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Meteorology

3.3.6.5 Air density and flight performance

Aircraft perform best at MSL in dense air (cold air and high pressure).

At 5000 feet, the engine only performs at half capacity, and in order to achieve
the same IAS before takeoff, we need to go faster and farther on the runway,

and the climb angle will be less steep.

3.3.6.6 Venturi effect

Here you can see what happens

to the pressure when strong

winds blow over hills or

mountains.

Strong winds in mountainous

areas cause a drop in pressure
(Venturi effect).

The Venturi effect means that

you will be lower than the altimeter shows!

You can think of it as what happens when air rushes over the top of a wing. The

dynamic pressure of the air increases, but the static pressure drops.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 245