A tail strike event of an aircraft due to terrain-induced wind shear at the Hong Kong International Airport

摘要

At about 0155 UTC, 22 February 2009, an aircraft departing from the south runway of the Hong Kong International Airport to the east experienced significant wind shear of headwind loss. This may contribute towards the tail strike of the aircraft. This paper documents the meteorological observations in this tail strike event. The case occurs in a background atmosphere with a stable boundary layer and fresh east to southeasterly winds near the surface. The surface anemometer readings do not indicate the occurrence of significant headwind drop over the south runway. The glide-path scan data of a Doppler Light Detection and Ranging (LIDAR) system over the runway corridor concerned also do not indicate significant changes of the headwind due to blind zone of the LIDAR and geometrical constraint. However, the wind data measured on board the aircraft show that the tail strike may be due to a wind change from headwind of 19 knots to a tailwind of 5 knots over the western and middle parts of the south runway when the aircraft was on rotation. The headwind drop appears to be due to a jet of more easterly component near the surface occurring over the western part of the south runway. This drop could be captured if the LIDAR's headwind profiles over different runway corridors could be combined, and the present case suggests that, for wind shear alerting purposes, it may be necessary to try out combinations of headwind profiles over different parts of the same runway. The possibility of forecasting the significant wind shear in this case is also studied using a numerical weather prediction (NWP) model. The model results show that it may not be possible to forecast the event by using the direct model output alone, but would need to consider both the simulated wind direction as well as the forecast gust near the surface. Here the gust is forecast based on a physical approach as applied to the NWP model output.