When to turn NAI and WAI off ?

[JSACKS]

If I take off in snow and cold temps with clouds around and have NAI and WAI set to ON, at what point during the climb should I ideally turn both off?Also, what point in the descent is the optimal time to turn them back on if landing in similar conditions?Thanks.Jonathan

[rgamurot]

I don't know exactly but you can shut them off as soon as you are out of the moisture (rain, fog, clouds, etc.). I would wait a short while after clearing before finally shutting of the anti-ice. As for decent, I would switch it on before you reach cloud level or fog. Just be sure to turn off the NAI before touchdown as it won't let you use reverse thrust.EDIT: Nevermind, I see you already know about the NAI bug.Ryan GamurotLucky to live Hawai'ihttp://www.virtualpilots.org/signatures/vpa296.png

[rsrandazzo]

Jonathan-I have some guidance for anti-ice in the manual (i think...it's been awhile since i read it closely...)To help you though:Any time you are in temperature 10C or lower while in visible moisture. (That can be rain, fog, mist, snow, sleet, ice, hail, etc...)Hope that helps!

[downscc]

Based on AOPA Pilot magazine articles and AIM, I use ice protection in the range 10C to -10C. Seems to work real world.

[JSACKS]

OK, thanks all ! Appreciated.Jonathan

[VHOJT]

I'm pretty sure on the 744 nacelle anti-ice necessary in any visible moisture below 10 degrees C right down to -40 or so. I haven't checked the manual for a while but I'm pretty sure this is correct.

[martinboehme]

10 degrees is the number I remember, too. Just to clarify, that's TAT, not SAT... because TAT is what determines the skin surface temperature. In contrast, the -40 degree number below which anti-ice is not required is SAT, IIRC...Cheers,Martin Boehme