LIDAR-based F-factor for wind shear alerting: different smoothing algorithms and application to departing flights.

ABSTRACT Rapid fluctuations of wind shear hazard factor (or F-factor) calculated from the headwind profile measured by Doppler Light Detection and Ranging ( LIDAR) may make it difficult for use in wind shear alerting at an airport such as Hong Kong International Airport ( HKIA). Preprocessing by flight simulator or post-processing by averaging over a certain length are attempted in this study to smooth the F-factor and enhance its skills on wind shear alerting. The F-factor so obtained is used for alerting of wind shear (headwind change exceeding 15 knots) for departing flights. Through case studies and statistical studies, the LIDAR-based F-factors are found to have good correlation with the F-factor determined from flight data (the Quick Access Recorder, or QAR, data from the commercial jets). Using the relative operating characteristics ( ROC) curves, the LIDAR-based F-factor obtained by smoothing over a window size of 300-500 m is found to have good skills in wind shear alerting, and the performance is comparable with, or even better than, the LIDAR-based F-factor using the flight simulator approach. By choosing an optimal alerting threshold specific for each runway corridor, the F-factor successfully alerts 86% of pilot wind shear reports with the percentage of time on alert of 12%, which is found to be satisfactory for real-time use. The performance of the F-factor on stronger wind shear (headwind change of 25 knots or more) is also studied. [ABSTRACT FROM AUTHOR]