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; 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. As a result, the IPTs have been left to proceed individually in setting architectural standards and developing and evolving systems. Without an ATC-wide technical architecture, FAA’s ATC systems have and will continue to suffer from costly and inefficient incompatibilities. Lack of a Technical Systems Architecture Means Costly System Incompatibilities

The lack of a complete systems architecture has produced architectural differences and incompatibilities among ATC systems, such as different communication protocols and proprietary operating environments, 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. 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. 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. However, other system incompatibilities are the result of FAA’s failure to adopt and effectively enforce a technical architecture. FAA’s Logical Architecture Management Structure Is Not Effective

FAA does not have an effective management structure for developing, maintaining, and enforcing a logical ATC systems architecture. This is not the case.
Why GAO Did This Study

GAO reviewed the Federal Aviation Administration's (FAA) air traffic control (ATC) modernization effort, focusing on: (1) whether FAA has a target architecture 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.

What GAO Found

GAO found that: (1) FAA lacks a complete systems architecture, or overall blueprint, to guide and constrain the development and maintenance of the many interrelated systems comprising its ATC infrastructure; (2) FAA is developing one of the two principal components of a complete systems architecture, 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; (3) 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; (4) 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; (5) overcoming these incompatibilities means "higher than need be" system development, integration, and maintenance costs, and reduced overall systems performance; (6) 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; (7) this not only increases software maintenance costs but also effectively precludes sharing software components among systems; (8) without a technical architecture specifying the information technology standards and rules, the opportunity to share software will likely be lost; (9) 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; (10) other system incompatibilities are the result of FAA's failure to adopt and effectively enforce a technical architecture; (11) by failing to formulate a complete systems architecture, FAA permits and perpetuates inconsistency and incompatibility; (12) 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; (13) FAA's management structure for developing, maintaining, and enforcing an ATC systems architecture is not effective; and (14) instead, processes now in place permit the acquisition of architecturally non-compliant systems without special waiver of architectural standards.