potential benefits. ”

—The Plan “seems to give more a management

overview rather than the technical considerations”

that led to specific decisions.

—“General aviation, which shows the highest fleet

growth, may not be receiving benefits commensurate with their contribution. ”

—There seems to be a noticeable gap in meaningful

programs to increase capacity . . . at airports and

in the terminal airspace, particularly in highdensity areas. This element of overall aviation

system capacity is identified as a major constraint,

but major programs are not included.

What elements of the Plan pose the greatest technological risk?

Though they thought that the elements of technology in the NAS Plan are within the state of the art,

respondents expressed some concern about the integration of those elements and their impact on the people

who operate and use the ATC system. They singled

out two areas: 1) the design of a new computer system

(hardware and software) and 2) airborne communications links, namely the Mode-S transponder and TCAS

(Traffic Alert and Collision Avoidance System).

Excerpts:

— “The development of a host [replacement] computer which uses existing software from the 9020

programs with ‘minimal modifications’ sounds

promising, but . . . the lack of top-down structured design in the present computer software

(due to its evolutionary development) all add up

to an enormous and complex rehosting software

task. ”

— “The ability to design and transition to a new

ATC computer system which effectively utilizes

the human controller . . . [and] captures the advantages of higher orders of automation may be

the greatest risk. ”

—“The greatest technological risks involve the reliability of the system and the capability of the

human element to perform in the event of a system failure. ”

—“Mode S is fraught with potential problems because people will not want to get data out of a

black box unless they can check it by talking it

over with the man on the ground. ”

–(With Mode S and TCAS, ) “interference, multipath propagation, system architecture, (and) data

rate will all affect system performance. ”

What problems might be encountered in implementing the Plan?

Respondents foresaw several difficulties and felt that

the Plan does not adequately address questions of user

acceptance, operational safety, costs, and the implications of automation. Many also felt that managerial

problems would be encountered.

Excerpts:

— “Pilots will not trust new equipment without thorough checkout. ”

— “The greatest problem . . . will be one of a financial burden on the FAA and the aviation user

community. ”

–Automated En Route Air Traffic Control (AERA)

and the Mode S transponder appear to be little

more than concepts at this time. A great deal of

discussion needs to be carried on between the

users and the FAA to determine the basic designs

of these systems.

—“The extensive computer-to-computer conversations and black-box-to-black-box coordination . . . necessary in a computer decisionmaking process will require intricate communications

linkage and backup.”

—“The funding, management and political support

of a reduction in jobs and manned facilities of the

magnitude proposed will probably be the most

difficult to accomplish.”

—“With all or the majority of the funds coming

from the direct users of the system, unrealistic cost

projections, manifesting themselves in major

budget overruns . . . could threaten the entire

plan . . . . Only one implementation schedule has

been revealed. The FAA fallback position (if actual demand does not match the forecast and
66 ● Review of the FAA 1982 National Airspace System Plan

funding is too slow or too low or both) is not

discussed.”

Is the schedule realistic?

No consensus emerged. Though some thought the

schedule was workable, others considered it too slow

or too fast. There was also some criticism of FAA’s

failure to consider airport capacity and other restraining factors.

Excerpts:

—“It is realistic—if money is no object. However,

the matter of financing may change the schedule.”

—“The schedule is characteristically optimistic . . . . (Yet) this is clearly to be preferred from

a safety standpoint over having the system’s capacity expansion lag behind the demand.”

—’The proposed schedule, while optimistic, already

contains delays in availability of needed services, ”

—“The schedule may perhaps be too slow to keep

up with demands, even if the forecasts are on the

high side.”

—“It isn’t clear just how a 100 percent growth between 1980 and 2000 in aircraft operations and

passenger enplanements will be handled at the airports that are already saturated . . . . Very little

of the NAS Plan addresses (airport) capacity increases comparable to the (traffic) forecast. ”

—’The schedules as presented in the majority of the

programs are pie-in-the-sky; many of the programs have been a part of the FAA for many

years and delay has been a constant factor.”

—“Based on past experience . , . automation of new

concepts of the magnitude descibed in the Plan

may take at least twice as long as originally estimated. The Plan may be too ambitious since we

do not agree with the FAA projections of fleet size

for air carriers and commuters.”

What other options should be pursued?

Respondents provided a wide range of suggestions.

Some suggested changes in timing or tactics; others advocated putting more emphasis on airborne systems;

and a few recommended a fundamental reevaulation

of how ATC services are to be provided.

Excerpts:

—“From a strategic standpoint, the FAA plan is a

good one . . . . Program-by-program and

project-by-project, there will be a need for rethinking options.”

—“The FAA choices represent the best chances for

success with the fewest risks. Other possible

choices, such as the use of satellite technology for

navigation and position reporting, are excellent

candidates for succeeding systems and should be

kept in the forefront for test and evaluation. However, system improvements, as contained in the

Plan, should not be delayed for something that

might be better in the unknown future. ”

—“The 9020 computer should be upgraded . . . . A

greater exchange of information between facilities

and between FAA employees and the pilots is necessary . . . . We must slowly allow the computer . . . to assist the controller in making his

decisions.”

—“A competitive, single (computer) procurement

with demonstration prior to award is one alternative that should be investigated. ”

–“Major technology options to be pursued should

include utilization of airborne data processing

capability in the development of such programs

as integrated flow management and automated en

route ATC (AERA) . . . . Our concern is with the

apparent lack of involvement of tie-in of the

‘smart airplane’ in the FAA’s automation plan. ”

—“Priority should be given to completion of the FSS

(Flight Service Station) modernization, which has

safety connotations. ”

—“The FAA communication plan envisions creating

what is in effect a nationwide long-lines network . . . . Will this really be cheaper than buying communication services?”

—“Look at feasibility of converting (ATC functions)

to private corporation concept and compare overall costs and efficiency. ”

Effects on Users

What benefits are likely to result from the plan?

Respondents agreed that a major benefit of the new

ATC system would be the ability to handle more aircraft safely and efficiently. Major benefits would accrue to air carriers and business aviation. The magnitude and importance of the benefits to private GA were

not perceived to be as clear.

Excerpts:

—“Greater efficiency and safety of operations are

major benefits to the users. Increased capacity to

handle growth must be pursued when the alternative would be to constrain growth. ”

—“Air carrier operations will benefit . . . in terms

of improved safety, flight efficiency and capacity. However, these benefits will be small until the

post-1990 time period.”

—“Increased automation, distributed processing,

remote maintenance monitoring, and air-to-air

plus air-to-ground data links will make the navigation and air traffic control system substantially more stable and reliable.”

—“Improvement in dissemination of weather information, less labor-intensive ATC system (and) in-
creased capacity of ATC system—if everything

works out as planned. ”

—“Any improvements in the ground computer capability that would allow the business flyer to use

this equipment to its maximum usage would be

welcomed . . . If the new system would authorize

the (GA) pilot with the proper input and output

devices to operate directly into the WX (weather)

computer and to file his flight plan directly into

the 9020 (computer) or its replacement, it would

be most helpful.”

. “The increased safety/efficiency resulting from

high computer reliability will benefit all

users . . . . The major benefit will be the eventual availability of adequate ATC computing capability and Mode-S digital data link.”

Identify potential problems and steps that might

mitigate them.

Though enthusiastic about technological improvements, some respondents indicated skepticism

that higher user fees would be offset by commensurate

increases in services and benefits. Because the new

system would be more automated, some were concerned that system users might lack confidence in ATC

operation.

Excerpts:

—“Transition . . . to a point 10 or 15 years from

now where all these benefits of new technology

are available will be difficult. ”

—There would be “less personal interface between

users of the system and those managing and controlling it. ”

—“Emergency operation in case of equipment failure

seems not to have been discussed much in the

(NAS) Plan.”

— “The cost of dual carriage of equipment and the

problems of space and weight of this equipment

in some aircraft appear to be the only penalties

inherent in (the) PIan. ”

— “Increasingly sophisticated avionics required for

operation at certain high-density controlled airports and in certain airspace (TCA’s) will restrict

the operation of general aviation users who do

not make the investment. ”

—“It will be a defensive move for many people—

buy this new equipment or be denied access to

the airspace. There could be confusion between

ILS and MLS—one more switch can be set in the

wrong position. ”

–“Consideration should be given to retaining full

ILS service . . . . The full MLS program should

be subject to review , . . after suitable operational

experience is obtained . . . . Automatic altitude

reporting and Mode-S transponders should be

mandated as being essential to safe and efficient

operation of the ATC system. ”

—“The result will be more restrictions in operations

either through operational procedures/requirements or required equipment. ”

–(The Plan should provide ways) “to accommodate

all segments of aviation in the system by segregating operations based on performance capabilities. ”

Cost and Funding

How should costs be allocated among the Government and system users?

Respondents’ views seemed to be divided among

three different approaches. Some favored reestablishment of the Airport and Airways Trust Fund, with

some adjustment of tax rates to achieve parity of cost

recovery. Others suggested user fees based on aircraft

characteristics or avionics equipment. A third view

was that fees should be levied in proportion to the use

made of, or the burden placed on the ATC system.

Excerpts:

— “The revenue measures which existed under the

Airport and Airway Revenue Act of 1970 should

be reinstituted.”

— “First, the national interest portion must be determined and subtracted. Failure to do this is what

discredited past user charges.”

—“Whatever (funding) mechanism is adopted

should . . . not discourage people from using the

system. ”

—“There is a real danger that funding the (NAS

PIan) . . . to a reported 85 percent would have

a regressive effect on the very growth in demand

that justifies the (new) system. ”

—“The business community (air carriers/corporate

aircraft) would pass the cost on to the passenger

or consumer; general/private or nonbusiness

aviation would absorb the cost by not flying as

much or would cease flying altogether; the cost

to the military would come from an increased

budget (taxes).”

—“It seems apparent that the general aviation contribution of roughly 5 percent of the cost, as is

now the case, is low and should be increased. ”

— “The airport ‘head tax’ will never be tolerated by

the traveling public.”

—“Taxes could also be assessed on the purchase of

advanced avionics equipment. ”

—(Charges should be levied) “depending on the percentage that various groups utilize the system. ”
68 ● Review of the FAA 1982 National Airspace System Plan

How should revenues from user charges be

allocated?

Several respondents stressed the importance of

employing user fees to cover the cost of capital improvements in the ATC system. Some indicated that

surpluses should be avoided, since they would indicate

that the fees are too high and therefore would be likely to restrict access to the system. There was wide

disagreement about whether operating and maintenance costs of the ATC system should be covered,

wholly or partly, by user fees.

Excerpts:

—“The FAA was created in the public interest, and

the public should pay for its operation. If the users

are to pay for everything, then we should consider abolishing the FAA. ”

—“Taxes should be levied no higher than necessary

to support the program and (should be) tied to

a commitment to carry it out. ”

—“User charges should only be allocated to the Airport and Airway Trust Fund.” (The FAA should)

“use the Trust Fund for its intended purpose and

prevent accrual of a surplus for other purposes. ”

—“ATC system improvements and R&D should receive the bulk of-user charges. A substantial portion should be used for operation and maintenance. ”

—Trust Fund surpluses “should be applied to the

costs of operating and maintaining the system. ”

—User fee allocations: “System improvements, 50

percent; R&D, 20 percent; airports, 10 percent;

operations and maintenance, 20 percent. ”

–“(User fees) should be allocated to cover all

facilities and equipment and research and development costs, roughly 50 percent of the operations and maintenance costs, and full funding of

ADAP.”

—“A substantial portion should be allocated as aid

to airports. None of the user fees should be used

for operations and maintenance.”

ATTACHMENT C-3: A SUMMARY OF THE CONFEREES’ VIEWS

Implementation of the FAA Plan—

A Summary of the Conferees’ Views

at the 1982 OTA Conference

Technological Risks

The FAA Plan contains few technological risks.

Most of the elements of the plan reflect the result of

extensive use experiences or long-term development.

Modes S and TCAS were endorsed. General Aviation implementation of new transponders should be

voluntary to the extent possible, consistent with system

safety standards.

Some elements of the plan are “demand independent, ” and constant efforts to improve system safety are

in this category.

A cornerstone of the plan is and should be the immediate initiation of a program to replace the present

outmoded ATC automation system with modern software hardware of greater capacity, reliability and

flexibility.

Making the transition between the present limited

system and a new computer system presents the greatest challenge and risks. If the lives of the current computers are extended unduly, maintenance becomes

more difficult and capacity for new functions is

limited. If present software is “rehosted” to new computers which are to be used during the next two

decades, the choice of computers may limit future systems development. Rehosting to interim “throw away”

computers (emulators) has been suggested as a method

of providing adequate capacity during the new software development stage without freezing the computer

technology or architecture now.

The best way to proceed is a judgment call, and is

a matter which this group does not have time to

resolve. The FAA judgment is to proceed with a “final”

computer replacement selection, and we suggest that

good answers will be available only after bids on their

proposals are received.

Implementation Problems

The ability of FAA to implement a plan of this magnitude was discussed. Considering the ultimate responsibility of FAA for the safety of those using the system,

and the prior success of it and other agencies, such as

the National Aeronautics and Space Administration

and the military services, in implementing major programs, it was the consensus that FAA should manage

the program and obtain necessary additional management and engineering assistance from industry early

in the program.

The plan relies heavily on consolidation of manned

facilities to achieve economies of scale. Removal of

major Government facilities from communities is often

difficult, and aviation groups should support consolidations wherever it is shown that costs can be reduced

without degrading services.
App. C—OTA Conference on the National Airspace System Plan . 69

Scheduling

FAA has not presented sufficient engineering data

to assess the proposed schedules. However, the need

to rebuild the system and reduce its manpower intensity indicates there should be no delay in starting on

the plan.

Flexibility and Preservation of Options

There is good correlation among independent forecasts of trunk air carrier activities, but less confidence

in detail of General Aviation forecasts. Implementation of plan should be flexible and adapted to real

growth in demand.

The plan appears to provide flexibility to accommodate some changes in direction, such as increased

use of cockpit displays and various types of airborne

navigation devices, but is not susceptible to such basic

changes as whether to replace computers and provide

more automated functions if manpower intensity is to

be reduced.

Other Concerns

Other concerns are:

1. Airports: A companion airport development program is required. Airport capacity in major communities is the ultimate limitation.

2. Safety: The plan does not specify the most urgent

safety needs in a priority manner, nor is this

needed if adequate funding is provided. However,

if funding becomes critical, each year’s budget

must be examined closely to avoid safety items

being dropped or deemphasized. Priority determination must fully consider the relationship and

interdependency of the separate elements. Failure

to do so could adversely affect other systems

within the plan if those systems were somehow

dependent upon the element in question. A thorough systems look is necessary.

3.

4.

54

6.

Long-Range Funding: Unless adequate long-range

funding is assured, by both user charges and Government commitment to its share, there is little

prospect that the improvements contemplated

will be accomplished.

Demand: Forecast demands may be wrong, and

planned capacity may either not meet—or exceed—demands. It may be necessary to adjust

schedules to reflect actual demand experience, but

the basic concept of providing more automation

should be pursued regardless of precise rate of

growth.

Man-Machine Interface: The new sector suite

concept pushes reliance on automation much further than current practice. Thus, controllers can

handle more traffic per individual, but their

duties and responsibilities would be changed significantly. There is little technical risk in the sector suite concept, but care is needed in designing

man-machine interfaces to achieve controller efficiency without requiring extraordinary effort or

skill.

Wake Vortex: Increased emphasis should be

given to solving wake vortex generation and detection so that acceptance rates can be increased.

Summary

Despite inevitable flaws in the detail elements of the

plan, the conference agreed that it merits general endorsement and strong support for long-term funding

as a specific element of legislation. One basis for this

position was that the proposals within the plan are

directed toward the resolution of past and current

problems—safety, economics, and reliability— as well

as anticipated growth, demand, safety, and reliability problems. There was concern over the proposed use

of user-funded trust funds to pay a very high percentage of the operations and maintenance charges of

FAA, but this issue must be resolved in the appropriate

congressional committees.