Pitot Heat / Anti-Ice

[Nick Cserny]

Yes Tim, I agree with you there. I did get caught once with that in the RAAF. After that I
did learn and always did wet my fingers before touching to make sure, if I had doubts about being switched off without getting in the cockpit.

[Eagle737]

G'day Chris,

We are barking up the wrong tree.....what we were talking about is pitot heat and not de-icing of leading edges. Pitot heat is a 28VDC system and has nothing to do with bleed air. The reason they are turned on right before take off is, moisture within the head itself that can be from rain or condensation from the outside. Since temperature drops 2 degrees C per 1000 feet of altitude, it would not take much for the moisture to freeze after take off.
In response to someone's comment that the head would melt if overheated, it is incorrect, as it is only a 28V system and the heating element would burn out or the circuit breaker would "pop" well before the pitot head would reach the temperature of melting.
Blue skies....
Nick C

Hey Nick,

No he actually was bringing up anti-icing in his statement... in the post I responded to (the last one), he was talking actually about the anti-icing of the aircraft through the pneumatic systems in addition to the discussion of sensor heating. That is why I responded to that subject to give some insight on anti-icing of airliners. You will also notice all my other posts in here were in regards to sensor heating. This is the part of his statement I was responding to:

So I'll leave my anti-ice, window, and pitot heat on nonstop

[Nick Cserny]

Sorry Chris....my apologies.

[DMM200]

It's in the checklist for wing anti-ice to be on after takeoff, but the engine anti-ice can be turned on on the ground in a 747. I forgot to mention that I usually use the 747-400, my bad.

[maverick10]

You also have to turn the anti-ice on when flying in a lava cloud. Very rare, but it is a procedure in the KLM checklist.

Greetings,

Maverick10

[caps1237]

Stefan, please take care to check when the last post was made in a thread before replying. This is not the first time you've replied to a very old topic unfortunately. Thanks.