Lanyu airport is located on the seashore near the foot of the hill at southwest of the Lanyu island which is around 100 m to the hillside with the runway aligning southeast- northwest. Since the northeast wind prevails in winter and the airport located at the leeward side of the hill, the air flows uphill from the northeast corner of the island and runs off the hill to the airport and the seashore with part of the airflow goes from the northwest and southeast corner of the island to the southwest shore, the strong low level windshear and turbulence often occur around the airport.
(7) What is turbulence? What's the difference between turbulence and windshear? How could we get the turbulence information of the Taipei FIR?
(7) What is turbulence? What's the difference between turbulence and windshear? How could we get the turbulence information of the Taipei FIR?
1. Turbulence is the vortex motions of the air caused by different reasons. While the scale of the turbulence is close to the size of the aircrafts (15 to 150m), the aircrafts are influenced by the turbulence and would be trembling and bumping that makes the aircrafts hard to control.
2. Windshear is one of the factors that induce turbulence.
3. Employees in the aviation field could obtain the turbulence information of the Taipei FIR through the following ways:
(1) "Products" of the Aeronautical Meteorological Service Page:
a. SIGMET: the height, area and strength of the SIG weather (includes turbulence) which already exists or is about to happen.
b. AIREP: the turbulent weather reports of the latest 24 hours.
c. SIGWX charts: the graphical data of the SIGMET.
d. Turbulence forecasting: the 6 hours forecast data of the turbulent weather.
e. JMDS: the integrated graphical forecasting data of the SIG weather, AIREP, SIGWX charts and turbulence forecasting.
(2) While the air traffic controllers receive the turbulence air reports, they would transmit the information to other pilots to remind them about the turbulent weather.
(8) How do the LLWAS systems installed at Songshan and Taoyuan airports operate?
(8) How do the LLWAS systems installed at Songshan and Taoyuan airports operate?
The LLWAS system is composed by setting anemometers in an array extending from both ends of the runway for every 1 to 3 NM(12 wind sensors at Songshan airport and 15 at Taoyuan airport) In the corridor on both sides of the runway. The LLWAS system detects the existence of low level windshear and microburst with the wind speed and wind direction data of perimeter sensors by recursive computation to derive the divergence data and the fluctuation of wind speed of either three sensors within 3NM extending from both sides of the runway and issue warning messages accordingly.
