Page 317 - PPL-engelsk 2025

Meteorology

OBSC TS: Thunderstorm clouds hidden in haze, difficult to spot. An IFR flight

can suddenly encounter a CB unless the pilot has carefully studied the weather.

EMBD TS: Thunderstorm clouds "hidden" between other clouds and thus

difficult to avoid.

FRQ TS: Frequent thunderstorm clouds, often hard to avoid.

SQL TS: A strong squall line that can also be difficult to avoid.

HVYGR: Severe hail – it’s dangerous to be hit by hail the size of tennis balls.

SEV TURB: Severe turbulence so intense that passengers are thrown around in

the aircraft, and the plane may be uncontrollable at times – areas to avoid flying

through.

SEV ICE and FZRA: Areas where there’s a risk of ice accumulating on the aircraft,

which, if not managed, can cause the plane to fall out of the sky.

SEV MTW: Phenomena occurring when there are strong winds over

mountainous areas. The turbulence and risk of severe downdrafts make it

dangerous to get too close to such weather.

TC followed by a name: Warning of a tropical cyclone – stay grounded.

HVY DS, HVY SS, and VA: Dangerous phenomena that should also be avoided.

SIGMETs are issued in real-time and may be updated or changed as needed if

the weather changes rapidly. The validity of a SIGMET can be no longer than 4
hours.

We retrieve SIGMETs from www.NorthAvimet.com, where we can choose

either text:

or graphical representations (next page).

By clicking on a region, you get the same warning as the text above provides.

The graphical presentation clearly shows, via color coding, where in the world

there are significant weather phenomena.

Clicking on a region displays the associated warning.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 317