Publications

In this paper, the revised RAPT algorithm and display are described and evaluated. The fidelity of the RAPT operational model is assessed by comparing RAPT departure status with observed departure flows (i.e., trajectories, weather avoidance maneuvers and storm penetrations) on several days when convective weather SWAPs were in effect in New York. Real-time in-situ observations at RAPT facilities (described in a companion paper at this conference; Robinson, 2008), user feedback from RAPT playbacks and the REPEAT web site are used to support this post-event evaluation. For example, real time observations provide the time and operational rationale for a specific departure route closure identified in the traffic flow analysis. This information is necessary to identify closures or flow restrictions that are the result of factors outside of the current RAPT algorithm domain (e.g., traffic restrictions due to volume, downstream congestion, etc.). Real time observations are also used to identify specific times when critical, weather-related operational decisions were made. The RAPT guidance at these critical decision points is analyzed to determine if RAPT provided information that enabled (or could have enabled, had it been used) more timely or effective decisions. The effect of forecast uncertainty on RAPT performance is also examined, particularly in convective weather situations where the location, severity and operational impact were difficult to predict. Strategies that mitigated risks associated with forecast uncertainty are presented. These include the use of additional information provided in the RAPT display, such as echo top heights encountered along the departure route, to confirm or modify RAPT guidance and the consideration of the departure status of two or more adjacent routes to 'average out' variations in the departure status timelines.

This paper gives a brief overview of the history of the development of the TDWR/LLWAS 3 integration algorithms, a brief overview of the various algorithms, and a discussion of the comparative evaluation of the TDWR, LLWAS 3, and the three candidate TDWR/LLWAS 3 integration algorithms. This is followed by a more detailed description of the TDWR/LLWAS 3 integration algorithm chosen by the FAA for production, and a brief overview of the ITWS/LLWAS 3 integration algorithm.

In 1993 the Federal Aviation Administration (FAA) began deploying two new wind shear detectionsystems: the Terminal Doppler Weather Radar (TDWR) and the third-generation Low Level Windshear Alert System (LLWAS 3). Currently, nine airports are scheduled to receive both a TDWR and an LLWAS 3. This number may eventually increase to as high as 45. When co-located, the systems will be integrated to provide a single set of wind shear alerts and improve system performance. The TDWR production schedule required one of three integration algorithms to be chosen for specification by fall 1991. The three algorithms are the prototype integration algorithm developed at the National Center for Atmospheric Research (NCAR) and two algorithms developed at MIT Lincoln Laboratory (MIT/LL). To assess the performance of the three algorithms, MIT/LL performed a study of the integration, TDWR, and LLWAS 3 algorithms at Orlando International Airport in the summer of 1992. We discuss results of the 1991 comparative study and a follow-up study of the TDWR, LLWAS 3, and Message Level integration algorithms at Orlando in 1992. All of the algorithms met the requirement of detecting 90 percent of microburst level wind shear with loss events. LLWAS 3, Build 5 TDWR, and the MIT/LL integration algorithms run with Build 5 TDWR, all met the requirement that less than 10 percent of wind shear alerts be false. The NCAR prototype did not utilize Build 5 TDWR. Build 4 TDWR and all integration algorithms run with Build 4 TDWR did not meet the false-alert requirement. Detailed descriptions of the algorithms are given. The methodology for estimating various algoirthm performance statistics based on a comparison with a dual-Doppler algorithm is detailed.

In 1993 the FAA will begin deploying the Terminal Doppler Weather Radar (TDWR) at selected airports in the United States. Forty-five TDWRs will be collocated with LLWAS 3 systems, and the FAA has decided that all TDWRs collocated with LLWAS 3 systems must be integrated with LLWAS 3 prior to commissioning. The algorithm chosen to perform this integration must be supplied with a set of site-specific parameters. This report gives guidance on how to set the values of theme integration parameters.