21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-6.5.3

AN IMPROVED TECHNIQUE FOR FLIGHT PATH AND GROUNDSPEED ANALYSIS USING RECORDED RADAR DALA

Orloff K. L., Bruno A. E.
Orloff Consulting, USA

Keywords: flight path, ground speed, radar, flight path

Recorded radar data retrieved from air traffic control facilities are often used in aviation accident investigation and reconstruction for the purpose of determining an aircraft's flight path and groundspeed. Simple averaging methods for smoothing the flight path and extracting groundspeed are shown to yield unsatisfactory results. In this paper, improved methods are presented which allow for a more accurate determination of both the times of the radar returns for long-range data, and more accurately establish the flight paths for either long-range radar data or terminal radar data. Least-squares moving-arc methods are applied in order to 1) adjust for azimuth and range errors that are inherent in recorded radar data, and 2) to smooth the flight path. Groundspeed and true course, as computed from the adjusted and smoothed flight path, are further smoothed by means of multipoint weighted averaging. Weighting functions and end-point handling methods are suggested that have proven successful at minimizing anomalous end-point excursions. Sample sets of actual recorded radar data are used to illustrate the application of the above techniques. For the example of terminal radar data, the groundspeed and true course are compared with the recorded output from the aircraft's digital flight data recorder.

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