Peter wrote:

wrote:

Does anyone know of an airplane manufacturer that specifies engine or
wing anti ice systems need to be activated a set amount of time
(minutes) prior to entering icing conditions? The ones I've seen only
say "prior to entering...", but no requirement given to have it on for
a set time prior in order to heat up the surfaces.

Do far 25 rules testing provide any insights?


With GA TKS systems, there is a low setting and a max setting. The
advice is to use the low setting prior to entry into IMC, and use the
high setting if icing is encountered - IIRC.

I fly with a prop-only TKS systems and I always use the high setting
only; 1 minute or so prior to entering freezing IMC.

Airliners are different - they generally use hot bleed air and can run
it indefinitely, power requirements (e.g. takeoff power) aside.
Whereas TKS will run out.

x----------x
Wing heat is de-ice. Engine heat is anti-ice.

Most airliners cannot use wing de-ice until after takeoff and at not
less than 400 feet; sometimes higher. The bleed air required for wing
de-ice takes so much power that it invalidates the takeoff flight path
performance.