747 anti-ice

[VHOJT 177]

Hi there - just saw the other MD-11 anti-ice thread and reminded me of a question I have. I know with the 744 at least, nacelle A/I is used when there is visible moisture and temp below 10 degrees celsius down to about -40 or so.Do clouds count as visible moisture? I would imagine so.As in, if there were a few clouds ceiling 2,000ft, scattered ceiling 5,000ft, and the temp at sea level was 2 degrees celsius, would I use anti-ice during takeoff or climb through these clouds?I remember reading about a BA777 that had auto anti-ice that switched on during descent through clouds, so I suppose I should?I take it I am going by OAT rather than TAT?Thanks if anyone could shed any light on this :)Kind regards,Rudy

[xkoote 57]

When considering to use anti ice, always reference the RAT/TAT numbers. That's one thing, as far as when to tuen on etc. In my personal real life experience, it is more of an persistent moisture condition that (judging from experience) will ead to possible icing.Or in any case if ice is detected on the windshield wipers. Otherwise flying through one or two clouds with a RAT below 10