May I ask the question that has been bugging me for years. It relates to this discussion.
Fair enough that you must turn the Engine Anti-ice ON when the TAT drops below +10C. But why is it
so important that it be turned OFF when the temperature is +11C ?
This drives me nuts sometimes when the temperature is fluctuating around those figures!!
Also I can think of many situations where you know that you will be needing Anti-ice shortly as you are either climbing in cloud or you're clear of cloud but approaching some. You check the TAT and it's +13C. Then something distracts you or whatever. Next time you look it's +6C. AAAARGH!!
Why can't there be some overlap? For example, sure make it a requirement to have engine anti-ice on at +10C or below but
allow the engine anti-ice to be on up to +15C. That way in the situation above where it's +13C and expected to decrease, you can turn it on in anticipation and then turn your attention to something else.
Can someone with engineering knowledge tell us why this couldn't be done??
Thankyou.