Wind Shear Effects on Flights
Although airplanes are the safest transportation vehicles in terms of the percentage, someone could think it is the most dangerous. They would be right because aircraft crashes are generally fatal accidents. Winds are one of the most effective nature reasons under accidents and incidents. Especially, wind shear is really uncomfortable events during flights. Let we zoom in on it.
What is it?
Generally, wind shear is defined as it is a sudden change of wind speed and direction. Winds move freely in 3-D atmosphere, so it has speed and direction. Thanks to being instability of the air, the severity of winds could be sense differently in various levels of the atmosphere. If this differentness is huge, there would be a threat for airplanes. There are two types of wind shear as vertical and horizontal. Vertical wind shear mostly seen is the vertical variation of the horizontal wind component impacting aircraft. Horizontal wind shear is the horizontal variation of the horizontal wind component resulting in aircraft ground speed.
Where does it occur?
Wind shear is generally seen in CB clouds, mountain slopes, jet streams, and microburst phenomenons. Additionally, places where wind shear occurs are separated to two groups as low level and high level. Mountain wave and jet streams belongs to high level wind shear, particularly microburst is in low level class. Especially, microbursts are able to be mostly seen during landing and take-off. A sample of high level wind shear is flying over Rocky mountains in U.S. and Taurus mountains in Turkey.
How to calculate in a flight plan?
For example, your flight plan is at FL370 over point A. Firstly, divergence between above and below optimum flight level is 10 kt. Secondly, height between FL360 and FL380 is 2000'. The wind difference is divided by the height. As a result the vertical wind shear component is shown in the flight plan as “5”. Wind shear actually has no unit but the unit of kt/1000 ft could be used to call to mind.
Conclusion
Normally, wind shear is not seen in meteorological charts or in airplane weather radars. In addition to this, to detect a wind shear is really difficult with current radar technologies. Even if it could be forecasted, forecasts would not be consistent. Because wind shear incidents have no sufficient water droplets that reflect incoming radar impulses. However, airlines take into account it in order to increase passenger comfort and flight safety during flight planning. Some avoidance methods of a wind shear are awareness, route or flight level changing, and communication between pilots and ATC.
