121 deicing policy

[Dep676]

What is the de-icing policy at the 121 level? I have seen those guys getting sprayed before takeoff with clear skies out. Then other times it seems like they should and don't. The other night in ORD we had to wait 20 minutes to sprayed. After being delayed 30 minutes waiting for A/C to arrive. I came in about an hour before that on my other flight and there wasn't a even a trace of ice.

Then when we finally did take off. The layer was less then 500 feet thick and no ice. So what gives to waste all this money and time to get sprayed?

 

[Ted Striker]

We have a clean aircraft concept. It is possible to get ice on the underside of the wings in some aircraft with fuel in the wings. I have also been deiced on a CAVU day, due to the ice formation on the underside of the wing. Basically, if there is any contaminant on the a/c, we're getting sprayed. How thick the overcast is has no bearing on the decision. Hope that helps.

 

[amaineiac]

I think it may also depend on the A/C type. I've been told that MD-80's have some special deal with their tails during icing conditions. I'm sure some MD-80 pilot will be able to provide more info.

If it's just blowing dry snow that isn't sticking, we usually go without getting sprayed. If it's sticking, or if it's going to be a long taxi and we think its going to stick before we're #1, we get sprayed.

As Ted said, if the plane is clean, we usually go, if it isn't, we get sprayed.

Hope this helps.

 

[AWACoff]

We need critical surfaces clean only.

 

[Mickey]

Sometimes we don't need to be deiced but we do anyway because the weather is threatening to turn on us and we don't want to taxi to the runway only to have to taxi back to deice.

 

[Sphincter Boy]

On the E-145XR we have clear-ice detectors. Its possible to pick up a layer of ice when on the ground in humid air after flying at extremely cold altitudes foran extended period of time.

 

[typhoonpilot]

The deal with the MD-80s involves the formation of clear ice on the upper surface of the wing at temperatures as high as 15 Celcius. It will usually only occur with when the fuel in the main tanks is still fairly full and the fuel has been cold soaked from a flight at high altitude. The danger is that on a takeoff with that ice on the wing it will break off when the wing flexes right at liftoff and go straight back into the engine inlets, causing engine failure or serious damge in some instances. SAS had one plow into a field right after takeoff as a result of this happening. Fortunatley all on board survived.

Haven't heard of spraying for the underside as long as it is confined to the area of the fuel tanks only. My present company allows 3 mm thickness on the underside with no action necessary.

To further clarify some of the questions. Sometimes it is better not to spray, especially with the temp well below zero and just a light snow that doesn't adhere to the surface.

Typhoonpilot

 

[CFI'er]

Some day all critical surface areas will be sprayed with "Teflon"