De-icing

[HLD8391404]

I was sitting over the wing of a BA A319 last night that had the wings de-iced (briefly). I could see patches of ice over the full length of the wing, but they only de-iced the sections closed to the plane (not the tips).

Which part of a plane are adversely affected by ice? On the wings, is it only the flaps?

[hotmetal]

No ice allowed on wing upper surface. Are you sure it was ice towards the tips and not damp/de-icing spray/normal wing texture under apron lights. Sometimes its difficult to tell from the cabin. Where was this anyway? What was the temparature and was it snowing/raining?

[Leezyjet]

Which part of a plane are adversely affected by ice? On the wings, is it only the flaps?

Depends on the conditions (temp/precipitaion etc) as to how much is de-iced.

Usually the upper surfaces are de iced to ensure that the airflow is undisturbed as it flows over the wing surface. It might not appear cold outside, or even be snowing, but if the a/c has just landed from another flight, the fuel in the tanks could still be very very cold and cause ice to form on the wing especially if there is alot of moisture in the air - even in the height of summer you often see ice on the bottom inboard surface of the wings, it's quite refreshing some days to stand under the cold dripping water !!.

If it is really cold or snowing, then the movable surfaces are also de-iced. On the wings this includes slats, flaps and also ailerons. The elevators and rudder are also done too. If snow is really bad, it can even be necessary to blast it off the fuselage too as it adds extra weight to the a/c as well as degrading performance.

Hope that helped.

:ok:

[mp413]

Who makes the decision to de-ice, the pilot? I am curious because I remember hearing about a crash over the Potomac in Washington DC resulting from no/insufficient de-icing. I have also read (probably on this forum) about a situation where pax noticed only one wing was de-iced prior to take-off and lucily crew took him/her seriously. Is it pretty obvious when to de-ice or is such a decision prone to error?

[FlightDetent]

Pilot decides. And unless there is formalized requirement, s/he will not check the outcome. De-icing crew is normally better trained and knowledgable than the pilot, who has only certain gudelines. So any inputs from ground are welcome and very valuable. I suppose the error management/risk assesment is less developed with ground crew, however the operation itself is very simple and so are the rules. No ice on wings, ever, at all.

FD (the un-real)

[Rainboe]

.....except sometimes! Some jets are increasingly accepting contaminants within certain rigidly defined boundaries on the wing as being acceptable now.

[Rainboe]

.......and on the topside as well. The rules have changed for the 737NG, I don't know about Airbus, but if not already, it won't be long.

[OFBSLF]

Who makes the decision to de-ice, the pilot? I am curious because I remember hearing about a crash over the Potomac in Washington DC resulting from no/insufficient de-icing.That was Air Florida Flight 90:

http://en.wikipedia.org/wiki/Air_Florida_Flight_90

[10secondsurvey]

Once flew alaska air, in snowy conditions, and wings were thoroughly de-iced. Shortly after, aircraft taxied to runway, but before take off, First officer came back to have a look again at wings, and they said it was standard take off procedure at Alaska Air in icing conditions, to re-check just immediately before take off. It certainly made me feel safer.

Just wondering, is that approach standard practice in other airlines, or are Alaska just particularly thorough?

[Rainboe]

Air Alaska operates in very snowy conditions! One can make assessments from the flight deck about amount of precipitation falling or being blown, and can decide whether to go back and eyeball the wing yourself. I have done it where needed. It only need be done very rarely.

[alfamatt]

I'm pretty sure that BA operates a "clear wing" policy. ie NO ice anywhere on the wing.
The captain will have the final say, but when c,crew have noticed possible ice on the wing (anywhere on the wing) & told the T.crew, it is normally acted upon.
I would think that just de-icing the control surfaces wouldn't be enough, as I guess it would be possible for a large chunk/sheet of ice to come off the wing surface & jam/limit the movement of flap/aileron mechanism. Not good.
Matt.

[Rainboe]

Look, without being at all rude, this is an inexperienced observer. You cannot tell the difference between 'ice' and 'fluid' on the wing. But an accusation was made that BA operated a flight without adequate de-icing. This is a serious accusation to make. I know all BA pilots, especially Airbus crews, are very well aware of icing requirements and practices, so I'm adfraid I have to say the contents of Post 1 are misleading and incorrect. I have tried to answer as well as I can. If that was indeed 'ice' then that flight would not go anywhere.

There are previous posts on Search available about Icing for private research where HLD can make himself an expert. On the B737NG, there are now black lines painted around the wing where upper surface contamination is permitted, as long as it remains in that area.