De-ice-when to use it?

[beefhole]

Was wondering when use of de-ice was acceptable.  For example, the OAT is -3 degrees C.  At what points when on the ground is it acceptable to fire up the de-ice and pitot heat?  I know de-ice affects engine performance (albeit very, very little-unlike props) so i was thinking it may not be used on t/os or landings but for taxi.  Any insight?

[Eskimo]

De-ice is never used on the groud as the pitot head could overheat.  Only use it in the air.

In fact the conditions most likely to cause icing are temps over  20C and a relative humidity of over 50%.

[Rocket_Bird]

Ya, don't anti-ice on the ground, especially your pitot tube, or you might have to get one replaced .  It can depend on your aircraft though.  I would  say though, that most electrical types of anti-ice/de-ice systems should probably be kept off on the ground (due to inadequet cooling) unless just breaking off some chunks of ice that built up over night (in a real life situation, you can do it for kicks in flight sim ).  Pneumatic de-ice systems aernt that big of an issue, such as your deicer boots, they basically just inflate, break the chunks off, and deflate.

De-ice can affect engine performance depending on the type.  If its electrical, it won't really.  Pneumatics, maybe.  Some jet aircraft utilize engine bleed air, which definately robs the efficiency!

[Nexus]

The thermal wing anti-ice usage is restricted to inflight only (usually when OAT <+10C)
High pressure bleed air is routed under the leading edge surfaces to prevent the formation of ice.
As mention before, they sap a good deal of engine power.
Another problem is that the bleed air is so hot that use on the ground could lead to deformation of aluminum leading edge components, man that would make you look like a jackass

[beaky]

Hmmm... haven't really done much with heavies in FS, BUT- most of you may recall the accident in Wash. DC a while back... I believe it was a DC10 with a crew used to southern (warmer) routes. They were departing on a cold, snowy day and failed to turn on the engine inlet probe de-ice. The result was that they were seeing false readings of air intake velocity as they started the takeoff roll, but attributed this to the colder, denser air (seemed higher than normal at such an early point in the takeoff roll). The probes were of course frozen, so when they thought they were at Vr (despite conflicting reading from airspeed indicator vs. engine inlet readings), they weren't even close, and the power setting was lower than they thought. They managed to rotate, but with the deck angle trimmed for climbout with sufficient airspeed and thrust, the airliner stalled, and although they dumped the nose to try to get some airspeed back, they didn't have enough alt. and the plane pancaked into the Potomac, skimming a bridge choked with rush-hour traffic (many casualties on the bridge as well as aboard the airplane). I would imagine the checklist for this bird includes inlet probe heat for certain temps, and that system would be designed so as not to overheat if outside temp is low enough. As far as carb. heat for pistons goes, I was taught: never on the ground unless you're warming up before taxi on a very cold day, ABSOLUTELY not during takeoff, because it robs the engine of power, and in flight- whenever temps are 70F or below and there is visible moisture (remember. the temp. at that Venturi inlet on the carb. will always be much lower than the ambient temp). Or more precisely, one should be on guard for carb. ice under those conditions... loss of power should cause you to automatically turn on the carb. heat.

[beefhole]

K thanks guys  :)

[Nexus]

Rottydaddy, you got it all correct, but it was an Air Florida 737-200, not a DC-10.
But still, it was a tragic accident  :(

[TacitBlue]

Ive done a lot of FS flying in Alaska and Russia, and I have never noticed any ice problems, even when the OAT was very low. Does ice even happen in FS?

[Rocket_Bird]

A while ago I wondered that one myself.  But I flew a cessna citation in a thick snow storm once and all my instruments messed up until I turned on the anti-ice/deice

[beefhole]

Yup, thrice in my memory my airpseed has dropped to zero-on APPROACH of all times, and it happened when I was less experienced so I didn't know to turn on the pitot de-ice.  Basically, pitot tube ice builds up, as for wing ice I don't think so.

[logjam]

De-icing is well different from the pitot heater. De-icing is used to break up the ice that has started to form on the wing leading edge surfaces. On most aircraft, you may have noticed a black strip on the leading edge. This is actually made of a material such as very hard but resilient rubber. It is hollow and expands when the de-icing system fills it with hot air. It's not much use switching it on as a permanent thing, as the idea is to break up the thin ice that has started to form. If it already hasexpanded, it can't do it's job. The trick is to use it at the right time, turn it on and then turn it off so you can use it again. It's like a balloon really. Imagine a balloon half inflated covered in a thin layer of sugar icing. When you blow it up some more, the icing will crack and fall off.

[beefhole]

I was refering to in fs, I don't think wing de-ice builds up