A Study of Aircraft Wake Vortices at Hong Kong International Airport Using Short-Range LIDAR

The wake vortex of an aircraft can be hazardous to aviation operations. Therefore, the International Civil Aviation Organization has established requirements regarding the separation of aircraft. In light of the current implementation of regulations, this systematic study was the first of its kind investigating wake vortices of aircraft at the new north runway of Hong Kong International Airport (HKIA). A short-range light detection and ranging (SR-LIDAR) system, previously installed by the Hong Kong Observatory at HKIA, performed range–height indicator scans at the recently commissioned north runway end to capture wake vortices of arriving aircraft. The lifetimes of the wake vortices were calculated, and the exit times of the vortices away from the runway were determined. Based on an analysis of data from a period of approximately eight weeks—mostly during summer with its prevailing southwestern monsoon—it was found that, as in a previous study, the displacement of vortices increased with the radial background velocity. Moreover, approximately 0.6% of aircraft may be susceptible to encountering the vortex left behind by the preceding aircraft. Analysis of data from a second period of approximately four weeks revealed that vortex lifetimes were negatively correlated with the magnitude of the turbulence intensity expressed in terms of the eddy dissipation rate. Correlations with various other meteorological and non-meteorological factors were not apparent. The results of the present study supplement previous work in Hong Kong with a site-specific dataset for the new commissioned north runway, provide validation of established principles with an initial assessment of operational risk of turbulence encounter, and pave the way for longer-term statistical analysis of the behaviour of aircraft wake vortices in the climate of Hong Kong.