oversight

Air Traffic Control: Complete and Enforced Architecture Needed for FAA Systems Modernization

Published by the Government Accountability Office on 1997-02-03.

Below is a raw (and likely hideous) rendition of the original report. (PDF)

                 United States General Accounting Office

GAO              Report to the Secretary of
                 Transportation



February 1997
                 AIR TRAFFIC
                 CONTROL
                 Complete and
                 Enforced Architecture
                 Needed for FAA
                 Systems Modernization




GAO/AIMD-97-30
      United States
GAO   General Accounting Office
      Washington, D.C. 20548

      Accounting and Information
      Management Division

      B-271527

      February 3, 1997

      The Honorable Federico Peña
      Secretary of Transportation

      Dear Mr. Secretary:

      This report describes the need for a Federal Aviation Administration (FAA)-wide systems
      architecture in modernizing Air Traffic Control (ATC), and assesses FAA’s efforts to develop and
      utilize one.

      This report contains recommendations to you. The head of a federal agency is required by 31
      U.S.C. 720 to submit a written statement on actions taken on these recommendations. You
      should send your statement to the Senate Committee on Government Affairs and the House
      Committee on Government Reform and Oversight within 60 days after the date of this report.
      You must also send the written statement to the House and Senate Committees on
      Appropriations with the agency’s first request for appropriations made over 60 days after the
      date of this report.

      We are providing copies of this report to interested congressional committees and
      subcommittees, the Director of the Office of Management and Budget, the Administrator of the
      Federal Aviation Administration, and other interested parties. Copies will also be made
      available to others upon request. Please call me at (202) 512-6412 if you have any questions
      concerning the report. Other contributors to this report are listed in appendix III.

      Sincerely yours,




      Dr. Rona B. Stillman
      Chief Scientist for Computers
        and Telecommunications
Executive Summary


             Effectively and efficiently designing and constructing a building requires a
Purpose      complete blueprint that defines the building’s features, functions, and
             systems as well as how these components interrelate and how they are to
             be crafted, including applicable building codes, rules, and standards.
             Effective and efficient modernization of an organization’s computer
             systems requires no less. Accordingly, the Congress has emphasized in law
             the importance of agencies’ Chief Information Officers (CIO) developing
             and implementing system blueprints, commonly called architectures, to
             guide current and future systems development and evolution.1

             Because of the size, complexity, and importance of FAA’s air traffic control
             (ATC) modernization, we reviewed it to determine (1) whether FAA has a
             target architecture(s), and associated subarchitectures, to guide the
             development and evolution of its ATC systems; and (2) what, if any,
             architectural incompatibilities exist among ATC systems, and the effect of
             these incompatibilities.


             A systems architecture is a blueprint to guide and constrain the
Background   development and evolution (i.e., maintenance) of a collection of related
             systems. A systems architecture can be viewed as having both a logical
             and technical component. At the logical level, the architecture provides a
             high-level description of the organizational mission being accomplished,
             the business functions being performed and the relationships among
             functions, the information needed to perform the functions, and the flow
             of information among functions.

             At the technical level, the architecture provides the rules and standards
             needed to ensure that the interrelated systems are built to be
             interoperable,2 portable,3 and maintainable. These include specifications
             of critical aspects of the component systems’ hardware, software,
             communication, data, security, and performance characteristics.

             Since 1981, FAA has spent about $23 billion to modernize its aging air
             traffic control (ATC) system. It plans to spend about $11 billion more
             through the year 2003, with additional systems to be undertaken through
             the year 2015. Through this enormous investment, FAA plans to put in place

             1
              The 1996 Clinger-Cohen Act, P. L. No. 104-106, section 5125, 110 Stat. 684 (1996).
             2
              Interoperability is the ability of disparate systems to work together efficiently and effectively over a
             network.
             3
              Portability is the degree to which a computer program can be transferred from one hardware
             configuration and/or software environment to another.



             Page 2                                                           GAO/AIMD-97-30 Air Traffic Control
                   Executive Summary




                   a vast “system of systems” that will allow it to safely and efficiently keep
                   pace with burgeoning traffic volumes. Successfully doing so, however,
                   requires that interdependent ATC systems are architecturally consistent
                   (i.e., can work together effectively and efficiently, and be developed,
                   operated, and maintained cost effectively).

                   FAA’sAssociate Administrator for Research and Acquisitions is primarily
                   responsible for managing ATC systems acquisitions, while ATC systems
                   operations and maintenance responsibility falls under FAA’s Associate
                   Administrator for Air Traffic Services.


                   FAA lacks a complete systems architecture, or overall blueprint, to guide
Results in Brief   and constrain the development and maintenance of the many interrelated
                   systems comprising its ATC infrastructure. To FAA’s credit, it is developing
                   one of the two principal components of a complete systems architecture,
                   namely the “logical” description of FAA’s current and future concept of ATC
                   operations as well as descriptions of the ATC business functions to be
                   performed, the associated systems to be used, and the information flows
                   among systems. However, FAA is not developing, nor does it have plans to
                   develop, the second essential component—the ATC-wide “technical”
                   description which defines all required information technology and
                   telecommunications standards and critical ATC systems’ technical
                   characteristics (i.e., hardware, software, communications, data
                   management, security, performance).

                   The lack of a complete and enforced systems architecture has permitted
                   incompatibilities among existing ATC systems and will continue to do so
                   for future systems. Overcoming these incompatibilities means “higher than
                   need be” system development, integration, and maintenance costs, and
                   reduced overall systems performance. To illustrate, because there are no
                   specified standard data communication protocols,4 existing systems have
                   implemented different communication protocols. To make them work
                   together, expensive interfaces (hardware and software) acting as protocol
                   translators are required, complicating and slowing communications.
                   Similarly, because there are no standards for programming languages or
                   open systems, ATC systems’ software has been written in many different
                   application programming languages, often exhibiting proprietary system
                   characteristics. This not only increases software maintenance costs but
                   also effectively precludes sharing software components among systems.

                   4
                    Data communication protocols are sets of rules that govern communications among computer
                   systems.



                   Page 3                                                    GAO/AIMD-97-30 Air Traffic Control
Executive Summary




For example, two ATC systems perform flight data processing functions,
one for traffic in the continental U.S. and the other for traffic over the
oceans. Since about 40 percent of the functions that these systems
perform are the same, their replacements could potentially share a
significant amount of software, avoiding duplicative development and
saving money. However, without a technical architecture specifying the
information technology standards and rules, the opportunity to share
software will likely be lost.

In some cases, system incompatibilities exist because the technology and
standards now available to permit system integration and interoperability
did not exist or were only emerging when the systems were designed and
developed. However, other system incompatibilities are the result of FAA’s
failure to adopt and effectively enforce a technical architecture. By failing
to formulate a complete systems architecture and using this to guide the
development and evolution of its modernized systems, FAA permits and
perpetuates inconsistency and incompatibility. As a result, future ATC
system development and maintenance will continue to be more difficult
and costly than it need be and system performance will continue to be
suboptimal.

FAA’s management structure for developing, maintaining, and enforcing an
ATC systems architecture is not effective. The Office of Systems
Architecture and Investment Analysis, which reports to the Associate
Administrator for Research and Acquisitions, is responsible for developing
and maintaining the logical ATC systems architecture, but no FAA
organizational entity is responsible for developing and maintaining the
technical ATC architecture. As a result, there is no complete technical
architecture and no coordinated effort underway to produce one.
Additionally, FAA does not effectively enforce the only ATC architecture it
has, the NAS (logical ATC) architecture. Instead, processes now in place at
FAA permit the acquisition of architecturally non-compliant systems
without special waiver of architectural standards. Until FAA assigns
responsibility and authority and provides resources for developing,
maintaining, and enforcing a complete ATC systems architecture to a single
FAA organizational entity, FAA will continue to develop systems that require
more effort and cost more than is necessary.




Page 4                                         GAO/AIMD-97-30 Air Traffic Control
                          Executive Summary




Principal Findings

An Architecture Is the    As systems have become increasingly complex and critical, the need for a
Centerpiece of Sound      systems architecture to ensure interoperability and cost effective
Systems Development and   maintenance has been generally recognized. For example, the Software
                          Engineering Institute at Carnegie Mellon University advocates systems
Maintenance               architectures to guide systems design and implementation. Additionally,
                          leading private and public sector organizations are using systems
                          architectures to guide mission-critical system acquisition, development,
                          and maintenance.


FAA Is Developing a       FAA is currently developing a logical ATC architecture as part of its National
Logical Architectural     Airspace System (NAS)5 architecture. Among other things, the NAS
Component for ATC         architecture describes FAA’s current and future concept of ATC operations,
                          requirements in terms of business functions to be performed, associated
Modernization and         systems to be used, relationships among these functions and systems,
Evolution                 information needed to perform these functions, and flow of information
                          among the functions and systems. This high-level systems blueprint also
                          provides a roadmap, or transition plan, for its ATC systems over a 20-year
                          period.


FAA Lacks a Technical     FAA lacks the second component of a systems architecture, the technical
Architectural Component   architecture that defines the standards and rules that will be used to
to Guide and Constrain    implement the logical architecture. The NAS architecture explicitly states
                          that “it is not intended to define detailed performance, characteristics, or
ATC Modernization and     interfaces of physical systems.” Instead, FAA is allowing each of the 10 ATC
Evolution                 system development teams to choose these characteristics for its systems
                          independently.

                          Technical architecture guidance is vital in ensuring the proper integration
                          of FAA’s many interdependent systems and simplifying system
                          maintenance. Despite this, 7 of the 10 ATC modernization systems
                          development teams that are developing new systems are doing so without
                          a technical architecture. Moreover, although the other three are
                          cooperatively developing similar architectures for their systems, these


                          5
                           FAA’s Pilot/Controller Glossary defines the NAS as the common network of U.S. airspace; air
                          navigation facilities, equipment, and services; airports or landing areas; aeronautical charts,
                          information, and services; rules, regulations, and procedures; technical information; and manpower
                          and material. Included are system components shared jointly with the military.



                          Page 5                                                       GAO/AIMD-97-30 Air Traffic Control
                           Executive Summary




                           architectures are not completely compatible, and the incompatibilities are
                           not justified by careful, documented analysis. For example, all three
                           architectures specify C and C++ as acceptable programming languages,
                           but one architecture also specifies Ada as an acceptable language. Further,
                           one technical architecture specifies the ethernet protocol, while another
                           specifies the Fiber Distributed Data Interface (FDDI) protocol. These two
                           protocols are not compatible.

                           At the same time, still other FAA organizations are independently
                           attempting to develop pieces of a technical architecture (e.g., software
                           guidance, security guidance), but these efforts neither individually nor
                           collectively constitute a complete ATC-wide technical architecture. Without
                           a single, unified technical architecture, compatibility and interoperability
                           across and among all ATC systems is highly unlikely.


Without a Technical ATC    A technical architecture specifies the information technology and
Architecture, Costly       communication standards that will be used to build systems, including
System Incompatibilities   communication protocols and programming languages, and facilitates the
                           migration to compatible, vendor-independent operating environments. A
Have Resulted and Will     vendor-independent environment is one whose critical interfaces and
Continue                   characteristics are in the public domain (i.e., not unique to a particular
                           vendor or group of vendors). Because FAA developed its ATC systems
                           without a technical architecture and relies upon vendor-unique
                           environments, it continues to spend time and money to overcome system
                           incompatibilities and may lose opportunities to share software
                           components among systems and avoid duplicative development and
                           maintenance.

                           One example is the 30-year-old Host Computer System, which is the
                           centerpiece of ATC operations.6 This system receives data from numerous
                           other systems, including aircraft surveillance radars and weather detection
                           systems, and processes it for use by controllers in tracking aircraft. If all of
                           these feeder systems used standard, architecturally defined
                           communications protocols and data formats, then there would be no need
                           to convert protocols and data formats for the Host. However, with no
                           unifying technical architecture, these feeder systems use a number of
                           different, incompatible communication protocols and data formats that
                           must be converted into formats understandable by the Host. To perform
                           this extensive conversion, FAA spent over $38 million to acquire a


                           6
                            FAA plans to begin replacement of the Host Computer System in fiscal year 1999.



                           Page 6                                                       GAO/AIMD-97-30 Air Traffic Control
                           Executive Summary




                           dedicated system, the Peripheral Adapter Module Replacement Item
                           (PAMRI).7 Additionally, it spends millions annually to maintain PAMRI.8

                           Another example of suboptimization caused in part by the absence of a
                           technical architecture is the proliferation of ATC systems’ application
                           programming languages. Currently, software applications associated with
                           54 ATC systems are written in 53 programming languages. Software written
                           in multiple languages is more difficult and expensive to maintain because
                           it requires more training and support software for programming staff.
                           Without a technical architecture limiting language choices, FAA continues
                           to introduce additional languages as new systems are developed, which
                           complicates maintenance even further and drives up its costs.

                           Incompatibilities among ATC systems also preclude software reuse, which
                           could potentially save systems development and maintenance time and
                           money. Specifically, some ATC systems perform like or similar functions,
                           each in a different airspace environment. For example, FAA officials told us
                           that about 40 percent of the functions performed as part of en route
                           airspace flight data processing (FDP) are identical to functions performed
                           in oceanic airspace FDP. However, without a technical architecture
                           specifying the information technology standards and rules, the oceanic
                           and en route replacement systems are not likely to implement common
                           standards and the opportunity to share software components will be lost.


FAA Lacks an Effective     If a systems architecture is to be effectively developed, maintained, and
Management Structure for   enforced, some organizational entity must (1) be assigned the
Developing and Enforcing   responsibility and held accountable for doing so, (2) be given sufficient
                           resources to accomplish the task, (3) have expertise in information
an ATC Systems             technology, and (4) have organizational and/or budgetary authority over
Architecture               all systems development and maintenance activities. One model for
                           implementing this is embodied in the Clinger-Cohen Act, which requires
                           that major federal departments and agencies establish CIOs that report to
                           the department/agency head and are responsible for developing,
                           maintaining, and facilitating the implementation of systems architectures.

                           FAA does not have an effective management structure for developing,
                           maintaining, and enforcing a logical systems architecture. An organization

                           7
                            This cost does not include FAA internal costs (e.g., project management, testing) associated with
                           acquiring PAMRI because FAA was unable to provide these costs.
                           8
                            FAA could not provide the full cost of maintaining PAMRI. Instead, FAA officials stated that about
                           $200,000 is spent annually to maintain PAMRI hardware, and about $500,000 is spent annually to
                           maintain PAMRI software at three sites. However, they could not provide the annual cost to maintain
                           PAMRI software at the other 26 sites where PAMRI is operational. We did not evaluate these costs.


                           Page 7                                                        GAO/AIMD-97-30 Air Traffic Control
                  Executive Summary




                  under the Associate Administrator for Research and Acquisitions is
                  responsible for developing and maintaining FAA’s logical architecture.
                  However, this office is not responsible for enforcing the logical
                  architecture (nor could it effectively do so because it has no budgetary or
                  organizational authority over the teams developing and maintaining ATC
                  systems). With no organization in FAA responsible for enforcing a logical
                  systems architecture, FAA has attempted to encourage use of the logical
                  architecture through its investment process, which stipulates that
                  architectural conformance be considered as one of four criteria before an
                  ATC system is approved for funding. This process does not ensure
                  architectural conformance since noncompliant ATC projects could be
                  funded (on the basis of the other three criteria) without an effective
                  waiver process.

                  FAA also lacks an effective management structure for developing,
                  maintaining, and enforcing a technical ATC systems architecture. No
                  organization in FAA is responsible for the technical ATC architecture.
                  Instead, FAA has permitted a “hodge podge” of independent efforts
                  scattered across its ATC modernization organization to emerge with no
                  central guidance and coordination. As a result, there is no ATC-wide
                  technical architecture, and it is unlikely that FAA will produce one in the
                  near future.

                  Until the authority, responsibility, and resources to develop, maintain, and
                  enforce a complete ATC systems architecture is clearly assigned to a single
                  FAA organizational entity, FAA will continue to build incompatible and
                  unnecessarily expensive and complex ATC systems.


                  GAO recommends that the Secretary of Transportation direct the FAA
Recommendations   Administrator to ensure that a complete ATC systems architecture is
                  developed and enforced expeditiously and before deciding on the
                  architectural characteristics for replacing the Host Computer System.

                  GAO  also recommends that the Secretary of Transportation direct the FAA
                  Administrator to establish an effective management structure for
                  developing, maintaining, and enforcing the complete ATC systems
                  architecture. Specifically, the Administrator should (1) assign the
                  responsibility and accountability needed to develop, maintain, and enforce
                  a complete ATC systems architecture to a single FAA organizational entity,
                  (2) provide this single entity with the resources, expertise, and budgetary
                  and/or organizational authority needed to fulfill its architectural



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                       Executive Summary




                       responsibilities, and (3) direct this single entity to ensure that every ATC
                       project conforms to the architecture unless careful, thorough, and
                       documented analysis supports an exception. Given the importance and the
                       magnitude of the information technology initiative at FAA, GAO
                       recommends that a management structure similar to the department-level
                       CIOs as prescribed in the Clinger-Cohen Act be established for FAA.



                       Department of Transportation (DOT) and FAA officials generally agreed with
Agency Comments        GAO’s conclusions and recommendations, which require FAA to define and
and GAO’s Evaluation   enforce a complete ATC-wide systems architecture. At the same time,
                       however, the officials stated that (1) FAA’s informal mechanisms for
                       attaining system compatibility (e.g., informal communication among
                       system development teams and circulation of individual system
                       specifications among these teams for review and comment) are sufficient
                       and are working well; and (2) the architectural definition efforts underway
                       within both individual development teams and these teams’ parent
                       organizations, which are described in this report, will effectively augment
                       these informal processes.

                       The many examples provided in this report in which FAA incurs added
                       costs to compensate for system incompatibilities arising from the lack of
                       an ATC architecture provide clear evidence that FAA’s informal mechanisms
                       have been neither sufficient nor have been working well; and there is no
                       logical rationale to support or explain the position that the efforts of the
                       individual teams will somehow coalesce into an effective approach to
                       ATC-wide architectural definition and enforcement. It is clear that
                       effectively modernizing a system of systems as technologically complex,
                       expensive, interdependent, and safety-critical as the ATC system requires
                       more than stovepipe architectures linked and enforced by informal
                       communications. Accordingly, GAO strongly recommends that FAA formally
                       define and enforce an ATC-wide systems architecture.




                       Page 9                                        GAO/AIMD-97-30 Air Traffic Control
Contents



Executive Summary                                                                                  2


Chapter 1                                                                                         14
                        Overview of ATC                                                           14
Introduction            Objectives, Scope, and Methodology                                        30

Chapter 2                                                                                         32
                        Systems Architectures Have Emerged as the Centerpiece of                  32
Systems Architecture      System Development Programs
Overview                Overview of a Systems Architecture’s Content                              33

Chapter 3                                                                                         35
                        FAA Is Making Good Progress in Defining a Logical ATC Systems             35
Lack of a Complete        Architecture
ATC Systems             FAA Has No Technical Systems Architecture                                 40
                        Lack of a Technical Systems Architecture Means Costly System              44
Architecture Impacts      Incompatibilities
ATC Modernization’s     Conclusions                                                               48
Cost and Performance    Recommendation                                                            48
                        Agency Comments and Our Evaluation                                        48

Chapter 4                                                                                         50
                        FAA Lacks an Effective Management Structure to Develop,                   50
FAA Lacks an              Maintain, and Enforce a Systems Architecture
Effective Management    Conclusions                                                               55
                        Recommendation                                                            55
Structure and Process   Agency Comments and Our Evaluation                                        55
to Develop and
Enforce a Systems
Architecture
Appendixes              Appendix I: Simplified Block Diagrams for the Near-Term and               56
                          Mid-Term En Route Centers’ Systems Environment
                        Appendix II: Architectural Characteristics of Current and                 64
                          Near-Term Key Enroute Systems
                        Appendix III: Major Contributors to This Report                           65

Figures                 Figure 1.1: ATC Facilities That Control Aircraft                          18
                        Figure 1.2: ATC Infrastructure Is a Complex System of Systems             22




                        Page 10                                    GAO/AIMD-97-30 Air Traffic Control
Contents




Figure 1.3: ATC Modernization and Maintenance Organizational                28
  Chart
Figure 2.1: Key Logical and Technical Components of A Systems               34
  Architecture
Figure 3.1: NAS Architecture Air Traffic Services, Business Areas,          39
  Functional Areas, and Related Systems
Figure 3.2: Architecture Guidance Used by the 10 IPTs to Guide              43
  Ongoing and Future Development
Figure 4.1: Office of Systems Architecture and Investment                   52
  Analysis’ Relative Organizational Position
Figure I.1: Near-Term Environment                                           56
Figure I.2: Mid-Term Environment                                            60

Abbreviations

AAS             Advanced Automation System
AND             Office of Communication, Navigation, and Surveillance
                      Systems
AOAS            Advanced Oceanic Automation System
ARA             Associate Administrator for Research and Acquisitions
ARINC           Aeronautical Radio Incorporated
ARTS            Automated Radar Terminal System
ATC             air traffic control
ATCSCC          Air Traffic Control System Command Center
ATM             Air Traffic Management
ATS             Associate Administrator for Air Traffic Services
AUA             Office of Systems Development
CIO             Chief Information Officer
CIP             Capital Investment Plan
CSA             corporate systems architecture
CTAS            Center TRACON Automation System
DOT             Department of Transportation
DSR             Display System Replacement
EDARC           Enhanced Direct Access Radar Channel
FAA             Federal Aviation Administration
FDDI            Fiber Distributed Data Interface
FDP             flight data processing
GPS             Global Positioning System
HCS             Host Computer System
HID/LAN         Host Interface Device/Local Area Network
IPT             Integrated Product Team
NAS             National Airspace System
NAS-DD-1000     NAS Level 1 Design Document


Page 11                                      GAO/AIMD-97-30 Air Traffic Control
Contents




NAS-SR-1000   NAS System Requirements Specification
NAS-SS-1000   NAS System Specification
NIMS          NAS Infrastructure Management System
ODAPS         Oceanic Display and Planning System
PAMRI         Peripheral Adapter Module Replacement Item
RE&D          Research, Engineering, and Development
SE-CMM        Systems Engineering Capability Maturity Model
SEI           Software Engineering Institute
SQL           Structured Query Language
STARS         Standard Terminal Automation Replacement System
TMS           Traffic Management System
TRACON        terminal radar approach control
WAAS          Wide Area Augmentation System




Page 12                                 GAO/AIMD-97-30 Air Traffic Control
Page 13   GAO/AIMD-97-30 Air Traffic Control
Chapter 1

Introduction


                  The Federal Aviation Administration’s (FAA) primary mission is to ensure
                  safe, orderly, and efficient air travel in the national airspace. FAA’s ability
                  to fulfill this mission depends on the adequacy and reliability of the
                  nation’s air traffic control (ATC) system, a vast network of computer
                  hardware, software, and communications equipment.1 Sustained growth in
                  air traffic and aging equipment have strained the current ATC system,
                  limiting the efficiency of ATC operations. This pattern is likely to continue
                  as the number of passengers traveling on U.S. airlines is expected to grow
                  from about 580 million in 1995 to nearly 800 million by 2003, an increase of
                  38 percent.

                  To address these trends, in 1981 FAA embarked on an ambitious ATC
                  modernization program. FAA estimates that it will spend about $20 billion
                  to replace and modernize ATC systems between 1982 and 2003. Our work
                  over the years has chronicled many FAA failures in meeting ATC projects’
                  cost, schedule, and performance goals.2 As a result, we designated FAA’s
                  ATC modernization as a high-risk information technology initiative in our
                  1995 report series on high-risk programs.3


                  The ATC system of the late 1970s was a blend of several generations of
Overview of ATC   automated and manual equipment, much of it labor-intensive and obsolete.
                  In addition, FAA forecasted increased future demand for air travel brought
                  on by airline deregulation of the late 1970s. At that time, FAA recognized
                  that it could increase ATC operating efficiency by increasing automation. It
                  also anticipated that meeting the demand safely and efficiently would
                  require improved and expanded services, additional facilities and
                  equipment, improved work force productivity, and the orderly
                  replacement of aging equipment. Accordingly, in December 1981, FAA
                  initiated its plan to modernize, automate, and consolidate the existing ATC
                  system by the year 2000.

                  This ambitious modernization program includes the acquisition of new
                  radars and automated data processing, navigation, and communication
                  equipment in addition to new facilities and support equipment. The
                  modernization, including new systems, facility upgrades, and support
                  equipment is now estimated to cost over $34 billion through the year 2003.

                  1
                   The ATC system is a major component of the National Airspace System (NAS).
                  2
                   Air Traffic Control: Status of FAA’s Modernization Program (GAO/RCED-95-175FS, May 26, 1995), Air
                  Traffic Control: Status of FAA’s Modernization Program (GAO/RCED-94-167FS, April 15, 1994), and Air
                  Traffic Control: Status of FAA’s Modernization Program (GAO/RCED-93-121FS, April 16, 1993).
                  3
                   High-Risk Series: An Overview (GAO/HR-95-1, February 1995).



                  Page 14                                                     GAO/AIMD-97-30 Air Traffic Control
                     Chapter 1
                     Introduction




                     The Congress will have provided FAA with approximately $23 billion of the
                     $34 billion through fiscal year 1997. The ATC systems portion alone,
                     excluding facility upgrades and support equipment, totals over $20 billion
                     of the planned $34 billion investment. The $20 billion will provide, in total,
                     about 170 new systems, but additional systems are being planned through
                     the year 2015. The modernization is still far from complete as nearly
                     $6 billion of the $20 billion still remains to be spent after 1997 on portions
                     of 73 systems.


ATC Facilities       Automated information processing and display, communication,
                     navigation, surveillance, and weather resources permit air traffic
                     controllers to view key information, such as aircraft location, aircraft flight
                     plans, and prevailing weather conditions, and to communicate with pilots.
                     These resources reside at, or are associated with, several ATC
                     facilities—the Air Traffic Control System Command Center (ATCSCC), flight
                     service stations, air traffic control towers, terminal radar approach control
                     (TRACON) facilities, and air route traffic control centers (en route centers).
                     These facilities’ ATC functions are described below.

                 •   The ATCSCC in Herndon, Virginia, coordinates operations between the en
                     route centers by combining traffic flow information from each. This
                     information allows the ATCSCC to provide a snapshot of the traffic flows
                     across the United States that is in turn used to ensure that airports do not
                     exceed capacities.
                 •   About 90 flight service stations provide pre-flight and in-flight services,
                     such as flight plan filing and weather report updates, primarily for general
                     aviation aircraft.
                 •   Airport towers control aircraft on the ground, before landing, and after
                     take-off when they are within about 5 nautical miles of the airport, and up
                     to 3,000 feet above the airport. Air traffic controllers rely on a combination
                     of technology and visual surveillance to direct aircraft departures and
                     approaches, maintain safe distances between aircraft, and communicate
                     weather-related information, clearances, and other instructions to pilots
                     and other personnel.
                 •   Approximately 180 TRACONs sequence and separate aircraft as they
                     approach and leave busy airports, beginning about 5 nautical miles and
                     ending about 50 nautical miles from the airport, and generally up to 10,000
                     feet above the ground, where en route centers’ control begins.
                 •   Twenty en route centers control planes over the continental United States
                     in transit and during approaches to some airports. Each en route center
                     handles a different region of airspace, passing control from one to another



                     Page 15                                        GAO/AIMD-97-30 Air Traffic Control
    Chapter 1
    Introduction




    as respective borders are reached until the aircraft reaches TRACON
    airspace. Most of the en route centers’ controlled airspace extends above
    18,000 feet for commercial aircraft. En route centers also handle lower
    altitudes when dealing directly with a tower, or when agreed upon with a
    TRACON.
•   Two en route centers—Oakland and New York—also control aircraft over
    the ocean. Controlling aircraft over oceans is radically different from
    controlling aircraft over land because radar surveillance only extends 175
    to 225 miles offshore. Beyond the radars’ sight, controllers must rely on
    periodic radio communications through a third party—Aeronautical Radio
    Incorporated (ARINC), a private organization funded by the airlines and FAA
    to operate radio stations—to determine aircraft locations. See figure 1.1
    for a visual summary of the ATC facilities that control aircraft.




    Page 16                                      GAO/AIMD-97-30 Air Traffic Control
Chapter 1
Introduction




Page 17        GAO/AIMD-97-30 Air Traffic Control
                                             Chapter 1
                                             Introduction




Figure 1.1: ATC Facilities That Control Aircraft




                                                                TRACON




                                                            Airport Tower




                                             Page 18                        GAO/AIMD-97-30 Air Traffic Control
                           Chapter 1
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En Route Center




Flight Service Station   ATCSCC




                           Page 19        GAO/AIMD-97-30 Air Traffic Control
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ATC Infrastructure Is An   The ability of FAA’s systems to interoperate, both within and across
Enormous and Complex       facilities, as one integrated system of systems is essential to ATC
System of Systems          operations.4 Each of the five facilities highlighted above contain numerous
                           interrelated systems. For example, the en route centers alone rely on over
                           50 systems to perform mission-critical information processing and display,
                           navigation, surveillance, communications, and weather functions.
                           Examples include the systems that display aircraft situation data for air
                           traffic controllers, the system that collects and displays data from various
                           weather sources, radars for aircraft surveillance, radars for wind and
                           precipitation detection, ground-to-ground and ground-to-air
                           communications systems, and systems to back-up primary systems.

                           In addition, systems from different facilities also interact with each other
                           so that together they can successfully execute the total ATC process. For
                           example, controllers’ displays currently integrate data on aircraft position
                           from surveillance radars with data on flight destination from flight
                           planning data systems. The ability of these systems to interoperate and
                           continually exchange data in real-time is safety critical. Figure 1.2 depicts
                           the five key air traffic control facilities (left section), the interaction
                           between systems both within and between facilities (middle section), and
                           the complexity of the systems associated with just one type of
                           facility—the en route centers (right section—these systems are described
                           in appendix I).




                           4
                            Interoperability is the ability of disparate systems to work together efficiently and effectively over a
                           network.



                           Page 20                                                          GAO/AIMD-97-30 Air Traffic Control
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Page 21        GAO/AIMD-97-30 Air Traffic Control
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Figure 1.2: ATC Infrastructure Is a Complex System of Systems




                                         Page 22                GAO/AIMD-97-30 Air Traffic Control
                                     Chapter 1
                                     Introduction




                   ARSR-3/4                            ATCBI-4/5                                    RMSs
              Primary Surveillance               Secondary Surveillance                          Surveillance
                                                                                 LCU              Navigation        RCL/LDRCL/
                                                                                                                    LINCS/Telco      RCAG
                                                        ARSR-1/2                                   Weather
                               CD-2 Digital        Primary Surveillance                           Automation                          RCE/
                                                                                                Communication                        DSRCE

                                        MODE-S                GMCC                  ATCT/LCU          Voice     Data                          BUEC
                                                               WS                     AFSS                                                     Site
                                                                                                                       External


TRACON/
ARTS
                                                                                                                                       RCE/
ATCT/                                                                                     AMCC             RCOM                       DSRCE
                               PAMRI                                 MPS
TDLS                                                                                       WS            (NARACS)
                                                      Users                                                                           MVR/
FAATC/
                                                                                                                                      DVRS
IFCN

ATCT/FDIO                                                           MDT                                                         VSCS
TRACON/       FDIO/                                                                                                          Comm. Switch
FDIO         CCU/RCU

NAWPF/                                              EDARC
               PSN                                                                                                     DMN
PSN                                                                               CDC                                               BUEC
                       Users                                                                                                       Back-up
                                                Host Computer               DCC/DCCR/DG
                                                   System                   Display Controls                                      A/G Comm.
NAWPF/
AWP
                           FSDPS
AFSS/
AFSSWS
                                                                           CRD               PVD
NAWPF/
              ADAS
WMSCR
                                                                                                                     DOTS          ODAPS

NAWPF/
WMSCR
                                                                          LAN
                                                         MWP                                                  PVD                       TMS
                                          PUP                                                                                           LAN
                                                                                Briefing Terminals
                                                                                                                         ASD



                                           NEXRAD                     NAWPF/                Weather
            AWOS/          DUATS                                                                                                  VNTSC/ETMS Hub
            ASOS           Vendor        Weather Radar                WMSCR                 Vendor


                                                                          En Route Center

                                                                          Oceanic

                                                                          TMU




                                     Page 23                                                                    GAO/AIMD-97-30 Air Traffic Control
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                             Introduction




Past Modernization Efforts   Over the past 15 years, FAA’s modernization program has experienced
Have Been Plagued by         substantial cost overruns, lengthy schedule delays, and significant
Problems                     performance shortfalls. To illustrate, the long-time centerpiece of this
                             modernization program—the Advanced Automation System (AAS)—was
                             restructured in 1994 after estimated costs tripled from $2.5 billion to
                             $7.6 billion and delays in putting significantly less-than-promised system
                             capabilities into operation were expected to run 8 years or more. Similarly,
                             increases in costs for three other ATC projects5 have ranged from 51 to
                             511 percent, and schedule delays have averaged almost 4 years. For
                             example, the per-unit cost estimate for the Voice Switching and Control
                             System increased 511 percent, and the first site implementation was
                             delayed 6 years from the original estimate.

                             Shortfalls in performance have affected AAS, as well as other projects. For
                             example, the critical Initial Sector Suite System component of AAS, which
                             was intended to replace controllers’ workstations at en route centers,
                             faced so many technical problems that it was severely scaled back. In
                             addition, difficulties in developing the Air Route Surveillance Radar-4
                             software and integrating it with other ATC systems delayed its
                             implementation for years.

                             GAO’s work over the years has highlighted weaknesses in FAA’s
                             management of the modernization that have caused cost, schedule, and
                             performance problems. First, FAA did not historically manage its
                             acquisition of major systems in accordance with Office of Management
                             and Budget Circular A-1096 and its own acquisition policies. For example,
                             FAA did not analyze its mission needs, did not adequately specify ATC
                             systems requirements, and performed flawed or limited analyses of
                             alternatives for achieving those needs. This is contrary to our finding that
                             successful public and private organizations tie decisions on information
                             technology investments to explicit and quantifiable mission
                             improvements.7 Second, some systems did not meet agency specifications.
                             Finally, FAA has provided inadequate oversight of contractor performance.
                             Additionally, GAO recently reported that FAA’s organizational culture has
                             been an underlying cause of the agency’s acquisition problems,


                             5
                             The three projects and their respective percentage change in unit costs are the Voice Switching and
                             Control System (511 percent), the Integrated Terminal Weather System (129 percent), and the Aviation
                             Weather Observing System (51 percent).
                             6
                               Major Systems Acquisition, Executive Office of the President, Office of Management and Budget
                             (April 5, 1976).
                             7
                              Executive Guide: Improving Mission Performance Through Strategic Information Management and
                             Technology (GAO/AIMD-94-115, May 1994).



                             Page 24                                                      GAO/AIMD-97-30 Air Traffic Control
                          Chapter 1
                          Introduction




                          encouraging employee behavior that did not reflect a strong commitment
                          to mission focus, accountability, coordination, and adaptability.8


ATC Modernization Will    Because of the past problems with FAA modernization efforts, the Congress
Proceed Under New         enacted legislation in October 1995 that directed FAA to design and
Acquisition Management    implement a new acquisition management system.9 The Act directed the
                          FAA to develop and implement an acquisition system that would address
System                    the unique needs of the agency. At a minimum, the system was to provide
                          for more timely and cost-effective acquisitions. To help achieve this goal,
                          the Act exempted FAA from most federal procurement and personnel laws
                          and regulations. On April 1, 1996, in response to the act, the FAA
                          Administrator began implementation of FAA’s new system.

                          The new acquisition management system is intended to improve
                          coordination and mission focus by strengthening the “front-end” of the
                          acquisition process. Specifically, the developers and operators are
                          expected to work together to analyze mission needs and alternatives
                          before senior management makes capital investment decisions and assigns
                          projects to development teams.


FAA Organizations         Two major FAA organizations play key roles in the development and
Responsible for Systems   evolution of ATC systems—the Office of the Associate Administrator for
Development and           Research and Acquisitions (ARA) and the Office of the Associate
                          Administrator for Air Traffic Services (ATS). Briefly, ARA is responsible for
Maintenance               developing and fielding ATC systems, while ATS is responsible for operating,
                          maintaining, and enhancing ATC systems. Cross-functional integrated
                          product teams (IPT) residing in ARA are responsible for ATC systems
                          development.

                          ARA manages the research, development, and acquisition of modernization
                          projects. According to the Associate Administrator for ARA, only one-half
                          of the total systems development budget is spent by ARA, while the other
                          one-half is spent by ATS implementing system enhancements. Within ARA,
                          two groups are responsible for acquiring systems, while the others handle
                          cross-cutting management functions (e.g., budget formulation and
                          program evaluation). These two groups are the Office of Systems


                          8
                           Aviation Acquisition: A Comprehensive Strategy Is Needed for Cultural Change at FAA
                          (GAO/RCED-96-159, August 22, 1996).
                          9
                           Department of Transportation and Related Agencies Appropriations Act 1996, P. L. No. 104-50, sec.
                          348, 109 Stat. 436, 460 (1995).



                          Page 25                                                      GAO/AIMD-97-30 Air Traffic Control
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Development (AUA) and the Office of Communication, Navigation, and
Surveillance Systems (AND).

Five IPTs reside in AUA and are organized by ATC business areas (i.e., en
route, terminal, weather and flight service, air traffic management,
oceanic). Five IPTs reside in AND and are organized by ATC functional areas
(i.e., infrastructure, communications, surveillance, GPS/navigation,
aircraft/avionics). IPTs are responsible for research, development, and
acquisition as well as for ensuring that new equipment is delivered,
installed, and working properly. For example, the en route IPT comprises
product teams for the Display Channel Complex Rehost, the Display
System Replacement, the Voice Switching and Control System, and several
other en route systems. Each IPT includes systems and specialty engineers,
logistics personnel, testing personnel, contract personnel, and lawyers as
well as representatives from the organizations responsible for operating
and maintaining the ATC equipment.

The second major organization involved with ATC systems is ATS. ATS is
responsible for directing, coordinating, controlling, and ensuring the safe
and efficient utilization of the national airspace system. Organizations
within ATS are responsible for planning, operating, maintaining, and
enhancing ATC systems. Responsibility for managing projects is transferred
from ARA to ATS once a system has been installed and is operational.

The FAA Technical Center is the ATC system test and evaluation facility and
supports ATC systems’ research, engineering, and development. See figure
1.3 for a visual summary of the ATC modernization management structure.




Page 26                                       GAO/AIMD-97-30 Air Traffic Control
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Page 27        GAO/AIMD-97-30 Air Traffic Control
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                                                                           Introduction




Figure 1.3: ATC Modernization and Maintenance Organizational Chart


                                                                                             Administrator
                                                                                                AOA

                                                                Assistant
                                                              Administrator            Deputy Administrator
                                                            for System Safety                 ADA
                                                                   ASY

                                           Assistant                         Assistant                                  Assistant                            Assistant
  Chief Counsel                                                            Administrator                                                                 Administrator for
                                         Administrator                                                                Administrator
      AGC                                                              for Government and                                                               Policy, Planning and
                                        for Civil Rights                                                            for Public Affairs
                                                                          Industry Affairs                                                             International Aviation
                                             ACR                               AGI                                        APA                                    API

                                                                                                                                            Office of Aviation        Europe, Africa and
                                                                                                                                            Policy and Plans          Middle East Office
                                                                                                                                                  APO                       AEU

                                                                                                                                         Office of Environment           Asia-Pacific
                                                                                                                                              and Energy                    Office
                                                                                                                                                  AEE                       APC

                                                                                                                                               Office of                Latin America-
                                                                                                                                         International Aviation        Caribbean Office
                                                                                                                                                  AIA                        ALC

                                                                Associate                Associate
        Associate                  Associate                                           Administrator                                                                    Associate
      Administrator                                           Administrator                                                                                        Administrator for
                                 Administrator                                      for Regulation and
    for Administration                                      for Civil Aviation                                                                                     Air Traffic Services
                                  for Airports                                          Certification
          AAD                                                    Security                                                                                                 ATSa
                                      ARP                                                  AVR
                                                                  ACS


     Office of Business              Office of Airport        Office of Civil                                                                                        Airway Facilities       Office of System
                                                                                     Office of Accident       Air Traffic System
       Information &                  Planning and           Aviation Security                                                           Air Traffic Service
                                                                                       Investigation         Requirements Service                                        Service                 Capacity
        Consultation                  Programming              Intelligence                                                                     AAT
                                                                                            AAI                      ARS                                                  AAF                      ASC
            ABC                            APP                      ACI
                                     Office of Airport        Office of Civil             Aircraft                                              Air Traffic                NAS                Airport Capacity
     Office of Financial                                                                                         Airway Facilities
                                        Safety and           Aviation Security           Certification                                          Resource                 Operations               Planning
          Services                                                                                                Requirements
                                        Standards               Operations                Service                                              Management                  AOP                    ASC-100
            ABA                                                                                                       AFR
                                           AAS                     ACO                       AIR                                                   ATX
      Office of Human                                          Office of Civil           Office of                 Air Traffic                 Air Traffic               Operational             Airspace
          Resource                                           Aviation Security                                    Requirements
                                                                                     Aviation Medicine                                         Operations                 Support             Capacity Planning
       Management                                           Policy and Planning                                       ATR
                                                                                            AAM                                                   ATO                      AOS                   ASC-200
            AHR                                                     ACP

                                                                                      Flight Standards                                      Air Traffic Airspace       NAS Transition
                                                                                                                                               Management                   and
                                                                                           Service
                                                                                                                                                    ATA                Implementation
                                                                                             AFS                                                                            ANS

                                                                                         Office of                                                                     Spectrum Policy
                                                                                        Rulemaking                                            Field Divisions         and Management
                                                                                           ARM                                                                              ASR


                                                                                                                                                                         Resources
                                                                                                                                                                        Management
                                                                                                                                                                           AFZ

                                                                                                                                                                      Aviation System
                                                                                                                                                                         Standards
                                                                                                                                                                            AVN


                                                                                                                                                                       Field Divisions




                           Central                                                                           Northwest                                                                     Mike Monroney
    Alaskan                                       Eastern         Great Lakes       New England                                  Southern             Southwest        Western-Pacific
                           Region                                                                            Mountain                                                                       Aeronautical
    Region                                        Region            Region            Region                                      Region               Region             Region
                            ACE                                                                               Region                                                                           Center
      AAL                                          AEA               AGL               ANE                                         ASO                  ASW                AWP
                                                                                                               ANM                                                                              AMC




                                                                           Page 28                                                                                  GAO/AIMD-97-30 Air Traffic Control
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                                                                                                          Associate
                                                                                                        Administrator
                                                                                                      for Research and
                                                                                                        Acquisitions
                                                                                                            ARA


Office of Independent                            Office of Air Traffic       Office of Aviation            Office of                                  Office of System      William J. Hughes
                        Office of Acquisitions                                                                              Office of Information
  Operational Test                                     Systems                   Research             Comm., Navigation,                              Architecture and
                                 ASU                                                                                             Technology                                   Tech Center
    and Evaluation                                  Development                    AAR                 and Surveillance                             Investment Analysis
         ATQ                                             AUA                                            Systems, AND              AIT (CIO)                 ASD                    ACT

                                                                                Chief Scientist        Integrated Product        Corporate                Architecture           Resource
                           Acquisition Policy
                                                   Integrated Product         for Human Factors             Team for            Information               and System            Management
                            and Procedures
                                                   Team for En Route               Division               Infrastructure      Management Div.             Engineering             Division
                               Division
                                                        AUA-200                    AAR-100                  AND-100               AIT-100                  ASD-100               ACT-100
                               ASU-100
                                                                                                       Integrated Product     Integrated Product        Evaluation and
                                                                                  Research                  Team for                                     Configuration        ATC Engineering
                           Quality Assurance       Integrated Product                                                              Team for
                                                                                   Division             Communications                                   Management           and Test Division
                                Division           Team for Terminal                                                         Information Systems
                                                                                  AAR-200                   AND-300                                       ASD-200                 ACT-200
                               ASU-200                  AUA-300                                                                    AIT-200
                                                   Integrated Product            Research and          Integrated Product     Integrated Product       NAS Programming        CNS Engineering
                               Contracts           Team for Weather               Acquisitions              Team for              Team for IT            and Financial
                                Division                                                                                                                                      and Test Division
                                                   and Flight Service        International Division        Surveillance            Services              Management              ACT-300
                               ASU-300                                             AAR-300                  AND-400                 AIT-300                ASD-300
                                                   Systems, AUA-400
                                                                              Airport and Aircraft     Integrated Product     Integrated Product      Investment Analysis        Facilities
                                                   Integrated Product
                                                                              Safety, Research           Team for GPS/            Team for IT           and Operations          Management
                                                   Team for Air Traffic
                                                                              and Development              Navigation             Acquisitions             Research               Division
                                                      Management
                                                                              Division, AAR-400             AND-500                AIT-400                 ASD-400               ACT-400
                                                        AUA-500
                                                                              Aviation Security        Integrated Product                                                    Aviation Simulation
                                                   Integrated Product           Research and                Team for                                                             and Human
                                                    Team for Oceanic            Development             Aircraft/Avionics                                                     Factors Division
                                                        AUA-600               Division, AAR-500             AND-600                                                               ACT-500
                                                                                                                                                                             Airport Management
                                                                                                                                                                               and Emergency
                                                                                                                                                                             Operations Division
                                                                                                                                                                                   ACT-600


                                                                   a
                                                                       ATS is currently being reorganized.




                                                                   Page 29                                                                           GAO/AIMD-97-30 Air Traffic Control
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                         Introduction




                         The objectives of our review were to determine (1) whether FAA has a
Objectives, Scope,       target architecture(s), and associated subarchitectures, to guide the
and Methodology          development and evolution of its ATC systems, and (2) what, if any,
                         architectural incompatibilities exist among systems and what is the effect
                         of these architectural incompatibilities.

                         To determine whether FAA has a target architecture(s), and associated
                         subarchitectures, to guide the development and evolution of its ATC
                         systems, we

                     •   researched current literature and interviewed systems architecture
                         experts to identify the key components of a complete systems
                         architecture;
                     •   analyzed FAA’s National Airspace System Architecture (versions 1.5 and
                         2.0) and interviewed officials responsible for developing this architecture
                         to determine whether the proposed systems architecture is complete and
                         comprehensive;
                     •   reviewed additional FAA efforts to develop systems architectures, including
                         the Corporate Systems Architecture;
                     •   interviewed the 10 IPTs responsible for ATC systems development to
                         determine how architectural considerations are incorporated in
                         development efforts;
                     •   reviewed the NAS System Requirements Specification (NAS-SR-1000), the NAS
                         Level 1 Design Document (NAS-DD-1000), and the NAS System Specification
                         (NAS-SS-1000) to determine whether existing guidance constitutes the
                         components of a systems architecture;
                     •   interviewed ARA organizations responsible for developing software,
                         communications, data management, and security guidance about existing
                         guidance and efforts to improve this guidance;
                     •   interviewed FAA’s Chief Information Officer (CIO) to determine what role
                         the CIO plays in the development of FAA’s systems architecture and whether
                         this role is consistent with recently passed legislation; and
                     •   analyzed FAA’s current structure and processes associated with
                         architectural development and enforcement.

                         To determine what, if any, architectural incompatibilities exist among
                         systems and what is the effect of these architectural incompatibilities, we

                     •   acquired and analyzed information on the hardware, operating systems,
                         application languages, database management, communications, and
                         security characteristics of seven existing and under development ATC
                         systems to identify architectural incompatibilities;



                         Page 30                                       GAO/AIMD-97-30 Air Traffic Control
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    Introduction




•   reviewed key technical documents associated with some of these systems,
    including interface control documents and technical briefings;
•   analyzed the cost, schedule, and performance impacts of the architectural
    incompatibilities that exist among ATC systems;
•   interviewed the Director of Operational Support to obtain ATC
    maintenance concerns and to obtain his opinion about system
    incompatibilities; and
•   identified the application languages used in 54 operational ATC systems.

    We performed our work at the Federal Aviation Administration in
    Washington D.C., and the FAA Technical Center in Atlantic City, New
    Jersey, from March 1996 through January 1997. Our work was performed
    in accordance with generally accepted government auditing standards.

    Department of Transportation (DOT) and FAA officials, including the FAA
    Deputy Director for Architecture and System Engineering, the FAA Chief
    Scientist for Software Engineering, and the FAA Chief Engineer for Air
    Traffic Systems Development, provided oral comments on a draft of this
    report. Their comments have been addressed in the Agency Comments
    and Our Evaluation sections at the end of chapters 3 and 4 and as
    appropriate in the body of the report.




    Page 31                                     GAO/AIMD-97-30 Air Traffic Control
Chapter 2

Systems Architecture Overview


                        Over the last decade, as computer-based systems have become larger and
                        more complex, the importance of and reliance on systems architectures
                        has grown steadily. These comprehensive “construction plans” or
                        “blueprints” systematically detail the full breadth and depth of an
                        organization’s mission-based modus operandi, first in logical terms, such
                        as defining business functions, providing high-level descriptions of
                        information systems and their interrelationships, and specifying
                        information flows; and second in technical terms, such as specifying
                        hardware, software, data, communications, security, and performance
                        characteristics. Without a systems architecture to guide and constrain a
                        modernization program, there is no systematic way to preclude
                        inconsistent system design and development decisions, and the resulting
                        suboptimal performance and added cost associated with these
                        incompatible systems. This is why leading public and private sector
                        organizations strongly endorse defining and enforcing systems
                        architectures as an integral and vital aspect of modernizing their
                        information systems.


                        We found that leading organizations in the private sector and in
Systems Architectures   government use systems architectures to guide mission-critical systems
Have Emerged as the     development and to ensure the appropriate integration of information
Centerpiece of System   systems through common standards.1 In addition, experts in academia
                        have also championed the systems architecture approach. For example,
Development             the Software Engineering Institute (SEI) at Carnegie Mellon University
Programs                includes the development and evolution of a systems architecture as a key
                        process area in its Systems Engineering Capability Maturity Model
                        (SE-CMM).2 The SE-CMM states that the systems architecture should detail
                        both logical and technical system elements, their relationships, interfaces,
                        and system requirements, and should guide the system design and
                        implementation.

                        Congress has also recognized the importance of systems architectures as a
                        means to improve the efficiency and effectiveness of federal information
                        systems by enacting the 1996 Clinger-Cohen Act. The act, among other
                        provisions, requires that department-level CIOs develop, maintain, and
                        facilitate integrated systems architectures.



                        1
                         Executive Guide: Improving Mission Performance Through Strategic Information Management and
                        Technology (GAO/AIMD-94-115, May 1994).
                        2
                          A Systems Engineering Capability Maturity ModelSM, Version 1.1, Carnegie Mellon University,
                        Software Engineering Institute, (SECMM-95-01, CMU/SEI-95-MM-003, November 1995).



                        Page 32                                                       GAO/AIMD-97-30 Air Traffic Control
                         Chapter 2
                         Systems Architecture Overview




                         Reflecting the general consensus in the industry that large, complex
Overview of a            systems development efforts should be guided by explicit architectures, in
Systems                  1992, GAO issued a report defining a comprehensive framework for
Architecture’s Content   designing and developing systems architectures.3 This framework divides
                         systems architectures into two principal components—a logical
                         component and a technical component. The logical component is essential
                         to ensure that an agency’s information systems support accomplishing a
                         specific mission(s), while the technical component provides the detailed
                         guidance needed to develop and evolve these systems.

                         At the logical level, the architecture includes a high-level description of the
                         organization’s mission, functional requirements, information requirements,
                         systems, information flows among systems, and interfaces between
                         systems. The logical architecture is derived from a strategic information
                         systems planning process that clearly defines the organization’s current
                         and future missions and concepts of operations. It then defines the
                         business functions required to carry out the mission and the information
                         needed to perform the functions. Finally, it describes the systems that
                         produce the information. An essential element of the logical architecture is
                         the definition of the component interdependencies (i.e., information flows,
                         system interfaces). Once the logical architecture is defined, an
                         organization knows its portfolio of desired systems and has a clear
                         understanding of how these systems will collectively carry out the
                         organization’s objectives. The purpose of the logical architecture is to
                         ensure that the systems meet the business needs of the organization.

                         The technical level details specific information technology and
                         communications standards and approaches that will be used to build
                         systems, including those that address critical hardware, software,
                         communications, data management, security, and performance
                         characteristics. The purpose of the technical architecture is to ensure that
                         systems are interoperable, function together efficiently, and are
                         cost-effective over their life cycles (i.e., including maintenance costs).
                         Figure 2.1 displays the key logical and technical components of a systems
                         architecture.




                         3
                          Strategic Information Planning: Framework for Designing and Developing System Architectures
                         (GAO/IMTEC-92-51, June 1992).



                         Page 33                                                    GAO/AIMD-97-30 Air Traffic Control
                                             Chapter 2
                                             Systems Architecture Overview




Figure 2.1: Key Logical and Technical Components of a Systems Architecture



                                                                     Agency Mission

                                                               Concept of Operations

                                                                         Functions
    Logical
                                                                    Information Flows
                          System A                System B                System C                System D                System X

                                                                    System Interfaces

                                                      Hardware Characteristics and Standards
                                            (e.g., expandability, reliability, maintainability, fault tolerance)
                                                          Software Characteristics and Standards
                         (e.g., reliability, testability, flexibility, maintainability, portability, reusability, adherence to open
                        systems standards, standards for the languages to be used, institutionalized process standards
                               or methodologies for designing, coding, testing, and documenting software projects)

                                                   Communications Characteristics and Standards
                                        (e.g., reliability, availability, standards for communications protocols)
  Technical
                                                         Data Characteristics and Standards
                                   (e.g., standards for data formats and naming conventions, a data dictionary)

                                                      Security Characteristics and Standards
                             (e.g., hardware and software solutions to address security requirements that are based
                                               on a security policy and security concept of operations)

                                                     Performance Characteristics and Standards
                       (e.g., ability to meet operational requirements, response-time requirements, availability, reliability)




                                             Page 34                                                    GAO/AIMD-97-30 Air Traffic Control
Chapter 3

Lack of a Complete ATC Systems
Architecture Impacts ATC Modernization’s
Cost and Performance
                           FAA lacks a complete systems architecture to guide the development and
                           evolution of its ATC systems modernization. While FAA has made good
                           progress over the last 2 years in defining a logical ATC systems
                           architecture, FAA has not adequately addressed its need for a technical ATC
                           systems architecture.

                           The lack of an ATC systemwide technical architecture has caused, and will
                           continue to cause, incompatibilities among the ATC systems, such as
                           differences in communications protocols1 and application languages, that
                           require additional development, integration, and maintenance resources to
                           overcome. The incompatibilities also make it difficult to share application
                           software among systems and to migrate to vendor-independent2 operating
                           environments, thereby effectively foreclosing two opportunities to reduce
                           system development and maintenance costs.


                           FAA  is currently defining a logical ATC systems architecture that describes
FAA Is Making Good         FAA’s  concept of operations, business functions, high-level descriptions of
Progress in Defining a     information systems and their interrelationships, and information flows
Logical ATC Systems        among systems. This high-level systems blueprint provides a roadmap that
                           is to guide ATC systems over the next 20 years.
Architecture
FAA’s National Airspace    FAA  is defining a comprehensive and evolutionary logical ATC systems
System Architecture        architecture in its National Airspace System (NAS) architecture. Among
Includes a Broad-Based     other things, the architecture provides a description of the future aviation,
                           air traffic management, and air navigation system in terms of services,
and Evolutionary Logical   functions, and ATC systems. Specifically, it describes FAA’s concepts of
ATC Architecture           operations, requirements in terms of the business functions to be
                           performed, associated systems to be used, the relationships between these
                           functions and systems, the information needed to perform these functions,
                           and the flow of information among the functions and systems. In addition,
                           it provides a roadmap for evolving the ATC systems through the year 2015.

                           The goals of the logical architecture are to (1) provide the aviation
                           community with a cohesive and collaborative means to influence the NAS
                           evolution, (2) provide a foundation for FAA acquisition decisions, and
                           (3) provide the aviation community with insight into the timing of major


                           1
                            Sets of rules that govern communications among computer systems.
                           2
                            A vendor-independent environment uses hardware and software with characteristics that conform to
                           specifications in the public domain (that is, that are not unique to a particular vendor or group of
                           vendors).



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                           changes to NAS. According to FAA, the NAS architecture is intended to
                           eliminate “stovepiped” development by defining an evolution towards
                           target architectures that represent coordinated and integrated operational
                           concepts and a comprehensive system of systems view. The NAS
                           architecture is not intended to provide the details needed to actually
                           design and build these systems (i.e., details that would be provided by the
                           technical architecture).

                           FAA issued version 2.0 of the NAS architecture in October 1996 and
                           subsequently released it for industry and government comment. The first
                           complete version of the architecture is scheduled to be completed in
                           December 1997.


Summary of the NAS         The NAS architecture is divided into five key parts—concepts of
Architecture’s Five        operations, service and functional requirements, systems and programs,
Principal Components       roadmap, and issues. Each is briefly discussed below.3

                       •   Concepts of Operations: This section describes an evolving series of
                           concepts of operations through the year 2015 and emphasizes the
                           migration to a free-flight environment. The current concept of operations
                           relies on analog voice communications between controllers and pilots, and
                           ground-based radar surveillance to control aircraft. A free-flight
                           environment is one in which the pilots are free to select their own routes
                           and speed in real time. In this environment, air traffic restrictions would
                           be imposed only to ensure minimum aircraft separation, preclude
                           exceeding airport capacity, prevent unauthorized flight through
                           special-use airspace, and ensure safety. A free-flight environment relies
                           less on voice communications and ground-based radar systems and more
                           on aircraft position displays in the cockpit and satellite surveillance and
                           navigation technologies, such as the Global Positioning System (GPS). The
                           transition from the current to the free-flight concept of operations will be
                           evolutionary. Mid-term concepts of operations will define FAA’s evolution
                           methodically and gradually to a free-flight environment.
                       •   Service and Functional Requirements: This section describes services and
                           associated functional requirements that are required to carry out the
                           concepts of operations. The service requirements include air traffic (i.e.,
                           flight planning, flight support, aircraft navigation and guidance, traffic
                           management, separation, data information management, and
                           communication management), airport, security, safety, certification,

                           3
                            This summary is based on version 1.5 of the NAS Architecture, which was issued in March 1996.
                           Version 2.0 descriptions of these five parts are consistent with this summary.



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    infrastructure, and administrative and acquisition support services. These
    service requirements are further broken down by functional requirements
    (e.g., provide forecasted weather information, provide air traffic flow
    information) and specify existing systems and describe future NAS systems
    (e.g., Host Computer System and Display System Replacement,
    respectively).
•   Systems and Programs: This section describes the systems associated with
    each functional area (i.e., communications, weather, automation,
    surveillance, maintenance and support, navigation) and business area (i.e.,
    en route, terminal, tower, oceanic, air traffic management) of the proposed
    architecture. For each of the functional areas the following information is
    provided: (1) listing of systems through the year 2015, (2) current
    programs and schedules from the Capital Investment Plan (CIP) and the
    Research, Engineering, and Development (RE&D) plan, and (3) transition
    strategy and diagrams.4 In addition, this section provides systems
    drawings (i.e., high-level wiring diagrams) of the various business areas for
    the 1995 and 2005 time frames. Appendix I provides a simplified block
    diagram for the near- and mid-term en route business area’s systems
    environment, which is very complex (i.e., includes many systems that
    interact in many ways).
•   Roadmap: This section provides a transition plan for replacing systems,
    replacing existing infrastructure, and introducing new capabilities. The NAS
    architecture roadmap presents a proposed architecture in several
    functional areas (e.g., navigation, surveillance) and describes a transition
    strategy to migrate from the current systems environment to the proposed
    architecture. For example, for the navigation functional area, it describes a
    gradual transition strategy to a satellite-based navigation system.
    Specifically, it describes the deployment schedule for the primary system,
    Wide Area Augmentation System (WAAS), the schedule for
    decommissioning existing systems, and the additional system deployment
    schedules to support the far-term concept of operations. The roadmap
    describes the changes in ATC systems through time as they evolve to
    support free-flight.
•   Issues: This section provides a collection of papers on outstanding issues
    whose resolutions should have the greatest potential impacts on the future
    of ATC systems. These issues are the “forks in the road” where a decision is
    needed to define a particular roadmap to the future. For example, one
    paper presents a series of unanswered questions on performance and
    backup requirements for future ATC surveillance. Another recommends the



    4
     The CIP and RE&D plans provide lists of ongoing and future projects scheduled for development and
    research respectively. Both are updated annually.



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need for a free-flight action plan that is to guide FAA’s transition to a
free-flight environment.

The interrelationships among the NAS architecture’s services, functional
areas, and associated systems are quite complex, as any one system may
support multiple functional and service areas. For example, the Host
Computer System (HCS) is an automation system located in the en route
facilities that supports several business areas ( i.e., the en route business
area by processing data from many different radar systems and air traffic
management (ATM) business area by providing flight track data to select
ATM systems). Figure 3.1 shows the relationships between the NAS
architecture air traffic services, business areas, functional areas, and
related systems.




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Figure 3.1: NAS Architecture Air Traffic Services, Business Areas, Functional Areas, and Related Systems




         Air Traffic
         Operations                                    ing
                                               nn
         Services                          Pla
                                g     ht                            port                    nc
                                                                                                 e
                            Fli                               S  up                  uid
                                                                                         a
                                                        ght                        dG
                                                    Fli                    na
                                                                              n
                                                                                                 ent
                                                                                                                                         Separation
                                                                      a tio                  m
                                                              a   vig                    age
                                                            tN                     a    n
                                                     af                         cM
                                                 rcr
                                                                                                                                              Other
                                               Ai                           f fi                  at   ion                                    Automation
                                                                        Tra                   par                                             Systems
                                                                                            Se
                                                                                                                                     En
                            To                                                                                                       Route
                                 we
                                      r                                                                                                       Host
                                                                                                                                              Computer
                                                                                                                                              System

                           Te
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                                  Oc
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               Ai                               ic
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                     raf                                                                                                   Communications
                         fic
                                Ma
                                      nag                                                                             Weather
                                               em
                                                     ent                                                     Automation
             Air Traffic
             Business                                                                                  Surveillance
             Areas                                                                                                                   Air Traffic
                                                                                             Navigation
                                                                                                                                     Functions
                                                                                   Mission Support & Facilities




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                            FAA’s  efforts to develop and evolve its “system of ATC systems” is not
FAA Has No Technical        guided and constrained by an ATC-wide technical architecture, and FAA
Systems Architecture        does not have an effective strategy for developing one. In 1995, FAA
                            recognized the importance of such an architecture by including the
                            development of an FAA corporate architecture in its 1996 Capital
                            Investment Plan. However, FAA decided to drop this effort from FAA’s 1997
                            plan in favor of other investment priorities. As a result, the IPTs have been
                            left to proceed individually in setting architectural standards and
                            developing and evolving systems. This has resulted in three IPTs
                            cooperatively developing similar but not identical architectures for their
                            respective areas, while others are proceeding without one. At the same
                            time, still other FAA organizations are independently attempting to develop
                            pieces (e.g., software guidance, security guidance) of a technical
                            architecture, but these efforts are not coordinated and neither individually
                            nor collectively constitute a complete ATC-wide technical architecture.
                            Without an ATC-wide technical architecture, FAA’s ATC systems have and
                            will continue to suffer from costly and inefficient incompatibilities.


Past Effort to Develop a    The concept of a technical systems architecture is not new to FAA. In FAA’s
Technical Systems           January 1996 Capital Investment Plan, FAA planned to develop a technical
Architecture Was            architecture, called the corporate systems architecture (CSA). According to
                            FAA plans, the CSA was to be a blueprint for achieving an open systems
Abandoned                   environment5 and was to be used to “guide, coordinate, and integrate the
                            acquisition, development and implementation of automated data
                            processing equipment, telecommunications, automated information
                            systems and data bases, and associated support services” across FAA.
                            However, the CSA effort was abandoned in favor of other funding priorities.
                            FAA’s CIO, who was tasked to develop the CSA, told us that the CSA was not
                            funded in 1996 because its sponsors and developers could not convince
                            FAA top management of its importance in providing benefits like cheaper
                            development, integration, and maintenance costs, and better systems
                            performance.


IPT Architectural Efforts   In the absence of an overall ATC technical systems architecture, the IPTs are
Are Limited and Do Not      left to their own devices in formulating guidance to build systems. As a
Constitute an ATC-Wide      result, three IPTs have cooperatively developed similar but not identical
                            technical architectures. The other seven IPTs are developing ATC systems,
Technical Architecture      which include such major systems as the Standard Terminal Automation

                            5
                             An open systems environment is one that is based on vendor-independent, publicly available
                            standards. An open system environment supports portable and interoperable applications through
                            standard services, interfaces, data formats, and protocols.



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    Replacement System (STARS) and the Wide Area Augmentation System
    (WAAS), without a technical architecture. (See figure 3.2 for a summary of
    architectural guidance used by the 10 IPTs.)

    With respect to the latter seven, officials for one IPT could not cite any
    technical architectural guidance being used, while officials for another IPT
    cited the NAS architecture, and officials for the other five cited the NAS
    “1,000-series” documents.6 However, neither the NAS architecture nor the
    NAS “1,000 series” constitutes a technical architecture. The NAS architecture
    is a logical architecture that provides no technical details, and the NAS
    “1,000 series” documents are neither a logical nor technical architecture.
    In fact, the Deputy Director for the Office of System Architecture and
    Investment Analysis, stated that the NAS “1,000 series” documents are
    “shelfware” and not useful in guiding future systems development. In
    commenting on a draft of this report, Systems Architecture and
    Investment Analysis officials stated that they plan to issue a revision to the
    NAS “1,000 series” documents in October 1997.


    Each of the three IPTs using their own, cooperatively developed technical
    architectures are described below.

•   ATM IPT: This IPT was the first to develop a technical architecture, which is
    called the ATM Domain Environment Definition Document. It provides
    guidelines and standards for, among other things, operating systems,
    communication protocols, data management, security, coding, and testing.
    ATM officials stated that they created this document to facilitate system
    integration and ATM software application migration among the systems
    they are developing, which include the Traffic Management System (TMS)
    and the Center TRACON Automation System (CTAS).
•   En route IPT: This IPT’s architecture governs development of such systems
    as the Display System Replacement (DSR) and the Host Interface
    Device/Local Area Network (HID/LAN). The architecture contains a systems
    development model and a standards profile, including data interchange,
    communications, security, and programming language standards.
•   Infrastructure IPT: This IPT’s architecture is for its NAS Infrastructure
    Management System (NIMS), which is this IPT’s primary system. The NIMS
    architecture includes both logical and technical components. It includes a
    standards profile that contains the same general categories of standards as
    the ATM and en route technical architectures.

    6
     The NAS “1,000 series” documents include the NAS System Requirements Specification (NAS-SR-1000),
    the NAS Level 1 Design Document (NAS-DD-1000), and the NAS System Specification (NAS-SS-1000). These
    documents reflect the NAS requirements baseline, the NAS allocated baseline, and the NAS system
    design, respectively.



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While the three IPTs tried to achieve architectural compatibility, they have
not been fully successful. For example, all three architectures specify C
and C++ as acceptable programming languages, but the en route
architecture also specifies Ada as an acceptable language. Also, although
the ATM, en route, and infrastructure architectures all specify compliance
to the Structured Query Language (SQL)-92 to access data, the en route
architecture acknowledges that the SQL-92 standard will have to be
modified at times to meet FAA’s real-time, mission-critical requirements.
Currently, FAA has no plan for doing this consistently across all three
systems environments. Further, the ATM technical architecture specifies
the ethernet protocol and the en route architecture specifies the Fiber
Distributed Data Interface (FDDI) protocol. These two protocols are not
compatible. FAA officials told us that they are aware of inconsistencies and
that they plan to resolve them, but have not defined the plan, scheduled its
implementation, or allocated resources for the effort.




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Figure 3.2: Architecture Guidance
Used by the 10 IPTs to Guide Ongoing        Number of IPTs using the guidance
and Future Development                      5




                                            4




                                            3




                                            2




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                                       Architecture guidance used by IPTs


                                            a
                                              Four of these five IPTs mentioned additional guidance that will supplement the “1,000 series”
                                            documents. This additional guidance included the NAS architecture, international
                                            standards/agreements, interface requirements documents and standards referenced in system
                                            specifications, and FAA’s Strategic Plan, Capital Investment Plan, Communications System Plan,
                                            Telecommunications Strategic Plan, and system/interface/operational requirements documents.
                                            None of these, either collectively or individually, provide the technical systems architecture details
                                            that are necessary to guide ATC systems development.




Other ATC Modernization                     In addition to these IPT-specific technical architectures, three other ARA
Organizations Have Begun                    offices (i.e., Office of Systems Architecture and Investment Analysis,
to Develop Parts of                         Office of Information Technology, Acquisition Policy Branch) have
                                            initiated efforts that relate to, but neither individually nor collectively
Optional Technical                          constitute a complete technical architecture. These efforts have begun to
Systems Architectures                       address data management, security, and software process and product
                                            standards; however, they are limited in scope, are incomplete, and will not
                                            be mandated for use across all ATC systems. Each is discussed below.

                                       •    The Office of Systems Architecture and Investment Analysis is adding a
                                            draft section on data management to the logical architecture that



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                           describes the current state of data exchange between ATC systems.
                           However, this section does not define specific standards (e.g., standards
                           for data elements and naming conventions), and FAA officials have not
                           established milestones for doing so. This office is also planning to develop
                           guidance addressing how security controls (e.g., hardware and software
                           solutions) will be implemented to satisfy security requirements. However,
                           this effort has not been approved by FAA management, and therefore
                           remains unfunded. Also, this office has created a menu of architectural
                           standards (e.g., data management, data interchange, communication
                           protocol, application development, and security standards) to increase
                           IPTs’ awareness of what standards exist for the IPTs to use at their own
                           discretion.
                       •   The Office of Information Technology is initiating efforts to improve
                           software acquisition processes, has trained the IPTs on software process
                           improvement, and has established a Software Engineering Process Group
                           to champion process improvement activities. However, these initiatives do
                           not specify software product standards, such as standard programming
                           languages and development tools, or standards for software structure,
                           both of which are critical to modernizing ATC systems cost effectively.
                           Moreover, FAA cannot yet demonstrate specific and measurable process
                           improvements.
                       •   The Acquisition Policy Branch has begun an initiative to develop systems
                           engineering guidance for IPTs’ optional use. Because this guidance is early
                           in its development and a complete draft does not yet exist, FAA would not
                           provide us a copy for review.


                           The lack of a complete systems architecture has produced architectural
Lack of a Technical        differences and incompatibilities among ATC systems, such as different
Systems Architecture       communication protocols and proprietary operating environments, and
Means Costly System        will continue to do so for future systems. (Examples of these differences
                           for key systems in the current and near-term en route environment are
Incompatibilities          provided in appendix II.) Further, the significance of these
                           incompatibilities will increase as FAA moves to a more networked systems
                           environment. Overcoming these incompatibilities means “higher than need
                           be” system development, integration, and maintenance costs, and reduced
                           overall systems performance. Additionally, because many existing systems
                           are largely proprietary, opportunities for application software reuse
                           among systems is effectively precluded and options for migrating
                           applications to new hardware and software platforms are restricted.




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Heterogenous               A system interface is hardware and software that acts as an interpreter to
Communications Protocols   interconnect different systems and allow for the exchange of data. The
and Data Formats Require   more similar the communications and data features of the systems that are
                           to communicate, the less complicated this interface. Conversely, the more
Expensive System           disparate the systems, the more complicated the interface.
Interfaces                 Communications and data management subarchitectures are essential to
                           standardize communication protocols and data formats, respectively, so
                           that system interfaces are less costly and easier to implement.

                           As described in chapter 1, system interoperability in the ATC system of
                           systems is essential for FAA to successfully perform its mission. However,
                           fundamental differences in how the systems communicate have made
                           exchanging data between systems more difficult and expensive because it
                           requires the development and maintenance of costly interfaces to
                           interconnect systems. This can be seen in the en route business area,
                           where a system known as the Peripheral Adapter Module Replacement
                           Item (PAMRI) operates as a collection of systems interfaces. Specifically,
                           PAMRI’s primary function is to convert differing protocols from feeder
                           systems, like aircraft surveillance radars and weather detection systems,
                           so that data from these systems can be used by the Host Computer System
                           (HCS), the centerpiece information processing system in the en route
                           centers.7 To perform this function, FAA spent over $38 million8 to develop
                           PAMRI and it spends millions9 annually to maintain it.


                           In addition to protocol conversion, PAMRI also performs data conversion of
                           its disparate feeder systems. This conversion is necessary to remedy the
                           data inconsistencies among ATC systems that feed HCS. These data
                           inconsistencies extend beyond just those systems that interface with HCS.
                           For example, FAA has hired a contractor to write an interface so that the
                           Center TRACON Automation System (CTAS) can talk to the Automated Radar
                           Terminal System (ARTS) IIIE.10 The cost of this interface is estimated at
                           $1 million. In effect, this interface is a “mini-PAMRI.”




                           7
                            FAA plans to begin replacement of the Host Computer System in fiscal year 1999.
                           8
                            This cost does not include FAA internal costs (e.g., project management, testing) associated with
                           acquiring PAMRI because FAA was unable to provide these costs.
                           9
                            FAA could not provide the full cost of maintaining PAMRI. Instead, FAA officials stated that about
                           $200,000 is spent annually to maintain PAMRI hardware, and about $500,000 is spent annually to
                           maintain PAMRI software at three sites. However, they could not provide the annual cost to maintain
                           PAMRI software at the other 26 sites where PAMRI is operational. We did not evaluate these costs.
                           10
                               CTAS performs flight arrival scheduling. To do this, it must receive flight track data from ARTS IIIE.



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                          Although some of the systems incompatibilities arise from the fact that
                          FAA’s current ATC systems span several generations of computer systems,
                          other incompatibilities are the result of FAA’s failure to adopt and enforce a
                          systems architecture. According to a July 1996 FAA report baselining the
                          ATC data management environment,11 ATC data inconsistencies have
                          resulted from a lack of data standards and policies across the ATC systems.


Myriad of Application     Systems written in many application programming languages are more
Languages Makes           difficult and expensive to modify and maintain than systems written in
Maintenance More Costly   fewer languages. For example, for each language, programming staff must
                          be trained and provided support software (compilers, debuggers, program
and Difficult             libraries, etc.),12 and both the training and suite of support software must
                          be updated and maintained. A software subarchitecture is essential to
                          standardize the languages to be used and to institutionalize process
                          standards or methodologies for designing, coding, testing, and
                          documenting software projects.

                          Software applications associated with 54 operational ATC systems have
                          been written in 53 programming languages (these 53 include 19 assembly
                          languages).13 Since most of the ATC languages are obsolete, there is no
                          readily available cadre of newly trained programmers and current and
                          future maintenance becomes even more difficult and costly. For example,
                          the Automated Radar Terminal Systems (ARTS) are written in Ultra, an
                          obsolete assembly language. Furthermore, no restrictions are currently
                          being placed on application language choices for new systems
                          development. For example, a new system that is currently being
                          developed, the Display System Replacement (DSR), is to be written in three
                          programming languages—Ada, C, and assembly. Ada is not used in any
                          other existing ATC system.



                          11
                           Analysis of Current Information Management Practices for Representative Systems Across NAS
                          Domains (Draft), MITRE, July 1996.
                          12
                            A compiler is a program that translates the source code written by the programmer into object code
                          that can be executed. A debugger is a program that aids in identifying and correcting program errors. A
                          program library is a collection of routines that a programmer can use, as needed, without having to
                          write them anew.
                          13
                            Assembly is a low-level programming language in which each statement corresponds directly to a
                          single machine instruction and is thus specific to a given processor. Assembly languages are used by
                          FAA to meet their stringent real-time requirements. Although modern compilers associated with
                          high-order languages (e.g., C, C++) are capable of meeting some real-time requirements, many are not
                          available for FAA’s legacy systems with unique operating systems and others do not meet FAA’s
                          stringent reliability and fault tolerant requirements.



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                          AUA officials told us that the five AUA IPTs are primarily using C, C++, and
                          Ada to develop new ATC systems. However, we found three additional
                          languages and several versions of assembly language also being used to
                          develop new ATC systems.

                          Software maintenance is a significant FAA expense. To illustrate, the
                          software for the Host Computer System (HCS), its backup—the Enhanced
                          Direct Access Radar Channel (EDARC)—and PAMRI cost $63.6 million
                          annually to maintain.14 Until a software subarchitecture is developed that
                          is based on a systematic analysis of the needs of current and planned
                          operating environments and defines the languages to be used in
                          developing ATC systems, FAA will continue to experience language
                          proliferation and be faced with difficult and costly software maintenance.


ATC Modernization Plans   FAA plans to migrate its highly proprietary ATC systems to open operating
for Evolving to an Open   environments. An open environment is one that is based on
Systems Environment       vendor-independent, publicly available standards. If properly planned and
                          implemented, an open system environment supports portable and
Require a Rigorously      interoperable applications through standard services, interfaces, data
Developed and Complete    formats, and protocols. Although the plan to evolve to an open
Systems Architecture      environment is a wise one, important choices have to be made consistently
                          across ATC systems to derive the expected benefits (e.g., portable
                          applications, system interoperability). In particular, the open system
                          standards for the collective system of systems must be carefully and
                          thoroughly analyzed in light of systemwide requirements, and the most
                          appropriate standards must be selected. The rigor associated with
                          developing a systems architecture can ensure such analysis.

                          Currently, this systemwide analysis is not occurring. Instead, most of the
                          IPTs that are implementing open systems standards are doing so
                          independently. Such a nonstandard migration approach may result in
                          different open system options being selected, perpetuating architectural
                          incompatibilities that require additional costs to overcome. For example,
                          future FAA systems are to provide information to controllers through
                          networked workstations. Two open systems protocol standards that IPTs
                          could independently choose for passing information—ethernet and
                          token-ring—are incompatible.




                          14
                           The $63.6 million includes $22.6 million for FAA software maintenance and $41 million for contracted
                          software maintenance.



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                     Evolution to an open systems environment would also allow FAA to share
                     software among systems with common functionality. For instance, FAA
                     officials told us that 40 percent of the en route flight data processing (FDP)
                     functionality is identical to the oceanic FDP functionality.15 This 40 percent
                     equates roughly to about 60,000 lines of code. To their credit, FAA officials
                     told us that the oceanic and en route IPTs have agreed to look at
                     opportunities to share software between the replacement systems that
                     perform FDP functions. However, without a guiding systems architecture
                     that specifies specific open systems standards, FAA will likely not develop
                     the oceanic and en route replacement systems that are to perform the FDP
                     functions to common standards, thus precluding the opportunity to share
                     software components.


                     Because it has no complete and comprehensive systems architecture to
Conclusions          guide and constrain the ATC systems modernization program, FAA
                     continues to spend nearly $2 billion annually on “stovepipe” systems in an
                     environment where system interoperability is an absolute necessity. To
                     achieve interoperability, FAA is forced to develop and maintain costly
                     system interfaces and incurs higher than need be system development and
                     maintenance costs and reduced systems performance.


                     We recommend that the Secretary of Transportation direct the FAA
Recommendation       Administrator to ensure that a complete ATC systems architecture is
                     developed and enforced expeditiously and before deciding on the
                     architectural characteristics for replacing the Host Computer System.


                     In commenting on a draft of this report, DOT and FAA officials generally
Agency Comments      agreed with our recommendation, which requires FAA to define and
and Our Evaluation   enforce a complete ATC-wide systems architecture. At the same time,
                     however, the officials stated that (1) FAA’s informal mechanisms for
                     attaining system compatibility (e.g., informal communication among
                     system development teams and circulation of individual system
                     specifications among these teams for review and comment) are sufficient
                     and are working well; and (2) the architectural definition efforts underway
                     within individual development teams and these teams’ parent


                     15
                       Currently, the HCS performs FDP functions in the en route business area and the Oceanic Display
                     and Planning System (ODAPS) performs FDP in the oceanic business area. In the future, the
                     HCS-Replacement and the Advanced Oceanic Automation System (AOAS) will perform the FDP
                     functions in their respective environments.



                     Page 48                                                      GAO/AIMD-97-30 Air Traffic Control
Chapter 3
Lack of a Complete ATC Systems
Architecture Impacts ATC Modernization’s
Cost and Performance




organizations, once completed, will effectively augment these informal
processes.

The many examples provided in the report in which FAA incurs added costs
to compensate for system incompatibilities arising from the lack of an ATC
architecture provide clear evidence that FAA’s informal mechanisms are
neither sufficient nor working well; and there is no logical rationale to
support or explain FAA officials’ view that the efforts of the individual
teams will somehow coalesce into an effective approach to ATC-wide
architectural definition and enforcement. It is clear that effectively
modernizing a system of systems as technologically complex, expensive,
interdependent, and safety-critical as the ATC system requires more than
stovepipe architectures linked and enforced by informal communications.
Accordingly, we strongly recommend that FAA formally define and enforce
an ATC-wide systems architecture.

The officials also stated that most of FAA’s legacy systems pre-date the
advent of architectural standards, and that it is thus system age rather than
FAA’s lack of a systems architecture that is primarily to blame for existing
system incompatibilities. As stated explicitly in the report, some
incompatibilities exist because some systems pre-date currently available
technology and standards. However, other system incompatibilities are the
result of FAA’s failure to adopt and effectively enforce a technical
architecture. Furthermore, until FAA completes and enforces its systems
architecture, similar incompatibilities will recur in new ATC systems.

The officials also commented that formally prescribed and enforced
architectural standards could inhibit product team flexibility and creativity
in acquiring ATC systems. They added that while they support the use of
standards and are trying to move in that direction, they prefer a less formal
approach to standards implementation and enforcement. This position has
no merit. A well planned architecture that is enforced in a thoughtful and
disciplined manner ensures compatibility and interoperability among
different systems without unduly constraining internal system
characteristics. The lack of such an architecture fosters not innovation but
incompatibility and waste.




Page 49                                       GAO/AIMD-97-30 Air Traffic Control
Chapter 4

FAA Lacks an Effective Management
Structure and Process to Develop and
Enforce a Systems Architecture
                             FAA’s current approach to ATC architectural development, maintenance,
                             and enforcement is not effective. The office that is responsible for
                             developing and maintaining the NAS, or logical systems architecture, has no
                             budgetary or organizational authority to enforce it, and no FAA
                             organizational entity is responsible for developing and enforcing an
                             ATC-wide technical architecture. As a result, ATC projects can be funded
                             that do not comply with the ATC logical architecture (deviations are not
                             supported by a documented waiver justifying the noncompliance) and
                             there is no complete ATC technical architecture. Until FAA assigns a single
                             organizational entity the responsibility and authority needed to develop,
                             maintain, and enforce an ATC logical and technical systems architecture,
                             FAA will not effectively address ATC system incompatibilities.



                             If a complete systems architecture is to be effectively developed,
FAA Lacks an                 maintained, and enforced, some organizational entity must (1) be assigned
Effective Management         the responsibility and be held accountable for doing so, (2) be given
Structure to Develop,        sufficient resources to accomplish the task, (3) have expertise in
                             information technology, and (4) have organizational and/or budgetary
Maintain, and Enforce        authority over all systems development and maintenance activities. One
a Systems                    model for implementing this is embodied in the Clinger-Cohen Act,1 which
                             requires that major federal departments and agencies establish CIOs that
Architecture                 report to the department/agency head and are responsible for developing,
                             maintaining, and facilitating the implementation of systems architectures.


FAA’s Logical Architecture   FAA  does not have an effective management structure for developing,
Management Structure Is      maintaining, and enforcing a logical ATC systems architecture. The Office
Not Effective                of Systems Architecture and Investment Analysis, which is under the
                             Associate Administrator for Research and Acquisitions, is responsible for
                             developing and maintaining the logical ATC architecture (i.e., the NAS
                             architecture), and has made good progress over the last 2 years in
                             developing and maintaining one (see chapter 3). However, this office is not
                             responsible for enforcing the logical architecture and cannot enforce it
                             because it has neither organizational nor budgetary authority over the IPTs
                             that develop ATC systems or the units that maintain them. (See figure 4.1
                             for the Office of Systems Architecture and Investment Analysis’
                             organizational position in relation to the Administrator, CIO, IPTs, and
                             maintenance activities.)



                             1
                              The 1996 Clinger-Cohen Act, P. L. No. 104-106, section 5125, 110 Stat. 684 (1996).



                             Page 50                                                         GAO/AIMD-97-30 Air Traffic Control
Chapter 4
FAA Lacks an Effective Management
Structure and Process to Develop and
Enforce a Systems Architecture




Page 51                                GAO/AIMD-97-30 Air Traffic Control
                                                                           Chapter 4
                                                                           FAA Lacks an Effective Management
                                                                           Structure and Process to Develop and
                                                                           Enforce a Systems Architecture




Figure 4.1: Office of Systems Architecture and Investment Analysis’ Relative Organizational Position


                                                                                             Administrator
                                                                                                AOA

                                                                Assistant
                                                              Administrator            Deputy Administrator
                                                            for System Safety                 ADA
                                                                   ASY

                                           Assistant                         Assistant                                  Assistant                            Assistant
  Chief Counsel                                                            Administrator                                                                 Administrator for
                                         Administrator                                                                Administrator
      AGC                                                              for Government and                                                               Policy, Planning and
                                        for Civil Rights                                                            for Public Affairs
                                                                          Industry Affairs                                                             International Aviation
                                             ACR                               AGI                                        APA                                    API

                                                                                                                                            Office of Aviation        Europe, Africa and
                                                                                                                                            Policy and Plans          Middle East Office
                                                                                                                                                  APO                       AEU

                                                                                                                                         Office of Environment           Asia-Pacific
                                                                                                                                              and Energy                    Office
                                                                                                                                                  AEE                       APC

                                                                                                                                               Office of                Latin America-
                                                                                                                                         International Aviation        Caribbean Office
                                                                                                                                                  AIA                        ALC

                                                                Associate                Associate
        Associate                  Associate                                           Administrator                                                                    Associate
      Administrator                                           Administrator                                                                                        Administrator for
                                 Administrator                                      for Regulation and
    for Administration                                      for Civil Aviation                                                                                     Air Traffic Services
                                  for Airports                                          Certification
          AAD                                                    Security                                                                                                 ATSa
                                      ARP                                                  AVR
                                                                  ACS


     Office of Business              Office of Airport        Office of Civil                                                                                        Airway Facilities       Office of System
                                                                                     Office of Accident       Air Traffic System
       Information &                  Planning and           Aviation Security                                                           Air Traffic Service
                                                                                       Investigation         Requirements Service                                        Service                 Capacity
        Consultation                  Programming              Intelligence                                                                     AAT
                                                                                            AAI                      ARS                                                  AAF                      ASC
            ABC                            APP                      ACI
                                     Office of Airport        Office of Civil             Aircraft                                              Air Traffic                NAS                Airport Capacity
     Office of Financial                                                                                         Airway Facilities
                                        Safety and           Aviation Security           Certification                                          Resource                 Operations               Planning
          Services                                                                                                Requirements
                                        Standards               Operations                Service                                              Management                  AOP                    ASC-100
            ABA                                                                                                       AFR
                                           AAS                     ACO                       AIR                                                   ATX
      Office of Human                                          Office of Civil           Office of                 Air Traffic                 Air Traffic               Operational             Airspace
          Resource                                           Aviation Security                                    Requirements
                                                                                     Aviation Medicine                                         Operations                 Support             Capacity Planning
       Management                                           Policy and Planning                                       ATR
                                                                                            AAM                                                   ATO                      AOS                   ASC-200
            AHR                                                     ACP

                                                                                      Flight Standards                                      Air Traffic Airspace       NAS Transition
                                                                                                                                               Management                   and
                                                                                           Service
                                                                                                                                                    ATA                Implementation
                                                                                             AFS                                                                            ANS

                                                                                         Office of                                                                     Spectrum Policy
                                                                                        Rulemaking                                            Field Divisions         and Management
                                                                                           ARM                                                                              ASR


                                                                                                                                                                         Resources
                                                                                                                                                                        Management
                                                                                                                                                                           AFZ

                                                                                                                                                                      Aviation System
                                                                                                                                                                         Standards
                                                                                                                                                                            AVN


                                                                                                                                                                       Field Divisions




                           Central                                                                           Northwest                                                                     Mike Monroney
    Alaskan                                       Eastern         Great Lakes       New England                                  Southern             Southwest        Western-Pacific
                           Region                                                                            Mountain                                                                       Aeronautical
    Region                                        Region            Region            Region                                      Region               Region             Region
                            ACE                                                                               Region                                                                           Center
      AAL                                          AEA               AGL               ANE                                         ASO                  ASW                AWP
                                                                                                               ANM                                                                              AMC




                                                                           Page 52                                                                                  GAO/AIMD-97-30 Air Traffic Control
                                                                   Chapter 4
                                                                   FAA Lacks an Effective Management
                                                                   Structure and Process to Develop and
                                                                   Enforce a Systems Architecture




                                                                                                          Associate
                                                                                                        Administrator
                                                                                                      for Research and
                                                                                                        Acquisitions
                                                                                                            ARA


Office of Independent                            Office of Air Traffic       Office of Aviation            Office of                                  Office of System      William J. Hughes
                        Office of Acquisitions                                                                              Office of Information
  Operational Test                                     Systems                   Research             Comm., Navigation,                              Architecture and
                                 ASU                                                                                             Technology                                   Tech Center
    and Evaluation                                  Development                    AAR                 and Surveillance                             Investment Analysis
         ATQ                                             AUA                                            Systems, AND              AIT (CIO)                 ASD                    ACT

                                                                               Chief Scientist         Integrated Product        Corporate                Architecture           Resource
                           Acquisition Policy
                                                   Integrated Product        for Human Factors              Team for            Information               and System            Management
                            and Procedures
                                                   Team for En Route              Division                Infrastructure      Management Div.             Engineering             Division
                               Division
                                                        AUA-200                   AAR-100                   AND-100               AIT-100                  ASD-100               ACT-100
                               ASU-100
                                                                                                       Integrated Product     Integrated Product        Evaluation and
                                                                                  Research                  Team for                                     Configuration        ATC Engineering
                           Quality Assurance       Integrated Product                                                              Team for
                                                                                   Division             Communications                                   Management           and Test Division
                                Division           Team for Terminal                                                         Information Systems
                                                                                  AAR-200                   AND-300                                       ASD-200                 ACT-200
                               ASU-200                  AUA-300                                                                    AIT-200
                                                   Integrated Product            Research and          Integrated Product     Integrated Product       NAS Programming        CNS Engineering
                               Contracts           Team for Weather               Acquisitions              Team for              Team for IT            and Financial
                                Division                                                                                                                                      and Test Division
                                                   and Flight Service        International Division        Surveillance            Services              Management              ACT-300
                               ASU-300                                             AAR-300                  AND-400                 AIT-300                ASD-300
                                                   Systems, AUA-400
                                                                              Airport and Aircraft     Integrated Product     Integrated Product      Investment Analysis        Facilities
                                                   Integrated Product
                                                                              Safety, Research           Team for GPS/            Team for IT           and Operations          Management
                                                   Team for Air Traffic
                                                                              and Development              Navigation             Acquisitions             Research               Division
                                                      Management
                                                                              Division, AAR-400             AND-500                AIT-400                 ASD-400               ACT-400
                                                        AUA-500
                                                                              Aviation Security        Integrated Product                                                    Aviation Simulation
                                                   Integrated Product           Research and                Team for                                                             and Human
                                                    Team for Oceanic            Development             Aircraft/Avionics                                                     Factors Division
                                                        AUA-600               Division, AAR-500             AND-600                                                               ACT-500
                                                                                                                                                                             Airport Management
                                                                                                                                                                               and Emergency
                                                                                                                                                                             Operations Division
                                                                                                                                                                                   ACT-600


                                                                   a
                                                                       ATS is currently being reorganized.




                                                                   Page 53                                                                           GAO/AIMD-97-30 Air Traffic Control
                             Chapter 4
                             FAA Lacks an Effective Management
                             Structure and Process to Develop and
                             Enforce a Systems Architecture




                             FAA officials say that they use the capital investment planning process to
                             enforce the logical architecture. Under this process, various FAA
                             organizations, including the CIO, evaluate and compare competing NAS
                             projects and choose projects to be funded. Four criteria are considered in
                             scoring competing investment options and deciding among them:
                             (1) sponsor (i.e., user) support; (2) mission importance; (3) technology
                             maturity/NAS architecture conformance; and (4) cost effectiveness. Each
                             criterion carries a standard weighting factor that is to be consistently
                             applied to all proposed projects in producing a project score: sponsor
                             support and technology maturity/NAS architecture conformance each carry
                             a weight of 20 percent, while mission importance and cost effectiveness
                             each carry a weight of 30 percent. According to FAA, projects that do not
                             conform to the NAS architecture can be approved under this process. While
                             deviations from the architecture may sometimes be warranted, the
                             decision to waive the requirement for architectural conformance should
                             be made only after careful, thorough, and documented analysis. FAA’s
                             investment process does not require such analysis.

                             FAA has drafted new acquisition management guidance that modifies the
                             above described capital investment planning process. FAA officials stated
                             that the new process will require that ATC projects conform to the logical
                             architecture and that waivers to this requirement will be granted only with
                             convincing and documented justification. This is not the case. The draft
                             guidance permits each team to choose its investment criteria and does not
                             even require that architectural conformance be among them. As a result,
                             this draft guidance does not constitute an effective approach to
                             architectural enforcement.

FAA’s Technical              FAA also lacks an effective management structure for developing,
Architecture Management      maintaining, and enforcing a technical ATC systems architecture. No
Structure Is Not Effective   organization in FAA is responsible for technical ATC architecture. Instead,
                             FAA has permitted a “hodge podge” of independent efforts scattered across
                             its ATC modernization organization to emerge with no central guidance and
                             coordination. For example, the Office of Systems Architecture and
                             Investment Analysis is developing systems security guidance and a menu
                             of architectural standards, while other offices have initiated efforts to
                             develop additional technical architecture guidance (see chapter 3). As a
                             result, there is no ATC-wide technical architecture, and it is unlikely that
                             FAA will produce one in the near future.




                             Page 54                                       GAO/AIMD-97-30 Air Traffic Control
                     Chapter 4
                     FAA Lacks an Effective Management
                     Structure and Process to Develop and
                     Enforce a Systems Architecture




                     Until the authority, responsibility, and resources to develop, maintain, and
Conclusions          enforce a complete ATC systems architecture are clearly assigned to a
                     single FAA organizational entity, FAA will continue to build incompatible
                     and unnecessarily expensive and complex ATC systems.


                     We recommend that the Secretary of Transportation direct the FAA
Recommendation       Administrator to establish an effective management structure for
                     developing, maintaining, and enforcing the complete ATC systems
                     architecture. Specifically, the Administrator should (1) assign the
                     responsibility and accountability needed to develop, maintain, and enforce
                     a complete ATC systems architecture to a single FAA organizational entity,
                     (2) provide this single entity with the resources, expertise, and budgetary
                     and/or organizational authority needed to fulfill its architectural
                     responsibilities, and (3) direct this single entity to ensure that every ATC
                     project conforms to the architecture unless careful, thorough, and
                     documented analysis supports an exception. Given the importance and the
                     magnitude of the information technology initiative at FAA, we recommend
                     that a management structure similar to the department-level CIOs as
                     prescribed in the Clinger-Cohen Act be established for FAA.


                     In commenting on a draft of this report, DOT and FAA officials generally
Agency Comments      agreed with our conclusions and recommendations. However, the FAA
and Our Evaluation   Deputy Director for Architecture and System Engineering stated that FAA
                     is drafting a revision to its investment management policy that, once
                     approved, will change the capital investment planning process and
                     associated investment decision criteria described in our report. Our
                     review of this draft guidance disclosed that it does not require that every
                     ATC project conform to the logical architecture. Instead, the draft guidance
                     permits each team to choose its investment criteria and does not require
                     that architectural conformance be among them.




                     Page 55                                       GAO/AIMD-97-30 Air Traffic Control
Appendix I

Simplified Block Diagrams for the
Near-Term and Mid-Term En Route Centers’
Systems Environment
Figure I.1: Near-Term Environment


                                                                                                                                                  AIRCRAFT
                       ARSR-3/4                            ATCBI-4/5                                    RMSs
                  Primary Surveillance               Secondary Surveillance                          Surveillance
                                                                                     LCU              Navigation        RCL/LDRCL/
                                                                                                                        LINCS/Telco      RCAG
                                                            ARSR-1/2                                   Weather
                                   CD-2 Digital                                                       Automation                          RCE/
                                                       Primary Surveillance
                                                                                                    Communication                        DSRCE

                                            MODE-S                GMCC                  ATCT/LCU          Voice     Data                          BUEC
                                                                   WS                     AFSS                                                     Site
                                                                                                                           External

   TRACON/
   ARTS
                                                                                                                                          RCE/
   ATCT/                                                                                      AMCC             RCOM                      DSRCE
                                   PAMRI                                 MPS
   TDLS                                                                                        WS            (NARACS)
                                                          Users                                                                           MVR/
   FAATC/
                                                                                                                                          DVRS
   IFCN

   ATCT/FDIO                                                            MDT                                                           VSCS
   TRACON/        FDIO/                                                                                                            Comm Switch
   FDIO          CCU/RCU

   NAWPF/                                               EDARC
   PSN             PSN                                                                                                     DMN          BUEC
                           Users                                                      CDC
                                                    Host Computer               DCC/DCCR/DG                                            Back-up
   NAWPF/                                              System                   Display Controls                                      A/G Comm
   AWP
                               FSDPS
   AFSS/
   AFSSWS

                                                                               CRD               PVD
   NAWPF/
                  ADAS
   WMSCR
                                                                                                                         DOTS          ODAPS

   NAWPF/
   WMSCR
                                                                              LAN
                                                              MWP                                                                           TMS
                                              PUP                                                                 PVD
                                                                                                                                            LAN
                                                                                    Briefing Terminals
                                                                                                                             ASD



                                               NEXRAD                     NAWPF/                Weather
               AWOS/           DUATS                                                                                                  VNTSC/ETMS Hub
               ASOS            Vendor        Weather Radar                WMSCR                 Vendor


                                                                              En Route Center

                                                                              Oceanic

                                                                              TMU




                                                    Page 56                                                              GAO/AIMD-97-30 Air Traffic Control
                                              Appendix I
                                              Simplified Block Diagrams for the
                                              Near-Term and Mid-Term En Route Centers’
                                              Systems Environment




                                              Explanatory Notes to Simplified Block Diagram for the Near-term
                                              En Route Centers’ Systems Environment


Systems Within the En Route Center and Their Functions


ADAS              AWOS Data Acquisition System               Collects surface observations data from AWOS and ASOS and
                                                             distributes these data to weather processing and display systems.
AMCCWS            ARTCC (Air Route Traffic Control Center)   Provides capability for real-time and nonreal-time monitoring of en route
                  Maintenance Control Center Workstation     center systems, remote control of equipment and facilities,
                                                             communications/coordination, and system security.
BUEC              Backup Emergency Communications            Provides backup air-to-ground radio voice communications service in
                                                             the event of a failure of the primary or secondary air-to-ground radio
                                                             system.
CCU               Central Control Unit                       Provides flight data input/output print capability.
CDC               Computer Display Channel                   Provides display capability that will be replaced by DSR.
CRD               Computer Readout Display                   Provides display capability that will be replaced by DSR.
DCC               Display Channel Complex                    Provides display capability that will be replaced by DCCR, which will in
                                                             turn be replaced by DSR.
DCCR              Display Channel Complex Rehost             Provides display capability that will replace DCC.
DG                Display Generator                          Provides character and image display capability that will be replaced by
                                                             DSR.
DMN               Data Multiplexing Network                  Provides an inter-facility multiplexed data transmission network.
DSRCE             Down-Scoped Radio Control Equipment        Controls local and remote air-to-ground radios.
DVRS              Digital Voice Recorders                    Make legal recordings of all voice communications between air traffic
                                                             controllers and pilots.
EDARC             Enhanced Direct Access Radar Channel       Provides a backup to HCS for radar processing, and radar track and
                                                             display processing.
FDIO              Flight Data Input/Output                   Provides flight data input/output capability by transferring flight data
                                                             inter-/intrafacility.
FSDPS             Flight Service Data Processing System      Provides the processing capability to support AFSS workstations and
                                                             automated pilot briefings, and maintains a national flight service
                                                             database.
HCS               Host Computer System                       Processes radar surveillance data, associates flight plans with tracks,
                                                             processes flight plans, performs conflict alerts, and processes weather
                                                             data.
MDT               Maintenance Data Terminal                  Provides capability for data entry and display and provides a standard
                                                             serial data interface to connect to a RMS.
MPS               Remote Maintenance and Monitoring          Provides capability for real-time monitoring and alarm notification,
                  System                                     certification parameter data logging, automatic record keeping and
                                                             information retrieval, and trend analysis, failure anticipation, remote
                                                             control of equipment and facilities, diagnostic and fault isolation, remote
                                                             adjustments, and system security.
MWP               Meteorologist Weather Processor            Provides weather data processing and display.
MVR               Multi-Channel Voice Recorders              Make legal recordings of all voice communications between air traffic
                                                             controllers and pilots.
                                                                                                                              (continued)


                                              Page 57                                                GAO/AIMD-97-30 Air Traffic Control
                                               Appendix I
                                               Simplified Block Diagrams for the
                                               Near-Term and Mid-Term En Route Centers’
                                               Systems Environment




Systems Within the En Route Center and Their Functions


NARACS            National Radio Communications System        Provides minimum essential command, control, and communications
                                                              capabilities to direct the management, operation, and reconstitution of
                                                              the National Airspace System during a national or local emergency.
PAMRI             Peripheral Adapter Module Replacement       Provides interfacing capability to HCS.
                  Item
PSN               Packet Switch Network                       Provides communication network for transmitting data via addressed
                                                              packets.
PUP               Principal User Processor                    Provides the capability to request and display NEXRAD weather data.
PVD               Plan View Display                           Provides aircraft situation display capability for the controller that is to be
                                                              replaced by DSR.
RCE               Radio Control Equipment                     Controls local and remote air-to-ground radios.
RCU               Remote Control Unit                         Provides FDIO remote print capability.
RCOM              Recovery Communications                     Provides National Radio Communications System emergency
                                                              communications essential during and after earthquakes, hurricanes, and
                                                              tornadoes.
VSCS              Voice Switching and Control System          Provides air-to-ground and voice communication services and
                                                              ground-to-ground voice communication services between controllers,
                                                              other ATC personnel, and others at the same and different en route
                                                              centers and other ATC facilities.


Oceanic ATC Systems Within an En Route Center


DOTS              Dynamic Ocean Track System                  Provides track generation and traffic display as part of the Oceanic
                                                              Traffic Planning System.
ODAPS             Oceanic Display and Planning System         Oceanic system that displays aircraft position based on extrapolations
                                                              from flight plans.



Traffic Management Unit (TMU) Systems Within an En Route Center


ASD               Aircraft Situation Display                  Provides a display showing the location of aircraft across the country
                                                              that is used for strategic planning purposes.
TMS               Traffic Management System                   Provides national level management and monitoring of the airspace
                                                              system, including air traffic flow, aircraft operations, and en route sector
                                                              and airport utilization and loading.




                                               Page 58                                                 GAO/AIMD-97-30 Air Traffic Control
Appendix I
Simplified Block Diagrams for the
Near-Term and Mid-Term En Route Centers’
Systems Environment




Systems and Facilities Outside but Interfacing With an En Route Center


AFSS                                         Automated Flight Service Station
AFSSWS                                       Automated Flight Service Station
                                             Workstation
ARSR-1                                       Air Route Surveillance Radar - 1
ARSR-2                                       Air Route Surveillance Radar - 2
ARSR-3                                       Air Route Surveillance Radar - 3
ARSR-4                                       Air Route Surveillance Radar - 4
ARTS                                         Automated Radar Terminal System
ASOS                                         Automated Surface Observing System
ATCBI-4                                      Air Traffic Control Beacon Interrogator - 4
ATCBI-5                                      Air Traffic Control Beacon Interrogator - 5
ATCT                                         Airport Traffic Control Tower
AWOS                                         Automated Weather Observing System
AWP                                          Aviation Weather
                                             processor
CD                                           Common Digitizer
DUATS                                        Direct User Access Terminal System
ETMS                                         Enhanced Traffic Management System
FAATC                                        FAA Technical Center
GMCCWS                                       General NAS Maintenance Control Center
                                             Workstation
IFCN                                         Interfacility Flow Control Network
LCU                                          Local Control Unit
LINCS                                        Leased Interfacility NAS Communications
                                             System
LDRCL                                        Low Density Radio Communications Link
MODE-S                                       Mode Select
NAWPF                                        National Aviation Weather Processing
                                             Facility
NEXRAD                                       Next Generation Weather Radar
RCAG                                         Remote Center Air-to-Ground
RCL                                          Radio Communications Link
RMS                                          Remote Monitor System
TDLS                                         Tower Data Link Service
Telco                                        Telecommunications
TRACON                                       Terminal Radar Approach Control
VNTSC                                        Volpe National Transportation Systems
                                             Center
WMSCR                                        Weather Message Switching Center
                                             Replacement


Page 59                                              GAO/AIMD-97-30 Air Traffic Control
                                                          Appendix I
                                                          Simplified Block Diagrams for the
                                                          Near-Term and Mid-Term En Route Centers’
                                                          Systems Environment




Figure I.2: Mid-Term Environment


   NEXRAD                                                                          Sensors / Interfaces
                                      Surveillance
 Weather Radar                                                        M-2
                                  • ARSR-4                                                                                                           GEO
                                                                      M-3                                                          GPS
                                  • ADS-B                                                To WAAS
                                                                        WMSCR
           Weather Data           • MODE-S/Monopulse                                     To Navaid Mon.
                                                                       (NAWPF)
           • Lightning                                                                                                                                  From WAAS
           • Satellite                                                            M-4                                                         TCAS
           • NWS                                                                  M-5                     Mode S       FMS
                                    TA-7             Maint. Monitor
                                                                                  M-11
                                    AR-1
                           TA-5                                                   GW                                                                        INTERFACES
                           AR-2        Multi-Sensor                   AC-4                      Data Comm                   Voice Comm
                                        Processor                                               • MODE-S D/L                • VHF Analog
                       ADAS             (Enroute)                                               • VHF TDMA                  • VHF TDMA               TOWER
                                                                                                                                                     TA-1   NAVAID Monitor
                                                                                                                                                     TA-2   MPS
                                                                         NADIN
                                                                                                             Data               Voice                TA-3   SMA
       WARP                                                               PSN
                                                                                                 M-10                                                TA-4   ADL
                                                                                                                                                     TA-5   ITWS
                                        EDARC Repl.                                                  DLP                                  ICSS
                                                                                                                       VSCS                          TA-6   Surv. Sensors
                                                                                                    Router                               Type 3      TA-7   Surv. Sensors
                                             Host                        To MPS
                                                                                                TA-4
                                                                                                                                                     TRACON
                                      Replacement                                               AC-5
                                                                                                                                                     AR-1 MIP (ASR) (Sur. Fusion)
                                                                                                                                                     AR-2 ITWS
                                                                                                                                                     AR-3 STARS

     CWSU                                                   UBI                                                                                      ATCSCC
                                                                                                                      DSR                            AC-1   ODMS
                                                                                                                                                     AC-2   TMP/ETMS/ODMS
    From GPS              ADL                  DSP                    ETMS                  CTAS                            AC-1        OASIS        AC-3   MPS
                                                                                                                                                     AC-4   NADIN PSN
                                                                                                 TA-3                                                AC-5   DLP Router
                                  Conflict                  TFM
                                                                                            ITWS          AC-2               M-1
                                                                                                                                        DUATS        Miscellaneous
      Navaid Monitor               Probe                    LAN
                                                                                            Display       AR-3               M-2                     M-1    Pilots
      • TACAN
                                                                                                                                                     M-2    NWS
      • VOR/DME
                                               TA-2 AC-3                                                                                             M-3    Ext. Users
      • GPS/WAAS                   MPS                                                                    WAAS                                       M-4    AOC
                                                                                    From GPS
                                                    NADIN PSN                                                           To GEO Satelite              M-5    ARINC PSN
                                                                                                                                                     M-10   FAA Transmis. Facil.
                                                                                         TA-1
                                                                         • OCC                          Maintenance     TA-6                         M-11   ADTN
                                                                         • NOCC                           Monitor
                                                                                                                             Surveillance Systems




                                                          Page 60                                                                         GAO/AIMD-97-30 Air Traffic Control
                                              Appendix I
                                              Simplified Block Diagrams for the
                                              Near-Term and Mid-Term En Route Centers’
                                              Systems Environment




                                              Explanatory Notes to Simplified Block Diagram for the Mid-term
                                              En Route Centers’ Systems Environment


Systems Within the En Route Center and Their Functions


ADAS              Automated Weather Observing System         Collects surface observation data from AWOS and automated surface
                  (AWOS) Data Acquisition System             observing system (ASOS) and distributes these data to weather
                                                             processing and display systems.
ADL               Aeronautical Data Link                     Provides the capability to transfer data in digital form between the
                                                             aircraft and the ground or between aircraft by means other than voice
                                                             communications.
CTAS              Center Terminal Radar Approach Control Maximizes use of airport capacity by providing decision aids to en route
                  (TRACON) Automation System             and terminal controllers.
CWSU              Center Weather Service Unit                This is the area in the en route center where the meteorologists perform
                                                             their functions using the various systems that provide them with weather
                                                             information.
DLP               Data-Link Processor                        Supports networked aeronautical telecommunications services within
                                                             United States domestic and oceanic airspace.
DSP               Departure Sequencing Program               Calculates departure sequence, from push-back to time over fix, and
                                                             includes runway configuration, gate position, aircraft performance, and
                                                             flow restrictions, for a group of airports. Displays departure sequence
                                                             lists in towers and at the Traffic Management Unit (TMU).
DSR               Display System Replacement                 Provides modern ATC workstations to support programs like Weather
                                                             and Radar Processor (WARP), Automated En Route Air Traffic Control
                                                             (AERA), CTAS, and Data Link. Provides new controller data entry and
                                                             display devices. Provides an interface capability with the Host computer
                                                             and system and the Enhanced Direct Access Radar Channel (EDARC).
DUATS             Direct User Access Terminal System         Provides the pilot with convenient access to pre-flight aeronautical and
                                                             weather information to plan the flight. Also allows pilots to input
                                                             instrument flight rules (IFR), International Civil Aviation Organization
                                                             (ICAO), or Visual Flight Rules (VFR) flight plans into the system .
EDARC             Enhanced Direct Access Radar Channel       Provides a backup to the host computer system (HCS) for radar
                                                             processing, and radar track and display processing.
ETMS              Enhanced Traffic Management System         Provides national monitoring, prediction, planning, re-routing, “ground
                                                             hold”, and flow management.
GEO               Geostationary Satellite                    Provides satellite-based air-to-ground and ground-to-ground
                                                             communications capability.
GPS               Global Positioning System                  Provides global navigation signals for use in determining 4-D
                                                             (dimensional) time/position data.
GW                Gateway                                    Communications system interface between the En Route Center and
                                                             external systems.
HOST              Host Computer System Replacement           Will process radar surveillance data, associate flight plans with tracks,
Replace-ment                                                 process flight plans, perform conflict alerts, and process weather data.
ICSS              Integrated Communication Switching         Provides voice communication services between controllers and aircraft
                  Systems                                    (air-to-ground), and between controllers and other personnel within or
                                                             among different ATC facilities, such as towers, TRACONs, and Flight
                                                             Service Stations (ground-to-ground).
                                                                                                                             (continued)


                                              Page 61                                               GAO/AIMD-97-30 Air Traffic Control
                                             Appendix I
                                             Simplified Block Diagrams for the
                                             Near-Term and Mid-Term En Route Centers’
                                             Systems Environment




Systems Within the En Route Center and Their Functions


ITWS              Integrated Terminal Weather System        Provides integration of terminal area weather products and displays.
MODE-S            Mode Select                               Provides addressable-beacon interrogation and reply.
MODE-S D/L        Mode Select Data Link                     Provides the capability for digital communications between aircraft,
                                                            various air traffic control functions, and weather databases through a
                                                            digital interface with the ATC automation system.
MPS               Maintenance Processor Subsystem           Provides capabilities for real-time monitoring and alarm notification,
                                                            certification parameter data logging, automatic record keeping and
                                                            information retrieval and trend analysis, failure anticipation, remote
                                                            control of equipment and facilities, diagnostic and fault isolation, remote
                                                            adjustments, and system security.
NADIN PSN         National Airspace Data Interchange        Provides a packet-switched wide-area data communications network
                  Network (Packet Switch Network)           which interconnects major ATC facilities.
NEXRAD            Next Generation Radar                     Provides precipitation, wind velocity, and turbulence data sensing and
                                                            processing.
OASIS             Operational and Supportability            Replaces several systems, (the Flight Service Automation System,
                  Implementation System                     Aviation Weather Processor, and the Flight Service Data Processing
                                                            System).
TACAN             Tactical Air Navigation                   Provides line-of-sight ultra high frequency (UHF) bearing and range data
                                                            to aircraft.
TFM LAN           Traffic Flow Management Local Area        Provides communciations system for ATC traffic flow managment
                  Network                                   personnel responsible for management and monitoring of current air
                                                            traffic flow, aircraft operations, en route sector and airport utilization and
                                                            loading, and future system utilization.
TRACON            Terminal Radar Approach Control           ATC facilities that sequence and separate aircraft as they approach and
                                                            leave busy airports, beginning about 5 nautical miles and ending about
                                                            50 nautical miles from the airport, and generally up to 10,000 feet above
                                                            the ground, where en route centers’ control begins.
UBI               User Benefits Infrastructure              Host computer system interface device and en route center local area
                                                            network that establishes a common interface to the host computer and
                                                            an updated telecommunications infrastructure.
VHF TDMA          Very High Frequency Time Division         Provides digital communications capability using the VHF radio band.
                  Multiple Access
VOR DME           Very High Frequency Omnidirectional       The VOR supports determination of aircraft position and airway definition
                  Range with Distance Measuring             by transmitting azimuth signals. The DME provides slant range between
                  Equipment                                 the aircraft and the DME locations.
VSCS              Voice Switching and Control System        Provides a voice communications system which performs the intercom,
                                                            interphone, and air/ground voice connectivity and control functions
                                                            needed for ATC operations in an en route center.
WAAS              Wide Area Augmentation System             Transmits wide area differential corrections for GPS signals. Provides the
                                                            capability to use GPS for precision runway approach guidance.
WARP              Weather And Radar Processor               Collects, processes and disseminates NEXRAD and other weather
                                                            information to controllers, traffic management specialists, pilots, and
                                                            meteorologists. It will provide a mosaic product of multiple NEXRAD
                                                            information to DSR for display with aircraft targets.




                                             Page 62                                                 GAO/AIMD-97-30 Air Traffic Control
Appendix I
Simplified Block Diagrams for the
Near-Term and Mid-Term En Route Centers’
Systems Environment




Systems and Facilities Outside but Interfacing With an En Route Center


ADS-B                                        Automated Dependent
                                             Surveillance—Broadcast
ADTN                                         Aeronautical Data Transmission Network
AOC                                          Airline Operations Center
ARINC PSN                                    Aeronautical Radio Inc. Packet Switched
                                             Network
ARSR-4                                       Air Route Surveillance Radar-4
ASR                                          Airport Surveillance Radar
FMS                                          Flight Management System
NAVAID                                       Navigational Aid System
NAWPF                                        National Aviation Weather Processing
                                             Facility
NEXRAD                                       Next Generation Weather Radar
NOCC                                         National Operational Control Center
NWS                                          National Weather Service
OCC                                          Operational Control Centers
ODMS                                         Operational Data Management System
SMA                                          Surface Movement Advisor
STARS                                        Standard Terminal Automation
                                             Replacement System
TCAS                                         Traffic Alert and Collision Avoidance
                                             System
TMP                                          Traffic Management Processor
WMSCR                                        Weather Message Switching Center
                                             Replacement




Page 63                                              GAO/AIMD-97-30 Air Traffic Control
Appendix II

Architectural Characteristics of Current and
Near-Term Key Enroute Systems


                                                                                                 Database
Existing and                                                             Application             management
near-term systems     Hardware               Operating system            languages               system                Communications
Host Computer         IBM 3083 mainframe FAA unique which                Jovial, BAL, Fortran,   NAS unique version    370 channel
System (HCS)          with some special  has evolved from                PL/1                    of data base
                      micro-code         early IBM DOS                                           management and/or
                                                                                                 COMPOOL
                                                                                                 management
Peripheral Adapter    IBM 3710               N/A                         N/A                     N/A                   RS-232, RS-422,
Module Replacement                                                                                                     byte parallel, bit
Item (PAMRI)a                                                                                                          serial (modem) for
                                                                                                                       incoming radar
Computer Display      FAA unique (Custom FAA unique (Custom FAA unique (Custom FAA unique (Custom 370 Channel
Channel (CDC)         Raytheon product)  Raytheon operating Raytheon language) Raytheon data
                                         system)                               management
                                                                               software)
Display Channel       Highly modified IBM    FAA unique (running Jovial, Assembly                FAA unique (Custom 370 Channel
Complex (DCC)         System 360/65 with     prototype of HCS                                    data management
                      Model 50 I/O           operating system)                                   software)
                      Controller
Direct Access Radar   FAA unique (Custom FAA unique (Custom FAA unique (Custom                   FAA unique (Custom To Host through
Channel (DARC)        made Raytheon      Raytheon operating Raytheon language)                   Raytheon data      PAMRI, RS-422 for
                      product based on   system)                                                 management         input from RDDU
                      Motorola 68000                                                             software)
                      processors)
Display System        IBM RS/6000            IBM AIX version             Ada, C, Assembly        Oracle                TCP/IP, ISO/OSI
Replacement (DSR)     workstations           3.2.5 with kernel           language                                      version B0 with FAA
                                             modifications for                                                         options, Frame
                                             real-time                                                                 Relay (ANSI 617,
                                             performance                                                               618), IEEE 802.3
                                                                                                                       CSMA/CD, IEEE
                                                                                                                       802.5 token ring,
                                                                                                                       370 channel,
                                                                                                                       RS-422, IEEE 488,
                                                                                                                       VSCS interface
Weather and Radar     Sun Ultra Enterprise   Sun Solaris (at least       ANSI C                  none                  TCP/IP, ISO 8802.3
Processor (WARP)      5000 server            version 2.5)
                                             a
                                                 PAMRI is a hardware/firmware data/protocol converter.




                                             Page 64                                                      GAO/AIMD-97-30 Air Traffic Control
Appendix III

Major Contributors to This Report


                       Randolph C. Hite, Senior Assistant Director
Accounting and         Keith A. Rhodes, Technical Assistant Director
Information            Madhav S. Panwar, Senior Technical Advisor
Management Division,   David A. Powner, Senior Information Systems Analyst
                       Robert C. Reining, Senior Information Systems Analyst
Washington, D.C.




(511488)               Page 65                                    GAO/AIMD-97-30 Air Traffic Control
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