WTWS Products
The primary WTWS product suite includes detection of terrain-induced turbulence, terrain-induced windshear, convective microburst and windshear, gust fronts, precipitation intensity and storm motion. It also predicts terrain-induced turbulence and airport surface wind and guides mesoscale numerical weather prediction guidance. The graphical and text formats are easily interpreted by pilots, controllers, air traffic managers and aviation forecasters. The alerts use commonly accepted aeronautical navigation terminology.
The WTWS graphic display (above) delivers hazardous weather warning information and other meteorological products. It shows the horizontal profile of various hazardous weather areas, vertical wind profiles near the approach and departure corridors, and textual warning messages. The meteorological situation is displayed in several user-selectable ranges and levels of detail. Critical products and important situation changes are highlighted visually on the display and/or announced by audible signals.
User needs were established over a two-year period culminating in a prototype demonstration in October 1995. As a result of comments by users, the system was designed to provide high performance, distinguish between the phenomena of windshear and turbulence, use existing aeronautical terminology and provide spatial extent of the phenomena as well as 12-hour forecasts of windshear and turbulence at a 30-minute resolution.
Alerts had to be reserved for significant events and assigned a priority. They also had to be concise but informative and provided within three nautical miles of runways. Products had to support both tactical and strategic decision making and be updated fast enough to cover operations that occur every two minutes.
The alphanumeric alarm display (above) is designed to alert controllers to time-critical weather hazards and to provide textual warnings for communication to pilots. Alerts are given as microburst, windshear or turbulence, with associated intensity and location. For windshear and microburst alerts, intensity is given as headwind "loss" or "gain" in knots; for turbulence, intensity is specified as "moderate" or "severe". The intensity is the maximum expected along the alert corridor and the alert location is where the event is first expected to be encountered. Event locations for windshear alerts are given as one, two or three nautical miles on approach or departure - or on the runway. Event locations for turbulence alerts are identified as departure or approach.
An artist–s rendition of the proposed airport site (before the airport was built) on Chek Lap Kok. Courtesy of Hong Kong Airport Authority.