Airbus Engine Anti-ice on descent

[John Citizen]

From the FCOM :

Flight in icing conditions :
Engine anti-ice :

ENGINE ANTI ICE must be ON before and during a descent in icing conditions, even if the SAT is below - 40° C.

How do you the interpret the above ?

Situation :

You are approaching top of descent in (day) VMC (not in icing condions at the moment) and well above the cloud (10'000' or more) with an SAT below -40 (ie. -56) at the moment. You will eventually encounter icing conditions later on in the descent.

1 interpretation :

You must select engine anti ice on NOW before commencing descent even though not in icing conditions at the moment but you eventually will be.
This is because the quote says "before and during descent...."

other interpretation :

No need to select engine anti ice on at top off descent or during descent until just "before" entering icing conditons. Even though well established in the descent you were not actually in icing conditons up until now (later on during the descent).


Does the "before" in the quote from the FCOM above mean :
- before commencing descent during which you will encounter icing conditons (not at the moment now but perhaps later on)
or
- just before entering icing conditons during descent

Descent in icing conditions ?

Does that mean if you are in icing conditons now and will be in continuous icing conditons for the whole descent or if just any (very momentarily) icing conditions expected on descent ?

[SMOC]

I take it you're using Rollers as we have the same restriction on the 744 with Rollers but not using Pratts.

Basically 'before' entering visible moisture on descent put the NAI on.

Unless while cruising in visible moisture then it will have to go on straight away, watch out for step descents as NAI is often forgotten.

[westinghouse]

if you cruising at 40,000ft and your not in clouds you dont have to select the engine anit-ice.
how ever if you are in clouds and the SAT is below -40 deg you will have to select it prior to descent.
during the descent engine anti should be on as long as there is visual moisture and your TAT is below +10deg.
Above +10 deg eng anti ice will net be needed.

[Chrome]

John Citizen the 'other interpretation' is correct. I think you are refering to 3.04.30 p1.

Flight in icing conditions :
Engine anti-ice
ENGINE ANTI ICE must be ON before and during a descent in icing conditions, even if the SAT is below - 40° C.

'In icing conditions' means both temperature and visible moisture must be present.

[TheGorrilla]

would these be the marvelous FCOMs translated from french into english by a french person who really doesn't give a t*^&s???

[411A]

With the Rollers on the L1011, I just turn engine anti-icing on, and leave it on, when icing is expected later on, during descent.
Makes life much easier...

[SIDSTAR]

Has common sense gone out the window? You put in on when you're about to enter cloud in the descent when the temp is below +10C. Why would you put it on in clear air? Remember "visible moisture" ?

Same for every type I've flown regardless of engine type.

[outhouse]

Try a search in the Middle East Forum; events back in 2006 re Double and Single Engine Failures on the A330 during decent. The report on cause was interesting but can’t remember the reference. As I remember icing on the fan was an issue. I expect an expert will be able to clarify. No published repeats on PPRuNe so assume it was fixed.

Blue Skies and safe Landings.

outhouse

[Boroda]

If you had connected your statement with the first part of FCOM text you would have not have such a question:"EAI must be on .... when the SAT is below -40".

[Dan Winterland]

Engines ice quicker at idle rather than full thrust. Airbus consider to negate the risk, you put EAI on at the top of descent.

I don't have a problem with it, so I do it.