Air Traffic Control:

Computer Capacity Shortfalls May Impair Flight Safety

IMTEC-89-63: Published: Jul 6, 1989. Publicly Released: Jul 17, 1989.

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Pursuant to a congressional request, GAO evaluated the Federal Aviation Administration's (FAA) computer systems capability to minimize the possibility of near mid-air collisions, focusing on: (1) how FAA managed computer capacity in existing terminal systems; and (2) whether FAA assessed capacity limitation in terminal systems that could preclude effective implementation of planned safety enhancements intended to reduce near mid-air collisions.

GAO found that: (1) there were widespread computer shortfalls at terminal area facilities that FAA did not recognize until controllers began experiencing lost, flickering, or delayed data on their displays; (2) the shortfalls occurred because FAA lacked a computer capacity and performance management program to monitor Terminal Radar Approach Control (TRACON) system performance and to determine future requirements; (3) FAA concluded that it did not need the program because it believed that the existing systems would meet requirements until an advanced system would replace it in the next decade; (4) FAA could not predict computer shortfalls, since it did not measure computer utilization or test software enhancements under the heaviest work loads; (5) FAA improved software and postponed some less critical functions in an attempt to alleviate capacity shortfalls at some terminals; (6) FAA did not adequately assess the resources necessary to accommodate future traffic growth, the Mode C Intruder function, and additional Mode C-equipped aircraft; and (7) the current sole-source contract to increase computer capacity was not an ideal solution, since it included purchasing equipment that was no longer manufactured and might not meet FAA needs.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: DOT stated that FAA plans to use the results of the newly developed monitoring tool and any other performance management system it develops as a basis for all future procurements.

    Recommendation: After implementing the program and identifying the work-load requirements for TRACON, the Secretary of Transportation should direct the Administrator, FAA, to ensure that all future procurements of hardware and software are determined by these requirements.

    Agency Affected: Department of Transportation

  2. Status: Closed - Implemented

    Comments: The Department of Transportation (DOT) stated that the capabilities of the Technical Center would be increased to ensure that a sufficient number of displays can be configured into the system.

    Recommendation: The Administrator, FAA, should ensure that the FAA Technical Center test facility uses configurations that more accurately replicate the processors, displays, and traffic at the busiest operational sites to ensure that approved software functions will work.

    Agency Affected: Department of Transportation: Federal Aviation Administration

  3. Status: Closed - Implemented

    Comments: The Department of Transportation stated that, while FAA studies were not as formal as GAO expects, it believed that FAA had already thoroughly analyzed short-term and long-term capacity requirements. However, FAA had not thoroughly analyzed these requirements.

    Recommendation: The Secretary of Transportation should direct the Administrator, FAA, to implement a computer capacity and performance management program for TRACON computer systems, including conducting comprehensive analyses of the utilization, processing capacity, and input/output rates of present and projected work loads. Analyses of future work loads should include the full impact of the expanded Mode C rule.

    Agency Affected: Department of Transportation

  4. Status: Closed - Implemented

    Comments: FAA has implemented a software performance monitor at 49 of its 63 largest sites. This will provide FAA with some data on current work loads, but this is not a complete computer capacity and performance management program.

    Recommendation: The Secretary of Transportation should direct the Administrator, FAA, to implement a computer capacity and performance management program for TRACON computer systems, including analyzing trends in data processing work loads to determine when existing system capacities will be saturated.

    Agency Affected: Department of Transportation

  5. Status: Closed - Implemented

    Comments: FAA has taken actions in response to this recommendation, including assessing computer processing inefficiencies, identifying the busiest TRACONs, directing the busiest TRACONs to develop contingency plans to respond to capacity shortfalls, and procuring solid-state memories.

    Recommendation: To address existing shortfalls that currently threaten the ability of controllers to maintain separation of aircraft, the Secretary of Transportation should direct the Administrator, FAA, to take necessary actions to ensure that critical air traffic control functions are not interrupted by capacity shortfalls. Initially, this involves gathering and reporting important capacity-related data, identifying quickly those TRACON that have the most urgent problems and, in concert with TRACON officials, identifying potential solutions to the problems. Identification of potential solutions should include considering those temporary measures that have been successfully used at selected TRACON, as well as other approaches to reduce work loads.

    Agency Affected: Department of Transportation

  6. Status: Closed - Implemented

    Comments: DOT stated that an analysis of alternatives had already been done in 1987. In addition, DOT stated that an analysis was being conducted to determine the need to upgrade ARTS IIIA systems for consolidated TRACON under development.

    Recommendation: Because a new advanced system is not scheduled to replace existing TRACON systems until the mid-to-late 1990s, the Secretary of Transportation should direct the Administrator, FAA, to perform a complete analysis of all available alternatives for meeting the larger TRACON air traffic requirements for at least the next 10 years. Recognizing that the existing Automated Radar Terminal System (ARTS) IIIA design is over 15 years old, this analysis should seek to identify the most cost-effective solution for meeting FAA requirements.

    Agency Affected: Department of Transportation

 

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