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Meteorology
3.9.5.4 Gust front
When air meets the Earth's surface, it bends in all directions and can form a
gust front or roll cloud, which can be extremely dangerous, especially for
aircraft during takeoff or landing.
LLWS (Low-Level Windshear) refers to wind changes that lead to turbulence
below 1600 feet. This is reported during takeoff and landing.
A WS WRNG (Wind Shear Warning) is issued.
3.9.5.5 Microburst
In rare situations, a "microburst" can form.
A microburst is often a result of thunderstorm weather. It is an intense,
localized wind gust that occurs when cold air from a thunderstorm rapidly
descends to the ground and then spreads out when it hits the surface.
This can create strong downward winds that are very dangerous for aircraft,
especially during takeoff and landing.
You can see the principle in
the diagram here.
The descent rate of the air
can be between 2000 and
7000 feet per minute, with
wind speeds up to 145 knots. Microbursts are typically very short-lived (less
than 10 minutes).
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Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 332
