Page 236 - PPL-engelsk 2025

Meteorology

The top of the

transition layer is FL35,

which is 3500 feet

above 1013 hPa.

When converted to
the altitude relative to

QNH 1023 hPa, it is

300 feet higher, i.e., 3800 feet.

The vertical extent of the transition layer is then 3800 ÷ 3000 = 800 feet.

In the transition layer, commercial flight is not permitted. You must fly at
specific levels above the transition altitude. These levels (flight levels) depend

on the flight direction. In the subject of Air Law, you can learn more about this.

3.3.6.3 QNH, QFF, QFE, QNE

When flying at flight levels (FL), the lowest usable level is calculated based on

the current QNH.

In some countries, QFE is used, which is the pressure at the airport where the

altimeter reads 0.

What is the difference between QNH, QNE, QFE, and QFF, and who needs

which?

QNH is the pressure at the airport's official level, reduced to MSL according to

the standard atmosphere. This is how it should be so that the aircraft's

altimeter shows the correct reading.

The pilot needs to be able to set the

altimeter in the aircraft so that it shows

the aircraft's altitude above MSL.

He is given the QNH.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 236