Anti-ice operation

[nuNce 2]

Hello,I'm reading trough the FCOM Vol.1 and I've came across anti-ice operations. As far as I can see, the general suggestion is to use Engine AI and Wing AI anytime temperature is below 10°C (OAT or TAT if in flight) and icing conditions are present. As far as the EAI goes, if I understand correctly, it should be on anytime those conditions are present. But the manual states that it should be NOT be on "during climb and cruise when the temperature is below -40°C SAT". Can someone explain that to me? I'd expect it to be on when temperatures get below a certain point, not when they are above, but surely I am missing some important part. :)Regarding the WAI the FCOM got me confused with this statement "the wing anti-ice system may be used as a de-icer or anti-icer in flight only. So, can it be used on the ground or not? I understand that there is a risk of the melting ice on the leading edge of the wing freezing again on the surface, has it something to do with that?Another question: is the need to set engine start switches to continuous linked to the possible ingestion of ice trough the engine fan?Thank you.P.S.: I know that icing is not properly simulated in FSX, still want to get things right.

[Guest dlrk]

The engine anti-ice is turned off when the SAT is below -40 because any water in the air will already be frozen and unable to adhere to the aircraft. If they had to be on at all low temperatures, you'd spend every cruise with the anti-ice on.The WAI can be used on the ground, I believe it's only necessary with precipitation or standing or weather. It will automatically trip off when takeoff power is applied. In-flight it's only used when actual icing is suspected.Engine start switches are set to continuous to minimize the risk of flameout during critical phases of flight, by providing constant ignition from the active ignition system.

[Andrea1 6]

Hi,the only problem is that, if you're using Active Sky and flying into clouds and temp (rat) is below 6 C you have to insert wing antiice otherwise your speed indication will drop to "0" due to pitot tube frozen..the problem is that active sky doesn't recognize pitot heat "on" command just wing anti ice...(not very realistic)CiaoAndrea Buono

[Guest dlrk]

^Not true.

[Boeing or not going 578]

Hi,the only problem is that, if you're using Active Sky and flying into clouds and temp (rat) is below 6 C you have to insert wing antiice otherwise your speed indication will drop to "0" due to pitot tube frozen..the problem is that active sky doesn't recognize pitot heat "on" command just wing anti ice...(not very realistic)CiaoAndrea Buono

No that's wrong. It has nothing to do with Active Sky, it's how basic ice is modeled. Sometimes it's "Extreme" ice that overloads the systems, if you use FSUIPC you can change this, although I have never seen it with the latest versions of Active Sky.

[Andrea1 6]

Hi,I got an unregistered version of FSUIPC and the last version of Active Sky (Active sky 2012) but still have this problem. I've reduced the ice setting in active sky at 5% but nothing changedCiaoAndrea Buono

[japascoe 98]

Regarding the WAI the FCOM got me confused with this statement "the wing anti-ice system may be used as a de-icer or anti-icer in flight only. So, can it be used on the ground or not? I understand that there is a risk of the melting ice on the leading edge of the wing freezing again on the surface, has it something to do with that?Another question: is the need to set engine start switches to continuous linked to the possible ingestion of ice trough the engine fan?

You can use WAI on the ground, but not to remove ice that has formed on your plane while it was standing at the gate. In other words, what Boeing is trying to say is: using the WAI is not a replacement for having the guys in the de-icing trucks come over and hose down your plane.Start switches to continuous is linked to the possible ingestion of anything that could douse your engine flames, ice is one, but percipitation or even bird strike could also cause problems. Setting the ignition to continous ensures you won't lose engine power if the iginition is momentarily interupted.

[nuNce 2]

Just to clear things out a bit more, should be EAI turned on during takeoff, climb and cruise, given -40<SAT<10 and icing conditions are present?

[Guest dlrk]

Yes

[3-2-1-Now 126]

WAI is inhibited on the ground I think you'll find. You can switch it on but it won't do anything until the aircraft is airborne.

 

Best regards,

Robin.

[Guest dlrk]

It's not inhibited on the ground, and in fact if you set it on the ground, it will trip off when takeoff power is applied.

[pfpeter 3]

At witch altitude will you disable the EAI and WAI? Let us for the example say that the weather data are: Ground=+2, 3K=-1, 6K=-7.4, 9K=-10.9, 12K=16.6, 18K=-29.6, 24K=-40.4, 30K=-53.0

 

At what altitude will you turn off WAI and when to turn off EAI?

[Jack_C 1]

Well if you arent in icing conditions it would never be turned on! Dont over complicate things guys. This is pretty simple. Dont have the TAI on above 10. Heck the CDU will notify you if you do. Other than that, always have the TAI on until -40. Then its off. One exception though is on the descent.........always turn the TAI on.

JackColwill

[Guest dlrk]

Can you provide a source for always turning the TAI on during descent?

[WebMaximus 372]

Since WAI will automatically trip OFF during T/O when would you normally switch it back ON considered you're flying in icing conditions...right after T/O or wait until the a/c is clean?