Use of wing anti ice (Airbus)
 

Can someone post the definitive on the correct use of wing anti ice on airbus aircraft. Does it have to be on at all times in icing conditions? The use of same as a deicer or an anti icer? Everyday's a school day................

FCOM 3.4.30 P1 says it can be used either to prevent or to remove ice.

i had the same question
 

i was just gonna ask the same question;).
Thanks for the reference.
:ok:

Just because it says it CAN be used to do two things doesn't mean you necessarily have the choice though. What do the Limitations say? - that's where it would be mandated.

caveat - non AB. But on the type I'm familiar with, our AI systems can also be used either to remove or prevent (any pneumatically heated system will be capable of both, basically). But we have an absolutely crystal clear Limitation that says it MUST be on in icing conditions. In our case the "can be used for removal" statement is somewhat superfluous.

Again, not a bus driver, but Wing Anti-Ice is ill-named on my type since Boeing recommends not to use it continuously as anti-ice due to the extremely high bleed air demand but instead to use it in cycles to break off accumulated ice. I'd be interested to know about the airbus though.

From Airbus Flight Crew Training Manual

"Wing Anti-Ice should be turned on, if either severe ice accretion is expected, or if there is any indication of icing on the airframe"


Seems a pretty straighforward statement.

@Wizzaird.

Problem with that statement is there's no "must" in the sentence, and it's not in the Airplane Flight Manual but rather a "training" manual. So it reads as "advice" not "instruction" or "requirement". A true Limitation would be worded more strongly, I think. (Ours are)

True, but nevertheless the FCTM was written to help in the interpretation of the AFM (A320) which simply states:



Turn on engine anti-ice.
Set wing anti-ice as required.

FCOM 3
 

I always thought wing anti ice are used to remove not to prevent but Airbus fcom says otherwise. Fcom 3.4.30-
WING ANTI ICE may either be used to prevent ice formation, or to remove ice accumulation from the wing leading edges

Question: If ice accumulation noticed on visual ice indicator or wipers, how long do u keep the WING ANTI ICE on?:confused:

Neupielot: In my experience of the A320 series, if you watch the leading edge after having selected the wing antice on, you can see the ice being shed from the leading edge. Once the flaps are selected to F1 an air gap opens up therefore the wing antice hot air is lost and the system is not effective and may therefore be switched off.

Incidently, the A330 & A340 seem to be much less prone to the build up of ice on the leading edge.

(return to bunker ready to accept incoming ............... )

From where did you get this? Own experience only?
I disagree. Even with slats extended, WAI is still going to heat outboard slats, and that, in severe icing can save your day.

The wing Leading edges are De-iced if selected on regardless of slat position.

Why not start with reading manufacturer's FCOM 3 Supplementary Procedures Ice & Rain Protection? ... whenever airframe icing is observed by accumulation on the icing indicator, etc ... ?

Sincerely
FD (the un-real)

Shortfuel: Many contributors here have referred to FCOM 3.04.30 P1 Suppl. Procedures. Under the advice given, in bold outline, Airbus have always said to avoid
"extended flight in icing conditions with slats extended"
Why do you think that is?

Once the gap in the leading edge is created by slat deployment you are not going to get the same heat transfer to the leading edge hence much less protection than when the leading edge is `closed`. This is Airbus admitting to you (warning you perhaps) that you should be aware of the lesser protection. Which now applies to the whole leading edge and not just the non heated areas.

All the types that I have flown with slats had similar considerations.

Meikleour,

Your second last post has nothing to do with the last one.
The one I referred to contains two wrong statements:

No hot air is lost whatsoever, same amount of hot air goes through outboard slats, thermal exchange is altered at most because of an increased heat exchange surface ("the gap").

That is the shocking part. Since when do you switch off a system because it is less effective?
Believing that WAI is not effective at all with slats extended is incorrect. WAI has its limitation, that's it.


I can only agree with the first part of your last post (first 3 lines).

IMHO, it is an aerodynamic consideration here: when slats are extended, wing curvature/AoA are increased, ice accretion is made easier because it's function of the wing curvature. I think this is why we try to avoid such a situation.
Having said that, it is not because WAI has not been designed(/certified?) to cope with extended flight in icing conditions w/ slats out that I would switch it off as you kindly suggested!


Anyway, Wizzaird answered the OP.

Using it as anti ice should be done with caution, as you run the risk (in the right conditions) of making the situation a lot worse by collecting a load of runback ice.

HundredPercentPlease:

With wings that use bleed air or with boots or both?

The wings can't even be seen from the flight deck on some transport airplanes.

Well, it is extremely unwise to use boots as 'anti-ice'? I cannot imagine anyone doing that.

'Run-back' ice is an age-old caution on all types I have flown with bleed de-icing and is, in my opinion, valid.

Shortfuel: you posted some time back:~ 2007

............................................................ ............................................................

I can only imagine that your company decided to associate WAI deselection during final with L/G extension.

Airbus proc extract:
-FLAPS FULL SELECT
Select FLAPS FULL below VFE.

-CONFIRM/ANNOUNCE "FLAPS FULL"

Check deceleration towards VAPP.
-A/THR CHECK IN SPEED MODE OR OFF

-WING ANTI ICE OFF
Only switch the WING ANTI ICE to ON, in severe icing conditions.

For Airbus, it comes after Flaps extension.

I don't think that it's related to OEI condition as you quote FCOM 3.03.18, normal procedures.
............................................................ ..................................................

Please explain to me how the above relates to the WAI efficiency being maintained when the slats are extended. Surely if full protection was given then Airbus would recommend it`s use until after landing ( like with the Engine AI ) My contention has always been that the WAI efficiency is much less with slats extended. Your reference to greater wing camber with slats out leading to greater ice accretion would not matter if the slats continued to be totally protected.

BOAC:

Never heard of it with respect to "hot" wings. Certainly have, though, with boots. My impression was that "hot" wings converted the ice to water, which did not reform as ice further back on the wing.

My former employer spend a lot of ground school time explaining the policy and critical nature of engine anti-ice. They spent very little time, however, on wing heat other than when not to use it (and reference to the OEM's AFM statements on use of wing heat). Nothing was ever mentioned about run-back ice. I don't believe I've heard of run-back ice stated as an issue with "hot wing" aircraft before this thread.

Ground deicing was a different matter, of course.