De-icing question

Captain · Post by **Captain** » 27 Dec 2005, 19:59

Merry xmas luchtzakters,

Well, I was at BRU this afternoon waiting for a BA flight to LHR. As it's cold all planes underwent de-icing before take-off including the A319 I flew with.

I unfortunately didn't have my camera, but I was near the wing and saw a guy on a small crane spray a green coloured liquid to de-ice the wings and flaps. What is this green liquid? Is it bad for the environment? When it was Etihad's turn the guy even sprayed de-icing on the A330's winglets.

What's the length of time a plane can stay at the airport before having to be de-iced?

Captain

744rules · Post by **744rules** » 27 Dec 2005, 20:59

The green liquid is glycol. It is green so the operator has a better view on the areas that have been sprayed. Depending on weather conditions the operator uses a different mixure water/deicing fluid (25/75-50/50-or pure glycol). The mixture is also heated (but I don't know the temp).

The time the mixture is valid (hold over period) depends on the weather conditions (temp, light rain, heavy rain, light snow, heavy snow ....) and can vary from 4hours(cold but clear and dry) to 15minutes (heavy snow). This is one of the reasons why at some airports remote deicing is used.

twinsen · Post by **twinsen** » 27 Dec 2005, 21:16

What is the main purpose to this de-icing process? It's never been fully clear to me..

bits44 · Post by **bits44** » 27 Dec 2005, 21:23

In Canada at major Airports that are affected by severe winter weather such as Toronto and Montreal, and the Maritimes as well, they have drive through de-icing stations, the pilot just steers the plane through on his way to the runway, at Toronto they can do 6-8 planes at the same time. There has been work on a Air Dryer system under development for some time that will eliminate the use of chemicals, and will actually heat the metal of the aircraft, and should last longer than the glycol spray. Time will tell on that one.

KT

What is the main purpose to this de-icing process? It's never been fully clear to me..

The quick answer to your question is! ice or snow forming on wings and control surfaces alters the shape, thereby reducing or eliminating lift, many instances of aircraft failing to attain climb have been caused by ice or snow accumulation. To some degree deicing equipment built into the aircraft and engines will help eliminate icing! BUT not always.

Atlantis · Post by **Atlantis** » 27 Dec 2005, 22:01

twinsen wrote:What is the main purpose to this de-icing process? It's never been fully clear to me..

I will never forget the words of a pilot: "an aircraft with snow and ice on it, is an aircraft who will crash". He said this words after a crash of an airplane at the USA who was not de-iced and crashed into the water.

Captain · Post by **Captain** » 27 Dec 2005, 22:36

Thanks for the interesting info guys.

I could see on the de-icing truck that they were using Type II.

twinsen · Post by **twinsen** » 28 Dec 2005, 17:08

Good info, good info.. 8)

Sebas · Post by **Sebas** » 29 Dec 2005, 03:19

I noticed that the guy and his crane are going to the stand of the aircraft to perform the deicing (it was a calm moment at the airport when I watched the process).

What's then the use of the de-icing station at taxiway W2 if they're going to the stand anyway?

Is the de-icing station not used anymore, or is it only used at busy moments, or something else

Thanks for a clarification

Regards,
Sebas

744rules · Post by **744rules** » 29 Dec 2005, 11:04

Note there are still 2 handlingagents, BGS and AVP. There have been numerous talks about joint operation (1 bgs truck and 1 avp truck) for remote deicing, but I think so far only last year they used it.

I can tell you that a deicing is quite spectacular, but in the end it is just big chaos and delays.

I'll have the summer whole year round.

Knight255 · Post by **Knight255** » 29 Dec 2005, 15:19

I'll have the summer whole year round.

And have crappy airplane performance????

744rules · Post by **744rules** » 29 Dec 2005, 15:29

Knight255 wrote:
I'll have the summer whole year round.
And have crappy airplane performance????

as long temp stays under 25° C, I don't think there are heavy performance restrictions (when the best rwy configuration is used)

waldova · Post by **waldova** » 29 Dec 2005, 15:38

Yesterday I took the Vueling flight from BRU to VLC. They didn´t receive de-icing. Only the plains who were stationed at the terminal for a long period received de-icing.

Knight255 · Post by **Knight255** » 29 Dec 2005, 16:57

as long temp stays under 25° C, I don't think there are heavy performance restrictions (when the best rwy configuration is used)

What!?!?!? A summer under 25 degrees C?? Where are you from again? And best runway configurations are rarely used at ORD and DFW (the two airports I fly out of most of the time) so there is a problem there too... Sorry for being

fftopic: but I am amused.

realplaneshaveprops · Post by **realplaneshaveprops** » 29 Dec 2005, 18:26

There are some disadvantages on de-ice fluids, specially on type IV.

Type IV is a mix of 3 components: water, glycol,and thickener. The problem is that the thickener will set on the aerodynamic quit zones (between stabilizer and elevator, wing and aileron, ...). This can be seen as a very light grey layer of dust on the surface, it's hard to see. The layer will absorb water (humidity, rain). This will cause the layer to become ticker (5 to 6 times). If the temperature drops below freezing point, it will freeze and cause frozen flightcontrols.

Koen

Post by **Kapitein** » 30 Dec 2005, 09:39

waldova wrote:Yesterday I took the Vueling flight from BRU to VLC. They didn´t receive de-icing. Only the plains who were stationed at the terminal for a long period received de-icing.

In almost all the cases, a airplane that allready has flown will never be de-iced.
Can someone tell me why?

744rules · Post by **744rules** » 30 Dec 2005, 09:55

Brubiac wrote:
waldova wrote:Yesterday I took the Vueling flight from BRU to VLC. They didn´t receive de-icing. Only the plains who were stationed at the terminal for a long period received de-icing.
In almost all the cases, a airplane that allready has flown will never be de-iced.
Can someone tell me why?

The humidity is very important. Blue sky = dry air = no icing
In some cases, the fuel temp is high enough to avoid ice on the wing

Post by **Kapitein** » 30 Dec 2005, 12:10

Thanks for the info