The LIDAR Windshear Alerting System (LIWAS) developed by the Hong Kong Observatory (HKO) has been put into operation at the Hong Kong International Airport (HKIA) to provide windshear alerts to the arriving aircraft since December 2005. This paper gives an update of the latest developments of LIWAS, covering the following areas: (a) Establishment of the accuracy of LIDAR-determined headwind profile in comparison to flight data from commercial aircraft; (b) Windshear alerting using the “runway dedicated LIDAR” concept; (c) Extending the windshear alerting algorithm to the departure corridors; and (d) Relationship between windshear ramp length and effect of windshear on the aircraft as revealed in pilot reports, flight data and LIDAR measurements.