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6. Low-Level Mechanical Turbulence

a. Low-level mechanical turbulence is turbulence near the ground that is caused by
wind flowing over and around obstructions. The obstructions can be large or tall buildings
and other man-made structures, hills, trees, etc. The amount and location of the turbulence
is dependent on the wind speed and direction it is blowing from. The turbulence forms
downwind from the obstruction, i.e., a west wind produces turbulence east of the
obstruction.

b. It is important for pilots of light aircraft to consider the variability of the wind
near the ground, particularly when landing or departing an airport. The landing area may
be safely upwind from an obstruction when an east wind is blowing, and yet be a turbulent
area because it is downwind from the same obstruction when a west wind is blowing.