eng anti ice
Most manuals state that at temperatures below -40c ,there is no need to switch on the eng anti ice,while in cruise.Are there any exceptions,cause i have always felt uncomfortable keeping the anti ice off in visible moisture,at temperatures beloww -40,specially in the tropics where the tropopause is around 52 thousand feet and we encounter active cb cells at 39000 ft.Could someone just clear away this doubt.thanks