Strong Surface winds blowing through these passes can cause serious localized wind shears during the approach. The real problem with such shear is that it is almost totally urrpredictable in terms of magnitude of severity. A pilot can expect such shears whenever strong surface winds are present. Wind Shear Wind shear can be divided into horizontal and vertical shears. Although both components can affect an aircraft simultaneously, it is easier to discuss each separately.
Horizontal shear occurs when the flight path of an airplane passes through a wind shift plane.
Figure 4 shows how such a penetration would appear as an aircraft crosses a cold front. The other type is the one most often associated with an approach. The vertical shear is normal near the ground and can have the most serious effect on an aircratt. Wind shear in its many forms can, in a matter of seconds, change a routine approach into an emergency recovery. This has been a brief look at the kinds of wind shear and their sources.