Wing and Anti Ice affect performance?

[Robini]

Hello flyers out there,
The winter is approaching us....So one question came alive....
If you have selected both Engine and Wing Anti Ice (wich is normal under 10C of temp?) to ON, are you going to get better performance then?
And i have been reading somewere that you are loosing some FLEX temps.
-5C FLEX on A320 if my mind keeps strong...

Thanks!

//Robini

[mini-jumbo]

If you have wing and engine anti-ice on, or even just engine anti-ice, your performance will be reduced, as some bleed air is being used for purposes other than producing thrust.

[SNS3Guppy]

With the use of bleed air for anti-ice, you're going to see a slight drop in engine performance; either a slight loss of thrust with an attendant increase in temperature, or if compensated by increasing power, an even greater increase in temperature and higher fuel flows.

Any time you're stealing air from the engine, you're robbing performance in one way or another. It may be seen as a thrust decrease/EPR decrease, always as a temperature increase, and depending on the compensation made, as a fuel increase as well. The same is true of opening a third pack vs. leaving it off.

[lomapaseo]

I always have problems with interpreting in a question what is meant by performance when discussing a safety related feature

In simple form if you use the engine to power/heat something other than for pure thrust than you will either decrease available thust or increase temp and fuel flow to maintain thrust constant.

In the case of bleeding the compressor, you do gain some stability margin increase (against an engine surge condition) if you thought that you needed it.

I presume that safety has to be met first so you can always work out the priorities for many trades