Aviation Weather:

FAA Needs to Resolve Questions Involving the Use of New Radars

RCED-90-17: Published: Oct 12, 1989. Publicly Released: Oct 20, 1989.

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Pursuant to a congressional request, GAO provided information about the Federal Aviation Administration's (FAA) progress in disseminating hazardous weather data from three new weather-related systems, focusing on: (1) FAA progress in preparing the necessary operational procedures for the Airport Surveillance Radar (ASR-9) weather channel and the Terminal Doppler Weather Radar (TDWR); and (2) the status and availability of weather services FAA intended to provide through the Aeronautical Data Link.

GAO found that FAA: (1) did not implement formal procedures for transmitting ASR-9 weather data from controllers to pilots, although the first ASR-9 radar was operational and FAA planned to deploy additional radars; (2) believed that controllers needed to experience basic changes in ASR-9 precipitation detection capabilities before it issued formal procedures, and did not believe that the absence of operational procedures hindered controllers' use of ASR-9, although controllers lacked guidance regarding how often to use ASR-9 or how to interpret the precipitation display; (3) did not require controllers to use ASR-9 weather information to reroute planes, although the improved weather detection capability could help controllers anticipate the need to reroute planes around adverse weather; (4) planned to install the first TDWR unit by June 1993, and install 47 additional units over the following 3 years; (5) is evaluating data dissemination procedures as part of its TDWR operational testing, since it and the airline industry are concerned about the adequacy of using its current, less capable weather system's procedures to alert pilots of events identified by TDWR; and (6) planned to provide hazardous weather advisories through its Aeronautical Data Link, although its significant delay, due to its reliance on other delayed information systems, could require additional operational testing.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: ASR-9 operational procedures are in place, according to FAA. FAA has initiated an interagency process to identify end-users' requirements. Since operational procedures are in effect, no interim procedures are needed. An accomplishment report had been drafted but not approved, as of September 1990.

    Recommendation: To ensure the consistent dissemination and use of new weather data available from ASR-9, the Secretary of Transportation should direct the Administrator, FAA, to: (1) establish time frames for issuing ASR-9 operational procedures; (2) convene a joint government/industry user group, similar to that used for TDWR, to resolve uncertainties regarding the use and dissemination of ASR-9 weather data; and (3) issue interim guidelines if significant ASR-9 implementation will occur before final procedures are developed.

    Agency Affected: Department of Transportation

  2. Status: Closed - Not Implemented

    Comments: FAA's Air Traffic organization does not believe adoption of this recommendation is feasible because the pilot in command is directly responsible for the safe operation of an aircraft, as specified in Federal Aviation Regulation 91.3. Air Traffic believes it is essential for this responsibility to continue to reside with the pilot because they are in the best position to assess all factors.

    Recommendation: The Secretary of Transportation should direct the Administrator, FAA, to evaluate, during subsequent operational tests of TDWR, the impact and efficiency of having controllers direct aircraft around microbursts. The agency could then resolve the policy question concerning the dissemination of microburst warnings and therefore implement the most effective operational procedures.

    Agency Affected: Department of Transportation


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