A Crosswind Hazard Study with Using FDR Data

In order to characterize the crosswind hazard, there is a need to develop an effective index that can suitably reflect the degree of the hazard. A Boeing 737-800 which was threatened by a crosswind was evaluated in this study based on a set of flight data recorder (FDR) data. The data consisted of Inertial Navigation System (INS) measurements, radio altitude, ground position and speed, drift angle, and air data. To determine these characteristics, the data were processed with using a 24-state extended-Kalman-filter (EKF) to reconstruct the wind profile along the flight path. The result shows that the wind speed started decreasing 30 seconds before the landing and sharply decreased during the flare period while the wind direction changed rapidly during the final six seconds. The time histories of rudder and aileron controls were studied as well. The analysis indicates that sharp change in crosswind affects the pilot control. As a result, the airplane ran out of the runway after its landing but was able to taxi back. The derivation of a proposed crosswind hazard index called “Redundancy” based on rudder and sideslip angles was developed and tested.