At low or ultra-low altitude, due to the influence of ground friction, the airflow is often changeable; When the airflow passes through obstacles such as mountains, it often produces eddies of different sizes, causing turbulence; Due to the relative movement of the upper, lower, left and right airflow layers, sometimes strong wind shear will be formed at the junction; Different surface properties will also cause uneven air distribution and form lift air flow. Therefore, low-altitude or ultra-low-altitude flight will bring many difficulties to flight control and navigation. Baidu data: Low-altitude wind shear is a great threat to low-altitude flight. Why is low-altitude wind shear so harmful? This is caused by the nature of wind shear. Take the most harmful micro-downward flow as an example, which is a comprehensive wind shear zone characterized by vertical wind shear. Because there is a great velocity gradient in the airflow moving vertically in the horizontal direction, that is to say, the wind speed moving vertically will suddenly increase, which will produce a particularly strong downward airflow, which is called micro-undershoot airflow. This strong downward airflow exists in a limited area, and after colliding with the ground, it turns parallel to the ground and becomes a horizontal wind. The wind direction diverges around the impact point, so horizontal wind shear is formed again in a larger area. If the plane enters this area during take-off and landing, it may cause a crash. For example, when the plane lands, the glide path just passes through the micro-downward flow, then the plane will suddenly descend abnormally and deviate from the original glide path, and if the height is too low, it may cause danger. When the plane flies out of the micro-downward flow, it enters the downwind airflow again, which suddenly reduces the relative speed between the plane and the airflow. Because the plane is constantly slowing down during landing, we know that the flight speed of the plane must be greater than the minimum speed in order not to stall. Sudden deceleration is likely to stall the plane and the flight attitude is uncontrollable. At such a low altitude and speed, it is impossible to leave space and time for pilots to regain control, thus causing flight accidents. Wind shear is very harmful to aviation flight. In the process of taking off and landing, due to the low flight speed, wind shear will have a great impact on the airspeed of the aircraft, leading to a sudden change in the attitude and altitude of the aircraft, which is sometimes disastrous at low altitude.