Wednesday, 25 January 2012
A Tail Strike Event Due to Terrain-Induced Windshear At the Hong Kong International Airport in 2009
The complex terrain near the Hong Kong International Airport (HKIA) could bring about significant windshear to the arriving/departing aircraft in certain weather conditions. An event of tail strike experienced by a departing aircraft due to terrain-induced windshear in February 2009 is documented in this paper. In this event, southeasterly winds prevailed over Hong Kong, and the aircraft departed from the south runway of HKIA to the east (i.e. 07RD runway corridor). From the flight data of the aircraft, the tail strike may be related to headwind drop of about 24 knots during rotation. Due to geometrical limitation, the Light Detection And Ranging (LIDAR) system near the south runway did not capture the headwind drop based on the scanning over the 07RD runway corridor. However, by combining with the headwind profile of the LIDAR when scanning to the west (i.e. 07RA), it is possible to see there could be significant decrease of headwind over the western part of the runway. The possible forecasting of the event is attempted with the use of Regional Atmospheric Modelling System (RAMS) for numerical simulation down to a resolution of 50 m. The direct model output of the wind itself does not capture the headwind drop. However, by considering the gust product from RAMS, it may be seen that significant wind speed drop could appear at the western part of the south runway, and thus provide an earlier alert to the aviation weather forecaster about the chance of significant windshear over 07RD runway corridor.