It says in the Flight OPS Manual to use Anti-Ice if the temp is below 6C or if the Ice Detected light goes on. If I am flying at FL40 and my OAT is -24C but the Ice detected light isn't on should I run the system, and do most real flights run anti-ice when they are CRZ from point a to point b. will running the system without the ice detected light hurt the plane or expend more fuel. I'm probably over thinking this!

I'm sure someone will go into more detail but the basics are you only need it if visible moisture is in the air and the temp is below 6c. In crz generally it's too cold for ice to form unless in clouds or near thunderstorms. You should also be looking at the TAT not OAT in crz.Anti ice does burn more fuel as the bleed air requires a higher N1/EPR on the ground and in descent. One more thing, nothing wrong with turning it on if you expect icing conditions, it's designed to prevent ice rather then de-ice.Regards

I'm sure someone will go into more detail but the basics are you only need it if visible moisture is in the air and the temp is below 6c. In crz generally it's too cold for ice to form unless in clouds or near thunderstorms. You should also be looking at the TAT not OAT in crz.Anti ice does burn more fuel as the bleed air requires a higher N1/EPR on the ground and in descent. One more thing, nothing wrong with turning it on if you expect icing conditions, it's designed to prevent ice rather then de-ice.Regards

Thanks for the Info that makes sense!